NOISSUE squish.

5 files changed, 483 insertions, 542 deletions

diff --git a/api/logic/CMakeLists.txt b/api/logic/CMakeLists.txt
index 387b3428..f0b2d979 100644
--- a/api/logic/CMakeLists.txt
+++ b/api/logic/CMakeLists.txt
@@ -16,8 +16,6 @@ set(CORE_SOURCES
     LoggedProcess.cpp
     MessageLevel.cpp
     MessageLevel.h
-    FolderInstanceProvider.h
-    FolderInstanceProvider.cpp
     BaseVersion.h
     BaseInstance.h
     BaseInstance.cpp
diff --git a/api/logic/FolderInstanceProvider.cpp b/api/logic/FolderInstanceProvider.cpp
deleted file mode 100644
index 4c44836d..00000000
--- a/api/logic/FolderInstanceProvider.cpp
+++ /dev/null
@@ -1,429 +0,0 @@
-#include "FolderInstanceProvider.h"
-#include "settings/INISettingsObject.h"
-#include "FileSystem.h"
-#include "minecraft/MinecraftInstance.h"
-#include "minecraft/legacy/LegacyInstance.h"
-#include "NullInstance.h"
-#include "ExponentialSeries.h"
-#include "WatchLock.h"
-
-
-#include <QDir>
-#include <QDirIterator>
-#include <QFileSystemWatcher>
-#include <QJsonDocument>
-#include <QJsonObject>
-#include <QJsonArray>
-#include <QUuid>
-#include <QTimer>
-
-const static int GROUP_FILE_FORMAT_VERSION = 1;
-
-FolderInstanceProvider::FolderInstanceProvider(SettingsObjectPtr settings, const QString& instDir)
-    : m_globalSettings(settings)
-{
-    // Create aand normalize path
-    if (!QDir::current().exists(instDir))
-    {
-        QDir::current().mkpath(instDir);
-    }
-    // NOTE: canonicalPath requires the path to exist. Do not move this above the creation block!
-    m_instDir = QDir(instDir).canonicalPath();
-    m_watcher = new QFileSystemWatcher(this);
-    connect(m_watcher, &QFileSystemWatcher::directoryChanged, this, &FolderInstanceProvider::instanceDirContentsChanged);
-    m_watcher->addPath(m_instDir);
-}
-
-QList< InstanceId > FolderInstanceProvider::discoverInstances()
-{
-    qDebug() << "Discovering instances in" << m_instDir;
-    QList<InstanceId> out;
-    QDirIterator iter(m_instDir, QDir::Dirs | QDir::NoDot | QDir::NoDotDot | QDir::Readable | QDir::Hidden, QDirIterator::FollowSymlinks);
-    while (iter.hasNext())
-    {
-        QString subDir = iter.next();
-        QFileInfo dirInfo(subDir);
-        if (!QFileInfo(FS::PathCombine(subDir, "instance.cfg")).exists())
-            continue;
-        // if it is a symlink, ignore it if it goes to the instance folder
-        if(dirInfo.isSymLink())
-        {
-            QFileInfo targetInfo(dirInfo.symLinkTarget());
-            QFileInfo instDirInfo(m_instDir);
-            if(targetInfo.canonicalPath() == instDirInfo.canonicalFilePath())
-            {
-                qDebug() << "Ignoring symlink" << subDir << "that leads into the instances folder";
-                continue;
-            }
-        }
-        auto id = dirInfo.fileName();
-        out.append(id);
-        qDebug() << "Found instance ID" << id;
-    }
-    instanceSet = out.toSet();
-    m_instancesProbed = true;
-    return out;
-}
-
-InstancePtr FolderInstanceProvider::loadInstance(const InstanceId& id)
-{
-    if(!m_groupsLoaded)
-    {
-        loadGroupList();
-    }
-
-    auto instanceRoot = FS::PathCombine(m_instDir, id);
-    auto instanceSettings = std::make_shared<INISettingsObject>(FS::PathCombine(instanceRoot, "instance.cfg"));
-    InstancePtr inst;
-
-    instanceSettings->registerSetting("InstanceType", "Legacy");
-
-    QString inst_type = instanceSettings->get("InstanceType").toString();
-
-    if (inst_type == "OneSix" || inst_type == "Nostalgia")
-    {
-        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));
-    }
-    inst->init();
-    auto iter = groupMap.find(id);
-    if (iter != groupMap.end())
-    {
-        inst->setGroupInitial((*iter));
-    }
-    connect(inst.get(), &BaseInstance::groupChanged, this, &FolderInstanceProvider::groupChanged);
-    qDebug() << "Loaded instance " << inst->name() << " from " << inst->instanceRoot();
-    return inst;
-}
-
-void FolderInstanceProvider::saveGroupList()
-{
-    qDebug() << "Will save group list now.";
-    if(!m_instancesProbed)
-    {
-        qDebug() << "Group saving prevented because we don't know the full list of instances yet.";
-        return;
-    }
-    WatchLock foo(m_watcher, m_instDir);
-    QString groupFileName = m_instDir + "/instgroups.json";
-    QMap<QString, QSet<QString>> reverseGroupMap;
-    for (auto iter = groupMap.begin(); iter != groupMap.end(); iter++)
-    {
-        QString id = iter.key();
-        QString group = iter.value();
-        if (group.isEmpty())
-            continue;
-        if(!instanceSet.contains(id))
-        {
-            qDebug() << "Skipping saving missing instance" << id << "to groups list.";
-            continue;
-        }
-
-        if (!reverseGroupMap.count(group))
-        {
-            QSet<QString> set;
-            set.insert(id);
-            reverseGroupMap[group] = set;
-        }
-        else
-        {
-            QSet<QString> &set = reverseGroupMap[group];
-            set.insert(id);
-        }
-    }
-    QJsonObject toplevel;
-    toplevel.insert("formatVersion", QJsonValue(QString("1")));
-    QJsonObject groupsArr;
-    for (auto iter = reverseGroupMap.begin(); iter != reverseGroupMap.end(); iter++)
-    {
-        auto list = iter.value();
-        auto name = iter.key();
-        QJsonObject groupObj;
-        QJsonArray instanceArr;
-        groupObj.insert("hidden", QJsonValue(QString("false")));
-        for (auto item : list)
-        {
-            instanceArr.append(QJsonValue(item));
-        }
-        groupObj.insert("instances", instanceArr);
-        groupsArr.insert(name, groupObj);
-    }
-    toplevel.insert("groups", groupsArr);
-    QJsonDocument doc(toplevel);
-    try
-    {
-        FS::write(groupFileName, doc.toJson());
-        qDebug() << "Group list saved.";
-    }
-    catch (const FS::FileSystemException &e)
-    {
-        qCritical() << "Failed to write instance group file :" << e.cause();
-    }
-}
-
-void FolderInstanceProvider::loadGroupList()
-{
-    qDebug() << "Will load group list now.";
-    QSet<QString> groupSet;
-
-    QString groupFileName = m_instDir + "/instgroups.json";
-
-    // if there's no group file, fail
-    if (!QFileInfo(groupFileName).exists())
-        return;
-
-    QByteArray jsonData;
-    try
-    {
-        jsonData = FS::read(groupFileName);
-    }
-    catch (const FS::FileSystemException &e)
-    {
-        qCritical() << "Failed to read instance group file :" << e.cause();
-        return;
-    }
-
-    QJsonParseError error;
-    QJsonDocument jsonDoc = QJsonDocument::fromJson(jsonData, &error);
-
-    // if the json was bad, fail
-    if (error.error != QJsonParseError::NoError)
-    {
-        qCritical() << QString("Failed to parse instance group file: %1 at offset %2")
-                            .arg(error.errorString(), QString::number(error.offset))
-                            .toUtf8();
-        return;
-    }
-
-    // if the root of the json wasn't an object, fail
-    if (!jsonDoc.isObject())
-    {
-        qWarning() << "Invalid group file. Root entry should be an object.";
-        return;
-    }
-
-    QJsonObject rootObj = jsonDoc.object();
-
-    // Make sure the format version matches, otherwise fail.
-    if (rootObj.value("formatVersion").toVariant().toInt() != GROUP_FILE_FORMAT_VERSION)
-        return;
-
-    // Get the groups. if it's not an object, fail
-    if (!rootObj.value("groups").isObject())
-    {
-        qWarning() << "Invalid group list JSON: 'groups' should be an object.";
-        return;
-    }
-
-    groupMap.clear();
-
-    // Iterate through all the groups.
-    QJsonObject groupMapping = rootObj.value("groups").toObject();
-    for (QJsonObject::iterator iter = groupMapping.begin(); iter != groupMapping.end(); iter++)
-    {
-        QString groupName = iter.key();
-
-        // If not an object, complain and skip to the next one.
-        if (!iter.value().isObject())
-        {
-            qWarning() << QString("Group '%1' in the group list should "
-                                   "be an object.")
-                               .arg(groupName)
-                               .toUtf8();
-            continue;
-        }
-
-        QJsonObject groupObj = iter.value().toObject();
-        if (!groupObj.value("instances").isArray())
-        {
-            qWarning() << QString("Group '%1' in the group list is invalid. "
-                                   "It should contain an array "
-                                   "called 'instances'.")
-                               .arg(groupName)
-                               .toUtf8();
-            continue;
-        }
-
-        // keep a list/set of groups for choosing
-        groupSet.insert(groupName);
-
-        // Iterate through the list of instances in the group.
-        QJsonArray instancesArray = groupObj.value("instances").toArray();
-
-        for (QJsonArray::iterator iter2 = instancesArray.begin(); iter2 != instancesArray.end();
-             iter2++)
-        {
-            groupMap[(*iter2).toString()] = groupName;
-        }
-    }
-    m_groupsLoaded = true;
-    emit groupsChanged(groupSet);
-    qDebug() << "Group list loaded.";
-}
-
-void FolderInstanceProvider::groupChanged()
-{
-    // save the groups. save all of them.
-    auto instance = (BaseInstance *) QObject::sender();
-    auto id = instance->id();
-    groupMap[id] = instance->group();
-    emit groupsChanged({instance->group()});
-    saveGroupList();
-}
-
-
-void FolderInstanceProvider::instanceDirContentsChanged(const QString& path)
-{
-    Q_UNUSED(path);
-    emit instancesChanged();
-}
-
-void FolderInstanceProvider::on_InstFolderChanged(const Setting &setting, QVariant value)
-{
-    QString newInstDir = QDir(value.toString()).canonicalPath();
-    if(newInstDir != m_instDir)
-    {
-        if(m_groupsLoaded)
-        {
-            saveGroupList();
-        }
-        m_instDir = newInstDir;
-        m_groupsLoaded = false;
-        emit instancesChanged();
-    }
-}
-
-class InstanceStaging : public Task
-{
-Q_OBJECT
-    const unsigned minBackoff = 1;
-    const unsigned maxBackoff = 16;
-public:
-    InstanceStaging (
-        FolderInstanceProvider * parent,
-        Task * child,
-        const QString & stagingPath,
-        const QString& instanceName,
-        const QString& groupName )
-    : backoff(minBackoff, maxBackoff)
-    {
-        m_parent = parent;
-        m_child.reset(child);
-        connect(child, &Task::succeeded, this, &InstanceStaging::childSucceded);
-        connect(child, &Task::failed, this, &InstanceStaging::childFailed);
-        connect(child, &Task::status, this, &InstanceStaging::setStatus);
-        connect(child, &Task::progress, this, &InstanceStaging::setProgress);
-        m_instanceName = instanceName;
-        m_groupName = groupName;
-        m_stagingPath = stagingPath;
-        m_backoffTimer.setSingleShot(true);
-        connect(&m_backoffTimer, &QTimer::timeout, this, &InstanceStaging::childSucceded);
-    }
-
-    virtual ~InstanceStaging() {};
-
-protected:
-    virtual void executeTask() override
-    {
-        m_child->start();
-    }
-    QStringList warnings() const override
-    {
-        return m_child->warnings();
-    }
-
-private slots:
-    void childSucceded()
-    {
-        unsigned sleepTime = backoff();
-        if(m_parent->commitStagedInstance(m_stagingPath, m_instanceName, m_groupName))
-        {
-            emitSucceeded();
-            return;
-        }
-        // we actually failed, retry?
-        if(sleepTime == maxBackoff)
-        {
-            emitFailed(tr("Failed to commit instance, even after multiple retries. It is being blocked by something."));
-            return;
-        }
-        qDebug() << "Failed to commit instance" << m_instanceName << "Initiating backoff:" << sleepTime;
-        m_backoffTimer.start(sleepTime * 500);
-    }
-    void childFailed(const QString & reason)
-    {
-        m_parent->destroyStagingPath(m_stagingPath);
-        emitFailed(reason);
-    }
-
-private:
-    /*
-     * WHY: the whole reason why this uses an exponential backoff retry scheme is antivirus on Windows.
-     * Basically, it starts messing things up while MultiMC is extracting/creating instances
-     * and causes that horrible failure that is NTFS to lock files in place because they are open.
-     */
-    ExponentialSeries backoff;
-    QString m_stagingPath;
-    FolderInstanceProvider * m_parent;
-    unique_qobject_ptr<Task> m_child;
-    QString m_instanceName;
-    QString m_groupName;
-    QTimer m_backoffTimer;
-};
-
-#include "InstanceTask.h"
-Task * FolderInstanceProvider::wrapInstanceTask(InstanceTask * task)
-{
-    auto stagingPath = getStagedInstancePath();
-    task->setStagingPath(stagingPath);
-    task->setParentSettings(m_globalSettings);
-    return new InstanceStaging(this, task, stagingPath, task->name(), task->group());
-}
-
-QString FolderInstanceProvider::getStagedInstancePath()
-{
-    QString key = QUuid::createUuid().toString();
-    QString relPath = FS::PathCombine("_MMC_TEMP/" , key);
-    QDir rootPath(m_instDir);
-    auto path = FS::PathCombine(m_instDir, relPath);
-    if(!rootPath.mkpath(relPath))
-    {
-        return QString();
-    }
-    return path;
-}
-
-bool FolderInstanceProvider::commitStagedInstance(const QString& path, const QString& instanceName, const QString& groupName)
-{
-    QDir dir;
-    QString instID = FS::DirNameFromString(instanceName, m_instDir);
-    {
-        WatchLock lock(m_watcher, m_instDir);
-        QString destination = FS::PathCombine(m_instDir, instID);
-        if(!dir.rename(path, destination))
-        {
-            qWarning() << "Failed to move" << path << "to" << destination;
-            return false;
-        }
-        groupMap[instID] = groupName;
-        instanceSet.insert(instID);
-        emit groupsChanged({groupName});
-        emit instancesChanged();
-    }
-    saveGroupList();
-    return true;
-}
-
-bool FolderInstanceProvider::destroyStagingPath(const QString& keyPath)
-{
-    return FS::deletePath(keyPath);
-}
-
-#include "FolderInstanceProvider.moc"
diff --git a/api/logic/FolderInstanceProvider.h b/api/logic/FolderInstanceProvider.h
deleted file mode 100644
index ce5337c1..00000000
--- a/api/logic/FolderInstanceProvider.h
+++ /dev/null
@@ -1,86 +0,0 @@
-#pragma once
-
-
-#include <QObject>
-#include <QString>
-#include <QMap>
-#include "BaseInstance.h"
-#include "settings/SettingsObject.h"
-
-#include "multimc_logic_export.h"
-
-class QFileSystemWatcher;
-class InstanceTask;
-using InstanceId = QString;
-using GroupId = QString;
-using InstanceLocator = std::pair<InstancePtr, int>;
-
-enum class InstCreateError
-{
-    NoCreateError = 0,
-    NoSuchVersion,
-    UnknownCreateError,
-    InstExists,
-    CantCreateDir
-};
-
-class MULTIMC_LOGIC_EXPORT FolderInstanceProvider : public QObject
-{
-    Q_OBJECT
-public:
-    FolderInstanceProvider(SettingsObjectPtr settings, const QString & instDir);
-    virtual ~FolderInstanceProvider() = default;
-
-public:
-    /// used by InstanceList to @return a list of plausible IDs to probe for
-    QList<InstanceId> discoverInstances();
-
-    /// used by InstanceList to (re)load an instance with the given @id.
-    InstancePtr loadInstance(const InstanceId& id);
-
-    // Wrap an instance creation task in some more task machinery and make it ready to be used
-    Task * wrapInstanceTask(InstanceTask * task);
-
-    /**
-     * Create a new empty staging area for instance creation and @return a path/key top commit it later.
-     * Used by instance manipulation tasks.
-     */
-    QString getStagedInstancePath();
-    /**
-     * Commit the staging area given by @keyPath to the provider - used when creation succeeds.
-     * Used by instance manipulation tasks.
-     */
-    bool commitStagedInstance(const QString & keyPath, const QString& instanceName, const QString & groupName);
-    /**
-     * Destroy a previously created staging area given by @keyPath - used when creation fails.
-     * Used by instance manipulation tasks.
-     */
-    bool destroyStagingPath(const QString & keyPath);
-
-signals:
-    // Emit this when the list of provided instances changed
-    void instancesChanged();
-    // Emit when the set of groups your provider supplies changes.
-    void groupsChanged(QSet<QString> groups);
-
-
-public slots:
-    void on_InstFolderChanged(const Setting &setting, QVariant value);
-
-private slots:
-    void instanceDirContentsChanged(const QString &path);
-    void groupChanged();
-
-private: /* methods */
-    void loadGroupList();
-    void saveGroupList();
-
-private: /* data */
-    SettingsObjectPtr m_globalSettings;
-    QString m_instDir;
-    QFileSystemWatcher * m_watcher;
-    QMap<InstanceId, GroupId> groupMap;
-    QSet<InstanceId> instanceSet;
-    bool m_groupsLoaded = false;
-    bool m_instancesProbed = false;
-};
diff --git a/api/logic/InstanceList.cpp b/api/logic/InstanceList.cpp
index 7e2c03a9..616d2887 100644
--- a/api/logic/InstanceList.cpp
+++ b/api/logic/InstanceList.cpp
@@ -14,23 +14,50 @@
  */
 
 #include <QDir>
+#include <QDirIterator>
 #include <QSet>
 #include <QFile>
 #include <QThread>
 #include <QTextStream>
 #include <QXmlStreamReader>
+#include <QTimer>
 #include <QDebug>
+#include <QFileSystemWatcher>
+#include <QUuid>
+#include <QJsonArray>
+#include <QJsonDocument>
 
 #include "InstanceList.h"
 #include "BaseInstance.h"
-
-#include "FolderInstanceProvider.h"
+#include "InstanceTask.h"
+#include "settings/INISettingsObject.h"
+#include "minecraft/legacy/LegacyInstance.h"
+#include "NullInstance.h"
+#include "minecraft/MinecraftInstance.h"
 #include "FileSystem.h"
+#include "ExponentialSeries.h"
+#include "WatchLock.h"
+
+const static int GROUP_FILE_FORMAT_VERSION = 1;
 
-InstanceList::InstanceList(QObject *parent)
-    : QAbstractListModel(parent)
+InstanceList::InstanceList(SettingsObjectPtr settings, const QString & instDir, QObject *parent)
+    : QAbstractListModel(parent), m_globalSettings(settings)
 {
     resumeWatch();
+    // Create aand normalize path
+    if (!QDir::current().exists(instDir))
+    {
+        QDir::current().mkpath(instDir);
+    }
+
+    connect(this, &InstanceList::instancesChanged, this, &InstanceList::providerUpdated);
+    connect(this, &InstanceList::groupsChanged, this, &InstanceList::groupsPublished);
+
+    // NOTE: canonicalPath requires the path to exist. Do not move this above the creation block!
+    m_instDir = QDir(instDir).canonicalPath();
+    m_watcher = new QFileSystemWatcher(this);
+    connect(m_watcher, &QFileSystemWatcher::directoryChanged, this, &InstanceList::instanceDirContentsChanged);
+    m_watcher->addPath(m_instDir);
 }
 
 InstanceList::~InstanceList()
@@ -155,13 +182,44 @@ static QMap<InstanceId, InstanceLocator> getIdMapping(const QList<InstancePtr> &
     return out;
 }
 
+QList< InstanceId > InstanceList::discoverInstances()
+{
+    qDebug() << "Discovering instances in" << m_instDir;
+    QList<InstanceId> out;
+    QDirIterator iter(m_instDir, QDir::Dirs | QDir::NoDot | QDir::NoDotDot | QDir::Readable | QDir::Hidden, QDirIterator::FollowSymlinks);
+    while (iter.hasNext())
+    {
+        QString subDir = iter.next();
+        QFileInfo dirInfo(subDir);
+        if (!QFileInfo(FS::PathCombine(subDir, "instance.cfg")).exists())
+            continue;
+        // if it is a symlink, ignore it if it goes to the instance folder
+        if(dirInfo.isSymLink())
+        {
+            QFileInfo targetInfo(dirInfo.symLinkTarget());
+            QFileInfo instDirInfo(m_instDir);
+            if(targetInfo.canonicalPath() == instDirInfo.canonicalFilePath())
+            {
+                qDebug() << "Ignoring symlink" << subDir << "that leads into the instances folder";
+                continue;
+            }
+        }
+        auto id = dirInfo.fileName();
+        out.append(id);
+        qDebug() << "Found instance ID" << id;
+    }
+    instanceSet = out.toSet();
+    m_instancesProbed = true;
+    return out;
+}
+
 InstanceList::InstListError InstanceList::loadList()
 {
     auto existingIds = getIdMapping(m_instances);
 
     QList<InstancePtr> newList;
 
-    for(auto & id: m_provider->discoverInstances())
+    for(auto & id: discoverInstances())
     {
         if(existingIds.contains(id))
         {
@@ -171,7 +229,7 @@ InstanceList::InstListError InstanceList::loadList()
         }
         else
         {
-            InstancePtr instPtr = m_provider->loadInstance(id);
+            InstancePtr instPtr = loadInstance(id);
             if(instPtr)
             {
                 newList.append(instPtr);
@@ -275,12 +333,6 @@ void InstanceList::suspendWatch()
 
 void InstanceList::providerUpdated()
 {
-    auto provider = dynamic_cast<FolderInstanceProvider *>(QObject::sender());
-    if(!provider)
-    {
-        qWarning() << "InstanceList::providerUpdated triggered by a non-provider";
-        return;
-    }
     m_dirty = true;
     if(m_watchLevel == 1)
     {
@@ -293,13 +345,6 @@ void InstanceList::groupsPublished(QSet<QString> newGroups)
     m_groups.unite(newGroups);
 }
 
-void InstanceList::addInstanceProvider(FolderInstanceProvider* provider)
-{
-    connect(provider, &FolderInstanceProvider::instancesChanged, this, &InstanceList::providerUpdated);
-    connect(provider, &FolderInstanceProvider::groupsChanged, this, &InstanceList::groupsPublished);
-    m_provider = provider;
-}
-
 InstancePtr InstanceList::getInstanceById(QString instId) const
 {
     if(instId.isEmpty())
@@ -340,3 +385,364 @@ void InstanceList::propertiesChanged(BaseInstance *inst)
         emit dataChanged(index(i), index(i));
     }
 }
+
+InstancePtr InstanceList::loadInstance(const InstanceId& id)
+{
+    if(!m_groupsLoaded)
+    {
+        loadGroupList();
+    }
+
+    auto instanceRoot = FS::PathCombine(m_instDir, id);
+    auto instanceSettings = std::make_shared<INISettingsObject>(FS::PathCombine(instanceRoot, "instance.cfg"));
+    InstancePtr inst;
+
+    instanceSettings->registerSetting("InstanceType", "Legacy");
+
+    QString inst_type = instanceSettings->get("InstanceType").toString();
+
+    if (inst_type == "OneSix" || inst_type == "Nostalgia")
+    {
+        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));
+    }
+    inst->init();
+    auto iter = groupMap.find(id);
+    if (iter != groupMap.end())
+    {
+        inst->setGroupInitial((*iter));
+    }
+    connect(inst.get(), &BaseInstance::groupChanged, this, &InstanceList::groupChanged);
+    qDebug() << "Loaded instance " << inst->name() << " from " << inst->instanceRoot();
+    return inst;
+}
+
+void InstanceList::saveGroupList()
+{
+    qDebug() << "Will save group list now.";
+    if(!m_instancesProbed)
+    {
+        qDebug() << "Group saving prevented because we don't know the full list of instances yet.";
+        return;
+    }
+    WatchLock foo(m_watcher, m_instDir);
+    QString groupFileName = m_instDir + "/instgroups.json";
+    QMap<QString, QSet<QString>> reverseGroupMap;
+    for (auto iter = groupMap.begin(); iter != groupMap.end(); iter++)
+    {
+        QString id = iter.key();
+        QString group = iter.value();
+        if (group.isEmpty())
+            continue;
+        if(!instanceSet.contains(id))
+        {
+            qDebug() << "Skipping saving missing instance" << id << "to groups list.";
+            continue;
+        }
+
+        if (!reverseGroupMap.count(group))
+        {
+            QSet<QString> set;
+            set.insert(id);
+            reverseGroupMap[group] = set;
+        }
+        else
+        {
+            QSet<QString> &set = reverseGroupMap[group];
+            set.insert(id);
+        }
+    }
+    QJsonObject toplevel;
+    toplevel.insert("formatVersion", QJsonValue(QString("1")));
+    QJsonObject groupsArr;
+    for (auto iter = reverseGroupMap.begin(); iter != reverseGroupMap.end(); iter++)
+    {
+        auto list = iter.value();
+        auto name = iter.key();
+        QJsonObject groupObj;
+        QJsonArray instanceArr;
+        groupObj.insert("hidden", QJsonValue(QString("false")));
+        for (auto item : list)
+        {
+            instanceArr.append(QJsonValue(item));
+        }
+        groupObj.insert("instances", instanceArr);
+        groupsArr.insert(name, groupObj);
+    }
+    toplevel.insert("groups", groupsArr);
+    QJsonDocument doc(toplevel);
+    try
+    {
+        FS::write(groupFileName, doc.toJson());
+        qDebug() << "Group list saved.";
+    }
+    catch (const FS::FileSystemException &e)
+    {
+        qCritical() << "Failed to write instance group file :" << e.cause();
+    }
+}
+
+void InstanceList::loadGroupList()
+{
+    qDebug() << "Will load group list now.";
+    QSet<QString> groupSet;
+
+    QString groupFileName = m_instDir + "/instgroups.json";
+
+    // if there's no group file, fail
+    if (!QFileInfo(groupFileName).exists())
+        return;
+
+    QByteArray jsonData;
+    try
+    {
+        jsonData = FS::read(groupFileName);
+    }
+    catch (const FS::FileSystemException &e)
+    {
+        qCritical() << "Failed to read instance group file :" << e.cause();
+        return;
+    }
+
+    QJsonParseError error;
+    QJsonDocument jsonDoc = QJsonDocument::fromJson(jsonData, &error);
+
+    // if the json was bad, fail
+    if (error.error != QJsonParseError::NoError)
+    {
+        qCritical() << QString("Failed to parse instance group file: %1 at offset %2")
+                            .arg(error.errorString(), QString::number(error.offset))
+                            .toUtf8();
+        return;
+    }
+
+    // if the root of the json wasn't an object, fail
+    if (!jsonDoc.isObject())
+    {
+        qWarning() << "Invalid group file. Root entry should be an object.";
+        return;
+    }
+
+    QJsonObject rootObj = jsonDoc.object();
+
+    // Make sure the format version matches, otherwise fail.
+    if (rootObj.value("formatVersion").toVariant().toInt() != GROUP_FILE_FORMAT_VERSION)
+        return;
+
+    // Get the groups. if it's not an object, fail
+    if (!rootObj.value("groups").isObject())
+    {
+        qWarning() << "Invalid group list JSON: 'groups' should be an object.";
+        return;
+    }
+
+    groupMap.clear();
+
+    // Iterate through all the groups.
+    QJsonObject groupMapping = rootObj.value("groups").toObject();
+    for (QJsonObject::iterator iter = groupMapping.begin(); iter != groupMapping.end(); iter++)
+    {
+        QString groupName = iter.key();
+
+        // If not an object, complain and skip to the next one.
+        if (!iter.value().isObject())
+        {
+            qWarning() << QString("Group '%1' in the group list should "
+                                   "be an object.")
+                               .arg(groupName)
+                               .toUtf8();
+            continue;
+        }
+
+        QJsonObject groupObj = iter.value().toObject();
+        if (!groupObj.value("instances").isArray())
+        {
+            qWarning() << QString("Group '%1' in the group list is invalid. "
+                                   "It should contain an array "
+                                   "called 'instances'.")
+                               .arg(groupName)
+                               .toUtf8();
+            continue;
+        }
+
+        // keep a list/set of groups for choosing
+        groupSet.insert(groupName);
+
+        // Iterate through the list of instances in the group.
+        QJsonArray instancesArray = groupObj.value("instances").toArray();
+
+        for (QJsonArray::iterator iter2 = instancesArray.begin(); iter2 != instancesArray.end(); iter2++)
+        {
+            groupMap[(*iter2).toString()] = groupName;
+        }
+    }
+    m_groupsLoaded = true;
+    emit groupsChanged(groupSet);
+    qDebug() << "Group list loaded.";
+}
+
+void InstanceList::groupChanged()
+{
+    // save the groups. save all of them.
+    auto instance = (BaseInstance *) QObject::sender();
+    auto id = instance->id();
+    groupMap[id] = instance->group();
+    emit groupsChanged({instance->group()});
+    saveGroupList();
+}
+
+
+void InstanceList::instanceDirContentsChanged(const QString& path)
+{
+    Q_UNUSED(path);
+    emit instancesChanged();
+}
+
+void InstanceList::on_InstFolderChanged(const Setting &setting, QVariant value)
+{
+    QString newInstDir = QDir(value.toString()).canonicalPath();
+    if(newInstDir != m_instDir)
+    {
+        if(m_groupsLoaded)
+        {
+            saveGroupList();
+        }
+        m_instDir = newInstDir;
+        m_groupsLoaded = false;
+        emit instancesChanged();
+    }
+}
+
+class InstanceStaging : public Task
+{
+Q_OBJECT
+    const unsigned minBackoff = 1;
+    const unsigned maxBackoff = 16;
+public:
+    InstanceStaging (
+        InstanceList * parent,
+        Task * child,
+        const QString & stagingPath,
+        const QString& instanceName,
+        const QString& groupName )
+    : backoff(minBackoff, maxBackoff)
+    {
+        m_parent = parent;
+        m_child.reset(child);
+        connect(child, &Task::succeeded, this, &InstanceStaging::childSucceded);
+        connect(child, &Task::failed, this, &InstanceStaging::childFailed);
+        connect(child, &Task::status, this, &InstanceStaging::setStatus);
+        connect(child, &Task::progress, this, &InstanceStaging::setProgress);
+        m_instanceName = instanceName;
+        m_groupName = groupName;
+        m_stagingPath = stagingPath;
+        m_backoffTimer.setSingleShot(true);
+        connect(&m_backoffTimer, &QTimer::timeout, this, &InstanceStaging::childSucceded);
+    }
+
+    virtual ~InstanceStaging() {};
+
+protected:
+    virtual void executeTask() override
+    {
+        m_child->start();
+    }
+    QStringList warnings() const override
+    {
+        return m_child->warnings();
+    }
+
+private slots:
+    void childSucceded()
+    {
+        unsigned sleepTime = backoff();
+        if(m_parent->commitStagedInstance(m_stagingPath, m_instanceName, m_groupName))
+        {
+            emitSucceeded();
+            return;
+        }
+        // we actually failed, retry?
+        if(sleepTime == maxBackoff)
+        {
+            emitFailed(tr("Failed to commit instance, even after multiple retries. It is being blocked by something."));
+            return;
+        }
+        qDebug() << "Failed to commit instance" << m_instanceName << "Initiating backoff:" << sleepTime;
+        m_backoffTimer.start(sleepTime * 500);
+    }
+    void childFailed(const QString & reason)
+    {
+        m_parent->destroyStagingPath(m_stagingPath);
+        emitFailed(reason);
+    }
+
+private:
+    /*
+     * WHY: the whole reason why this uses an exponential backoff retry scheme is antivirus on Windows.
+     * Basically, it starts messing things up while MultiMC is extracting/creating instances
+     * and causes that horrible failure that is NTFS to lock files in place because they are open.
+     */
+    ExponentialSeries backoff;
+    QString m_stagingPath;
+    InstanceList * m_parent;
+    unique_qobject_ptr<Task> m_child;
+    QString m_instanceName;
+    QString m_groupName;
+    QTimer m_backoffTimer;
+};
+
+Task * InstanceList::wrapInstanceTask(InstanceTask * task)
+{
+    auto stagingPath = getStagedInstancePath();
+    task->setStagingPath(stagingPath);
+    task->setParentSettings(m_globalSettings);
+    return new InstanceStaging(this, task, stagingPath, task->name(), task->group());
+}
+
+QString InstanceList::getStagedInstancePath()
+{
+    QString key = QUuid::createUuid().toString();
+    QString relPath = FS::PathCombine("_MMC_TEMP/" , key);
+    QDir rootPath(m_instDir);
+    auto path = FS::PathCombine(m_instDir, relPath);
+    if(!rootPath.mkpath(relPath))
+    {
+        return QString();
+    }
+    return path;
+}
+
+bool InstanceList::commitStagedInstance(const QString& path, const QString& instanceName, const QString& groupName)
+{
+    QDir dir;
+    QString instID = FS::DirNameFromString(instanceName, m_instDir);
+    {
+        WatchLock lock(m_watcher, m_instDir);
+        QString destination = FS::PathCombine(m_instDir, instID);
+        if(!dir.rename(path, destination))
+        {
+            qWarning() << "Failed to move" << path << "to" << destination;
+            return false;
+        }
+        groupMap[instID] = groupName;
+        instanceSet.insert(instID);
+        emit groupsChanged({groupName});
+        emit instancesChanged();
+    }
+    saveGroupList();
+    return true;
+}
+
+bool InstanceList::destroyStagingPath(const QString& keyPath)
+{
+    return FS::deletePath(keyPath);
+}
+
+#include "InstanceList.moc"
\ No newline at end of file
diff --git a/api/logic/InstanceList.h b/api/logic/InstanceList.h
index 14b80a78..a487a7ca 100644
--- a/api/logic/InstanceList.h
+++ b/api/logic/InstanceList.h
@@ -21,18 +21,33 @@
 #include <QList>
 
 #include "BaseInstance.h"
-#include "FolderInstanceProvider.h"
 
 #include "multimc_logic_export.h"
 
 #include "QObjectPtr.h"
 
+class QFileSystemWatcher;
+class InstanceTask;
+using InstanceId = QString;
+using GroupId = QString;
+using InstanceLocator = std::pair<InstancePtr, int>;
+
+enum class InstCreateError
+{
+    NoCreateError = 0,
+    NoSuchVersion,
+    UnknownCreateError,
+    InstExists,
+    CantCreateDir
+};
+
+
 class MULTIMC_LOGIC_EXPORT InstanceList : public QAbstractListModel
 {
     Q_OBJECT
 
 public:
-    explicit InstanceList(QObject *parent = 0);
+    explicit InstanceList(SettingsObjectPtr settings, const QString & instDir, QObject *parent = 0);
     virtual ~InstanceList();
 
 public:
@@ -71,8 +86,6 @@ public:
     InstListError loadList();
     void saveNow();
 
-    /// Add an instance provider. Takes ownership of it. Should only be done before the first load.
-    void addInstanceProvider(FolderInstanceProvider * provider);
 
     InstancePtr getInstanceById(QString id) const;
     QModelIndex getInstanceIndexById(const QString &id) const;
@@ -81,24 +94,63 @@ public:
     void deleteGroup(const GroupId & name);
     void deleteInstance(const InstanceId & id);
 
+    // Wrap an instance creation task in some more task machinery and make it ready to be used
+    Task * wrapInstanceTask(InstanceTask * task);
+
+    /**
+     * Create a new empty staging area for instance creation and @return a path/key top commit it later.
+     * Used by instance manipulation tasks.
+     */
+    QString getStagedInstancePath();
+
+    /**
+     * Commit the staging area given by @keyPath to the provider - used when creation succeeds.
+     * Used by instance manipulation tasks.
+     */
+    bool commitStagedInstance(const QString & keyPath, const QString& instanceName, const QString & groupName);
+
+    /**
+     * Destroy a previously created staging area given by @keyPath - used when creation fails.
+     * Used by instance manipulation tasks.
+     */
+    bool destroyStagingPath(const QString & keyPath);
+
 signals:
     void dataIsInvalid();
+    void instancesChanged();
+    void groupsChanged(QSet<QString> groups);
+
+public slots:
+    void on_InstFolderChanged(const Setting &setting, QVariant value);
 
 private slots:
     void propertiesChanged(BaseInstance *inst);
     void groupsPublished(QSet<QString>);
     void providerUpdated();
+    void instanceDirContentsChanged(const QString &path);
+    void groupChanged();
 
 private:
     int getInstIndex(BaseInstance *inst) const;
     void suspendWatch();
     void resumeWatch();
     void add(const QList<InstancePtr> &list);
+    void loadGroupList();
+    void saveGroupList();
+    QList<InstanceId> discoverInstances();
+    InstancePtr loadInstance(const InstanceId& id);
 
-protected:
+private:
     int m_watchLevel = 0;
     bool m_dirty = false;
     QList<InstancePtr> m_instances;
     QSet<QString> m_groups;
-    FolderInstanceProvider * m_provider;
+
+    SettingsObjectPtr m_globalSettings;
+    QString m_instDir;
+    QFileSystemWatcher * m_watcher;
+    QMap<InstanceId, GroupId> groupMap;
+    QSet<InstanceId> instanceSet;
+    bool m_groupsLoaded = false;
+    bool m_instancesProbed = false;
 };