Make 1.6+ work with new instance format.

29 files changed, 929 insertions, 540 deletions

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 0be887dc..57b6352f 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -485,11 +485,13 @@ SET(MULTIMC_SOURCES
 	logic/minecraft/RawLibrary.h
 	logic/minecraft/VersionBuilder.cpp
 	logic/minecraft/VersionBuilder.h
+	logic/minecraft/VersionBuildError.h
 	logic/minecraft/VersionFile.cpp
 	logic/minecraft/VersionFile.h
 	logic/minecraft/VersionFinal.cpp
 	logic/minecraft/VersionFinal.h
 	logic/minecraft/VersionPatch.h
+	logic/minecraft/VersionSource.h
 
 	# Various base classes
 	logic/BaseInstaller.h
diff --git a/logic/MMCJson.cpp b/logic/MMCJson.cpp
index 65423436..f7b4b6b0 100644
--- a/logic/MMCJson.cpp
+++ b/logic/MMCJson.cpp
@@ -11,7 +11,7 @@ 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 +59,24 @@ 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/OneSixUpdate.cpp b/logic/OneSixUpdate.cpp
index f77913dc..2a7bb5b6 100644
--- a/logic/OneSixUpdate.cpp
+++ b/logic/OneSixUpdate.cpp
@@ -34,15 +34,12 @@
 #include "logic/net/URLConstants.h"
 #include "logic/assets/AssetsUtils.h"
 
-OneSixUpdate::OneSixUpdate(OneSixInstance *inst, QObject *parent)
-	: Task(parent), m_inst(inst)
+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("."))
@@ -51,97 +48,37 @@ 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;
-		}
-		// builtins need no updates, so only update for Mojang
-		if(targetVersion->m_versionSource == MinecraftVersion::Mojang)
-		{
-			versionFileStart();
-			return;
-		}
+		// don't do anything if it was invalid
+		emitFailed(tr("The specified Minecraft version is invalid. Choose a different one."));
+		return;
 	}
-	jarlibStart();
-}
-
-void OneSixUpdate::versionFileStart()
-{
-	if (m_inst->providesVersionFile())
+	if (m_inst->providesVersionFile() || !targetVersion->needsUpdate())
 	{
 		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)),
-			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())
+	versionUpdateTask = MMC->minecraftlist()->createUpdateTask(m_inst->intendedVersionId());
+	if (!versionUpdateTask)
 	{
-		finfo.remove();
+		jarlibStart();
+		return;
 	}
-	// NOTE: Version is reloaded in jarlibStart
-	jarlibStart();
+	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)));
+	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()
@@ -236,12 +173,12 @@ 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;
@@ -275,7 +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;
 		}
@@ -312,16 +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
@@ -344,27 +284,27 @@ void OneSixUpdate::jarlibFinished()
 {
 	OneSixInstance *inst = (OneSixInstance *)m_inst;
 	std::shared_ptr<VersionFinal> version = inst->getFullVersion();
-	
+
 	// create stripped jar, if needed
-	if(version->hasJarMods())
+	if (version->hasJarMods())
 	{
-		//FIXME: good candidate for moving elsewhere (jar location resolving/version caching).
+		// 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();
-		
-		if(entry->md5sum != jarHashOnEntry || !QFileInfo::exists(fullStrippedJarPath))
+
+		if (entry->md5sum != jarHashOnEntry || !QFileInfo::exists(fullStrippedJarPath))
 		{
 			stripJar(fullJarPath, fullStrippedJarPath);
 		}
 	}
-	if(version->traits.contains("legacyFML"))
+	if (version->traits.contains("legacyFML"))
 	{
 		fmllibsStart();
 	}
@@ -378,7 +318,8 @@ 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)
@@ -462,7 +403,6 @@ bool OneSixUpdate::MergeZipFiles(QuaZip *into, QString from)
 	return true;
 }
 
-
 void OneSixUpdate::fmllibsStart()
 {
 	// Get the mod list
@@ -471,7 +411,7 @@ void OneSixUpdate::fmllibsStart()
 	bool forge_present = false;
 
 	QString version = inst->intendedVersionId();
-	auto & fmlLibsMapping = g_VersionFilterData.fmlLibsMapping;
+	auto &fmlLibsMapping = g_VersionFilterData.fmlLibsMapping;
 	if (!fmlLibsMapping.contains(version))
 	{
 		assetIndexStart();
@@ -528,7 +468,7 @@ void OneSixUpdate::fmllibsStart()
 void OneSixUpdate::fmllibsFinished()
 {
 	legacyDownloadJob.reset();
-	if(!fmlLibsToProcess.isEmpty())
+	if (!fmlLibsToProcess.isEmpty())
 	{
 		setStatus(tr("Copying FML libraries into the instance..."));
 		OneSixInstance *inst = (OneSixInstance *)m_inst;
@@ -539,7 +479,7 @@ void OneSixUpdate::fmllibsFinished()
 			progress(index, fmlLibsToProcess.size());
 			auto entry = metacache->resolveEntry("fmllibs", lib.filename);
 			auto path = PathCombine(inst->libDir(), lib.filename);
-			if(!ensureFilePathExists(path))
+			if (!ensureFilePathExists(path))
 			{
 				emitFailed(tr("Failed creating FML library folder inside the instance."));
 				return;
diff --git a/logic/OneSixUpdate.h b/logic/OneSixUpdate.h
index 00f7c135..139143db 100644
--- a/logic/OneSixUpdate.h
+++ b/logic/OneSixUpdate.h
@@ -36,9 +36,7 @@ public:
 
 private
 slots:
-	void versionFileStart();
-	void versionFileFinished();
-	void versionFileFailed();
+	void versionUpdateFailed(QString reason);
 
 	void jarlibStart();
 	void jarlibFinished();
@@ -58,12 +56,14 @@ slots:
 	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/VersionFilterData.cpp b/logic/VersionFilterData.cpp
index 8322dad4..8b521266 100644
--- a/logic/VersionFilterData.cpp
+++ b/logic/VersionFilterData.cpp
@@ -1,4 +1,5 @@
 #include "VersionFilterData.h"
+#include "minecraft/ParseUtils.h"
 
 extern VersionFilterData g_VersionFilterData = VersionFilterData();
 
@@ -57,8 +58,11 @@ VersionFilterData::VersionFilterData()
 
 	// don't use installers for those.
 	forgeInstallerBlacklist = QSet<QString>({"1.5.2"});
-	legacyLaunchWhitelist =
-		QSet<QString>({"1.5.2", "1.5.1", "1.5",   "1.4.7", "1.4.6", "1.4.5", "1.4.4", "1.4.3",
-					   "1.4.2", "1.4.1", "1.4",   "1.3.2", "1.3.1", "1.3",   "1.2.5", "1.2.4",
-					   "1.2.3", "1.2.2", "1.2.1", "1.1",   "1.0.1", "1.0"});
+	// 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
index 562654a9..e010adc7 100644
--- a/logic/VersionFilterData.h
+++ b/logic/VersionFilterData.h
@@ -2,6 +2,7 @@
 #include <QMap>
 #include <QString>
 #include <QSet>
+#include <QDateTime>
 
 struct FMLlib
 {
@@ -17,7 +18,9 @@ struct VersionFilterData
 	QMap<QString, QList<FMLlib>> fmlLibsMapping;
 	// set of minecraft versions for which using forge installers is blacklisted
 	QSet<QString> forgeInstallerBlacklist;
-	// set of 'legacy' versions (ones that use the legacy launch)
-	QSet<QString> legacyLaunchWhitelist;
+	// 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/minecraft/JarMod.cpp b/logic/minecraft/JarMod.cpp
index 99a30aa5..18a9411c 100644
--- a/logic/minecraft/JarMod.cpp
+++ b/logic/minecraft/JarMod.cpp
@@ -1,5 +1,6 @@
 #include "JarMod.h"
 #include "logic/MMCJson.h"
+using namespace MMCJson;
 
 JarmodPtr Jarmod::fromJson(const QJsonObject &libObj, const QString &filename)
 {
@@ -28,6 +29,7 @@ JarmodPtr Jarmod::fromJson(const QJsonObject &libObj, const QString &filename)
 	};
 
 	readString("url", out->baseurl);
+	readString("MMC-hint", out->hint);
 	readString("MMC-absoluteUrl", out->absoluteUrl);
 	if(!out->baseurl.isEmpty() && out->absoluteUrl.isEmpty())
 	{
@@ -36,6 +38,16 @@ JarmodPtr Jarmod::fromJson(const QJsonObject &libObj, const QString &filename)
 	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())
diff --git a/logic/minecraft/JarMod.h b/logic/minecraft/JarMod.h
index da5d8db0..c438dbcd 100644
--- a/logic/minecraft/JarMod.h
+++ b/logic/minecraft/JarMod.h
@@ -8,6 +8,7 @@ class Jarmod
 {
 public: /* methods */
 	static JarmodPtr fromJson(const QJsonObject &libObj, const QString &filename);
+	QJsonObject toJson();
 	QString url();
 public: /* data */
 	QString name;
diff --git a/logic/minecraft/MinecraftVersion.cpp b/logic/minecraft/MinecraftVersion.cpp
index 2191e8af..e0cbce8d 100644
--- a/logic/minecraft/MinecraftVersion.cpp
+++ b/logic/minecraft/MinecraftVersion.cpp
@@ -1,29 +1,26 @@
 #include "MinecraftVersion.h"
 #include "VersionFinal.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 (is_latest && is_snapshot)
-	{
-		return QObject::tr("Latest snapshot");
-	}
-	else if (is_latest)
-	{
-		return QObject::tr("Latest release");
-	}
-	else if (is_snapshot)
+	if (is_snapshot)
 	{
 		return QObject::tr("Snapshot");
 	}
@@ -32,22 +29,41 @@ QString MinecraftVersion::typeString() const
 		return QObject::tr("Regular release");
 	}
 }
+
 bool MinecraftVersion::hasJarMods()
 {
 	return false;
 }
-bool MinecraftVersion::isVanilla()
+
+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(VersionFinal *version)
+{
+	QFileInfo versionFile(QString("versions/%1/%1.json").arg(m_descriptor));
+	
+	auto versionObj = VersionBuilder::parseJsonFile(versionFile, false, false);
+	versionObj->applyTo(version);
+}
+
 void MinecraftVersion::applyTo(VersionFinal *version)
 {
-	// FIXME: make this work.
-	if(m_versionSource != Builtin)
+	// 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;
@@ -81,15 +97,35 @@ void MinecraftVersion::applyTo(VersionFinal *version)
 	}
 	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
index 6a1c54cb..02afd709 100644
--- a/logic/minecraft/MinecraftVersion.h
+++ b/logic/minecraft/MinecraftVersion.h
@@ -22,26 +22,49 @@
 #include "logic/BaseVersion.h"
 #include "VersionPatch.h"
 #include "VersionFile.h"
+#include "VersionSource.h"
 
 class VersionFinal;
+class MinecraftVersion;
+typedef std::shared_ptr<MinecraftVersion> MinecraftVersionPtr;
 
-struct MinecraftVersion : public BaseVersion, public VersionPatch
+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(VersionFinal *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(VersionFinal *version);
+
+public: /* data */
 	/// The URL that this version will be downloaded from. maybe.
 	QString download_url;
 
-	/// is this the latest version?
-	bool is_latest = false;
-
 	/// is this a snapshot?
 	bool is_snapshot = false;
 
-	/// where is this from?
-	enum VersionSource
-	{
-		Builtin,
-		Mojang
-	} m_versionSource = Builtin;
+	VersionSource m_versionSource = Builtin;
 
 	/// the human readable version name
 	QString m_name;
@@ -74,31 +97,7 @@ struct MinecraftVersion : public BaseVersion, public VersionPatch
 
 	/// order of this file... default = -2
 	int order = -2;
-
-	bool usesLegacyLauncher();
-	virtual QString descriptor() override;
-	virtual QString name() override;
-	virtual QString typeString() const override;
-	virtual bool hasJarMods() override;
-	virtual bool isVanilla() override;
-	virtual void applyTo(VersionFinal *version) override;
-	virtual int getOrder();
-	virtual void setOrder(int order);
-	virtual QList<JarmodPtr> getJarMods() override;
-	virtual QString getPatchID()
-	{
-		return "net.minecraft";
-	}
-	virtual QString getPatchVersion()
-	{
-		return m_descriptor;
-	}
-	virtual QString getPatchName()
-	{
-		return "Minecraft";
-	}
-	virtual QString getPatchFilename()
-	{
-		return QString();
-	};
+	
+	/// an update available from Mojang
+	MinecraftVersionPtr upstreamUpdate;
 };
diff --git a/logic/minecraft/MinecraftVersionList.cpp b/logic/minecraft/MinecraftVersionList.cpp
index 1aa220e8..5a5ea348 100644
--- a/logic/minecraft/MinecraftVersionList.cpp
+++ b/logic/minecraft/MinecraftVersionList.cpp
@@ -13,27 +13,35 @@
  * limitations under the License.
  */
 
-#include "MinecraftVersionList.h"
-#include "MultiMC.h"
-#include "logic/net/URLConstants.h"
+#include <QtXml>
 #include "logic/MMCJson.h"
-#include "ParseUtils.h"
+#include <QtAlgorithms>
+#include <QtNetwork>
 
-#include <QtXml>
+#include "MultiMC.h"
+#include "MMCError.h"
 
-#include <QJsonDocument>
-#include <QJsonObject>
-#include <QJsonArray>
-#include <QJsonValue>
-#include <QJsonParseError>
+#include "MinecraftVersionList.h"
+#include "logic/net/URLConstants.h"
 
-#include <QtAlgorithms>
+#include "ParseUtils.h"
+#include "VersionBuilder.h"
+#include <logic/VersionFilterData.h>
+#include <pathutils.h>
 
-#include <QtNetwork>
+class ListLoadError : public MMCError
+{
+public:
+	ListLoadError(QString cause) : MMCError(cause) {};
+	virtual ~ListLoadError() noexcept
+	{
+	}
+};
 
 MinecraftVersionList::MinecraftVersionList(QObject *parent) : BaseVersionList(parent)
 {
 	loadBuiltinList();
+	loadCachedList();
 }
 
 Task *MinecraftVersionList::getLoadTask()
@@ -68,6 +76,35 @@ void MinecraftVersionList::sortInternal()
 	qSort(m_vlist.begin(), m_vlist.end(), cmpVersions);
 }
 
+void MinecraftVersionList::loadCachedList()
+{
+	QFile localIndex("versions/versions.json");
+	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
+	{
+		loadMojangList(data, 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.close();
+		localIndex.remove();
+		return;
+	}
+	m_hasLocalIndex = true;
+}
+
 void MinecraftVersionList::loadBuiltinList()
 {
 	// grab the version list data from internal resources.
@@ -93,19 +130,22 @@ void MinecraftVersionList::loadBuiltinList()
 			continue;
 		}
 
+		if (g_VersionFilterData.legacyBlacklist.contains(versionID))
+		{
+			QLOG_ERROR() << "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.
-		try
-		{
-			parse_timestamp(versionObj.value("releaseTime").toString(""),
-							mcVersion->m_releaseTimeString, mcVersion->m_releaseTime);
-		}
-		catch (MMCError &e)
+		if (!parse_timestamp(versionObj.value("releaseTime").toString(""),
+							 mcVersion->m_releaseTimeString, mcVersion->m_releaseTime))
 		{
-			QLOG_ERROR() << "Error while parsing version" << versionID << ":" << e.cause();
+			QLOG_ERROR() << "Error while parsing version" << versionID
+						 << ": invalid version timestamp";
 			continue;
 		}
 
@@ -113,7 +153,7 @@ void MinecraftVersionList::loadBuiltinList()
 		mcVersion->download_url =
 			"http://" + URLConstants::AWS_DOWNLOAD_VERSIONS + versionID + "/";
 
-		mcVersion->m_versionSource = MinecraftVersion::Builtin;
+		mcVersion->m_versionSource = Builtin;
 		mcVersion->m_appletClass = versionObj.value("appletClass").toString("");
 		mcVersion->m_mainClass = versionObj.value("mainClass").toString("");
 		mcVersion->m_processArguments = versionObj.value("processArguments").toString("legacy");
@@ -124,10 +164,141 @@ void MinecraftVersionList::loadBuiltinList()
 				mcVersion->m_traits.insert(MMCJson::ensureString(traitVal));
 			}
 		}
+		m_lookup[versionID] = mcVersion;
 		m_vlist.append(mcVersion);
 	}
 }
 
+void MinecraftVersionList::loadMojangList(QByteArray data, VersionSource source)
+{
+	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()));
+	}
+	
+	QLOG_INFO() << ((source == Remote) ? "Remote version list: " : "Local version list:") << data;
+	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)
+	{
+		bool is_snapshot = false;
+
+		// 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_ERROR() << "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)
+		{
+			QLOG_ERROR() << "Ignoring Mojang version: " << versionID;
+			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")
+		{
+			is_snapshot = false;
+		}
+		else if (versionTypeStr == "snapshot") // It's a snapshot... yay
+		{
+			is_snapshot = true;
+		}
+		else if (versionTypeStr == "old_alpha")
+		{
+			is_snapshot = false;
+		}
+		else if (versionTypeStr == "old_beta")
+		{
+			is_snapshot = false;
+		}
+		else
+		{
+			// FIXME: log this somewhere
+			continue;
+		}
+		mcVersion->m_type = versionTypeStr;
+		mcVersion->is_snapshot = is_snapshot;
+		tempList.append(mcVersion);
+	}
+	updateListData(tempList);
+}
+
 void MinecraftVersionList::sort()
 {
 	beginResetModel();
@@ -137,14 +308,8 @@ void MinecraftVersionList::sort()
 
 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);
-		}
-	}
+	if(m_lookup.contains(m_latestReleaseID))
+		return m_lookup[m_latestReleaseID];
 	return BaseVersionPtr();
 }
 
@@ -154,17 +319,29 @@ void MinecraftVersionList::updateListData(QList<BaseVersionPtr> versions)
 	for (auto version : versions)
 	{
 		auto descr = version->descriptor();
-		for (auto builtin_v : m_vlist)
+
+		if (!m_lookup.contains(descr))
 		{
-			if (descr == builtin_v->descriptor())
-			{
-				goto SKIP_THIS_ONE;
-			}
+			m_vlist.append(version);
+			continue;
 		}
-		m_vlist.append(version);
-	SKIP_THIS_ONE:
-	{
-	}
+		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;
 	}
 	m_loaded = true;
 	sortInternal();
@@ -187,10 +364,6 @@ MCVListLoadTask::MCVListLoadTask(MinecraftVersionList *vlist)
 	vlistReply = nullptr;
 }
 
-MCVListLoadTask::~MCVListLoadTask()
-{
-}
-
 void MCVListLoadTask::executeTask()
 {
 	setStatus(tr("Loading instance version list..."));
@@ -209,133 +382,196 @@ void MCVListLoadTask::list_downloaded()
 		return;
 	}
 
-	auto foo = vlistReply->readAll();
-	QJsonParseError jsonError;
-	QLOG_INFO() << foo;
-	QJsonDocument jsonDoc = QJsonDocument::fromJson(foo, &jsonError);
+	auto data = vlistReply->readAll();
 	vlistReply->deleteLater();
-
-	if (jsonError.error != QJsonParseError::NoError)
+	try
 	{
-		emitFailed("Error parsing version list JSON:" + jsonError.errorString());
-		return;
+		m_list->loadMojangList(data, Remote);
 	}
-
-	if (!jsonDoc.isObject())
+	catch (MMCError &e)
 	{
-		emitFailed("Error parsing version list JSON: jsonDoc is not an object");
+		emitFailed(e.cause());
 		return;
 	}
 
-	QJsonObject root = jsonDoc.object();
+	emitSucceeded();
+	return;
+}
 
-	QString latestReleaseID = "INVALID";
-	QString latestSnapshotID = "INVALID";
-	try
+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)
 	{
-		QJsonObject latest = MMCJson::ensureObject(root.value("latest"));
-		latestReleaseID = MMCJson::ensureString(latest.value("release"));
-		latestSnapshotID = MMCJson::ensureString(latest.value("snapshot"));
+		emitFailed(tr("The download version file is not valid."));
+		return;
 	}
-	catch (MMCError &err)
+	VersionFilePtr file;
+	try
 	{
-		QLOG_ERROR()
-			<< tr("Error parsing version list JSON: couldn't determine latest versions");
+		file = VersionFile::fromJson(jsonDoc, "net.minecraft.json", false);
 	}
-
-	// Now, get the array of versions.
-	if (!root.value("versions").isArray())
+	catch (MMCError &e)
 	{
-		emitFailed(
-			"Error parsing version list JSON: version list object is missing 'versions' array");
+		emitFailed(tr("Couldn't process version file: %1").arg(e.cause()));
 		return;
 	}
-	QJsonArray versions = root.value("versions").toArray();
-
-	QList<BaseVersionPtr> tempList;
-	for (auto version : versions)
+	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)
 	{
-		bool is_snapshot = false;
-		bool is_latest = false;
-
-		// Load the version info.
-		if (!version.isObject())
+		if (lwjglFilter.contains(lib->fullname()))
 		{
-			QLOG_ERROR() << "Error while parsing version list : invalid JSON structure";
-			continue;
+			lwjglLibs.append(lib);
 		}
-		QJsonObject versionObj = version.toObject();
-		QString versionID = versionObj.value("id").toString("");
-		if (versionID.isEmpty())
+		else
 		{
-			QLOG_ERROR() << "Error while parsing version : version ID is missing";
-			continue;
+			filteredLibs.append(lib);
 		}
-		// Get the download URL.
-		QString dlUrl = "http://" + URLConstants::AWS_DOWNLOAD_VERSIONS + versionID + "/";
+	}
+	file->overwriteLibs = filteredLibs;
 
-		// 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;
+	// TODO: recognize and add LWJGL versions here.
 
-		try
-		{
-			// Parse the timestamps.
-			parse_timestamp(versionObj.value("releaseTime").toString(""),
-							mcVersion->m_releaseTimeString, mcVersion->m_releaseTime);
+	file->fileId = "net.minecraft";
 
-			parse_timestamp(versionObj.value("time").toString(""),
-							mcVersion->m_updateTimeString, mcVersion->m_updateTime);
-		}
-		catch (MMCError &e)
-		{
-			QLOG_ERROR() << "Error while parsing version" << versionID << ":" << e.cause();
+	// now dump the file to disk
+	auto doc = file->toJson(false);
+	auto newdata = doc.toJson();
+	QLOG_INFO() << newdata;
+	QString targetPath = "versions/" + versionToUpdate + "/" + versionToUpdate + ".json";
+	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("versions/versions.json"))
+		return;
+	QSaveFile tfile("versions/versions.json");
+	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;
 
-		mcVersion->m_versionSource = MinecraftVersion::Builtin;
-		mcVersion->download_url = dlUrl;
+		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);
+	QJsonDocument doc(toplevel);
+	QByteArray jsonData = doc.toJson();
+	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())
 		{
-			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")
-			{
-				is_latest = (versionID == latestReleaseID);
-				is_snapshot = false;
-			}
-			else if (versionTypeStr == "snapshot") // It's a snapshot... yay
-			{
-				is_latest = (versionID == latestSnapshotID);
-				is_snapshot = true;
-			}
-			else if (versionTypeStr == "old_alpha")
-			{
-				is_latest = false;
-				is_snapshot = false;
-			}
-			else if (versionTypeStr == "old_beta")
-			{
-				is_latest = false;
-				is_snapshot = false;
-			}
-			else
-			{
-				// FIXME: log this somewhere
-				continue;
-			}
-			mcVersion->m_type = versionTypeStr;
-			mcVersion->is_latest = is_latest;
-			mcVersion->is_snapshot = is_snapshot;
+			idx = i;
+			break;
 		}
-		tempList.append(mcVersion);
 	}
-	m_list->updateListData(tempList);
+	if (idx == -1)
+	{
+		return;
+	}
 
-	emitSucceeded();
-	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/minecraft/MinecraftVersionList.h b/logic/minecraft/MinecraftVersionList.h
index 18b9b21e..bbbd71e1 100644
--- a/logic/minecraft/MinecraftVersionList.h
+++ b/logic/minecraft/MinecraftVersionList.h
@@ -22,8 +22,10 @@
 #include "logic/BaseVersionList.h"
 #include "logic/tasks/Task.h"
 #include "logic/minecraft/MinecraftVersion.h"
+#include <logic/net/NetJob.h>
 
 class MCVListLoadTask;
+class MCVListVersionUpdateTask;
 class QNetworkReply;
 
 class MinecraftVersionList : public BaseVersionList
@@ -32,11 +34,18 @@ class MinecraftVersionList : public BaseVersionList
 private:
 	void sortInternal();
 	void loadBuiltinList();
+	void loadMojangList(QByteArray data, 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;
@@ -47,8 +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:
@@ -61,9 +74,9 @@ class MCVListLoadTask : public Task
 
 public:
 	explicit MCVListLoadTask(MinecraftVersionList *vlist);
-	~MCVListLoadTask();
+	virtual ~MCVListLoadTask() override{};
 
-	virtual void executeTask();
+	virtual void executeTask() override;
 
 protected
 slots:
@@ -74,3 +87,22 @@ protected:
 	MinecraftVersionList *m_list;
 	MinecraftVersion *m_currentStable;
 };
+
+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/minecraft/OneSixLibrary.cpp b/logic/minecraft/OneSixLibrary.cpp
index 45fa169e..7f69d9f8 100644
--- a/logic/minecraft/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/minecraft/OneSixLibrary.h b/logic/minecraft/OneSixLibrary.h
index 13df0606..3d38985b 100644
--- a/logic/minecraft/OneSixLibrary.h
+++ b/logic/minecraft/OneSixLibrary.h
@@ -24,27 +24,16 @@
 
 #include "logic/net/URLConstants.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;
-	/// type hint - modifies how the library is treated
-	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/minecraft/OneSixRule.h b/logic/minecraft/OneSixRule.h
index 23d04151..a18093b0 100644
--- a/logic/minecraft/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/minecraft/OneSixLibrary.h"
+class OneSixLibrary;
+class Rule;
 
 enum RuleAction
 {
diff --git a/logic/minecraft/ParseUtils.cpp b/logic/minecraft/ParseUtils.cpp
index 67460ca4..f94de6ff 100644
--- a/logic/minecraft/ParseUtils.cpp
+++ b/logic/minecraft/ParseUtils.cpp
@@ -8,16 +8,17 @@ QDateTime timeFromS3Time(QString str)
 	return QDateTime::fromString(str, Qt::ISODate);
 }
 
-void parse_timestamp (const QString & raw, QString & save_here, QDateTime & parse_here)
+bool parse_timestamp (const QString & raw, QString & save_here, QDateTime & parse_here)
 {
 	save_here = raw;
 	if (save_here.isEmpty())
 	{
-		throw JSONValidationError("The timestamp is empty!");
+		return false;
 	}
 	parse_here = timeFromS3Time(save_here);
 	if (!parse_here.isValid())
 	{
-		throw JSONValidationError("The timestamp not a valid timestamp!");
+		return false;
 	}
+	return true;
 }
diff --git a/logic/minecraft/ParseUtils.h b/logic/minecraft/ParseUtils.h
index 73cf526a..bd2f6ffb 100644
--- a/logic/minecraft/ParseUtils.h
+++ b/logic/minecraft/ParseUtils.h
@@ -6,7 +6,7 @@
  * parse the S3 timestamp in 'raw' and fill the forwarded variables.
  * return true/false for success/failure
  */
-void parse_timestamp (const QString &raw, QString &save_here, QDateTime &parse_here);
+bool parse_timestamp (const QString &raw, QString &save_here, QDateTime &parse_here);
 
 /**
  * take the timestamp used by S3 and turn it into QDateTime
diff --git a/logic/minecraft/RawLibrary.cpp b/logic/minecraft/RawLibrary.cpp
index 12aac8c8..7e0ebff0 100644
--- a/logic/minecraft/RawLibrary.cpp
+++ b/logic/minecraft/RawLibrary.cpp
@@ -11,7 +11,7 @@ RawLibraryPtr RawLibrary::fromJson(const QJsonObject &libObj, const QString &fil
 		throw JSONValidationError(filename +
 								  "contains a library that doesn't have a 'name' field");
 	}
-	out->name = libObj.value("name").toString();
+	out->m_name = libObj.value("name").toString();
 
 	auto readString = [libObj, filename](const QString & key, QString & variable)
 	{
@@ -29,22 +29,21 @@ RawLibraryPtr RawLibrary::fromJson(const QJsonObject &libObj, const QString &fil
 		}
 	};
 
-	readString("url", out->url);
-	readString("MMC-hint", out->hint);
-	readString("MMC-absulute_url", out->absoluteUrl);
-	readString("MMC-absoluteUrl", out->absoluteUrl);
+	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->excludes.append(ensureString(excludeVal));
+			out->extract_excludes.append(ensureString(excludeVal));
 		}
 	}
 	if (libObj.contains("natives"))
 	{
-		out->applyNatives = true;
 		QJsonObject nativesObj = ensureObject(libObj.value("natives"));
 		for (auto it = nativesObj.begin(); it != nativesObj.end(); ++it)
 		{
@@ -55,14 +54,152 @@ RawLibraryPtr RawLibrary::fromJson(const QJsonObject &libObj, const QString &fil
 			OpSys opSys = OpSys_fromString(it.key());
 			if (opSys != Os_Other)
 			{
-				out->natives.append(qMakePair(opSys, it.value().toString()));
+				out->m_native_suffixes[opSys] = it.value().toString();
 			}
 		}
 	}
 	if (libObj.contains("rules"))
 	{
 		out->applyRules = true;
-		out->rules = rulesFromJsonV4(libObj);
+		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
index 46178d8e..f5a28c61 100644
--- a/logic/minecraft/RawLibrary.h
+++ b/logic/minecraft/RawLibrary.h
@@ -1,9 +1,14 @@
 #pragma once
 #include <QString>
 #include <QPair>
+#include <QList>
+#include <QStringList>
+#include <QMap>
 #include <memory>
 
-#include "OneSixRule.h"
+#include "logic/minecraft/OneSixRule.h"
+#include "logic/minecraft/OpSys.h"
+#include "logic/net/URLConstants.h"
 
 class RawLibrary;
 typedef std::shared_ptr<RawLibrary> RawLibraryPtr;
@@ -11,24 +16,36 @@ 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 name;
-	QString url;
-	QString hint;
-	QString absoluteUrl;
+	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 excludes;
+	QStringList extract_excludes;
 
-	bool applyNatives = false;
-	QList<QPair<OpSys, QString>> natives;
+	/// 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>> rules;
+	QList<std::shared_ptr<Rule>> m_rules;
 
-	// user for '+' libraries
+	// used for '+' libraries
 	enum InsertType
 	{
 		Apply,
diff --git a/logic/minecraft/VersionBuilder.h b/logic/minecraft/VersionBuilder.h
index c56e6c18..fc06e614 100644
--- a/logic/minecraft/VersionBuilder.h
+++ b/logic/minecraft/VersionBuilder.h
@@ -30,7 +30,8 @@ class VersionBuilder
 public:
 	static void build(VersionFinal *version, OneSixInstance *instance, const QStringList &external);
 	static void readJsonAndApplyToVersion(VersionFinal *version, const QJsonObject &obj);
-
+	static VersionFilePtr parseJsonFile(const QFileInfo &fileInfo, const bool requireOrder, bool isFTB = false);
+	
 	static QMap<QString, int> readOverrideOrders(OneSixInstance *instance);
 	static bool writeOverrideOrders(const QMap<QString, int> &order, OneSixInstance *instance);
 
@@ -49,7 +50,4 @@ private:
 	void readInstancePatches();
 	
 	void readJsonAndApply(const QJsonObject &obj);
-
-	VersionFilePtr parseJsonFile(const QFileInfo &fileInfo, const bool requireOrder,
-							  bool isFTB = false);
 };
diff --git a/logic/minecraft/VersionFile.cpp b/logic/minecraft/VersionFile.cpp
index bc9c42c1..74e7ba98 100644
--- a/logic/minecraft/VersionFile.cpp
+++ b/logic/minecraft/VersionFile.cpp
@@ -98,14 +98,10 @@ VersionFilePtr VersionFile::fromJson(const QJsonDocument &doc, const QString &fi
 	readString("+minecraftArguments", out->addMinecraftArguments);
 	readString("-minecraftArguments", out->removeMinecraftArguments);
 	readString("type", out->type);
-	if (out->isVanilla())
-	{
-		parse_timestamp(readStringRet("releaseTime"), out->m_releaseTimeString,
-						out->m_releaseTime);
-		parse_timestamp(readStringRet("time"), out->m_updateTimeString, out->m_updateTime);
-	}
 
-	readStringRet("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"))
@@ -158,7 +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);
 			}
@@ -186,68 +182,8 @@ VersionFilePtr VersionFile::fromJson(const QJsonDocument &doc, const QString &fi
 		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);
 		}
 	}
@@ -263,32 +199,66 @@ 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;
 }
 
-bool VersionFile::isVanilla()
+bool VersionFile::isMinecraftVersion()
 {
-	return fileId == "org.multimc.version.json";
+	return (fileId == "org.multimc.version.json") || (fileId == "net.minecraft") ||
+		   (fileId == "org.multimc.custom.json");
 }
 
 bool VersionFile::hasJarMods()
@@ -330,13 +300,13 @@ void VersionFile::applyTo(VersionFinal *version)
 	}
 	if (!processArguments.isNull())
 	{
-		if (isVanilla())
+		if (isMinecraftVersion())
 		{
 			version->vanillaProcessArguments = processArguments;
 		}
 		version->processArguments = processArguments;
 	}
-	if(isVanilla())
+	if (isMinecraftVersion())
 	{
 		if (!type.isNull())
 		{
@@ -359,12 +329,12 @@ void VersionFile::applyTo(VersionFinal *version)
 	}
 	if (minimumLauncherVersion >= 0)
 	{
-		if(version->minimumLauncherVersion < minimumLauncherVersion)
+		if (version->minimumLauncherVersion < minimumLauncherVersion)
 			version->minimumLauncherVersion = minimumLauncherVersion;
 	}
 	if (!overwriteMinecraftArguments.isNull())
 	{
-		if (isVanilla())
+		if (isMinecraftVersion())
 		{
 			version->vanillaMinecraftArguments = overwriteMinecraftArguments;
 		}
@@ -397,10 +367,12 @@ void VersionFile::applyTo(VersionFinal *version)
 		QList<OneSixLibraryPtr> libs;
 		for (auto lib : overwriteLibs)
 		{
-			libs.append(createLibrary(lib));
+			libs.append(OneSixLibrary::fromRawLibrary(lib));
 		}
-		if (isVanilla())
+		if (isMinecraftVersion())
+		{
 			version->vanillaLibraries = libs;
+		}
 		version->libraries = libs;
 	}
 	for (auto lib : addLibs)
@@ -410,43 +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;
 		}
@@ -454,24 +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
@@ -485,7 +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
 					{
@@ -497,7 +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();
@@ -512,7 +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));
 						}
 					}
@@ -525,8 +500,8 @@ void VersionFile::applyTo(VersionFinal *version)
 			QString toReplace;
 			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;
@@ -534,7 +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
index 9c632d6f..2d3781cb 100644
--- a/logic/minecraft/VersionFile.h
+++ b/logic/minecraft/VersionFile.h
@@ -8,7 +8,7 @@
 #include "logic/minecraft/OneSixRule.h"
 #include "VersionPatch.h"
 #include "MMCError.h"
-#include "RawLibrary.h"
+#include "OneSixLibrary.h"
 #include "JarMod.h"
 
 class VersionFinal;
@@ -20,10 +20,10 @@ 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);
 
-	static OneSixLibraryPtr createLibrary(RawLibraryPtr lib);
 	virtual void applyTo(VersionFinal *version) override;
-	virtual bool isVanilla() override;
+	virtual bool isMinecraftVersion() override;
 	virtual bool hasJarMods() override;
 	virtual int getOrder() override
 	{
diff --git a/logic/minecraft/VersionPatch.h b/logic/minecraft/VersionPatch.h
index cdb80199..ef082b37 100644
--- a/logic/minecraft/VersionPatch.h
+++ b/logic/minecraft/VersionPatch.h
@@ -11,7 +11,7 @@ public:
 	virtual ~VersionPatch(){};
 	virtual void applyTo(VersionFinal *version) = 0;
 	
-	virtual bool isVanilla() = 0;
+	virtual bool isMinecraftVersion() = 0;
 	virtual bool hasJarMods() = 0;
 	virtual QList<JarmodPtr> getJarMods() = 0;
 	
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/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;
diff --git a/resources/versions/LWJGL/2.9.0.json b/resources/versions/LWJGL/2.9.0.json
index c2399878..5dbd624e 100644
--- a/resources/versions/LWJGL/2.9.0.json
+++ b/resources/versions/LWJGL/2.9.0.json
@@ -2,7 +2,7 @@
 	"fileId": "org.lwjgl",
 	"name": "LWJGL",
 	"version": "2.9.0",
-	"libraries": [
+	"+libraries": [
 		{
 			"name": "net.java.jinput:jinput:2.0.5"
 		},
diff --git a/resources/versions/LWJGL/2.9.1-nightly-20130708-debug3.json b/resources/versions/LWJGL/2.9.1-nightly-20130708-debug3.json
index f8ab7de5..7265b3b0 100644
--- a/resources/versions/LWJGL/2.9.1-nightly-20130708-debug3.json
+++ b/resources/versions/LWJGL/2.9.1-nightly-20130708-debug3.json
@@ -2,7 +2,7 @@
 	"fileId": "org.lwjgl",
 	"name": "LWJGL",
 	"version": "2.9.1-nightly-20130708-debug3",
-	"libraries": [
+	"+libraries": [
 		{
 			"name": "net.java.jinput:jinput:2.0.5"
 		},
diff --git a/resources/versions/LWJGL/2.9.1.json b/resources/versions/LWJGL/2.9.1.json
index 941cee1f..e7f5e947 100644
--- a/resources/versions/LWJGL/2.9.1.json
+++ b/resources/versions/LWJGL/2.9.1.json
@@ -2,7 +2,7 @@
 	"fileId": "org.lwjgl",
 	"name": "LWJGL",
 	"version": "2.9.1",
-	"libraries": [
+	"+libraries": [
 		{
 			"name": "net.java.jinput:jinput:2.0.5"
 		},