NOISSUE Add back Legacy for migration purposes

14 files changed, 821 insertions, 4 deletions

diff --git a/api/logic/CMakeLists.txt b/api/logic/CMakeLists.txt
index 909e51a9..5cd80166 100644
--- a/api/logic/CMakeLists.txt
+++ b/api/logic/CMakeLists.txt
@@ -228,6 +228,10 @@ set(MINECRAFT_SOURCES
 	minecraft/launch/LauncherPartLaunch.h
 	minecraft/launch/PrintInstanceInfo.cpp
 	minecraft/launch/PrintInstanceInfo.h
+	minecraft/legacy/LegacyModList.h
+	minecraft/legacy/LegacyModList.cpp
+	minecraft/legacy/LegacyInstance.h
+	minecraft/legacy/LegacyInstance.cpp
 	minecraft/GradleSpecifier.h
 	minecraft/MinecraftInstance.cpp
 	minecraft/MinecraftInstance.h
diff --git a/api/logic/Env.cpp b/api/logic/Env.cpp
index e2abda49..cf321af2 100644
--- a/api/logic/Env.cpp
+++ b/api/logic/Env.cpp
@@ -19,8 +19,6 @@ struct Env::Private
 	shared_qobject_ptr<HttpMetaCache> m_metacache;
 	std::shared_ptr<IIconList> m_iconlist;
 	shared_qobject_ptr<Meta::Index> m_metadataIndex;
-	// FIXME: replace with mojang format LWJGL in meta store
-	std::shared_ptr<LWJGLVersionList> m_lwjgllist;
 	QString m_jarsPath;
 };
 
diff --git a/api/logic/Env.h b/api/logic/Env.h
index 3dadc58e..276d762d 100644
--- a/api/logic/Env.h
+++ b/api/logic/Env.h
@@ -13,7 +13,6 @@ class QNetworkAccessManager;
 class HttpMetaCache;
 class BaseVersionList;
 class BaseVersion;
-class LWJGLVersionList;
 
 namespace Meta
 {
diff --git a/api/logic/FolderInstanceProvider.cpp b/api/logic/FolderInstanceProvider.cpp
index a0fbd46a..25e9bb84 100644
--- a/api/logic/FolderInstanceProvider.cpp
+++ b/api/logic/FolderInstanceProvider.cpp
@@ -2,6 +2,7 @@
 #include "settings/INISettingsObject.h"
 #include "FileSystem.h"
 #include "minecraft/MinecraftInstance.h"
+#include "minecraft/legacy/LegacyInstance.h"
 #include "NullInstance.h"
 
 #include <QDir>
@@ -90,6 +91,10 @@ InstancePtr FolderInstanceProvider::loadInstance(const InstanceId& id)
 	{
 		inst.reset(new MinecraftInstance(m_globalSettings, instanceSettings, instanceRoot));
 	}
+	else if (inst_type == "Legacy")
+	{
+		inst.reset(new LegacyInstance(m_globalSettings, instanceSettings, instanceRoot));
+	}
 	else
 	{
 		inst.reset(new NullInstance(m_globalSettings, instanceSettings, instanceRoot));
diff --git a/api/logic/minecraft/ModList.h b/api/logic/minecraft/ModList.h
index f9b6b1c5..8cdd2d9a 100644
--- a/api/logic/minecraft/ModList.h
+++ b/api/logic/minecraft/ModList.h
@@ -24,6 +24,7 @@
 
 #include "multimc_logic_export.h"
 
+class LegacyInstance;
 class BaseInstance;
 class QFileSystemWatcher;
 
diff --git a/api/logic/minecraft/legacy/LegacyInstance.cpp b/api/logic/minecraft/legacy/LegacyInstance.cpp
new file mode 100644
index 00000000..532e8307
--- /dev/null
+++ b/api/logic/minecraft/legacy/LegacyInstance.cpp
@@ -0,0 +1,313 @@
+/* Copyright 2013-2017 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 <QFileInfo>
+#include <minecraft/launch/LauncherPartLaunch.h>
+#include <QDir>
+#include <settings/Setting.h>
+
+#include "LegacyInstance.h"
+
+#include "minecraft/legacy/LegacyModList.h"
+#include "minecraft/ModList.h"
+#include "minecraft/WorldList.h"
+#include <MMCZip.h>
+#include <FileSystem.h>
+
+LegacyInstance::LegacyInstance(SettingsObjectPtr globalSettings, SettingsObjectPtr settings, const QString &rootDir)
+	: BaseInstance(globalSettings, settings, rootDir)
+{
+	settings->registerSetting("NeedsRebuild", true);
+	settings->registerSetting("ShouldUpdate", false);
+	settings->registerSetting("JarVersion", "Unknown");
+	settings->registerSetting("IntendedJarVersion", "");
+	/*
+	 * custom base jar has no default. it is determined in code... see the accessor methods for
+	 *it
+	 *
+	 * for instances that DO NOT have the CustomBaseJar setting (legacy instances),
+	 * [.]minecraft/bin/mcbackup.jar is the default base jar
+	 */
+	settings->registerSetting("UseCustomBaseJar", true);
+	settings->registerSetting("CustomBaseJar", "");
+}
+
+QString LegacyInstance::baseJar() const
+{
+	bool customJar = m_settings->get("UseCustomBaseJar").toBool();
+	if (customJar)
+	{
+		return customBaseJar();
+	}
+	else
+		return defaultBaseJar();
+}
+
+QString LegacyInstance::customBaseJar() const
+{
+	QString value = m_settings->get("CustomBaseJar").toString();
+	if (value.isNull() || value.isEmpty())
+	{
+		return defaultCustomBaseJar();
+	}
+	return value;
+}
+
+bool LegacyInstance::shouldUseCustomBaseJar() const
+{
+	return m_settings->get("UseCustomBaseJar").toBool();
+}
+
+
+shared_qobject_ptr<Task> LegacyInstance::createUpdateTask()
+{
+	return nullptr;
+}
+
+/*
+class LegacyJarModTask : public Task
+{
+	//Q_OBJECT
+public:
+	explicit LegacyJarModTask(std::shared_ptr<LegacyInstance> inst) : Task(nullptr), m_inst(inst)
+	{
+	}
+	virtual void executeTask()
+	{
+		if (!m_inst->shouldRebuild())
+		{
+			emitSucceeded();
+			return;
+		}
+
+		// Get the mod list
+		auto modList = m_inst->getJarMods();
+
+		QFileInfo runnableJar(m_inst->runnableJar());
+		QFileInfo baseJar(m_inst->baseJar());
+		bool base_is_custom = m_inst->shouldUseCustomBaseJar();
+
+		// Nothing to do if there are no jar mods to install, no backup and just the mc jar
+		if (base_is_custom)
+		{
+			// yes, this can happen if the instance only has the runnable jar and not the base jar
+			// it *could* be assumed that such an instance is vanilla, but that wouldn't be safe
+			// because that's not something mmc4 guarantees
+			if (runnableJar.isFile() && !baseJar.exists() && modList.empty())
+			{
+				m_inst->setShouldRebuild(false);
+				emitSucceeded();
+				return;
+			}
+
+			setStatus(tr("Installing mods: Backing up minecraft.jar ..."));
+			if (!baseJar.exists() && !QFile::copy(runnableJar.filePath(), baseJar.filePath()))
+			{
+				emitFailed("It seems both the active and base jar are gone. A fresh base jar will "
+						"be used on next run.");
+				m_inst->setShouldRebuild(true);
+				m_inst->setShouldUpdate(true);
+				m_inst->setShouldUseCustomBaseJar(false);
+				return;
+			}
+		}
+
+		if (!baseJar.exists())
+		{
+			emitFailed("The base jar " + baseJar.filePath() + " does not exist");
+			return;
+		}
+
+		if (runnableJar.exists() && !QFile::remove(runnableJar.filePath()))
+		{
+			emitFailed("Failed to delete old minecraft.jar");
+			return;
+		}
+
+		setStatus(tr("Installing mods: Opening minecraft.jar ..."));
+
+		QString outputJarPath = runnableJar.filePath();
+		QString inputJarPath = baseJar.filePath();
+
+		if(!MMCZip::createModdedJar(inputJarPath, outputJarPath, modList))
+		{
+			emitFailed(tr("Failed to create the custom Minecraft jar file."));
+			return;
+		}
+		m_inst->setShouldRebuild(false);
+		// inst->UpdateVersion(true);
+		emitSucceeded();
+		return;
+
+	}
+	std::shared_ptr<LegacyInstance> m_inst;
+};
+*/
+
+std::shared_ptr<LegacyModList> LegacyInstance::jarModList() const
+{
+	if (!jar_mod_list)
+	{
+		auto list = new LegacyModList(jarModsDir(), modListFile());
+		jar_mod_list.reset(list);
+	}
+	jar_mod_list->update();
+	return jar_mod_list;
+}
+
+QList<Mod> LegacyInstance::getJarMods() const
+{
+	return jarModList()->allMods();
+}
+
+QString LegacyInstance::minecraftRoot() const
+{
+	QFileInfo mcDir(FS::PathCombine(instanceRoot(), "minecraft"));
+	QFileInfo dotMCDir(FS::PathCombine(instanceRoot(), ".minecraft"));
+
+	if (dotMCDir.exists() && !mcDir.exists())
+		return dotMCDir.filePath();
+	else
+		return mcDir.filePath();
+}
+
+QString LegacyInstance::binRoot() const
+{
+	return FS::PathCombine(minecraftRoot(), "bin");
+}
+
+QString LegacyInstance::jarModsDir() const
+{
+	return FS::PathCombine(instanceRoot(), "instMods");
+}
+
+QString LegacyInstance::libDir() const
+{
+	return FS::PathCombine(minecraftRoot(), "lib");
+}
+
+QString LegacyInstance::savesDir() const
+{
+	return FS::PathCombine(minecraftRoot(), "saves");
+}
+
+QString LegacyInstance::loaderModsDir() const
+{
+	return FS::PathCombine(minecraftRoot(), "mods");
+}
+
+QString LegacyInstance::coreModsDir() const
+{
+	return FS::PathCombine(minecraftRoot(), "coremods");
+}
+
+QString LegacyInstance::resourceDir() const
+{
+	return FS::PathCombine(minecraftRoot(), "resources");
+}
+QString LegacyInstance::texturePacksDir() const
+{
+	return FS::PathCombine(minecraftRoot(), "texturepacks");
+}
+
+QString LegacyInstance::runnableJar() const
+{
+	return FS::PathCombine(binRoot(), "minecraft.jar");
+}
+
+QString LegacyInstance::modListFile() const
+{
+	return FS::PathCombine(instanceRoot(), "modlist");
+}
+
+QString LegacyInstance::instanceConfigFolder() const
+{
+	return FS::PathCombine(minecraftRoot(), "config");
+}
+
+bool LegacyInstance::shouldRebuild() const
+{
+	return m_settings->get("NeedsRebuild").toBool();
+}
+
+QString LegacyInstance::currentVersionId() const
+{
+	return m_settings->get("JarVersion").toString();
+}
+
+QString LegacyInstance::intendedVersionId() const
+{
+	return m_settings->get("IntendedJarVersion").toString();
+}
+
+bool LegacyInstance::shouldUpdate() const
+{
+	QVariant var = settings()->get("ShouldUpdate");
+	if (!var.isValid() || var.toBool() == false)
+	{
+		return intendedVersionId() != currentVersionId();
+	}
+	return true;
+}
+
+QString LegacyInstance::defaultBaseJar() const
+{
+	return "versions/" + intendedVersionId() + "/" + intendedVersionId() + ".jar";
+}
+
+QString LegacyInstance::defaultCustomBaseJar() const
+{
+	return FS::PathCombine(binRoot(), "mcbackup.jar");
+}
+
+QString LegacyInstance::typeName() const
+{
+	return tr("Legacy");
+}
+
+QString LegacyInstance::getStatusbarDescription()
+{
+	return tr("Instance from previous versions.");
+}
+
+QStringList LegacyInstance::verboseDescription(AuthSessionPtr session)
+{
+	QStringList out;
+
+	auto alltraits = traits();
+	if(alltraits.size())
+	{
+		out << "Traits:";
+		for (auto trait : alltraits)
+		{
+			out << "  " + trait;
+		}
+		out << "";
+	}
+
+	QString windowParams;
+	if (settings()->get("LaunchMaximized").toBool())
+	{
+		out << "Window size: max (if available)";
+	}
+	else
+	{
+		auto width = settings()->get("MinecraftWinWidth").toInt();
+		auto height = settings()->get("MinecraftWinHeight").toInt();
+		out << "Window size: " + QString::number(width) + " x " + QString::number(height);
+	}
+	out << "";
+	return out;
+}
diff --git a/api/logic/minecraft/legacy/LegacyInstance.h b/api/logic/minecraft/legacy/LegacyInstance.h
new file mode 100644
index 00000000..9c5cedd3
--- /dev/null
+++ b/api/logic/minecraft/legacy/LegacyInstance.h
@@ -0,0 +1,128 @@
+/* Copyright 2013-2017 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include "BaseInstance.h"
+#include "minecraft/Mod.h"
+
+#include "multimc_logic_export.h"
+
+class ModList;
+class LegacyModList;
+class Task;
+/*
+ * WHY: Legacy instances - from MultiMC 3 and 4 - are here only to provide a way to upgrade them to the current format.
+ */
+class MULTIMC_LOGIC_EXPORT LegacyInstance : public BaseInstance
+{
+	Q_OBJECT
+public:
+
+	explicit LegacyInstance(SettingsObjectPtr globalSettings, SettingsObjectPtr settings, const QString &rootDir);
+
+	virtual void init() override {};
+
+	/// Path to the instance's minecraft.jar
+	QString runnableJar() const;
+
+	//! Path to the instance's modlist file.
+	QString modListFile() const;
+
+	////// Directories //////
+	QString libDir() const;
+	QString savesDir() const;
+	QString texturePacksDir() const;
+	QString jarModsDir() const;
+	QString loaderModsDir() const;
+	QString coreModsDir() const;
+	QString resourceDir() const;
+	virtual QString instanceConfigFolder() const override;
+	QString minecraftRoot() const; // Path to the instance's minecraft directory.
+	QString binRoot() const; // Path to the instance's minecraft bin directory.
+
+	/// Get the curent base jar of this instance. By default, it's the
+	/// versions/$version/$version.jar
+	QString baseJar() const;
+
+	/// the default base jar of this instance
+	QString defaultBaseJar() const;
+	/// the default custom base jar of this instance
+	QString defaultCustomBaseJar() const;
+
+	/*!
+	 * Whether or not custom base jar is used
+	 */
+	bool shouldUseCustomBaseJar() const;
+
+	/*!
+	 * The value of the custom base jar
+	 */
+	QString customBaseJar() const;
+
+	std::shared_ptr<LegacyModList> jarModList() const;
+	QList<Mod> getJarMods() const;
+
+	/*!
+	 * Whether or not the instance's minecraft.jar needs to be rebuilt.
+	 * If this is true, when the instance launches, its jar mods will be
+	 * re-added to a fresh minecraft.jar file.
+	 */
+	bool shouldRebuild() const;
+
+	QString currentVersionId() const;
+	QString intendedVersionId() const;
+
+	QSet<QString> traits() override
+	{
+		return {"legacy-instance", "texturepacks"};
+	};
+
+	virtual bool shouldUpdate() const;
+	virtual shared_qobject_ptr<Task> createUpdateTask() override;
+
+	virtual QString typeName() const override;
+
+	bool canExport() const override
+	{
+		return false;
+	}
+	std::shared_ptr<LaunchTask> createLaunchTask(AuthSessionPtr account) override
+	{
+		return nullptr;
+	}
+	IPathMatcher::Ptr getLogFileMatcher() override
+	{
+		return nullptr;
+	}
+	QString getLogFileRoot() override
+	{
+		return minecraftRoot();
+	}
+
+	QString getStatusbarDescription() override;
+	QStringList verboseDescription(AuthSessionPtr session) override;
+
+	QProcessEnvironment createEnvironment() override
+	{
+		return QProcessEnvironment();
+	}
+	QMap<QString, QString> getVariables() const override
+	{
+		return {};
+	}
+protected:
+	mutable std::shared_ptr<LegacyModList> jar_mod_list;
+};
diff --git a/api/logic/minecraft/legacy/LegacyModList.cpp b/api/logic/minecraft/legacy/LegacyModList.cpp
new file mode 100644
index 00000000..061752e0
--- /dev/null
+++ b/api/logic/minecraft/legacy/LegacyModList.cpp
@@ -0,0 +1,171 @@
+/* Copyright 2013-2017 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 "LegacyModList.h"
+#include <FileSystem.h>
+#include <QString>
+#include <QDebug>
+
+LegacyModList::LegacyModList(const QString &dir, const QString &list_file)
+	: m_dir(dir), m_list_file(list_file)
+{
+	FS::ensureFolderPathExists(m_dir.absolutePath());
+	m_dir.setFilter(QDir::Readable | QDir::NoDotAndDotDot | QDir::Files | QDir::Dirs |
+					QDir::NoSymLinks);
+	m_dir.setSorting(QDir::Name | QDir::IgnoreCase | QDir::LocaleAware);
+}
+
+	struct OrderItem
+	{
+		QString id;
+		bool enabled = false;
+	};
+	typedef QList<OrderItem> OrderList;
+
+static void internalSort(QList<Mod> &what)
+{
+	auto predicate = [](const Mod &left, const Mod &right)
+	{
+		if (left.name() == right.name())
+		{
+			return left.mmc_id().localeAwareCompare(right.mmc_id()) < 0;
+		}
+		return left.name().localeAwareCompare(right.name()) < 0;
+	};
+	std::sort(what.begin(), what.end(), predicate);
+}
+
+static OrderList readListFile(const QString &m_list_file)
+{
+	OrderList itemList;
+	if (m_list_file.isNull() || m_list_file.isEmpty())
+		return itemList;
+
+	QFile textFile(m_list_file);
+	if (!textFile.open(QIODevice::ReadOnly | QIODevice::Text))
+		return OrderList();
+
+	QTextStream textStream;
+	textStream.setAutoDetectUnicode(true);
+	textStream.setDevice(&textFile);
+	while (true)
+	{
+		QString line = textStream.readLine();
+		if (line.isNull() || line.isEmpty())
+			break;
+		else
+		{
+			OrderItem it;
+			it.enabled = !line.endsWith(".disabled");
+			if (!it.enabled)
+			{
+				line.chop(9);
+			}
+			it.id = line;
+			itemList.append(it);
+		}
+	}
+	textFile.close();
+	return itemList;
+}
+
+bool LegacyModList::update()
+{
+	if (!m_dir.exists() || !m_dir.isReadable())
+		return false;
+
+	QList<Mod> orderedMods;
+	QList<Mod> newMods;
+	m_dir.refresh();
+	auto folderContents = m_dir.entryInfoList();
+	bool orderOrStateChanged = false;
+
+	// first, process the ordered items (if any)
+	OrderList listOrder = readListFile(m_list_file);
+	for (auto item : listOrder)
+	{
+		QFileInfo infoEnabled(m_dir.filePath(item.id));
+		QFileInfo infoDisabled(m_dir.filePath(item.id + ".disabled"));
+		int idxEnabled = folderContents.indexOf(infoEnabled);
+		int idxDisabled = folderContents.indexOf(infoDisabled);
+		bool isEnabled;
+		// if both enabled and disabled versions are present, it's a special case...
+		if (idxEnabled >= 0 && idxDisabled >= 0)
+		{
+			// we only process the one we actually have in the order file.
+			// and exactly as we have it.
+			// THIS IS A CORNER CASE
+			isEnabled = item.enabled;
+		}
+		else
+		{
+			// only one is present.
+			// we pick the one that we found.
+			// we assume the mod was enabled/disabled by external means
+			isEnabled = idxEnabled >= 0;
+		}
+		int idx = isEnabled ? idxEnabled : idxDisabled;
+		QFileInfo &info = isEnabled ? infoEnabled : infoDisabled;
+		// if the file from the index file exists
+		if (idx != -1)
+		{
+			// remove from the actual folder contents list
+			folderContents.takeAt(idx);
+			// append the new mod
+			orderedMods.append(Mod(info));
+			if (isEnabled != item.enabled)
+				orderOrStateChanged = true;
+		}
+		else
+		{
+			orderOrStateChanged = true;
+		}
+	}
+	// if there are any untracked files...
+	if (folderContents.size())
+	{
+		// the order surely changed!
+		for (auto entry : folderContents)
+		{
+			newMods.append(Mod(entry));
+		}
+		internalSort(newMods);
+		orderedMods.append(newMods);
+		orderOrStateChanged = true;
+	}
+	// otherwise, if we were already tracking some mods
+	else if (mods.size())
+	{
+		// if the number doesn't match, order changed.
+		if (mods.size() != orderedMods.size())
+			orderOrStateChanged = true;
+		// if it does match, compare the mods themselves
+		else
+			for (int i = 0; i < mods.size(); i++)
+			{
+				if (!mods[i].strongCompare(orderedMods[i]))
+				{
+					orderOrStateChanged = true;
+					break;
+				}
+			}
+	}
+	mods.swap(orderedMods);
+	if (orderOrStateChanged && !m_list_file.isEmpty())
+	{
+		qDebug() << "Mod list " << m_list_file << " changed!";
+	}
+	return true;
+}
diff --git a/api/logic/minecraft/legacy/LegacyModList.h b/api/logic/minecraft/legacy/LegacyModList.h
new file mode 100644
index 00000000..3fe90ac3
--- /dev/null
+++ b/api/logic/minecraft/legacy/LegacyModList.h
@@ -0,0 +1,56 @@
+/* Copyright 2013-2017 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <QList>
+#include <QString>
+#include <QDir>
+
+#include "minecraft/Mod.h"
+
+#include "multimc_logic_export.h"
+
+class LegacyInstance;
+class BaseInstance;
+
+/**
+ * A legacy mod list.
+ * Backed by a folder.
+ */
+class MULTIMC_LOGIC_EXPORT LegacyModList
+{
+public:
+
+	LegacyModList(const QString &dir, const QString &list_file = QString());
+
+	/// Reloads the mod list and returns true if the list changed.
+	bool update();
+
+	QDir dir()
+	{
+		return m_dir;
+	}
+
+	const QList<Mod> & allMods()
+	{
+		return mods;
+	}
+
+protected:
+	QDir m_dir;
+	QString m_list_file;
+	QList<Mod> mods;
+};
diff --git a/application/CMakeLists.txt b/application/CMakeLists.txt
index 70cb1e93..17e19b58 100644
--- a/application/CMakeLists.txt
+++ b/application/CMakeLists.txt
@@ -131,6 +131,8 @@ SET(MULTIMC_SOURCES
 	pages/ScreenshotsPage.h
 	pages/OtherLogsPage.cpp
 	pages/OtherLogsPage.h
+	pages/LegacyUpgradePage.cpp
+	pages/LegacyUpgradePage.h
 	pages/WorldListPage.cpp
 	pages/WorldListPage.h
 
@@ -229,7 +231,7 @@ SET(MULTIMC_SOURCES
 
 ######## UIs ########
 SET(MULTIMC_UIS
-	# Option pages
+	# Instance pages
 	pages/VersionPage.ui
 	pages/ModFolderPage.ui
 	pages/LogPage.ui
@@ -237,6 +239,7 @@ SET(MULTIMC_UIS
 	pages/NotesPage.ui
 	pages/ScreenshotsPage.ui
 	pages/OtherLogsPage.ui
+	pages/LegacyUpgradePage.ui
 	pages/WorldListPage.ui
 
 	# Global settings pages
diff --git a/application/InstancePageProvider.h b/application/InstancePageProvider.h
index ac5306c0..3b361e3e 100644
--- a/application/InstancePageProvider.h
+++ b/application/InstancePageProvider.h
@@ -1,5 +1,6 @@
 #pragma once
 #include "minecraft/MinecraftInstance.h"
+#include "minecraft/legacy/LegacyInstance.h"
 #include <FileSystem.h>
 #include "pages/BasePage.h"
 #include "pages/LogPage.h"
@@ -12,6 +13,7 @@
 #include "pages/InstanceSettingsPage.h"
 #include "pages/OtherLogsPage.h"
 #include "pages/BasePageProvider.h"
+#include "pages/LegacyUpgradePage.h"
 #include "pages/WorldListPage.h"
 
 
@@ -44,6 +46,11 @@ public:
 			values.append(new ScreenshotsPage(FS::PathCombine(onesix->minecraftRoot(), "screenshots")));
 			values.append(new InstanceSettingsPage(onesix.get()));
 		}
+		std::shared_ptr<LegacyInstance> legacy = std::dynamic_pointer_cast<LegacyInstance>(inst);
+		if(legacy)
+		{
+			values.append(new LegacyUpgradePage(legacy.get()));
+		}
 		auto logMatcher = inst->getLogFileMatcher();
 		if(logMatcher)
 		{
diff --git a/application/pages/LegacyUpgradePage.cpp b/application/pages/LegacyUpgradePage.cpp
new file mode 100644
index 00000000..14cb916d
--- /dev/null
+++ b/application/pages/LegacyUpgradePage.cpp
@@ -0,0 +1,25 @@
+#include "LegacyUpgradePage.h"
+#include "ui_LegacyUpgradePage.h"
+
+#include "minecraft/legacy/LegacyInstance.h"
+
+LegacyUpgradePage::LegacyUpgradePage(LegacyInstance *inst, QWidget *parent)
+	: QWidget(parent), ui(new Ui::LegacyUpgradePage), m_inst(inst)
+{
+	ui->setupUi(this);
+}
+
+LegacyUpgradePage::~LegacyUpgradePage()
+{
+	delete ui;
+}
+
+void LegacyUpgradePage::on_upgradeButton_clicked()
+{
+	// now what?
+}
+
+bool LegacyUpgradePage::shouldDisplay() const
+{
+	return !m_inst->isRunning();
+}
diff --git a/application/pages/LegacyUpgradePage.h b/application/pages/LegacyUpgradePage.h
new file mode 100644
index 00000000..4731bb82
--- /dev/null
+++ b/application/pages/LegacyUpgradePage.h
@@ -0,0 +1,60 @@
+/* Copyright 2013-2017 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <QWidget>
+
+#include "minecraft/legacy/LegacyInstance.h"
+#include "pages/BasePage.h"
+#include <MultiMC.h>
+
+namespace Ui
+{
+class LegacyUpgradePage;
+}
+
+class LegacyUpgradePage : public QWidget, public BasePage
+{
+	Q_OBJECT
+
+public:
+	explicit LegacyUpgradePage(LegacyInstance *inst, QWidget *parent = 0);
+	virtual ~LegacyUpgradePage();
+	virtual QString displayName() const override
+	{
+		return tr("Upgrade");
+	}
+	virtual QIcon icon() const override
+	{
+		return MMC->getThemedIcon("checkupdate");
+	}
+	virtual QString id() const override
+	{
+		return "upgrade";
+	}
+	virtual QString helpPage() const override
+	{
+		return "Legacy-upgrade";
+	}
+	virtual bool shouldDisplay() const override;
+private
+slots:
+	void on_upgradeButton_clicked();
+
+private:
+	Ui::LegacyUpgradePage *ui;
+	LegacyInstance *m_inst;
+};
diff --git a/application/pages/LegacyUpgradePage.ui b/application/pages/LegacyUpgradePage.ui
new file mode 100644
index 00000000..124a0ce9
--- /dev/null
+++ b/application/pages/LegacyUpgradePage.ui
@@ -0,0 +1,47 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<ui version="4.0">
+ <class>LegacyUpgradePage</class>
+ <widget class="QWidget" name="LegacyUpgradePage">
+  <property name="geometry">
+   <rect>
+    <x>0</x>
+    <y>0</y>
+    <width>546</width>
+    <height>405</height>
+   </rect>
+  </property>
+  <layout class="QVBoxLayout" name="verticalLayout_5">
+   <property name="leftMargin">
+    <number>0</number>
+   </property>
+   <property name="topMargin">
+    <number>0</number>
+   </property>
+   <property name="rightMargin">
+    <number>0</number>
+   </property>
+   <property name="bottomMargin">
+    <number>0</number>
+   </property>
+   <item>
+    <widget class="QTextBrowser" name="textBrowser">
+     <property name="html">
+      <string>&lt;html&gt;&lt;body&gt;&lt;h1&gt;Upgrade is required&lt;/h1&gt;&lt;p&gt;MultiMC now supports old Minecraft versions and all the required features in the new (OneSix) instance format. As a consequence, the old (Legacy) format has been entirely disabled and old instances need to be upgraded.&lt;/p&gt;&lt;p&gt;The upgrade will create a new instance with the same contents as the current one, in the new format. The original instance will remain untouched, in case anything goes wrong in the process.&lt;/p&gt;&lt;p&gt;Please report any issues on our &lt;a href=&quot;https://github.com/MultiMC/MultiMC5/issues&quot;&gt;github issues page&lt;/a&gt;.&lt;/p&gt;&lt;/body&gt;&lt;/html&gt;</string>
+     </property>
+     <property name="openExternalLinks">
+      <bool>true</bool>
+     </property>
+    </widget>
+   </item>
+   <item>
+    <widget class="QCommandLinkButton" name="upgradeButton">
+     <property name="text">
+      <string>Upgrade the instance</string>
+     </property>
+    </widget>
+   </item>
+  </layout>
+ </widget>
+ <resources/>
+ <connections/>
+</ui>