101 files changed, 3940 insertions, 2405 deletions

diff --git a/logic/BaseInstaller.cpp b/logic/BaseInstaller.cpp
index 669fd0ac..5660eb07 100644
--- a/logic/BaseInstaller.cpp
+++ b/logic/BaseInstaller.cpp
@@ -13,15 +13,10 @@
  * limitations under the License.
  */
 
-#include "BaseInstaller.h"
-
 #include <QFile>
 
-#include "VersionFinal.h"
-#include "OneSixLibrary.h"
-#include "OneSixInstance.h"
-
-#include "cmdutils.h"
+#include "logic/BaseInstaller.h"
+#include "logic/OneSixInstance.h"
 
 BaseInstaller::BaseInstaller()
 {
diff --git a/logic/BaseInstaller.h b/logic/BaseInstaller.h
index d59833cc..9531fbff 100644
--- a/logic/BaseInstaller.h
+++ b/logic/BaseInstaller.h
@@ -29,7 +29,7 @@ class BaseInstaller
 {
 public:
 	BaseInstaller();
-
+	virtual ~BaseInstaller(){};
 	bool isApplied(OneSixInstance *on);
 
 	virtual bool add(OneSixInstance *to);
diff --git a/logic/BaseInstance.cpp b/logic/BaseInstance.cpp
index 5fa62593..15bf5ab6 100644
--- a/logic/BaseInstance.cpp
+++ b/logic/BaseInstance.cpp
@@ -27,7 +27,7 @@
 
 #include "pathutils.h"
 #include <cmdutils.h>
-#include "lists/MinecraftVersionList.h"
+#include "logic/minecraft/MinecraftVersionList.h"
 #include "logic/icons/IconList.h"
 
 BaseInstance::BaseInstance(BaseInstancePrivate *d_in, const QString &rootDir,
@@ -58,6 +58,8 @@ BaseInstance::BaseInstance(BaseInstancePrivate *d_in, const QString &rootDir,
 
 	// Java Settings
 	settings().registerSetting("OverrideJava", false);
+	settings().registerSetting("OverrideJavaLocation", false);
+	settings().registerSetting("OverrideJavaArgs", false);
 	settings().registerOverride(globalSettings->getSetting("JavaPath"));
 	settings().registerOverride(globalSettings->getSetting("JvmArgs"));
 
@@ -104,6 +106,18 @@ QString BaseInstance::id() const
 	return QFileInfo(instanceRoot()).fileName();
 }
 
+bool BaseInstance::isRunning() const
+{
+	I_D(BaseInstance);
+	return d->m_isRunning;
+}
+
+void BaseInstance::setRunning(bool running) const
+{
+	I_D(BaseInstance);
+	d->m_isRunning = running;
+}
+
 QString BaseInstance::instanceType() const
 {
 	I_D(BaseInstance);
diff --git a/logic/BaseInstance.h b/logic/BaseInstance.h
index 16791592..5f5378e7 100644
--- a/logic/BaseInstance.h
+++ b/logic/BaseInstance.h
@@ -22,9 +22,10 @@
 #include <settingsobject.h>
 
 #include "inifile.h"
-#include "lists/BaseVersionList.h"
+#include "logic/BaseVersionList.h"
 #include "logic/auth/MojangAccount.h"
 
+class ModList;
 class QDialog;
 class QDir;
 class Task;
@@ -64,6 +65,9 @@ public:
 	/// be unique.
 	virtual QString id() const;
 
+	virtual void setRunning(bool running) const;
+	virtual bool isRunning() const;
+
 	/// get the type of this instance
 	QString instanceType() const;
 
@@ -89,7 +93,7 @@ public:
 	void setGroupInitial(QString val);
 	void setGroupPost(QString val);
 
-	QStringList extraArguments() const;
+	virtual QStringList extraArguments() const;
 
 	virtual QString intendedVersionId() const = 0;
 	virtual bool setIntendedVersionId(QString version) = 0;
@@ -110,6 +114,19 @@ public:
 	virtual bool shouldUpdate() const = 0;
 	virtual void setShouldUpdate(bool val) = 0;
 
+	//////  Mod Lists  //////
+	virtual std::shared_ptr<ModList> resourcePackList()
+	{
+		return nullptr;
+	}
+	virtual std::shared_ptr<ModList> texturePackList()
+	{
+		return nullptr;
+	}
+	
+	/// Traits. Normally inside the version, depends on instance implementation.
+	virtual QSet <QString> traits() = 0;
+
 	/// Get the curent base jar of this instance. By default, it's the
 	/// versions/$version/$version.jar
 	QString baseJar() const;
@@ -169,12 +186,6 @@ public:
 	/// 'prepareForLaunch'
 	virtual void cleanupAfterRun() = 0;
 
-	/// create a mod edit dialog for the instance
-	virtual QDialog *createModEditDialog(QWidget *parent) = 0;
-
-	/// is a particular action enabled with this instance selected?
-	virtual bool menuActionEnabled(QString action_name) const = 0;
-
 	virtual QString getStatusbarDescription() = 0;
 
 	/// FIXME: this really should be elsewhere...
diff --git a/logic/BaseInstance_p.h b/logic/BaseInstance_p.h
index 999ff545..6498454f 100644
--- a/logic/BaseInstance_p.h
+++ b/logic/BaseInstance_p.h
@@ -32,4 +32,5 @@ public:
 	QString m_group;
 	std::shared_ptr<SettingsObject> m_settings;
 	QSet<BaseInstance::InstanceFlag> m_flags;
+	bool m_isRunning = false;
 };
diff --git a/logic/BaseVersion.h b/logic/BaseVersion.h
index 43f5942a..ed63f551 100644
--- a/logic/BaseVersion.h
+++ b/logic/BaseVersion.h
@@ -16,6 +16,8 @@
 #pragma once
 
 #include <memory>
+#include <QString>
+#include <QMetaType>
 
 /*!
  * An abstract base class for versions.
@@ -52,4 +54,4 @@ struct BaseVersion
 
 typedef std::shared_ptr<BaseVersion> BaseVersionPtr;
 
-Q_DECLARE_METATYPE(BaseVersionPtr)
\ No newline at end of file
+Q_DECLARE_METATYPE(BaseVersionPtr)
diff --git a/logic/lists/BaseVersionList.cpp b/logic/BaseVersionList.cpp
index 6e2c5282..b34750b5 100644
--- a/logic/lists/BaseVersionList.cpp
+++ b/logic/BaseVersionList.cpp
@@ -13,7 +13,7 @@
  * limitations under the License.
  */
 
-#include "logic/lists/BaseVersionList.h"
+#include "logic/BaseVersionList.h"
 #include "logic/BaseVersion.h"
 
 BaseVersionList::BaseVersionList(QObject *parent) : QAbstractListModel(parent)
diff --git a/logic/lists/BaseVersionList.h b/logic/BaseVersionList.h
index 21b44e8d..21b44e8d 100644
--- a/logic/lists/BaseVersionList.h
+++ b/logic/BaseVersionList.h
diff --git a/logic/InstanceFactory.cpp b/logic/InstanceFactory.cpp
index 95fd855b..c0a392e0 100644
--- a/logic/InstanceFactory.cpp
+++ b/logic/InstanceFactory.cpp
@@ -13,28 +13,26 @@
  * limitations under the License.
  */
 
-#include "InstanceFactory.h"
-
 #include <QDir>
 #include <QFileInfo>
-
-#include "BaseInstance.h"
-#include "LegacyInstance.h"
-#include "LegacyFTBInstance.h"
-#include "OneSixInstance.h"
-#include "OneSixFTBInstance.h"
-#include "NostalgiaInstance.h"
-#include "OneSixInstance.h"
-#include "BaseVersion.h"
-#include "MinecraftVersion.h"
-
-#include "inifile.h"
+#include <inifile.h>
 #include <inisettingsobject.h>
 #include <setting.h>
 
-#include "pathutils.h"
+#include <pathutils.h>
 #include "logger/QsLog.h"
 
+#include "logic/InstanceFactory.h"
+
+#include "logic/BaseInstance.h"
+#include "logic/LegacyInstance.h"
+#include "logic/LegacyFTBInstance.h"
+#include "logic/OneSixInstance.h"
+#include "logic/OneSixFTBInstance.h"
+#include "logic/OneSixInstance.h"
+#include "logic/BaseVersion.h"
+#include "logic/minecraft/MinecraftVersion.h"
+
 InstanceFactory InstanceFactory::loader;
 
 InstanceFactory::InstanceFactory() : QObject(NULL)
@@ -51,7 +49,7 @@ InstanceFactory::InstLoadError InstanceFactory::loadInstance(InstancePtr &inst,
 	QString inst_type = m_settings->get("InstanceType").toString();
 
 	// FIXME: replace with a map lookup, where instance classes register their types
-	if (inst_type == "OneSix")
+	if (inst_type == "OneSix" || inst_type == "Nostalgia")
 	{
 		inst.reset(new OneSixInstance(instDir, m_settings, this));
 	}
@@ -59,10 +57,6 @@ InstanceFactory::InstLoadError InstanceFactory::loadInstance(InstancePtr &inst,
 	{
 		inst.reset(new LegacyInstance(instDir, m_settings, this));
 	}
-	else if (inst_type == "Nostalgia")
-	{
-		inst.reset(new NostalgiaInstance(instDir, m_settings, this));
-	}
 	else if (inst_type == "LegacyFTB")
 	{
 		inst.reset(new LegacyFTBInstance(instDir, m_settings, this));
@@ -98,55 +92,26 @@ InstanceFactory::InstCreateError InstanceFactory::createInstance(InstancePtr &in
 
 	if (type == NormalInst)
 	{
-		switch (mcVer->type)
-		{
-		case MinecraftVersion::Legacy:
-			// TODO new instance type
-			m_settings->set("InstanceType", "Legacy");
-			inst.reset(new LegacyInstance(instDir, m_settings, this));
-			inst->setIntendedVersionId(version->descriptor());
-			inst->setShouldUseCustomBaseJar(false);
-			break;
-		case MinecraftVersion::OneSix:
-			m_settings->set("InstanceType", "OneSix");
-			inst.reset(new OneSixInstance(instDir, m_settings, this));
-			inst->setIntendedVersionId(version->descriptor());
-			inst->setShouldUseCustomBaseJar(false);
-			break;
-		case MinecraftVersion::Nostalgia:
-			m_settings->set("InstanceType", "Nostalgia");
-			inst.reset(new NostalgiaInstance(instDir, m_settings, this));
-			inst->setIntendedVersionId(version->descriptor());
-			inst->setShouldUseCustomBaseJar(false);
-			break;
-		default:
-		{
-			delete m_settings;
-			return InstanceFactory::NoSuchVersion;
-		}
-		}
+		m_settings->set("InstanceType", "OneSix");
+		inst.reset(new OneSixInstance(instDir, m_settings, this));
+		inst->setIntendedVersionId(version->descriptor());
+		inst->setShouldUseCustomBaseJar(false);
 	}
 	else if (type == FTBInstance)
 	{
-		switch (mcVer->type)
+		if(mcVer->usesLegacyLauncher())
 		{
-		case MinecraftVersion::Legacy:
 			m_settings->set("InstanceType", "LegacyFTB");
 			inst.reset(new LegacyFTBInstance(instDir, m_settings, this));
 			inst->setIntendedVersionId(version->descriptor());
 			inst->setShouldUseCustomBaseJar(false);
-			break;
-		case MinecraftVersion::OneSix:
+		}
+		else
+		{
 			m_settings->set("InstanceType", "OneSixFTB");
 			inst.reset(new OneSixFTBInstance(instDir, m_settings, this));
 			inst->setIntendedVersionId(version->descriptor());
 			inst->setShouldUseCustomBaseJar(false);
-			break;
-		default:
-		{
-			delete m_settings;
-			return InstanceFactory::NoSuchVersion;
-		}
 		}
 	}
 	else
diff --git a/logic/InstanceLauncher.cpp b/logic/InstanceLauncher.cpp
index c0079d80..9170c87f 100644
--- a/logic/InstanceLauncher.cpp
+++ b/logic/InstanceLauncher.cpp
@@ -22,7 +22,7 @@
 #include "gui/dialogs/ProgressDialog.h"
 
 #include "logic/MinecraftProcess.h"
-#include "logic/lists/InstanceList.h"
+#include "logic/InstanceList.h"
 
 InstanceLauncher::InstanceLauncher(QString instId) : QObject(), instId(instId)
 {
diff --git a/logic/lists/InstanceList.cpp b/logic/InstanceList.cpp
index 1ff0d2ec..5a988fd3 100644
--- a/logic/lists/InstanceList.cpp
+++ b/logic/InstanceList.cpp
@@ -27,13 +27,13 @@
 #include <pathutils.h>
 
 #include "MultiMC.h"
-#include "logic/lists/InstanceList.h"
+#include "logic/InstanceList.h"
 #include "logic/icons/IconList.h"
-#include "logic/lists/MinecraftVersionList.h"
+#include "logic/minecraft/MinecraftVersionList.h"
 #include "logic/BaseInstance.h"
 #include "logic/InstanceFactory.h"
 #include "logger/QsLog.h"
-#include <gui/groupview/GroupView.h>
+#include "gui/groupview/GroupView.h"
 
 const static int GROUP_FILE_FORMAT_VERSION = 1;
 
@@ -46,16 +46,6 @@ InstanceList::InstanceList(const QString &instDir, QObject *parent)
 	{
 		QDir::current().mkpath(m_instDir);
 	}
-
-	/*
-	 * FIXME HACK: instances sometimes need to be created at launch. They need the versions for
-	 * that.
-	 *
-	 * Remove this. it has no business of reloading the whole list. The instances which
-	 * need it should track such events themselves and CHANGE THEIR DATA ONLY!
-	 */
-	connect(MMC->minecraftlist().get(), &MinecraftVersionList::modelReset, this,
-			&InstanceList::loadList);
 }
 
 InstanceList::~InstanceList()
@@ -296,17 +286,16 @@ void InstanceList::loadGroupList(QMap<QString, QString> &groupMap)
 QList<FTBRecord> InstanceList::discoverFTBInstances()
 {
 	QList<FTBRecord> records;
-	QDir dir = QDir(MMC->settings()->get("FTBLauncherRoot").toString());
+	QDir dir = QDir(MMC->settings()->get("FTBLauncherDataRoot").toString());
 	QDir dataDir = QDir(MMC->settings()->get("FTBRoot").toString());
-	if (!dir.exists())
+	if (!dataDir.exists())
 	{
-		QLOG_INFO() << "The FTB launcher directory specified does not exist. Please check your "
-					   "settings.";
+		QLOG_INFO() << "The FTB directory specified does not exist. Please check your settings";
 		return records;
 	}
-	else if (!dataDir.exists())
+	else if (!dir.exists())
 	{
-		QLOG_INFO() << "The FTB directory specified does not exist. Please check your settings";
+		QLOG_INFO() << "The FTB launcher data directory specified does not exist. Please check your settings";
 		return records;
 	}
 	dir.cd("ModPacks");
@@ -337,6 +326,7 @@ QList<FTBRecord> InstanceList::discoverFTBInstances()
 					record.instanceDir = dataDir.absoluteFilePath(record.dirName);
 					record.templateDir = dir.absoluteFilePath(record.dirName);
 					QDir test(record.instanceDir);
+					QLOG_DEBUG() << dataDir.absolutePath() << record.instanceDir << record.dirName;
 					if (!test.exists())
 						continue;
 					record.name = attrs.value("name").toString();
diff --git a/logic/lists/InstanceList.h b/logic/InstanceList.h
index f0bbb7ec..f0bbb7ec 100644
--- a/logic/lists/InstanceList.h
+++ b/logic/InstanceList.h
diff --git a/logic/LegacyFTBInstance.cpp b/logic/LegacyFTBInstance.cpp
index 3c3356c9..73a1f73d 100644
--- a/logic/LegacyFTBInstance.cpp
+++ b/logic/LegacyFTBInstance.cpp
@@ -14,11 +14,6 @@ QString LegacyFTBInstance::getStatusbarDescription()
 	return "Legacy FTB: " + intendedVersionId();
 }
 
-bool LegacyFTBInstance::menuActionEnabled(QString action_name) const
-{
-	return false;
-}
-
 QString LegacyFTBInstance::id() const
 {
 	return "FTB/" + BaseInstance::id();
diff --git a/logic/LegacyFTBInstance.h b/logic/LegacyFTBInstance.h
index 70f60535..a2fe1ead 100644
--- a/logic/LegacyFTBInstance.h
+++ b/logic/LegacyFTBInstance.h
@@ -9,6 +9,5 @@ public:
 	explicit LegacyFTBInstance(const QString &rootDir, SettingsObject *settings,
 							   QObject *parent = 0);
 	virtual QString getStatusbarDescription();
-	virtual bool menuActionEnabled(QString action_name) const;
 	virtual QString id() const;
 };
diff --git a/logic/LegacyInstance.cpp b/logic/LegacyInstance.cpp
index 6648e059..5c15616a 100644
--- a/logic/LegacyInstance.cpp
+++ b/logic/LegacyInstance.cpp
@@ -28,8 +28,13 @@
 #include "logic/MinecraftProcess.h"
 #include "logic/LegacyUpdate.h"
 #include "logic/icons/IconList.h"
-
-#include "gui/dialogs/LegacyModEditDialog.h"
+#include "gui/pages/LegacyUpgradePage.h"
+#include "gui/pages/ModFolderPage.h"
+#include "gui/pages/LegacyJarModPage.h"
+#include <gui/pages/TexturePackPage.h>
+#include <gui/pages/InstanceSettingsPage.h>
+#include <gui/pages/NotesPage.h>
+#include <gui/pages/ScreenshotsPage.h>
 
 LegacyInstance::LegacyInstance(const QString &rootDir, SettingsObject *settings,
 							   QObject *parent)
@@ -42,6 +47,27 @@ LegacyInstance::LegacyInstance(const QString &rootDir, SettingsObject *settings,
 	settings->registerSetting("IntendedJarVersion", "");
 }
 
+QList<BasePage *> LegacyInstance::getPages()
+{
+	QList<BasePage *> values;
+	values.append(new LegacyUpgradePage(this));
+	values.append(new LegacyJarModPage(this));
+	values.append(new ModFolderPage(this, loaderModList(), "mods", "plugin-blue", tr("Loader mods"),
+									"Loader-mods"));
+	values.append(new ModFolderPage(this, coreModList(), "coremods", "plugin-green", tr("Core mods"),
+									"Core-mods"));
+	values.append(new TexturePackPage(this));
+	values.append(new NotesPage(this));
+	values.append(new ScreenshotsPage(this));
+	values.append(new InstanceSettingsPage(this));
+	return values;
+}
+
+QString LegacyInstance::dialogTitle()
+{
+	return tr("Edit Instance (%1)").arg(name());
+}
+
 std::shared_ptr<Task> LegacyInstance::doUpdate()
 {
 	// make sure the jar mods list is initialized by asking for it.
@@ -50,7 +76,7 @@ std::shared_ptr<Task> LegacyInstance::doUpdate()
 	return std::shared_ptr<Task>(new LegacyUpdate(this, this));
 }
 
-bool LegacyInstance::prepareForLaunch(AuthSessionPtr account, QString & launchScript)
+bool LegacyInstance::prepareForLaunch(AuthSessionPtr account, QString &launchScript)
 {
 	QIcon icon = MMC->icons()->getIcon(iconKey());
 	auto pixmap = icon.pixmap(128, 128);
@@ -136,11 +162,6 @@ std::shared_ptr<ModList> LegacyInstance::texturePackList()
 	return d->texture_pack_list;
 }
 
-QDialog *LegacyInstance::createModEditDialog(QWidget *parent)
-{
-	return new LegacyModEditDialog(this, parent);
-}
-
 QString LegacyInstance::jarModsDir() const
 {
 	return PathCombine(instanceRoot(), "instMods");
@@ -263,27 +284,11 @@ QString LegacyInstance::defaultCustomBaseJar() const
 	return PathCombine(binDir(), "mcbackup.jar");
 }
 
-bool LegacyInstance::menuActionEnabled(QString action_name) const
-{
-	if (flags().contains(VersionBrokenFlag))
-	{
-		return false;
-	}
-	if (action_name == "actionChangeInstMCVersion")
-	{
-		return false;
-	}
-	return true;
-}
-
 QString LegacyInstance::getStatusbarDescription()
 {
 	if (flags().contains(VersionBrokenFlag))
 	{
-		return "Legacy : " + intendedVersionId() + " (broken)";
+		return tr("Legacy : %1 (broken)").arg(intendedVersionId());
 	}
-	if (shouldUpdate())
-		return "Legacy : " + currentVersionId() + " -> " + intendedVersionId();
-	else
-		return "Legacy : " + currentVersionId();
+	return tr("Legacy : %1").arg(intendedVersionId());
 }
diff --git a/logic/LegacyInstance.h b/logic/LegacyInstance.h
index aa80968e..76a8c24d 100644
--- a/logic/LegacyInstance.h
+++ b/logic/LegacyInstance.h
@@ -16,11 +16,12 @@
 #pragma once
 
 #include "BaseInstance.h"
+#include "gui/pages/BasePageProvider.h"
 
 class ModList;
 class Task;
 
-class LegacyInstance : public BaseInstance
+class LegacyInstance : public BaseInstance, public BasePageProvider
 {
 	Q_OBJECT
 public:
@@ -34,6 +35,10 @@ public:
 	//! Path to the instance's modlist file.
 	QString modListFile() const;
 
+	////// Edit Instance Dialog stuff //////
+	virtual QList<BasePage *> getPages();
+	virtual QString dialogTitle();
+
 	//////  Mod Lists  //////
 	std::shared_ptr<ModList> jarModList();
 	std::shared_ptr<ModList> coreModList();
@@ -75,18 +80,21 @@ public:
 		return false;
 	}
 
+	virtual QSet<QString> traits()
+	{
+		return {"legacy-instance", "texturepacks"};
+	};
+
 	virtual bool shouldUpdate() const override;
 	virtual void setShouldUpdate(bool val) override;
 	virtual std::shared_ptr<Task> doUpdate() override;
 
 	virtual bool prepareForLaunch(AuthSessionPtr account, QString & launchScript) override;
 	virtual void cleanupAfterRun() override;
-	virtual QDialog *createModEditDialog(QWidget *parent) override;
 
 	virtual QString defaultBaseJar() const override;
 	virtual QString defaultCustomBaseJar() const override;
 
-	bool menuActionEnabled(QString action_name) const;
 	virtual QString getStatusbarDescription() override;
 
 protected
diff --git a/logic/LegacyUpdate.cpp b/logic/LegacyUpdate.cpp
index 15c99234..00ee795d 100644
--- a/logic/LegacyUpdate.cpp
+++ b/logic/LegacyUpdate.cpp
@@ -13,69 +13,27 @@
  * limitations under the License.
  */
 
-#include "LegacyUpdate.h"
-#include "lists/LwjglVersionList.h"
-#include "lists/MinecraftVersionList.h"
-#include "BaseInstance.h"
-#include "LegacyInstance.h"
-#include "MultiMC.h"
-#include "ModList.h"
+#include <QStringList>
+
 #include <pathutils.h>
 #include <quazip.h>
 #include <quazipfile.h>
 #include <JlCompress.h>
+
+#include "logic/LegacyUpdate.h"
+#include "logic/LwjglVersionList.h"
+#include "logic/minecraft/MinecraftVersionList.h"
+#include "logic/BaseInstance.h"
+#include "logic/LegacyInstance.h"
+#include "MultiMC.h"
+#include "logic/ModList.h"
+
 #include "logger/QsLog.h"
 #include "logic/net/URLConstants.h"
-#include <QStringList>
+
 
 LegacyUpdate::LegacyUpdate(BaseInstance *inst, QObject *parent) : Task(parent), m_inst(inst)
 {
-	// 1.3 - 1.3.2
-	auto libs13 = QList<FMLlib>{
-		{"argo-2.25.jar", "bb672829fde76cb163004752b86b0484bd0a7f4b", false},
-		{"guava-12.0.1.jar", "b8e78b9af7bf45900e14c6f958486b6ca682195f", false},
-		{"asm-all-4.0.jar", "98308890597acb64047f7e896638e0d98753ae82", false}};
-
-	fmlLibsMapping["1.3.2"] = libs13;
-
-	auto libs14 = QList<FMLlib>{
-		{"argo-2.25.jar", "bb672829fde76cb163004752b86b0484bd0a7f4b", false},
-		{"guava-12.0.1.jar", "b8e78b9af7bf45900e14c6f958486b6ca682195f", false},
-		{"asm-all-4.0.jar", "98308890597acb64047f7e896638e0d98753ae82", false},
-		{"bcprov-jdk15on-147.jar", "b6f5d9926b0afbde9f4dbe3db88c5247be7794bb", false}};
-
-	fmlLibsMapping["1.4"] = libs14;
-	fmlLibsMapping["1.4.1"] = libs14;
-	fmlLibsMapping["1.4.2"] = libs14;
-	fmlLibsMapping["1.4.3"] = libs14;
-	fmlLibsMapping["1.4.4"] = libs14;
-	fmlLibsMapping["1.4.5"] = libs14;
-	fmlLibsMapping["1.4.6"] = libs14;
-	fmlLibsMapping["1.4.7"] = libs14;
-
-	fmlLibsMapping["1.5"] = QList<FMLlib>{
-		{"argo-small-3.2.jar", "58912ea2858d168c50781f956fa5b59f0f7c6b51", false},
-		{"guava-14.0-rc3.jar", "931ae21fa8014c3ce686aaa621eae565fefb1a6a", false},
-		{"asm-all-4.1.jar", "054986e962b88d8660ae4566475658469595ef58", false},
-		{"bcprov-jdk15on-148.jar", "960dea7c9181ba0b17e8bab0c06a43f0a5f04e65", true},
-		{"deobfuscation_data_1.5.zip", "5f7c142d53776f16304c0bbe10542014abad6af8", false},
-		{"scala-library.jar", "458d046151ad179c85429ed7420ffb1eaf6ddf85", true}};
-
-	fmlLibsMapping["1.5.1"] = QList<FMLlib>{
-		{"argo-small-3.2.jar", "58912ea2858d168c50781f956fa5b59f0f7c6b51", false},
-		{"guava-14.0-rc3.jar", "931ae21fa8014c3ce686aaa621eae565fefb1a6a", false},
-		{"asm-all-4.1.jar", "054986e962b88d8660ae4566475658469595ef58", false},
-		{"bcprov-jdk15on-148.jar", "960dea7c9181ba0b17e8bab0c06a43f0a5f04e65", true},
-		{"deobfuscation_data_1.5.1.zip", "22e221a0d89516c1f721d6cab056a7e37471d0a6", false},
-		{"scala-library.jar", "458d046151ad179c85429ed7420ffb1eaf6ddf85", true}};
-
-	fmlLibsMapping["1.5.2"] = QList<FMLlib>{
-		{"argo-small-3.2.jar", "58912ea2858d168c50781f956fa5b59f0f7c6b51", false},
-		{"guava-14.0-rc3.jar", "931ae21fa8014c3ce686aaa621eae565fefb1a6a", false},
-		{"asm-all-4.1.jar", "054986e962b88d8660ae4566475658469595ef58", false},
-		{"bcprov-jdk15on-148.jar", "960dea7c9181ba0b17e8bab0c06a43f0a5f04e65", true},
-		{"deobfuscation_data_1.5.2.zip", "446e55cd986582c70fcf12cb27bc00114c5adfd9", false},
-		{"scala-library.jar", "458d046151ad179c85429ed7420ffb1eaf6ddf85", true}};
 }
 
 void LegacyUpdate::executeTask()
@@ -110,6 +68,7 @@ void LegacyUpdate::fmllibsStart()
 	bool forge_present = false;
 
 	QString version = inst->intendedVersionId();
+	auto & fmlLibsMapping = g_VersionFilterData.fmlLibsMapping;
 	if (!fmlLibsMapping.contains(version))
 	{
 		lwjglStart();
@@ -152,7 +111,7 @@ void LegacyUpdate::fmllibsStart()
 	// now check the lib folder inside the instance for files.
 	for (auto &lib : libList)
 	{
-		QFileInfo libInfo(PathCombine(inst->libDir(), lib.name));
+		QFileInfo libInfo(PathCombine(inst->libDir(), lib.filename));
 		if (libInfo.exists())
 			continue;
 		fmlLibsToProcess.append(lib);
@@ -171,9 +130,9 @@ void LegacyUpdate::fmllibsStart()
 	auto metacache = MMC->metacache();
 	for (auto &lib : fmlLibsToProcess)
 	{
-		auto entry = metacache->resolveEntry("fmllibs", lib.name);
-		QString urlString = lib.ours ? URLConstants::FMLLIBS_OUR_BASE_URL + lib.name
-									 : URLConstants::FMLLIBS_FORGE_BASE_URL + lib.name;
+		auto entry = metacache->resolveEntry("fmllibs", lib.filename);
+		QString urlString = lib.ours ? URLConstants::FMLLIBS_OUR_BASE_URL + lib.filename
+									 : URLConstants::FMLLIBS_FORGE_BASE_URL + lib.filename;
 		dljob->addNetAction(CacheDownload::make(QUrl(urlString), entry));
 	}
 
@@ -196,16 +155,16 @@ void LegacyUpdate::fmllibsFinished()
 		for (auto &lib : fmlLibsToProcess)
 		{
 			progress(index, fmlLibsToProcess.size());
-			auto entry = metacache->resolveEntry("fmllibs", lib.name);
-			auto path = PathCombine(inst->libDir(), lib.name);
+			auto entry = metacache->resolveEntry("fmllibs", lib.filename);
+			auto path = PathCombine(inst->libDir(), lib.filename);
 			if(!ensureFilePathExists(path))
 			{
 				emitFailed(tr("Failed creating FML library folder inside the instance."));
 				return;
 			}
-			if (!QFile::copy(entry->getFullPath(), PathCombine(inst->libDir(), lib.name)))
+			if (!QFile::copy(entry->getFullPath(), PathCombine(inst->libDir(), lib.filename)))
 			{
-				emitFailed(tr("Failed copying Forge/FML library: %1.").arg(lib.name));
+				emitFailed(tr("Failed copying Forge/FML library: %1.").arg(lib.filename));
 				return;
 			}
 			index++;
@@ -265,8 +224,6 @@ void LegacyUpdate::lwjglStart()
 	connect(rep, SIGNAL(downloadProgress(qint64, qint64)), SIGNAL(progress(qint64, qint64)));
 	connect(worker.get(), SIGNAL(finished(QNetworkReply *)),
 			SLOT(lwjglFinished(QNetworkReply *)));
-	// connect(rep, SIGNAL(error(QNetworkReply::NetworkError)),
-	// SLOT(downloadError(QNetworkReply::NetworkError)));
 }
 
 void LegacyUpdate::lwjglFinished(QNetworkReply *reply)
diff --git a/logic/LegacyUpdate.h b/logic/LegacyUpdate.h
index 5b073cb7..140ee1e3 100644
--- a/logic/LegacyUpdate.h
+++ b/logic/LegacyUpdate.h
@@ -21,19 +21,13 @@
 
 #include "logic/net/NetJob.h"
 #include "logic/tasks/Task.h"
+#include "logic/VersionFilterData.h"
 
 class MinecraftVersion;
 class BaseInstance;
 class QuaZip;
 class Mod;
 
-struct FMLlib
-{
-	QString name;
-	QString checksum;
-	bool ours;
-};
-
 class LegacyUpdate : public Task
 {
 	Q_OBJECT
@@ -84,5 +78,4 @@ private:
 	NetJobPtr legacyDownloadJob;
 	BaseInstance *m_inst = nullptr;
 	QList<FMLlib> fmlLibsToProcess;
-	QMap<QString, QList<FMLlib>> fmlLibsMapping;
 };
diff --git a/logic/lists/LwjglVersionList.cpp b/logic/LwjglVersionList.cpp
index df46d7be..df46d7be 100644
--- a/logic/lists/LwjglVersionList.cpp
+++ b/logic/LwjglVersionList.cpp
diff --git a/logic/lists/LwjglVersionList.h b/logic/LwjglVersionList.h
index fa57e8eb..fa57e8eb 100644
--- a/logic/lists/LwjglVersionList.h
+++ b/logic/LwjglVersionList.h
diff --git a/logic/MMCJson.cpp b/logic/MMCJson.cpp
index 65423436..8de88b6b 100644
--- a/logic/MMCJson.cpp
+++ b/logic/MMCJson.cpp
@@ -1,5 +1,6 @@
 #include "MMCJson.h"
 #include <QString>
+#include <QStringList>
 #include <math.h>
 
 bool MMCJson::ensureBoolean(const QJsonValue val, const QString what)
@@ -11,7 +12,7 @@ bool MMCJson::ensureBoolean(const QJsonValue val, const QString what)
 
 QJsonValue MMCJson::ensureExists(QJsonValue val, const QString what)
 {
-	if(val.isNull())
+	if(val.isUndefined() || val.isUndefined())
 		throw JSONValidationError(what + " does not exist");
 	return val;
 }
@@ -59,3 +60,24 @@ QString MMCJson::ensureString(const QJsonValue val, const QString what)
 	return val.toString();
 }
 
+void MMCJson::writeString(QJsonObject &to, QString key, QString value)
+{
+	if(value.size())
+	{
+		to.insert(key, value);
+	}
+}
+
+void MMCJson::writeStringList(QJsonObject &to, QString key, QStringList values)
+{
+	if(values.size())
+	{
+		QJsonArray array;
+		for(auto value: values)
+		{
+			array.append(value);
+		}
+		to.insert(key, array);
+	}
+}
+
diff --git a/logic/MMCJson.h b/logic/MMCJson.h
index 71ded435..8408f29b 100644
--- a/logic/MMCJson.h
+++ b/logic/MMCJson.h
@@ -43,4 +43,23 @@ int ensureInteger(const QJsonValue val, QString what = "value");
 
 /// make sure the value is converted into a double precision floating number. throw otherwise.
 double ensureDouble(const QJsonValue val, QString what = "value");
+
+void writeString(QJsonObject & to, QString key, QString value);
+
+void writeStringList (QJsonObject & to, QString key, QStringList values);
+
+template <typename T>
+void writeObjectList (QJsonObject & to, QString key, QList<T> values)
+{
+	if(values.size())
+	{
+		QJsonArray array;
+		for(auto value: values)
+		{
+			array.append(value->toJson());
+		}
+		to.insert(key, array);
+	}
+}
 }
+
diff --git a/logic/MinecraftProcess.cpp b/logic/MinecraftProcess.cpp
index b268a4cc..a3ffedba 100644
--- a/logic/MinecraftProcess.cpp
+++ b/logic/MinecraftProcess.cpp
@@ -71,6 +71,9 @@ MinecraftProcess::MinecraftProcess(InstancePtr inst) : m_instance(inst)
 		connect(&m_prepostlaunchprocess, &QProcess::readyReadStandardOutput, this,
 				&MinecraftProcess::on_prepost_stdOut);
 	}
+	
+	// a process has been constructed for the instance. It is running from MultiMC POV
+	m_instance->setRunning(true);
 }
 
 void MinecraftProcess::setWorkdir(QString path)
@@ -254,6 +257,8 @@ void MinecraftProcess::finish(int code, ExitStatus status)
 	// run post-exit
 	postLaunch();
 	m_instance->cleanupAfterRun();
+	// no longer running...
+	m_instance->setRunning(false);
 	emit ended(m_instance, code, status);
 }
 
@@ -304,6 +309,8 @@ bool MinecraftProcess::preLaunch()
 			m_instance->cleanupAfterRun();
 			emit prelaunch_failed(m_instance, m_prepostlaunchprocess.exitCode(),
 								  m_prepostlaunchprocess.exitStatus());
+			// not running, failed
+			m_instance->setRunning(false);
 			return false;
 		}
 		else
@@ -343,6 +350,8 @@ bool MinecraftProcess::postLaunch()
 					 MessageLevel::Error);
 			emit postlaunch_failed(m_instance, m_prepostlaunchprocess.exitCode(),
 								   m_prepostlaunchprocess.exitStatus());
+			// not running, failed
+			m_instance->setRunning(false);
 		}
 		else
 			emit log(tr("Post-Launch command ran successfully.\n\n"));
@@ -460,6 +469,8 @@ void MinecraftProcess::arm()
 		emit log(tr("Could not launch minecraft!"), MessageLevel::Error);
 		m_instance->cleanupAfterRun();
 		emit launch_failed(m_instance);
+		// not running, failed
+		m_instance->setRunning(false);
 		return;
 	}
 	// send the launch script to the launcher part
diff --git a/logic/MinecraftVersion.h b/logic/MinecraftVersion.h
deleted file mode 100644
index 504381a8..00000000
--- a/logic/MinecraftVersion.h
+++ /dev/null
@@ -1,89 +0,0 @@
-/* Copyright 2013 Andrew Okin
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#pragma once
-
-#include "BaseVersion.h"
-#include <QStringList>
-
-struct MinecraftVersion : public BaseVersion
-{
-	/*!
-	 * Gets the version's timestamp.
-	 * This is primarily used for sorting versions in a list.
-	 */
-	qint64 timestamp;
-
-	/// The URL that this version will be downloaded from. maybe.
-	QString download_url;
-
-	/// This version's type. Used internally to identify what kind of version this is.
-	enum VersionType
-	{
-		OneSix,
-		Legacy,
-		Nostalgia
-	} type;
-
-	/// is this the latest version?
-	bool is_latest = false;
-
-	/// is this a snapshot?
-	bool is_snapshot = false;
-
-	QString m_name;
-
-	QString m_descriptor;
-
-	virtual QString descriptor()
-	{
-		return m_descriptor;
-	}
-
-	virtual QString name()
-	{
-		return m_name;
-	}
-
-	virtual QString typeString() const
-	{
-		QStringList pre_final;
-		if (is_latest == true)
-		{
-			pre_final.append("Latest");
-		}
-		switch (type)
-		{
-		case OneSix:
-			pre_final.append("OneSix");
-			break;
-		case Legacy:
-			pre_final.append("Legacy");
-			break;
-		case Nostalgia:
-			pre_final.append("Nostalgia");
-			break;
-
-		default:
-			pre_final.append(QString("Type(%1)").arg(type));
-			break;
-		}
-		if (is_snapshot == true)
-		{
-			pre_final.append("Snapshot");
-		}
-		return pre_final.join(' ');
-	}
-};
diff --git a/logic/ModList.cpp b/logic/ModList.cpp
index 79b56986..f7770920 100644
--- a/logic/ModList.cpp
+++ b/logic/ModList.cpp
@@ -26,6 +26,7 @@
 ModList::ModList(const QString &dir, const QString &list_file)
 	: QAbstractListModel(), m_dir(dir), m_list_file(list_file)
 {
+	ensureFolderPathExists(m_dir.absolutePath());
 	m_dir.setFilter(QDir::Readable | QDir::NoDotAndDotDot | QDir::Files | QDir::Dirs |
 					QDir::NoSymLinks);
 	m_dir.setSorting(QDir::Name | QDir::IgnoreCase | QDir::LocaleAware);
diff --git a/logic/NostalgiaInstance.cpp b/logic/NostalgiaInstance.cpp
deleted file mode 100644
index 52820725..00000000
--- a/logic/NostalgiaInstance.cpp
+++ /dev/null
@@ -1,36 +0,0 @@
-/* Copyright 2013 MultiMC Contributors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include "NostalgiaInstance.h"
-
-NostalgiaInstance::NostalgiaInstance(const QString &rootDir, SettingsObject *settings,
-									 QObject *parent)
-	: OneSixInstance(rootDir, settings, parent)
-{
-}
-
-QString NostalgiaInstance::getStatusbarDescription()
-{
-	if (flags().contains(VersionBrokenFlag))
-	{
-		return "Nostalgia : " + intendedVersionId() + " (broken)";
-	}
-	return "Nostalgia : " + intendedVersionId();
-}
-
-bool NostalgiaInstance::menuActionEnabled(QString action_name) const
-{
-	return false;
-}
diff --git a/logic/NostalgiaInstance.h b/logic/NostalgiaInstance.h
deleted file mode 100644
index f95531d2..00000000
--- a/logic/NostalgiaInstance.h
+++ /dev/null
@@ -1,29 +0,0 @@
-/* Copyright 2013 MultiMC Contributors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#pragma once
-
-#include "OneSixInstance.h"
-
-class NostalgiaInstance : public OneSixInstance
-{
-	Q_OBJECT
-public:
-	explicit NostalgiaInstance(const QString &rootDir, SettingsObject *settings,
-							   QObject *parent = 0);
-	virtual ~NostalgiaInstance() {};
-	virtual QString getStatusbarDescription();
-	virtual bool menuActionEnabled(QString action_name) const;
-};
diff --git a/logic/OneSixFTBInstance.cpp b/logic/OneSixFTBInstance.cpp
index 172830bb..ef951987 100644
--- a/logic/OneSixFTBInstance.cpp
+++ b/logic/OneSixFTBInstance.cpp
@@ -1,12 +1,12 @@
 #include "OneSixFTBInstance.h"
 
-#include "VersionFinal.h"
-#include "OneSixLibrary.h"
+#include "logic/minecraft/InstanceVersion.h"
+#include "logic/minecraft/OneSixLibrary.h"
+#include "logic/minecraft/VersionBuilder.h"
 #include "tasks/SequentialTask.h"
-#include "ForgeInstaller.h"
-#include "lists/ForgeVersionList.h"
+#include "forge/ForgeInstaller.h"
+#include "forge/ForgeVersionList.h"
 #include "OneSixInstance_p.h"
-#include "OneSixVersionBuilder.h"
 #include "MultiMC.h"
 #include "pathutils.h"
 
@@ -100,6 +100,7 @@ QDir OneSixFTBInstance::librariesPath() const
 {
 	return QDir(MMC->settings()->get("FTBRoot").toString() + "/libraries");
 }
+
 QDir OneSixFTBInstance::versionsPath() const
 {
 	return QDir(MMC->settings()->get("FTBRoot").toString() + "/versions");
@@ -107,7 +108,6 @@ QDir OneSixFTBInstance::versionsPath() const
 
 QStringList OneSixFTBInstance::externalPatches() const
 {
-	I_D(OneSixInstance);
 	return QStringList() << versionsPath().absoluteFilePath(intendedVersionId() + "/" + intendedVersionId() + ".json")
 						 << minecraftRoot() + "/pack.json";
 }
@@ -125,10 +125,6 @@ QString OneSixFTBInstance::getStatusbarDescription()
 	}
 	return "OneSix FTB: " + intendedVersionId();
 }
-bool OneSixFTBInstance::menuActionEnabled(QString action_name) const
-{
-	return false;
-}
 
 std::shared_ptr<Task> OneSixFTBInstance::doUpdate()
 {
diff --git a/logic/OneSixFTBInstance.h b/logic/OneSixFTBInstance.h
index 440dc9f1..ecfa2231 100644
--- a/logic/OneSixFTBInstance.h
+++ b/logic/OneSixFTBInstance.h
@@ -16,7 +16,6 @@ public:
 	void copy(const QDir &newDir) override;
 
 	virtual QString getStatusbarDescription();
-	virtual bool menuActionEnabled(QString action_name) const;
 
 	virtual std::shared_ptr<Task> doUpdate() override;
 
diff --git a/logic/OneSixInstance.cpp b/logic/OneSixInstance.cpp
index 6f3018cb..7bac3424 100644
--- a/logic/OneSixInstance.cpp
+++ b/logic/OneSixInstance.cpp
@@ -13,52 +13,84 @@
  * limitations under the License.
  */
 
-#include "OneSixInstance.h"
-
 #include <QIcon>
-
-#include "OneSixInstance_p.h"
-#include "OneSixUpdate.h"
-#include "VersionFinal.h"
-#include "pathutils.h"
+#include <pathutils.h>
 #include "logger/QsLog.h"
-#include "assets/AssetsUtils.h"
 #include "MultiMC.h"
-#include "icons/IconList.h"
-#include "MinecraftProcess.h"
-#include "gui/dialogs/OneSixModEditDialog.h"
-#include <MMCError.h>
+#include "MMCError.h"
+
+#include "logic/OneSixInstance.h"
 
-OneSixInstance::OneSixInstance(const QString &rootDir, SettingsObject *settings, QObject *parent)
+#include "logic/OneSixInstance_p.h"
+#include "logic/OneSixUpdate.h"
+#include "logic/minecraft/InstanceVersion.h"
+#include "minecraft/VersionBuildError.h"
+
+#include "logic/assets/AssetsUtils.h"
+#include "icons/IconList.h"
+#include "logic/MinecraftProcess.h"
+#include "gui/pagedialog/PageDialog.h"
+#include "gui/pages/VersionPage.h"
+#include <gui/pages/ModFolderPage.h>
+#include <gui/pages/ResourcePackPage.h>
+#include <gui/pages/TexturePackPage.h>
+#include <gui/pages/InstanceSettingsPage.h>
+#include <gui/pages/NotesPage.h>
+#include <gui/pages/ScreenshotsPage.h>
+
+OneSixInstance::OneSixInstance(const QString &rootDir, SettingsObject *settings,
+							   QObject *parent)
 	: BaseInstance(new OneSixInstancePrivate(), rootDir, settings, parent)
 {
 	I_D(OneSixInstance);
 	d->m_settings->registerSetting("IntendedVersion", "");
-	d->m_settings->registerSetting("ShouldUpdate", false);
-	d->version.reset(new VersionFinal(this, this));
-	d->vanillaVersion.reset(new VersionFinal(this, this));
+	d->version.reset(new InstanceVersion(this, this));
 }
 
 void OneSixInstance::init()
 {
-	// FIXME: why is this decided here? what does this even mean?
-	if (QDir(instanceRoot()).exists("version.json"))
+	try
 	{
-		try
-		{
-			reloadVersion();
-		}
-		catch(MMCError & e)
-		{
-			// QLOG_ERROR() << "Caught exception on instance init: " << e.cause();
-		}
+		reloadVersion();
 	}
-	else
+	catch (MMCError &e)
 	{
-		clearVersion();
+		QLOG_ERROR() << "Caught exception on instance init: " << e.cause();
 	}
 }
 
+QList<BasePage *> OneSixInstance::getPages()
+{
+	QList<BasePage *> values;
+	values.append(new VersionPage(this));
+	values.append(new ModFolderPage(this, loaderModList(), "mods", "plugin-blue", tr("Loader mods"),
+									"Loader-mods"));
+	values.append(new ModFolderPage(this, coreModList(), "coremods", "plugin-green", tr("Core mods"),
+									"Core-mods"));
+	values.append(new ResourcePackPage(this));
+	values.append(new TexturePackPage(this));
+	values.append(new NotesPage(this));
+	values.append(new ScreenshotsPage(this));
+	values.append(new InstanceSettingsPage(this));
+	return values;
+}
+
+QString OneSixInstance::dialogTitle()
+{
+	return tr("Edit Instance (%1)").arg(name());
+}
+
+QSet<QString> OneSixInstance::traits()
+{
+	auto version = getFullVersion();
+	if (!version)
+	{
+		return {"version-incomplete"};
+	}
+	else
+		return version->traits;
+}
+
 std::shared_ptr<Task> OneSixInstance::doUpdate()
 {
 	return std::shared_ptr<Task>(new OneSixUpdate(this));
@@ -88,7 +120,7 @@ QString replaceTokensIn(QString text, QMap<QString, QString> with)
 	return result;
 }
 
-QDir OneSixInstance::reconstructAssets(std::shared_ptr<VersionFinal> version)
+QDir OneSixInstance::reconstructAssets(std::shared_ptr<InstanceVersion> version)
 {
 	QDir assetsDir = QDir("assets/");
 	QDir indexDir = QDir(PathCombine(assetsDir.path(), "indexes"));
@@ -126,7 +158,7 @@ QDir OneSixInstance::reconstructAssets(std::shared_ptr<VersionFinal> version)
 			QString original_path =
 				PathCombine(PathCombine(objectDir.path(), tlk), asset_object.hash);
 			QFile original(original_path);
-			if(!original.exists())
+			if (!original.exists())
 				continue;
 			if (!target.exists())
 			{
@@ -138,7 +170,7 @@ QDir OneSixInstance::reconstructAssets(std::shared_ptr<VersionFinal> version)
 
 				bool couldCopy = original.copy(target_path);
 				QLOG_DEBUG() << " Copying" << original_path << "to" << target_path
-								<< QString::number(couldCopy); // << original.errorString();
+							 << QString::number(couldCopy); // << original.errorString();
 			}
 		}
 
@@ -189,7 +221,7 @@ QStringList OneSixInstance::processMinecraftArgs(AuthSessionPtr session)
 	return parts;
 }
 
-bool OneSixInstance::prepareForLaunch(AuthSessionPtr account, QString &launchScript)
+bool OneSixInstance::prepareForLaunch(AuthSessionPtr session, QString &launchScript)
 {
 	I_D(OneSixInstance);
 
@@ -200,44 +232,79 @@ bool OneSixInstance::prepareForLaunch(AuthSessionPtr account, QString &launchScr
 	auto version = d->version;
 	if (!version)
 		return nullptr;
+
+	// libraries and class path.
 	{
 		auto libs = version->getActiveNormalLibs();
 		for (auto lib : libs)
 		{
 			launchScript += "cp " + librariesPath().absoluteFilePath(lib->storagePath()) + "\n";
 		}
-		QString targetstr = version->id + "/" + version->id + ".jar";
-		launchScript += "cp " + versionsPath().absoluteFilePath(targetstr) + "\n";
+		QString minecraftjarpath;
+		if (version->hasJarMods())
+		{
+			for (auto jarmod : version->jarMods)
+			{
+				launchScript += "cp " + jarmodsPath().absoluteFilePath(jarmod->name) + "\n";
+			}
+			minecraftjarpath = version->id + "/" + version->id + "-stripped.jar";
+		}
+		else
+		{
+			minecraftjarpath = version->id + "/" + version->id + ".jar";
+		}
+		launchScript += "cp " + versionsPath().absoluteFilePath(minecraftjarpath) + "\n";
+	}
+	if (!version->mainClass.isEmpty())
+	{
+		launchScript += "mainClass " + version->mainClass + "\n";
+	}
+	if (!version->appletClass.isEmpty())
+	{
+		launchScript += "appletClass " + version->appletClass + "\n";
 	}
-	launchScript += "mainClass " + version->mainClass + "\n";
 
-	for (auto param : processMinecraftArgs(account))
+	// generic minecraft params
+	for (auto param : processMinecraftArgs(session))
 	{
 		launchScript += "param " + param + "\n";
 	}
 
-	// Set the width and height for 1.6 instances
-	bool maximize = settings().get("LaunchMaximized").toBool();
-	if (maximize)
+	// window size, title and state, legacy
 	{
-		// this is probably a BAD idea
-		// launchScript += "param --fullscreen\n";
+		QString windowParams;
+		if (settings().get("LaunchMaximized").toBool())
+			windowParams = "max";
+		else
+			windowParams = QString("%1x%2")
+							   .arg(settings().get("MinecraftWinWidth").toInt())
+							   .arg(settings().get("MinecraftWinHeight").toInt());
+		launchScript += "windowTitle " + windowTitle() + "\n";
+		launchScript += "windowParams " + windowParams + "\n";
 	}
-	else
+
+	// legacy auth
+	{
+		launchScript += "userName " + session->player_name + "\n";
+		launchScript += "sessionId " + session->session + "\n";
+	}
+
+	// native libraries (mostly LWJGL)
 	{
-		launchScript +=
-			"param --width\nparam " + settings().get("MinecraftWinWidth").toString() + "\n";
-		launchScript +=
-			"param --height\nparam " + settings().get("MinecraftWinHeight").toString() + "\n";
+		QDir natives_dir(PathCombine(instanceRoot(), "natives/"));
+		for (auto native : version->getActiveNativeLibs())
+		{
+			QFileInfo finfo(PathCombine("libraries", native->storagePath()));
+			launchScript += "ext " + finfo.absoluteFilePath() + "\n";
+		}
+		launchScript += "natives " + natives_dir.absolutePath() + "\n";
 	}
-	QDir natives_dir(PathCombine(instanceRoot(), "natives/"));
-	launchScript += "windowTitle " + windowTitle() + "\n";
-	for(auto native: version->getActiveNativeLibs())
+
+	// traits. including legacyLaunch and others ;)
+	for (auto trait : version->traits)
 	{
-		QFileInfo finfo(PathCombine("libraries", native->storagePath()));
-		launchScript += "ext " + finfo.absoluteFilePath() + "\n";
+		launchScript += "traits " + trait + "\n";
 	}
-	launchScript += "natives " + natives_dir.absolutePath() + "\n";
 	launchScript += "launcher onesix\n";
 	return true;
 }
@@ -260,6 +327,17 @@ std::shared_ptr<ModList> OneSixInstance::loaderModList()
 	return d->loader_mod_list;
 }
 
+std::shared_ptr<ModList> OneSixInstance::coreModList()
+{
+	I_D(OneSixInstance);
+	if (!d->core_mod_list)
+	{
+		d->core_mod_list.reset(new ModList(coreModsDir()));
+	}
+	d->core_mod_list->update();
+	return d->core_mod_list;
+}
+
 std::shared_ptr<ModList> OneSixInstance::resourcePackList()
 {
 	I_D(OneSixInstance);
@@ -271,15 +349,20 @@ std::shared_ptr<ModList> OneSixInstance::resourcePackList()
 	return d->resource_pack_list;
 }
 
-QDialog *OneSixInstance::createModEditDialog(QWidget *parent)
+std::shared_ptr<ModList> OneSixInstance::texturePackList()
 {
-	return new OneSixModEditDialog(this, parent);
+	I_D(OneSixInstance);
+	if (!d->texture_pack_list)
+	{
+		d->texture_pack_list.reset(new ModList(texturePacksDir()));
+	}
+	d->texture_pack_list->update();
+	return d->texture_pack_list;
 }
 
 bool OneSixInstance::setIntendedVersionId(QString version)
 {
 	settings().set("IntendedVersion", version);
-	setShouldUpdate(true);
 	QFile::remove(PathCombine(instanceRoot(), "version.json"));
 	clearVersion();
 	return true;
@@ -290,34 +373,31 @@ QString OneSixInstance::intendedVersionId() const
 	return settings().get("IntendedVersion").toString();
 }
 
-void OneSixInstance::setShouldUpdate(bool val)
+void OneSixInstance::setShouldUpdate(bool)
 {
-	settings().set("ShouldUpdate", val);
 }
 
 bool OneSixInstance::shouldUpdate() const
 {
-	QVariant var = settings().get("ShouldUpdate");
-	if (!var.isValid() || var.toBool() == false)
-	{
-		return intendedVersionId() != currentVersionId();
-	}
 	return true;
 }
 
 bool OneSixInstance::versionIsCustom()
 {
-	QDir patches(PathCombine(instanceRoot(), "patches/"));
-	return (patches.exists() && patches.count() >= 0)
-			|| QFile::exists(PathCombine(instanceRoot(), "custom.json"))
-			|| QFile::exists(PathCombine(instanceRoot(), "user.json"));
+	I_D(const OneSixInstance);
+	auto ver = d->version;
+	if (ver)
+	{
+		return !ver->isVanilla();
+	}
+	return false;
 }
 
 bool OneSixInstance::versionIsFTBPack()
 {
 	I_D(const OneSixInstance);
 	auto ver = d->version;
-	if(ver)
+	if (ver)
 	{
 		return ver->hasFtbPack();
 	}
@@ -335,17 +415,18 @@ void OneSixInstance::reloadVersion()
 
 	try
 	{
-		d->version->reload(false, externalPatches());
-		d->vanillaVersion->reload(true, externalPatches());
+		d->version->reload(externalPatches());
 		d->m_flags.remove(VersionBrokenFlag);
 		emit versionReloaded();
 	}
-	catch(MMCError & error)
+	catch (VersionIncomplete &error)
+	{
+	}
+	catch (MMCError &error)
 	{
 		d->version->clear();
-		d->vanillaVersion->clear();
 		d->m_flags.insert(VersionBrokenFlag);
-		//TODO: rethrow to show some error message(s)?
+		// TODO: rethrow to show some error message(s)?
 		emit versionReloaded();
 		throw;
 	}
@@ -355,22 +436,15 @@ void OneSixInstance::clearVersion()
 {
 	I_D(OneSixInstance);
 	d->version->clear();
-	d->vanillaVersion->clear();
 	emit versionReloaded();
 }
 
-std::shared_ptr<VersionFinal> OneSixInstance::getFullVersion() const
+std::shared_ptr<InstanceVersion> OneSixInstance::getFullVersion() const
 {
 	I_D(const OneSixInstance);
 	return d->version;
 }
 
-std::shared_ptr<VersionFinal> OneSixInstance::getVanillaVersion() const
-{
-	I_D(const OneSixInstance);
-	return d->vanillaVersion;
-}
-
 QString OneSixInstance::defaultBaseJar() const
 {
 	return "versions/" + intendedVersionId() + "/" + intendedVersionId() + ".jar";
@@ -381,37 +455,38 @@ QString OneSixInstance::defaultCustomBaseJar() const
 	return PathCombine(instanceRoot(), "custom.jar");
 }
 
-bool OneSixInstance::menuActionEnabled(QString action_name) const
+QString OneSixInstance::getStatusbarDescription()
 {
-	if (flags().contains(VersionBrokenFlag))
+	QStringList traits;
+	if (versionIsCustom())
 	{
-		return false;
+		traits.append(tr("custom"));
 	}
-	if (action_name == "actionChangeInstLWJGLVersion")
+	if (flags().contains(VersionBrokenFlag))
 	{
-		return false;
+		traits.append(tr("broken"));
 	}
-	return true;
-}
 
-QString OneSixInstance::getStatusbarDescription()
-{
-	QString descr = "OneSix : " + intendedVersionId();
-	if (versionIsCustom())
+	if (traits.size())
 	{
-		descr += " (custom)";
+		return tr("Minecraft %1 (%2)").arg(intendedVersionId()).arg(traits.join(", "));
 	}
-	if (flags().contains(VersionBrokenFlag))
+	else
 	{
-		descr += " (broken)";
+		return tr("Minecraft %1").arg(intendedVersionId());
 	}
-	return descr;
 }
 
 QDir OneSixInstance::librariesPath() const
 {
 	return QDir::current().absoluteFilePath("libraries");
 }
+
+QDir OneSixInstance::jarmodsPath() const
+{
+	return QDir(jarModsDir());
+}
+
 QDir OneSixInstance::versionsPath() const
 {
 	return QDir::current().absoluteFilePath("versions");
@@ -429,7 +504,7 @@ bool OneSixInstance::providesVersionFile() const
 
 bool OneSixInstance::reload()
 {
-	if(BaseInstance::reload())
+	if (BaseInstance::reload())
 	{
 		try
 		{
@@ -449,12 +524,46 @@ QString OneSixInstance::loaderModsDir() const
 	return PathCombine(minecraftRoot(), "mods");
 }
 
+QString OneSixInstance::coreModsDir() const
+{
+	return PathCombine(minecraftRoot(), "coremods");
+}
+
 QString OneSixInstance::resourcePacksDir() const
 {
 	return PathCombine(minecraftRoot(), "resourcepacks");
 }
 
+QString OneSixInstance::texturePacksDir() const
+{
+	return PathCombine(minecraftRoot(), "texturepacks");
+}
+
 QString OneSixInstance::instanceConfigFolder() const
 {
 	return PathCombine(minecraftRoot(), "config");
 }
+
+QString OneSixInstance::jarModsDir() const
+{
+	return PathCombine(instanceRoot(), "jarmods");
+}
+
+QString OneSixInstance::libDir() const
+{
+	return PathCombine(minecraftRoot(), "lib");
+}
+
+QStringList OneSixInstance::extraArguments() const
+{
+	auto list = BaseInstance::extraArguments();
+	auto version = getFullVersion();
+	if (!version)
+		return list;
+	if (version->hasJarMods())
+	{
+		list.append({"-Dfml.ignoreInvalidMinecraftCertificates=true",
+					 "-Dfml.ignorePatchDiscrepancies=true"});
+	}
+	return list;
+}
diff --git a/logic/OneSixInstance.h b/logic/OneSixInstance.h
index 13a392c2..75caef1f 100644
--- a/logic/OneSixInstance.h
+++ b/logic/OneSixInstance.h
@@ -17,10 +17,11 @@
 
 #include "BaseInstance.h"
 
-#include "VersionFinal.h"
-#include "ModList.h"
+#include "logic/minecraft/InstanceVersion.h"
+#include "logic/ModList.h"
+#include "gui/pages/BasePageProvider.h"
 
-class OneSixInstance : public BaseInstance
+class OneSixInstance : public BaseInstance, public BasePageProvider
 {
 	Q_OBJECT
 public:
@@ -30,13 +31,25 @@ public:
 
 	virtual void init() override;
 
+	////// Edit Instance Dialog stuff //////
+	virtual QList<BasePage *> getPages();
+	virtual QString dialogTitle();
+
 	//////  Mod Lists  //////
 	std::shared_ptr<ModList> loaderModList();
-	std::shared_ptr<ModList> resourcePackList();
-
-	////// Directories //////
+	std::shared_ptr<ModList> coreModList();
+	std::shared_ptr<ModList> resourcePackList() override;
+	std::shared_ptr<ModList> texturePackList() override;
+
+	virtual QSet<QString> traits();
+	
+	////// Directories and files //////
+	QString jarModsDir() const;
 	QString resourcePacksDir() const;
+	QString texturePacksDir() const;
 	QString loaderModsDir() const;
+	QString coreModsDir() const;
+	QString libDir() const;
 	virtual QString instanceConfigFolder() const override;
 
 	virtual std::shared_ptr<Task> doUpdate() override;
@@ -52,42 +65,43 @@ public:
 	virtual bool shouldUpdate() const override;
 	virtual void setShouldUpdate(bool val) override;
 
-	virtual QDialog *createModEditDialog(QWidget *parent) override;
-
 	/**
-	 * reload the full version json files. return true on success!
+	 * reload the full version json files.
 	 * 
 	 * throws various exceptions :3
 	 */
 	void reloadVersion();
+	
 	/// clears all version information in preparation for an update
 	void clearVersion();
+	
 	/// get the current full version info
-	std::shared_ptr<VersionFinal> getFullVersion() const;
-	/// gets the current version info, but only for version.json
-	std::shared_ptr<VersionFinal> getVanillaVersion() const;
+	std::shared_ptr<InstanceVersion> getFullVersion() const;
+	
 	/// is the current version original, or custom?
 	virtual bool versionIsCustom() override;
+	
 	/// does this instance have an FTB pack patch inside?
 	bool versionIsFTBPack();
 
 	virtual QString defaultBaseJar() const override;
 	virtual QString defaultCustomBaseJar() const override;
 
-	virtual bool menuActionEnabled(QString action_name) const override;
 	virtual QString getStatusbarDescription() override;
 
+	virtual QDir jarmodsPath() const;
 	virtual QDir librariesPath() const;
 	virtual QDir versionsPath() const;
 	virtual QStringList externalPatches() const;
 	virtual bool providesVersionFile() const;
 
 	bool reload() override;
-
+	virtual QStringList extraArguments() const override;
+	
 signals:
 	void versionReloaded();
 
 private:
 	QStringList processMinecraftArgs(AuthSessionPtr account);
-	QDir reconstructAssets(std::shared_ptr<VersionFinal> version);
+	QDir reconstructAssets(std::shared_ptr<InstanceVersion> version);
 };
diff --git a/logic/OneSixInstance_p.h b/logic/OneSixInstance_p.h
index c70de07c..3c4ef324 100644
--- a/logic/OneSixInstance_p.h
+++ b/logic/OneSixInstance_p.h
@@ -15,16 +15,19 @@
 
 #pragma once
 
-#include "BaseInstance_p.h"
-#include "VersionFinal.h"
-#include "ModList.h"
+#include "logic/BaseInstance_p.h"
+
+class ModList;
+class InstanceVersion;
 
 class OneSixInstancePrivate : public BaseInstancePrivate
 {
 public:
 	virtual ~OneSixInstancePrivate() {};
-	std::shared_ptr<VersionFinal> version;
-	std::shared_ptr<VersionFinal> vanillaVersion;
+	std::shared_ptr<InstanceVersion> version;
+	std::shared_ptr<ModList> jar_mod_list;
 	std::shared_ptr<ModList> loader_mod_list;
+	std::shared_ptr<ModList> core_mod_list;
 	std::shared_ptr<ModList> resource_pack_list;
+	std::shared_ptr<ModList> texture_pack_list;
 };
diff --git a/logic/OneSixUpdate.cpp b/logic/OneSixUpdate.cpp
index d083c2ba..abc5f9c1 100644
--- a/logic/OneSixUpdate.cpp
+++ b/logic/OneSixUpdate.cpp
@@ -22,28 +22,24 @@
 #include <QFileInfo>
 #include <QTextStream>
 #include <QDataStream>
-
-#include "BaseInstance.h"
-#include "lists/MinecraftVersionList.h"
-#include "VersionFinal.h"
-#include "OneSixLibrary.h"
-#include "OneSixInstance.h"
-#include "net/ForgeMirrors.h"
-#include "net/URLConstants.h"
-#include "assets/AssetsUtils.h"
-
-#include "pathutils.h"
+#include <pathutils.h>
 #include <JlCompress.h>
 
-OneSixUpdate::OneSixUpdate(OneSixInstance *inst, QObject *parent)
-	: Task(parent), m_inst(inst)
+#include "logic/BaseInstance.h"
+#include "logic/minecraft/MinecraftVersionList.h"
+#include "logic/minecraft/InstanceVersion.h"
+#include "logic/minecraft/OneSixLibrary.h"
+#include "logic/OneSixInstance.h"
+#include "logic/forge/ForgeMirrors.h"
+#include "logic/net/URLConstants.h"
+#include "logic/assets/AssetsUtils.h"
+
+OneSixUpdate::OneSixUpdate(OneSixInstance *inst, QObject *parent) : Task(parent), m_inst(inst)
 {
 }
 
 void OneSixUpdate::executeTask()
 {
-	QString intendedVersion = m_inst->intendedVersionId();
-
 	// Make directories
 	QDir mcDir(m_inst->minecraftRoot());
 	if (!mcDir.exists() && !mcDir.mkpath("."))
@@ -52,102 +48,44 @@ void OneSixUpdate::executeTask()
 		return;
 	}
 
-	if (m_inst->shouldUpdate())
+	// Get a pointer to the version object that corresponds to the instance's version.
+	targetVersion = std::dynamic_pointer_cast<MinecraftVersion>(
+		MMC->minecraftlist()->findVersion(m_inst->intendedVersionId()));
+	if (targetVersion == nullptr)
 	{
-		// Get a pointer to the version object that corresponds to the instance's version.
-		targetVersion = std::dynamic_pointer_cast<MinecraftVersion>(
-			MMC->minecraftlist()->findVersion(intendedVersion));
-		if (targetVersion == nullptr)
-		{
-			// don't do anything if it was invalid
-			emitFailed(tr("The specified Minecraft version is invalid. Choose a different one."));
-			return;
-		}
-		versionFileStart();
+		// don't do anything if it was invalid
+		emitFailed(tr("The specified Minecraft version is invalid. Choose a different one."));
+		return;
 	}
-	else
+	if (m_inst->providesVersionFile() || !targetVersion->needsUpdate())
 	{
 		jarlibStart();
+		return;
 	}
-}
-
-void OneSixUpdate::versionFileStart()
-{
-	if (m_inst->providesVersionFile())
+	versionUpdateTask = MMC->minecraftlist()->createUpdateTask(m_inst->intendedVersionId());
+	if (!versionUpdateTask)
 	{
 		jarlibStart();
 		return;
 	}
-	QLOG_INFO() << m_inst->name() << ": getting version file.";
-	setStatus(tr("Getting the version files from Mojang..."));
-
-	QString urlstr = "http://" + URLConstants::AWS_DOWNLOAD_VERSIONS +
-					 targetVersion->descriptor() + "/" + targetVersion->descriptor() + ".json";
-	auto job = new NetJob("Version index");
-	job->addNetAction(ByteArrayDownload::make(QUrl(urlstr)));
-	specificVersionDownloadJob.reset(job);
-	connect(specificVersionDownloadJob.get(), SIGNAL(succeeded()), SLOT(versionFileFinished()));
-	connect(specificVersionDownloadJob.get(), SIGNAL(failed()), SLOT(versionFileFailed()));
-	connect(specificVersionDownloadJob.get(), SIGNAL(progress(qint64, qint64)),
+	connect(versionUpdateTask.get(), SIGNAL(succeeded()), SLOT(jarlibStart()));
+	connect(versionUpdateTask.get(), SIGNAL(failed(QString)), SLOT(versionUpdateFailed(QString)));
+	connect(versionUpdateTask.get(), SIGNAL(progress(qint64, qint64)),
 			SIGNAL(progress(qint64, qint64)));
-	specificVersionDownloadJob->start();
-}
-
-void OneSixUpdate::versionFileFinished()
-{
-	NetActionPtr DlJob = specificVersionDownloadJob->first();
-
-	QString version_id = targetVersion->descriptor();
-	QString inst_dir = m_inst->instanceRoot();
-	// save the version file in $instanceId/version.json
-	{
-		QString version1 = PathCombine(inst_dir, "/version.json");
-		ensureFilePathExists(version1);
-		// FIXME: detect errors here, download to a temp file, swap
-		QSaveFile vfile1(version1);
-		if (!vfile1.open(QIODevice::Truncate | QIODevice::WriteOnly))
-		{
-			emitFailed(tr("Can't open %1 for writing.").arg(version1));
-			return;
-		}
-		auto data = std::dynamic_pointer_cast<ByteArrayDownload>(DlJob)->m_data;
-		qint64 actual = 0;
-		if ((actual = vfile1.write(data)) != data.size())
-		{
-			emitFailed(tr("Failed to write into %1. Written %2 out of %3.").arg(version1).arg(actual).arg(data.size()));
-			return;
-		}
-		if (!vfile1.commit())
-		{
-			emitFailed(tr("Can't commit changes to %1").arg(version1));
-			return;
-		}
-	}
-
-	// the version is downloaded safely. update is 'done' at this point
-	m_inst->setShouldUpdate(false);
-
-	// delete any custom version inside the instance (it's no longer relevant, we did an update)
-	QString custom = PathCombine(inst_dir, "/custom.json");
-	QFile finfo(custom);
-	if (finfo.exists())
-	{
-		finfo.remove();
-	}
-	// NOTE: Version is reloaded in jarlibStart
-	jarlibStart();
+	setStatus(tr("Getting the version files from Mojang..."));
+	versionUpdateTask->start();
 }
 
-void OneSixUpdate::versionFileFailed()
+void OneSixUpdate::versionUpdateFailed(QString reason)
 {
-	emitFailed(tr("Failed to download the version description. Try again."));
+	emitFailed(reason);
 }
 
 void OneSixUpdate::assetIndexStart()
 {
 	setStatus(tr("Updating assets index..."));
 	OneSixInstance *inst = (OneSixInstance *)m_inst;
-	std::shared_ptr<VersionFinal> version = inst->getFullVersion();
+	std::shared_ptr<InstanceVersion> version = inst->getFullVersion();
 	QString assetName = version->assets;
 	QUrl indexUrl = "http://" + URLConstants::AWS_DOWNLOAD_INDEXES + assetName + ".json";
 	QString localPath = assetName + ".json";
@@ -171,7 +109,7 @@ void OneSixUpdate::assetIndexFinished()
 	AssetsIndex index;
 
 	OneSixInstance *inst = (OneSixInstance *)m_inst;
-	std::shared_ptr<VersionFinal> version = inst->getFullVersion();
+	std::shared_ptr<InstanceVersion> version = inst->getFullVersion();
 	QString assetName = version->assets;
 
 	QString asset_fname = "assets/indexes/" + assetName + ".json";
@@ -235,19 +173,19 @@ void OneSixUpdate::jarlibStart()
 	{
 		inst->reloadVersion();
 	}
-	catch(MMCError & e)
+	catch (MMCError &e)
 	{
 		emitFailed(e.cause());
 		return;
 	}
-	catch(...)
+	catch (...)
 	{
 		emitFailed(tr("Failed to load the version description file for reasons unknown."));
 		return;
 	}
 
 	// Build a list of URLs that will need to be downloaded.
-	std::shared_ptr<VersionFinal> version = inst->getFullVersion();
+	std::shared_ptr<InstanceVersion> version = inst->getFullVersion();
 	// minecraft.jar for this version
 	{
 		QString version_id = version->id;
@@ -259,7 +197,7 @@ void OneSixUpdate::jarlibStart()
 		auto metacache = MMC->metacache();
 		auto entry = metacache->resolveEntry("versions", localPath);
 		job->addNetAction(CacheDownload::make(QUrl(urlstr), entry));
-
+		jarHashOnEntry = entry->md5sum;
 		jarlibDownloadJob.reset(job);
 	}
 
@@ -274,7 +212,7 @@ void OneSixUpdate::jarlibStart()
 	{
 		if (lib->hint() == "local")
 		{
-			if(!lib->filesExist(m_inst->librariesPath()))
+			if (!lib->filesExist(m_inst->librariesPath()))
 				brokenLocalLibs.append(lib);
 			continue;
 		}
@@ -311,16 +249,19 @@ void OneSixUpdate::jarlibStart()
 			f(raw_storage, raw_dl);
 		}
 	}
-	if(!brokenLocalLibs.empty())
+	if (!brokenLocalLibs.empty())
 	{
 		jarlibDownloadJob.reset();
 		QStringList failed;
-		for(auto brokenLib : brokenLocalLibs)
+		for (auto brokenLib : brokenLocalLibs)
 		{
 			failed.append(brokenLib->files());
 		}
 		QString failed_all = failed.join("\n");
-		emitFailed(tr("Some libraries marked as 'local' are missing their jar files:\n%1\n\nYou'll have to correct this problem manually. If this is an externally tracked instance, make sure to run it at least once outside of MultiMC.").arg(failed_all));
+		emitFailed(tr("Some libraries marked as 'local' are missing their jar "
+					  "files:\n%1\n\nYou'll have to correct this problem manually. If this is "
+					  "an externally tracked instance, make sure to run it at least once "
+					  "outside of MultiMC.").arg(failed_all));
 		return;
 	}
 	// TODO: think about how to propagate this from the original json file... or IF AT ALL
@@ -341,12 +282,222 @@ void OneSixUpdate::jarlibStart()
 
 void OneSixUpdate::jarlibFinished()
 {
-	assetIndexStart();
+	OneSixInstance *inst = (OneSixInstance *)m_inst;
+	std::shared_ptr<InstanceVersion> version = inst->getFullVersion();
+
+	// create stripped jar, if needed
+	if (version->hasJarMods())
+	{
+		// FIXME: good candidate for moving elsewhere (jar location resolving/version caching).
+		QString version_id = version->id;
+		QString localPath = version_id + "/" + version_id + ".jar";
+		QString strippedPath = version_id + "/" + version_id + "-stripped.jar";
+		auto metacache = MMC->metacache();
+		auto entry = metacache->resolveEntry("versions", localPath);
+		auto entryStripped = metacache->resolveEntry("versions", strippedPath);
+
+		QString fullJarPath = entry->getFullPath();
+		QString fullStrippedJarPath = entryStripped->getFullPath();
+		QFileInfo finfo(fullStrippedJarPath);
+		if (entry->md5sum != jarHashOnEntry || !finfo.exists())
+		{
+			stripJar(fullJarPath, fullStrippedJarPath);
+		}
+	}
+	if (version->traits.contains("legacyFML"))
+	{
+		fmllibsStart();
+	}
+	else
+	{
+		assetIndexStart();
+	}
 }
 
 void OneSixUpdate::jarlibFailed()
 {
 	QStringList failed = jarlibDownloadJob->getFailedFiles();
 	QString failed_all = failed.join("\n");
-	emitFailed(tr("Failed to download the following files:\n%1\n\nPlease try again.").arg(failed_all));
+	emitFailed(
+		tr("Failed to download the following files:\n%1\n\nPlease try again.").arg(failed_all));
+}
+
+void OneSixUpdate::stripJar(QString origPath, QString newPath)
+{
+	QFileInfo runnableJar(newPath);
+	if (runnableJar.exists() && !QFile::remove(runnableJar.filePath()))
+	{
+		emitFailed("Failed to delete old minecraft.jar");
+		return;
+	}
+
+	// TaskStep(); // STEP 1
+	setStatus(tr("Creating stripped jar: Opening minecraft.jar ..."));
+
+	QuaZip zipOut(runnableJar.filePath());
+	if (!zipOut.open(QuaZip::mdCreate))
+	{
+		QFile::remove(runnableJar.filePath());
+		emitFailed("Failed to open the minecraft.jar for stripping");
+		return;
+	}
+	// Modify the jar
+	setStatus(tr("Creating stripped jar: Adding files..."));
+	if (!MergeZipFiles(&zipOut, origPath))
+	{
+		zipOut.close();
+		QFile::remove(runnableJar.filePath());
+		emitFailed("Failed to add " + origPath + " to the jar.");
+		return;
+	}
+}
+
+bool OneSixUpdate::MergeZipFiles(QuaZip *into, QString from)
+{
+	setStatus(tr("Installing mods: Adding ") + from + " ...");
+
+	QuaZip modZip(from);
+	modZip.open(QuaZip::mdUnzip);
+
+	QuaZipFile fileInsideMod(&modZip);
+	QuaZipFile zipOutFile(into);
+	for (bool more = modZip.goToFirstFile(); more; more = modZip.goToNextFile())
+	{
+		QString filename = modZip.getCurrentFileName();
+		if (filename.contains("META-INF"))
+		{
+			QLOG_INFO() << "Skipping META-INF " << filename << " from " << from;
+			continue;
+		}
+		QLOG_INFO() << "Adding file " << filename << " from " << from;
+
+		if (!fileInsideMod.open(QIODevice::ReadOnly))
+		{
+			QLOG_ERROR() << "Failed to open " << filename << " from " << from;
+			return false;
+		}
+		/*
+		QuaZipFileInfo old_info;
+		fileInsideMod.getFileInfo(&old_info);
+		*/
+		QuaZipNewInfo info_out(fileInsideMod.getActualFileName());
+		/*
+		info_out.externalAttr = old_info.externalAttr;
+		*/
+		if (!zipOutFile.open(QIODevice::WriteOnly, info_out))
+		{
+			QLOG_ERROR() << "Failed to open " << filename << " in the jar";
+			fileInsideMod.close();
+			return false;
+		}
+		if (!JlCompress::copyData(fileInsideMod, zipOutFile))
+		{
+			zipOutFile.close();
+			fileInsideMod.close();
+			QLOG_ERROR() << "Failed to copy data of " << filename << " into the jar";
+			return false;
+		}
+		zipOutFile.close();
+		fileInsideMod.close();
+	}
+	return true;
+}
+
+void OneSixUpdate::fmllibsStart()
+{
+	// Get the mod list
+	OneSixInstance *inst = (OneSixInstance *)m_inst;
+	std::shared_ptr<InstanceVersion> fullversion = inst->getFullVersion();
+	bool forge_present = false;
+
+	QString version = inst->intendedVersionId();
+	auto &fmlLibsMapping = g_VersionFilterData.fmlLibsMapping;
+	if (!fmlLibsMapping.contains(version))
+	{
+		assetIndexStart();
+		return;
+	}
+
+	auto &libList = fmlLibsMapping[version];
+
+	// determine if we need some libs for FML or forge
+	setStatus(tr("Checking for FML libraries..."));
+	forge_present = (fullversion->versionPatch("net.minecraftforge") != nullptr);
+	// we don't...
+	if (!forge_present)
+	{
+		assetIndexStart();
+		return;
+	}
+
+	// now check the lib folder inside the instance for files.
+	for (auto &lib : libList)
+	{
+		QFileInfo libInfo(PathCombine(inst->libDir(), lib.filename));
+		if (libInfo.exists())
+			continue;
+		fmlLibsToProcess.append(lib);
+	}
+
+	// if everything is in place, there's nothing to do here...
+	if (fmlLibsToProcess.isEmpty())
+	{
+		assetIndexStart();
+		return;
+	}
+
+	// download missing libs to our place
+	setStatus(tr("Dowloading FML libraries..."));
+	auto dljob = new NetJob("FML libraries");
+	auto metacache = MMC->metacache();
+	for (auto &lib : fmlLibsToProcess)
+	{
+		auto entry = metacache->resolveEntry("fmllibs", lib.filename);
+		QString urlString = lib.ours ? URLConstants::FMLLIBS_OUR_BASE_URL + lib.filename
+									 : URLConstants::FMLLIBS_FORGE_BASE_URL + lib.filename;
+		dljob->addNetAction(CacheDownload::make(QUrl(urlString), entry));
+	}
+
+	connect(dljob, SIGNAL(succeeded()), SLOT(fmllibsFinished()));
+	connect(dljob, SIGNAL(failed()), SLOT(fmllibsFailed()));
+	connect(dljob, SIGNAL(progress(qint64, qint64)), SIGNAL(progress(qint64, qint64)));
+	legacyDownloadJob.reset(dljob);
+	legacyDownloadJob->start();
+}
+
+void OneSixUpdate::fmllibsFinished()
+{
+	legacyDownloadJob.reset();
+	if (!fmlLibsToProcess.isEmpty())
+	{
+		setStatus(tr("Copying FML libraries into the instance..."));
+		OneSixInstance *inst = (OneSixInstance *)m_inst;
+		auto metacache = MMC->metacache();
+		int index = 0;
+		for (auto &lib : fmlLibsToProcess)
+		{
+			progress(index, fmlLibsToProcess.size());
+			auto entry = metacache->resolveEntry("fmllibs", lib.filename);
+			auto path = PathCombine(inst->libDir(), lib.filename);
+			if (!ensureFilePathExists(path))
+			{
+				emitFailed(tr("Failed creating FML library folder inside the instance."));
+				return;
+			}
+			if (!QFile::copy(entry->getFullPath(), PathCombine(inst->libDir(), lib.filename)))
+			{
+				emitFailed(tr("Failed copying Forge/FML library: %1.").arg(lib.filename));
+				return;
+			}
+			index++;
+		}
+		progress(index, fmlLibsToProcess.size());
+	}
+	assetIndexStart();
+}
+
+void OneSixUpdate::fmllibsFailed()
+{
+	emitFailed("Game update failed: it was impossible to fetch the required FML libraries.");
+	return;
 }
diff --git a/logic/OneSixUpdate.h b/logic/OneSixUpdate.h
index eac882b5..139143db 100644
--- a/logic/OneSixUpdate.h
+++ b/logic/OneSixUpdate.h
@@ -21,6 +21,8 @@
 
 #include "logic/net/NetJob.h"
 #include "logic/tasks/Task.h"
+#include "logic/VersionFilterData.h"
+#include <quazip.h>
 
 class MinecraftVersion;
 class OneSixInstance;
@@ -34,14 +36,16 @@ public:
 
 private
 slots:
-	void versionFileStart();
-	void versionFileFinished();
-	void versionFileFailed();
+	void versionUpdateFailed(QString reason);
 
 	void jarlibStart();
 	void jarlibFinished();
 	void jarlibFailed();
 
+	void fmllibsStart();
+	void fmllibsFinished();
+	void fmllibsFailed();
+
 	void assetIndexStart();
 	void assetIndexFinished();
 	void assetIndexFailed();
@@ -49,11 +53,18 @@ slots:
 	void assetsFinished();
 	void assetsFailed();
 
+	void stripJar(QString origPath, QString newPath);
+	bool MergeZipFiles(QuaZip *into, QString from);
 private:
-	NetJobPtr specificVersionDownloadJob;
 	NetJobPtr jarlibDownloadJob;
+	NetJobPtr legacyDownloadJob;
 
-	// target version, determined during this task
+	/// target version, determined during this task
 	std::shared_ptr<MinecraftVersion> targetVersion;
+	/// the task that is spawned for version updates
+	std::shared_ptr<Task> versionUpdateTask;
+	
 	OneSixInstance *m_inst = nullptr;
+	QString jarHashOnEntry;
+	QList<FMLlib> fmlLibsToProcess;
 };
diff --git a/logic/OneSixVersionBuilder.cpp b/logic/OneSixVersionBuilder.cpp
deleted file mode 100644
index be3a7da4..00000000
--- a/logic/OneSixVersionBuilder.cpp
+++ /dev/null
@@ -1,252 +0,0 @@
-/* Copyright 2013 MultiMC Contributors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include "OneSixVersionBuilder.h"
-
-#include <QList>
-#include <QJsonObject>
-#include <QJsonArray>
-#include <QJsonDocument>
-#include <QFile>
-#include <QFileInfo>
-#include <QMessageBox>
-#include <QObject>
-#include <QDir>
-#include <QDebug>
-
-#include "VersionFinal.h"
-#include "OneSixInstance.h"
-#include "OneSixRule.h"
-#include "VersionFile.h"
-#include "MMCJson.h"
-#include "modutils.h"
-#include "logger/QsLog.h"
-
-OneSixVersionBuilder::OneSixVersionBuilder()
-{
-}
-
-void OneSixVersionBuilder::build(VersionFinal *version, OneSixInstance *instance,
-								 const bool onlyVanilla, const QStringList &external)
-{
-	OneSixVersionBuilder builder;
-	builder.m_version = version;
-	builder.m_instance = instance;
-	builder.buildInternal(onlyVanilla, external);
-}
-
-void OneSixVersionBuilder::readJsonAndApplyToVersion(VersionFinal *version,
-													 const QJsonObject &obj)
-{
-	OneSixVersionBuilder builder;
-	builder.m_version = version;
-	builder.m_instance = 0;
-	builder.readJsonAndApply(obj);
-}
-
-void OneSixVersionBuilder::buildInternal(const bool onlyVanilla, const QStringList &external)
-{
-	m_version->versionFiles.clear();
-
-	QDir root(m_instance->instanceRoot());
-	QDir patches(root.absoluteFilePath("patches/"));
-
-	// if we do external files, do just those.
-	if (!external.isEmpty())
-	{
-		int externalOrder = -1;
-		for (auto fileName : external)
-		{
-			QLOG_INFO() << "Reading" << fileName;
-			auto file =
-				parseJsonFile(QFileInfo(fileName), false, fileName.endsWith("pack.json"));
-			file->name = QFileInfo(fileName).fileName();
-			file->fileId = "org.multimc.external." + file->name;
-			file->order = (externalOrder += 1);
-			file->version = QString();
-			file->mcVersion = QString();
-			m_version->versionFiles.append(file);
-		}
-	}
-	// else, if there's custom json, we just do that.
-	else if (QFile::exists(root.absoluteFilePath("custom.json")))
-	{
-		QLOG_INFO() << "Reading custom.json";
-		auto file = parseJsonFile(QFileInfo(root.absoluteFilePath("custom.json")), false);
-		file->name = "custom.json";
-		file->filename = "custom.json";
-		file->fileId = "org.multimc.custom.json";
-		file->order = -1;
-		file->version = QString();
-		m_version->versionFiles.append(file);
-		// QObject::tr("The version descriptors of this instance are not compatible with the
-		// current version of MultiMC"));
-		// QObject::tr("Error while applying %1. Please check MultiMC-0.log for more info.")
-	}
-	// version.json -> patches/*.json -> user.json
-	else
-		do
-		{
-			// version.json
-			QLOG_INFO() << "Reading version.json";
-			auto file = parseJsonFile(QFileInfo(root.absoluteFilePath("version.json")), false);
-			file->name = "Minecraft";
-			file->fileId = "org.multimc.version.json";
-			file->order = -1;
-			file->version = m_instance->intendedVersionId();
-			file->mcVersion = m_instance->intendedVersionId();
-			m_version->versionFiles.append(file);
-			// QObject::tr("Error while applying %1. Please check MultiMC-0.log for more
-			// info.").arg(root.absoluteFilePath("version.json")));
-
-			if (onlyVanilla)
-				break;
-
-			// patches/
-			// load all, put into map for ordering, apply in the right order
-
-			QMap<int, QPair<QString, VersionFilePtr>> files;
-			for (auto info : patches.entryInfoList(QStringList() << "*.json", QDir::Files))
-			{
-				QLOG_INFO() << "Reading" << info.fileName();
-				auto file = parseJsonFile(info, true);
-				if (files.contains(file->order))
-				{
-					throw VersionBuildError(QObject::tr("%1 has the same order as %2").arg(
-						file->fileId, files[file->order].second->fileId));
-				}
-				files.insert(file->order, qMakePair(info.fileName(), file));
-			}
-			for (auto order : files.keys())
-			{
-				auto &filePair = files[order];
-				m_version->versionFiles.append(filePair.second);
-			}
-		} while (0);
-
-	// some final touches
-	m_version->finalize();
-}
-
-
-
-void OneSixVersionBuilder::readJsonAndApply(const QJsonObject &obj)
-{
-	m_version->clear();
-
-	auto file = VersionFile::fromJson(QJsonDocument(obj), QString(), false);
-	// QObject::tr("Error while reading. Please check MultiMC-0.log for more info."));
-
-	file->applyTo(m_version);
-	m_version->versionFiles.append(file);
-	// QObject::tr("Error while applying. Please check MultiMC-0.log for more info."));
-	// QObject::tr("The version descriptors of this instance are not compatible with the current
-	// version of MultiMC"));
-}
-
-VersionFilePtr OneSixVersionBuilder::parseJsonFile(const QFileInfo &fileInfo,
-												   const bool requireOrder, bool isFTB)
-{
-	QFile file(fileInfo.absoluteFilePath());
-	if (!file.open(QFile::ReadOnly))
-	{
-		throw JSONValidationError(QObject::tr("Unable to open the version file %1: %2.")
-									  .arg(fileInfo.fileName(), file.errorString()));
-	}
-	QJsonParseError error;
-	QJsonDocument doc = QJsonDocument::fromJson(file.readAll(), &error);
-	if (error.error != QJsonParseError::NoError)
-	{
-		throw JSONValidationError(QObject::tr("Unable to process the version file %1: %2 at %3.")
-									  .arg(fileInfo.fileName(), error.errorString())
-									  .arg(error.offset));
-	}
-	return VersionFile::fromJson(doc, file.fileName(), requireOrder, isFTB);
-	// QObject::tr("Error while reading %1. Please check MultiMC-0.log for more
-	// info.").arg(file.fileName());
-}
-
-QMap<QString, int> OneSixVersionBuilder::readOverrideOrders(OneSixInstance *instance)
-{
-	QMap<QString, int> out;
-
-	// make sure the order file exists
-	if (!QDir(instance->instanceRoot()).exists("order.json"))
-		return out;
-
-	// and it can be opened
-	QFile orderFile(instance->instanceRoot() + "/order.json");
-	if (!orderFile.open(QFile::ReadOnly))
-	{
-		QLOG_ERROR() << "Couldn't open" << orderFile.fileName()
-					 << " for reading:" << orderFile.errorString();
-		QLOG_WARN() << "Ignoring overriden order";
-		return out;
-	}
-
-	// and it's valid JSON
-	QJsonParseError error;
-	QJsonDocument doc = QJsonDocument::fromJson(orderFile.readAll(), &error);
-	if (error.error != QJsonParseError::NoError)
-	{
-		QLOG_ERROR() << "Couldn't parse" << orderFile.fileName() << ":" << error.errorString();
-		QLOG_WARN() << "Ignoring overriden order";
-		return out;
-	}
-
-	// and then read it and process it if all above is true.
-	try
-	{
-		auto obj = MMCJson::ensureObject(doc);
-		for (auto it = obj.begin(); it != obj.end(); ++it)
-		{
-			if (it.key().startsWith("org.multimc."))
-			{
-				continue;
-			}
-			out.insert(it.key(), MMCJson::ensureInteger(it.value()));
-		}
-	}
-	catch (JSONValidationError &err)
-	{
-		QLOG_ERROR() << "Couldn't parse" << orderFile.fileName() << ": bad file format";
-		QLOG_WARN() << "Ignoring overriden order";
-		return out;
-	}
-	return out;
-}
-
-bool OneSixVersionBuilder::writeOverrideOrders(const QMap<QString, int> &order,
-											   OneSixInstance *instance)
-{
-	QJsonObject obj;
-	for (auto it = order.cbegin(); it != order.cend(); ++it)
-	{
-		if (it.key().startsWith("org.multimc."))
-		{
-			continue;
-		}
-		obj.insert(it.key(), it.value());
-	}
-	QFile orderFile(instance->instanceRoot() + "/order.json");
-	if (!orderFile.open(QFile::WriteOnly))
-	{
-		QLOG_ERROR() << "Couldn't open" << orderFile.fileName()
-					 << "for writing:" << orderFile.errorString();
-		return false;
-	}
-	orderFile.write(QJsonDocument(obj).toJson(QJsonDocument::Indented));
-	return true;
-}
diff --git a/logic/OneSixVersionBuilder.h b/logic/OneSixVersionBuilder.h
deleted file mode 100644
index 7a799e5b..00000000
--- a/logic/OneSixVersionBuilder.h
+++ /dev/null
@@ -1,47 +0,0 @@
-/* Copyright 2013 MultiMC Contributors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#pragma once
-
-#include <QString>
-#include <QMap>
-#include "VersionFile.h"
-
-class VersionFinal;
-class OneSixInstance;
-class QJsonObject;
-class QFileInfo;
-
-class OneSixVersionBuilder
-{
-	OneSixVersionBuilder();
-public:
-	static void build(VersionFinal *version, OneSixInstance *instance, const bool onlyVanilla,
-					  const QStringList &external);
-	static void readJsonAndApplyToVersion(VersionFinal *version, const QJsonObject &obj);
-
-	static QMap<QString, int> readOverrideOrders(OneSixInstance *instance);
-	static bool writeOverrideOrders(const QMap<QString, int> &order, OneSixInstance *instance);
-
-private:
-	VersionFinal *m_version;
-	OneSixInstance *m_instance;
-
-	void buildInternal(const bool onlyVanilla, const QStringList &external);
-	void readJsonAndApply(const QJsonObject &obj);
-
-	VersionFilePtr parseJsonFile(const QFileInfo &fileInfo, const bool requireOrder,
-							  bool isFTB = false);
-};
diff --git a/logic/URNResolver.cpp b/logic/URNResolver.cpp
new file mode 100644
index 00000000..b6bdcf41
--- /dev/null
+++ b/logic/URNResolver.cpp
@@ -0,0 +1,98 @@
+#include "URNResolver.h"
+#include <logger/QsLog.h>
+#include "MultiMC.h"
+#include "logic/forge/ForgeVersionList.h"
+#include "logic/forge/ForgeVersion.h"
+
+QString unescapeNSS(QString RawNSS)
+{
+	QString NSS;
+	NSS.reserve(RawNSS.size());
+	enum
+	{
+		Normal,
+		FirstHex,
+		SecondHex
+	} ParseState = Normal;
+
+	QByteArray translator("  ");
+
+	for (auto ch : RawNSS)
+	{
+		if(ParseState == Normal)
+		{
+			if(ch == '%')
+			{
+				ParseState = FirstHex;
+				continue;
+			}
+			else
+			{
+				NSS.append(ch);
+			}
+		}
+		if(ParseState == FirstHex)
+		{
+			translator[0] = ch.toLower().unicode();
+			ParseState = SecondHex;
+		}
+		else if(ParseState == SecondHex)
+		{
+			translator[1] = ch.toLower().unicode();
+			auto result = QByteArray::fromHex(translator);
+			if (result[0] == '\0')
+				return NSS;
+			NSS.append(result);
+			ParseState = Normal;
+		}
+	}
+	return NSS;
+}
+
+bool URNResolver::parse(const QString &URN, QString &NID, QString &NSS)
+{
+	QRegExp URNPattern(
+		"^urn:([a-z0-9][a-z0-9-]{0,31}):(([a-z0-9()+,\\-.:=@;$_!*']|%[0-9a-f]{2})+).*",
+		Qt::CaseInsensitive);
+	if (URNPattern.indexIn(URN) == -1)
+		return false;
+	auto captures = URNPattern.capturedTexts();
+	QString RawNID = captures[1];
+	QString RawNSS = captures[2];
+
+	NID = RawNID.toLower();
+	NSS = unescapeNSS(RawNSS);
+	return true;
+}
+
+URNResolver::URNResolver()
+{
+}
+
+QVariant URNResolver::resolve(QString URN)
+{
+	QString NID, NSS;
+	parse(URN, NID, NSS);
+
+	if(NID != "x-mmc")
+		return QVariant();
+	auto parts = NSS.split(":");
+	if(parts.size() < 1)
+		return QVariant();
+	unsigned int version = parts[0].toUInt();
+	switch(version)
+	{
+		case 1:
+			return resolveV1(parts.mid(1));
+		default:
+			return QVariant();
+	}
+}
+
+/**
+ * TODO: implement.
+ */
+QVariant URNResolver::resolveV1(QStringList parts)
+{
+	return QVariant();
+}
diff --git a/logic/URNResolver.h b/logic/URNResolver.h
new file mode 100644
index 00000000..dfc7f5eb
--- /dev/null
+++ b/logic/URNResolver.h
@@ -0,0 +1,18 @@
+#pragma once
+#include <QString>
+#include <QMap>
+#include <memory>
+#include <QVariant>
+
+class URNResolver;
+typedef std::shared_ptr<URNResolver> URNResolverPtr;
+
+class URNResolver
+{
+public:
+	URNResolver();
+	QVariant resolve (QString URN);
+	static bool parse (const QString &URN, QString &NID, QString &NSS);
+private:
+	QVariant resolveV1 (QStringList parts);
+};
diff --git a/logic/VersionFile.h b/logic/VersionFile.h
deleted file mode 100644
index 169a2066..00000000
--- a/logic/VersionFile.h
+++ /dev/null
@@ -1,127 +0,0 @@
-#pragma once
-
-#include <QString>
-#include <QStringList>
-#include <memory>
-#include "logic/OpSys.h"
-#include "logic/OneSixRule.h"
-#include "MMCError.h"
-
-class VersionFinal;
-
-class VersionBuildError : public MMCError
-{
-public:
-	VersionBuildError(QString cause) : MMCError(cause) {};
-	virtual ~VersionBuildError() noexcept {}
-};
-
-/**
- * the base version file was meant for a newer version of the vanilla launcher than we support
- */
-class LauncherVersionError : public VersionBuildError
-{
-public:
-	LauncherVersionError(int actual, int supported)
-		: VersionBuildError(QObject::tr(
-			  "The base version file of this instance was meant for a newer (%1) "
-			  "version of the vanilla launcher than this version of MultiMC supports (%2).")
-								.arg(actual)
-								.arg(supported)) {};
-	virtual ~LauncherVersionError() noexcept {}
-};
-
-/**
- * some patch was intended for a different version of minecraft
- */
-class MinecraftVersionMismatch : public VersionBuildError
-{
-public:
-	MinecraftVersionMismatch(QString fileId, QString mcVersion, QString parentMcVersion)
-		: VersionBuildError(QObject::tr("The patch %1 is for a different version of Minecraft "
-										"(%2) than that of the instance (%3).")
-								.arg(fileId)
-								.arg(mcVersion)
-								.arg(parentMcVersion)) {};
-	virtual ~MinecraftVersionMismatch() noexcept {}
-};
-
-struct RawLibrary;
-typedef std::shared_ptr<RawLibrary> RawLibraryPtr;
-struct RawLibrary
-{
-	QString name;
-	QString url;
-	QString hint;
-	QString absoluteUrl;
-	bool applyExcludes = false;
-	QStringList excludes;
-	bool applyNatives = false;
-	QList<QPair<OpSys, QString>> natives;
-	bool applyRules = false;
-	QList<std::shared_ptr<Rule>> rules;
-
-	// user for '+' libraries
-	enum InsertType
-	{
-		Apply,
-		Append,
-		Prepend,
-		Replace
-	};
-	InsertType insertType = Append;
-	QString insertData;
-	enum DependType
-	{
-		Soft,
-		Hard
-	};
-	DependType dependType = Soft;
-
-	static RawLibraryPtr fromJson(const QJsonObject &libObj, const QString &filename);
-};
-
-struct VersionFile;
-typedef std::shared_ptr<VersionFile> VersionFilePtr;
-struct VersionFile
-{
-public: /* methods */
-	static VersionFilePtr fromJson(const QJsonDocument &doc, const QString &filename,
-								   const bool requireOrder, const bool isFTB = false);
-
-	static OneSixLibraryPtr createLibrary(RawLibraryPtr lib);
-	int findLibrary(QList<OneSixLibraryPtr> haystack, const QString &needle);
-	void applyTo(VersionFinal *version);
-
-public: /* data */
-	int order = 0;
-	QString name;
-	QString fileId;
-	QString version;
-	// TODO use the mcVersion to determine if a version file should be removed on update
-	QString mcVersion;
-	QString filename;
-	// TODO requirements
-	// QMap<QString, QString> requirements;
-	QString id;
-	QString mainClass;
-	QString overwriteMinecraftArguments;
-	QString addMinecraftArguments;
-	QString removeMinecraftArguments;
-	QString processArguments;
-	QString type;
-	QString releaseTime;
-	QString time;
-	QString assets;
-	int minimumLauncherVersion = -1;
-
-	bool shouldOverwriteTweakers = false;
-	QStringList overwriteTweakers;
-	QStringList addTweakers;
-	QStringList removeTweakers;
-
-	bool shouldOverwriteLibs = false;
-	QList<RawLibraryPtr> overwriteLibs;
-	QList<RawLibraryPtr> addLibs;
-	QList<QString> removeLibs;
-};
diff --git a/logic/VersionFilterData.cpp b/logic/VersionFilterData.cpp
new file mode 100644
index 00000000..8b521266
--- /dev/null
+++ b/logic/VersionFilterData.cpp
@@ -0,0 +1,68 @@
+#include "VersionFilterData.h"
+#include "minecraft/ParseUtils.h"
+
+extern VersionFilterData g_VersionFilterData = VersionFilterData();
+
+VersionFilterData::VersionFilterData()
+{
+	// 1.3.*
+	auto libs13 =
+		QList<FMLlib>{{"argo-2.25.jar", "bb672829fde76cb163004752b86b0484bd0a7f4b", false},
+					  {"guava-12.0.1.jar", "b8e78b9af7bf45900e14c6f958486b6ca682195f", false},
+					  {"asm-all-4.0.jar", "98308890597acb64047f7e896638e0d98753ae82", false}};
+
+	fmlLibsMapping["1.3.2"] = libs13;
+
+	// 1.4.*
+	auto libs14 = QList<FMLlib>{
+		{"argo-2.25.jar", "bb672829fde76cb163004752b86b0484bd0a7f4b", false},
+		{"guava-12.0.1.jar", "b8e78b9af7bf45900e14c6f958486b6ca682195f", false},
+		{"asm-all-4.0.jar", "98308890597acb64047f7e896638e0d98753ae82", false},
+		{"bcprov-jdk15on-147.jar", "b6f5d9926b0afbde9f4dbe3db88c5247be7794bb", false}};
+
+	fmlLibsMapping["1.4"] = libs14;
+	fmlLibsMapping["1.4.1"] = libs14;
+	fmlLibsMapping["1.4.2"] = libs14;
+	fmlLibsMapping["1.4.3"] = libs14;
+	fmlLibsMapping["1.4.4"] = libs14;
+	fmlLibsMapping["1.4.5"] = libs14;
+	fmlLibsMapping["1.4.6"] = libs14;
+	fmlLibsMapping["1.4.7"] = libs14;
+
+	// 1.5
+	fmlLibsMapping["1.5"] = QList<FMLlib>{
+		{"argo-small-3.2.jar", "58912ea2858d168c50781f956fa5b59f0f7c6b51", false},
+		{"guava-14.0-rc3.jar", "931ae21fa8014c3ce686aaa621eae565fefb1a6a", false},
+		{"asm-all-4.1.jar", "054986e962b88d8660ae4566475658469595ef58", false},
+		{"bcprov-jdk15on-148.jar", "960dea7c9181ba0b17e8bab0c06a43f0a5f04e65", true},
+		{"deobfuscation_data_1.5.zip", "5f7c142d53776f16304c0bbe10542014abad6af8", false},
+		{"scala-library.jar", "458d046151ad179c85429ed7420ffb1eaf6ddf85", true}};
+
+	// 1.5.1
+	fmlLibsMapping["1.5.1"] = QList<FMLlib>{
+		{"argo-small-3.2.jar", "58912ea2858d168c50781f956fa5b59f0f7c6b51", false},
+		{"guava-14.0-rc3.jar", "931ae21fa8014c3ce686aaa621eae565fefb1a6a", false},
+		{"asm-all-4.1.jar", "054986e962b88d8660ae4566475658469595ef58", false},
+		{"bcprov-jdk15on-148.jar", "960dea7c9181ba0b17e8bab0c06a43f0a5f04e65", true},
+		{"deobfuscation_data_1.5.1.zip", "22e221a0d89516c1f721d6cab056a7e37471d0a6", false},
+		{"scala-library.jar", "458d046151ad179c85429ed7420ffb1eaf6ddf85", true}};
+
+	// 1.5.2
+	fmlLibsMapping["1.5.2"] = QList<FMLlib>{
+		{"argo-small-3.2.jar", "58912ea2858d168c50781f956fa5b59f0f7c6b51", false},
+		{"guava-14.0-rc3.jar", "931ae21fa8014c3ce686aaa621eae565fefb1a6a", false},
+		{"asm-all-4.1.jar", "054986e962b88d8660ae4566475658469595ef58", false},
+		{"bcprov-jdk15on-148.jar", "960dea7c9181ba0b17e8bab0c06a43f0a5f04e65", true},
+		{"deobfuscation_data_1.5.2.zip", "446e55cd986582c70fcf12cb27bc00114c5adfd9", false},
+		{"scala-library.jar", "458d046151ad179c85429ed7420ffb1eaf6ddf85", true}};
+
+	// don't use installers for those.
+	forgeInstallerBlacklist = QSet<QString>({"1.5.2"});
+	// these won't show up in version lists because they are extremely bad and dangerous
+	legacyBlacklist = QSet<QString>({"rd-160052"});
+	/*
+	 * nothing older than this will be accepted from Mojang servers
+	 * (these versions need to be tested by us first)
+	 */
+	legacyCutoffDate = timeFromS3Time("2013-06-25T15:08:56+02:00");
+}
diff --git a/logic/VersionFilterData.h b/logic/VersionFilterData.h
new file mode 100644
index 00000000..e010adc7
--- /dev/null
+++ b/logic/VersionFilterData.h
@@ -0,0 +1,26 @@
+#pragma once
+#include <QMap>
+#include <QString>
+#include <QSet>
+#include <QDateTime>
+
+struct FMLlib
+{
+	QString filename;
+	QString checksum;
+	bool ours;
+};
+
+struct VersionFilterData
+{
+	VersionFilterData();
+	// mapping between minecraft versions and FML libraries required
+	QMap<QString, QList<FMLlib>> fmlLibsMapping;
+	// set of minecraft versions for which using forge installers is blacklisted
+	QSet<QString> forgeInstallerBlacklist;
+	// set of 'legacy' versions that will not show up in the version lists.
+	QSet<QString> legacyBlacklist;
+	// no new versions below this date will be accepted from Mojang servers
+	QDateTime legacyCutoffDate;
+};
+extern VersionFilterData g_VersionFilterData;
diff --git a/logic/VersionFinal.cpp b/logic/VersionFinal.cpp
deleted file mode 100644
index dedf2ce5..00000000
--- a/logic/VersionFinal.cpp
+++ /dev/null
@@ -1,377 +0,0 @@
-/* Copyright 2013 MultiMC Contributors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include "VersionFinal.h"
-
-#include <QDebug>
-#include <QFile>
-#include <QDir>
-
-#include "OneSixVersionBuilder.h"
-#include "OneSixInstance.h"
-
-template <typename A, typename B> QMap<A, B> invert(const QMap<B, A> &in)
-{
-	QMap<A, B> out;
-	for (auto it = in.begin(); it != in.end(); ++it)
-	{
-		out.insert(it.value(), it.key());
-	}
-	return out;
-}
-
-VersionFinal::VersionFinal(OneSixInstance *instance, QObject *parent)
-	: QAbstractListModel(parent), m_instance(instance)
-{
-	clear();
-}
-
-void VersionFinal::reload(const bool onlyVanilla, const QStringList &external)
-{
-	//FIXME: source of epic failure.
-	beginResetModel();
-	OneSixVersionBuilder::build(this, m_instance, onlyVanilla, external);
-	reapply(true);
-	endResetModel();
-}
-
-void VersionFinal::clear()
-{
-	id.clear();
-	time.clear();
-	releaseTime.clear();
-	type.clear();
-	assets.clear();
-	processArguments.clear();
-	minecraftArguments.clear();
-	minimumLauncherVersion = 0xDEADBEAF;
-	mainClass.clear();
-	libraries.clear();
-	tweakers.clear();
-}
-
-bool VersionFinal::canRemove(const int index) const
-{
-	if (index < versionFiles.size())
-	{
-		return versionFiles.at(index)->fileId != "org.multimc.version.json";
-	}
-	return false;
-}
-
-bool VersionFinal::remove(const int index)
-{
-	if (canRemove(index) && QFile::remove(versionFiles.at(index)->filename))
-	{
-		beginResetModel();
-		versionFiles.removeAt(index);
-		reapply(true);
-		endResetModel();
-		return true;
-	}
-	return false;
-}
-
-bool VersionFinal::remove(const QString id)
-{
-	int i = 0;
-	for (auto file : versionFiles)
-	{
-		if (file->fileId == id)
-		{
-			return remove(i);
-		}
-		i++;
-	}
-	return false;
-}
-
-QString VersionFinal::versionFileId(const int index) const
-{
-	if (index < 0 || index >= versionFiles.size())
-	{
-		return QString();
-	}
-	return versionFiles.at(index)->fileId;
-}
-
-VersionFilePtr VersionFinal::versionFile(const QString &id)
-{
-	for (auto file : versionFiles)
-	{
-		if (file->fileId == id)
-		{
-			return file;
-		}
-	}
-	return 0;
-}
-
-bool VersionFinal::hasFtbPack()
-{
-	return versionFile("org.multimc.ftb.pack.json") != nullptr;
-}
-
-bool VersionFinal::removeFtbPack()
-{
-	return remove("org.multimc.ftb.pack.json");
-}
-
-QList<std::shared_ptr<OneSixLibrary> > VersionFinal::getActiveNormalLibs()
-{
-	QList<std::shared_ptr<OneSixLibrary> > output;
-	for (auto lib : libraries)
-	{
-		if (lib->isActive() && !lib->isNative())
-		{
-			output.append(lib);
-		}
-	}
-	return output;
-}
-QList<std::shared_ptr<OneSixLibrary> > VersionFinal::getActiveNativeLibs()
-{
-	QList<std::shared_ptr<OneSixLibrary> > output;
-	for (auto lib : libraries)
-	{
-		if (lib->isActive() && lib->isNative())
-		{
-			output.append(lib);
-		}
-	}
-	return output;
-}
-
-std::shared_ptr<VersionFinal> VersionFinal::fromJson(const QJsonObject &obj)
-{
-	std::shared_ptr<VersionFinal> version(new VersionFinal(0));
-	try
-	{
-		OneSixVersionBuilder::readJsonAndApplyToVersion(version.get(), obj);
-	}
-	catch(MMCError & err)
-	{
-		return 0;
-	}
-	return version;
-}
-
-QVariant VersionFinal::data(const QModelIndex &index, int role) const
-{
-	if (!index.isValid())
-		return QVariant();
-
-	int row = index.row();
-	int column = index.column();
-
-	if (row < 0 || row >= versionFiles.size())
-		return QVariant();
-
-	if (role == Qt::DisplayRole)
-	{
-		switch (column)
-		{
-		case 0:
-			return versionFiles.at(row)->name;
-		case 1:
-			return versionFiles.at(row)->version;
-		default:
-			return QVariant();
-		}
-	}
-	return QVariant();
-}
-QVariant VersionFinal::headerData(int section, Qt::Orientation orientation, int role) const
-{
-	if (orientation == Qt::Horizontal)
-	{
-		if (role == Qt::DisplayRole)
-		{
-			switch (section)
-			{
-			case 0:
-				return tr("Name");
-			case 1:
-				return tr("Version");
-			default:
-				return QVariant();
-			}
-		}
-	}
-	return QVariant();
-}
-Qt::ItemFlags VersionFinal::flags(const QModelIndex &index) const
-{
-	if (!index.isValid())
-		return Qt::NoItemFlags;
-	return Qt::ItemIsSelectable | Qt::ItemIsEnabled;
-}
-
-int VersionFinal::rowCount(const QModelIndex &parent) const
-{
-	return versionFiles.size();
-}
-
-int VersionFinal::columnCount(const QModelIndex &parent) const
-{
-	return 2;
-}
-
-bool VersionFinal::isCustom()
-{
-	return QDir(m_instance->instanceRoot()).exists("custom.json");
-}
-bool VersionFinal::revertToBase()
-{
-	return QDir(m_instance->instanceRoot()).remove("custom.json");
-}
-
-QMap<QString, int> VersionFinal::getExistingOrder() const
-{
-
-	QMap<QString, int> order;
-	// default
-	{
-		for (auto file : versionFiles)
-		{
-			order.insert(file->fileId, file->order);
-		}
-	}
-	// overriden
-	{
-		QMap<QString, int> overridenOrder = OneSixVersionBuilder::readOverrideOrders(m_instance);
-		for (auto id : order.keys())
-		{
-			if (overridenOrder.contains(id))
-			{
-				order[id] = overridenOrder[id];
-			}
-		}
-	}
-	return order;
-}
-
-void VersionFinal::move(const int index, const MoveDirection direction)
-{
-	int theirIndex;
-	if (direction == MoveUp)
-	{
-		theirIndex = index - 1;
-	}
-	else
-	{
-		theirIndex = index + 1;
-	}
-	if (theirIndex < 0 || theirIndex >= versionFiles.size())
-	{
-		return;
-	}
-	const QString ourId = versionFileId(index);
-	const QString theirId = versionFileId(theirIndex);
-	if (ourId.isNull() || ourId.startsWith("org.multimc.") ||
-			theirId.isNull() || theirId.startsWith("org.multimc."))
-	{
-		return;
-	}
-
-	VersionFilePtr we = versionFiles[index];
-	VersionFilePtr them = versionFiles[theirIndex];
-	if (!we || !them)
-	{
-		return;
-	}
-	beginMoveRows(QModelIndex(), index, index, QModelIndex(), theirIndex);
-	versionFiles.replace(theirIndex, we);
-	versionFiles.replace(index, them);
-	endMoveRows();
-
-	auto order = getExistingOrder();
-	order[ourId] = theirIndex;
-	order[theirId] = index;
-
-	if (!OneSixVersionBuilder::writeOverrideOrders(order, m_instance))
-	{
-		throw MMCError(tr("Couldn't save the new order"));
-	}
-	else
-	{
-		reapply();
-	}
-}
-void VersionFinal::resetOrder()
-{
-	QDir(m_instance->instanceRoot()).remove("order.json");
-	reapply();
-}
-
-void VersionFinal::reapply(const bool alreadyReseting)
-{
-	if (!alreadyReseting)
-	{
-		beginResetModel();
-	}
-
-	clear();
-
-	auto existingOrders = getExistingOrder();
-	QList<int> orders = existingOrders.values();
-	std::sort(orders.begin(), orders.end());
-	QList<VersionFilePtr> newVersionFiles;
-	for (auto order : orders)
-	{
-		auto file = versionFile(existingOrders.key(order));
-		newVersionFiles.append(file);
-		file->applyTo(this);
-	}
-	versionFiles.swap(newVersionFiles);
-	finalize();
-	if (!alreadyReseting)
-	{
-		endResetModel();
-	}
-}
-
-void VersionFinal::finalize()
-{
-	// HACK: deny april fools. my head hurts enough already.
-	QDate now = QDate::currentDate();
-	bool isAprilFools = now.month() == 4 && now.day() == 1;
-	if (assets.endsWith("_af") && !isAprilFools)
-	{
-		assets = assets.left(assets.length() - 3);
-	}
-	if (assets.isEmpty())
-	{
-		assets = "legacy";
-	}
-	if (minecraftArguments.isEmpty())
-	{
-		QString toCompare = processArguments.toLower();
-		if (toCompare == "legacy")
-		{
-			minecraftArguments = " ${auth_player_name} ${auth_session}";
-		}
-		else if (toCompare == "username_session")
-		{
-			minecraftArguments = "--username ${auth_player_name} --session ${auth_session}";
-		}
-		else if (toCompare == "username_session_version")
-		{
-			minecraftArguments = "--username ${auth_player_name} "
-								 "--session ${auth_session} "
-								 "--version ${profile_name}";
-		}
-	}
-}
diff --git a/logic/ForgeInstaller.cpp b/logic/forge/ForgeInstaller.cpp
index 94b3f319..7f952408 100644
--- a/logic/ForgeInstaller.cpp
+++ b/logic/forge/ForgeInstaller.cpp
@@ -14,9 +14,15 @@
  */
 
 #include "ForgeInstaller.h"
-#include "VersionFinal.h"
-#include "OneSixLibrary.h"
-#include "net/HttpMetaCache.h"
+#include "logic/minecraft/InstanceVersion.h"
+#include "logic/minecraft/OneSixLibrary.h"
+#include "logic/net/HttpMetaCache.h"
+#include "logic/tasks/Task.h"
+#include "logic/OneSixInstance.h"
+#include "logic/forge/ForgeVersionList.h"
+#include "logic/VersionFilterData.h"
+#include "gui/dialogs/ProgressDialog.h"
+
 #include <quazip.h>
 #include <quazipfile.h>
 #include <pathutils.h>
@@ -24,23 +30,17 @@
 #include <QRegularExpression>
 #include <QRegularExpressionMatch>
 #include "MultiMC.h"
-#include "tasks/Task.h"
-#include "OneSixInstance.h"
-#include "lists/ForgeVersionList.h"
-#include "gui/dialogs/ProgressDialog.h"
-
 #include <QJsonDocument>
 #include <QJsonArray>
 #include <QSaveFile>
 #include <QCryptographicHash>
 
-ForgeInstaller::ForgeInstaller()
-	: BaseInstaller()
+ForgeInstaller::ForgeInstaller() : BaseInstaller()
 {
 }
 void ForgeInstaller::prepare(const QString &filename, const QString &universalUrl)
 {
-	std::shared_ptr<VersionFinal> newVersion;
+	std::shared_ptr<InstanceVersion> newVersion;
 	m_universal_url = universalUrl;
 
 	QuaZip zip(filename);
@@ -73,7 +73,7 @@ void ForgeInstaller::prepare(const QString &filename, const QString &universalUr
 
 	// read the forge version info
 	{
-		newVersion = VersionFinal::fromJson(versionInfoVal.toObject());
+		newVersion = InstanceVersion::fromJson(versionInfoVal.toObject());
 		if (!newVersion)
 			return;
 	}
@@ -115,8 +115,8 @@ void ForgeInstaller::prepare(const QString &filename, const QString &universalUr
 	}
 	file.close();
 
-	m_forge_version = newVersion;
-	realVersionId = m_forge_version->id = installObj.value("minecraft").toString();
+	m_forge_json = newVersion;
+	realVersionId = m_forge_json->id = installObj.value("minecraft").toString();
 }
 bool ForgeInstaller::add(OneSixInstance *to)
 {
@@ -128,7 +128,7 @@ bool ForgeInstaller::add(OneSixInstance *to)
 	QJsonObject obj;
 	obj.insert("order", 5);
 
-	if (!m_forge_version)
+	if (!m_forge_json)
 		return false;
 	int sliding_insert_window = 0;
 	{
@@ -136,7 +136,7 @@ bool ForgeInstaller::add(OneSixInstance *to)
 
 		// for each library in the version we are adding (except for the blacklisted)
 		QSet<QString> blacklist{"lwjgl", "lwjgl_util", "lwjgl-platform"};
-		for (auto lib : m_forge_version->libraries)
+		for (auto lib : m_forge_json->libraries)
 		{
 			QString libName = lib->name();
 			// WARNING: This could actually break.
@@ -157,7 +157,7 @@ bool ForgeInstaller::add(OneSixInstance *to)
 			bool found = false;
 			bool equals = false;
 			// find an entry that matches this one
-			for (auto tolib : to->getVanillaVersion()->libraries)
+			for (auto tolib : to->getFullVersion()->vanillaLibraries)
 			{
 				if (tolib->name() != libName)
 					continue;
@@ -187,8 +187,8 @@ bool ForgeInstaller::add(OneSixInstance *to)
 			librariesPlus.prepend(libObj);
 		}
 		obj.insert("+libraries", librariesPlus);
-		obj.insert("mainClass", m_forge_version->mainClass);
-		QString args = m_forge_version->minecraftArguments;
+		obj.insert("mainClass", m_forge_json->mainClass);
+		QString args = m_forge_json->minecraftArguments;
 		QStringList tweakers;
 		{
 			QRegularExpression expression("--tweakClass ([a-zA-Z0-9\\.]*)");
@@ -200,7 +200,7 @@ bool ForgeInstaller::add(OneSixInstance *to)
 				match = expression.match(args);
 			}
 		}
-		if (!args.isEmpty() && args != to->getVanillaVersion()->minecraftArguments)
+		if (!args.isEmpty() && args != to->getFullVersion()->vanillaMinecraftArguments)
 		{
 			obj.insert("minecraftArguments", args);
 		}
@@ -208,10 +208,10 @@ bool ForgeInstaller::add(OneSixInstance *to)
 		{
 			obj.insert("+tweakers", QJsonArray::fromStringList(tweakers));
 		}
-		if (!m_forge_version->processArguments.isEmpty() &&
-			m_forge_version->processArguments != to->getVanillaVersion()->processArguments)
+		if (!m_forge_json->processArguments.isEmpty() &&
+			m_forge_json->processArguments != to->getFullVersion()->vanillaProcessArguments)
 		{
-			obj.insert("processArguments", m_forge_version->processArguments);
+			obj.insert("processArguments", m_forge_json->processArguments);
 		}
 	}
 
@@ -233,11 +233,65 @@ bool ForgeInstaller::add(OneSixInstance *to)
 	return true;
 }
 
+bool ForgeInstaller::addLegacy(OneSixInstance *to)
+{
+	if (!BaseInstaller::add(to))
+	{
+		return false;
+	}
+	auto entry = MMC->metacache()->resolveEntry("minecraftforge", m_forge_version->filename());
+	finalPath = PathCombine(to->jarModsDir(), m_forge_version->filename());
+	if (!ensureFilePathExists(finalPath))
+	{
+		return false;
+	}
+	if (!QFile::copy(entry->getFullPath(),finalPath))
+	{
+		return false;
+	}
+	QJsonObject obj;
+	obj.insert("order", 5);
+	{
+		QJsonArray jarmodsPlus;
+		{
+			QJsonObject libObj;
+			libObj.insert("name", m_forge_version->universal_filename);
+			jarmodsPlus.append(libObj);
+		}
+		obj.insert("+jarMods", jarmodsPlus);
+	}
+
+	obj.insert("name", QString("Forge"));
+	obj.insert("fileId", id());
+	obj.insert("version", m_forge_version->jobbuildver);
+	obj.insert("mcVersion", to->intendedVersionId());
+	if (g_VersionFilterData.fmlLibsMapping.contains(m_forge_version->mcver))
+	{
+		QJsonArray traitsPlus;
+		traitsPlus.append(QString("legacyFML"));
+		obj.insert("+traits", traitsPlus);
+	}
+	auto fullversion = to->getFullVersion();
+	fullversion->remove("net.minecraftforge");
+	
+	QFile file(filename(to->instanceRoot()));
+	if (!file.open(QFile::WriteOnly))
+	{
+		QLOG_ERROR() << "Error opening" << file.fileName()
+					 << "for reading:" << file.errorString();
+		return false;
+	}
+	file.write(QJsonDocument(obj).toJson());
+	file.close();
+	return true;
+}
+
 class ForgeInstallTask : public Task
 {
 	Q_OBJECT
 public:
-	ForgeInstallTask(ForgeInstaller *installer, OneSixInstance *instance, BaseVersionPtr version, QObject *parent = 0)
+	ForgeInstallTask(ForgeInstaller *installer, OneSixInstance *instance,
+					 BaseVersionPtr version, QObject *parent = 0)
 		: Task(parent), m_installer(installer), m_instance(instance), m_version(version)
 	{
 	}
@@ -245,57 +299,59 @@ public:
 protected:
 	void executeTask() override
 	{
+		setStatus(tr("Installing forge..."));
+		ForgeVersionPtr forgeVersion = std::dynamic_pointer_cast<ForgeVersion>(m_version);
+		if (!forgeVersion)
 		{
-			setStatus(tr("Installing forge..."));
-			ForgeVersionPtr forgeVersion =
-				std::dynamic_pointer_cast<ForgeVersion>(m_version);
-			if (!forgeVersion)
-			{
-				emitFailed(tr("Unknown error occured"));
-				return;
-			}
-			auto entry = MMC->metacache()->resolveEntry("minecraftforge", forgeVersion->filename);
-			if (entry->stale)
+			emitFailed(tr("Unknown error occured"));
+			return;
+		}
+		prepare(forgeVersion);
+	}
+	void prepare(ForgeVersionPtr forgeVersion)
+	{
+		auto entry = MMC->metacache()->resolveEntry("minecraftforge", forgeVersion->filename());
+		auto installFunction = [this, entry, forgeVersion]()
+		{
+			if (!install(entry, forgeVersion))
 			{
-				NetJob *fjob = new NetJob("Forge download");
-				fjob->addNetAction(CacheDownload::make(forgeVersion->installer_url, entry));
-				connect(fjob, &NetJob::progress, [this](qint64 current, qint64 total){setProgress(100 * current / qMax((qint64)1, total));});
-				connect(fjob, &NetJob::status, [this](const QString &msg){setStatus(msg);});
-				connect(fjob, &NetJob::failed, [this](){emitFailed(tr("Failure to download forge"));});
-				connect(fjob, &NetJob::succeeded, [this, entry, forgeVersion]()
-				{
-					if (!install(entry, forgeVersion))
-					{
-						QLOG_ERROR() << "Failure installing forge";
-						emitFailed(tr("Failure to install forge"));
-					}
-					else
-					{
-						reload();
-					}
-				});
-				fjob->start();
+				QLOG_ERROR() << "Failure installing forge";
+				emitFailed(tr("Failure to install forge"));
 			}
 			else
 			{
-				if (!install(entry, forgeVersion))
-				{
-					QLOG_ERROR() << "Failure installing forge";
-					emitFailed(tr("Failure to install forge"));
-				}
-				else
-				{
-					reload();
-				}
+				reload();
 			}
+		};
+
+		if (entry->stale)
+		{
+			NetJob *fjob = new NetJob("Forge download");
+			fjob->addNetAction(CacheDownload::make(forgeVersion->url(), entry));
+			connect(fjob, &NetJob::progress, [this](qint64 current, qint64 total)
+			{ setProgress(100 * current / qMax((qint64)1, total)); });
+			connect(fjob, &NetJob::status, [this](const QString & msg)
+			{ setStatus(msg); });
+			connect(fjob, &NetJob::failed, [this]()
+			{ emitFailed(tr("Failure to download forge")); });
+			connect(fjob, &NetJob::succeeded, installFunction);
+			fjob->start();
+		}
+		else
+		{
+			installFunction();
 		}
 	}
-
 	bool install(const std::shared_ptr<MetaEntry> &entry, const ForgeVersionPtr &forgeVersion)
 	{
-		QString forgePath = entry->getFullPath();
-		m_installer->prepare(forgePath, forgeVersion->universal_url);
-		return m_installer->add(m_instance);
+		if (forgeVersion->usesInstaller())
+		{
+			QString forgePath = entry->getFullPath();
+			m_installer->prepare(forgePath, forgeVersion->universal_url);
+			return m_installer->add(m_instance);
+		}
+		else
+			return m_installer->addLegacy(m_instance);
 	}
 	void reload()
 	{
@@ -320,8 +376,14 @@ private:
 	BaseVersionPtr m_version;
 };
 
-ProgressProvider *ForgeInstaller::createInstallTask(OneSixInstance *instance, BaseVersionPtr version, QObject *parent)
+ProgressProvider *ForgeInstaller::createInstallTask(OneSixInstance *instance,
+													BaseVersionPtr version, QObject *parent)
 {
+	if (!version)
+	{
+		return nullptr;
+	}
+	m_forge_version = std::dynamic_pointer_cast<ForgeVersion>(version);
 	return new ForgeInstallTask(this, instance, version, parent);
 }
 
diff --git a/logic/ForgeInstaller.h b/logic/forge/ForgeInstaller.h
index 05cc994b..14aeeb51 100644
--- a/logic/ForgeInstaller.h
+++ b/logic/forge/ForgeInstaller.h
@@ -15,28 +15,34 @@
 
 #pragma once
 
-#include "BaseInstaller.h"
+#include "logic/BaseInstaller.h"
 
 #include <QString>
 #include <memory>
 
-class VersionFinal;
+class InstanceVersion;
+class ForgeInstallTask;
+class ForgeVersion;
 
 class ForgeInstaller : public BaseInstaller
 {
+	friend class ForgeInstallTask;
 public:
 	ForgeInstaller();
+	virtual ~ForgeInstaller(){};
+	virtual ProgressProvider *createInstallTask(OneSixInstance *instance, BaseVersionPtr version, QObject *parent) override;
 
+protected:
+	virtual QString id() const override { return "net.minecraftforge"; }
 	void prepare(const QString &filename, const QString &universalUrl);
 	bool add(OneSixInstance *to) override;
-
-	QString id() const override { return "net.minecraftforge"; }
-
-	ProgressProvider *createInstallTask(OneSixInstance *instance, BaseVersionPtr version, QObject *parent) override;
+	bool addLegacy(OneSixInstance *to);
 
 private:
-	// the version, read from the installer
-	std::shared_ptr<VersionFinal> m_forge_version;
+	// the parsed version json, read from the installer
+	std::shared_ptr<InstanceVersion> m_forge_json;
+	// the actual forge version
+	std::shared_ptr<ForgeVersion> m_forge_version;
 	QString internalPath;
 	QString finalPath;
 	QString realVersionId;
diff --git a/logic/net/ForgeMirror.h b/logic/forge/ForgeMirror.h
index 2518dffe..2518dffe 100644
--- a/logic/net/ForgeMirror.h
+++ b/logic/forge/ForgeMirror.h
diff --git a/logic/net/ForgeMirrors.cpp b/logic/forge/ForgeMirrors.cpp
index b224306f..b224306f 100644
--- a/logic/net/ForgeMirrors.cpp
+++ b/logic/forge/ForgeMirrors.cpp
diff --git a/logic/net/ForgeMirrors.h b/logic/forge/ForgeMirrors.h
index 6784fba1..d25762db 100644
--- a/logic/net/ForgeMirrors.h
+++ b/logic/forge/ForgeMirrors.h
@@ -15,10 +15,10 @@
 
 #pragma once
 
-#include "NetAction.h"
-#include "HttpMetaCache.h"
-#include "ForgeXzDownload.h"
-#include "NetJob.h"
+#include "logic/net/NetAction.h"
+#include "logic/net/HttpMetaCache.h"
+#include "logic/net/NetJob.h"
+#include "logic/forge/ForgeXzDownload.h"
 #include <QFile>
 #include <QTemporaryFile>
 typedef std::shared_ptr<class ForgeMirrors> ForgeMirrorsPtr;
diff --git a/logic/forge/ForgeVersion.cpp b/logic/forge/ForgeVersion.cpp
new file mode 100644
index 00000000..3131ec39
--- /dev/null
+++ b/logic/forge/ForgeVersion.cpp
@@ -0,0 +1,55 @@
+#include "ForgeVersion.h"
+#include "logic/VersionFilterData.h"
+#include <QObject>
+
+QString ForgeVersion::name()
+{
+	return "Forge " + jobbuildver;
+}
+
+QString ForgeVersion::descriptor()
+{
+	return universal_filename;
+}
+
+QString ForgeVersion::typeString() const
+{
+	if (is_recommended)
+		return QObject::tr("Recommended");
+	return QString();
+}
+
+bool ForgeVersion::operator<(BaseVersion &a)
+{
+	ForgeVersion *pa = dynamic_cast<ForgeVersion *>(&a);
+	if (!pa)
+		return true;
+	return m_buildnr < pa->m_buildnr;
+}
+
+bool ForgeVersion::operator>(BaseVersion &a)
+{
+	ForgeVersion *pa = dynamic_cast<ForgeVersion *>(&a);
+	if (!pa)
+		return false;
+	return m_buildnr > pa->m_buildnr;
+}
+
+bool ForgeVersion::usesInstaller()
+{
+	if(installer_url.isEmpty())
+		return false;
+	if(g_VersionFilterData.forgeInstallerBlacklist.contains(mcver))
+		return false;
+	return true;
+}
+
+QString ForgeVersion::filename()
+{
+	return usesInstaller() ? installer_filename : universal_filename;
+}
+
+QString ForgeVersion::url()
+{
+	return usesInstaller() ? installer_url : universal_url;
+}
diff --git a/logic/forge/ForgeVersion.h b/logic/forge/ForgeVersion.h
new file mode 100644
index 00000000..466f46bd
--- /dev/null
+++ b/logic/forge/ForgeVersion.h
@@ -0,0 +1,33 @@
+#pragma once
+#include <QString>
+#include <memory>
+#include "logic/BaseVersion.h"
+
+struct ForgeVersion;
+typedef std::shared_ptr<ForgeVersion> ForgeVersionPtr;
+
+struct ForgeVersion : public BaseVersion
+{
+	virtual QString descriptor() override;
+	virtual QString name() override;
+	virtual QString typeString() const override;
+	virtual bool operator<(BaseVersion &a) override;
+	virtual bool operator>(BaseVersion &a) override;
+
+	QString filename();
+	QString url();
+	
+	bool usesInstaller();
+
+	int m_buildnr = 0;
+	QString branch;
+	QString universal_url;
+	QString changelog_url;
+	QString installer_url;
+	QString jobbuildver;
+	QString mcver;
+	QString mcver_sane;
+	QString universal_filename;
+	QString installer_filename;
+	bool is_recommended = false;
+};
diff --git a/logic/lists/ForgeVersionList.cpp b/logic/forge/ForgeVersionList.cpp
index 4902dc64..efb30ba6 100644
--- a/logic/lists/ForgeVersionList.cpp
+++ b/logic/forge/ForgeVersionList.cpp
@@ -13,9 +13,10 @@
  * limitations under the License.
  */
 
-#include "ForgeVersionList.h"
-#include <logic/net/NetJob.h>
-#include <logic/net/URLConstants.h>
+#include "logic/forge/ForgeVersionList.h"
+#include "logic/forge/ForgeVersion.h"
+#include "logic/net/NetJob.h"
+#include "logic/net/URLConstants.h"
 #include "MultiMC.h"
 
 #include <QtNetwork>
@@ -71,7 +72,7 @@ QVariant ForgeVersionList::data(const QModelIndex &index, int role) const
 			return version->name();
 
 		case 1:
-			return version->mcver;
+			return version->mcver_sane;
 
 		case 2:
 			return version->typeString();
@@ -236,7 +237,7 @@ bool ForgeListLoadTask::parseForgeList(QList<BaseVersionPtr> &out)
 		if (!build_nr)
 			continue;
 		QJsonArray files = obj.value("files").toArray();
-		QString url, jobbuildver, mcver, buildtype, filename;
+		QString url, jobbuildver, mcver, buildtype, universal_filename;
 		QString changelog_url, installer_url;
 		QString installer_filename;
 		bool valid = false;
@@ -254,7 +255,7 @@ bool ForgeListLoadTask::parseForgeList(QList<BaseVersionPtr> &out)
 				url = file.value("url").toString();
 				jobbuildver = file.value("jobbuildver").toString();
 				int lastSlash = url.lastIndexOf('/');
-				filename = url.mid(lastSlash + 1);
+				universal_filename = url.mid(lastSlash + 1);
 				valid = true;
 			}
 			else if (buildtype == "changelog")
@@ -281,15 +282,9 @@ bool ForgeListLoadTask::parseForgeList(QList<BaseVersionPtr> &out)
 			fVersion->changelog_url = changelog_url;
 			fVersion->installer_url = installer_url;
 			fVersion->jobbuildver = jobbuildver;
-			fVersion->mcver = mcver;
-			if (installer_filename.isEmpty())
-			{
-				fVersion->filename = filename;
-			}
-			else
-			{
-				fVersion->filename = installer_filename;
-			}
+			fVersion->mcver = fVersion->mcver_sane = mcver;
+			fVersion->installer_filename = installer_filename;
+			fVersion->universal_filename = universal_filename;
 			fVersion->m_buildnr = build_nr;
 			out.append(fVersion);
 		}
@@ -341,9 +336,17 @@ bool ForgeListLoadTask::parseForgeGradleList(QList<BaseVersionPtr> &out)
 		std::shared_ptr<ForgeVersion> fVersion(new ForgeVersion());
 		fVersion->m_buildnr = number.value("build").toDouble();
 		fVersion->jobbuildver = number.value("version").toString();
+		fVersion->branch = number.value("branch").toString("");
 		fVersion->mcver = number.value("mcversion").toString();
-		fVersion->filename = "";
-		QString filename, installer_filename;
+		fVersion->universal_filename = "";
+		fVersion->installer_filename = "";
+		// HACK: here, we fix the minecraft version used by forge.
+		// HACK: this will inevitably break (later)
+		// FIXME: replace with a dictionary
+		fVersion->mcver_sane = fVersion->mcver;
+		fVersion->mcver_sane.replace("_pre", "-pre");
+
+		QString universal_filename, installer_filename;
 		QJsonArray files = number.value("files").toArray();
 		for (auto fIt = files.begin(); fIt != files.end(); ++fIt)
 		{
@@ -353,37 +356,47 @@ bool ForgeListLoadTask::parseForgeGradleList(QList<BaseVersionPtr> &out)
 			{
 				continue;
 			}
-			if (file.at(1).toString() == "installer")
+
+			QString extension = file.at(0).toString();
+			QString part = file.at(1).toString();
+			QString checksum = file.at(2).toString();
+
+			// insane form of mcver is used here
+			QString longVersion = fVersion->mcver + "-" + fVersion->jobbuildver;
+			if (!fVersion->branch.isEmpty())
+			{
+				longVersion = longVersion + "-" + fVersion->branch;
+			}
+			QString filename = artifact + "-" + longVersion + "-" + part + "." + extension;
+
+			QString url = QString("%1/%2/%3")
+							  .arg(webpath)
+							  .arg(longVersion)
+							  .arg(filename);
+
+			if (part == "installer")
 			{
-				fVersion->installer_url = QString("%1/%2-%3/%4-%2-%3-installer.%5").arg(
-					webpath, fVersion->mcver, fVersion->jobbuildver, artifact,
-					file.at(0).toString());
-				installer_filename = QString("%1-%2-%3-installer.%4").arg(
-					artifact, fVersion->mcver, fVersion->jobbuildver, file.at(0).toString());
+				fVersion->installer_url = url;
+				installer_filename = filename;
 			}
-			else if (file.at(1).toString() == "universal")
+			else if (part == "universal")
 			{
-				fVersion->universal_url = QString("%1/%2-%3/%4-%2-%3-universal.%5").arg(
-					webpath, fVersion->mcver, fVersion->jobbuildver, artifact,
-					file.at(0).toString());
-				filename = QString("%1-%2-%3-universal.%4").arg(
-					artifact, fVersion->mcver, fVersion->jobbuildver, file.at(0).toString());
+				fVersion->universal_url = url;
+				universal_filename = filename;
 			}
-			else if (file.at(1).toString() == "changelog")
+			else if (part == "changelog")
 			{
-				fVersion->changelog_url = QString("%1/%2-%3/%4-%2-%3-changelog.%5").arg(
-					webpath, fVersion->mcver, fVersion->jobbuildver, artifact,
-					file.at(0).toString());
+				fVersion->changelog_url = url;
 			}
 		}
 		if (fVersion->installer_url.isEmpty() && fVersion->universal_url.isEmpty())
 		{
 			continue;
 		}
-		fVersion->filename = fVersion->installer_url.isEmpty() ? filename : installer_filename;
+		fVersion->universal_filename = universal_filename;
+		fVersion->installer_filename = installer_filename;
 		out.append(fVersion);
 	}
-
 	return true;
 }
 
@@ -425,6 +438,7 @@ void ForgeListLoadTask::listFailed()
 		QLOG_ERROR() << "Getting forge version list failed for reasons unknown.";
 	}
 }
+
 void ForgeListLoadTask::gradleListFailed()
 {
 	auto reply = gradleListDownload->m_reply;
diff --git a/logic/lists/ForgeVersionList.h b/logic/forge/ForgeVersionList.h
index b19d3f56..477edb3d 100644
--- a/logic/lists/ForgeVersionList.h
+++ b/logic/forge/ForgeVersionList.h
@@ -18,57 +18,12 @@
 #include <QObject>
 #include <QAbstractListModel>
 #include <QUrl>
-
 #include <QNetworkReply>
-#include "BaseVersionList.h"
+
+#include "logic/BaseVersionList.h"
 #include "logic/tasks/Task.h"
 #include "logic/net/NetJob.h"
-
-class ForgeVersion;
-typedef std::shared_ptr<ForgeVersion> ForgeVersionPtr;
-
-struct ForgeVersion : public BaseVersion
-{
-	virtual QString descriptor() override
-	{
-		return filename;
-	}
-	;
-	virtual QString name() override
-	{
-		return "Forge " + jobbuildver;
-	}
-	;
-	virtual QString typeString() const override
-	{
-		if (installer_url.isEmpty())
-			return "Universal";
-		else
-			return "Installer";
-	}
-
-	virtual bool operator<(BaseVersion &a) override
-	{
-		ForgeVersion *pa = dynamic_cast<ForgeVersion *>(&a);
-		if(!pa)
-			return true;
-		return m_buildnr < pa->m_buildnr;
-	}
-	virtual bool operator>(BaseVersion &a) override
-	{
-		ForgeVersion *pa = dynamic_cast<ForgeVersion *>(&a);
-		if(!pa)
-			return false;
-		return m_buildnr > pa->m_buildnr;
-	}
-	int m_buildnr = 0;
-	QString universal_url;
-	QString changelog_url;
-	QString installer_url;
-	QString jobbuildver;
-	QString mcver;
-	QString filename;
-};
+#include "logic/forge/ForgeVersion.h"
 
 class ForgeVersionList : public BaseVersionList
 {
@@ -86,6 +41,8 @@ public:
 
 	virtual BaseVersionPtr getLatestStable() const;
 
+	ForgeVersionPtr findVersionByVersionNr(QString version);
+
 	virtual QVariant data(const QModelIndex &index, int role) const;
 	virtual QVariant headerData(int section, Qt::Orientation orientation, int role) const;
 	virtual int columnCount(const QModelIndex &parent) const;
diff --git a/logic/net/ForgeXzDownload.cpp b/logic/forge/ForgeXzDownload.cpp
index 359ad858..359ad858 100644
--- a/logic/net/ForgeXzDownload.cpp
+++ b/logic/forge/ForgeXzDownload.cpp
diff --git a/logic/net/ForgeXzDownload.h b/logic/forge/ForgeXzDownload.h
index 7bdfb6d9..f2564380 100644
--- a/logic/net/ForgeXzDownload.h
+++ b/logic/forge/ForgeXzDownload.h
@@ -15,8 +15,8 @@
 
 #pragma once
 
-#include "NetAction.h"
-#include "HttpMetaCache.h"
+#include "logic/net/NetAction.h"
+#include "logic/net/HttpMetaCache.h"
 #include <QFile>
 #include <QTemporaryFile>
 #include "ForgeMirror.h"
diff --git a/logic/LegacyForge.cpp b/logic/forge/LegacyForge.cpp
index 94212ae4..94212ae4 100644
--- a/logic/LegacyForge.cpp
+++ b/logic/forge/LegacyForge.cpp
diff --git a/logic/LegacyForge.h b/logic/forge/LegacyForge.h
index f4165ffa..ec49f63c 100644
--- a/logic/LegacyForge.h
+++ b/logic/forge/LegacyForge.h
@@ -15,7 +15,7 @@
 
 #pragma once
 
-#include "Mod.h"
+#include "logic/Mod.h"
 
 class MinecraftForge : public Mod
 {
diff --git a/logic/JavaChecker.cpp b/logic/java/JavaChecker.cpp
index b87ee3d5..b87ee3d5 100644
--- a/logic/JavaChecker.cpp
+++ b/logic/java/JavaChecker.cpp
diff --git a/logic/JavaChecker.h b/logic/java/JavaChecker.h
index e19895f7..e19895f7 100644
--- a/logic/JavaChecker.h
+++ b/logic/java/JavaChecker.h
diff --git a/logic/JavaCheckerJob.cpp b/logic/java/JavaCheckerJob.cpp
index b0aea758..b0aea758 100644
--- a/logic/JavaCheckerJob.cpp
+++ b/logic/java/JavaCheckerJob.cpp
diff --git a/logic/JavaCheckerJob.h b/logic/java/JavaCheckerJob.h
index 132a92d4..132a92d4 100644
--- a/logic/JavaCheckerJob.h
+++ b/logic/java/JavaCheckerJob.h
diff --git a/logic/JavaUtils.cpp b/logic/java/JavaUtils.cpp
index 3a3046bd..09719c73 100644
--- a/logic/JavaUtils.cpp
+++ b/logic/java/JavaUtils.cpp
@@ -16,7 +16,6 @@
 #include <QStringList>
 #include <QString>
 #include <QDir>
-#include <QMessageBox>
 #include <QStringList>
 
 #include <setting.h>
@@ -24,11 +23,10 @@
 
 #include "MultiMC.h"
 
-#include "JavaUtils.h"
 #include "logger/QsLog.h"
-#include "gui/dialogs/VersionSelectDialog.h"
-#include "JavaCheckerJob.h"
-#include "lists/JavaVersionList.h"
+#include "logic/java/JavaUtils.h"
+#include "logic/java/JavaCheckerJob.h"
+#include "logic/java/JavaVersionList.h"
 
 JavaUtils::JavaUtils()
 {
@@ -124,7 +122,7 @@ QList<JavaVersionPtr> JavaUtils::FindJavaFromRegistryKey(DWORD keyType, QString
 							javaVersion->id = subKeyName;
 							javaVersion->arch = archType;
 							javaVersion->path =
-								QDir(PathCombine(value, "bin")).absoluteFilePath("java.exe");
+								QDir(PathCombine(value, "bin")).absoluteFilePath("javaw.exe");
 							javas.append(javaVersion);
 						}
 
@@ -154,12 +152,12 @@ QList<QString> JavaUtils::FindJavaPaths()
 		KEY_WOW64_32KEY, "SOFTWARE\\JavaSoft\\Java Development Kit");
 
 	java_candidates.append(JRE64s);
-	java_candidates.append(MakeJavaPtr("C:/Program Files/Java/jre7/bin/java.exe"));
-	java_candidates.append(MakeJavaPtr("C:/Program Files/Java/jre6/bin/java.exe"));
+	java_candidates.append(MakeJavaPtr("C:/Program Files/Java/jre7/bin/javaw.exe"));
+	java_candidates.append(MakeJavaPtr("C:/Program Files/Java/jre6/bin/javaw.exe"));
 	java_candidates.append(JDK64s);
 	java_candidates.append(JRE32s);
-	java_candidates.append(MakeJavaPtr("C:/Program Files (x86)/Java/jre7/bin/java.exe"));
-	java_candidates.append(MakeJavaPtr("C:/Program Files (x86)/Java/jre6/bin/java.exe"));
+	java_candidates.append(MakeJavaPtr("C:/Program Files (x86)/Java/jre7/bin/javaw.exe"));
+	java_candidates.append(MakeJavaPtr("C:/Program Files (x86)/Java/jre6/bin/javaw.exe"));
 	java_candidates.append(JDK32s);
 	java_candidates.append(MakeJavaPtr(this->GetDefaultJava()->path));
 
diff --git a/logic/JavaUtils.h b/logic/java/JavaUtils.h
index 22a68ef3..af92100f 100644
--- a/logic/JavaUtils.h
+++ b/logic/java/JavaUtils.h
@@ -21,7 +21,7 @@
 #include <osutils.h>
 #include "JavaCheckerJob.h"
 #include "JavaChecker.h"
-#include "lists/JavaVersionList.h"
+#include "JavaVersionList.h"
 
 #if WINDOWS
 #include <windows.h>
diff --git a/logic/lists/JavaVersionList.cpp b/logic/java/JavaVersionList.cpp
index 4fd0bc19..dcb6ced6 100644
--- a/logic/lists/JavaVersionList.cpp
+++ b/logic/java/JavaVersionList.cpp
@@ -13,16 +13,16 @@
  * limitations under the License.
  */
 
-#include "JavaVersionList.h"
-#include "MultiMC.h"
-
 #include <QtNetwork>
 #include <QtXml>
 #include <QRegExp>
 
+#include "MultiMC.h"
 #include "logger/QsLog.h"
-#include "logic/JavaCheckerJob.h"
-#include "logic/JavaUtils.h"
+
+#include "logic/java/JavaVersionList.h"
+#include "logic/java/JavaCheckerJob.h"
+#include "logic/java/JavaUtils.h"
 
 JavaVersionList::JavaVersionList(QObject *parent) : BaseVersionList(parent)
 {
diff --git a/logic/lists/JavaVersionList.h b/logic/java/JavaVersionList.h
index e6cc8e5f..a46f33a2 100644
--- a/logic/lists/JavaVersionList.h
+++ b/logic/java/JavaVersionList.h
@@ -18,9 +18,9 @@
 #include <QObject>
 #include <QAbstractListModel>
 
-#include "BaseVersionList.h"
+#include "logic/BaseVersionList.h"
 #include "logic/tasks/Task.h"
-#include "logic/JavaCheckerJob.h"
+#include "logic/java/JavaCheckerJob.h"
 
 class JavaListLoadTask;
 
diff --git a/logic/lists/MinecraftVersionList.cpp b/logic/lists/MinecraftVersionList.cpp
deleted file mode 100644
index b9d60c61..00000000
--- a/logic/lists/MinecraftVersionList.cpp
+++ /dev/null
@@ -1,290 +0,0 @@
-/* Copyright 2013 MultiMC Contributors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include "MinecraftVersionList.h"
-#include "MultiMC.h"
-#include "logic/net/URLConstants.h"
-
-#include <QtXml>
-
-#include <QJsonDocument>
-#include <QJsonObject>
-#include <QJsonArray>
-#include <QJsonValue>
-#include <QJsonParseError>
-
-#include <QtAlgorithms>
-
-#include <QtNetwork>
-
-MinecraftVersionList::MinecraftVersionList(QObject *parent) : BaseVersionList(parent)
-{
-}
-
-Task *MinecraftVersionList::getLoadTask()
-{
-	return new MCVListLoadTask(this);
-}
-
-bool MinecraftVersionList::isLoaded()
-{
-	return m_loaded;
-}
-
-const BaseVersionPtr MinecraftVersionList::at(int i) const
-{
-	return m_vlist.at(i);
-}
-
-int MinecraftVersionList::count() const
-{
-	return m_vlist.count();
-}
-
-static bool cmpVersions(BaseVersionPtr first, BaseVersionPtr second)
-{
-	auto left = std::dynamic_pointer_cast<MinecraftVersion>(first);
-	auto right = std::dynamic_pointer_cast<MinecraftVersion>(second);
-	return left->timestamp > right->timestamp;
-}
-
-void MinecraftVersionList::sortInternal()
-{
-	qSort(m_vlist.begin(), m_vlist.end(), cmpVersions);
-}
-
-void MinecraftVersionList::sort()
-{
-	beginResetModel();
-	sortInternal();
-	endResetModel();
-}
-
-BaseVersionPtr MinecraftVersionList::getLatestStable() const
-{
-	for (int i = 0; i < m_vlist.length(); i++)
-	{
-		auto ver = std::dynamic_pointer_cast<MinecraftVersion>(m_vlist.at(i));
-		if (ver->is_latest && !ver->is_snapshot)
-		{
-			return m_vlist.at(i);
-		}
-	}
-	return BaseVersionPtr();
-}
-
-void MinecraftVersionList::updateListData(QList<BaseVersionPtr> versions)
-{
-	beginResetModel();
-	m_vlist = versions;
-	m_loaded = true;
-	sortInternal();
-	endResetModel();
-}
-
-inline QDomElement getDomElementByTagName(QDomElement parent, QString tagname)
-{
-	QDomNodeList elementList = parent.elementsByTagName(tagname);
-	if (elementList.count())
-		return elementList.at(0).toElement();
-	else
-		return QDomElement();
-}
-
-inline QDateTime timeFromS3Time(QString str)
-{
-	return QDateTime::fromString(str, Qt::ISODate);
-}
-
-MCVListLoadTask::MCVListLoadTask(MinecraftVersionList *vlist)
-{
-	m_list = vlist;
-	m_currentStable = NULL;
-	vlistReply = nullptr;
-	legacyWhitelist.insert("1.5.2");
-	legacyWhitelist.insert("1.5.1");
-	legacyWhitelist.insert("1.5");
-	legacyWhitelist.insert("1.4.7");
-	legacyWhitelist.insert("1.4.6");
-	legacyWhitelist.insert("1.4.5");
-	legacyWhitelist.insert("1.4.4");
-	legacyWhitelist.insert("1.4.3");
-	legacyWhitelist.insert("1.4.2");
-	legacyWhitelist.insert("1.4.1");
-	legacyWhitelist.insert("1.4");
-	legacyWhitelist.insert("1.3.2");
-	legacyWhitelist.insert("1.3.1");
-	legacyWhitelist.insert("1.3");
-	legacyWhitelist.insert("1.2.5");
-	legacyWhitelist.insert("1.2.4");
-	legacyWhitelist.insert("1.2.3");
-	legacyWhitelist.insert("1.2.2");
-	legacyWhitelist.insert("1.2.1");
-	legacyWhitelist.insert("1.1");
-	legacyWhitelist.insert("1.0.1");
-	legacyWhitelist.insert("1.0");
-}
-
-MCVListLoadTask::~MCVListLoadTask()
-{
-}
-
-void MCVListLoadTask::executeTask()
-{
-	setStatus(tr("Loading instance version list..."));
-	auto worker = MMC->qnam();
-	vlistReply = worker->get(QNetworkRequest(QUrl("http://" + URLConstants::AWS_DOWNLOAD_VERSIONS + "versions.json")));
-	connect(vlistReply, SIGNAL(finished()), this, SLOT(list_downloaded()));
-}
-
-void MCVListLoadTask::list_downloaded()
-{
-	if (vlistReply->error() != QNetworkReply::NoError)
-	{
-		vlistReply->deleteLater();
-		emitFailed("Failed to load Minecraft main version list" + vlistReply->errorString());
-		return;
-	}
-
-	QJsonParseError jsonError;
-	QJsonDocument jsonDoc = QJsonDocument::fromJson(vlistReply->readAll(), &jsonError);
-	vlistReply->deleteLater();
-
-	if (jsonError.error != QJsonParseError::NoError)
-	{
-		emitFailed("Error parsing version list JSON:" + jsonError.errorString());
-		return;
-	}
-
-	if (!jsonDoc.isObject())
-	{
-		emitFailed("Error parsing version list JSON: jsonDoc is not an object");
-		return;
-	}
-
-	QJsonObject root = jsonDoc.object();
-
-	// Get the ID of the latest release and the latest snapshot.
-	if (!root.value("latest").isObject())
-	{
-		emitFailed("Error parsing version list JSON: version list is missing 'latest' object");
-		return;
-	}
-
-	QJsonObject latest = root.value("latest").toObject();
-
-	QString latestReleaseID = latest.value("release").toString("");
-	QString latestSnapshotID = latest.value("snapshot").toString("");
-	if (latestReleaseID.isEmpty())
-	{
-		emitFailed("Error parsing version list JSON: latest release field is missing");
-		return;
-	}
-	if (latestSnapshotID.isEmpty())
-	{
-		emitFailed("Error parsing version list JSON: latest snapshot field is missing");
-		return;
-	}
-
-	// Now, get the array of versions.
-	if (!root.value("versions").isArray())
-	{
-		emitFailed(
-			"Error parsing version list JSON: version list object is missing 'versions' array");
-		return;
-	}
-	QJsonArray versions = root.value("versions").toArray();
-
-	QList<BaseVersionPtr> tempList;
-	for (int i = 0; i < versions.count(); i++)
-	{
-		bool is_snapshot = false;
-		bool is_latest = false;
-
-		// Load the version info.
-		if (!versions[i].isObject())
-		{
-			// FIXME: log this somewhere
-			continue;
-		}
-		QJsonObject version = versions[i].toObject();
-		QString versionID = version.value("id").toString("");
-		QString versionTimeStr = version.value("releaseTime").toString("");
-		QString versionTypeStr = version.value("type").toString("");
-		if (versionID.isEmpty() || versionTimeStr.isEmpty() || versionTypeStr.isEmpty())
-		{
-			// FIXME: log this somewhere
-			continue;
-		}
-
-		// Parse the timestamp.
-		QDateTime versionTime = timeFromS3Time(versionTimeStr);
-		if (!versionTime.isValid())
-		{
-			// FIXME: log this somewhere
-			continue;
-		}
-		// Parse the type.
-		MinecraftVersion::VersionType versionType;
-		// OneSix or Legacy. use filter to determine type
-		if (versionTypeStr == "release")
-		{
-			versionType = legacyWhitelist.contains(versionID) ? MinecraftVersion::Legacy
-															  : MinecraftVersion::OneSix;
-			is_latest = (versionID == latestReleaseID);
-			is_snapshot = false;
-		}
-		else if (versionTypeStr == "snapshot") // It's a snapshot... yay
-		{
-			versionType = legacyWhitelist.contains(versionID) ? MinecraftVersion::Legacy
-															  : MinecraftVersion::OneSix;
-			is_latest = (versionID == latestSnapshotID);
-			is_snapshot = true;
-		}
-		else if (versionTypeStr == "old_alpha")
-		{
-			versionType = MinecraftVersion::Nostalgia;
-			is_latest = false;
-			is_snapshot = false;
-		}
-		else if (versionTypeStr == "old_beta")
-		{
-			versionType = MinecraftVersion::Legacy;
-			is_latest = false;
-			is_snapshot = false;
-		}
-		else
-		{
-			// FIXME: log this somewhere
-			continue;
-		}
-		// Get the download URL.
-		QString dlUrl = "http://" + URLConstants::AWS_DOWNLOAD_VERSIONS + versionID + "/";
-
-		// Now, we construct the version object and add it to the list.
-		std::shared_ptr<MinecraftVersion> mcVersion(new MinecraftVersion());
-		mcVersion->m_name = mcVersion->m_descriptor = versionID;
-		mcVersion->timestamp = versionTime.toMSecsSinceEpoch();
-		mcVersion->download_url = dlUrl;
-		mcVersion->is_latest = is_latest;
-		mcVersion->is_snapshot = is_snapshot;
-		mcVersion->type = versionType;
-		tempList.append(mcVersion);
-	}
-	m_list->updateListData(tempList);
-
-	emitSucceeded();
-	return;
-}
diff --git a/logic/LiteLoaderInstaller.cpp b/logic/liteloader/LiteLoaderInstaller.cpp
index 99cc5643..ea1a4396 100644
--- a/logic/LiteLoaderInstaller.cpp
+++ b/logic/liteloader/LiteLoaderInstaller.cpp
@@ -20,11 +20,11 @@
 
 #include "logger/QsLog.h"
 
-#include "VersionFinal.h"
-#include "OneSixLibrary.h"
-#include "OneSixInstance.h"
+#include "logic/minecraft/InstanceVersion.h"
+#include "logic/minecraft/OneSixLibrary.h"
+#include "logic/OneSixInstance.h"
 #include "MultiMC.h"
-#include "lists/LiteLoaderVersionList.h"
+#include "logic/liteloader/LiteLoaderVersionList.h"
 
 LiteLoaderInstaller::LiteLoaderInstaller() : BaseInstaller()
 {
diff --git a/logic/LiteLoaderInstaller.h b/logic/liteloader/LiteLoaderInstaller.h
index 3ab5acb2..43ad6b83 100644
--- a/logic/LiteLoaderInstaller.h
+++ b/logic/liteloader/LiteLoaderInstaller.h
@@ -15,12 +15,11 @@
 
 #pragma once
 
-#include "BaseInstaller.h"
-
 #include <QString>
 #include <QMap>
 
-#include "logic/lists/LiteLoaderVersionList.h"
+#include "logic/BaseInstaller.h"
+#include "logic/liteloader/LiteLoaderVersionList.h"
 
 class LiteLoaderInstaller : public BaseInstaller
 {
diff --git a/logic/lists/LiteLoaderVersionList.cpp b/logic/liteloader/LiteLoaderVersionList.cpp
index ef95eefd..ef95eefd 100644
--- a/logic/lists/LiteLoaderVersionList.cpp
+++ b/logic/liteloader/LiteLoaderVersionList.cpp
diff --git a/logic/lists/LiteLoaderVersionList.h b/logic/liteloader/LiteLoaderVersionList.h
index bfc913e5..0aecc3e1 100644
--- a/logic/lists/LiteLoaderVersionList.h
+++ b/logic/liteloader/LiteLoaderVersionList.h
@@ -19,10 +19,10 @@
 
 #include <QString>
 #include <QStringList>
-#include "BaseVersionList.h"
-#include "logic/tasks/Task.h"
 #include "logic/BaseVersion.h"
-#include <logic/net/NetJob.h>
+#include "logic/BaseVersionList.h"
+#include "logic/tasks/Task.h"
+#include "logic/net/NetJob.h"
 
 class LLListLoadTask;
 class QNetworkReply;
diff --git a/logic/minecraft/InstanceVersion.cpp b/logic/minecraft/InstanceVersion.cpp
new file mode 100644
index 00000000..ca0e3796
--- /dev/null
+++ b/logic/minecraft/InstanceVersion.cpp
@@ -0,0 +1,537 @@
+/* Copyright 2013 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <QDebug>
+#include <QFile>
+#include <QDir>
+#include <QUuid>
+#include <QJsonDocument>
+#include <QJsonArray>
+#include <pathutils.h>
+
+#include "logic/minecraft/InstanceVersion.h"
+#include "logic/minecraft/VersionBuilder.h"
+#include "logic/OneSixInstance.h"
+
+InstanceVersion::InstanceVersion(OneSixInstance *instance, QObject *parent)
+	: QAbstractListModel(parent), m_instance(instance)
+{
+	clear();
+}
+
+void InstanceVersion::reload(const QStringList &external)
+{
+	m_externalPatches = external;
+	beginResetModel();
+	VersionBuilder::build(this, m_instance, m_externalPatches);
+	reapply(true);
+	endResetModel();
+}
+
+void InstanceVersion::clear()
+{
+	id.clear();
+	m_updateTimeString.clear();
+	m_updateTime = QDateTime();
+	m_releaseTimeString.clear();
+	m_releaseTime = QDateTime();
+	type.clear();
+	assets.clear();
+	processArguments.clear();
+	minecraftArguments.clear();
+	minimumLauncherVersion = 0xDEADBEAF;
+	mainClass.clear();
+	appletClass.clear();
+	libraries.clear();
+	tweakers.clear();
+	jarMods.clear();
+	traits.clear();
+}
+
+bool InstanceVersion::canRemove(const int index) const
+{
+	return VersionPatches.at(index)->isMoveable();
+}
+
+bool InstanceVersion::preremove(VersionPatchPtr patch)
+{
+	bool ok = true;
+	for(auto & jarmod: patch->getJarMods())
+	{
+		QString fullpath =PathCombine(m_instance->jarModsDir(), jarmod->name);
+		QFileInfo finfo (fullpath);
+		if(finfo.exists())
+			ok &= QFile::remove(fullpath);
+	}
+	return ok;
+}
+
+bool InstanceVersion::remove(const int index)
+{
+	if (!canRemove(index))
+		return false;
+	if(!preremove(VersionPatches[index]))
+	{
+		return false;
+	}
+	if(!QFile::remove(VersionPatches.at(index)->getPatchFilename()))
+		return false;
+	beginRemoveRows(QModelIndex(), index, index);
+	VersionPatches.removeAt(index);
+	endRemoveRows();
+	reapply(true);
+	saveCurrentOrder();
+	return true;
+}
+
+bool InstanceVersion::remove(const QString id)
+{
+	int i = 0;
+	for (auto patch : VersionPatches)
+	{
+		if (patch->getPatchID() == id)
+		{
+			return remove(i);
+		}
+		i++;
+	}
+	return false;
+}
+
+QString InstanceVersion::versionFileId(const int index) const
+{
+	if (index < 0 || index >= VersionPatches.size())
+	{
+		return QString();
+	}
+	return VersionPatches.at(index)->getPatchID();
+}
+
+VersionPatchPtr InstanceVersion::versionPatch(const QString &id)
+{
+	for (auto file : VersionPatches)
+	{
+		if (file->getPatchID() == id)
+		{
+			return file;
+		}
+	}
+	return 0;
+}
+
+VersionPatchPtr InstanceVersion::versionPatch(int index)
+{
+	if(index < 0 || index >= VersionPatches.size())
+		return 0;
+	return VersionPatches[index];
+}
+
+
+bool InstanceVersion::hasJarMods()
+{
+	return !jarMods.isEmpty();
+}
+
+bool InstanceVersion::hasFtbPack()
+{
+	return versionPatch("org.multimc.ftb.pack.json") != nullptr;
+}
+
+bool InstanceVersion::removeFtbPack()
+{
+	return remove("org.multimc.ftb.pack.json");
+}
+
+bool InstanceVersion::isVanilla()
+{
+	QDir patches(PathCombine(m_instance->instanceRoot(), "patches/"));
+	if(VersionPatches.size() > 1)
+		return false;
+	if(QFile::exists(PathCombine(m_instance->instanceRoot(), "custom.json")))
+		return false;
+	if(QFile::exists(PathCombine(m_instance->instanceRoot(), "version.json")))
+		return false;
+	return true;
+}
+
+bool InstanceVersion::revertToVanilla()
+{
+	beginResetModel();
+	// remove custom.json, if present
+	QString customPath = PathCombine(m_instance->instanceRoot(), "custom.json");
+	if(QFile::exists(customPath))
+	{
+		if(!QFile::remove(customPath))
+		{
+			endResetModel();
+			return false;
+		}
+	}
+	// remove version.json, if present
+	QString versionPath = PathCombine(m_instance->instanceRoot(), "version.json");
+	if(QFile::exists(versionPath))
+	{
+		if(!QFile::remove(versionPath))
+		{
+			endResetModel();
+			return false;
+		}
+	}
+	// remove patches, if present
+	auto it = VersionPatches.begin();
+	while (it != VersionPatches.end())
+	{
+		if ((*it)->isMoveable())
+		{
+			if(!preremove(*it))
+			{
+				endResetModel();
+				saveCurrentOrder();
+				return false;
+			}
+			if(!QFile::remove((*it)->getPatchFilename()))
+			{
+				endResetModel();
+				saveCurrentOrder();
+				return false;
+			}
+			it = VersionPatches.erase(it);
+		}
+		else
+			it++;
+	}
+	reapply(true);
+	endResetModel();
+	saveCurrentOrder();
+	return true;
+}
+
+bool InstanceVersion::hasDeprecatedVersionFiles()
+{
+	if(QFile::exists(PathCombine(m_instance->instanceRoot(), "custom.json")))
+		return true;
+	if(QFile::exists(PathCombine(m_instance->instanceRoot(), "version.json")))
+		return true;
+	return false;
+}
+
+bool InstanceVersion::removeDeprecatedVersionFiles()
+{
+	beginResetModel();
+	// remove custom.json, if present
+	QString customPath = PathCombine(m_instance->instanceRoot(), "custom.json");
+	if(QFile::exists(customPath))
+	{
+		if(!QFile::remove(customPath))
+		{
+			endResetModel();
+			return false;
+		}
+	}
+	// remove version.json, if present
+	QString versionPath = PathCombine(m_instance->instanceRoot(), "version.json");
+	if(QFile::exists(versionPath))
+	{
+		if(!QFile::remove(versionPath))
+		{
+			endResetModel();
+			return false;
+		}
+	}
+	endResetModel();
+	return true;
+}
+
+QList<std::shared_ptr<OneSixLibrary> > InstanceVersion::getActiveNormalLibs()
+{
+	QList<std::shared_ptr<OneSixLibrary> > output;
+	for (auto lib : libraries)
+	{
+		if (lib->isActive() && !lib->isNative())
+		{
+			output.append(lib);
+		}
+	}
+	return output;
+}
+QList<std::shared_ptr<OneSixLibrary> > InstanceVersion::getActiveNativeLibs()
+{
+	QList<std::shared_ptr<OneSixLibrary> > output;
+	for (auto lib : libraries)
+	{
+		if (lib->isActive() && lib->isNative())
+		{
+			output.append(lib);
+		}
+	}
+	return output;
+}
+
+std::shared_ptr<InstanceVersion> InstanceVersion::fromJson(const QJsonObject &obj)
+{
+	std::shared_ptr<InstanceVersion> version(new InstanceVersion(0));
+	try
+	{
+		VersionBuilder::readJsonAndApplyToVersion(version.get(), obj);
+	}
+	catch(MMCError & err)
+	{
+		return 0;
+	}
+	return version;
+}
+
+QVariant InstanceVersion::data(const QModelIndex &index, int role) const
+{
+	if (!index.isValid())
+		return QVariant();
+
+	int row = index.row();
+	int column = index.column();
+
+	if (row < 0 || row >= VersionPatches.size())
+		return QVariant();
+
+	if (role == Qt::DisplayRole)
+	{
+		switch (column)
+		{
+		case 0:
+			return VersionPatches.at(row)->getPatchName();
+		case 1:
+			return VersionPatches.at(row)->getPatchVersion();
+		default:
+			return QVariant();
+		}
+	}
+	return QVariant();
+}
+QVariant InstanceVersion::headerData(int section, Qt::Orientation orientation, int role) const
+{
+	if (orientation == Qt::Horizontal)
+	{
+		if (role == Qt::DisplayRole)
+		{
+			switch (section)
+			{
+			case 0:
+				return tr("Name");
+			case 1:
+				return tr("Version");
+			default:
+				return QVariant();
+			}
+		}
+	}
+	return QVariant();
+}
+Qt::ItemFlags InstanceVersion::flags(const QModelIndex &index) const
+{
+	if (!index.isValid())
+		return Qt::NoItemFlags;
+	return Qt::ItemIsSelectable | Qt::ItemIsEnabled;
+}
+
+int InstanceVersion::rowCount(const QModelIndex &parent) const
+{
+	return VersionPatches.size();
+}
+
+int InstanceVersion::columnCount(const QModelIndex &parent) const
+{
+	return 2;
+}
+
+void InstanceVersion::saveCurrentOrder() const
+{
+	PatchOrder order;
+	for(auto item: VersionPatches)
+	{
+		if(!item->isMoveable())
+			continue;
+		order.append(item->getPatchID());
+	}
+	VersionBuilder::writeOverrideOrders(m_instance, order);
+}
+
+void InstanceVersion::move(const int index, const MoveDirection direction)
+{
+	int theirIndex;
+	if (direction == MoveUp)
+	{
+		theirIndex = index - 1;
+	}
+	else
+	{
+		theirIndex = index + 1;
+	}
+	
+	if (index < 0 || index >= VersionPatches.size())
+		return;
+	if (theirIndex >= rowCount())
+		theirIndex = rowCount() - 1;
+	if (theirIndex == -1)
+		theirIndex = rowCount() - 1;
+	if (index == theirIndex)
+		return;
+	int togap = theirIndex > index ? theirIndex + 1 : theirIndex;
+
+	auto from = versionPatch(index);
+	auto to = versionPatch(theirIndex);
+	
+	if (!from || !to || !to->isMoveable() || !from->isMoveable())
+	{
+		return;
+	}
+	beginMoveRows(QModelIndex(), index, index, QModelIndex(), togap);
+	VersionPatches.swap(index, theirIndex);
+	endMoveRows();
+	saveCurrentOrder();
+	reapply();
+}
+void InstanceVersion::resetOrder()
+{
+	QDir(m_instance->instanceRoot()).remove("order.json");
+	reload(m_externalPatches);
+}
+
+void InstanceVersion::reapply(const bool alreadyReseting)
+{
+	clear();
+	for(auto file: VersionPatches)
+	{
+		file->applyTo(this);
+	}
+	finalize();
+}
+
+void InstanceVersion::finalize()
+{
+	// HACK: deny april fools. my head hurts enough already.
+	QDate now = QDate::currentDate();
+	bool isAprilFools = now.month() == 4 && now.day() == 1;
+	if (assets.endsWith("_af") && !isAprilFools)
+	{
+		assets = assets.left(assets.length() - 3);
+	}
+	if (assets.isEmpty())
+	{
+		assets = "legacy";
+	}
+	auto finalizeArguments = [&]( QString & minecraftArguments, const QString & processArguments ) -> void
+	{
+		if (!minecraftArguments.isEmpty())
+			return;
+		QString toCompare = processArguments.toLower();
+		if (toCompare == "legacy")
+		{
+			minecraftArguments = " ${auth_player_name} ${auth_session}";
+		}
+		else if (toCompare == "username_session")
+		{
+			minecraftArguments = "--username ${auth_player_name} --session ${auth_session}";
+		}
+		else if (toCompare == "username_session_version")
+		{
+			minecraftArguments = "--username ${auth_player_name} "
+								"--session ${auth_session} "
+								"--version ${profile_name}";
+		}
+	};
+	finalizeArguments(vanillaMinecraftArguments, vanillaProcessArguments);
+	finalizeArguments(minecraftArguments, processArguments);
+}
+
+void InstanceVersion::installJarMods(QStringList selectedFiles)
+{
+	for(auto filename: selectedFiles)
+	{
+		installJarModByFilename(filename);
+	}
+}
+
+void InstanceVersion::installJarModByFilename(QString filepath)
+{
+	QString patchDir = PathCombine(m_instance->instanceRoot(), "patches");
+	if(!ensureFolderPathExists(patchDir))
+	{
+		// THROW...
+		return;
+	}
+
+	if (!ensureFolderPathExists(m_instance->jarModsDir()))
+	{
+		// THROW...
+		return;
+	}
+
+	QFileInfo sourceInfo(filepath);
+	auto uuid = QUuid::createUuid();
+	QString id = uuid.toString().remove('{').remove('}');
+	QString target_filename = id + ".jar";
+	QString target_id = "org.multimc.jarmod." + id;
+	QString target_name = sourceInfo.completeBaseName() + " (jar mod)";
+	QString finalPath = PathCombine(m_instance->jarModsDir(), target_filename);
+
+	QFileInfo targetInfo(finalPath);
+	if(targetInfo.exists())
+	{
+		// THROW
+		return;
+	}
+
+	if (!QFile::copy(sourceInfo.absoluteFilePath(),QFileInfo(finalPath).absoluteFilePath()))
+	{
+		// THROW
+		return;
+	}
+
+	auto f = std::make_shared<VersionFile>();
+	auto jarMod = std::make_shared<Jarmod>();
+	jarMod->name = target_filename;
+	f->jarMods.append(jarMod);
+	f->name = target_name;
+	f->fileId = target_id;
+	f->order = getFreeOrderNumber();
+	
+	QFile file(PathCombine(patchDir, target_id + ".json"));
+	if (!file.open(QFile::WriteOnly))
+	{
+		QLOG_ERROR() << "Error opening" << file.fileName()
+					 << "for reading:" << file.errorString();
+		return;
+		// THROW
+	}
+	file.write(f->toJson(true).toJson());
+	file.close();
+	int index = VersionPatches.size();
+	beginInsertRows(QModelIndex(), index, index);
+	VersionPatches.append(f);
+	endInsertRows();
+	saveCurrentOrder();
+}
+
+int InstanceVersion::getFreeOrderNumber()
+{
+	int largest = 100;
+	// yes, I do realize this is dumb. The order thing itself is dumb. and to be removed next.
+	for(auto thing: VersionPatches)
+	{
+		int order = thing->getOrder();
+		if(order > largest)
+			largest = order;
+	}
+	return largest + 1;
+}
diff --git a/logic/VersionFinal.h b/logic/minecraft/InstanceVersion.h
index 41fd23bd..6b69ab47 100644
--- a/logic/VersionFinal.h
+++ b/logic/minecraft/InstanceVersion.h
@@ -23,14 +23,15 @@
 
 #include "OneSixLibrary.h"
 #include "VersionFile.h"
+#include "JarMod.h"
 
 class OneSixInstance;
 
-class VersionFinal : public QAbstractListModel
+class InstanceVersion : public QAbstractListModel
 {
 	Q_OBJECT
 public:
-	explicit VersionFinal(OneSixInstance *instance, QObject *parent = 0);
+	explicit InstanceVersion(OneSixInstance *instance, QObject *parent = 0);
 
 	virtual QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const;
 	virtual QVariant headerData(int section, Qt::Orientation orientation, int role) const;
@@ -38,22 +39,32 @@ public:
 	virtual int columnCount(const QModelIndex &parent) const;
 	virtual Qt::ItemFlags flags(const QModelIndex &index) const;
 
-	void reload(const bool onlyVanilla = false, const QStringList &external = QStringList());
+	void reload(const QStringList &external = QStringList());
 	void clear();
 
 	bool canRemove(const int index) const;
 
 	QString versionFileId(const int index) const;
 
-	// does this instance have an all overriding custom.json
-	bool isCustom();
-	// remove custom.json
-	bool revertToBase();
-	// does this instance have an FTB pack patch file?
+	// is this version unmodded vanilla minecraft?
+	bool isVanilla();
+	// remove any customizations on top of vanilla
+	bool revertToVanilla();
+	
+	// does this version consist of obsolete files?
+	bool hasDeprecatedVersionFiles();
+	// remove obsolete files
+	bool removeDeprecatedVersionFiles();
+	
+	// does this version have an FTB pack patch file?
 	bool hasFtbPack();
 	// remove FTB pack
 	bool removeFtbPack();
 	
+	// does this version have any jar mods?
+	bool hasJarMods();
+	void installJarMods(QStringList selectedFiles);
+	void installJarModByFilename(QString filepath);
 
 	enum MoveDirection { MoveUp, MoveDown };
 	void move(const int index, const MoveDirection direction);
@@ -72,16 +83,24 @@ public:
 	QList<std::shared_ptr<OneSixLibrary>> getActiveNormalLibs();
 	QList<std::shared_ptr<OneSixLibrary>> getActiveNativeLibs();
 
-	static std::shared_ptr<VersionFinal> fromJson(const QJsonObject &obj);
+	static std::shared_ptr<InstanceVersion> fromJson(const QJsonObject &obj);
 
+private:
+	bool preremove(VersionPatchPtr patch);
+	
 	// data members
 public:
 	/// the ID - determines which jar to use! ACTUALLY IMPORTANT!
 	QString id;
-	/// Last updated time - as a string
-	QString time;
-	/// Release time - as a string
-	QString releaseTime;
+
+	/// the time this version was actually released by Mojang, as string and as QDateTime
+	QString m_releaseTimeString;
+	QDateTime m_releaseTime;
+
+	/// the time this version was last updated by Mojang, as string and as QDateTime
+	QString m_updateTimeString;
+	QDateTime m_updateTime;
+
 	/// Release type - "release" or "snapshot"
 	QString type;
 	/// Assets type - "legacy" or a version ID
@@ -91,6 +110,8 @@ public:
 	 * ex: "username_session_version"
 	 */
 	QString processArguments;
+	/// Same as above, but only for vanilla
+	QString vanillaProcessArguments;
 	/**
 	 * arguments that should be used for launching minecraft
 	 *
@@ -98,6 +119,8 @@ public:
 	 *      --version ${version_name} --gameDir ${game_directory} --assetsDir ${game_assets}"
 	 */
 	QString minecraftArguments;
+	/// Same as above, but only for vanilla
+	QString vanillaMinecraftArguments;
 	/**
 	 * the minimum launcher version required by this version ... current is 4 (at point of
 	 * writing)
@@ -111,9 +134,22 @@ public:
 	 * The main class to load first
 	 */
 	QString mainClass;
-
+	/**
+	 * The applet class, for some very old minecraft releases
+	 */
+	QString appletClass;
+	
 	/// the list of libs - both active and inactive, native and java
 	QList<std::shared_ptr<OneSixLibrary>> libraries;
+	
+	/// same, but only vanilla.
+	QList<std::shared_ptr<OneSixLibrary>> vanillaLibraries;
+
+	/// traits, collected from all the version files (version files can only add)
+	QSet<QString> traits;
+
+	/// A list of jar mods. version files can add those.
+	QList<JarmodPtr> jarMods;
 
 	/*
 	FIXME: add support for those rules here? Looks like a pile of quick hacks to me though.
@@ -136,10 +172,13 @@ public:
 	*/
 	// QList<Rule> rules;
 
-	QList<VersionFilePtr> versionFiles;
-	VersionFilePtr versionFile(const QString &id);
+	QList<VersionPatchPtr> VersionPatches;
+	VersionPatchPtr versionPatch(const QString &id);
+	VersionPatchPtr versionPatch(int index);
 
 private:
+	QStringList m_externalPatches;
 	OneSixInstance *m_instance;
-	QMap<QString, int> getExistingOrder() const;
+	void saveCurrentOrder() const;
+	int getFreeOrderNumber();
 };
diff --git a/logic/minecraft/JarMod.cpp b/logic/minecraft/JarMod.cpp
new file mode 100644
index 00000000..18a9411c
--- /dev/null
+++ b/logic/minecraft/JarMod.cpp
@@ -0,0 +1,56 @@
+#include "JarMod.h"
+#include "logic/MMCJson.h"
+using namespace MMCJson;
+
+JarmodPtr Jarmod::fromJson(const QJsonObject &libObj, const QString &filename)
+{
+	JarmodPtr out(new Jarmod());
+	if (!libObj.contains("name"))
+	{
+		throw JSONValidationError(filename +
+								  "contains a jarmod that doesn't have a 'name' field");
+	}
+	out->name = libObj.value("name").toString();
+
+	auto readString = [libObj, filename](const QString & key, QString & variable)
+	{
+		if (libObj.contains(key))
+		{
+			QJsonValue val = libObj.value(key);
+			if (!val.isString())
+			{
+				QLOG_WARN() << key << "is not a string in" << filename << "(skipping)";
+			}
+			else
+			{
+				variable = val.toString();
+			}
+		}
+	};
+
+	readString("url", out->baseurl);
+	readString("MMC-hint", out->hint);
+	readString("MMC-absoluteUrl", out->absoluteUrl);
+	if(!out->baseurl.isEmpty() && out->absoluteUrl.isEmpty())
+	{
+		out->absoluteUrl = out->baseurl + out->name;
+	}
+	return out;
+}
+
+QJsonObject Jarmod::toJson()
+{
+	QJsonObject out;
+	writeString(out, "name", name);
+	writeString(out, "url", baseurl);
+	writeString(out, "MMC-absoluteUrl", absoluteUrl);
+	writeString(out, "MMC-hint", hint);
+	return out;
+}
+
+QString Jarmod::url()
+{
+	if(!absoluteUrl.isEmpty())
+		return absoluteUrl;
+	else return baseurl + name;
+}
diff --git a/logic/minecraft/JarMod.h b/logic/minecraft/JarMod.h
new file mode 100644
index 00000000..c438dbcd
--- /dev/null
+++ b/logic/minecraft/JarMod.h
@@ -0,0 +1,18 @@
+#pragma once
+#include <QString>
+#include <QJsonObject>
+#include <memory>
+class Jarmod;
+typedef std::shared_ptr<Jarmod> JarmodPtr;
+class Jarmod
+{
+public: /* methods */
+	static JarmodPtr fromJson(const QJsonObject &libObj, const QString &filename);
+	QJsonObject toJson();
+	QString url();
+public: /* data */
+	QString name;
+	QString baseurl;
+	QString hint;
+	QString absoluteUrl;
+};
diff --git a/logic/minecraft/MinecraftVersion.cpp b/logic/minecraft/MinecraftVersion.cpp
new file mode 100644
index 00000000..488a180a
--- /dev/null
+++ b/logic/minecraft/MinecraftVersion.cpp
@@ -0,0 +1,143 @@
+#include "MinecraftVersion.h"
+#include "InstanceVersion.h"
+#include "VersionBuildError.h"
+#include "VersionBuilder.h"
+
+bool MinecraftVersion::usesLegacyLauncher()
+{
+	return m_traits.contains("legacyLaunch") || m_traits.contains("aplhaLaunch");
+}
+
+QString MinecraftVersion::descriptor()
+{
+	return m_descriptor;
+}
+
+QString MinecraftVersion::name()
+{
+	return m_name;
+}
+
+QString MinecraftVersion::typeString() const
+{
+	if(m_type == "snapshot")
+	{
+		return QObject::tr("Snapshot");
+	}
+	else if (m_type == "release")
+	{
+		return QObject::tr("Regular release");
+	}
+	else if (m_type == "old_alpha")
+	{
+		return QObject::tr("Alpha");
+	}
+	else if (m_type == "old_beta")
+	{
+		return QObject::tr("Beta");
+	}
+	else
+	{
+		return QString();
+	}
+}
+
+bool MinecraftVersion::hasJarMods()
+{
+	return false;
+}
+
+bool MinecraftVersion::isMinecraftVersion()
+{
+	return true;
+}
+
+// 1. assume the local file is good. load, check. If it's good, apply.
+// 2. if discrepancies are found, fall out and fail (impossible to apply incomplete version).
+void MinecraftVersion::applyFileTo(InstanceVersion *version)
+{
+	QFileInfo versionFile(QString("versions/%1/%1.dat").arg(m_descriptor));
+	
+	auto versionObj = VersionBuilder::parseBinaryJsonFile(versionFile);
+	versionObj->applyTo(version);
+}
+
+void MinecraftVersion::applyTo(InstanceVersion *version)
+{
+	// do we have this one cached?
+	if (m_versionSource == Local)
+	{
+		applyFileTo(version);
+		return;
+	}
+	// if not builtin, do not proceed any further.
+	if (m_versionSource != Builtin)
+	{
+		throw VersionIncomplete(QObject::tr(
+			"Minecraft version %1 could not be applied: version files are missing.").arg(m_descriptor));
+	}
+	if (!m_descriptor.isNull())
+	{
+		version->id = m_descriptor;
+	}
+	if (!m_mainClass.isNull())
+	{
+		version->mainClass = m_mainClass;
+	}
+	if (!m_appletClass.isNull())
+	{
+		version->appletClass = m_appletClass;
+	}
+	if (!m_processArguments.isNull())
+	{
+		version->vanillaProcessArguments = m_processArguments;
+		version->processArguments = m_processArguments;
+	}
+	if (!m_type.isNull())
+	{
+		version->type = m_type;
+	}
+	if (!m_releaseTimeString.isNull())
+	{
+		version->m_releaseTimeString = m_releaseTimeString;
+		version->m_releaseTime = m_releaseTime;
+	}
+	if (!m_updateTimeString.isNull())
+	{
+		version->m_updateTimeString = m_updateTimeString;
+		version->m_updateTime = m_updateTime;
+	}
+	version->traits.unite(m_traits);
+}
+
+int MinecraftVersion::getOrder()
+{
+	return order;
+}
+
+void MinecraftVersion::setOrder(int order)
+{
+	this->order = order;
+}
+
+QList<JarmodPtr> MinecraftVersion::getJarMods()
+{
+	return QList<JarmodPtr>();
+}
+
+QString MinecraftVersion::getPatchName()
+{
+	return "Minecraft";
+}
+QString MinecraftVersion::getPatchVersion()
+{
+	return m_descriptor;
+}
+QString MinecraftVersion::getPatchID()
+{
+	return "net.minecraft";
+}
+QString MinecraftVersion::getPatchFilename()
+{
+	return QString();
+}
diff --git a/logic/minecraft/MinecraftVersion.h b/logic/minecraft/MinecraftVersion.h
new file mode 100644
index 00000000..82073a97
--- /dev/null
+++ b/logic/minecraft/MinecraftVersion.h
@@ -0,0 +1,103 @@
+/* Copyright 2013 Andrew Okin
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <QStringList>
+#include <QSet>
+#include <QDateTime>
+
+#include "logic/BaseVersion.h"
+#include "VersionPatch.h"
+#include "VersionFile.h"
+#include "VersionSource.h"
+
+class InstanceVersion;
+class MinecraftVersion;
+typedef std::shared_ptr<MinecraftVersion> MinecraftVersionPtr;
+
+class MinecraftVersion : public BaseVersion, public VersionPatch
+{
+public: /* methods */
+	bool usesLegacyLauncher();
+	virtual QString descriptor() override;
+	virtual QString name() override;
+	virtual QString typeString() const override;
+	virtual bool hasJarMods() override;
+	virtual bool isMinecraftVersion() override;
+	virtual void applyTo(InstanceVersion *version) override;
+	virtual int getOrder();
+	virtual void setOrder(int order);
+	virtual QList<JarmodPtr> getJarMods() override;
+	virtual QString getPatchID() override;
+	virtual QString getPatchVersion() override;
+	virtual QString getPatchName() override;
+	virtual QString getPatchFilename() override;
+	bool needsUpdate()
+	{
+		return m_versionSource == Remote;
+	}
+	bool hasUpdate()
+	{
+		return m_versionSource == Remote || (m_versionSource == Local && upstreamUpdate);
+	}
+
+private: /* methods */
+	void applyFileTo(InstanceVersion *version);
+
+public: /* data */
+	/// The URL that this version will be downloaded from. maybe.
+	QString download_url;
+
+	VersionSource m_versionSource = Builtin;
+
+	/// the human readable version name
+	QString m_name;
+
+	/// the version ID.
+	QString m_descriptor;
+
+	/// version traits. added by MultiMC
+	QSet<QString> m_traits;
+
+	/// The main class this version uses (if any, can be empty).
+	QString m_mainClass;
+
+	/// The applet class this version uses (if any, can be empty).
+	QString m_appletClass;
+
+	/// The process arguments used by this version
+	QString m_processArguments;
+
+	/// The type of this release
+	QString m_type;
+
+	/// the time this version was actually released by Mojang, as string and as QDateTime
+	QString m_releaseTimeString;
+	QDateTime m_releaseTime;
+
+	/// the time this version was last updated by Mojang, as string and as QDateTime
+	QString m_updateTimeString;
+	QDateTime m_updateTime;
+
+	/// MD5 hash of the minecraft jar
+	QString m_jarChecksum;
+
+	/// order of this file... default = -2
+	int order = -2;
+	
+	/// an update available from Mojang
+	MinecraftVersionPtr upstreamUpdate;
+};
diff --git a/logic/minecraft/MinecraftVersionList.cpp b/logic/minecraft/MinecraftVersionList.cpp
new file mode 100644
index 00000000..3aa1ac01
--- /dev/null
+++ b/logic/minecraft/MinecraftVersionList.cpp
@@ -0,0 +1,602 @@
+/* Copyright 2013 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <QtXml>
+#include "logic/MMCJson.h"
+#include <QtAlgorithms>
+#include <QtNetwork>
+
+#include "MultiMC.h"
+#include "MMCError.h"
+
+#include "MinecraftVersionList.h"
+#include "logic/net/URLConstants.h"
+
+#include "ParseUtils.h"
+#include "VersionBuilder.h"
+#include <logic/VersionFilterData.h>
+#include <pathutils.h>
+
+static const char * localVersionCache = "versions/versions.dat";
+
+class ListLoadError : public MMCError
+{
+public:
+	ListLoadError(QString cause) : MMCError(cause) {};
+	virtual ~ListLoadError() noexcept
+	{
+	}
+};
+
+MinecraftVersionList::MinecraftVersionList(QObject *parent) : BaseVersionList(parent)
+{
+	loadBuiltinList();
+	loadCachedList();
+}
+
+Task *MinecraftVersionList::getLoadTask()
+{
+	return new MCVListLoadTask(this);
+}
+
+bool MinecraftVersionList::isLoaded()
+{
+	return m_loaded;
+}
+
+const BaseVersionPtr MinecraftVersionList::at(int i) const
+{
+	return m_vlist.at(i);
+}
+
+int MinecraftVersionList::count() const
+{
+	return m_vlist.count();
+}
+
+static bool cmpVersions(BaseVersionPtr first, BaseVersionPtr second)
+{
+	auto left = std::dynamic_pointer_cast<MinecraftVersion>(first);
+	auto right = std::dynamic_pointer_cast<MinecraftVersion>(second);
+	return left->m_releaseTime > right->m_releaseTime;
+}
+
+void MinecraftVersionList::sortInternal()
+{
+	qSort(m_vlist.begin(), m_vlist.end(), cmpVersions);
+}
+
+void MinecraftVersionList::loadCachedList()
+{
+	QFile localIndex(localVersionCache);
+	if (!localIndex.exists())
+	{
+		return;
+	}
+	if (!localIndex.open(QIODevice::ReadOnly))
+	{
+		// FIXME: this is actually a very bad thing! How do we deal with this?
+		QLOG_ERROR() << "The minecraft version cache can't be read.";
+		return;
+	}
+	auto data = localIndex.readAll();
+	try
+	{
+		localIndex.close();
+		QJsonDocument jsonDoc = QJsonDocument::fromBinaryData(data);
+		if (jsonDoc.isNull())
+		{
+			throw ListLoadError(tr("Error reading the version list."));
+		}
+		loadMojangList(jsonDoc, Local);
+	}
+	catch (MMCError &e)
+	{
+		// the cache has gone bad for some reason... flush it.
+		QLOG_ERROR() << "The minecraft version cache is corrupted. Flushing cache.";
+		localIndex.remove();
+		return;
+	}
+	m_hasLocalIndex = true;
+}
+
+void MinecraftVersionList::loadBuiltinList()
+{
+	QLOG_INFO() << "Loading builtin version list.";
+	// grab the version list data from internal resources.
+	QResource versionList(":/versions/minecraft.json");
+	QFile filez(versionList.absoluteFilePath());
+	filez.open(QIODevice::ReadOnly);
+	auto data = filez.readAll();
+
+	// parse the data as json
+	QJsonParseError jsonError;
+	QJsonDocument jsonDoc = QJsonDocument::fromJson(data, &jsonError);
+	QJsonObject root = jsonDoc.object();
+
+	// parse all the versions
+	for (const auto version : MMCJson::ensureArray(root.value("versions")))
+	{
+		QJsonObject versionObj = version.toObject();
+		QString versionID = versionObj.value("id").toString("");
+		QString versionTypeStr = versionObj.value("type").toString("");
+		if (versionID.isEmpty() || versionTypeStr.isEmpty())
+		{
+			QLOG_ERROR() << "Parsed version is missing ID or type";
+			continue;
+		}
+
+		if (g_VersionFilterData.legacyBlacklist.contains(versionID))
+		{
+			QLOG_WARN() << "Blacklisted legacy version ignored: " << versionID;
+			continue;
+		}
+
+		// Now, we construct the version object and add it to the list.
+		std::shared_ptr<MinecraftVersion> mcVersion(new MinecraftVersion());
+		mcVersion->m_name = mcVersion->m_descriptor = versionID;
+
+		// Parse the timestamp.
+		if (!parse_timestamp(versionObj.value("releaseTime").toString(""),
+							 mcVersion->m_releaseTimeString, mcVersion->m_releaseTime))
+		{
+			QLOG_ERROR() << "Error while parsing version" << versionID
+						 << ": invalid version timestamp";
+			continue;
+		}
+
+		// Get the download URL.
+		mcVersion->download_url =
+			"http://" + URLConstants::AWS_DOWNLOAD_VERSIONS + versionID + "/";
+
+		mcVersion->m_versionSource = Builtin;
+		mcVersion->m_type = versionTypeStr;
+		mcVersion->m_appletClass = versionObj.value("appletClass").toString("");
+		mcVersion->m_mainClass = versionObj.value("mainClass").toString("");
+		mcVersion->m_jarChecksum = versionObj.value("checksum").toString("");
+		mcVersion->m_processArguments = versionObj.value("processArguments").toString("legacy");
+		if (versionObj.contains("+traits"))
+		{
+			for (auto traitVal : MMCJson::ensureArray(versionObj.value("+traits")))
+			{
+				mcVersion->m_traits.insert(MMCJson::ensureString(traitVal));
+			}
+		}
+		m_lookup[versionID] = mcVersion;
+		m_vlist.append(mcVersion);
+	}
+}
+
+void MinecraftVersionList::loadMojangList(QJsonDocument jsonDoc, VersionSource source)
+{
+	QLOG_INFO() << "Loading" << ((source == Remote) ? "remote" : "local") << "version list.";
+
+	if (!jsonDoc.isObject())
+	{
+		throw ListLoadError(tr("Error parsing version list JSON: jsonDoc is not an object"));
+	}
+
+	QJsonObject root = jsonDoc.object();
+
+	try
+	{
+		QJsonObject latest = MMCJson::ensureObject(root.value("latest"));
+		m_latestReleaseID = MMCJson::ensureString(latest.value("release"));
+		m_latestSnapshotID = MMCJson::ensureString(latest.value("snapshot"));
+	}
+	catch (MMCError &err)
+	{
+		QLOG_ERROR()
+			<< tr("Error parsing version list JSON: couldn't determine latest versions");
+	}
+
+	// Now, get the array of versions.
+	if (!root.value("versions").isArray())
+	{
+		throw ListLoadError(tr("Error parsing version list JSON: version list object is "
+							   "missing 'versions' array"));
+	}
+	QJsonArray versions = root.value("versions").toArray();
+
+	QList<BaseVersionPtr> tempList;
+	for (auto version : versions)
+	{
+		// Load the version info.
+		if (!version.isObject())
+		{
+			QLOG_ERROR() << "Error while parsing version list : invalid JSON structure";
+			continue;
+		}
+
+		QJsonObject versionObj = version.toObject();
+		QString versionID = versionObj.value("id").toString("");
+		if (versionID.isEmpty())
+		{
+			QLOG_ERROR() << "Error while parsing version : version ID is missing";
+			continue;
+		}
+
+		if (g_VersionFilterData.legacyBlacklist.contains(versionID))
+		{
+			QLOG_WARN() << "Blacklisted legacy version ignored: " << versionID;
+			continue;
+		}
+
+		// Now, we construct the version object and add it to the list.
+		std::shared_ptr<MinecraftVersion> mcVersion(new MinecraftVersion());
+		mcVersion->m_name = mcVersion->m_descriptor = versionID;
+
+		if (!parse_timestamp(versionObj.value("releaseTime").toString(""),
+							 mcVersion->m_releaseTimeString, mcVersion->m_releaseTime))
+		{
+			QLOG_ERROR() << "Error while parsing version" << versionID
+						 << ": invalid release timestamp";
+			continue;
+		}
+		if (!parse_timestamp(versionObj.value("time").toString(""),
+							 mcVersion->m_updateTimeString, mcVersion->m_updateTime))
+		{
+			QLOG_ERROR() << "Error while parsing version" << versionID
+						 << ": invalid update timestamp";
+			continue;
+		}
+
+		if (mcVersion->m_releaseTime < g_VersionFilterData.legacyCutoffDate)
+		{
+			continue;
+		}
+
+		// depends on where we load the version from -- network request or local file?
+		mcVersion->m_versionSource = source;
+
+		QString dlUrl = "http://" + URLConstants::AWS_DOWNLOAD_VERSIONS + versionID + "/";
+		mcVersion->download_url = dlUrl;
+		QString versionTypeStr = versionObj.value("type").toString("");
+		if (versionTypeStr.isEmpty())
+		{
+			// FIXME: log this somewhere
+			continue;
+		}
+		// OneSix or Legacy. use filter to determine type
+		if (versionTypeStr == "release")
+		{
+		}
+		else if (versionTypeStr == "snapshot") // It's a snapshot... yay
+		{
+		}
+		else if (versionTypeStr == "old_alpha")
+		{
+		}
+		else if (versionTypeStr == "old_beta")
+		{
+		}
+		else
+		{
+			// FIXME: log this somewhere
+			continue;
+		}
+		mcVersion->m_type = versionTypeStr;
+		tempList.append(mcVersion);
+	}
+	updateListData(tempList);
+	if(source == Remote)
+	{
+		m_loaded = true;
+	}
+}
+
+void MinecraftVersionList::sort()
+{
+	beginResetModel();
+	sortInternal();
+	endResetModel();
+}
+
+BaseVersionPtr MinecraftVersionList::getLatestStable() const
+{
+	if(m_lookup.contains(m_latestReleaseID))
+		return m_lookup[m_latestReleaseID];
+	return BaseVersionPtr();
+}
+
+void MinecraftVersionList::updateListData(QList<BaseVersionPtr> versions)
+{
+	beginResetModel();
+	for (auto version : versions)
+	{
+		auto descr = version->descriptor();
+
+		if (!m_lookup.contains(descr))
+		{
+			m_lookup[version->descriptor()] = version;
+			m_vlist.append(version);
+			continue;
+		}
+		auto orig = std::dynamic_pointer_cast<MinecraftVersion>(m_lookup[descr]);
+		auto added = std::dynamic_pointer_cast<MinecraftVersion>(version);
+		// updateListData is called after Mojang list loads. those can be local or remote
+		// remote comes always after local
+		// any other options are ignored
+		if (orig->m_versionSource != Local || added->m_versionSource != Remote)
+		{
+			continue;
+		}
+		// is it actually an update?
+		if (orig->m_updateTime >= added->m_updateTime)
+		{
+			// nope.
+			continue;
+		}
+		// alright, it's an update. put it inside the original, for further processing.
+		orig->upstreamUpdate = added;
+	}
+	sortInternal();
+	endResetModel();
+}
+
+inline QDomElement getDomElementByTagName(QDomElement parent, QString tagname)
+{
+	QDomNodeList elementList = parent.elementsByTagName(tagname);
+	if (elementList.count())
+		return elementList.at(0).toElement();
+	else
+		return QDomElement();
+}
+
+MCVListLoadTask::MCVListLoadTask(MinecraftVersionList *vlist)
+{
+	m_list = vlist;
+	m_currentStable = NULL;
+	vlistReply = nullptr;
+}
+
+void MCVListLoadTask::executeTask()
+{
+	setStatus(tr("Loading instance version list..."));
+	auto worker = MMC->qnam();
+	vlistReply = worker->get(QNetworkRequest(
+		QUrl("http://" + URLConstants::AWS_DOWNLOAD_VERSIONS + "versions.json")));
+	connect(vlistReply, SIGNAL(finished()), this, SLOT(list_downloaded()));
+}
+
+void MCVListLoadTask::list_downloaded()
+{
+	if (vlistReply->error() != QNetworkReply::NoError)
+	{
+		vlistReply->deleteLater();
+		emitFailed("Failed to load Minecraft main version list" + vlistReply->errorString());
+		return;
+	}
+
+	auto data = vlistReply->readAll();
+	vlistReply->deleteLater();
+	try
+	{
+		QJsonParseError jsonError;
+		QJsonDocument jsonDoc = QJsonDocument::fromJson(data, &jsonError);
+		if (jsonError.error != QJsonParseError::NoError)
+		{
+			throw ListLoadError(
+				tr("Error parsing version list JSON: %1").arg(jsonError.errorString()));
+		}
+		m_list->loadMojangList(jsonDoc, Remote);
+	}
+	catch (MMCError &e)
+	{
+		emitFailed(e.cause());
+		return;
+	}
+
+	emitSucceeded();
+	return;
+}
+
+MCVListVersionUpdateTask::MCVListVersionUpdateTask(MinecraftVersionList *vlist,
+												   QString updatedVersion)
+	: Task()
+{
+	m_list = vlist;
+	versionToUpdate = updatedVersion;
+}
+
+void MCVListVersionUpdateTask::executeTask()
+{
+	QString urlstr = "http://" + URLConstants::AWS_DOWNLOAD_VERSIONS + versionToUpdate + "/" +
+					 versionToUpdate + ".json";
+	auto job = new NetJob("Version index");
+	job->addNetAction(ByteArrayDownload::make(QUrl(urlstr)));
+	specificVersionDownloadJob.reset(job);
+	connect(specificVersionDownloadJob.get(), SIGNAL(succeeded()), SLOT(json_downloaded()));
+	connect(specificVersionDownloadJob.get(), SIGNAL(failed(QString)), SIGNAL(failed(QString)));
+	connect(specificVersionDownloadJob.get(), SIGNAL(progress(qint64, qint64)),
+			SIGNAL(progress(qint64, qint64)));
+	specificVersionDownloadJob->start();
+}
+
+void MCVListVersionUpdateTask::json_downloaded()
+{
+	NetActionPtr DlJob = specificVersionDownloadJob->first();
+	auto data = std::dynamic_pointer_cast<ByteArrayDownload>(DlJob)->m_data;
+	specificVersionDownloadJob.reset();
+
+	QJsonParseError jsonError;
+	QJsonDocument jsonDoc = QJsonDocument::fromJson(data, &jsonError);
+
+	if (jsonError.error != QJsonParseError::NoError)
+	{
+		emitFailed(tr("The download version file is not valid."));
+		return;
+	}
+	VersionFilePtr file;
+	try
+	{
+		file = VersionFile::fromJson(jsonDoc, "net.minecraft.json", false);
+	}
+	catch (MMCError &e)
+	{
+		emitFailed(tr("Couldn't process version file: %1").arg(e.cause()));
+		return;
+	}
+	QList<RawLibraryPtr> filteredLibs;
+	QList<RawLibraryPtr> lwjglLibs;
+	QSet<QString> lwjglFilter = {
+		"net.java.jinput:jinput",	 "net.java.jinput:jinput-platform",
+		"net.java.jutils:jutils",	 "org.lwjgl.lwjgl:lwjgl",
+		"org.lwjgl.lwjgl:lwjgl_util", "org.lwjgl.lwjgl:lwjgl-platform"};
+	for (auto lib : file->overwriteLibs)
+	{
+		if (lwjglFilter.contains(lib->fullname()))
+		{
+			lwjglLibs.append(lib);
+		}
+		else
+		{
+			filteredLibs.append(lib);
+		}
+	}
+	file->overwriteLibs = filteredLibs;
+
+	// TODO: recognize and add LWJGL versions here.
+
+	file->fileId = "net.minecraft";
+
+	// now dump the file to disk
+	auto doc = file->toJson(false);
+	auto newdata = doc.toBinaryData();
+	QLOG_INFO() << newdata;
+	QString targetPath = "versions/" + versionToUpdate + "/" + versionToUpdate + ".dat";
+	ensureFilePathExists(targetPath);
+	QSaveFile vfile1(targetPath);
+	if (!vfile1.open(QIODevice::Truncate | QIODevice::WriteOnly))
+	{
+		emitFailed(tr("Can't open %1 for writing.").arg(targetPath));
+		return;
+	}
+	qint64 actual = 0;
+	if ((actual = vfile1.write(newdata)) != newdata.size())
+	{
+		emitFailed(tr("Failed to write into %1. Written %2 out of %3.")
+					   .arg(targetPath)
+					   .arg(actual)
+					   .arg(newdata.size()));
+		return;
+	}
+	if (!vfile1.commit())
+	{
+		emitFailed(tr("Can't commit changes to %1").arg(targetPath));
+		return;
+	}
+
+	m_list->finalizeUpdate(versionToUpdate);
+	emitSucceeded();
+}
+
+std::shared_ptr<Task> MinecraftVersionList::createUpdateTask(QString version)
+{
+	return std::shared_ptr<Task>(new MCVListVersionUpdateTask(this, version));
+}
+
+void MinecraftVersionList::saveCachedList()
+{
+	// FIXME: throw.
+	if (!ensureFilePathExists(localVersionCache))
+		return;
+	QSaveFile tfile(localVersionCache);
+	if (!tfile.open(QIODevice::WriteOnly | QIODevice::Truncate))
+		return;
+	QJsonObject toplevel;
+	QJsonArray entriesArr;
+	for (auto version : m_vlist)
+	{
+		auto mcversion = std::dynamic_pointer_cast<MinecraftVersion>(version);
+		// do not save the remote versions.
+		if (mcversion->m_versionSource != Local)
+			continue;
+		QJsonObject entryObj;
+
+		entryObj.insert("id", mcversion->descriptor());
+		entryObj.insert("time", mcversion->m_updateTimeString);
+		entryObj.insert("releaseTime", mcversion->m_releaseTimeString);
+		entryObj.insert("type", mcversion->m_type);
+		entriesArr.append(entryObj);
+	}
+	toplevel.insert("versions", entriesArr);
+	
+	{
+		bool someLatest = false;
+		QJsonObject latestObj;
+		if(!m_latestReleaseID.isNull())
+		{
+			latestObj.insert("release", m_latestReleaseID);
+			someLatest = true;
+		}
+		if(!m_latestSnapshotID.isNull())
+		{
+			latestObj.insert("snapshot", m_latestSnapshotID);
+			someLatest = true;
+		}
+		if(someLatest)
+		{
+			toplevel.insert("latest", latestObj);
+		}
+	}
+	
+	QJsonDocument doc(toplevel);
+	QByteArray jsonData = doc.toBinaryData();
+	qint64 result = tfile.write(jsonData);
+	if (result == -1)
+		return;
+	if (result != jsonData.size())
+		return;
+	tfile.commit();
+}
+
+void MinecraftVersionList::finalizeUpdate(QString version)
+{
+	int idx = -1;
+	for (int i = 0; i < m_vlist.size(); i++)
+	{
+		if (version == m_vlist[i]->descriptor())
+		{
+			idx = i;
+			break;
+		}
+	}
+	if (idx == -1)
+	{
+		return;
+	}
+
+	auto updatedVersion = std::dynamic_pointer_cast<MinecraftVersion>(m_vlist[idx]);
+
+	if (updatedVersion->m_versionSource == Builtin)
+		return;
+
+	if (updatedVersion->upstreamUpdate)
+	{
+		auto updatedWith = updatedVersion->upstreamUpdate;
+		updatedWith->m_versionSource = Local;
+		m_vlist[idx] = updatedWith;
+		m_lookup[version] = updatedWith;
+	}
+	else
+	{
+		updatedVersion->m_versionSource = Local;
+	}
+
+	dataChanged(index(idx), index(idx));
+
+	saveCachedList();
+}
diff --git a/logic/lists/MinecraftVersionList.h b/logic/minecraft/MinecraftVersionList.h
index 167f4d11..4753ce05 100644
--- a/logic/lists/MinecraftVersionList.h
+++ b/logic/minecraft/MinecraftVersionList.h
@@ -19,11 +19,13 @@
 #include <QList>
 #include <QSet>
 
-#include "BaseVersionList.h"
+#include "logic/BaseVersionList.h"
 #include "logic/tasks/Task.h"
-#include "logic/MinecraftVersion.h"
+#include "logic/minecraft/MinecraftVersion.h"
+#include <logic/net/NetJob.h>
 
 class MCVListLoadTask;
+class MCVListVersionUpdateTask;
 class QNetworkReply;
 
 class MinecraftVersionList : public BaseVersionList
@@ -31,11 +33,19 @@ class MinecraftVersionList : public BaseVersionList
 	Q_OBJECT
 private:
 	void sortInternal();
+	void loadBuiltinList();
+	void loadMojangList(QJsonDocument jsonDoc, VersionSource source);
+	void loadCachedList();
+	void saveCachedList();
+	void finalizeUpdate(QString version);
 public:
 	friend class MCVListLoadTask;
+	friend class MCVListVersionUpdateTask;
 
 	explicit MinecraftVersionList(QObject *parent = 0);
 
+	std::shared_ptr<Task> createUpdateTask(QString version);
+
 	virtual Task *getLoadTask();
 	virtual bool isLoaded();
 	virtual const BaseVersionPtr at(int i) const;
@@ -46,8 +56,12 @@ public:
 
 protected:
 	QList<BaseVersionPtr> m_vlist;
+	QMap<QString, BaseVersionPtr> m_lookup;
 
 	bool m_loaded = false;
+	bool m_hasLocalIndex = false;
+	QString m_latestReleaseID = "INVALID";
+	QString m_latestSnapshotID = "INVALID";
 
 protected
 slots:
@@ -60,9 +74,9 @@ class MCVListLoadTask : public Task
 
 public:
 	explicit MCVListLoadTask(MinecraftVersionList *vlist);
-	~MCVListLoadTask();
+	virtual ~MCVListLoadTask() override{};
 
-	virtual void executeTask();
+	virtual void executeTask() override;
 
 protected
 slots:
@@ -72,5 +86,23 @@ protected:
 	QNetworkReply *vlistReply;
 	MinecraftVersionList *m_list;
 	MinecraftVersion *m_currentStable;
-	QSet<QString> legacyWhitelist;
+};
+
+class MCVListVersionUpdateTask : public Task
+{
+	Q_OBJECT
+
+public:
+	explicit MCVListVersionUpdateTask(MinecraftVersionList *vlist, QString updatedVersion);
+	virtual ~MCVListVersionUpdateTask() override{};
+	virtual void executeTask() override;
+
+protected
+slots:
+	void json_downloaded();
+
+protected:
+	NetJobPtr specificVersionDownloadJob;
+	QString versionToUpdate;
+	MinecraftVersionList *m_list;
 };
diff --git a/logic/OneSixLibrary.cpp b/logic/minecraft/OneSixLibrary.cpp
index 45fa169e..7f69d9f8 100644
--- a/logic/OneSixLibrary.cpp
+++ b/logic/minecraft/OneSixLibrary.cpp
@@ -23,6 +23,23 @@
 #include <JlCompress.h>
 #include "logger/QsLog.h"
 
+OneSixLibrary::OneSixLibrary(RawLibraryPtr base)
+{
+	m_name = base->m_name;
+	m_base_url = base->m_base_url;
+	m_hint = base->m_hint;
+	m_absolute_url = base->m_absolute_url;
+	extract_excludes = base->extract_excludes;
+	m_native_suffixes = base->m_native_suffixes;
+	m_rules = base->m_rules;
+	finalize();
+}
+
+OneSixLibraryPtr OneSixLibrary::fromRawLibrary(RawLibraryPtr lib)
+{
+	return OneSixLibraryPtr(new OneSixLibrary(lib));
+}
+
 void OneSixLibrary::finalize()
 {
 	QStringList parts = m_name.split(':');
@@ -30,7 +47,7 @@ void OneSixLibrary::finalize()
 	relative.replace('.', '/');
 	relative += '/' + parts[1] + '/' + parts[2] + '/' + parts[1] + '-' + parts[2];
 
-	if (!m_is_native)
+	if (!isNative())
 		relative += ".jar";
 	else
 	{
@@ -65,7 +82,7 @@ void OneSixLibrary::finalize()
 		}
 		m_is_active = (result == Allow);
 	}
-	if (m_is_native)
+	if (isNative())
 	{
 		m_is_active = m_is_active && m_native_suffixes.contains(currentSystem);
 		m_decenttype = "Native";
@@ -84,13 +101,8 @@ void OneSixLibrary::setBaseUrl(const QString &base_url)
 {
 	m_base_url = base_url;
 }
-void OneSixLibrary::setIsNative()
-{
-	m_is_native = true;
-}
 void OneSixLibrary::addNative(OpSys os, const QString &suffix)
 {
-	m_is_native = true;
 	m_native_suffixes[os] = suffix;
 }
 void OneSixLibrary::clearSuffixes()
@@ -105,10 +117,6 @@ bool OneSixLibrary::isActive() const
 {
 	return m_is_active;
 }
-bool OneSixLibrary::isNative() const
-{
-	return m_is_native;
-}
 QString OneSixLibrary::downloadUrl() const
 {
 	if (m_absolute_url.size())
@@ -223,52 +231,3 @@ bool OneSixLibrary::extractTo(QString target_dir)
 	}
 	return true;
 }
-
-QJsonObject OneSixLibrary::toJson()
-{
-	QJsonObject libRoot;
-	libRoot.insert("name", m_name);
-	if (m_absolute_url.size())
-		libRoot.insert("MMC-absoluteUrl", m_absolute_url);
-	if (m_hint.size())
-		libRoot.insert("MMC-hint", m_hint);
-	if (m_base_url != "http://" + URLConstants::AWS_DOWNLOAD_LIBRARIES &&
-		m_base_url != "https://" + URLConstants::AWS_DOWNLOAD_LIBRARIES &&
-		m_base_url != "https://" + URLConstants::LIBRARY_BASE && !m_base_url.isEmpty())
-	{
-		libRoot.insert("url", m_base_url);
-	}
-	if (isNative() && m_native_suffixes.size())
-	{
-		QJsonObject nativeList;
-		auto iter = m_native_suffixes.begin();
-		while (iter != m_native_suffixes.end())
-		{
-			nativeList.insert(OpSys_toString(iter.key()), iter.value());
-			iter++;
-		}
-		libRoot.insert("natives", nativeList);
-	}
-	if (isNative() && extract_excludes.size())
-	{
-		QJsonArray excludes;
-		QJsonObject extract;
-		for (auto exclude : extract_excludes)
-		{
-			excludes.append(exclude);
-		}
-		extract.insert("exclude", excludes);
-		libRoot.insert("extract", extract);
-	}
-	if (m_rules.size())
-	{
-		QJsonArray allRules;
-		for (auto &rule : m_rules)
-		{
-			QJsonObject ruleObj = rule->toJson();
-			allRules.append(ruleObj);
-		}
-		libRoot.insert("rules", allRules);
-	}
-	return libRoot;
-}
diff --git a/logic/OneSixLibrary.h b/logic/minecraft/OneSixLibrary.h
index 61d4c8e2..3d38985b 100644
--- a/logic/OneSixLibrary.h
+++ b/logic/minecraft/OneSixLibrary.h
@@ -23,28 +23,17 @@
 #include <memory>
 
 #include "logic/net/URLConstants.h"
-#include "OpSys.h"
+#include "logic/minecraft/OpSys.h"
+#include "logic/minecraft/RawLibrary.h"
 
 class Rule;
 
 class OneSixLibrary;
 typedef std::shared_ptr<OneSixLibrary> OneSixLibraryPtr;
 
-class OneSixLibrary
+class OneSixLibrary : public RawLibrary
 {
 private:
-	// basic values used internally (so far)
-	QString m_name;
-	QString m_base_url = "https://" + URLConstants::LIBRARY_BASE;
-	QList<std::shared_ptr<Rule>> m_rules;
-
-	// custom values
-	/// absolute URL. takes precedence over m_download_path, if defined
-	QString m_absolute_url;
-	/// download hint - how to actually get the library
-	QString m_hint;
-
-	// derived values used for real things
 	/// a decent name fit for display
 	QString m_decentname;
 	/// a decent version fit for display
@@ -57,13 +46,9 @@ private:
 	QString m_download_url;
 	/// is this lib actually active on the current OS?
 	bool m_is_active = false;
-	/// is the library a native?
-	bool m_is_native = false;
-	/// native suffixes per OS
-	QMap<OpSys, QString> m_native_suffixes;
 
 public:
-	QStringList extract_excludes;
+	
 	QString minVersion;
 
 	enum DependType
@@ -80,15 +65,16 @@ public:
 		m_name = name;
 		dependType = type;
 	}
-
+	/// Constructor
+	OneSixLibrary(RawLibraryPtr base);
+	static OneSixLibraryPtr fromRawLibrary(RawLibraryPtr lib);
+	
 	/// Returns the raw name field
 	QString rawName() const
 	{
 		return m_name;
 	}
 
-	QJsonObject toJson();
-
 	/**
 	 * finalize the library, processing the input values into derived values and state
 	 *
@@ -116,8 +102,6 @@ public:
 	/// Set the url base for downloads
 	void setBaseUrl(const QString &base_url);
 
-	/// Call this to mark the library as 'native' (it's a zip archive with DLLs)
-	void setIsNative();
 	/// Attach a name suffix to the specified OS native
 	void addNative(OpSys os, const QString &suffix);
 	/// Clears all suffixes
@@ -127,8 +111,6 @@ public:
 
 	/// Returns true if the library should be loaded (or extracted, in case of natives)
 	bool isActive() const;
-	/// Returns true if the library is native
-	bool isNative() const;
 	/// Get the URL to download the library from
 	QString downloadUrl() const;
 	/// Get the relative path where the library should be saved
diff --git a/logic/OneSixRule.cpp b/logic/minecraft/OneSixRule.cpp
index d8d13b50..93c49e5e 100644
--- a/logic/OneSixRule.cpp
+++ b/logic/minecraft/OneSixRule.cpp
@@ -18,6 +18,15 @@
 
 #include "OneSixRule.h"
 
+RuleAction RuleAction_fromString(QString name)
+{
+	if (name == "allow")
+		return Allow;
+	if (name == "disallow")
+		return Disallow;
+	return Defer;
+}
+
 QList<std::shared_ptr<Rule>> rulesFromJsonV4(const QJsonObject &objectWithRules)
 {
 	QList<std::shared_ptr<Rule>> rules;
@@ -79,11 +88,3 @@ QJsonObject OsRule::toJson()
 	return ruleObj;
 }
 
-RuleAction RuleAction_fromString(QString name)
-{
-	if (name == "allow")
-		return Allow;
-	if (name == "disallow")
-		return Disallow;
-	return Defer;
-}
diff --git a/logic/OneSixRule.h b/logic/minecraft/OneSixRule.h
index 426e2886..a18093b0 100644
--- a/logic/OneSixRule.h
+++ b/logic/minecraft/OneSixRule.h
@@ -16,8 +16,13 @@
 #pragma once
 
 #include <QString>
+#include <QList>
+#include <QJsonObject>
+#include <memory>
+#include "OpSys.h"
 
-#include "logic/OneSixLibrary.h"
+class OneSixLibrary;
+class Rule;
 
 enum RuleAction
 {
@@ -26,7 +31,6 @@ enum RuleAction
 	Defer
 };
 
-RuleAction RuleAction_fromString(QString);
 QList<std::shared_ptr<Rule>> rulesFromJsonV4(const QJsonObject &objectWithRules);
 
 class Rule
diff --git a/logic/OpSys.cpp b/logic/minecraft/OpSys.cpp
index e001b7f3..e001b7f3 100644
--- a/logic/OpSys.cpp
+++ b/logic/minecraft/OpSys.cpp
diff --git a/logic/OpSys.h b/logic/minecraft/OpSys.h
index 363c87d7..363c87d7 100644
--- a/logic/OpSys.h
+++ b/logic/minecraft/OpSys.h
diff --git a/logic/minecraft/ParseUtils.cpp b/logic/minecraft/ParseUtils.cpp
new file mode 100644
index 00000000..f94de6ff
--- /dev/null
+++ b/logic/minecraft/ParseUtils.cpp
@@ -0,0 +1,24 @@
+#include <QDateTime>
+#include <QString>
+#include "ParseUtils.h"
+#include <logic/MMCJson.h>
+
+QDateTime timeFromS3Time(QString str)
+{
+	return QDateTime::fromString(str, Qt::ISODate);
+}
+
+bool parse_timestamp (const QString & raw, QString & save_here, QDateTime & parse_here)
+{
+	save_here = raw;
+	if (save_here.isEmpty())
+	{
+		return false;
+	}
+	parse_here = timeFromS3Time(save_here);
+	if (!parse_here.isValid())
+	{
+		return false;
+	}
+	return true;
+}
diff --git a/logic/minecraft/ParseUtils.h b/logic/minecraft/ParseUtils.h
new file mode 100644
index 00000000..bd2f6ffb
--- /dev/null
+++ b/logic/minecraft/ParseUtils.h
@@ -0,0 +1,14 @@
+#pragma once
+#include <QString>
+#include <QDateTime>
+
+/**
+ * parse the S3 timestamp in 'raw' and fill the forwarded variables.
+ * return true/false for success/failure
+ */
+bool parse_timestamp (const QString &raw, QString &save_here, QDateTime &parse_here);
+
+/**
+ * take the timestamp used by S3 and turn it into QDateTime
+ */
+QDateTime timeFromS3Time(QString str);
diff --git a/logic/minecraft/RawLibrary.cpp b/logic/minecraft/RawLibrary.cpp
new file mode 100644
index 00000000..7e0ebff0
--- /dev/null
+++ b/logic/minecraft/RawLibrary.cpp
@@ -0,0 +1,205 @@
+#include "logic/MMCJson.h"
+using namespace MMCJson;
+
+#include "RawLibrary.h"
+
+RawLibraryPtr RawLibrary::fromJson(const QJsonObject &libObj, const QString &filename)
+{
+	RawLibraryPtr out(new RawLibrary());
+	if (!libObj.contains("name"))
+	{
+		throw JSONValidationError(filename +
+								  "contains a library that doesn't have a 'name' field");
+	}
+	out->m_name = libObj.value("name").toString();
+
+	auto readString = [libObj, filename](const QString & key, QString & variable)
+	{
+		if (libObj.contains(key))
+		{
+			QJsonValue val = libObj.value(key);
+			if (!val.isString())
+			{
+				QLOG_WARN() << key << "is not a string in" << filename << "(skipping)";
+			}
+			else
+			{
+				variable = val.toString();
+			}
+		}
+	};
+
+	readString("url", out->m_base_url);
+	readString("MMC-hint", out->m_hint);
+	readString("MMC-absulute_url", out->m_absolute_url);
+	readString("MMC-absoluteUrl", out->m_absolute_url);
+	if (libObj.contains("extract"))
+	{
+		out->applyExcludes = true;
+		auto extractObj = ensureObject(libObj.value("extract"));
+		for (auto excludeVal : ensureArray(extractObj.value("exclude")))
+		{
+			out->extract_excludes.append(ensureString(excludeVal));
+		}
+	}
+	if (libObj.contains("natives"))
+	{
+		QJsonObject nativesObj = ensureObject(libObj.value("natives"));
+		for (auto it = nativesObj.begin(); it != nativesObj.end(); ++it)
+		{
+			if (!it.value().isString())
+			{
+				QLOG_WARN() << filename << "contains an invalid native (skipping)";
+			}
+			OpSys opSys = OpSys_fromString(it.key());
+			if (opSys != Os_Other)
+			{
+				out->m_native_suffixes[opSys] = it.value().toString();
+			}
+		}
+	}
+	if (libObj.contains("rules"))
+	{
+		out->applyRules = true;
+		out->m_rules = rulesFromJsonV4(libObj);
+	}
+	return out;
+}
+
+RawLibraryPtr RawLibrary::fromJsonPlus(const QJsonObject &libObj, const QString &filename)
+{
+	auto lib = RawLibrary::fromJson(libObj, filename);
+	if (libObj.contains("insert"))
+	{
+		QJsonValue insertVal = ensureExists(libObj.value("insert"), "library insert rule");
+		QString insertString;
+		{
+			if (insertVal.isString())
+			{
+				insertString = insertVal.toString();
+			}
+			else if (insertVal.isObject())
+			{
+				QJsonObject insertObj = insertVal.toObject();
+				if (insertObj.isEmpty())
+				{
+					throw JSONValidationError("One library has an empty insert object in " +
+											  filename);
+				}
+				insertString = insertObj.keys().first();
+				lib->insertData = insertObj.value(insertString).toString();
+			}
+		}
+		if (insertString == "apply")
+		{
+			lib->insertType = RawLibrary::Apply;
+		}
+		else if (insertString == "prepend")
+		{
+			lib->insertType = RawLibrary::Prepend;
+		}
+		else if (insertString == "append")
+		{
+			lib->insertType = RawLibrary::Append;
+		}
+		else if (insertString == "replace")
+		{
+			lib->insertType = RawLibrary::Replace;
+		}
+		else
+		{
+			throw JSONValidationError("A '+' library in " + filename +
+									  " contains an invalid insert type");
+		}
+	}
+	if (libObj.contains("MMC-depend"))
+	{
+		const QString dependString = ensureString(libObj.value("MMC-depend"));
+		if (dependString == "hard")
+		{
+			lib->dependType = RawLibrary::Hard;
+		}
+		else if (dependString == "soft")
+		{
+			lib->dependType = RawLibrary::Soft;
+		}
+		else
+		{
+			throw JSONValidationError("A '+' library in " + filename +
+									  " contains an invalid depend type");
+		}
+	}
+	return lib;
+}
+
+bool RawLibrary::isNative() const
+{
+	return m_native_suffixes.size() != 0;
+}
+
+QJsonObject RawLibrary::toJson()
+{
+	QJsonObject libRoot;
+	libRoot.insert("name", m_name);
+	if (m_absolute_url.size())
+		libRoot.insert("MMC-absoluteUrl", m_absolute_url);
+	if (m_hint.size())
+		libRoot.insert("MMC-hint", m_hint);
+	if (m_base_url != "http://" + URLConstants::AWS_DOWNLOAD_LIBRARIES &&
+		m_base_url != "https://" + URLConstants::AWS_DOWNLOAD_LIBRARIES &&
+		m_base_url != "https://" + URLConstants::LIBRARY_BASE && !m_base_url.isEmpty())
+	{
+		libRoot.insert("url", m_base_url);
+	}
+	if (isNative())
+	{
+		QJsonObject nativeList;
+		auto iter = m_native_suffixes.begin();
+		while (iter != m_native_suffixes.end())
+		{
+			nativeList.insert(OpSys_toString(iter.key()), iter.value());
+			iter++;
+		}
+		libRoot.insert("natives", nativeList);
+		if (extract_excludes.size())
+		{
+			QJsonArray excludes;
+			QJsonObject extract;
+			for (auto exclude : extract_excludes)
+			{
+				excludes.append(exclude);
+			}
+			extract.insert("exclude", excludes);
+			libRoot.insert("extract", extract);
+		}
+	}
+	if (m_rules.size())
+	{
+		QJsonArray allRules;
+		for (auto &rule : m_rules)
+		{
+			QJsonObject ruleObj = rule->toJson();
+			allRules.append(ruleObj);
+		}
+		libRoot.insert("rules", allRules);
+	}
+	return libRoot;
+}
+
+QString RawLibrary::fullname()
+{
+	QStringList parts = m_name.split(':');
+	return parts[0] + ":" + parts[1];
+}
+
+QString RawLibrary::group()
+{
+	QStringList parts = m_name.split(':');
+	return parts[0];
+}
+
+QString RawLibrary::version()
+{
+	QStringList parts = m_name.split(':');
+	return parts[2];
+}
diff --git a/logic/minecraft/RawLibrary.h b/logic/minecraft/RawLibrary.h
new file mode 100644
index 00000000..f5a28c61
--- /dev/null
+++ b/logic/minecraft/RawLibrary.h
@@ -0,0 +1,64 @@
+#pragma once
+#include <QString>
+#include <QPair>
+#include <QList>
+#include <QStringList>
+#include <QMap>
+#include <memory>
+
+#include "logic/minecraft/OneSixRule.h"
+#include "logic/minecraft/OpSys.h"
+#include "logic/net/URLConstants.h"
+
+class RawLibrary;
+typedef std::shared_ptr<RawLibrary> RawLibraryPtr;
+
+class RawLibrary
+{
+public: /* methods */
+	/// read and create a basic library
+	static RawLibraryPtr fromJson(const QJsonObject &libObj, const QString &filename);
+	/// read and create a MultiMC '+' library. Those have some extra fields.
+	static RawLibraryPtr fromJsonPlus(const QJsonObject &libObj, const QString &filename);
+	QJsonObject toJson();
+	
+	QString fullname();
+	QString version();
+	QString group();
+	
+public: /* data */
+	QString m_name;
+	QString m_base_url = "https://" + URLConstants::LIBRARY_BASE;
+	/// type hint - modifies how the library is treated
+	QString m_hint;
+	/// absolute URL. takes precedence over m_download_path, if defined
+	QString m_absolute_url;
+
+	bool applyExcludes = false;
+	QStringList extract_excludes;
+
+	/// Returns true if the library is native
+	bool isNative() const;
+	/// native suffixes per OS
+	QMap<OpSys, QString> m_native_suffixes;
+
+	bool applyRules = false;
+	QList<std::shared_ptr<Rule>> m_rules;
+
+	// used for '+' libraries
+	enum InsertType
+	{
+		Apply,
+		Append,
+		Prepend,
+		Replace
+	} insertType = Append;
+	QString insertData;
+	
+	// soft or hard dependency? hard means 'needs equal', soft means 'needs equal or newer'
+	enum DependType
+	{
+		Soft,
+		Hard
+	} dependType = Soft;
+};
diff --git a/logic/minecraft/VersionBuildError.h b/logic/minecraft/VersionBuildError.h
new file mode 100644
index 00000000..ae479851
--- /dev/null
+++ b/logic/minecraft/VersionBuildError.h
@@ -0,0 +1,58 @@
+#include "MMCError.h"
+
+class VersionBuildError : public MMCError
+{
+public:
+	VersionBuildError(QString cause) : MMCError(cause) {};
+	virtual ~VersionBuildError() noexcept
+	{
+	}
+};
+
+/**
+ * the base version file was meant for a newer version of the vanilla launcher than we support
+ */
+class LauncherVersionError : public VersionBuildError
+{
+public:
+	LauncherVersionError(int actual, int supported)
+		: VersionBuildError(QObject::tr(
+			  "The base version file of this instance was meant for a newer (%1) "
+			  "version of the vanilla launcher than this version of MultiMC supports (%2).")
+								.arg(actual)
+								.arg(supported)) {};
+	virtual ~LauncherVersionError() noexcept
+	{
+	}
+};
+
+/**
+ * some patch was intended for a different version of minecraft
+ */
+class MinecraftVersionMismatch : public VersionBuildError
+{
+public:
+	MinecraftVersionMismatch(QString fileId, QString mcVersion, QString parentMcVersion)
+		: VersionBuildError(QObject::tr("The patch %1 is for a different version of Minecraft "
+										"(%2) than that of the instance (%3).")
+								.arg(fileId)
+								.arg(mcVersion)
+								.arg(parentMcVersion)) {};
+	virtual ~MinecraftVersionMismatch() noexcept
+	{
+	}
+};
+
+/**
+ * files required for the version are not (yet?) present
+ */
+class VersionIncomplete : public VersionBuildError
+{
+public:
+	VersionIncomplete(QString missingPatch)
+		: VersionBuildError(QObject::tr("Version is incomplete: missing %1.")
+								.arg(missingPatch)) {};
+	virtual ~VersionIncomplete() noexcept
+	{
+	}
+};
\ No newline at end of file
diff --git a/logic/minecraft/VersionBuilder.cpp b/logic/minecraft/VersionBuilder.cpp
new file mode 100644
index 00000000..ddcf6333
--- /dev/null
+++ b/logic/minecraft/VersionBuilder.cpp
@@ -0,0 +1,349 @@
+/* Copyright 2013 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <QList>
+#include <QJsonObject>
+#include <QJsonArray>
+#include <QJsonDocument>
+#include <QFile>
+#include <QFileInfo>
+#include <QMessageBox>
+#include <QObject>
+#include <QDir>
+#include <QDebug>
+#include <qresource.h>
+#include <modutils.h>
+
+#include "MultiMC.h"
+#include "logic/minecraft/VersionBuilder.h"
+#include "logic/minecraft/InstanceVersion.h"
+#include "logic/minecraft/OneSixRule.h"
+#include "logic/minecraft/VersionPatch.h"
+#include "logic/minecraft/VersionFile.h"
+#include "VersionBuildError.h"
+#include "MinecraftVersionList.h"
+
+#include "logic/OneSixInstance.h"
+#include "logic/MMCJson.h"
+
+#include "logger/QsLog.h"
+
+VersionBuilder::VersionBuilder()
+{
+}
+
+void VersionBuilder::build(InstanceVersion *version, OneSixInstance *instance,
+						   const QStringList &external)
+{
+	VersionBuilder builder;
+	builder.m_version = version;
+	builder.m_instance = instance;
+	builder.external_patches = external;
+	builder.buildInternal();
+}
+
+void VersionBuilder::readJsonAndApplyToVersion(InstanceVersion *version, const QJsonObject &obj)
+{
+	VersionBuilder builder;
+	builder.m_version = version;
+	builder.m_instance = 0;
+	builder.readJsonAndApply(obj);
+}
+
+void VersionBuilder::buildFromCustomJson()
+{
+	QLOG_INFO() << "Building version from custom.json within the instance.";
+	QLOG_INFO() << "Reading custom.json";
+	auto file = parseJsonFile(QFileInfo(instance_root.absoluteFilePath("custom.json")), false);
+	file->name = "custom.json";
+	file->filename = "custom.json";
+	file->fileId = "org.multimc.custom.json";
+	file->order = -1;
+	file->version = QString();
+	m_version->VersionPatches.append(file);
+	m_version->finalize();
+	return;
+}
+
+void VersionBuilder::buildFromVersionJson()
+{
+	QLOG_INFO() << "Building version from version.json and patches within the instance.";
+	QLOG_INFO() << "Reading version.json";
+	auto file = parseJsonFile(QFileInfo(instance_root.absoluteFilePath("version.json")), false);
+	file->name = "Minecraft";
+	file->fileId = "org.multimc.version.json";
+	file->order = -1;
+	file->version = m_instance->intendedVersionId();
+	file->mcVersion = m_instance->intendedVersionId();
+	m_version->VersionPatches.append(file);
+
+	// load all patches, put into map for ordering, apply in the right order
+	readInstancePatches();
+
+	// some final touches
+	m_version->finalize();
+}
+
+void VersionBuilder::readInstancePatches()
+{
+	PatchOrder userOrder;
+	readOverrideOrders(m_instance, userOrder);
+	QDir patches(instance_root.absoluteFilePath("patches/"));
+
+	// first, load things by sort order.
+	for (auto id : userOrder)
+	{
+		// ignore builtins
+		if (id == "net.minecraft")
+			continue;
+		if (id == "org.lwjgl")
+			continue;
+		// parse the file
+		QString filename = patches.absoluteFilePath(id + ".json");
+		QLOG_INFO() << "Reading" << filename << "by user order";
+		auto file = parseJsonFile(QFileInfo(filename), false);
+		// sanity check. prevent tampering with files.
+		if (file->fileId != id)
+		{
+			throw VersionBuildError(
+				QObject::tr("load id %1 does not match internal id %2").arg(id, file->fileId));
+		}
+		m_version->VersionPatches.append(file);
+	}
+	// now load the rest by internal preference.
+	QMap<int, QPair<QString, VersionFilePtr>> files;
+	for (auto info : patches.entryInfoList(QStringList() << "*.json", QDir::Files))
+	{
+		// parse the file
+		QLOG_INFO() << "Reading" << info.fileName();
+		auto file = parseJsonFile(info, true);
+		// ignore builtins
+		if (file->fileId == "net.minecraft")
+			continue;
+		if (file->fileId == "org.lwjgl")
+			continue;
+		// do not load what we already loaded in the first pass
+		if (userOrder.contains(file->fileId))
+			continue;
+		if (files.contains(file->order))
+		{
+			// FIXME: do not throw?
+			throw VersionBuildError(QObject::tr("%1 has the same order as %2")
+										.arg(file->fileId, files[file->order].second->fileId));
+		}
+		files.insert(file->order, qMakePair(info.fileName(), file));
+	}
+	for (auto order : files.keys())
+	{
+		auto &filePair = files[order];
+		m_version->VersionPatches.append(filePair.second);
+	}
+}
+
+void VersionBuilder::buildFromExternalPatches()
+{
+	QLOG_INFO() << "Building version from external files.";
+	int externalOrder = -1;
+	for (auto fileName : external_patches)
+	{
+		QLOG_INFO() << "Reading" << fileName;
+		auto file = parseJsonFile(QFileInfo(fileName), false, fileName.endsWith("pack.json"));
+		file->name = QFileInfo(fileName).fileName();
+		file->fileId = "org.multimc.external." + file->name;
+		file->order = (externalOrder += 1);
+		file->version = QString();
+		file->mcVersion = QString();
+		m_version->VersionPatches.append(file);
+	}
+	// some final touches
+	m_version->finalize();
+}
+
+void VersionBuilder::buildFromMultilayer()
+{
+	QLOG_INFO() << "Building version from multilayered sources.";
+	// just the builtin stuff for now
+	auto minecraftList = MMC->minecraftlist();
+	auto mcversion = minecraftList->findVersion(m_instance->intendedVersionId());
+	auto minecraftPatch = std::dynamic_pointer_cast<VersionPatch>(mcversion);
+	if (!minecraftPatch)
+	{
+		throw VersionIncomplete("net.minecraft");
+	}
+	minecraftPatch->setOrder(-2);
+	m_version->VersionPatches.append(minecraftPatch);
+
+	// TODO: this is obviously fake.
+	QResource LWJGL(":/versions/LWJGL/2.9.1.json");
+	auto lwjgl = parseJsonFile(LWJGL.absoluteFilePath(), false, false);
+	auto lwjglPatch = std::dynamic_pointer_cast<VersionPatch>(lwjgl);
+	if (!lwjglPatch)
+	{
+		throw VersionIncomplete("org.lwjgl");
+	}
+	lwjglPatch->setOrder(-1);
+	m_version->VersionPatches.append(lwjglPatch);
+
+	// load all patches, put into map for ordering, apply in the right order
+	readInstancePatches();
+
+	m_version->finalize();
+}
+
+void VersionBuilder::buildInternal()
+{
+	m_version->VersionPatches.clear();
+	instance_root = QDir(m_instance->instanceRoot());
+	// if we do external files, do just those.
+	if (!external_patches.isEmpty())
+	{
+		buildFromExternalPatches();
+	}
+	// else, if there's custom json, we just do that.
+	else if (QFile::exists(instance_root.absoluteFilePath("custom.json")))
+	{
+		buildFromCustomJson();
+	}
+	// version.json -> patches/*.json
+	else if (QFile::exists(instance_root.absoluteFilePath("version.json")))
+	{
+		buildFromVersionJson();
+	}
+	else
+	{
+		buildFromMultilayer();
+	}
+}
+
+void VersionBuilder::readJsonAndApply(const QJsonObject &obj)
+{
+	m_version->clear();
+
+	auto file = VersionFile::fromJson(QJsonDocument(obj), QString(), false);
+
+	file->applyTo(m_version);
+	m_version->VersionPatches.append(file);
+}
+
+VersionFilePtr VersionBuilder::parseJsonFile(const QFileInfo &fileInfo, const bool requireOrder,
+											 bool isFTB)
+{
+	QFile file(fileInfo.absoluteFilePath());
+	if (!file.open(QFile::ReadOnly))
+	{
+		throw JSONValidationError(QObject::tr("Unable to open the version file %1: %2.")
+									  .arg(fileInfo.fileName(), file.errorString()));
+	}
+	QJsonParseError error;
+	QJsonDocument doc = QJsonDocument::fromJson(file.readAll(), &error);
+	if (error.error != QJsonParseError::NoError)
+	{
+		throw JSONValidationError(
+			QObject::tr("Unable to process the version file %1: %2 at %3.")
+				.arg(fileInfo.fileName(), error.errorString())
+				.arg(error.offset));
+	}
+	return VersionFile::fromJson(doc, file.fileName(), requireOrder, isFTB);
+}
+
+VersionFilePtr VersionBuilder::parseBinaryJsonFile(const QFileInfo &fileInfo)
+{
+	QFile file(fileInfo.absoluteFilePath());
+	if (!file.open(QFile::ReadOnly))
+	{
+		throw JSONValidationError(QObject::tr("Unable to open the version file %1: %2.")
+									  .arg(fileInfo.fileName(), file.errorString()));
+	}
+	QJsonDocument doc = QJsonDocument::fromBinaryData(file.readAll());
+	file.close();
+	if (doc.isNull())
+	{
+		file.remove();
+		throw JSONValidationError(
+			QObject::tr("Unable to process the version file %1.").arg(fileInfo.fileName()));
+	}
+	return VersionFile::fromJson(doc, file.fileName(), false, false);
+}
+
+static const int currentOrderFileVersion = 1;
+
+bool VersionBuilder::readOverrideOrders(OneSixInstance *instance, PatchOrder &order)
+{
+	QFile orderFile(instance->instanceRoot() + "/order.json");
+	if (!orderFile.open(QFile::ReadOnly))
+	{
+		QLOG_ERROR() << "Couldn't open" << orderFile.fileName()
+					 << " for reading:" << orderFile.errorString();
+		QLOG_WARN() << "Ignoring overriden order";
+		return false;
+	}
+
+	// and it's valid JSON
+	QJsonParseError error;
+	QJsonDocument doc = QJsonDocument::fromJson(orderFile.readAll(), &error);
+	if (error.error != QJsonParseError::NoError)
+	{
+		QLOG_ERROR() << "Couldn't parse" << orderFile.fileName() << ":" << error.errorString();
+		QLOG_WARN() << "Ignoring overriden order";
+		return false;
+	}
+
+	// and then read it and process it if all above is true.
+	try
+	{
+		auto obj = MMCJson::ensureObject(doc);
+		// check order file version.
+		auto version = MMCJson::ensureInteger(obj.value("version"), "version");
+		if (version != currentOrderFileVersion)
+		{
+			throw JSONValidationError(QObject::tr("Invalid order file version, expected %1")
+										  .arg(currentOrderFileVersion));
+		}
+		auto orderArray = MMCJson::ensureArray(obj.value("order"));
+		for(auto item: orderArray)
+		{
+			order.append(MMCJson::ensureString(item));
+		}
+	}
+	catch (JSONValidationError &err)
+	{
+		QLOG_ERROR() << "Couldn't parse" << orderFile.fileName() << ": bad file format";
+		QLOG_WARN() << "Ignoring overriden order";
+		order.clear();
+		return false;
+	}
+	return true;
+}
+
+bool VersionBuilder::writeOverrideOrders(OneSixInstance *instance, const PatchOrder &order)
+{
+	QJsonObject obj;
+	obj.insert("version", currentOrderFileVersion);
+	QJsonArray orderArray;
+	for(auto str: order)
+	{
+		orderArray.append(str);
+	}
+	obj.insert("order", orderArray);
+	QFile orderFile(instance->instanceRoot() + "/order.json");
+	if (!orderFile.open(QFile::WriteOnly))
+	{
+		QLOG_ERROR() << "Couldn't open" << orderFile.fileName()
+					 << "for writing:" << orderFile.errorString();
+		return false;
+	}
+	orderFile.write(QJsonDocument(obj).toJson(QJsonDocument::Indented));
+	return true;
+}
diff --git a/logic/minecraft/VersionBuilder.h b/logic/minecraft/VersionBuilder.h
new file mode 100644
index 00000000..350179b9
--- /dev/null
+++ b/logic/minecraft/VersionBuilder.h
@@ -0,0 +1,56 @@
+/* Copyright 2013 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <QString>
+#include <QMap>
+#include "VersionFile.h"
+
+class InstanceVersion;
+class OneSixInstance;
+class QJsonObject;
+class QFileInfo;
+
+typedef QStringList PatchOrder;
+
+class VersionBuilder
+{
+	VersionBuilder();
+public:
+	static void build(InstanceVersion *version, OneSixInstance *instance, const QStringList &external);
+	static void readJsonAndApplyToVersion(InstanceVersion *version, const QJsonObject &obj);
+	static VersionFilePtr parseJsonFile(const QFileInfo &fileInfo, const bool requireOrder, bool isFTB = false);
+	static VersionFilePtr parseBinaryJsonFile(const QFileInfo &fileInfo);
+	
+	bool readOverrideOrders(OneSixInstance *instance, PatchOrder &order);
+	static bool writeOverrideOrders(OneSixInstance *instance, const PatchOrder &order);
+
+private:
+	InstanceVersion *m_version;
+	OneSixInstance *m_instance;
+	QStringList external_patches;
+	QDir instance_root;
+	
+	void buildInternal();
+	void buildFromExternalPatches();
+	void buildFromCustomJson();
+	void buildFromVersionJson();
+	void buildFromMultilayer();
+	
+	void readInstancePatches();
+	
+	void readJsonAndApply(const QJsonObject &obj);
+};
diff --git a/logic/VersionFile.cpp b/logic/minecraft/VersionFile.cpp
index cd2a4f9c..93f57116 100644
--- a/logic/VersionFile.cpp
+++ b/logic/minecraft/VersionFile.cpp
@@ -1,84 +1,41 @@
 #include <QJsonArray>
 #include <QJsonDocument>
-
 #include <modutils.h>
 
 #include "logger/QsLog.h"
-#include "logic/VersionFile.h"
-#include "logic/OneSixLibrary.h"
-#include "logic/VersionFinal.h"
-#include "MMCJson.h"
 
+#include "logic/minecraft/VersionFile.h"
+#include "logic/minecraft/OneSixLibrary.h"
+#include "logic/minecraft/InstanceVersion.h"
+#include "logic/minecraft/JarMod.h"
+#include "ParseUtils.h"
+
+#include "logic/MMCJson.h"
 using namespace MMCJson;
 
+#include "VersionBuildError.h"
+
 #define CURRENT_MINIMUM_LAUNCHER_VERSION 14
 
-RawLibraryPtr RawLibrary::fromJson(const QJsonObject &libObj, const QString &filename)
+int findLibrary(QList<OneSixLibraryPtr> haystack, const QString &needle)
 {
-	RawLibraryPtr out(new RawLibrary());
-	if (!libObj.contains("name"))
-	{
-		throw JSONValidationError(filename +
-								  "contains a library that doesn't have a 'name' field");
-	}
-	out->name = libObj.value("name").toString();
-
-	auto readString = [libObj, filename](const QString & key, QString & variable)
-	{
-		if (libObj.contains(key))
-		{
-			QJsonValue val = libObj.value(key);
-			if (!val.isString())
-			{
-				QLOG_WARN() << key << "is not a string in" << filename << "(skipping)";
-			}
-			else
-			{
-				variable = val.toString();
-			}
-		}
-	};
-
-	readString("url", out->url);
-	readString("MMC-hint", out->hint);
-	readString("MMC-absulute_url", out->absoluteUrl);
-	readString("MMC-absoluteUrl", out->absoluteUrl);
-	if (libObj.contains("extract"))
-	{
-		out->applyExcludes = true;
-		auto extractObj = ensureObject(libObj.value("extract"));
-		for (auto excludeVal : ensureArray(extractObj.value("exclude")))
-		{
-			out->excludes.append(ensureString(excludeVal));
-		}
-	}
-	if (libObj.contains("natives"))
+	int retval = -1;
+	for (int i = 0; i < haystack.size(); ++i)
 	{
-		out->applyNatives = true;
-		QJsonObject nativesObj = ensureObject(libObj.value("natives"));
-		for (auto it = nativesObj.begin(); it != nativesObj.end(); ++it)
+		QString chunk = haystack.at(i)->rawName();
+		if (QRegExp(needle, Qt::CaseSensitive, QRegExp::WildcardUnix).indexIn(chunk) != -1)
 		{
-			if (!it.value().isString())
-			{
-				QLOG_WARN() << filename << "contains an invalid native (skipping)";
-			}
-			OpSys opSys = OpSys_fromString(it.key());
-			if (opSys != Os_Other)
-			{
-				out->natives.append(qMakePair(opSys, it.value().toString()));
-			}
+			// only one is allowed.
+			if (retval != -1)
+				return -1;
+			retval = i;
 		}
 	}
-	if (libObj.contains("rules"))
-	{
-		out->applyRules = true;
-		out->rules = rulesFromJsonV4(libObj);
-	}
-	return out;
+	return retval;
 }
 
 VersionFilePtr VersionFile::fromJson(const QJsonDocument &doc, const QString &filename,
-								  const bool requireOrder, const bool isFTB)
+									 const bool requireOrder, const bool isFTB)
 {
 	VersionFilePtr out(new VersionFile());
 	if (doc.isEmpty() || doc.isNull())
@@ -87,7 +44,6 @@ VersionFilePtr VersionFile::fromJson(const QJsonDocument &doc, const QString &fi
 	}
 	if (!doc.isObject())
 	{
-		throw JSONValidationError("The root of " + filename + " is not an object");
 	}
 
 	QJsonObject root = doc.object();
@@ -111,7 +67,7 @@ VersionFilePtr VersionFile::fromJson(const QJsonDocument &doc, const QString &fi
 	out->mcVersion = root.value("mcVersion").toString();
 	out->filename = filename;
 
-	auto readString = [root, filename](const QString & key, QString & variable)
+	auto readString = [root](const QString & key, QString & variable)
 	{
 		if (root.contains(key))
 		{
@@ -119,6 +75,16 @@ VersionFilePtr VersionFile::fromJson(const QJsonDocument &doc, const QString &fi
 		}
 	};
 
+	auto readStringRet = [root](const QString & key)->QString
+	{
+		if (root.contains(key))
+		{
+			return ensureString(root.value(key));
+		}
+		return QString();
+	}
+	;
+
 	// FIXME: This should be ignored when applying.
 	if (!isFTB)
 	{
@@ -126,13 +92,16 @@ VersionFilePtr VersionFile::fromJson(const QJsonDocument &doc, const QString &fi
 	}
 
 	readString("mainClass", out->mainClass);
+	readString("appletClass", out->appletClass);
 	readString("processArguments", out->processArguments);
 	readString("minecraftArguments", out->overwriteMinecraftArguments);
 	readString("+minecraftArguments", out->addMinecraftArguments);
 	readString("-minecraftArguments", out->removeMinecraftArguments);
 	readString("type", out->type);
-	readString("releaseTime", out->releaseTime);
-	readString("time", out->time);
+
+	parse_timestamp(readStringRet("releaseTime"), out->m_releaseTimeString, out->m_releaseTime);
+	parse_timestamp(readStringRet("time"), out->m_updateTimeString, out->m_updateTime);
+
 	readString("assets", out->assets);
 
 	if (root.contains("minimumLauncherVersion"))
@@ -165,6 +134,14 @@ VersionFilePtr VersionFile::fromJson(const QJsonDocument &doc, const QString &fi
 		}
 	}
 
+	if (root.contains("+traits"))
+	{
+		for (auto tweakerVal : ensureArray(root.value("+traits")))
+		{
+			out->traits.insert(ensureString(tweakerVal));
+		}
+	}
+
 	if (root.contains("libraries"))
 	{
 		// FIXME: This should be done when applying.
@@ -177,7 +154,7 @@ VersionFilePtr VersionFile::fromJson(const QJsonDocument &doc, const QString &fi
 			// FIXME: This should be done when applying.
 			if (isFTB)
 			{
-				lib->hint = "local";
+				lib->m_hint = "local";
 				lib->insertType = RawLibrary::Prepend;
 				out->addLibs.prepend(lib);
 			}
@@ -188,76 +165,29 @@ VersionFilePtr VersionFile::fromJson(const QJsonDocument &doc, const QString &fi
 		}
 	}
 
+	if (root.contains("+jarMods"))
+	{
+		for (auto libVal : ensureArray(root.value("+jarMods")))
+		{
+			QJsonObject libObj = ensureObject(libVal);
+			// parse the jarmod
+			auto lib = Jarmod::fromJson(libObj, filename);
+			// and add to jar mods
+			out->jarMods.append(lib);
+		}
+	}
+
 	if (root.contains("+libraries"))
 	{
 		for (auto libVal : ensureArray(root.value("+libraries")))
 		{
 			QJsonObject libObj = ensureObject(libVal);
-			QJsonValue insertVal = ensureExists(libObj.value("insert"));
-
 			// parse the library
-			auto lib = RawLibrary::fromJson(libObj, filename);
-
-			// TODO: utility functions for handling this case. templates?
-			QString insertString;
-			{
-				if (insertVal.isString())
-				{
-					insertString = insertVal.toString();
-				}
-				else if (insertVal.isObject())
-				{
-					QJsonObject insertObj = insertVal.toObject();
-					if (insertObj.isEmpty())
-					{
-						throw JSONValidationError("One library has an empty insert object in " +
-												  filename);
-					}
-					insertString = insertObj.keys().first();
-					lib->insertData = insertObj.value(insertString).toString();
-				}
-			}
-			if (insertString == "apply")
-			{
-				lib->insertType = RawLibrary::Apply;
-			}
-			else if (insertString == "prepend")
-			{
-				lib->insertType = RawLibrary::Prepend;
-			}
-			else if (insertString == "append")
-			{
-				lib->insertType = RawLibrary::Prepend;
-			}
-			else if (insertString == "replace")
-			{
-				lib->insertType = RawLibrary::Replace;
-			}
-			else
-			{
-				throw JSONValidationError("A '+' library in " + filename +
-										  " contains an invalid insert type");
-			}
-			if (libObj.contains("MMC-depend"))
-			{
-				const QString dependString = ensureString(libObj.value("MMC-depend"));
-				if (dependString == "hard")
-				{
-					lib->dependType = RawLibrary::Hard;
-				}
-				else if (dependString == "soft")
-				{
-					lib->dependType = RawLibrary::Soft;
-				}
-				else
-				{
-					throw JSONValidationError("A '+' library in " + filename +
-											  " contains an invalid depend type");
-				}
-			}
+			auto lib = RawLibrary::fromJsonPlus(libObj, filename);
 			out->addLibs.append(lib);
 		}
 	}
+
 	if (root.contains("-libraries"))
 	{
 		for (auto libVal : ensureArray(root.value("-libraries")))
@@ -269,53 +199,81 @@ VersionFilePtr VersionFile::fromJson(const QJsonDocument &doc, const QString &fi
 	return out;
 }
 
-OneSixLibraryPtr VersionFile::createLibrary(RawLibraryPtr lib)
+QJsonDocument VersionFile::toJson(bool saveOrder)
 {
-	std::shared_ptr<OneSixLibrary> out(new OneSixLibrary(lib->name));
-	if (!lib->url.isEmpty())
+	QJsonObject root;
+	if (saveOrder)
+	{
+		root.insert("order", order);
+	}
+	writeString(root, "name", name);
+	writeString(root, "fileId", fileId);
+	writeString(root, "version", version);
+	writeString(root, "mcVersion", mcVersion);
+	writeString(root, "id", id);
+	writeString(root, "mainClass", mainClass);
+	writeString(root, "appletClass", appletClass);
+	writeString(root, "processArguments", processArguments);
+	writeString(root, "minecraftArguments", overwriteMinecraftArguments);
+	writeString(root, "+minecraftArguments", addMinecraftArguments);
+	writeString(root, "-minecraftArguments", removeMinecraftArguments);
+	writeString(root, "type", type);
+	writeString(root, "assets", assets);
+	if (isMinecraftVersion())
+	{
+		writeString(root, "releaseTime", m_releaseTimeString);
+		writeString(root, "time", m_updateTimeString);
+	}
+	if (minimumLauncherVersion != -1)
 	{
-		out->setBaseUrl(lib->url);
+		root.insert("minimumLauncherVersion", minimumLauncherVersion);
 	}
-	out->setHint(lib->hint);
-	if (!lib->absoluteUrl.isEmpty())
+	writeStringList(root, "tweakers", overwriteTweakers);
+	writeStringList(root, "+tweakers", addTweakers);
+	writeStringList(root, "-tweakers", removeTweakers);
+	writeStringList(root, "+traits", traits.toList());
+	writeObjectList(root, "libraries", overwriteLibs);
+	writeObjectList(root, "+libraries", addLibs);
+	writeObjectList(root, "+jarMods", jarMods);
+	// FIXME: removed libs are special snowflakes.
+	if (removeLibs.size())
 	{
-		out->setAbsoluteUrl(lib->absoluteUrl);
+		QJsonArray array;
+		for (auto lib : removeLibs)
+		{
+			QJsonObject rmlibobj;
+			rmlibobj.insert("name", lib);
+			array.append(rmlibobj);
+		}
+		root.insert("-libraries", array);
 	}
-	out->setAbsoluteUrl(lib->absoluteUrl);
-	out->extract_excludes = lib->excludes;
-	for (auto native : lib->natives)
+	// write the contents to a json document.
 	{
-		out->addNative(native.first, native.second);
+		QJsonDocument out;
+		out.setObject(root);
+		return out;
 	}
-	out->setRules(lib->rules);
-	out->finalize();
-	return out;
 }
 
-int VersionFile::findLibrary(QList<OneSixLibraryPtr> haystack, const QString &needle)
+bool VersionFile::isMinecraftVersion()
 {
-	int retval = -1;
-	for (int i = 0; i < haystack.size(); ++i)
-	{
-		QString chunk = haystack.at(i)->rawName();
-		if (QRegExp(needle, Qt::CaseSensitive, QRegExp::WildcardUnix).indexIn(chunk) != -1)
-		{
-			// only one is allowed.
-			if(retval != -1)
-				return -1;
-			retval = i;
-		}
-	}
-	return retval;
+	return (fileId == "org.multimc.version.json") || (fileId == "net.minecraft") ||
+		   (fileId == "org.multimc.custom.json");
+}
+
+bool VersionFile::hasJarMods()
+{
+	return !jarMods.isEmpty();
 }
 
-void VersionFile::applyTo(VersionFinal *version)
+void VersionFile::applyTo(InstanceVersion *version)
 {
 	if (minimumLauncherVersion != -1)
 	{
 		if (minimumLauncherVersion > CURRENT_MINIMUM_LAUNCHER_VERSION)
 		{
-			throw LauncherVersionError(minimumLauncherVersion, CURRENT_MINIMUM_LAUNCHER_VERSION);
+			throw LauncherVersionError(minimumLauncherVersion,
+									   CURRENT_MINIMUM_LAUNCHER_VERSION);
 		}
 	}
 
@@ -336,21 +294,34 @@ void VersionFile::applyTo(VersionFinal *version)
 	{
 		version->mainClass = mainClass;
 	}
-	if (!processArguments.isNull())
+	if (!appletClass.isNull())
 	{
-		version->processArguments = processArguments;
+		version->appletClass = appletClass;
 	}
-	if (!type.isNull())
-	{
-		version->type = type;
-	}
-	if (!releaseTime.isNull())
+	if (!processArguments.isNull())
 	{
-		version->releaseTime = releaseTime;
+		if (isMinecraftVersion())
+		{
+			version->vanillaProcessArguments = processArguments;
+		}
+		version->processArguments = processArguments;
 	}
-	if (!time.isNull())
+	if (isMinecraftVersion())
 	{
-		version->time = time;
+		if (!type.isNull())
+		{
+			version->type = type;
+		}
+		if (!m_releaseTimeString.isNull())
+		{
+			version->m_releaseTimeString = m_releaseTimeString;
+			version->m_releaseTime = m_releaseTime;
+		}
+		if (!m_updateTimeString.isNull())
+		{
+			version->m_updateTimeString = m_updateTimeString;
+			version->m_updateTime = m_updateTime;
+		}
 	}
 	if (!assets.isNull())
 	{
@@ -358,10 +329,15 @@ void VersionFile::applyTo(VersionFinal *version)
 	}
 	if (minimumLauncherVersion >= 0)
 	{
-		version->minimumLauncherVersion = minimumLauncherVersion;
+		if (version->minimumLauncherVersion < minimumLauncherVersion)
+			version->minimumLauncherVersion = minimumLauncherVersion;
 	}
 	if (!overwriteMinecraftArguments.isNull())
 	{
+		if (isMinecraftVersion())
+		{
+			version->vanillaMinecraftArguments = overwriteMinecraftArguments;
+		}
 		version->minecraftArguments = overwriteMinecraftArguments;
 	}
 	if (!addMinecraftArguments.isNull())
@@ -384,13 +360,20 @@ void VersionFile::applyTo(VersionFinal *version)
 	{
 		version->tweakers.removeAll(tweaker);
 	}
+	version->jarMods.append(jarMods);
+	version->traits.unite(traits);
 	if (shouldOverwriteLibs)
 	{
-		version->libraries.clear();
+		QList<OneSixLibraryPtr> libs;
 		for (auto lib : overwriteLibs)
 		{
-			version->libraries.append(createLibrary(lib));
+			libs.append(OneSixLibrary::fromRawLibrary(lib));
+		}
+		if (isMinecraftVersion())
+		{
+			version->vanillaLibraries = libs;
 		}
+		version->libraries = libs;
 	}
 	for (auto lib : addLibs)
 	{
@@ -399,43 +382,46 @@ void VersionFile::applyTo(VersionFinal *version)
 		case RawLibrary::Apply:
 		{
 			// QLOG_INFO() << "Applying lib " << lib->name;
-			int index = findLibrary(version->libraries, lib->name);
+			int index = findLibrary(version->libraries, lib->m_name);
 			if (index >= 0)
 			{
 				auto library = version->libraries[index];
-				if (!lib->url.isNull())
+				if (!lib->m_base_url.isNull())
 				{
-					library->setBaseUrl(lib->url);
+					library->setBaseUrl(lib->m_base_url);
 				}
-				if (!lib->hint.isNull())
+				if (!lib->m_hint.isNull())
 				{
-					library->setHint(lib->hint);
+					library->setHint(lib->m_hint);
 				}
-				if (!lib->absoluteUrl.isNull())
+				if (!lib->m_absolute_url.isNull())
 				{
-					library->setAbsoluteUrl(lib->absoluteUrl);
+					library->setAbsoluteUrl(lib->m_absolute_url);
 				}
 				if (lib->applyExcludes)
 				{
-					library->extract_excludes = lib->excludes;
+					library->extract_excludes = lib->extract_excludes;
 				}
-				if (lib->applyNatives)
+				if (lib->isNative())
 				{
-					library->clearSuffixes();
+					// library->clearSuffixes();
+					library->m_native_suffixes = lib->m_native_suffixes;
+					/*
 					for (auto native : lib->natives)
 					{
 						library->addNative(native.first, native.second);
 					}
+					*/
 				}
 				if (lib->applyRules)
 				{
-					library->setRules(lib->rules);
+					library->setRules(lib->m_rules);
 				}
 				library->finalize();
 			}
 			else
 			{
-				QLOG_WARN() << "Couldn't find" << lib->name << "(skipping)";
+				QLOG_WARN() << "Couldn't find" << lib->m_name << "(skipping)";
 			}
 			break;
 		}
@@ -443,24 +429,24 @@ void VersionFile::applyTo(VersionFinal *version)
 		case RawLibrary::Prepend:
 		{
 			// QLOG_INFO() << "Adding lib " << lib->name;
-			const int startOfVersion = lib->name.lastIndexOf(':') + 1;
+			const int startOfVersion = lib->m_name.lastIndexOf(':') + 1;
 			const int index = findLibrary(
-				version->libraries, QString(lib->name).replace(startOfVersion, INT_MAX, '*'));
+				version->libraries, QString(lib->m_name).replace(startOfVersion, INT_MAX, '*'));
 			if (index < 0)
 			{
 				if (lib->insertType == RawLibrary::Append)
 				{
-					version->libraries.append(createLibrary(lib));
+					version->libraries.append(OneSixLibrary::fromRawLibrary(lib));
 				}
 				else
 				{
-					version->libraries.prepend(createLibrary(lib));
+					version->libraries.prepend(OneSixLibrary::fromRawLibrary(lib));
 				}
 			}
 			else
 			{
 				auto otherLib = version->libraries.at(index);
-				const Util::Version ourVersion = lib->name.mid(startOfVersion, INT_MAX);
+				const Util::Version ourVersion = lib->m_name.mid(startOfVersion, INT_MAX);
 				const Util::Version otherVersion = otherLib->version();
 				// if the existing version is a hard dependency we can either use it or
 				// fail, but we can't change it
@@ -474,7 +460,7 @@ void VersionFile::applyTo(VersionFinal *version)
 						throw VersionBuildError(
 							QObject::tr(
 								"Error resolving library dependencies between %1 and %2 in %3.")
-								.arg(otherLib->rawName(), lib->name, filename));
+								.arg(otherLib->rawName(), lib->m_name, filename));
 					}
 					else
 					{
@@ -486,7 +472,7 @@ void VersionFile::applyTo(VersionFinal *version)
 					// if we are higher it means we should update
 					if (ourVersion > otherVersion)
 					{
-						auto library = createLibrary(lib);
+						auto library = OneSixLibrary::fromRawLibrary(lib);
 						if (Util::Version(otherLib->minVersion) < ourVersion)
 						{
 							library->minVersion = ourVersion.toString();
@@ -501,7 +487,7 @@ void VersionFile::applyTo(VersionFinal *version)
 						{
 							throw VersionBuildError(QObject::tr(
 								"Error resolving library dependencies between %1 and %2 in %3.")
-														.arg(otherLib->rawName(), lib->name,
+														.arg(otherLib->rawName(), lib->m_name,
 															 filename));
 						}
 					}
@@ -512,10 +498,10 @@ void VersionFile::applyTo(VersionFinal *version)
 		case RawLibrary::Replace:
 		{
 			QString toReplace;
-			if(lib->insertData.isEmpty())
+			if (lib->insertData.isEmpty())
 			{
-				const int startOfVersion = lib->name.lastIndexOf(':') + 1;
-				toReplace = QString(lib->name).replace(startOfVersion, INT_MAX, '*');
+				const int startOfVersion = lib->m_name.lastIndexOf(':') + 1;
+				toReplace = QString(lib->m_name).replace(startOfVersion, INT_MAX, '*');
 			}
 			else
 				toReplace = lib->insertData;
@@ -523,7 +509,7 @@ void VersionFile::applyTo(VersionFinal *version)
 			int index = findLibrary(version->libraries, toReplace);
 			if (index >= 0)
 			{
-				version->libraries.replace(index, createLibrary(lib));
+				version->libraries.replace(index, OneSixLibrary::fromRawLibrary(lib));
 			}
 			else
 			{
diff --git a/logic/minecraft/VersionFile.h b/logic/minecraft/VersionFile.h
new file mode 100644
index 00000000..186f4335
--- /dev/null
+++ b/logic/minecraft/VersionFile.h
@@ -0,0 +1,103 @@
+#pragma once
+
+#include <QString>
+#include <QStringList>
+#include <QDateTime>
+#include <memory>
+#include "logic/minecraft/OpSys.h"
+#include "logic/minecraft/OneSixRule.h"
+#include "VersionPatch.h"
+#include "MMCError.h"
+#include "OneSixLibrary.h"
+#include "JarMod.h"
+
+class InstanceVersion;
+struct VersionFile;
+
+typedef std::shared_ptr<VersionFile> VersionFilePtr;
+class VersionFile : public VersionPatch
+{
+public: /* methods */
+	static VersionFilePtr fromJson(const QJsonDocument &doc, const QString &filename,
+								   const bool requireOrder, const bool isFTB = false);
+	QJsonDocument toJson(bool saveOrder);
+
+	virtual void applyTo(InstanceVersion *version) override;
+	virtual bool isMinecraftVersion() override;
+	virtual bool hasJarMods() override;
+	virtual int getOrder() override
+	{
+		return order;
+	}
+	virtual void setOrder(int order) override
+	{
+		this->order = order;
+	}
+	virtual QList<JarmodPtr> getJarMods() override
+	{
+		return jarMods;
+	}
+	virtual QString getPatchID() override
+	{
+		return fileId;
+	}
+	virtual QString getPatchName() override
+	{
+		return name;
+	}
+	virtual QString getPatchVersion() override
+	{
+		return version;
+	}
+	virtual QString getPatchFilename() override
+	{
+		return filename;
+	}
+
+public: /* data */
+	int order = 0;
+	QString name;
+	QString fileId;
+	QString version;
+	// TODO use the mcVersion to determine if a version file should be removed on update
+	QString mcVersion;
+	QString filename;
+	// TODO requirements
+	// QMap<QString, QString> requirements;
+	QString id;
+	QString mainClass;
+	QString appletClass;
+	QString overwriteMinecraftArguments;
+	QString addMinecraftArguments;
+	QString removeMinecraftArguments;
+	QString processArguments;
+	QString type;
+
+	/// the time this version was actually released by Mojang, as string and as QDateTime
+	QString m_releaseTimeString;
+	QDateTime m_releaseTime;
+
+	/// the time this version was last updated by Mojang, as string and as QDateTime
+	QString m_updateTimeString;
+	QDateTime m_updateTime;
+
+	/// asset group used by this ... thing.
+	QString assets;
+	int minimumLauncherVersion = -1;
+
+	bool shouldOverwriteTweakers = false;
+	QStringList overwriteTweakers;
+	QStringList addTweakers;
+	QStringList removeTweakers;
+
+	bool shouldOverwriteLibs = false;
+	QList<RawLibraryPtr> overwriteLibs;
+	QList<RawLibraryPtr> addLibs;
+	QList<QString> removeLibs;
+
+	QSet<QString> traits;
+
+	QList<JarmodPtr> jarMods;
+};
+
+
diff --git a/logic/minecraft/VersionPatch.h b/logic/minecraft/VersionPatch.h
new file mode 100644
index 00000000..1dd30e79
--- /dev/null
+++ b/logic/minecraft/VersionPatch.h
@@ -0,0 +1,31 @@
+#pragma once
+
+#include <memory>
+#include <QList>
+#include "JarMod.h"
+
+class InstanceVersion;
+class VersionPatch
+{
+public:
+	virtual ~VersionPatch(){};
+	virtual void applyTo(InstanceVersion *version) = 0;
+	
+	virtual bool isMinecraftVersion() = 0;
+	virtual bool hasJarMods() = 0;
+	virtual QList<JarmodPtr> getJarMods() = 0;
+	
+	virtual bool isMoveable()
+	{
+		return getOrder() >= 0;
+	}
+	virtual void setOrder(int order) = 0;
+	virtual int getOrder() = 0;
+	
+	virtual QString getPatchID() = 0;
+	virtual QString getPatchName() = 0;
+	virtual QString getPatchVersion() = 0;
+	virtual QString getPatchFilename() = 0;
+};
+
+typedef std::shared_ptr<VersionPatch> VersionPatchPtr;
diff --git a/logic/minecraft/VersionSource.h b/logic/minecraft/VersionSource.h
new file mode 100644
index 00000000..75b2c24b
--- /dev/null
+++ b/logic/minecraft/VersionSource.h
@@ -0,0 +1,9 @@
+#pragma once
+
+/// where is a version from?
+enum VersionSource
+{
+	Builtin, //!< version loaded from the internal resources.
+	Local, //!< version loaded from a file in the cache.
+	Remote, //!< incomplete version on a remote server.
+};
\ No newline at end of file
diff --git a/logic/net/NetJob.h b/logic/net/NetJob.h
index 2df8428b..d05e7b6f 100644
--- a/logic/net/NetJob.h
+++ b/logic/net/NetJob.h
@@ -21,7 +21,6 @@
 #include "MD5EtagDownload.h"
 #include "CacheDownload.h"
 #include "HttpMetaCache.h"
-#include "ForgeXzDownload.h"
 #include "logic/tasks/ProgressProvider.h"
 
 class NetJob;
diff --git a/logic/screenshots/ImgurAlbumCreation.cpp b/logic/screenshots/ImgurAlbumCreation.cpp
index e473952e..91cf4bb1 100644
--- a/logic/screenshots/ImgurAlbumCreation.cpp
+++ b/logic/screenshots/ImgurAlbumCreation.cpp
@@ -4,8 +4,8 @@
 #include <QJsonDocument>
 #include <QJsonObject>
 #include <QUrl>
+#include <QStringList>
 
-#include "logic/screenshots//ScreenshotList.h"
 #include "logic/net/URLConstants.h"
 #include "MultiMC.h"
 #include "logger/QsLog.h"
@@ -28,7 +28,7 @@ void ImgurAlbumCreation::start()
 	QStringList ids;
 	for (auto shot : m_screenshots)
 	{
-		ids.append(shot->imgurId);
+		ids.append(shot->m_imgurId);
 	}
 
 	const QByteArray data = "ids=" + ids.join(',').toUtf8() + "&title=Minecraft%20Screenshots&privacy=hidden";
diff --git a/logic/screenshots/ImgurUpload.cpp b/logic/screenshots/ImgurUpload.cpp
index 62033ef5..f305aec0 100644
--- a/logic/screenshots/ImgurUpload.cpp
+++ b/logic/screenshots/ImgurUpload.cpp
@@ -8,7 +8,6 @@
 #include <QFile>
 #include <QUrl>
 
-#include "logic/screenshots/ScreenshotList.h"
 #include "logic/net/URLConstants.h"
 #include "MultiMC.h"
 #include "logger/QsLog.h"
@@ -27,7 +26,7 @@ void ImgurUpload::start()
 	request.setRawHeader("Authorization", "Client-ID 5b97b0713fba4a3");
 	request.setRawHeader("Accept", "application/json");
 
-	QFile f(m_shot->file);
+	QFile f(m_shot->m_file.absoluteFilePath());
 	if (!f.open(QFile::ReadOnly))
 	{
 		emit failed(m_index_within_job);
@@ -46,7 +45,7 @@ void ImgurUpload::start()
 	multipart->append(typePart);
 	QHttpPart namePart;
 	namePart.setHeader(QNetworkRequest::ContentDispositionHeader, "form-data; name=\"name\"");
-	namePart.setBody(m_shot->timestamp.toString(Qt::ISODate).toUtf8());
+	namePart.setBody(m_shot->m_file.baseName().toUtf8());
 	multipart->append(namePart);
 
 	auto worker = MMC->qnam();
@@ -84,8 +83,8 @@ void ImgurUpload::downloadFinished()
 			emit failed(m_index_within_job);
 			return;
 		}
-		m_shot->imgurId = object.value("data").toObject().value("id").toString();
-		m_shot->url = object.value("data").toObject().value("link").toString();
+		m_shot->m_imgurId = object.value("data").toObject().value("id").toString();
+		m_shot->m_url = object.value("data").toObject().value("link").toString();
 		m_status = Job_Finished;
 		emit succeeded(m_index_within_job);
 		return;
diff --git a/logic/screenshots/Screenshot.cpp b/logic/screenshots/Screenshot.cpp
deleted file mode 100644
index 882e491f..00000000
--- a/logic/screenshots/Screenshot.cpp
+++ /dev/null
@@ -1,14 +0,0 @@
-#include "Screenshot.h"
-#include <QImage>
-#include <QIcon>
-QIcon ScreenShot::getImage()
-{
-	if(!imageloaded)
-	{
-		QImage image(file);
-		QImage thumbnail = image.scaledToWidth(256, Qt::SmoothTransformation);
-		m_image = QIcon(QPixmap::fromImage(thumbnail));
-		imageloaded = true;
-	}
-	return m_image;
-}
diff --git a/logic/screenshots/Screenshot.h b/logic/screenshots/Screenshot.h
index 815c0d47..b48cbe99 100644
--- a/logic/screenshots/Screenshot.h
+++ b/logic/screenshots/Screenshot.h
@@ -2,18 +2,18 @@
 
 #include <QDateTime>
 #include <QString>
+#include <QFileInfo>
 #include <memory>
-#include <QIcon>
 
 struct ScreenShot
 {
-	QIcon getImage();
-	QIcon m_image;
-	bool imageloaded = false;
-	QDateTime timestamp;
-	QString file;
-	QString url;
-	QString imgurId;
+	ScreenShot(QFileInfo file)
+	{
+		m_file = file;
+	}
+	QFileInfo m_file;
+	QString m_url;
+	QString m_imgurId;
 };
 
 typedef std::shared_ptr<ScreenShot> ScreenshotPtr;
diff --git a/logic/screenshots/ScreenshotList.cpp b/logic/screenshots/ScreenshotList.cpp
deleted file mode 100644
index a34f4d46..00000000
--- a/logic/screenshots/ScreenshotList.cpp
+++ /dev/null
@@ -1,113 +0,0 @@
-#include "ScreenshotList.h"
-#include "gui/dialogs/ScreenshotDialog.h"
-
-#include <QDir>
-#include <QIcon>
-#include <QList>
-#include "gui/dialogs/ProgressDialog.h"
-#include "gui/dialogs/CustomMessageBox.h"
-
-ScreenshotList::ScreenshotList(InstancePtr instance, QObject *parent)
-	: QAbstractListModel(parent), m_instance(instance)
-{
-}
-
-int ScreenshotList::rowCount(const QModelIndex &) const
-{
-	return m_screenshots.size();
-}
-
-QVariant ScreenshotList::data(const QModelIndex &index, int role) const
-{
-	if (index.row() >= m_screenshots.size() || index.row() < 0)
-		return QVariant();
-
-	switch (role)
-	{
-	case Qt::DecorationRole:
-		return m_screenshots.at(index.row())->getImage();
-	case Qt::DisplayRole:
-		return m_screenshots.at(index.row())->timestamp.toString("yyyy-MM-dd HH:mm:ss");
-	case Qt::ToolTipRole:
-		return m_screenshots.at(index.row())->timestamp.toString("yyyy-MM-dd HH:mm:ss");
-	case Qt::TextAlignmentRole:
-		return (int)(Qt::AlignHCenter | Qt::AlignVCenter);
-	default:
-		return QVariant();
-	}
-}
-
-QVariant ScreenshotList::headerData(int section, Qt::Orientation orientation, int role) const
-{
-	return QVariant();
-}
-
-Qt::ItemFlags ScreenshotList::flags(const QModelIndex &index) const
-{
-	return Qt::ItemIsSelectable | Qt::ItemIsEnabled;
-}
-
-Task *ScreenshotList::load()
-{
-	return new ScreenshotLoadTask(this);
-}
-
-ScreenshotLoadTask::ScreenshotLoadTask(ScreenshotList *list) : m_list(list)
-{
-}
-
-ScreenshotLoadTask::~ScreenshotLoadTask()
-{
-}
-
-void ScreenshotLoadTask::executeTask()
-{
-	auto dir = QDir(m_list->instance()->minecraftRoot());
-	if (!dir.cd("screenshots"))
-	{
-		emitFailed("Selected instance does not have any screenshots!");
-		return;
-	}
-	dir.setNameFilters(QStringList() << "*.png");
-	this->m_results.clear();
-	for (auto file : dir.entryList())
-	{
-		ScreenShot *shot = new ScreenShot();
-		shot->timestamp = QDateTime::fromString(file, "yyyy-MM-dd_HH.mm.ss.png");
-		shot->file = dir.absoluteFilePath(file);
-		m_results.append(ScreenshotPtr(shot));
-	}
-	m_list->loadShots(m_results);
-	emitSucceeded();
-}
-
-void ScreenshotList::deleteSelected(ScreenshotDialog *dialog)
-{
-	auto screens = dialog->selected();
-	if (screens.isEmpty())
-	{
-		return;
-	}
-	beginResetModel();
-	QList<std::shared_ptr<ScreenShot>>::const_iterator it;
-	for (it = screens.cbegin(); it != screens.cend(); it++)
-	{
-		auto shot = *it;
-		if (!QFile(shot->file).remove())
-		{
-			CustomMessageBox::selectable(dialog, tr("Error!"),
-										 tr("Failed to delete screenshots!"),
-										 QMessageBox::Warning)->exec();
-			break;
-		}
-	}
-	ProgressDialog refresh(dialog);
-	Task *t = load();
-	if (refresh.exec(t) != QDialog::Accepted)
-	{
-		CustomMessageBox::selectable(dialog, tr("Error!"),
-									 tr("Unable to refresh list: %1").arg(t->failReason()),
-									 QMessageBox::Warning)->exec();
-	}
-	endResetModel();
-}
diff --git a/logic/screenshots/ScreenshotList.h b/logic/screenshots/ScreenshotList.h
deleted file mode 100644
index dc26a698..00000000
--- a/logic/screenshots/ScreenshotList.h
+++ /dev/null
@@ -1,70 +0,0 @@
-#pragma once
-
-#include <QAbstractListModel>
-#include "logic/BaseInstance.h"
-#include "logic/tasks/Task.h"
-
-#include "Screenshot.h"
-
-class ScreenshotList : public QAbstractListModel
-{
-	Q_OBJECT
-public:
-	ScreenshotList(InstancePtr instance, QObject *parent = 0);
-
-	QVariant data(const QModelIndex &index, int role) const;
-	QVariant headerData(int section, Qt::Orientation orientation, int role) const;
-
-	int rowCount(const QModelIndex &parent) const;
-
-	Qt::ItemFlags flags(const QModelIndex &index) const;
-
-	Task *load();
-
-	void loadShots(QList<ScreenshotPtr> shots)
-	{
-		m_screenshots = shots;
-	}
-
-	QList<ScreenshotPtr> screenshots() const
-	{
-		return m_screenshots;
-	}
-
-	InstancePtr instance() const
-	{
-		return m_instance;
-	}
-
-	void deleteSelected(class ScreenshotDialog *dialog);
-
-signals:
-
-public
-slots:
-
-private:
-	QList<ScreenshotPtr> m_screenshots;
-	InstancePtr m_instance;
-};
-
-class ScreenshotLoadTask : public Task
-{
-	Q_OBJECT
-
-public:
-	explicit ScreenshotLoadTask(ScreenshotList *list);
-	~ScreenshotLoadTask();
-
-	QList<ScreenshotPtr> screenShots() const
-	{
-		return m_results;
-	}
-
-protected:
-	virtual void executeTask();
-
-private:
-	ScreenshotList *m_list;
-	QList<ScreenshotPtr> m_results;
-};
diff --git a/logic/tasks/ProgressProvider.h b/logic/tasks/ProgressProvider.h
index 15e453a3..dcb71139 100644
--- a/logic/tasks/ProgressProvider.h
+++ b/logic/tasks/ProgressProvider.h
@@ -32,6 +32,7 @@ signals:
 	void status(QString status);
 
 public:
+	virtual ~ProgressProvider() {};
 	virtual QString getStatus() const = 0;
 	virtual void getProgress(qint64 &current, qint64 &total) = 0;
 	virtual bool isRunning() const = 0;