Merge branch 'develop' into feature_badges

Conflicts:
	logic/OneSixInstance.cpp

27 files changed, 1420 insertions, 1441 deletions

diff --git a/logic/BaseInstaller.cpp b/logic/BaseInstaller.cpp
index 92aa0c92..669fd0ac 100644
--- a/logic/BaseInstaller.cpp
+++ b/logic/BaseInstaller.cpp
@@ -17,7 +17,7 @@
 
 #include <QFile>
 
-#include "OneSixVersion.h"
+#include "VersionFinal.h"
 #include "OneSixLibrary.h"
 #include "OneSixInstance.h"
 
diff --git a/logic/BaseInstance.cpp b/logic/BaseInstance.cpp
index 24af20cf..c7b29548 100644
--- a/logic/BaseInstance.cpp
+++ b/logic/BaseInstance.cpp
@@ -168,6 +168,11 @@ bool BaseInstance::canLaunch() const
 	return !flags().contains(VersionBrokenFlag);
 }
 
+bool BaseInstance::reload()
+{
+	return settings().reload();
+}
+
 QString BaseInstance::baseJar() const
 {
 	I_D(BaseInstance);
diff --git a/logic/BaseInstance.h b/logic/BaseInstance.h
index 443b0eaa..d38ae409 100644
--- a/logic/BaseInstance.h
+++ b/logic/BaseInstance.h
@@ -190,6 +190,8 @@ public:
 
 	bool canLaunch() const;
 
+	virtual bool reload();
+
 signals:
 	/*!
 	 * \brief Signal emitted when properties relevant to the instance view change
diff --git a/logic/ForgeInstaller.cpp b/logic/ForgeInstaller.cpp
index 3e18d17f..6f238c21 100644
--- a/logic/ForgeInstaller.cpp
+++ b/logic/ForgeInstaller.cpp
@@ -14,7 +14,7 @@
  */
 
 #include "ForgeInstaller.h"
-#include "OneSixVersion.h"
+#include "VersionFinal.h"
 #include "OneSixLibrary.h"
 #include "net/HttpMetaCache.h"
 #include <quazip.h>
@@ -33,7 +33,7 @@
 
 ForgeInstaller::ForgeInstaller(QString filename, QString universal_url)
 {
-	std::shared_ptr<OneSixVersion> newVersion;
+	std::shared_ptr<VersionFinal> newVersion;
 	m_universal_url = universal_url;
 
 	QuaZip zip(filename);
@@ -66,7 +66,7 @@ ForgeInstaller::ForgeInstaller(QString filename, QString universal_url)
 
 	// read the forge version info
 	{
-		newVersion = OneSixVersion::fromJson(versionInfoVal.toObject());
+		newVersion = VersionFinal::fromJson(versionInfoVal.toObject());
 		if (!newVersion)
 			return;
 	}
diff --git a/logic/ForgeInstaller.h b/logic/ForgeInstaller.h
index c5052092..df029f38 100644
--- a/logic/ForgeInstaller.h
+++ b/logic/ForgeInstaller.h
@@ -20,7 +20,7 @@
 #include <QString>
 #include <memory>
 
-class OneSixVersion;
+class VersionFinal;
 
 class ForgeInstaller : public BaseInstaller
 {
@@ -33,7 +33,7 @@ public:
 
 private:
 	// the version, read from the installer
-	std::shared_ptr<OneSixVersion> m_forge_version;
+	std::shared_ptr<VersionFinal> m_forge_version;
 	QString internalPath;
 	QString finalPath;
 	QString realVersionId;
diff --git a/logic/LiteLoaderInstaller.cpp b/logic/LiteLoaderInstaller.cpp
index 126027fb..bb4b07ca 100644
--- a/logic/LiteLoaderInstaller.cpp
+++ b/logic/LiteLoaderInstaller.cpp
@@ -20,7 +20,7 @@
 
 #include "logger/QsLog.h"
 
-#include "OneSixVersion.h"
+#include "VersionFinal.h"
 #include "OneSixLibrary.h"
 #include "OneSixInstance.h"
 
@@ -69,7 +69,7 @@ bool LiteLoaderInstaller::add(OneSixInstance *to)
 	obj.insert("+libraries", libraries);
 	obj.insert("name", QString("LiteLoader"));
 	obj.insert("fileId", id());
-	obj.insert("version", to->intendedVersionId());
+	obj.insert("version", m_version->version);
 	obj.insert("mcVersion", to->intendedVersionId());
 
 	QFile file(filename(to->instanceRoot()));
diff --git a/logic/MMCJson.cpp b/logic/MMCJson.cpp
new file mode 100644
index 00000000..25cc2de3
--- /dev/null
+++ b/logic/MMCJson.cpp
@@ -0,0 +1,61 @@
+#include "MMCJson.h"
+#include <QString>
+#include <math.h>
+
+bool MMCJson::ensureBoolean(const QJsonValue val, const QString what)
+{
+	if (!val.isBool())
+		throw JSONValidationError(what + " is not boolean");
+	return val.isBool();
+}
+
+QJsonValue MMCJson::ensureExists(QJsonValue val, const QString what)
+{
+	if(val.isNull())
+		throw JSONValidationError(what + " does not exist");
+	return val;
+}
+
+QJsonArray MMCJson::ensureArray(const QJsonValue val, const QString what)
+{
+	if (!val.isArray())
+		throw JSONValidationError(what + " is not an array");
+	return val.toArray();
+}
+
+double MMCJson::ensureDouble(const QJsonValue val, const QString what)
+{
+	if (!val.isDouble())
+		throw JSONValidationError(what + " is not a number");
+	double ret = val.toDouble();
+}
+
+int MMCJson::ensureInteger(const QJsonValue val, const QString what)
+{
+	double ret = ensureDouble(val, what);
+	if (fmod(ret, 1) != 0)
+		throw JSONValidationError(what + " is not an integer");
+	return ret;
+}
+
+QJsonObject MMCJson::ensureObject(const QJsonValue val, const QString what)
+{
+	if (!val.isObject())
+		throw JSONValidationError(what + " is not an object");
+	return val.toObject();
+}
+
+QJsonObject MMCJson::ensureObject(const QJsonDocument val, const QString what)
+{
+	if (!val.isObject())
+		throw JSONValidationError(what + " is not an object");
+	return val.object();
+}
+
+QString MMCJson::ensureString(const QJsonValue val, const QString what)
+{
+	if (!val.isString())
+		throw JSONValidationError(what + " is not a string");
+	return val.toString();
+}
+
diff --git a/logic/MMCJson.h b/logic/MMCJson.h
new file mode 100644
index 00000000..71ded435
--- /dev/null
+++ b/logic/MMCJson.h
@@ -0,0 +1,46 @@
+/**
+ * Some de-bullshitting for Qt JSON failures.
+ *
+ * Simple exception-throwing
+ */
+
+#pragma once
+#include <QJsonValue>
+#include <QJsonObject>
+#include <QJsonDocument>
+#include <QJsonArray>
+#include "MMCError.h"
+
+class JSONValidationError : public MMCError
+{
+public:
+	JSONValidationError(QString cause) : MMCError(cause) {};
+	virtual ~JSONValidationError() noexcept {}
+};
+
+namespace MMCJson
+{
+/// make sure the value exists. throw otherwise.
+QJsonValue ensureExists(QJsonValue val, const QString what = "value");
+
+/// make sure the value is converted into an object. throw otherwise.
+QJsonObject ensureObject(const QJsonValue val, const QString what = "value");
+
+/// make sure the document is converted into an object. throw otherwise.
+QJsonObject ensureObject(const QJsonDocument val, const QString what = "value");
+
+/// make sure the value is converted into an array. throw otherwise.
+QJsonArray ensureArray(const QJsonValue val, QString what = "value");
+
+/// make sure the value is converted into a string. throw otherwise.
+QString ensureString(const QJsonValue val, QString what = "value");
+
+/// make sure the value is converted into a boolean. throw otherwise.
+bool ensureBoolean(const QJsonValue val, QString what = "value");
+
+/// make sure the value is converted into an integer. throw otherwise.
+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");
+}
diff --git a/logic/MinecraftProcess.cpp b/logic/MinecraftProcess.cpp
index 89cd71ed..effa1095 100644
--- a/logic/MinecraftProcess.cpp
+++ b/logic/MinecraftProcess.cpp
@@ -49,9 +49,11 @@ MinecraftProcess::MinecraftProcess(BaseInstance *inst) : m_instance(inst)
 #endif
 
 	// export some infos
-	env.insert("INST_NAME", inst->name());
-	env.insert("INST_ID", inst->id());
-	env.insert("INST_DIR", QDir(inst->instanceRoot()).absolutePath());
+	auto variables = getVariables();
+	for (auto it = variables.begin(); it != variables.end(); ++it)
+	{
+		env.insert(it.key(), it.value());
+	}
 
 	this->setProcessEnvironment(env);
 	m_prepostlaunchprocess.setProcessEnvironment(env);
@@ -63,10 +65,10 @@ MinecraftProcess::MinecraftProcess(BaseInstance *inst) : m_instance(inst)
 	// Log prepost launch command output (can be disabled.)
 	if (m_instance->settings().get("LogPrePostOutput").toBool())
 	{
-		connect(&m_prepostlaunchprocess, &QProcess::readyReadStandardError,
-				this, &MinecraftProcess::on_prepost_stdErr);
-		connect(&m_prepostlaunchprocess, &QProcess::readyReadStandardOutput,
-				this, &MinecraftProcess::on_prepost_stdOut);
+		connect(&m_prepostlaunchprocess, &QProcess::readyReadStandardError, this,
+				&MinecraftProcess::on_prepost_stdErr);
+		connect(&m_prepostlaunchprocess, &QProcess::readyReadStandardOutput, this,
+				&MinecraftProcess::on_prepost_stdOut);
 	}
 }
 
@@ -79,10 +81,10 @@ void MinecraftProcess::setWorkdir(QString path)
 
 QString MinecraftProcess::censorPrivateInfo(QString in)
 {
-	if(!m_session)
+	if (!m_session)
 		return in;
 
-	if(m_session->session != "-")
+	if (m_session->session != "-")
 		in.replace(m_session->session, "<SESSION ID>");
 	in.replace(m_session->access_token, "<ACCESS TOKEN>");
 	in.replace(m_session->client_token, "<CLIENT TOKEN>");
@@ -113,7 +115,7 @@ MessageLevel::Enum MinecraftProcess::guessLevel(const QString &line, MessageLeve
 		level = MessageLevel::Fatal;
 	if (line.contains("[DEBUG]"))
 		level = MessageLevel::Debug;
-	if(line.contains("overwriting existing"))
+	if (line.contains("overwriting existing"))
 		level = MessageLevel::Fatal;
 	return level;
 }
@@ -139,17 +141,15 @@ MessageLevel::Enum MinecraftProcess::getLevel(const QString &levelName)
 		return MessageLevel::Message;
 }
 
-void MinecraftProcess::logOutput(const QStringList &lines,
-								 MessageLevel::Enum defaultLevel,
+void MinecraftProcess::logOutput(const QStringList &lines, MessageLevel::Enum defaultLevel,
 								 bool guessLevel, bool censor)
 {
 	for (int i = 0; i < lines.size(); ++i)
 		logOutput(lines[i], defaultLevel, guessLevel, censor);
 }
 
-void MinecraftProcess::logOutput(QString line,
-								 MessageLevel::Enum defaultLevel,
-								 bool guessLevel, bool censor)
+void MinecraftProcess::logOutput(QString line, MessageLevel::Enum defaultLevel, bool guessLevel,
+								 bool censor)
 {
 	MessageLevel::Enum level = defaultLevel;
 
@@ -251,33 +251,7 @@ void MinecraftProcess::finish(int code, ExitStatus status)
 	m_prepostlaunchprocess.processEnvironment().insert("INST_EXITCODE", QString(code));
 
 	// run post-exit
-	QString postlaunch_cmd = m_instance->settings().get("PostExitCommand").toString();
-	if (!postlaunch_cmd.isEmpty())
-	{
-		emit log(tr("Running Post-Launch command: %1").arg(postlaunch_cmd));
-		m_prepostlaunchprocess.start(postlaunch_cmd);
-		m_prepostlaunchprocess.waitForFinished();
-		// Flush console window
-		if (!m_err_leftover.isEmpty())
-		{
-			logOutput(m_err_leftover, MessageLevel::PrePost);
-			m_err_leftover.clear();
-		}
-		if (!m_out_leftover.isEmpty())
-		{
-			logOutput(m_out_leftover, MessageLevel::PrePost);
-			m_out_leftover.clear();
-		}
-		if (m_prepostlaunchprocess.exitStatus() != NormalExit)
-		{
-			emit log(tr("Post-Launch command failed with code %1.\n\n").arg(m_prepostlaunchprocess.exitCode()),
-					 MessageLevel::Error);
-			emit postlaunch_failed(m_instance, m_prepostlaunchprocess.exitCode(),
-								   m_prepostlaunchprocess.exitStatus());
-		}
-		else
-			emit log(tr("Post-Launch command ran successfully.\n\n"));
-	}
+	postLaunch();
 	m_instance->cleanupAfterRun();
 	emit ended(m_instance, code, status);
 }
@@ -288,14 +262,12 @@ void MinecraftProcess::killMinecraft()
 	kill();
 }
 
-void MinecraftProcess::arm()
+bool MinecraftProcess::preLaunch()
 {
-	emit log("MultiMC version: " + MMC->version().toString() + "\n\n");
-	emit log("Minecraft folder is:\n" + workingDirectory() + "\n\n");
-
 	QString prelaunch_cmd = m_instance->settings().get("PreLaunchCommand").toString();
 	if (!prelaunch_cmd.isEmpty())
 	{
+		prelaunch_cmd = substituteVariables(prelaunch_cmd);
 		// Launch
 		emit log(tr("Running Pre-Launch command: %1").arg(prelaunch_cmd));
 		m_prepostlaunchprocess.start(prelaunch_cmd);
@@ -315,46 +287,129 @@ void MinecraftProcess::arm()
 		// Process return values
 		if (m_prepostlaunchprocess.exitStatus() != NormalExit)
 		{
-			emit log(tr("Pre-Launch command failed with code %1.\n\n").arg(m_prepostlaunchprocess.exitCode()),
+			emit log(tr("Pre-Launch command failed with code %1.\n\n")
+						 .arg(m_prepostlaunchprocess.exitCode()),
 					 MessageLevel::Fatal);
 			m_instance->cleanupAfterRun();
 			emit prelaunch_failed(m_instance, m_prepostlaunchprocess.exitCode(),
 								  m_prepostlaunchprocess.exitStatus());
-			return;
+			return false;
 		}
 		else
 			emit log(tr("Pre-Launch command ran successfully.\n\n"));
+
+		return m_instance->reload();
+	}
+	return true;
+}
+bool MinecraftProcess::postLaunch()
+{
+	QString postlaunch_cmd = m_instance->settings().get("PostExitCommand").toString();
+	if (!postlaunch_cmd.isEmpty())
+	{
+		postlaunch_cmd = substituteVariables(postlaunch_cmd);
+		emit log(tr("Running Post-Launch command: %1").arg(postlaunch_cmd));
+		m_prepostlaunchprocess.start(postlaunch_cmd);
+		m_prepostlaunchprocess.waitForFinished();
+		// Flush console window
+		if (!m_err_leftover.isEmpty())
+		{
+			logOutput(m_err_leftover, MessageLevel::PrePost);
+			m_err_leftover.clear();
+		}
+		if (!m_out_leftover.isEmpty())
+		{
+			logOutput(m_out_leftover, MessageLevel::PrePost);
+			m_out_leftover.clear();
+		}
+		if (m_prepostlaunchprocess.exitStatus() != NormalExit)
+		{
+			emit log(tr("Post-Launch command failed with code %1.\n\n")
+						 .arg(m_prepostlaunchprocess.exitCode()),
+					 MessageLevel::Error);
+			emit postlaunch_failed(m_instance, m_prepostlaunchprocess.exitCode(),
+								   m_prepostlaunchprocess.exitStatus());
+		}
+		else
+			emit log(tr("Post-Launch command ran successfully.\n\n"));
+
+		return m_instance->reload();
 	}
+	return true;
+}
 
-	m_instance->setLastLaunch();
-	auto &settings = m_instance->settings();
+QMap<QString, QString> MinecraftProcess::getVariables() const
+{
+	QMap<QString, QString> out;
+	out.insert("INST_NAME", m_instance->name());
+	out.insert("INST_ID", m_instance->id());
+	out.insert("INST_DIR", QDir(m_instance->instanceRoot()).absolutePath());
+	out.insert("INST_MC_DIR", QDir(m_instance->minecraftRoot()).absolutePath());
+	out.insert("INST_JAVA", m_instance->settings().get("JavaPath").toString());
+	out.insert("INST_JAVA_ARGS", javaArguments().join(' '));
+	return out;
+}
+QString MinecraftProcess::substituteVariables(const QString &cmd) const
+{
+	QString out = cmd;
+	auto variables = getVariables();
+	for (auto it = variables.begin(); it != variables.end(); ++it)
+	{
+		out.replace("$" + it.key(), it.value());
+	}
+	auto env = QProcessEnvironment::systemEnvironment();
+	for (auto var : env.keys())
+	{
+		out.replace("$" + var, env.value(var));
+	}
+	return out;
+}
 
-	//////////// java arguments ////////////
+QStringList MinecraftProcess::javaArguments() const
+{
 	QStringList args;
+
+	// custom args go first. we want to override them if we have our own here.
+	args.append(m_instance->extraArguments());
+
+// OSX dock icon and name
+#ifdef OSX
+	args << "-Xdock:icon=icon.png";
+	args << QString("-Xdock:name=\"%1\"").arg(m_instance->windowTitle());
+#endif
+
+// HACK: Stupid hack for Intel drivers. See: https://mojang.atlassian.net/browse/MCL-767
+#ifdef Q_OS_WIN32
+	args << QString("-XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_"
+					"minecraft.exe.heapdump");
+#endif
+
+	args << QString("-Xms%1m").arg(m_instance->settings().get("MinMemAlloc").toInt());
+	args << QString("-Xmx%1m").arg(m_instance->settings().get("MaxMemAlloc").toInt());
+	args << QString("-XX:PermSize=%1m").arg(m_instance->settings().get("PermGen").toInt());
+	args << "-Duser.language=en";
+	if (!m_nativeFolder.isEmpty())
+		args << QString("-Djava.library.path=%1").arg(m_nativeFolder);
+	args << "-jar" << PathCombine(MMC->bin(), "jars", "NewLaunch.jar");
+
+	return args;
+}
+
+void MinecraftProcess::arm()
+{
+	emit log("MultiMC version: " + MMC->version().toString() + "\n\n");
+	emit log("Minecraft folder is:\n" + workingDirectory() + "\n\n");
+
+	if (!preLaunch())
 	{
-		// custom args go first. we want to override them if we have our own here.
-		args.append(m_instance->extraArguments());
-
-		// OSX dock icon and name
-		#ifdef OSX
-		args << "-Xdock:icon=icon.png";
-		args << QString("-Xdock:name=\"%1\"").arg(m_instance->windowTitle());
-		#endif
-
-		// HACK: Stupid hack for Intel drivers. See: https://mojang.atlassian.net/browse/MCL-767
-		#ifdef Q_OS_WIN32
-		args << QString("-XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_"
-						"minecraft.exe.heapdump");
-		#endif
-
-		args << QString("-Xms%1m").arg(settings.get("MinMemAlloc").toInt());
-		args << QString("-Xmx%1m").arg(settings.get("MaxMemAlloc").toInt());
-		args << QString("-XX:PermSize=%1m").arg(settings.get("PermGen").toInt());
-		if(!m_nativeFolder.isEmpty())
-			args << QString("-Djava.library.path=%1").arg(m_nativeFolder);
-		args << "-jar" << PathCombine(MMC->bin(), "jars", "NewLaunch.jar");
+		return;
 	}
 
+	m_instance->setLastLaunch();
+	auto &settings = m_instance->settings();
+
+	QStringList args = javaArguments();
+
 	QString JavaPath = m_instance->settings().get("JavaPath").toString();
 	emit log("Java path is:\n" + JavaPath + "\n\n");
 	QString allArgs = args.join(", ");
diff --git a/logic/MinecraftProcess.h b/logic/MinecraftProcess.h
index 56340962..d91dad56 100644
--- a/logic/MinecraftProcess.h
+++ b/logic/MinecraftProcess.h
@@ -131,6 +131,13 @@ protected:
 	QString launchScript;
 	QString m_nativeFolder;
 
+	bool preLaunch();
+	bool postLaunch();
+	QMap<QString, QString> getVariables() const;
+	QString substituteVariables(const QString &cmd) const;
+
+	QStringList javaArguments() const;
+
 protected
 slots:
 	void finish(int, QProcess::ExitStatus status);
diff --git a/logic/OneSixFTBInstance.cpp b/logic/OneSixFTBInstance.cpp
index 07b123b6..172830bb 100644
--- a/logic/OneSixFTBInstance.cpp
+++ b/logic/OneSixFTBInstance.cpp
@@ -1,6 +1,6 @@
 #include "OneSixFTBInstance.h"
 
-#include "OneSixVersion.h"
+#include "VersionFinal.h"
 #include "OneSixLibrary.h"
 #include "tasks/SequentialTask.h"
 #include "ForgeInstaller.h"
@@ -10,76 +10,6 @@
 #include "MultiMC.h"
 #include "pathutils.h"
 
-class OneSixFTBInstanceForge : public Task
-{
-	Q_OBJECT
-public:
-	explicit OneSixFTBInstanceForge(const QString &version, OneSixFTBInstance *inst, QObject *parent = 0) :
-		Task(parent), instance(inst), version("Forge " + version)
-	{
-	}
-
-	void executeTask()
-	{
-		for (int i = 0; i < MMC->forgelist()->count(); ++i)
-		{
-			if (MMC->forgelist()->at(i)->name() == version)
-			{
-				forgeVersion = std::dynamic_pointer_cast<ForgeVersion>(MMC->forgelist()->at(i));
-				break;
-			}
-		}
-		if (!forgeVersion)
-		{
-			emitFailed(QString("Couldn't find forge version ") + version );
-			return;
-		}
-		entry = MMC->metacache()->resolveEntry("minecraftforge", forgeVersion->filename);
-		if (entry->stale)
-		{
-			setStatus(tr("Downloading Forge..."));
-			fjob = new NetJob("Forge download");
-			fjob->addNetAction(CacheDownload::make(forgeVersion->installer_url, entry));
-			connect(fjob, &NetJob::failed, [this](){emitFailed(m_failReason);});
-			connect(fjob, &NetJob::succeeded, this, &OneSixFTBInstanceForge::installForge);
-			connect(fjob, &NetJob::progress, [this](qint64 c, qint64 total){ setProgress(100 * c / total); });
-			fjob->start();
-		}
-		else
-		{
-			installForge();
-		}
-	}
-
-private
-slots:
-	void installForge()
-	{
-		setStatus(tr("Installing Forge..."));
-		QString forgePath = entry->getFullPath();
-		ForgeInstaller forge(forgePath, forgeVersion->universal_url);
-		if (!instance->reloadVersion())
-		{
-			emitFailed(tr("Couldn't load the version config"));
-			return;
-		}
-		auto version = instance->getFullVersion();
-		if (!forge.add(instance))
-		{
-			emitFailed(tr("Couldn't install Forge"));
-			return;
-		}
-		emitSucceeded();
-	}
-
-private:
-	OneSixFTBInstance *instance;
-	QString version;
-	ForgeVersionPtr forgeVersion;
-	MetaEntryPtr entry;
-	NetJob *fjob;
-};
-
 OneSixFTBInstance::OneSixFTBInstance(const QString &rootDir, SettingsObject *settings, QObject *parent) :
 	OneSixInstance(rootDir, settings, parent)
 {
@@ -87,7 +17,14 @@ OneSixFTBInstance::OneSixFTBInstance(const QString &rootDir, SettingsObject *set
 
 void OneSixFTBInstance::init()
 {
-	reloadVersion();
+	try
+	{
+		reloadVersion();
+	}
+	catch(MMCError & e)
+	{
+		// QLOG_ERROR() << "Caught exception on instance init: " << e.cause();
+	}
 }
 
 void OneSixFTBInstance::copy(const QDir &newDir)
diff --git a/logic/OneSixInstance.cpp b/logic/OneSixInstance.cpp
index 148fbc09..ccc25845 100644
--- a/logic/OneSixInstance.cpp
+++ b/logic/OneSixInstance.cpp
@@ -19,7 +19,7 @@
 
 #include "OneSixInstance_p.h"
 #include "OneSixUpdate.h"
-#include "OneSixVersion.h"
+#include "VersionFinal.h"
 #include "pathutils.h"
 #include "logger/QsLog.h"
 #include "assets/AssetsUtils.h"
@@ -27,6 +27,7 @@
 #include "icons/IconList.h"
 #include "MinecraftProcess.h"
 #include "gui/dialogs/OneSixModEditDialog.h"
+#include <MMCError.h>
 
 OneSixInstance::OneSixInstance(const QString &rootDir, SettingsObject *settings, QObject *parent)
 	: BaseInstance(new OneSixInstancePrivate(), rootDir, settings, parent)
@@ -34,15 +35,23 @@ OneSixInstance::OneSixInstance(const QString &rootDir, SettingsObject *settings,
 	I_D(OneSixInstance);
 	d->m_settings->registerSetting("IntendedVersion", "");
 	d->m_settings->registerSetting("ShouldUpdate", false);
-	d->version.reset(new OneSixVersion(this, this));
-	d->vanillaVersion.reset(new OneSixVersion(this, this));
+	d->version.reset(new VersionFinal(this, this));
+	d->vanillaVersion.reset(new VersionFinal(this, this));
 }
 
 void OneSixInstance::init()
 {
+	// FIXME: why is this decided here? what does this even mean?
 	if (QDir(instanceRoot()).exists("version.json"))
 	{
-		reloadVersion();
+		try
+		{
+			reloadVersion();
+		}
+		catch(MMCError & e)
+		{
+			// QLOG_ERROR() << "Caught exception on instance init: " << e.cause();
+		}
 	}
 	else
 	{
@@ -79,7 +88,7 @@ QString replaceTokensIn(QString text, QMap<QString, QString> with)
 	return result;
 }
 
-QDir OneSixInstance::reconstructAssets(std::shared_ptr<OneSixVersion> version)
+QDir OneSixInstance::reconstructAssets(std::shared_ptr<VersionFinal> version)
 {
 	QDir assetsDir = QDir("assets/");
 	QDir indexDir = QDir(PathCombine(assetsDir.path(), "indexes"));
@@ -316,25 +325,26 @@ QString OneSixInstance::currentVersionId() const
 	return intendedVersionId();
 }
 
-bool OneSixInstance::reloadVersion(QWidget *widgetParent)
+void OneSixInstance::reloadVersion()
 {
 	I_D(OneSixInstance);
 
-	bool ret = d->version->reload(widgetParent, false, externalPatches());
-	if (ret)
-	{
-		ret = d->vanillaVersion->reload(widgetParent, true, externalPatches());
-	}
-	if (ret)
+	try
 	{
+		d->version->reload(false, externalPatches());
+		d->vanillaVersion->reload(true, externalPatches());
 		d->m_flags.remove(VersionBrokenFlag);
 		emit versionReloaded();
 	}
-	else
+	catch(MMCError & error)
 	{
+		d->version->clear();
+		d->vanillaVersion->clear();
 		d->m_flags.insert(VersionBrokenFlag);
+		//TODO: rethrow to show some error message(s)?
+		emit versionReloaded();
+		throw;
 	}
-	return ret;
 }
 
 void OneSixInstance::clearVersion()
@@ -345,13 +355,13 @@ void OneSixInstance::clearVersion()
 	emit versionReloaded();
 }
 
-std::shared_ptr<OneSixVersion> OneSixInstance::getFullVersion() const
+std::shared_ptr<VersionFinal> OneSixInstance::getFullVersion() const
 {
 	I_D(const OneSixInstance);
 	return d->version;
 }
 
-std::shared_ptr<OneSixVersion> OneSixInstance::getVanillaVersion() const
+std::shared_ptr<VersionFinal> OneSixInstance::getVanillaVersion() const
 {
 	I_D(const OneSixInstance);
 	return d->vanillaVersion;
@@ -413,6 +423,23 @@ bool OneSixInstance::providesVersionFile() const
 	return false;
 }
 
+bool OneSixInstance::reload()
+{
+	if(BaseInstance::reload())
+	{
+		try
+		{
+			reloadVersion();
+			return true;
+		}
+		catch (...)
+		{
+			return false;
+		}
+	}
+	return false;
+}
+
 QString OneSixInstance::loaderModsDir() const
 {
 	return PathCombine(minecraftRoot(), "mods");
diff --git a/logic/OneSixInstance.h b/logic/OneSixInstance.h
index 06fd9de3..7a049922 100644
--- a/logic/OneSixInstance.h
+++ b/logic/OneSixInstance.h
@@ -17,7 +17,7 @@
 
 #include "BaseInstance.h"
 
-#include "OneSixVersion.h"
+#include "VersionFinal.h"
 #include "ModList.h"
 
 class OneSixInstance : public BaseInstance
@@ -53,14 +53,18 @@ public:
 
 	virtual QDialog *createModEditDialog(QWidget *parent) override;
 
-	/// reload the full version json files. return true on success!
-	bool reloadVersion(QWidget *widgetParent = 0);
+	/**
+	 * reload the full version json files. return true on success!
+	 * 
+	 * 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<OneSixVersion> getFullVersion() const;
+	std::shared_ptr<VersionFinal> getFullVersion() const;
 	/// gets the current version info, but only for version.json
-	std::shared_ptr<OneSixVersion> getVanillaVersion() const;
+	std::shared_ptr<VersionFinal> getVanillaVersion() const;
 	/// is the current version original, or custom?
 	virtual bool versionIsCustom() override;
 
@@ -75,10 +79,12 @@ public:
 	virtual QStringList externalPatches() const;
 	virtual bool providesVersionFile() const;
 
+	bool reload() override;
+
 signals:
 	void versionReloaded();
 
 private:
 	QStringList processMinecraftArgs(AuthSessionPtr account);
-	QDir reconstructAssets(std::shared_ptr<OneSixVersion> version);
+	QDir reconstructAssets(std::shared_ptr<VersionFinal> version);
 };
diff --git a/logic/OneSixInstance_p.h b/logic/OneSixInstance_p.h
index 0cc46f33..2dffa62c 100644
--- a/logic/OneSixInstance_p.h
+++ b/logic/OneSixInstance_p.h
@@ -16,13 +16,13 @@
 #pragma once
 
 #include "BaseInstance_p.h"
-#include "OneSixVersion.h"
+#include "VersionFinal.h"
 #include "ModList.h"
 
 struct OneSixInstancePrivate : public BaseInstancePrivate
 {
-	std::shared_ptr<OneSixVersion> version;
-	std::shared_ptr<OneSixVersion> vanillaVersion;
+	std::shared_ptr<VersionFinal> version;
+	std::shared_ptr<VersionFinal> vanillaVersion;
 	std::shared_ptr<ModList> loader_mod_list;
 	std::shared_ptr<ModList> resource_pack_list;
 };
diff --git a/logic/OneSixLibrary.h b/logic/OneSixLibrary.h
index 371ca6f4..3bd21c51 100644
--- a/logic/OneSixLibrary.h
+++ b/logic/OneSixLibrary.h
@@ -26,6 +26,9 @@
 
 class Rule;
 
+class OneSixLibrary;
+typedef std::shared_ptr<OneSixLibrary> OneSixLibraryPtr;
+
 class OneSixLibrary
 {
 private:
diff --git a/logic/OneSixUpdate.cpp b/logic/OneSixUpdate.cpp
index f87c65e7..65f30cda 100644
--- a/logic/OneSixUpdate.cpp
+++ b/logic/OneSixUpdate.cpp
@@ -25,7 +25,7 @@
 
 #include "BaseInstance.h"
 #include "lists/MinecraftVersionList.h"
-#include "OneSixVersion.h"
+#include "VersionFinal.h"
 #include "OneSixLibrary.h"
 #include "OneSixInstance.h"
 #include "net/ForgeMirrors.h"
@@ -48,7 +48,7 @@ void OneSixUpdate::executeTask()
 	QDir mcDir(m_inst->minecraftRoot());
 	if (!mcDir.exists() && !mcDir.mkpath("."))
 	{
-		emitFailed("Failed to create bin folder.");
+		emitFailed(tr("Failed to create folder for minecraft binaries."));
 		return;
 	}
 
@@ -60,7 +60,7 @@ void OneSixUpdate::executeTask()
 		if (targetVersion == nullptr)
 		{
 			// don't do anything if it was invalid
-			emitFailed("The specified Minecraft version is invalid. Choose a different one.");
+			emitFailed(tr("The specified Minecraft version is invalid. Choose a different one."));
 			return;
 		}
 		versionFileStart();
@@ -108,20 +108,19 @@ void OneSixUpdate::versionFileFinished()
 		QSaveFile vfile1(version1);
 		if (!vfile1.open(QIODevice::Truncate | QIODevice::WriteOnly))
 		{
-			emitFailed("Can't open " + version1 + " for writing.");
+			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("Failed to write into " + version1 + ". Written " + actual + " out of " +
-					   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("Can't commit changes to " + version1);
+			emitFailed(tr("Can't commit changes to %1").arg(version1));
 			return;
 		}
 	}
@@ -136,21 +135,20 @@ void OneSixUpdate::versionFileFinished()
 	{
 		finfo.remove();
 	}
-	inst->reloadVersion();
-
+	// NOTE: Version is reloaded in jarlibStart
 	jarlibStart();
 }
 
 void OneSixUpdate::versionFileFailed()
 {
-	emitFailed("Failed to download the version description. Try again.");
+	emitFailed(tr("Failed to download the version description. Try again."));
 }
 
 void OneSixUpdate::assetIndexStart()
 {
 	setStatus(tr("Updating assets index..."));
 	OneSixInstance *inst = (OneSixInstance *)m_inst;
-	std::shared_ptr<OneSixVersion> version = inst->getFullVersion();
+	std::shared_ptr<VersionFinal> version = inst->getFullVersion();
 	QString assetName = version->assets;
 	QUrl indexUrl = "http://" + URLConstants::AWS_DOWNLOAD_INDEXES + assetName + ".json";
 	QString localPath = assetName + ".json";
@@ -174,13 +172,13 @@ void OneSixUpdate::assetIndexFinished()
 	AssetsIndex index;
 
 	OneSixInstance *inst = (OneSixInstance *)m_inst;
-	std::shared_ptr<OneSixVersion> version = inst->getFullVersion();
+	std::shared_ptr<VersionFinal> version = inst->getFullVersion();
 	QString assetName = version->assets;
 
 	QString asset_fname = "assets/indexes/" + assetName + ".json";
 	if (!AssetsUtils::loadAssetsIndexJson(asset_fname, &index))
 	{
-		emitFailed("Failed to read the assets index!");
+		emitFailed(tr("Failed to read the assets index!"));
 	}
 
 	QList<Md5EtagDownloadPtr> dls;
@@ -216,7 +214,7 @@ void OneSixUpdate::assetIndexFinished()
 
 void OneSixUpdate::assetIndexFailed()
 {
-	emitFailed("Failed to download the assets index!");
+	emitFailed(tr("Failed to download the assets index!"));
 }
 
 void OneSixUpdate::assetsFinished()
@@ -226,7 +224,7 @@ void OneSixUpdate::assetsFinished()
 
 void OneSixUpdate::assetsFailed()
 {
-	emitFailed("Failed to download assets!");
+	emitFailed(tr("Failed to download assets!"));
 }
 
 void OneSixUpdate::jarlibStart()
@@ -234,16 +232,23 @@ void OneSixUpdate::jarlibStart()
 	setStatus(tr("Getting the library files from Mojang..."));
 	QLOG_INFO() << m_inst->name() << ": downloading libraries";
 	OneSixInstance *inst = (OneSixInstance *)m_inst;
-	bool successful = inst->reloadVersion();
-	if (!successful)
+	try
+	{
+		inst->reloadVersion();
+	}
+	catch(MMCError & e)
+	{
+		emitFailed(e.cause());
+		return;
+	}
+	catch(...)
 	{
-		emitFailed("Failed to load the version description file. It might be "
-				   "corrupted, missing or simply too new.");
+		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<OneSixVersion> version = inst->getFullVersion();
+	std::shared_ptr<VersionFinal> version = inst->getFullVersion();
 	// minecraft.jar for this version
 	{
 		QString version_id = version->id;
@@ -326,6 +331,5 @@ void OneSixUpdate::jarlibFailed()
 {
 	QStringList failed = jarlibDownloadJob->getFailedFiles();
 	QString failed_all = failed.join("\n");
-	emitFailed("Failed to download the following files:\n" + failed_all +
-			   "\n\nPlease try again.");
+	emitFailed(tr("Failed to download the following files:\n%1\n\nPlease try again.").arg(failed_all));
 }
diff --git a/logic/OneSixVersion.cpp b/logic/OneSixVersion.cpp
deleted file mode 100644
index 06e748bd..00000000
--- a/logic/OneSixVersion.cpp
+++ /dev/null
@@ -1,221 +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 "OneSixVersion.h"
-
-#include <QDebug>
-#include <QFile>
-
-#include "OneSixVersionBuilder.h"
-
-OneSixVersion::OneSixVersion(OneSixInstance *instance, QObject *parent)
-	: QAbstractListModel(parent), m_instance(instance)
-{
-	clear();
-}
-
-bool OneSixVersion::reload(QWidget *widgetParent, const bool onlyVanilla, const QStringList &external)
-{
-	beginResetModel();
-	bool ret = OneSixVersionBuilder::build(this, m_instance, widgetParent, onlyVanilla, external);
-	endResetModel();
-	return ret;
-}
-
-void OneSixVersion::clear()
-{
-	beginResetModel();
-	id.clear();
-	time.clear();
-	releaseTime.clear();
-	type.clear();
-	assets.clear();
-	processArguments.clear();
-	minecraftArguments.clear();
-	minimumLauncherVersion = 0xDEADBEAF;
-	mainClass.clear();
-	libraries.clear();
-	tweakers.clear();
-	versionFiles.clear();
-	endResetModel();
-}
-
-void OneSixVersion::dump() const
-{
-	qDebug().nospace() << "OneSixVersion("
-				  << "\n\tid=" << id
-				  << "\n\ttime=" << time
-				  << "\n\treleaseTime=" << releaseTime
-				  << "\n\ttype=" << type
-				  << "\n\tassets=" << assets
-				  << "\n\tprocessArguments=" << processArguments
-				  << "\n\tminecraftArguments=" << minecraftArguments
-				  << "\n\tminimumLauncherVersion=" << minimumLauncherVersion
-				  << "\n\tmainClass=" << mainClass
-				  << "\n\tlibraries=";
-	for (auto lib : libraries)
-	{
-		qDebug().nospace() << "\n\t\t" << lib.get();
-	}
-	qDebug().nospace() << "\n)";
-}
-
-bool OneSixVersion::canRemove(const int index) const
-{
-	if (index < versionFiles.size())
-	{
-		return versionFiles.at(index).id != "org.multimc.version.json";
-	}
-	return false;
-}
-
-QString OneSixVersion::versionFileId(const int index) const
-{
-	if (index < 0 || index >= versionFiles.size())
-	{
-		return QString();
-	}
-	return versionFiles.at(index).id;
-}
-
-bool OneSixVersion::remove(const int index)
-{
-	if (canRemove(index))
-	{
-		return QFile::remove(versionFiles.at(index).filename);
-	}
-	return false;
-}
-
-QList<std::shared_ptr<OneSixLibrary> > OneSixVersion::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> > OneSixVersion::getActiveNativeLibs()
-{
-	QList<std::shared_ptr<OneSixLibrary> > output;
-	for (auto lib : libraries)
-	{
-		if (lib->isActive() && lib->isNative())
-		{
-			output.append(lib);
-		}
-	}
-	return output;
-}
-
-std::shared_ptr<OneSixVersion> OneSixVersion::fromJson(const QJsonObject &obj)
-{
-	std::shared_ptr<OneSixVersion> version(new OneSixVersion(0));
-	if (OneSixVersionBuilder::read(version.get(), obj))
-	{
-		return version;
-	}
-	return 0;
-}
-
-QVariant OneSixVersion::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 OneSixVersion::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 OneSixVersion::flags(const QModelIndex &index) const
-{
-	if (!index.isValid())
-		return Qt::NoItemFlags;
-	return Qt::ItemIsSelectable | Qt::ItemIsEnabled;
-}
-
-int OneSixVersion::rowCount(const QModelIndex &parent) const
-{
-	return versionFiles.size();
-}
-
-int OneSixVersion::columnCount(const QModelIndex &parent) const
-{
-	return 2;
-}
-
-QDebug operator<<(QDebug &dbg, const OneSixVersion *version)
-{
-	version->dump();
-	return dbg.maybeSpace();
-}
-QDebug operator<<(QDebug &dbg, const OneSixLibrary *library)
-{
-	dbg.nospace() << "OneSixLibrary("
-				  << "\n\t\t\trawName=" << library->rawName()
-				  << "\n\t\t\tname=" << library->name()
-				  << "\n\t\t\tversion=" << library->version()
-				  << "\n\t\t\ttype=" << library->type()
-				  << "\n\t\t\tisActive=" << library->isActive()
-				  << "\n\t\t\tisNative=" << library->isNative()
-				  << "\n\t\t\tdownloadUrl=" << library->downloadUrl()
-				  << "\n\t\t\tstoragePath=" << library->storagePath()
-				  << "\n\t\t\tabsolutePath=" << library->absoluteUrl()
-				  << "\n\t\t\thint=" << library->hint();
-	dbg.nospace() << "\n\t\t)";
-	return dbg.maybeSpace();
-}
diff --git a/logic/OneSixVersionBuilder.cpp b/logic/OneSixVersionBuilder.cpp
index f6917697..8eacbce4 100644
--- a/logic/OneSixVersionBuilder.cpp
+++ b/logic/OneSixVersionBuilder.cpp
@@ -26,806 +26,37 @@
 #include <QDir>
 #include <QDebug>
 
-#include "OneSixVersion.h"
+#include "VersionFinal.h"
 #include "OneSixInstance.h"
 #include "OneSixRule.h"
+#include "VersionFile.h"
+#include "MMCJson.h"
 #include "modutils.h"
 #include "logger/QsLog.h"
 
-#define CURRENT_MINIMUM_LAUNCHER_VERSION 14
-
-struct VersionFile
-{
-	int order;
-	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;
-
-	struct Library
-	{
-		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;
-	};
-	bool shouldOverwriteLibs = false;
-	QList<Library> overwriteLibs;
-	QList<Library> addLibs;
-	QList<QString> removeLibs;
-
-	enum ApplyError
-	{
-		LauncherVersionError,
-		OtherError,
-		NoApplyError
-	};
-
-	static Library fromLibraryJson(const QJsonObject &libObj, const QString &filename,
-								   bool &isError)
-	{
-		isError = true;
-		Library out;
-		if (!libObj.contains("name"))
-		{
-			QLOG_ERROR() << filename << "contains a library that doesn't have a 'name' field";
-			return out;
-		}
-		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"))
-		{
-			if (!libObj.value("extract").isObject())
-			{
-				QLOG_ERROR()
-					<< filename
-					<< "contains a library with an 'extract' field that's not an object";
-				return out;
-			}
-			QJsonObject extractObj = libObj.value("extract").toObject();
-			if (!extractObj.contains("exclude") || !extractObj.value("exclude").isArray())
-			{
-				QLOG_ERROR() << filename
-							 << "contains a library with an invalid 'extract' field";
-				return out;
-			}
-			out.applyExcludes = true;
-			QJsonArray excludeArray = extractObj.value("exclude").toArray();
-			for (auto excludeVal : excludeArray)
-			{
-				if (!excludeVal.isString())
-				{
-					QLOG_WARN() << filename << "contains a library that contains an 'extract' "
-											   "field that contains an invalid 'exclude' entry "
-											   "(skipping)";
-				}
-				else
-				{
-					out.excludes.append(excludeVal.toString());
-				}
-			}
-		}
-		if (libObj.contains("natives"))
-		{
-			if (!libObj.value("natives").isObject())
-			{
-				QLOG_ERROR()
-					<< filename
-					<< "contains a library with a 'natives' field that's not an object";
-				return out;
-			}
-			out.applyNatives = true;
-			QJsonObject nativesObj = libObj.value("natives").toObject();
-			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.natives.append(qMakePair(opSys, it.value().toString()));
-				}
-			}
-		}
-		if (libObj.contains("rules"))
-		{
-			out.applyRules = true;
-			out.rules = rulesFromJsonV4(libObj);
-		}
-		isError = false;
-		return out;
-	}
-	static VersionFile fromJson(const QJsonDocument &doc, const QString &filename,
-								const bool requireOrder, bool &isError, const OneSixVersionBuilder::ParseFlags flags = OneSixVersionBuilder::NoFlags)
-	{
-		VersionFile out;
-		isError = true;
-		if (doc.isEmpty() || doc.isNull())
-		{
-			QLOG_ERROR() << filename << "is empty or null";
-			return out;
-		}
-		if (!doc.isObject())
-		{
-			QLOG_ERROR() << "The root of" << filename << "is not an object";
-			return out;
-		}
-
-		QJsonObject root = doc.object();
-
-		if (requireOrder)
-		{
-			if (root.contains("order"))
-			{
-				if (root.value("order").isDouble())
-				{
-					out.order = root.value("order").toDouble();
-				}
-				else
-				{
-					QLOG_ERROR() << "'order' field contains an invalid value in" << filename;
-					return out;
-				}
-			}
-			else
-			{
-				QLOG_ERROR() << filename << "doesn't contain an order field";
-			}
-		}
-
-		out.name = root.value("name").toString();
-		out.fileId = root.value("fileId").toString();
-		out.version = root.value("version").toString();
-		out.mcVersion = root.value("mcVersion").toString();
-		out.filename = filename;
-
-		auto readString = [root, filename](const QString &key, QString &variable)
-		{
-			if (root.contains(key))
-			{
-				QJsonValue val = root.value(key);
-				if (!val.isString())
-				{
-					QLOG_WARN() << key << "is not a string in" << filename << "(skipping)";
-				}
-				else
-				{
-					variable = val.toString();
-				}
-			}
-		};
-
-		if (!(flags & OneSixVersionBuilder::IsFTBPackJson))
-		{
-			readString("id", out.id);
-		}
-		readString("mainClass", out.mainClass);
-		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);
-		readString("assets", out.assets);
-		if (root.contains("minimumLauncherVersion"))
-		{
-			QJsonValue val = root.value("minimumLauncherVersion");
-			if (!val.isDouble())
-			{
-				QLOG_WARN() << "minimumLauncherVersion is not an int in" << filename
-							<< "(skipping)";
-			}
-			else
-			{
-				out.minimumLauncherVersion = val.toDouble();
-			}
-		}
-
-		if (root.contains("tweakers"))
-		{
-			QJsonValue tweakersVal = root.value("tweakers");
-			if (!tweakersVal.isArray())
-			{
-				QLOG_ERROR() << filename
-							 << "contains a 'tweakers' field, but it's not an array";
-				return out;
-			}
-			out.shouldOverwriteTweakers = true;
-			QJsonArray tweakers = root.value("tweakers").toArray();
-			for (auto tweakerVal : tweakers)
-			{
-				if (!tweakerVal.isString())
-				{
-					QLOG_ERROR() << filename
-								 << "contains a 'tweakers' field entry that's not a string";
-					return out;
-				}
-				out.overwriteTweakers.append(tweakerVal.toString());
-			}
-		}
-		if (root.contains("+tweakers"))
-		{
-			QJsonValue tweakersVal = root.value("+tweakers");
-			if (!tweakersVal.isArray())
-			{
-				QLOG_ERROR() << filename
-							 << "contains a '+tweakers' field, but it's not an array";
-				return out;
-			}
-			QJsonArray tweakers = root.value("+tweakers").toArray();
-			for (auto tweakerVal : tweakers)
-			{
-				if (!tweakerVal.isString())
-				{
-					QLOG_ERROR() << filename
-								 << "contains a '+tweakers' field entry that's not a string";
-					return out;
-				}
-				out.addTweakers.append(tweakerVal.toString());
-			}
-		}
-		if (root.contains("-tweakers"))
-		{
-			QJsonValue tweakersVal = root.value("-tweakers");
-			if (!tweakersVal.isArray())
-			{
-				QLOG_ERROR() << filename
-							 << "contains a '-tweakers' field, but it's not an array";
-				return out;
-			}
-			out.shouldOverwriteTweakers = true;
-			QJsonArray tweakers = root.value("-tweakers").toArray();
-			for (auto tweakerVal : tweakers)
-			{
-				if (!tweakerVal.isString())
-				{
-					QLOG_ERROR() << filename
-								 << "contains a '-tweakers' field entry that's not a string";
-					return out;
-				}
-				out.removeTweakers.append(tweakerVal.toString());
-			}
-		}
-
-		if (root.contains("libraries"))
-		{
-			out.shouldOverwriteLibs = !(flags & OneSixVersionBuilder::IsFTBPackJson);
-			QJsonValue librariesVal = root.value("libraries");
-			if (!librariesVal.isArray())
-			{
-				QLOG_ERROR() << filename
-							 << "contains a 'libraries' field, but its not an array";
-				return out;
-			}
-			QJsonArray librariesArray = librariesVal.toArray();
-			for (auto libVal : librariesArray)
-			{
-				if (!libVal.isObject())
-				{
-					QLOG_ERROR() << filename << "contains a library that's not an object";
-					return out;
-				}
-				QJsonObject libObj = libVal.toObject();
-				bool error;
-				Library lib = fromLibraryJson(libObj, filename, error);
-				if (error)
-				{
-					QLOG_ERROR() << "Error while reading a library entry in" << filename;
-					return out;
-				}
-				if (flags & OneSixVersionBuilder::IsFTBPackJson)
-				{
-					lib.hint = "local";
-					lib.insertType = Library::Prepend;
-					out.addLibs.prepend(lib);
-				}
-				else
-				{
-					out.overwriteLibs.append(lib);
-				}
-			}
-		}
-		if (root.contains("+libraries"))
-		{
-			QJsonValue librariesVal = root.value("+libraries");
-			if (!librariesVal.isArray())
-			{
-				QLOG_ERROR() << filename
-							 << "contains a '+libraries' field, but its not an array";
-				return out;
-			}
-			QJsonArray librariesArray = librariesVal.toArray();
-			for (auto libVal : librariesArray)
-			{
-				if (!libVal.isObject())
-				{
-					QLOG_ERROR() << filename << "contains a library that's not an object";
-					return out;
-				}
-				QJsonObject libObj = libVal.toObject();
-				bool error;
-				Library lib = fromLibraryJson(libObj, filename, error);
-				if (error)
-				{
-					QLOG_ERROR() << "Error while reading a library entry in" << filename;
-					return out;
-				}
-				if (!libObj.contains("insert"))
-				{
-					QLOG_ERROR() << "Missing 'insert' field in '+libraries' field in"
-								 << filename;
-					return out;
-				}
-				QJsonValue insertVal = libObj.value("insert");
-				QString insertString;
-				{
-					if (insertVal.isString())
-					{
-						insertString = insertVal.toString();
-					}
-					else if (insertVal.isObject())
-					{
-						QJsonObject insertObj = insertVal.toObject();
-						if (insertObj.isEmpty())
-						{
-							QLOG_ERROR() << "One library has an empty insert object in"
-										 << filename;
-							return out;
-						}
-						insertString = insertObj.keys().first();
-						lib.insertData = insertObj.value(insertString).toString();
-					}
-				}
-				if (insertString == "apply")
-				{
-					lib.insertType = Library::Apply;
-				}
-				else if (insertString == "prepend")
-				{
-					lib.insertType = Library::Prepend;
-				}
-				else if (insertString == "append")
-				{
-					lib.insertType = Library::Prepend;
-				}
-				else if (insertString == "replace")
-				{
-					lib.insertType = Library::Replace;
-				}
-				else
-				{
-					QLOG_ERROR() << "A '+' library in" << filename
-								 << "contains an invalid insert type";
-					return out;
-				}
-				if (libObj.contains("MMC-depend") && libObj.value("MMC-depend").isString())
-				{
-					const QString dependString = libObj.value("MMC-depend").toString();
-					if (dependString == "hard")
-					{
-						lib.dependType = Library::Hard;
-					}
-					else if (dependString == "soft")
-					{
-						lib.dependType = Library::Soft;
-					}
-					else
-					{
-						QLOG_ERROR() << "A '+' library in" << filename
-									 << "contains an invalid depend type";
-						return out;
-					}
-				}
-				out.addLibs.append(lib);
-			}
-		}
-		if (root.contains("-libraries"))
-		{
-			QJsonValue librariesVal = root.value("-libraries");
-			if (!librariesVal.isArray())
-			{
-				QLOG_ERROR() << filename
-							 << "contains a '-libraries' field, but its not an array";
-				return out;
-			}
-			QJsonArray librariesArray = librariesVal.toArray();
-			for (auto libVal : librariesArray)
-			{
-				if (!libVal.isObject())
-				{
-					QLOG_ERROR() << filename << "contains a library that's not an object";
-					return out;
-				}
-				QJsonObject libObj = libVal.toObject();
-				if (!libObj.contains("name"))
-				{
-					QLOG_ERROR() << filename << "contains a library without a name";
-					return out;
-				}
-				if (!libObj.value("name").isString())
-				{
-					QLOG_ERROR() << filename
-								 << "contains a library without a valid 'name' field";
-					return out;
-				}
-				out.removeLibs.append(libObj.value("name").toString());
-			}
-		}
-
-		isError = false;
-		return out;
-	}
-
-	static std::shared_ptr<OneSixLibrary> createLibrary(const Library &lib)
-	{
-		std::shared_ptr<OneSixLibrary> out(new OneSixLibrary(lib.name));
-		if (!lib.url.isEmpty())
-		{
-			out->setBaseUrl(lib.url);
-		}
-		out->setHint(lib.hint);
-		if (!lib.absoluteUrl.isEmpty())
-		{
-			out->setAbsoluteUrl(lib.absoluteUrl);
-		}
-		out->setAbsoluteUrl(lib.absoluteUrl);
-		out->extract_excludes = lib.excludes;
-		for (auto native : lib.natives)
-		{
-			out->addNative(native.first, native.second);
-		}
-		out->setRules(lib.rules);
-		out->finalize();
-		return out;
-	}
-	int findLibrary(QList<std::shared_ptr<OneSixLibrary>> haystack, const QString &needle)
-	{
-		for (int i = 0; i < haystack.size(); ++i)
-		{
-			if (QRegExp(needle, Qt::CaseSensitive, QRegExp::WildcardUnix)
-					.indexIn(haystack.at(i)->rawName()) != -1)
-			{
-				return i;
-			}
-		}
-		return -1;
-	}
-	ApplyError applyTo(OneSixVersion *version)
-	{
-		if (minimumLauncherVersion != -1)
-		{
-			if (minimumLauncherVersion > CURRENT_MINIMUM_LAUNCHER_VERSION)
-			{
-				QLOG_ERROR() << filename << "is for a different launcher version ("
-							 << minimumLauncherVersion << "), current supported is"
-							 << CURRENT_MINIMUM_LAUNCHER_VERSION;
-				return LauncherVersionError;
-			}
-		}
-
-		if (!version->id.isNull() && !mcVersion.isNull())
-		{
-			if (QRegExp(mcVersion, Qt::CaseInsensitive, QRegExp::Wildcard)
-					.indexIn(version->id) == -1)
-			{
-				QLOG_ERROR() << filename << "is for a different version of Minecraft";
-				return OtherError;
-			}
-		}
-
-		if (!id.isNull())
-		{
-			version->id = id;
-		}
-		if (!mainClass.isNull())
-		{
-			version->mainClass = mainClass;
-		}
-		if (!processArguments.isNull())
-		{
-			version->processArguments = processArguments;
-		}
-		if (!type.isNull())
-		{
-			version->type = type;
-		}
-		if (!releaseTime.isNull())
-		{
-			version->releaseTime = releaseTime;
-		}
-		if (!time.isNull())
-		{
-			version->time = time;
-		}
-		if (!assets.isNull())
-		{
-			version->assets = assets;
-		}
-		if (minimumLauncherVersion >= 0)
-		{
-			version->minimumLauncherVersion = minimumLauncherVersion;
-		}
-		if (!overwriteMinecraftArguments.isNull())
-		{
-			version->minecraftArguments = overwriteMinecraftArguments;
-		}
-		if (!addMinecraftArguments.isNull())
-		{
-			version->minecraftArguments += addMinecraftArguments;
-		}
-		if (!removeMinecraftArguments.isNull())
-		{
-			version->minecraftArguments.remove(removeMinecraftArguments);
-		}
-		if (shouldOverwriteTweakers)
-		{
-			version->tweakers = overwriteTweakers;
-		}
-		for (auto tweaker : addTweakers)
-		{
-			version->tweakers += tweaker;
-		}
-		for (auto tweaker : removeTweakers)
-		{
-			version->tweakers.removeAll(tweaker);
-		}
-		if (shouldOverwriteLibs)
-		{
-			version->libraries.clear();
-			for (auto lib : overwriteLibs)
-			{
-				version->libraries.append(createLibrary(lib));
-			}
-		}
-		for (auto lib : addLibs)
-		{
-			switch (lib.insertType)
-			{
-			case Library::Apply:
-			{
-
-				int index = findLibrary(version->libraries, lib.name);
-				if (index >= 0)
-				{
-					auto library = version->libraries[index];
-					if (!lib.url.isNull())
-					{
-						library->setBaseUrl(lib.url);
-					}
-					if (!lib.hint.isNull())
-					{
-						library->setHint(lib.hint);
-					}
-					if (!lib.absoluteUrl.isNull())
-					{
-						library->setAbsoluteUrl(lib.absoluteUrl);
-					}
-					if (lib.applyExcludes)
-					{
-						library->extract_excludes = lib.excludes;
-					}
-					if (lib.applyNatives)
-					{
-						library->clearSuffixes();
-						for (auto native : lib.natives)
-						{
-							library->addNative(native.first, native.second);
-						}
-					}
-					if (lib.applyRules)
-					{
-						library->setRules(lib.rules);
-					}
-					library->finalize();
-				}
-				else
-				{
-					QLOG_WARN() << "Couldn't find" << lib.insertData << "(skipping)";
-				}
-				break;
-			}
-			case Library::Append:
-			case Library::Prepend:
-			{
-
-				const int startOfVersion = lib.name.lastIndexOf(':') + 1;
-				const int index =
-					findLibrary(version->libraries,
-								QString(lib.name).replace(startOfVersion, INT_MAX, '*'));
-				if (index < 0)
-				{
-					if (lib.insertType == Library::Append)
-					{
-						version->libraries.append(createLibrary(lib));
-					}
-					else
-					{
-						version->libraries.prepend(createLibrary(lib));
-					}
-				}
-				else
-				{
-					auto otherLib = version->libraries.at(index);
-					const Util::Version ourVersion = lib.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
-					if (otherLib->dependType == OneSixLibrary::Hard)
-					{
-						// we need a higher version, or we're hard to and the versions aren't
-						// equal
-						if (ourVersion > otherVersion ||
-							(lib.dependType == Library::Hard && ourVersion != otherVersion))
-						{
-							QLOG_ERROR() << "Error resolving library dependencies between"
-										 << otherLib->rawName() << "and" << lib.name << "in"
-										 << filename;
-							return OtherError;
-						}
-						else
-						{
-							// the library is already existing, so we don't have to do anything
-						}
-					}
-					else if (otherLib->dependType == OneSixLibrary::Soft)
-					{
-						// if we are higher it means we should update
-						if (ourVersion > otherVersion)
-						{
-							auto library = createLibrary(lib);
-							if (Util::Version(otherLib->minVersion) < ourVersion)
-							{
-								library->minVersion = ourVersion.toString();
-							}
-							version->libraries.replace(index, library);
-						}
-						else
-						{
-							// our version is smaller than the existing version, but we require
-							// it: fail
-							if (lib.dependType == Library::Hard)
-							{
-								QLOG_ERROR() << "Error resolving library dependencies between"
-											 << otherLib->rawName() << "and" << lib.name << "in"
-											 << filename;
-								return OtherError;
-							}
-						}
-					}
-				}
-				break;
-			}
-			case Library::Replace:
-			{
-				int index = findLibrary(version->libraries, lib.insertData);
-				if (index >= 0)
-				{
-					version->libraries.replace(index, createLibrary(lib));
-				}
-				else
-				{
-					QLOG_WARN() << "Couldn't find" << lib.insertData << "(skipping)";
-				}
-				break;
-			}
-			}
-		}
-		for (auto lib : removeLibs)
-		{
-			int index = findLibrary(version->libraries, lib);
-			if (index >= 0)
-			{
-				version->libraries.removeAt(index);
-			}
-			else
-			{
-				QLOG_WARN() << "Couldn't find" << lib << "(skipping)";
-			}
-		}
-
-		OneSixVersion::VersionFile versionFile;
-		versionFile.name = name;
-		versionFile.id = fileId;
-		versionFile.version = this->version;
-		versionFile.mcVersion = mcVersion;
-		versionFile.filename = filename;
-		versionFile.order = order;
-		version->versionFiles.append(versionFile);
-
-		return NoApplyError;
-	}
-};
-
 OneSixVersionBuilder::OneSixVersionBuilder()
 {
 }
 
-bool OneSixVersionBuilder::build(OneSixVersion *version, OneSixInstance *instance,
-								 QWidget *widgetParent, const bool onlyVanilla, const QStringList &external)
+void OneSixVersionBuilder::build(VersionFinal *version, OneSixInstance *instance,
+								 const bool onlyVanilla, const QStringList &external)
 {
 	OneSixVersionBuilder builder;
 	builder.m_version = version;
 	builder.m_instance = instance;
-	builder.m_widgetParent = widgetParent;
-	return builder.build(onlyVanilla, external);
+	builder.buildInternal(onlyVanilla, external);
 }
 
-bool OneSixVersionBuilder::read(OneSixVersion *version, const QJsonObject &obj)
+void OneSixVersionBuilder::readJsonAndApplyToVersion(VersionFinal *version,
+													 const QJsonObject &obj)
 {
 	OneSixVersionBuilder builder;
 	builder.m_version = version;
 	builder.m_instance = 0;
-	builder.m_widgetParent = 0;
-	return builder.read(obj);
+	builder.readJsonAndApply(obj);
 }
 
-bool OneSixVersionBuilder::build(const bool onlyVanilla, const QStringList &external)
+void OneSixVersionBuilder::buildInternal(const bool onlyVanilla, const QStringList &external)
 {
 	m_version->clear();
 
@@ -833,245 +64,194 @@ bool OneSixVersionBuilder::build(const bool onlyVanilla, const QStringList &exte
 	QDir patches(root.absoluteFilePath("patches/"));
 
 	// if we do external files, do just those.
-	if(!external.isEmpty()) for (auto fileName : external)
-	{
-		QLOG_INFO() << "Reading" << fileName;
-		VersionFile file;
-		ParseFlags flags = fileName.endsWith("pack.json") ? IsFTBPackJson : NoFlags;
-		if (!read(QFileInfo(fileName), false, &file, flags))
-		{
-			return false;
+	if (!external.isEmpty())
+		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->version = QString();
+			file->mcVersion = QString();
+			file->applyTo(m_version);
+			m_version->versionFiles.append(file);
 		}
-		file.name = QFileInfo(fileName).fileName();
-		file.fileId = "org.multimc.external." + file.name;
-		file.version = QString();
-		file.mcVersion = QString();
-		bool isError = false;
-		auto errorcode = file.applyTo(m_version);
-		if(errorcode != VersionFile::NoApplyError)
-			return false;
-	}
 	// else, if there's custom json, we just do that.
 	else if (QFile::exists(root.absoluteFilePath("custom.json")))
 	{
 		QLOG_INFO() << "Reading custom.json";
-		VersionFile file;
-		if (!read(QFileInfo(root.absoluteFilePath("custom.json")), false, &file))
-		{
-			return false;
-		}
-		file.name = "custom.json";
-		file.filename = "custom.json";
-		file.fileId = "org.multimc.custom.json";
-		file.version = QString();
-		auto errorcode = file.applyTo(m_version);
-		if(errorcode != VersionFile::NoApplyError)
-			return false;
-		// QObject::tr("The version descriptors of this instance are not compatible with the current version of MultiMC"));
+		auto file = parseJsonFile(QFileInfo(root.absoluteFilePath("custom.json")), false);
+		file->name = "custom.json";
+		file->filename = "custom.json";
+		file->fileId = "org.multimc.custom.json";
+		file->version = QString();
+		file->applyTo(m_version);
+		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";
-		VersionFile file;
-		if (!read(QFileInfo(root.absoluteFilePath("version.json")), false, &file))
-		{
-			return false;
-		}
-		file.name = "version.json";
-		file.fileId = "org.multimc.version.json";
-		file.version = m_instance->intendedVersionId();
-		file.mcVersion = m_instance->intendedVersionId();
-		auto error = file.applyTo(m_version);
-		if (error != VersionFile::NoApplyError)
-		{
-			QMessageBox::critical(
-						m_widgetParent, QObject::tr("Error"),
-						QObject::tr(
-							"Error while applying %1. Please check MultiMC-0.log for more info.")
-						.arg(root.absoluteFilePath("version.json")));
-			return false;
-		}
-
-		if (onlyVanilla)
-			break;
+	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->version = m_instance->intendedVersionId();
+			file->mcVersion = m_instance->intendedVersionId();
+			file->applyTo(m_version);
+			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<QString, int> overrideOrder = readOverrideOrders(m_instance);
+			// patches/
+			// load all, put into map for ordering, apply in the right order
 
-		QMap<int, QPair<QString, VersionFile>> files;
-		for (auto info : patches.entryInfoList(QStringList() << "*.json", QDir::Files))
-		{
-			QLOG_INFO() << "Reading" << info.fileName();
-			VersionFile file;
-			if (!read(info, true, &file))
-			{
-				return false;
-			}
-			if (overrideOrder.contains(file.fileId))
+			QMap<int, QPair<QString, VersionFilePtr>> files;
+			for (auto info : patches.entryInfoList(QStringList() << "*.json", QDir::Files))
 			{
-				file.order = overrideOrder.value(file.fileId);
-			}
-			if (files.contains(file.order))
-			{
-				QLOG_ERROR() << file.fileId << "has the same order as" << files[file.order].second.fileId;
-				return false;
+				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));
 			}
-			files.insert(file.order, qMakePair(info.fileName(), file));
-		}
-		for (auto order : files.keys())
-		{
-			QLOG_DEBUG() << "Applying file with order" << order;
-			auto filePair = files[order];
-			auto error = filePair.second.applyTo(m_version);
-			if (error != VersionFile::NoApplyError)
+			for (auto order : files.keys())
 			{
-				QMessageBox::critical(
-							m_widgetParent, QObject::tr("Error"),
-							QObject::tr("Error while applying %1. Please check MultiMC-0.log "
-										"for more info.").arg(filePair.first));
-				return false;
+				QLOG_DEBUG() << "Applying file with order" << order;
+				auto &filePair = files[order];
+				filePair.second->applyTo(m_version);
+				m_version->versionFiles.append(filePair.second);
 			}
-		}
-	} while(0);
+		} while (0);
 
 	// some final touches
+	finalizeVersion();
+}
+
+void OneSixVersionBuilder::finalizeVersion()
+{
+	if (m_version->assets.isEmpty())
 	{
-		if (m_version->assets.isEmpty())
+		m_version->assets = "legacy";
+	}
+	if (m_version->minecraftArguments.isEmpty())
+	{
+		QString toCompare = m_version->processArguments.toLower();
+		if (toCompare == "legacy")
 		{
-			m_version->assets = "legacy";
+			m_version->minecraftArguments = " ${auth_player_name} ${auth_session}";
 		}
-		if (m_version->minecraftArguments.isEmpty())
+		else if (toCompare == "username_session")
 		{
-			QString toCompare = m_version->processArguments.toLower();
-			if (toCompare == "legacy")
-			{
-				m_version->minecraftArguments = " ${auth_player_name} ${auth_session}";
-			}
-			else if (toCompare == "username_session")
-			{
-				m_version->minecraftArguments =
-					"--username ${auth_player_name} --session ${auth_session}";
-			}
-			else if (toCompare == "username_session_version")
-			{
-				m_version->minecraftArguments = "--username ${auth_player_name} "
-												"--session ${auth_session} "
-												"--version ${profile_name}";
-			}
+			m_version->minecraftArguments =
+				"--username ${auth_player_name} --session ${auth_session}";
+		}
+		else if (toCompare == "username_session_version")
+		{
+			m_version->minecraftArguments = "--username ${auth_player_name} "
+											"--session ${auth_session} "
+											"--version ${profile_name}";
 		}
 	}
-
-	return true;
 }
 
-bool OneSixVersionBuilder::read(const QJsonObject &obj)
+void OneSixVersionBuilder::readJsonAndApply(const QJsonObject &obj)
 {
 	m_version->clear();
 
-	bool isError = false;
-	VersionFile file = VersionFile::fromJson(QJsonDocument(obj), QString(), false, isError);
-	if (isError)
-	{
-		QMessageBox::critical(
-			m_widgetParent, QObject::tr("Error"),
-			QObject::tr("Error while reading. Please check MultiMC-0.log for more info."));
-		return false;
-	}
-	VersionFile::ApplyError error = file.applyTo(m_version);
-	if (error == VersionFile::OtherError)
-	{
-		QMessageBox::critical(
-			m_widgetParent, QObject::tr("Error"),
-			QObject::tr("Error while applying. Please check MultiMC-0.log for more info."));
-		return false;
-	}
-	else if (error == VersionFile::LauncherVersionError)
-	{
-		QMessageBox::critical(
-					m_widgetParent, QObject::tr("Error"),
-					QObject::tr("The version descriptors of this instance are not compatible with the current version of MultiMC"));
-		return false;
-	}
+	auto file = VersionFile::fromJson(QJsonDocument(obj), QString(), false);
+	// QObject::tr("Error while reading. Please check MultiMC-0.log for more info."));
 
-	return true;
+	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"));
 }
 
-bool OneSixVersionBuilder::read(const QFileInfo &fileInfo, const bool requireOrder,
-								VersionFile *out, const ParseFlags flags)
+VersionFilePtr OneSixVersionBuilder::parseJsonFile(const QFileInfo &fileInfo,
+												   const bool requireOrder, bool isFTB)
 {
 	QFile file(fileInfo.absoluteFilePath());
 	if (!file.open(QFile::ReadOnly))
 	{
-		QMessageBox::critical(
-			m_widgetParent, QObject::tr("Error"),
-			QObject::tr("Unable to open %1: %2").arg(file.fileName(), file.errorString()));
-		return false;
+		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)
 	{
-		QMessageBox::critical(m_widgetParent, QObject::tr("Error"),
-							  QObject::tr("Unable to parse %1: %2 at %3")
-								  .arg(file.fileName(), error.errorString())
-								  .arg(error.offset));
-		return false;
+		throw JSONValidationError(QObject::tr("Unable to process the version file %1: %2 at %3.")
+									  .arg(fileInfo.fileName(), error.errorString())
+									  .arg(error.offset));
 	}
-	bool isError = false;
-	*out = VersionFile::fromJson(doc, file.fileName(), requireOrder, isError, flags);
-	if (isError)
-	{
-		QMessageBox::critical(
-			m_widgetParent, QObject::tr("Error"),
-			QObject::tr("Error while reading %1. Please check MultiMC-0.log for more info.")
-				.arg(file.fileName()));
-		;
-	}
-	return true;
+	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;
-	if (QDir(instance->instanceRoot()).exists("order.json"))
+
+	// 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))
 	{
-		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";
-		}
-		else
+		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)
 		{
-			QJsonParseError error;
-			QJsonDocument doc = QJsonDocument::fromJson(orderFile.readAll(), &error);
-			if (error.error != QJsonParseError::NoError || !doc.isObject())
-			{
-				QLOG_ERROR() << "Couldn't parse" << orderFile.fileName() << ":"
-							 << error.errorString();
-				QLOG_WARN() << "Ignoring overriden order";
-			}
-			else
+			if (it.key().startsWith("org.multimc."))
 			{
-				QJsonObject obj = doc.object();
-				for (auto it = obj.begin(); it != obj.end(); ++it)
-				{
-					if (it.key().startsWith("org.multimc."))
-					{
-						continue;
-					}
-					out.insert(it.key(), it.value().toDouble());
-				}
+				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)
 {
@@ -1094,4 +274,3 @@ bool OneSixVersionBuilder::writeOverrideOrders(const QMap<QString, int> &order,
 	orderFile.write(QJsonDocument(obj).toJson(QJsonDocument::Indented));
 	return true;
 }
-
diff --git a/logic/OneSixVersionBuilder.h b/logic/OneSixVersionBuilder.h
index 8cf6f32f..8be3d9d3 100644
--- a/logic/OneSixVersionBuilder.h
+++ b/logic/OneSixVersionBuilder.h
@@ -17,39 +17,32 @@
 
 #include <QString>
 #include <QMap>
+#include "VersionFile.h"
 
-class OneSixVersion;
+class VersionFinal;
 class OneSixInstance;
-class QWidget;
 class QJsonObject;
 class QFileInfo;
-class VersionFile;
 
 class OneSixVersionBuilder
 {
 	OneSixVersionBuilder();
 public:
-	static bool build(OneSixVersion *version, OneSixInstance *instance, QWidget *widgetParent, const bool onlyVanilla, const QStringList &external);
-	static bool read(OneSixVersion *version, const QJsonObject &obj);
+	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);
 
-	enum ParseFlag
-	{
-		NoFlags = 0x0,
-		IsFTBPackJson = 0x1
-	};
-	Q_DECLARE_FLAGS(ParseFlags, ParseFlag)
-
 private:
-	OneSixVersion *m_version;
+	VersionFinal *m_version;
 	OneSixInstance *m_instance;
-	QWidget *m_widgetParent;
 
-	bool build(const bool onlyVanilla, const QStringList &external);
-	bool read(const QJsonObject &obj);
+	void buildInternal(const bool onlyVanilla, const QStringList &external);
+	void readJsonAndApply(const QJsonObject &obj);
+	void finalizeVersion();
 
-	bool read(const QFileInfo &fileInfo, const bool requireOrder, VersionFile *out, const ParseFlags flags = NoFlags);
+	VersionFilePtr parseJsonFile(const QFileInfo &fileInfo, const bool requireOrder,
+							  bool isFTB = false);
 };
-
-Q_DECLARE_OPERATORS_FOR_FLAGS(OneSixVersionBuilder::ParseFlags)
diff --git a/logic/VersionFile.cpp b/logic/VersionFile.cpp
new file mode 100644
index 00000000..831b086e
--- /dev/null
+++ b/logic/VersionFile.cpp
@@ -0,0 +1,535 @@
+#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"
+
+using namespace MMCJson;
+
+#define CURRENT_MINIMUM_LAUNCHER_VERSION 14
+
+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->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"))
+	{
+		out->applyNatives = true;
+		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->natives.append(qMakePair(opSys, it.value().toString()));
+			}
+		}
+	}
+	if (libObj.contains("rules"))
+	{
+		out->applyRules = true;
+		out->rules = rulesFromJsonV4(libObj);
+	}
+	return out;
+}
+
+VersionFilePtr VersionFile::fromJson(const QJsonDocument &doc, const QString &filename,
+								  const bool requireOrder, const bool isFTB)
+{
+	VersionFilePtr out(new VersionFile());
+	if (doc.isEmpty() || doc.isNull())
+	{
+		throw JSONValidationError(filename + " is empty or null");
+	}
+	if (!doc.isObject())
+	{
+		throw JSONValidationError("The root of " + filename + " is not an object");
+	}
+
+	QJsonObject root = doc.object();
+
+	if (requireOrder)
+	{
+		if (root.contains("order"))
+		{
+			out->order = ensureInteger(root.value("order"));
+		}
+		else
+		{
+			// FIXME: evaluate if we don't want to throw exceptions here instead
+			QLOG_ERROR() << filename << "doesn't contain an order field";
+		}
+	}
+
+	out->name = root.value("name").toString();
+	out->fileId = root.value("fileId").toString();
+	out->version = root.value("version").toString();
+	out->mcVersion = root.value("mcVersion").toString();
+	out->filename = filename;
+
+	auto readString = [root, filename](const QString & key, QString & variable)
+	{
+		if (root.contains(key))
+		{
+			variable = ensureString(root.value(key));
+		}
+	};
+
+	// FIXME: This should be ignored when applying.
+	if (!isFTB)
+	{
+		readString("id", out->id);
+	}
+
+	readString("mainClass", out->mainClass);
+	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);
+	readString("assets", out->assets);
+
+	if (root.contains("minimumLauncherVersion"))
+	{
+		out->minimumLauncherVersion = ensureInteger(root.value("minimumLauncherVersion"));
+	}
+
+	if (root.contains("tweakers"))
+	{
+		out->shouldOverwriteTweakers = true;
+		for (auto tweakerVal : ensureArray(root.value("tweakers")))
+		{
+			out->overwriteTweakers.append(ensureString(tweakerVal));
+		}
+	}
+
+	if (root.contains("+tweakers"))
+	{
+		for (auto tweakerVal : ensureArray(root.value("+tweakers")))
+		{
+			out->addTweakers.append(ensureString(tweakerVal));
+		}
+	}
+
+	if (root.contains("-tweakers"))
+	{
+		for (auto tweakerVal : ensureArray(root.value("-tweakers")))
+		{
+			out->removeTweakers.append(ensureString(tweakerVal));
+		}
+	}
+
+	if (root.contains("libraries"))
+	{
+		// FIXME: This should be done when applying.
+		out->shouldOverwriteLibs = !isFTB;
+		for (auto libVal : ensureArray(root.value("libraries")))
+		{
+			auto libObj = ensureObject(libVal);
+
+			auto lib = RawLibrary::fromJson(libObj, filename);
+			// FIXME: This should be done when applying.
+			if (isFTB)
+			{
+				lib->hint = "local";
+				lib->insertType = RawLibrary::Prepend;
+				out->addLibs.prepend(lib);
+			}
+			else
+			{
+				out->overwriteLibs.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");
+				}
+			}
+			out->addLibs.append(lib);
+		}
+	}
+	if (root.contains("-libraries"))
+	{
+		for (auto libVal : ensureArray(root.value("-libraries")))
+		{
+			auto libObj = ensureObject(libVal);
+			out->removeLibs.append(ensureString(libObj.value("name")));
+		}
+	}
+	return out;
+}
+
+OneSixLibraryPtr VersionFile::createLibrary(RawLibraryPtr lib)
+{
+	std::shared_ptr<OneSixLibrary> out(new OneSixLibrary(lib->name));
+	if (!lib->url.isEmpty())
+	{
+		out->setBaseUrl(lib->url);
+	}
+	out->setHint(lib->hint);
+	if (!lib->absoluteUrl.isEmpty())
+	{
+		out->setAbsoluteUrl(lib->absoluteUrl);
+	}
+	out->setAbsoluteUrl(lib->absoluteUrl);
+	out->extract_excludes = lib->excludes;
+	for (auto native : lib->natives)
+	{
+		out->addNative(native.first, native.second);
+	}
+	out->setRules(lib->rules);
+	out->finalize();
+	return out;
+}
+
+int VersionFile::findLibrary(QList<OneSixLibraryPtr> haystack, const QString &needle)
+{
+	for (int i = 0; i < haystack.size(); ++i)
+	{
+		if (QRegExp(needle, Qt::CaseSensitive, QRegExp::WildcardUnix)
+				.indexIn(haystack.at(i)->rawName()) != -1)
+		{
+			return i;
+		}
+	}
+	return -1;
+}
+
+void VersionFile::applyTo(VersionFinal *version)
+{
+	if (minimumLauncherVersion != -1)
+	{
+		if (minimumLauncherVersion > CURRENT_MINIMUM_LAUNCHER_VERSION)
+		{
+			throw LauncherVersionError(minimumLauncherVersion, CURRENT_MINIMUM_LAUNCHER_VERSION);
+		}
+	}
+
+	if (!version->id.isNull() && !mcVersion.isNull())
+	{
+		if (QRegExp(mcVersion, Qt::CaseInsensitive, QRegExp::Wildcard).indexIn(version->id) ==
+			-1)
+		{
+			throw MinecraftVersionMismatch(fileId, mcVersion, version->id);
+		}
+	}
+
+	if (!id.isNull())
+	{
+		version->id = id;
+	}
+	if (!mainClass.isNull())
+	{
+		version->mainClass = mainClass;
+	}
+	if (!processArguments.isNull())
+	{
+		version->processArguments = processArguments;
+	}
+	if (!type.isNull())
+	{
+		version->type = type;
+	}
+	if (!releaseTime.isNull())
+	{
+		version->releaseTime = releaseTime;
+	}
+	if (!time.isNull())
+	{
+		version->time = time;
+	}
+	if (!assets.isNull())
+	{
+		version->assets = assets;
+	}
+	if (minimumLauncherVersion >= 0)
+	{
+		version->minimumLauncherVersion = minimumLauncherVersion;
+	}
+	if (!overwriteMinecraftArguments.isNull())
+	{
+		version->minecraftArguments = overwriteMinecraftArguments;
+	}
+	if (!addMinecraftArguments.isNull())
+	{
+		version->minecraftArguments += addMinecraftArguments;
+	}
+	if (!removeMinecraftArguments.isNull())
+	{
+		version->minecraftArguments.remove(removeMinecraftArguments);
+	}
+	if (shouldOverwriteTweakers)
+	{
+		version->tweakers = overwriteTweakers;
+	}
+	for (auto tweaker : addTweakers)
+	{
+		version->tweakers += tweaker;
+	}
+	for (auto tweaker : removeTweakers)
+	{
+		version->tweakers.removeAll(tweaker);
+	}
+	if (shouldOverwriteLibs)
+	{
+		version->libraries.clear();
+		for (auto lib : overwriteLibs)
+		{
+			version->libraries.append(createLibrary(lib));
+		}
+	}
+	for (auto lib : addLibs)
+	{
+		switch (lib->insertType)
+		{
+		case RawLibrary::Apply:
+		{
+
+			int index = findLibrary(version->libraries, lib->name);
+			if (index >= 0)
+			{
+				auto library = version->libraries[index];
+				if (!lib->url.isNull())
+				{
+					library->setBaseUrl(lib->url);
+				}
+				if (!lib->hint.isNull())
+				{
+					library->setHint(lib->hint);
+				}
+				if (!lib->absoluteUrl.isNull())
+				{
+					library->setAbsoluteUrl(lib->absoluteUrl);
+				}
+				if (lib->applyExcludes)
+				{
+					library->extract_excludes = lib->excludes;
+				}
+				if (lib->applyNatives)
+				{
+					library->clearSuffixes();
+					for (auto native : lib->natives)
+					{
+						library->addNative(native.first, native.second);
+					}
+				}
+				if (lib->applyRules)
+				{
+					library->setRules(lib->rules);
+				}
+				library->finalize();
+			}
+			else
+			{
+				QLOG_WARN() << "Couldn't find" << lib->name << "(skipping)";
+			}
+			break;
+		}
+		case RawLibrary::Append:
+		case RawLibrary::Prepend:
+		{
+
+			const int startOfVersion = lib->name.lastIndexOf(':') + 1;
+			const int index = findLibrary(
+				version->libraries, QString(lib->name).replace(startOfVersion, INT_MAX, '*'));
+			if (index < 0)
+			{
+				if (lib->insertType == RawLibrary::Append)
+				{
+					version->libraries.append(createLibrary(lib));
+				}
+				else
+				{
+					version->libraries.prepend(createLibrary(lib));
+				}
+			}
+			else
+			{
+				auto otherLib = version->libraries.at(index);
+				const Util::Version ourVersion = lib->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
+				if (otherLib->dependType == OneSixLibrary::Hard)
+				{
+					// we need a higher version, or we're hard to and the versions aren't
+					// equal
+					if (ourVersion > otherVersion ||
+						(lib->dependType == RawLibrary::Hard && ourVersion != otherVersion))
+					{
+						throw VersionBuildError(
+							QObject::tr(
+								"Error resolving library dependencies between %1 and %2 in %3.")
+								.arg(otherLib->rawName(), lib->name, filename));
+					}
+					else
+					{
+						// the library is already existing, so we don't have to do anything
+					}
+				}
+				else if (otherLib->dependType == OneSixLibrary::Soft)
+				{
+					// if we are higher it means we should update
+					if (ourVersion > otherVersion)
+					{
+						auto library = createLibrary(lib);
+						if (Util::Version(otherLib->minVersion) < ourVersion)
+						{
+							library->minVersion = ourVersion.toString();
+						}
+						version->libraries.replace(index, library);
+					}
+					else
+					{
+						// our version is smaller than the existing version, but we require
+						// it: fail
+						if (lib->dependType == RawLibrary::Hard)
+						{
+							throw VersionBuildError(QObject::tr(
+								"Error resolving library dependencies between %1 and %2 in %3.")
+														.arg(otherLib->rawName(), lib->name,
+															 filename));
+						}
+					}
+				}
+			}
+			break;
+		}
+		case RawLibrary::Replace:
+		{
+			int index = findLibrary(version->libraries, lib->insertData);
+			if (index >= 0)
+			{
+				version->libraries.replace(index, createLibrary(lib));
+			}
+			else
+			{
+				QLOG_WARN() << "Couldn't find" << lib->insertData << "(skipping)";
+			}
+			break;
+		}
+		}
+	}
+	for (auto lib : removeLibs)
+	{
+		int index = findLibrary(version->libraries, lib);
+		if (index >= 0)
+		{
+			version->libraries.removeAt(index);
+		}
+		else
+		{
+			QLOG_WARN() << "Couldn't find" << lib << "(skipping)";
+		}
+	}
+}
diff --git a/logic/VersionFile.h b/logic/VersionFile.h
new file mode 100644
index 00000000..169a2066
--- /dev/null
+++ b/logic/VersionFile.h
@@ -0,0 +1,127 @@
+#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/VersionFinal.cpp b/logic/VersionFinal.cpp
new file mode 100644
index 00000000..a057ecdd
--- /dev/null
+++ b/logic/VersionFinal.cpp
@@ -0,0 +1,183 @@
+/* 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 "OneSixVersionBuilder.h"
+
+VersionFinal::VersionFinal(OneSixInstance *instance, QObject *parent)
+	: QAbstractListModel(parent), m_instance(instance)
+{
+	clear();
+}
+
+bool VersionFinal::reload(const bool onlyVanilla, const QStringList &external)
+{
+	//FIXME: source of epic failure.
+	beginResetModel();
+	OneSixVersionBuilder::build(this, m_instance, onlyVanilla, external);
+	endResetModel();
+}
+
+void VersionFinal::clear()
+{
+	beginResetModel();
+	id.clear();
+	time.clear();
+	releaseTime.clear();
+	type.clear();
+	assets.clear();
+	processArguments.clear();
+	minecraftArguments.clear();
+	minimumLauncherVersion = 0xDEADBEAF;
+	mainClass.clear();
+	libraries.clear();
+	tweakers.clear();
+	versionFiles.clear();
+	endResetModel();
+}
+
+bool VersionFinal::canRemove(const int index) const
+{
+	if (index < versionFiles.size())
+	{
+		return versionFiles.at(index)->fileId != "org.multimc.version.json";
+	}
+	return false;
+}
+
+QString VersionFinal::versionFileId(const int index) const
+{
+	if (index < 0 || index >= versionFiles.size())
+	{
+		return QString();
+	}
+	return versionFiles.at(index)->fileId;
+}
+
+bool VersionFinal::remove(const int index)
+{
+	if (canRemove(index))
+	{
+		return QFile::remove(versionFiles.at(index)->filename);
+	}
+	return false;
+}
+
+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;
+}
diff --git a/logic/OneSixVersion.h b/logic/VersionFinal.h
index fee47fa3..99fd5ff0 100644
--- a/logic/OneSixVersion.h
+++ b/logic/VersionFinal.h
@@ -22,14 +22,15 @@
 #include <memory>
 
 #include "OneSixLibrary.h"
+#include "VersionFile.h"
 
 class OneSixInstance;
 
-class OneSixVersion : public QAbstractListModel
+class VersionFinal : public QAbstractListModel
 {
 	Q_OBJECT
 public:
-	explicit OneSixVersion(OneSixInstance *instance, QObject *parent = 0);
+	explicit VersionFinal(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;
@@ -37,7 +38,7 @@ public:
 	virtual int columnCount(const QModelIndex &parent) const;
 	virtual Qt::ItemFlags flags(const QModelIndex &index) const;
 
-	bool reload(QWidget *widgetParent, const bool onlyVanilla = false, const QStringList &external = QStringList());
+	bool reload(const bool onlyVanilla = false, const QStringList &external = QStringList());
 	void clear();
 
 	void dump() const;
@@ -54,7 +55,7 @@ public:
 	QList<std::shared_ptr<OneSixLibrary>> getActiveNormalLibs();
 	QList<std::shared_ptr<OneSixLibrary>> getActiveNativeLibs();
 
-	static std::shared_ptr<OneSixVersion> fromJson(const QJsonObject &obj);
+	static std::shared_ptr<VersionFinal> fromJson(const QJsonObject &obj);
 
 	// data members
 public:
@@ -118,20 +119,8 @@ public:
 	*/
 	// QList<Rule> rules;
 
-	struct VersionFile
-	{
-		QString name;
-		QString id;
-		QString version;
-		QString mcVersion;
-		QString filename;
-		int order;
-	};
-	QList<VersionFile> versionFiles;
+	QList<VersionFilePtr> versionFiles;
 
 private:
 	OneSixInstance *m_instance;
 };
-
-QDebug operator<<(QDebug &dbg, const OneSixVersion *version);
-QDebug operator<<(QDebug &dbg, const OneSixLibrary *library);
diff --git a/logic/lists/LiteLoaderVersionList.cpp b/logic/lists/LiteLoaderVersionList.cpp
index b8cea442..ef95eefd 100644
--- a/logic/lists/LiteLoaderVersionList.cpp
+++ b/logic/lists/LiteLoaderVersionList.cpp
@@ -92,7 +92,6 @@ void LiteLoaderVersionList::updateListData(QList<BaseVersionPtr> versions)
 LLListLoadTask::LLListLoadTask(LiteLoaderVersionList *vlist)
 {
 	m_list = vlist;
-	vlistReply = nullptr;
 }
 
 LLListLoadTask::~LLListLoadTask()
@@ -102,23 +101,49 @@ LLListLoadTask::~LLListLoadTask()
 void LLListLoadTask::executeTask()
 {
 	setStatus(tr("Loading LiteLoader version list..."));
-	auto worker = MMC->qnam();
-	vlistReply = worker->get(QNetworkRequest(QUrl(URLConstants::LITELOADER_URL)));
-	connect(vlistReply, SIGNAL(finished()), this, SLOT(listDownloaded()));
+	auto job = new NetJob("Version index");
+	// we do not care if the version is stale or not.
+	auto liteloaderEntry = MMC->metacache()->resolveEntry("liteloader", "versions.json");
+
+	// verify by poking the server.
+	liteloaderEntry->stale = true;
+
+	job->addNetAction(listDownload = CacheDownload::make(QUrl(URLConstants::LITELOADER_URL),
+														 liteloaderEntry));
+
+	connect(listDownload.get(), SIGNAL(failed(int)), SLOT(listFailed()));
+
+	listJob.reset(job);
+	connect(listJob.get(), SIGNAL(succeeded()), SLOT(listDownloaded()));
+	connect(listJob.get(), SIGNAL(progress(qint64, qint64)), SIGNAL(progress(qint64, qint64)));
+	listJob->start();
+}
+
+void LLListLoadTask::listFailed()
+{
+	emitFailed("Failed to load LiteLoader version list.");
+	return;
 }
 
 void LLListLoadTask::listDownloaded()
 {
-	if (vlistReply->error() != QNetworkReply::NoError)
+	QByteArray data;
 	{
-		vlistReply->deleteLater();
-		emitFailed("Failed to load LiteLoader version list" + vlistReply->errorString());
-		return;
+		auto dlJob = listDownload;
+		auto filename = std::dynamic_pointer_cast<CacheDownload>(dlJob)->getTargetFilepath();
+		QFile listFile(filename);
+		if (!listFile.open(QIODevice::ReadOnly))
+		{
+			emitFailed("Failed to open the LiteLoader version list.");
+			return;
+		}
+		data = listFile.readAll();
+		listFile.close();
+		dlJob.reset();
 	}
 
 	QJsonParseError jsonError;
-	QJsonDocument jsonDoc = QJsonDocument::fromJson(vlistReply->readAll(), &jsonError);
-	vlistReply->deleteLater();
+	QJsonDocument jsonDoc = QJsonDocument::fromJson(data, &jsonError);
 
 	if (jsonError.error != QJsonParseError::NoError)
 	{
@@ -140,7 +165,12 @@ void LLListLoadTask::listDownloaded()
 		emitFailed("Error parsing version list JSON: missing 'versions' object");
 		return;
 	}
-	const QJsonObject versions = root.value("versions").toObject();
+
+	auto meta = root.value("meta").toObject();
+	QString description = meta.value("description").toString(tr("This is a lightweight loader for mods that don't change game mechanics."));
+	QString defaultUrl = meta.value("url").toString("http://dl.liteloader.com");
+	QString authors = meta.value("authors").toString("Mumfrey");
+	auto versions = root.value("versions").toObject();
 
 	QList<BaseVersionPtr> tempList;
 	for (auto vIt = versions.begin(); vIt != versions.end(); ++vIt)
@@ -170,6 +200,9 @@ void LLListLoadTask::listDownloaded()
 			version->md5 = artefact.value("md5").toString();
 			version->timestamp = artefact.value("timestamp").toDouble();
 			version->tweakClass = artefact.value("tweakClass").toString();
+			version->authors = authors;
+			version->description = description;
+			version->defaultUrl = defaultUrl;
 			const QJsonArray libs = artefact.value("libraries").toArray();
 			for (auto lIt = libs.begin(); lIt != libs.end(); ++lIt)
 			{
diff --git a/logic/lists/LiteLoaderVersionList.h b/logic/lists/LiteLoaderVersionList.h
index 8f761caf..bfc913e5 100644
--- a/logic/lists/LiteLoaderVersionList.h
+++ b/logic/lists/LiteLoaderVersionList.h
@@ -22,6 +22,7 @@
 #include "BaseVersionList.h"
 #include "logic/tasks/Task.h"
 #include "logic/BaseVersion.h"
+#include <logic/net/NetJob.h>
 
 class LLListLoadTask;
 class QNetworkReply;
@@ -46,6 +47,7 @@ public:
 		return version;
 	}
 
+	// important info
 	QString version;
 	QString file;
 	QString mcVersion;
@@ -54,6 +56,11 @@ public:
 	bool isLatest;
 	QString tweakClass;
 	QStringList libraries;
+
+	// meta
+	QString defaultUrl;
+	QString description;
+	QString authors;
 };
 typedef std::shared_ptr<LiteLoaderVersion> LiteLoaderVersionPtr;
 
@@ -96,8 +103,10 @@ public:
 protected
 slots:
 	void listDownloaded();
+	void listFailed();
 
 protected:
-	QNetworkReply *vlistReply;
+	NetJobPtr listJob;
+	CacheDownloadPtr listDownload;
 	LiteLoaderVersionList *m_list;
 };
diff --git a/logic/net/PasteUpload.cpp b/logic/net/PasteUpload.cpp
index fa54d084..402eb400 100644
--- a/logic/net/PasteUpload.cpp
+++ b/logic/net/PasteUpload.cpp
@@ -25,7 +25,7 @@ void PasteUpload::executeTask()
 
 	m_reply = std::shared_ptr<QNetworkReply>(rep);
 	connect(rep, &QNetworkReply::downloadProgress, [&](qint64 value, qint64 max)
-	{ setProgress(value / max * 100); });
+	{ setProgress(value / qMax((qint64)1, max) * 100); });
 	connect(rep, SIGNAL(error(QNetworkReply::NetworkError)), this,
 			SLOT(downloadError(QNetworkReply::NetworkError)));
 	connect(rep, SIGNAL(finished()), this, SLOT(downloadFinished()));
@@ -52,10 +52,9 @@ void PasteUpload::downloadFinished()
 			emitFailed(jsonError.errorString());
 			return;
 		}
-		QString error;
-		if (!parseResult(doc, &error))
+		if (!parseResult(doc))
 		{
-			emitFailed(error);
+			emitFailed(tr("paste.ee returned an error. Please consult the logs for more information"));
 			return;
 		}
 	}
@@ -69,13 +68,13 @@ void PasteUpload::downloadFinished()
 	emitSucceeded();
 }
 
-bool PasteUpload::parseResult(QJsonDocument doc, QString *parseError)
+bool PasteUpload::parseResult(QJsonDocument doc)
 {
 	auto object = doc.object();
 	auto status = object.value("status").toString("error");
 	if (status == "error")
 	{
-		parseError = new QString(object.value("error").toString());
+		QLOG_ERROR() << "paste.ee reported error:" << QString(object.value("error").toString());
 		return false;
 	}
 	// FIXME: not the place for GUI things.
diff --git a/logic/net/PasteUpload.h b/logic/net/PasteUpload.h
index 917a0016..83876c17 100644
--- a/logic/net/PasteUpload.h
+++ b/logic/net/PasteUpload.h
@@ -14,7 +14,7 @@ protected:
 	virtual void executeTask();
 
 private:
-	bool parseResult(QJsonDocument doc, QString *parseError);
+	bool parseResult(QJsonDocument doc);
 	QString m_text;
 	QString m_error;
 	QWidget *m_window;