NOISSUE Various changes from multiauth that are unrelated to it

47 files changed, 2398 insertions, 319 deletions

diff --git a/logic/AbstractCommonModel.cpp b/logic/AbstractCommonModel.cpp
new file mode 100644
index 00000000..71d75829
--- /dev/null
+++ b/logic/AbstractCommonModel.cpp
@@ -0,0 +1,133 @@
+/* Copyright 2015 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 "AbstractCommonModel.h"
+
+BaseAbstractCommonModel::BaseAbstractCommonModel(const Qt::Orientation orientation, QObject *parent)
+	: QAbstractListModel(parent), m_orientation(orientation)
+{
+}
+
+int BaseAbstractCommonModel::rowCount(const QModelIndex &parent) const
+{
+	return m_orientation == Qt::Horizontal ? entryCount() : size();
+}
+int BaseAbstractCommonModel::columnCount(const QModelIndex &parent) const
+{
+	return m_orientation == Qt::Horizontal ? size() : entryCount();
+}
+QVariant BaseAbstractCommonModel::data(const QModelIndex &index, int role) const
+{
+	if (!hasIndex(index.row(), index.column(), index.parent()))
+	{
+		return QVariant();
+	}
+	const int i = m_orientation == Qt::Horizontal ? index.column() : index.row();
+	const int entry = m_orientation == Qt::Horizontal ? index.row() : index.column();
+	return formatData(i, role, get(i, entry, role));
+}
+QVariant BaseAbstractCommonModel::headerData(int section, Qt::Orientation orientation, int role) const
+{
+	if (orientation != m_orientation && role == Qt::DisplayRole)
+	{
+		return entryTitle(section);
+	}
+	else
+	{
+		return QVariant();
+	}
+}
+bool BaseAbstractCommonModel::setData(const QModelIndex &index, const QVariant &value, int role)
+{
+	const int i = m_orientation == Qt::Horizontal ? index.column() : index.row();
+	const int entry = m_orientation == Qt::Horizontal ? index.row() : index.column();
+	const bool result = set(i, entry, role, sanetizeData(i, role, value));
+	if (result)
+	{
+		emit dataChanged(index, index, QVector<int>() << role);
+	}
+	return result;
+}
+Qt::ItemFlags BaseAbstractCommonModel::flags(const QModelIndex &index) const
+{
+	if (!hasIndex(index.row(), index.column(), index.parent()))
+	{
+		return Qt::NoItemFlags;
+	}
+
+	const int entry = m_orientation == Qt::Horizontal ? index.row() : index.column();
+	if (canSet(entry))
+	{
+		return Qt::ItemIsEnabled | Qt::ItemIsSelectable | Qt::ItemIsEnabled;
+	}
+	else
+	{
+		return Qt::ItemIsEnabled | Qt::ItemIsSelectable;
+	}
+}
+
+void BaseAbstractCommonModel::notifyAboutToAddObject(const int at)
+{
+	if (m_orientation == Qt::Horizontal)
+	{
+		beginInsertColumns(QModelIndex(), at, at);
+	}
+	else
+	{
+		beginInsertRows(QModelIndex(), at, at);
+	}
+}
+void BaseAbstractCommonModel::notifyObjectAdded()
+{
+	if (m_orientation == Qt::Horizontal)
+	{
+		endInsertColumns();
+	}
+	else
+	{
+		endInsertRows();
+	}
+}
+void BaseAbstractCommonModel::notifyAboutToRemoveObject(const int at)
+{
+	if (m_orientation == Qt::Horizontal)
+	{
+		beginRemoveColumns(QModelIndex(), at, at);
+	}
+	else
+	{
+		beginRemoveRows(QModelIndex(), at, at);
+	}
+}
+void BaseAbstractCommonModel::notifyObjectRemoved()
+{
+	if (m_orientation == Qt::Horizontal)
+	{
+		endRemoveColumns();
+	}
+	else
+	{
+		endRemoveRows();
+	}
+}
+
+void BaseAbstractCommonModel::notifyBeginReset()
+{
+	beginResetModel();
+}
+void BaseAbstractCommonModel::notifyEndReset()
+{
+	endResetModel();
+}
diff --git a/logic/AbstractCommonModel.h b/logic/AbstractCommonModel.h
new file mode 100644
index 00000000..31b86a23
--- /dev/null
+++ b/logic/AbstractCommonModel.h
@@ -0,0 +1,462 @@
+/* Copyright 2015 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 <QAbstractListModel>
+#include <type_traits>
+#include <functional>
+#include <memory>
+
+class BaseAbstractCommonModel : public QAbstractListModel
+{
+	Q_OBJECT
+public:
+	explicit BaseAbstractCommonModel(const Qt::Orientation orientation, QObject *parent = nullptr);
+
+	// begin QAbstractItemModel interface
+	int rowCount(const QModelIndex &parent = QModelIndex()) const override;
+	int columnCount(const QModelIndex &parent = QModelIndex()) const override;
+	QVariant data(const QModelIndex &index, int role) const override;
+	QVariant headerData(int section, Qt::Orientation orientation, int role) const override;
+	bool setData(const QModelIndex &index, const QVariant &value, int role) override;
+	Qt::ItemFlags flags(const QModelIndex &index) const override;
+	// end QAbstractItemModel interface
+
+	virtual int size() const = 0;
+	virtual int entryCount() const = 0;
+
+	virtual QVariant formatData(const int index, int role, const QVariant &data) const { return data; }
+	virtual QVariant sanetizeData(const int index, int role, const QVariant &data) const { return data; }
+
+protected:
+	virtual QVariant get(const int index, const int entry, const int role) const = 0;
+	virtual bool set(const int index, const int entry, const int role, const QVariant &value) = 0;
+	virtual bool canSet(const int entry) const = 0;
+	virtual QString entryTitle(const int entry) const = 0;
+
+	void notifyAboutToAddObject(const int at);
+	void notifyObjectAdded();
+	void notifyAboutToRemoveObject(const int at);
+	void notifyObjectRemoved();
+	void notifyBeginReset();
+	void notifyEndReset();
+
+	const Qt::Orientation m_orientation;
+};
+
+template<typename Object>
+class AbstractCommonModel : public BaseAbstractCommonModel
+{
+public:
+	explicit AbstractCommonModel(const Qt::Orientation orientation)
+		: BaseAbstractCommonModel(orientation) {}
+	virtual ~AbstractCommonModel() {}
+
+	int size() const override { return m_objects.size(); }
+	int entryCount() const override { return m_entries.size(); }
+
+	void append(const Object &object)
+	{
+		notifyAboutToAddObject(size());
+		m_objects.append(object);
+		notifyObjectAdded();
+	}
+	void prepend(const Object &object)
+	{
+		notifyAboutToAddObject(0);
+		m_objects.prepend(object);
+		notifyObjectAdded();
+	}
+	void insert(const Object &object, const int index)
+	{
+		if (index >= size())
+		{
+			prepend(object);
+		}
+		else if (index <= 0)
+		{
+			append(object);
+		}
+		else
+		{
+			notifyAboutToAddObject(index);
+			m_objects.insert(index, object);
+			notifyObjectAdded();
+		}
+	}
+	void remove(const int index)
+	{
+		notifyAboutToRemoveObject(index);
+		m_objects.removeAt(index);
+		notifyObjectRemoved();
+	}
+	Object get(const int index) const
+	{
+		return m_objects.at(index);
+	}
+
+private:
+	friend class CommonModel;
+	QVariant get(const int index, const int entry, const int role) const override
+	{
+		if (m_entries.size() < entry || !m_entries[entry].second.contains(role))
+		{
+			return QVariant();
+		}
+		return m_entries[entry].second.value(role)->get(m_objects.at(index));
+	}
+	bool set(const int index, const int entry, const int role, const QVariant &value) override
+	{
+		if (m_entries.size() < entry || !m_entries[entry].second.contains(role))
+		{
+			return false;
+		}
+		IEntry *e = m_entries[entry].second.value(role);
+		if (!e->canSet())
+		{
+			return false;
+		}
+		e->set(m_objects[index], value);
+		return true;
+	}
+	bool canSet(const int entry) const override
+	{
+		if (m_entries.size() < entry || !m_entries[entry].second.contains(Qt::EditRole))
+		{
+			return false;
+		}
+		IEntry *e = m_entries[entry].second.value(Qt::EditRole);
+		return e->canSet();
+	}
+
+	QString entryTitle(const int entry) const override
+	{
+		return m_entries.at(entry).first;
+	}
+
+private:
+	struct IEntry
+	{
+		virtual ~IEntry() {}
+		virtual void set(Object &object, const QVariant &value) = 0;
+		virtual QVariant get(const Object &object) const = 0;
+		virtual bool canSet() const = 0;
+	};
+	template<typename T>
+	struct VariableEntry : public IEntry
+	{
+		typedef T (Object::*Member);
+
+		explicit VariableEntry(Member member)
+			: m_member(member) {}
+
+		void set(Object &object, const QVariant &value) override
+		{
+			object.*m_member = value.value<T>();
+		}
+		QVariant get(const Object &object) const override
+		{
+			return QVariant::fromValue<T>(object.*m_member);
+		}
+		bool canSet() const override { return true; }
+
+	private:
+		Member m_member;
+	};
+	template<typename T>
+	struct FunctionEntry : public IEntry
+	{
+		typedef T (Object::*Getter)() const;
+		typedef void (Object::*Setter)(T);
+
+		explicit FunctionEntry(Getter getter, Setter setter)
+			: m_getter(m_getter), m_setter(m_setter) {}
+
+		void set(Object &object, const QVariant &value) override
+		{
+			object.*m_setter(value.value<T>());
+		}
+		QVariant get(const Object &object) const override
+		{
+			return QVariant::fromValue<T>(object.*m_getter());
+		}
+		bool canSet() const override { return !!m_setter; }
+
+	private:
+		Getter m_getter;
+		Setter m_setter;
+	};
+
+	QList<Object> m_objects;
+	QVector<QPair<QString, QMap<int, IEntry *>>> m_entries;
+
+	void addEntryInternal(IEntry *e, const int entry, const int role)
+	{
+		if (m_entries.size() <= entry)
+		{
+			m_entries.resize(entry + 1);
+		}
+		m_entries[entry].second.insert(role, e);
+	}
+
+protected:
+	template<typename Getter, typename Setter>
+	typename std::enable_if<std::is_member_function_pointer<Getter>::value && std::is_member_function_pointer<Getter>::value, void>::type
+	addEntry(Getter getter, Setter setter, const int entry, const int role)
+	{
+		addEntryInternal(new FunctionEntry<typename std::result_of<Getter>::type>(getter, setter), entry, role);
+	}
+	template<typename Getter>
+	typename std::enable_if<std::is_member_function_pointer<Getter>::value, void>::type
+	addEntry(Getter getter, const int entry, const int role)
+	{
+		addEntryInternal(new FunctionEntry<typename std::result_of<Getter>::type>(getter, nullptr), entry, role);
+	}
+	template<typename T>
+	typename std::enable_if<!std::is_member_function_pointer<T (Object::*)>::value, void>::type
+	addEntry(T (Object::*member), const int entry, const int role)
+	{
+		addEntryInternal(new VariableEntry<T>(member), entry, role);
+	}
+
+	void setEntryTitle(const int entry, const QString &title)
+	{
+		m_entries[entry].first = title;
+	}
+};
+template<typename Object>
+class AbstractCommonModel<Object *> : public BaseAbstractCommonModel
+{
+public:
+	explicit AbstractCommonModel(const Qt::Orientation orientation)
+		: BaseAbstractCommonModel(orientation) {}
+	virtual ~AbstractCommonModel()
+	{
+		qDeleteAll(m_objects);
+	}
+
+	int size() const override { return m_objects.size(); }
+	int entryCount() const override { return m_entries.size(); }
+
+	void append(Object *object)
+	{
+		notifyAboutToAddObject(size());
+		m_objects.append(object);
+		notifyObjectAdded();
+	}
+	void prepend(Object *object)
+	{
+		notifyAboutToAddObject(0);
+		m_objects.prepend(object);
+		notifyObjectAdded();
+	}
+	void insert(Object *object, const int index)
+	{
+		if (index >= size())
+		{
+			prepend(object);
+		}
+		else if (index <= 0)
+		{
+			append(object);
+		}
+		else
+		{
+			notifyAboutToAddObject(index);
+			m_objects.insert(index, object);
+			notifyObjectAdded();
+		}
+	}
+	void remove(const int index)
+	{
+		notifyAboutToRemoveObject(index);
+		m_objects.removeAt(index);
+		notifyObjectRemoved();
+	}
+	Object *get(const int index) const
+	{
+		return m_objects.at(index);
+	}
+	int find(Object * const obj) const
+	{
+		return m_objects.indexOf(obj);
+	}
+
+	QList<Object *> getAll() const
+	{
+		return m_objects;
+	}
+
+private:
+	friend class CommonModel;
+	QVariant get(const int index, const int entry, const int role) const override
+	{
+		if (m_entries.size() < entry || !m_entries[entry].second.contains(role))
+		{
+			return QVariant();
+		}
+		return m_entries[entry].second.value(role)->get(m_objects.at(index));
+	}
+	bool set(const int index, const int entry, const int role, const QVariant &value) override
+	{
+		if (m_entries.size() < entry || !m_entries[entry].second.contains(role))
+		{
+			return false;
+		}
+		IEntry *e = m_entries[entry].second.value(role);
+		if (!e->canSet())
+		{
+			return false;
+		}
+		e->set(m_objects[index], value);
+		return true;
+	}
+	bool canSet(const int entry) const override
+	{
+		if (m_entries.size() < entry || !m_entries[entry].second.contains(Qt::EditRole))
+		{
+			return false;
+		}
+		IEntry *e = m_entries[entry].second.value(Qt::EditRole);
+		return e->canSet();
+	}
+
+	QString entryTitle(const int entry) const override
+	{
+		return m_entries.at(entry).first;
+	}
+
+private:
+	struct IEntry
+	{
+		virtual ~IEntry() {}
+		virtual void set(Object *object, const QVariant &value) = 0;
+		virtual QVariant get(Object *object) const = 0;
+		virtual bool canSet() const = 0;
+	};
+	template<typename T>
+	struct VariableEntry : public IEntry
+	{
+		typedef T (Object::*Member);
+
+		explicit VariableEntry(Member member)
+			: m_member(member) {}
+
+		void set(Object *object, const QVariant &value) override
+		{
+			object->*m_member = value.value<T>();
+		}
+		QVariant get(Object *object) const override
+		{
+			return QVariant::fromValue<T>(object->*m_member);
+		}
+		bool canSet() const override { return true; }
+
+	private:
+		Member m_member;
+	};
+	template<typename T>
+	struct FunctionEntry : public IEntry
+	{
+		typedef T (Object::*Getter)() const;
+		typedef void (Object::*Setter)(T);
+
+		explicit FunctionEntry(Getter getter, Setter setter)
+			: m_getter(getter), m_setter(setter) {}
+
+		void set(Object *object, const QVariant &value) override
+		{
+			(object->*m_setter)(value.value<T>());
+		}
+		QVariant get(Object *object) const override
+		{
+			return QVariant::fromValue<T>((object->*m_getter)());
+		}
+		bool canSet() const override { return !!m_setter; }
+
+	private:
+		Getter m_getter;
+		Setter m_setter;
+	};
+	template<typename T>
+	struct LambdaEntry : public IEntry
+	{
+		using Getter = std::function<T(Object *)>;
+
+		explicit LambdaEntry(Getter getter)
+			: m_getter(getter) {}
+
+		void set(Object *object, const QVariant &value) override {}
+		QVariant get(Object *object) const override
+		{
+			return QVariant::fromValue<T>(m_getter(object));
+		}
+		bool canSet() const override { return false; }
+
+	private:
+		Getter m_getter;
+	};
+
+	QList<Object *> m_objects;
+	QVector<QPair<QString, QMap<int, IEntry *>>> m_entries;
+
+	void addEntryInternal(IEntry *e, const int entry, const int role)
+	{
+		if (m_entries.size() <= entry)
+		{
+			m_entries.resize(entry + 1);
+		}
+		m_entries[entry].second.insert(role, e);
+	}
+
+protected:
+	template<typename Getter, typename Setter>
+	typename std::enable_if<std::is_member_function_pointer<Getter>::value && std::is_member_function_pointer<Getter>::value, void>::type
+	addEntry(const int entry, const int role, Getter getter, Setter setter)
+	{
+		addEntryInternal(new FunctionEntry<typename std::result_of<Getter>::type>(getter, setter), entry, role);
+	}
+	template<typename T>
+	typename std::enable_if<std::is_member_function_pointer<typename FunctionEntry<T>::Getter>::value, void>::type
+	addEntry(const int entry, const int role, typename FunctionEntry<T>::Getter getter)
+	{
+		addEntryInternal(new FunctionEntry<T>(getter, nullptr), entry, role);
+	}
+	template<typename T>
+	typename std::enable_if<!std::is_member_function_pointer<T (Object::*)>::value, void>::type
+	addEntry(const int entry, const int role, T (Object::*member))
+	{
+		addEntryInternal(new VariableEntry<T>(member), entry, role);
+	}
+	template<typename T>
+	void addEntry(const int entry, const int role, typename LambdaEntry<T>::Getter lambda)
+	{
+		addEntryInternal(new LambdaEntry<T>(lambda), entry, role);
+	}
+
+	void setEntryTitle(const int entry, const QString &title)
+	{
+		m_entries[entry].first = title;
+	}
+
+	void setAll(const QList<Object *> objects)
+	{
+		notifyBeginReset();
+		qDeleteAll(m_objects);
+		m_objects = objects;
+		notifyEndReset();
+	}
+};
diff --git a/logic/BaseConfigObject.cpp b/logic/BaseConfigObject.cpp
new file mode 100644
index 00000000..ff698ad0
--- /dev/null
+++ b/logic/BaseConfigObject.cpp
@@ -0,0 +1,119 @@
+/* Copyright 2015 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 "BaseConfigObject.h"
+
+#include <QTimer>
+#include <QSaveFile>
+#include <QFile>
+#include <QCoreApplication>
+#include <QDebug>
+
+#include "Exception.h"
+
+BaseConfigObject::BaseConfigObject(const QString &filename)
+	: m_filename(filename)
+{
+	m_saveTimer = new QTimer;
+	m_saveTimer->setSingleShot(true);
+	// cppcheck-suppress pureVirtualCall
+	QObject::connect(m_saveTimer, &QTimer::timeout, [this](){saveNow();});
+	setSaveTimeout(250);
+
+	m_initialReadTimer = new QTimer;
+	m_initialReadTimer->setSingleShot(true);
+	QObject::connect(m_initialReadTimer, &QTimer::timeout, [this]()
+	{
+		loadNow();
+		m_initialReadTimer->deleteLater();
+		m_initialReadTimer = 0;
+	});
+	m_initialReadTimer->start(0);
+
+	// cppcheck-suppress pureVirtualCall
+	m_appQuitConnection = QObject::connect(qApp, &QCoreApplication::aboutToQuit, [this](){saveNow();});
+}
+BaseConfigObject::~BaseConfigObject()
+{
+	delete m_saveTimer;
+	if (m_initialReadTimer)
+	{
+		delete m_initialReadTimer;
+	}
+	QObject::disconnect(m_appQuitConnection);
+}
+
+void BaseConfigObject::setSaveTimeout(int msec)
+{
+	m_saveTimer->setInterval(msec);
+}
+
+void BaseConfigObject::scheduleSave()
+{
+	m_saveTimer->stop();
+	m_saveTimer->start();
+}
+void BaseConfigObject::saveNow()
+{
+	if (m_saveTimer->isActive())
+	{
+		m_saveTimer->stop();
+	}
+	if (m_disableSaving)
+	{
+		return;
+	}
+
+	QSaveFile file(m_filename);
+	if (!file.open(QFile::WriteOnly))
+	{
+		qWarning() << "Couldn't open" << m_filename << "for writing:" << file.errorString();
+		return;
+	}
+	// cppcheck-suppress pureVirtualCall
+	file.write(doSave());
+
+	if (!file.commit())
+	{
+		qCritical() << "Unable to commit the file" << file.fileName() << ":" << file.errorString();
+		file.cancelWriting();
+	}
+}
+void BaseConfigObject::loadNow()
+{
+	if (m_saveTimer->isActive())
+	{
+		saveNow();
+	}
+
+	QFile file(m_filename);
+	if (!file.exists())
+	{
+		return;
+	}
+	if (!file.open(QFile::ReadOnly))
+	{
+		qWarning() << "Couldn't open" << m_filename << "for reading:" << file.errorString();
+		return;
+	}
+	try
+	{
+		doLoad(file.readAll());
+	}
+	catch (Exception &e)
+	{
+		qWarning() << "Error loading" << m_filename << ":" << e.cause();
+	}
+}
diff --git a/logic/BaseConfigObject.h b/logic/BaseConfigObject.h
new file mode 100644
index 00000000..1c96b3d1
--- /dev/null
+++ b/logic/BaseConfigObject.h
@@ -0,0 +1,50 @@
+/* Copyright 2015 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 <QObject>
+
+class QTimer;
+
+class BaseConfigObject
+{
+public:
+	void setSaveTimeout(int msec);
+
+protected:
+	explicit BaseConfigObject(const QString &filename);
+	virtual ~BaseConfigObject();
+
+	// cppcheck-suppress pureVirtualCall
+	virtual QByteArray doSave() const = 0;
+	virtual void doLoad(const QByteArray &data) = 0;
+
+	void setSavingDisabled(bool savingDisabled) { m_disableSaving = savingDisabled; }
+
+	QString fileName() const { return m_filename; }
+
+public:
+	void scheduleSave();
+	void saveNow();
+	void loadNow();
+
+private:
+	QTimer *m_saveTimer;
+	QTimer *m_initialReadTimer;
+	QString m_filename;
+	QMetaObject::Connection m_appQuitConnection;
+	bool m_disableSaving = false;
+};
diff --git a/logic/CMakeLists.txt b/logic/CMakeLists.txt
index de1940ad..d91fc694 100644
--- a/logic/CMakeLists.txt
+++ b/logic/CMakeLists.txt
@@ -1,6 +1,6 @@
 project(MultiMC-Logic)
 
-SET(LOGIC_SOURCES
+set(LOGIC_SOURCES
 	# LOGIC - Base classes and infrastructure
 	BaseInstaller.h
 	BaseInstaller.cpp
@@ -14,11 +14,14 @@ SET(LOGIC_SOURCES
 	BaseInstance.h
 	BaseInstance.cpp
 	NullInstance.h
-	MMCError.h
 	MMCZip.h
 	MMCZip.cpp
 	MMCStrings.h
 	MMCStrings.cpp
+	BaseConfigObject.h
+	BaseConfigObject.cpp
+	AbstractCommonModel.h
+	AbstractCommonModel.cpp
 
 	# Prefix tree where node names are strings between separators
 	SeparatorPrefixTree.h
@@ -28,8 +31,11 @@ SET(LOGIC_SOURCES
 	Env.cpp
 
 	# JSON parsing helpers
-	MMCJson.h
-	MMCJson.cpp
+	Json.h
+	Json.cpp
+	FileSystem.h
+	FileSystem.cpp
+	Exception.h
 
 	# RW lock protected map
 	RWStorage.h
@@ -40,6 +46,20 @@ SET(LOGIC_SOURCES
 	# a smart pointer wrapper intended for safer use with Qt signal/slot mechanisms
 	QObjectPtr.h
 
+	# Resources
+	resources/IconResourceHandler.cpp
+	resources/IconResourceHandler.h
+	resources/Resource.cpp
+	resources/Resource.h
+	resources/ResourceHandler.cpp
+	resources/ResourceHandler.h
+	resources/ResourceObserver.cpp
+	resources/ResourceObserver.h
+	resources/WebResourceHandler.cpp
+	resources/WebResourceHandler.h
+	resources/ResourceProxyModel.h
+	resources/ResourceProxyModel.cpp
+
 	# network stuffs
 	net/NetAction.h
 	net/MD5EtagDownload.h
@@ -183,6 +203,8 @@ SET(LOGIC_SOURCES
 	tasks/ThreadTask.cpp
 	tasks/SequentialTask.h
 	tasks/SequentialTask.cpp
+	tasks/StandardTask.h
+	tasks/StandardTask.cpp
 
 	# Settings
 	settings/INIFile.cpp
diff --git a/logic/Env.cpp b/logic/Env.cpp
index 0607c7ea..2f26f211 100644
--- a/logic/Env.cpp
+++ b/logic/Env.cpp
@@ -148,6 +148,7 @@ void Env::initHttpMetaCache(QString rootPath, QString staticDataPath)
 	m_metacache->addBase("skins", QDir("accounts/skins").absolutePath());
 	m_metacache->addBase("root", QDir(rootPath).absolutePath());
 	m_metacache->addBase("translations", QDir(staticDataPath + "/translations").absolutePath());
+	m_metacache->addBase("icons", QDir("cache/icons").absolutePath());
 	m_metacache->Load();
 }
 
@@ -214,4 +215,4 @@ void Env::updateProxySettings(QString proxyTypeStr, QString addr, int port, QStr
 	qDebug() << proxyDesc;
 }
 
-#include "Env.moc"
\ No newline at end of file
+#include "Env.moc"
diff --git a/logic/Exception.h b/logic/Exception.h
new file mode 100644
index 00000000..2664910e
--- /dev/null
+++ b/logic/Exception.h
@@ -0,0 +1,41 @@
+// Licensed under the Apache-2.0 license. See README.md for details.
+
+#pragma once
+
+#include <QString>
+#include <QLoggingCategory>
+#include <exception>
+
+class Exception : public std::exception
+{
+public:
+	Exception(const QString &message) : std::exception(), m_message(message)
+	{
+		qCritical() << "Exception:" << message;
+	}
+	Exception(const Exception &other)
+		: std::exception(), m_message(other.cause())
+	{
+	}
+	virtual ~Exception() noexcept {}
+	const char *what() const noexcept
+	{
+		return m_message.toLatin1().constData();
+	}
+	QString cause() const
+	{
+		return m_message;
+	}
+
+private:
+	QString m_message;
+};
+
+#define DECLARE_EXCEPTION(name)                                                                \
+	class name##Exception : public ::Exception                                                 \
+	{                                                                                          \
+	public:                                                                                    \
+		name##Exception(const QString &message) : Exception(message)                           \
+		{                                                                                      \
+		}                                                                                      \
+	}
diff --git a/logic/FileSystem.cpp b/logic/FileSystem.cpp
new file mode 100644
index 00000000..b8d82c51
--- /dev/null
+++ b/logic/FileSystem.cpp
@@ -0,0 +1,56 @@
+// Licensed under the Apache-2.0 license. See README.md for details.
+
+#include "FileSystem.h"
+
+#include <QDir>
+#include <QSaveFile>
+#include <QFileInfo>
+
+void ensureExists(const QDir &dir)
+{
+	if (!QDir().mkpath(dir.absolutePath()))
+	{
+		throw FS::FileSystemException("Unable to create directory " + dir.dirName() + " (" +
+									  dir.absolutePath() + ")");
+	}
+}
+
+void FS::write(const QString &filename, const QByteArray &data)
+{
+	ensureExists(QFileInfo(filename).dir());
+	QSaveFile file(filename);
+	if (!file.open(QSaveFile::WriteOnly))
+	{
+		throw FileSystemException("Couldn't open " + filename + " for writing: " +
+								  file.errorString());
+	}
+	if (data.size() != file.write(data))
+	{
+		throw FileSystemException("Error writing data to " + filename + ": " +
+								  file.errorString());
+	}
+	if (!file.commit())
+	{
+		throw FileSystemException("Error while committing data to " + filename + ": " +
+								  file.errorString());
+	}
+}
+
+QByteArray FS::read(const QString &filename)
+{
+	QFile file(filename);
+	if (!file.open(QFile::ReadOnly))
+	{
+		throw FileSystemException("Unable to open " + filename + " for reading: " +
+								  file.errorString());
+	}
+	const qint64 size = file.size();
+	QByteArray data(int(size), 0);
+	const qint64 ret = file.read(data.data(), size);
+	if (ret == -1 || ret != size)
+	{
+		throw FileSystemException("Error reading data from " + filename + ": " +
+								  file.errorString());
+	}
+	return data;
+}
diff --git a/logic/FileSystem.h b/logic/FileSystem.h
new file mode 100644
index 00000000..e70f3165
--- /dev/null
+++ b/logic/FileSystem.h
@@ -0,0 +1,13 @@
+// Licensed under the Apache-2.0 license. See README.md for details.
+
+#pragma once
+
+#include "Exception.h"
+
+namespace FS
+{
+DECLARE_EXCEPTION(FileSystem);
+
+void write(const QString &filename, const QByteArray &data);
+QByteArray read(const QString &filename);
+}
diff --git a/logic/Json.cpp b/logic/Json.cpp
new file mode 100644
index 00000000..46055909
--- /dev/null
+++ b/logic/Json.cpp
@@ -0,0 +1,278 @@
+// Licensed under the Apache-2.0 license. See README.md for details.
+
+#include "Json.h"
+
+#include <QFile>
+#include <QSaveFile>
+
+#include "FileSystem.h"
+#include <math.h>
+
+namespace Json
+{
+void write(const QJsonDocument &doc, const QString &filename)
+{
+	FS::write(filename, doc.toJson());
+}
+void write(const QJsonObject &object, const QString &filename)
+{
+	write(QJsonDocument(object), filename);
+}
+void write(const QJsonArray &array, const QString &filename)
+{
+	write(QJsonDocument(array), filename);
+}
+
+QByteArray toBinary(const QJsonObject &obj)
+{
+	return QJsonDocument(obj).toBinaryData();
+}
+QByteArray toBinary(const QJsonArray &array)
+{
+	return QJsonDocument(array).toBinaryData();
+}
+QByteArray toText(const QJsonObject &obj)
+{
+	return QJsonDocument(obj).toJson(QJsonDocument::Compact);
+}
+QByteArray toText(const QJsonArray &array)
+{
+	return QJsonDocument(array).toJson(QJsonDocument::Compact);
+}
+
+static bool isBinaryJson(const QByteArray &data)
+{
+	decltype(QJsonDocument::BinaryFormatTag) tag = QJsonDocument::BinaryFormatTag;
+	return memcmp(data.constData(), &tag, sizeof(QJsonDocument::BinaryFormatTag)) == 0;
+}
+QJsonDocument ensureDocument(const QByteArray &data, const QString &what)
+{
+	if (isBinaryJson(data))
+	{
+		QJsonDocument doc = QJsonDocument::fromBinaryData(data);
+		if (doc.isNull())
+		{
+			throw JsonException(what + ": Invalid JSON (binary JSON detected)");
+		}
+		return doc;
+	}
+	else
+	{
+		QJsonParseError error;
+		QJsonDocument doc = QJsonDocument::fromJson(data, &error);
+		if (error.error != QJsonParseError::NoError)
+		{
+			throw JsonException(what + ": Error parsing JSON: " + error.errorString());
+		}
+		return doc;
+	}
+}
+QJsonDocument ensureDocument(const QString &filename, const QString &what)
+{
+	return ensureDocument(FS::read(filename), what);
+}
+QJsonObject ensureObject(const QJsonDocument &doc, const QString &what)
+{
+	if (!doc.isObject())
+	{
+		throw JsonException(what + " is not an object");
+	}
+	return doc.object();
+}
+QJsonArray ensureArray(const QJsonDocument &doc, const QString &what)
+{
+	if (!doc.isArray())
+	{
+		throw JsonException(what + " is not an array");
+	}
+	return doc.array();
+}
+
+void writeString(QJsonObject &to, const QString &key, const QString &value)
+{
+	if (!value.isEmpty())
+	{
+		to.insert(key, value);
+	}
+}
+
+void writeStringList(QJsonObject &to, const QString &key, const QStringList &values)
+{
+	if (!values.isEmpty())
+	{
+		QJsonArray array;
+		for(auto value: values)
+		{
+			array.append(value);
+		}
+		to.insert(key, array);
+	}
+}
+
+template<>
+QJsonValue toJson<QUrl>(const QUrl &url)
+{
+	return QJsonValue(url.toString(QUrl::FullyEncoded));
+}
+template<>
+QJsonValue toJson<QByteArray>(const QByteArray &data)
+{
+	return QJsonValue(QString::fromLatin1(data.toHex()));
+}
+template<>
+QJsonValue toJson<QDateTime>(const QDateTime &datetime)
+{
+	return QJsonValue(datetime.toString(Qt::ISODate));
+}
+template<>
+QJsonValue toJson<QDir>(const QDir &dir)
+{
+	return QDir::current().relativeFilePath(dir.absolutePath());
+}
+template<>
+QJsonValue toJson<QUuid>(const QUuid &uuid)
+{
+	return uuid.toString();
+}
+template<>
+QJsonValue toJson<QVariant>(const QVariant &variant)
+{
+	return QJsonValue::fromVariant(variant);
+}
+
+
+template<> QByteArray ensureIsType<QByteArray>(const QJsonValue &value, const Requirement,
+								   const QString &what)
+{
+	const QString string = ensureIsType<QString>(value, Required, what);
+	// ensure that the string can be safely cast to Latin1
+	if (string != QString::fromLatin1(string.toLatin1()))
+	{
+		throw JsonException(what + " is not encodable as Latin1");
+	}
+	return QByteArray::fromHex(string.toLatin1());
+}
+
+template<> QJsonArray ensureIsType<QJsonArray>(const QJsonValue &value, const Requirement, const QString &what)
+{
+	if (!value.isArray())
+	{
+		throw JsonException(what + " is not an array");
+	}
+	return value.toArray();
+}
+
+
+template<> QString ensureIsType<QString>(const QJsonValue &value, const Requirement, const QString &what)
+{
+	if (!value.isString())
+	{
+		throw JsonException(what + " is not a string");
+	}
+	return value.toString();
+}
+
+template<> bool ensureIsType<bool>(const QJsonValue &value, const Requirement,
+			 const QString &what)
+{
+	if (!value.isBool())
+	{
+		throw JsonException(what + " is not a bool");
+	}
+	return value.toBool();
+}
+
+template<> double ensureIsType<double>(const QJsonValue &value, const Requirement,
+							   const QString &what)
+{
+	if (!value.isDouble())
+	{
+		throw JsonException(what + " is not a double");
+	}
+	return value.toDouble();
+}
+
+template<> int ensureIsType<int>(const QJsonValue &value, const Requirement,
+			 const QString &what)
+{
+	const double doubl = ensureIsType<double>(value, Required, what);
+	if (fmod(doubl, 1) != 0)
+	{
+		throw JsonException(what + " is not an integer");
+	}
+	return int(doubl);
+}
+
+template<> QDateTime ensureIsType<QDateTime>(const QJsonValue &value, const Requirement,
+			 const QString &what)
+{
+	const QString string = ensureIsType<QString>(value, Required, what);
+	const QDateTime datetime = QDateTime::fromString(string, Qt::ISODate);
+	if (!datetime.isValid())
+	{
+		throw JsonException(what + " is not a ISO formatted date/time value");
+	}
+	return datetime;
+}
+
+template<> QUrl ensureIsType<QUrl>(const QJsonValue &value, const Requirement,
+			 const QString &what)
+{
+	const QString string = ensureIsType<QString>(value, Required, what);
+	if (string.isEmpty())
+	{
+		return QUrl();
+	}
+	const QUrl url = QUrl(string, QUrl::StrictMode);
+	if (!url.isValid())
+	{
+		throw JsonException(what + " is not a correctly formatted URL");
+	}
+	return url;
+}
+
+template<> QDir ensureIsType<QDir>(const QJsonValue &value, const Requirement, const QString &what)
+{
+	const QString string = ensureIsType<QString>(value, Required, what);
+	return QDir::current().absoluteFilePath(string);
+}
+
+template<> QUuid ensureIsType<QUuid>(const QJsonValue &value, const Requirement, const QString &what)
+{
+	const QString string = ensureIsType<QString>(value, Required, what);
+	const QUuid uuid = QUuid(string);
+	if (uuid.toString() != string) // converts back => valid
+	{
+		throw JsonException(what + " is not a valid UUID");
+	}
+	return uuid;
+}
+
+template<> QJsonObject ensureIsType<QJsonObject>(const QJsonValue &value, const Requirement, const QString &what)
+{
+	if (!value.isObject())
+	{
+		throw JsonException(what + " is not an object");
+	}
+	return value.toObject();
+}
+
+template<> QVariant ensureIsType<QVariant>(const QJsonValue &value, const Requirement, const QString &what)
+{
+	if (value.isNull() || value.isUndefined())
+	{
+		throw JsonException(what + " is null or undefined");
+	}
+	return value.toVariant();
+}
+
+template<> QJsonValue ensureIsType<QJsonValue>(const QJsonValue &value, const Requirement, const QString &what)
+{
+	if (value.isNull() || value.isUndefined())
+	{
+		throw JsonException(what + " is null or undefined");
+	}
+	return value;
+}
+
+}
diff --git a/logic/Json.h b/logic/Json.h
new file mode 100644
index 00000000..d22aa606
--- /dev/null
+++ b/logic/Json.h
@@ -0,0 +1,239 @@
+// Licensed under the Apache-2.0 license. See README.md for details.
+
+#pragma once
+
+#include <QJsonDocument>
+#include <QJsonArray>
+#include <QJsonObject>
+#include <QDateTime>
+#include <QUrl>
+#include <QDir>
+#include <QUuid>
+#include <QVariant>
+#include <memory>
+
+#include "Exception.h"
+
+namespace Json
+{
+DECLARE_EXCEPTION(Json);
+
+enum Requirement
+{
+	Required
+};
+
+void write(const QJsonDocument &doc, const QString &filename);
+void write(const QJsonObject &object, const QString &filename);
+void write(const QJsonArray &array, const QString &filename);
+QByteArray toBinary(const QJsonObject &obj);
+QByteArray toBinary(const QJsonArray &array);
+QByteArray toText(const QJsonObject &obj);
+QByteArray toText(const QJsonArray &array);
+
+QJsonDocument ensureDocument(const QByteArray &data, const QString &what = "Document");
+QJsonDocument ensureDocument(const QString &filename, const QString &what = "Document");
+QJsonObject ensureObject(const QJsonDocument &doc, const QString &what = "Document");
+QJsonArray ensureArray(const QJsonDocument &doc, const QString &what = "Document");
+
+/////////////////// WRITING ////////////////////
+
+void writeString(QJsonObject & to, const QString &key, const QString &value);
+void writeStringList(QJsonObject & to, const QString &key, const QStringList &values);
+
+template <typename T>
+void writeObjectList(QJsonObject & to, QString key, QList<std::shared_ptr<T>> values)
+{
+	if (!values.isEmpty())
+	{
+		QJsonArray array;
+		for (auto value: values)
+		{
+			array.append(value->toJson());
+		}
+		to.insert(key, array);
+	}
+}
+template <typename T>
+void writeObjectList(QJsonObject & to, QString key, QList<T> values)
+{
+	if (!values.isEmpty())
+	{
+		QJsonArray array;
+		for (auto value: values)
+		{
+			array.append(value.toJson());
+		}
+		to.insert(key, array);
+	}
+}
+
+template<typename T>
+QJsonValue toJson(const T &t)
+{
+	return QJsonValue(t);
+}
+template<>
+QJsonValue toJson<QUrl>(const QUrl &url);
+template<>
+QJsonValue toJson<QByteArray>(const QByteArray &data);
+template<>
+QJsonValue toJson<QDateTime>(const QDateTime &datetime);
+template<>
+QJsonValue toJson<QDir>(const QDir &dir);
+template<>
+QJsonValue toJson<QUuid>(const QUuid &uuid);
+template<>
+QJsonValue toJson<QVariant>(const QVariant &variant);
+
+template<typename T>
+QJsonArray toJsonArray(const QList<T> &container)
+{
+	QJsonArray array;
+	for (const T item : container)
+	{
+		array.append(toJson<T>(item));
+	}
+	return array;
+}
+
+////////////////// READING ////////////////////
+
+template <typename T>
+T ensureIsType(const QJsonValue &value, const Requirement requirement = Required, const QString &what = "Value");
+
+template<> double ensureIsType<double>(const QJsonValue &value, const Requirement, const QString &what);
+template<> bool ensureIsType<bool>(const QJsonValue &value, const Requirement, const QString &what);
+template<> int ensureIsType<int>(const QJsonValue &value, const Requirement, const QString &what);
+template<> QJsonObject ensureIsType<QJsonObject>(const QJsonValue &value, const Requirement, const QString &what);
+template<> QJsonArray ensureIsType<QJsonArray>(const QJsonValue &value, const Requirement, const QString &what);
+template<> QJsonValue ensureIsType<QJsonValue>(const QJsonValue &value, const Requirement, const QString &what);
+template<> QByteArray ensureIsType<QByteArray>(const QJsonValue &value, const Requirement, const QString &what);
+template<> QDateTime ensureIsType<QDateTime>(const QJsonValue &value, const Requirement, const QString &what);
+template<> QVariant ensureIsType<QVariant>(const QJsonValue &value, const Requirement, const QString &what);
+template<> QString ensureIsType<QString>(const QJsonValue &value, const Requirement, const QString &what);
+template<> QUuid ensureIsType<QUuid>(const QJsonValue &value, const Requirement, const QString &what);
+template<> QDir ensureIsType<QDir>(const QJsonValue &value, const Requirement, const QString &what);
+template<> QUrl ensureIsType<QUrl>(const QJsonValue &value, const Requirement, const QString &what);
+
+// the following functions are higher level functions, that make use of the above functions for
+// type conversion
+template <typename T>
+T ensureIsType(const QJsonValue &value, const T default_, const QString &what = "Value")
+{
+	if (value.isUndefined())
+	{
+		return default_;
+	}
+	return ensureIsType<T>(value, Required, what);
+}
+template <typename T>
+T ensureIsType(const QJsonObject &parent, const QString &key,
+			   const Requirement requirement = Required,
+			   const QString &what = "__placeholder__")
+{
+	const QString localWhat = QString(what).replace("__placeholder__", '\'' + key + '\'');
+	if (!parent.contains(key))
+	{
+		throw JsonException(localWhat + "s parent does not contain " + localWhat);
+	}
+	return ensureIsType<T>(parent.value(key), requirement, localWhat);
+}
+template <typename T>
+T ensureIsType(const QJsonObject &parent, const QString &key, const T default_,
+			   const QString &what = "__placeholder__")
+{
+	const QString localWhat = QString(what).replace("__placeholder__", '\'' + key + '\'');
+	if (!parent.contains(key))
+	{
+		return default_;
+	}
+	return ensureIsType<T>(parent.value(key), default_, localWhat);
+}
+
+template <typename T>
+QList<T> ensureIsArrayOf(const QJsonDocument &doc)
+{
+	const QJsonArray array = ensureArray(doc);
+	QList<T> out;
+	for (const QJsonValue val : array)
+	{
+		out.append(ensureIsType<T>(val, Required, "Document"));
+	}
+	return out;
+}
+template <typename T>
+QList<T> ensureIsArrayOf(const QJsonValue &value, const Requirement = Required,
+						 const QString &what = "Value")
+{
+	const QJsonArray array = ensureIsType<QJsonArray>(value, Required, what);
+	QList<T> out;
+	for (const QJsonValue val : array)
+	{
+		out.append(ensureIsType<T>(val, Required, what));
+	}
+	return out;
+}
+template <typename T>
+QList<T> ensureIsArrayOf(const QJsonValue &value, const QList<T> default_,
+						 const QString &what = "Value")
+{
+	if (value.isUndefined())
+	{
+		return default_;
+	}
+	return ensureIsArrayOf<T>(value, Required, what);
+}
+template <typename T>
+QList<T> ensureIsArrayOf(const QJsonObject &parent, const QString &key,
+						 const Requirement requirement = Required,
+						 const QString &what = "__placeholder__")
+{
+	const QString localWhat = QString(what).replace("__placeholder__", '\'' + key + '\'');
+	if (!parent.contains(key))
+	{
+		throw JsonException(localWhat + "s parent does not contain " + localWhat);
+	}
+	return ensureIsArrayOf<T>(parent.value(key), requirement, localWhat);
+}
+template <typename T>
+QList<T> ensureIsArrayOf(const QJsonObject &parent, const QString &key,
+						 const QList<T> &default_, const QString &what = "__placeholder__")
+{
+	const QString localWhat = QString(what).replace("__placeholder__", '\'' + key + '\'');
+	if (!parent.contains(key))
+	{
+		return default_;
+	}
+	return ensureIsArrayOf<T>(parent.value(key), default_, localWhat);
+}
+
+// this macro part could be replaced by variadic functions that just pass on their arguments, but that wouldn't work well with IDE helpers
+#define JSON_HELPERFUNCTIONS(NAME, TYPE) \
+	inline TYPE ensure##NAME(const QJsonValue &value, const Requirement requirement = Required, const QString &what = "Value") \
+{ return ensureIsType<TYPE>(value, requirement, what); } \
+	inline TYPE ensure##NAME(const QJsonValue &value, const TYPE default_, const QString &what = "Value") \
+{ return ensureIsType<TYPE>(value, default_, what); } \
+	inline TYPE ensure##NAME(const QJsonObject &parent, const QString &key, const Requirement requirement = Required, const QString &what = "__placeholder__") \
+{ return ensureIsType<TYPE>(parent, key, requirement, what); } \
+	inline TYPE ensure##NAME(const QJsonObject &parent, const QString &key, const TYPE default_, const QString &what = "__placeholder") \
+{ return ensureIsType<TYPE>(parent, key, default_, what); }
+
+JSON_HELPERFUNCTIONS(Array, QJsonArray)
+JSON_HELPERFUNCTIONS(Object, QJsonObject)
+JSON_HELPERFUNCTIONS(JsonValue, QJsonValue)
+JSON_HELPERFUNCTIONS(String, QString)
+JSON_HELPERFUNCTIONS(Boolean, bool)
+JSON_HELPERFUNCTIONS(Double, double)
+JSON_HELPERFUNCTIONS(Integer, int)
+JSON_HELPERFUNCTIONS(DateTime, QDateTime)
+JSON_HELPERFUNCTIONS(Url, QUrl)
+JSON_HELPERFUNCTIONS(ByteArray, QByteArray)
+JSON_HELPERFUNCTIONS(Dir, QDir)
+JSON_HELPERFUNCTIONS(Uuid, QUuid)
+JSON_HELPERFUNCTIONS(Variant, QVariant)
+
+#undef JSON_HELPERFUNCTIONS
+
+}
+using JSONValidationError = Json::JsonException;
diff --git a/logic/MMCError.h b/logic/MMCError.h
deleted file mode 100644
index e81054a6..00000000
--- a/logic/MMCError.h
+++ /dev/null
@@ -1,25 +0,0 @@
-#pragma once
-#include <exception>
-#include <QString>
-#include <QDebug>
-
-class MMCError : public std::exception
-{
-public:
-	MMCError(QString cause)
-	{
-		exceptionCause = cause;
-		qCritical() << "Exception: " + cause;
-	};
-	virtual ~MMCError() noexcept {}
-	virtual const char *what() const noexcept
-	{
-		return exceptionCause.toLocal8Bit();
-	};
-	virtual QString cause() const
-	{
-		return exceptionCause;
-	}
-private:
-	QString exceptionCause;
-};
diff --git a/logic/MMCJson.cpp b/logic/MMCJson.cpp
deleted file mode 100644
index 23af4fff..00000000
--- a/logic/MMCJson.cpp
+++ /dev/null
@@ -1,142 +0,0 @@
-#include "MMCJson.h"
-
-#include <QString>
-#include <QUrl>
-#include <QStringList>
-#include <math.h>
-
-QJsonDocument MMCJson::parseDocument(const QByteArray &data, const QString &what)
-{
-	QJsonParseError error;
-	QJsonDocument doc = QJsonDocument::fromJson(data, &error);
-	if (error.error != QJsonParseError::NoError)
-	{
-		throw JSONValidationError(what + " is not valid JSON: " + error.errorString() + " at " + error.offset);
-	}
-	return doc;
-}
-
-bool MMCJson::ensureBoolean(const QJsonValue val, const QString what)
-{
-	if (!val.isBool())
-		throw JSONValidationError(what + " is not boolean");
-	return val.toBool();
-}
-
-QJsonValue MMCJson::ensureExists(QJsonValue val, const QString what)
-{
-	if(val.isUndefined() || val.isUndefined())
-		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();
-}
-
-QJsonArray MMCJson::ensureArray(const QJsonDocument &val, const QString &what)
-{
-	if (!val.isArray())
-	{
-		throw JSONValidationError(what + " is not an array");
-	}
-	return val.array();
-}
-
-double MMCJson::ensureDouble(const QJsonValue val, const QString what)
-{
-	if (!val.isDouble())
-		throw JSONValidationError(what + " is not a number");
-	return 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();
-}
-
-QUrl MMCJson::ensureUrl(const QJsonValue &val, const QString &what)
-{
-	const QUrl url = QUrl(ensureString(val, what));
-	if (!url.isValid())
-	{
-		throw JSONValidationError(what + " is not an url");
-	}
-	return url;
-}
-
-QJsonDocument MMCJson::parseFile(const QString &filename, const QString &what)
-{
-	QFile f(filename);
-	if (!f.open(QFile::ReadOnly))
-	{
-		throw FileOpenError(f);
-	}
-	return parseDocument(f.readAll(), what);
-}
-
-int MMCJson::ensureInteger(const QJsonValue val, QString what, const int def)
-{
-	if (val.isUndefined())
-		return def;
-	return ensureInteger(val, what);
-}
-
-void MMCJson::writeString(QJsonObject &to, QString key, QString value)
-{
-	if (!value.isEmpty())
-	{
-		to.insert(key, value);
-	}
-}
-
-void MMCJson::writeStringList(QJsonObject &to, QString key, QStringList values)
-{
-	if (!values.isEmpty())
-	{
-		QJsonArray array;
-		for(auto value: values)
-		{
-			array.append(value);
-		}
-		to.insert(key, array);
-	}
-}
-
-QStringList MMCJson::ensureStringList(const QJsonValue val, QString what)
-{
-	const QJsonArray array = ensureArray(val, what);
-	QStringList out;
-	for (const auto value : array)
-	{
-		out.append(ensureString(value));
-	}
-	return out;
-}
diff --git a/logic/MMCJson.h b/logic/MMCJson.h
deleted file mode 100644
index dc0b4224..00000000
--- a/logic/MMCJson.h
+++ /dev/null
@@ -1,101 +0,0 @@
-/**
- * Some de-bullshitting for Qt JSON failures.
- *
- * Simple exception-throwing
- */
-
-#pragma once
-#include <QJsonValue>
-#include <QJsonObject>
-#include <QJsonDocument>
-#include <QJsonArray>
-#include <QFile>
-#include <memory>
-#include "MMCError.h"
-
-class JSONValidationError : public MMCError
-{
-public:
-	JSONValidationError(QString cause) : MMCError(cause) {}
-};
-class FileOpenError : public MMCError
-{
-public:
-	FileOpenError(const QFile &file) : MMCError(QObject::tr("Error opening %1: %2").arg(file.fileName(), file.errorString())) {}
-};
-
-namespace MMCJson
-{
-/// parses the data into a json document. throws if there's a parse error
-QJsonDocument parseDocument(const QByteArray &data, const QString &what);
-
-/// tries to open and then parses the specified file. throws if there's an error
-QJsonDocument parseFile(const QString &filename, const QString &what);
-
-/// 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 = "document");
-
-/// make sure the value is converted into an array. throw otherwise.
-QJsonArray ensureArray(const QJsonValue val, QString what = "value");
-
-/// make sure the document is converted into an array. throw otherwise.
-QJsonArray ensureArray(const QJsonDocument &val, const QString &what = "document");
-
-/// 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 string that's parseable as an url. throw otherwise.
-QUrl ensureUrl(const QJsonValue &val, const 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 an integer. throw otherwise. this version will return the default value if the field is undefined.
-int ensureInteger(const QJsonValue val, QString what, const int def);
-
-/// make sure the value is converted into a double precision floating number. throw otherwise.
-double ensureDouble(const QJsonValue val, QString what = "value");
-
-QStringList ensureStringList(const QJsonValue val, QString what);
-
-void writeString(QJsonObject & to, QString key, QString value);
-
-void writeStringList(QJsonObject & to, QString key, QStringList values);
-
-template <typename T>
-void writeObjectList(QJsonObject & to, QString key, QList<std::shared_ptr<T>> values)
-{
-	if (!values.isEmpty())
-	{
-		QJsonArray array;
-		for (auto value: values)
-		{
-			array.append(value->toJson());
-		}
-		to.insert(key, array);
-	}
-}
-template <typename T>
-void writeObjectList(QJsonObject & to, QString key, QList<T> values)
-{
-	if (!values.isEmpty())
-	{
-		QJsonArray array;
-		for (auto value: values)
-		{
-			array.append(value.toJson());
-		}
-		to.insert(key, array);
-	}
-}
-}
-
diff --git a/logic/QObjectPtr.h b/logic/QObjectPtr.h
index 2bde1bd8..32e59bd9 100644
--- a/logic/QObjectPtr.h
+++ b/logic/QObjectPtr.h
@@ -19,6 +19,11 @@ public:
 	{
 		m_ptr = other.m_ptr;
 	}
+	template<typename Derived>
+	QObjectPtr(const QObjectPtr<Derived> &other)
+	{
+		m_ptr = other.unwrap();
+	}
 
 public:
 	void reset(T * wrap)
diff --git a/logic/forge/ForgeInstaller.cpp b/logic/forge/ForgeInstaller.cpp
index 18527c49..32ce5788 100644
--- a/logic/forge/ForgeInstaller.cpp
+++ b/logic/forge/ForgeInstaller.cpp
@@ -22,6 +22,7 @@
 #include "forge/ForgeVersionList.h"
 #include "minecraft/VersionFilterData.h"
 #include "Env.h"
+#include "Exception.h"
 
 #include <quazip.h>
 #include <quazipfile.h>
@@ -412,7 +413,7 @@ protected:
 			m_instance->reloadProfile();
 			emitSucceeded();
 		}
-		catch (MMCError &e)
+		catch (Exception &e)
 		{
 			emitFailed(e.cause());
 		}
diff --git a/logic/liteloader/LiteLoaderInstaller.cpp b/logic/liteloader/LiteLoaderInstaller.cpp
index 9a06d620..e255921f 100644
--- a/logic/liteloader/LiteLoaderInstaller.cpp
+++ b/logic/liteloader/LiteLoaderInstaller.cpp
@@ -24,6 +24,7 @@
 #include "minecraft/OneSixLibrary.h"
 #include "minecraft/OneSixInstance.h"
 #include "liteloader/LiteLoaderVersionList.h"
+#include "Exception.h"
 
 LiteLoaderInstaller::LiteLoaderInstaller() : BaseInstaller()
 {
@@ -118,7 +119,7 @@ protected:
 				m_instance->reloadProfile();
 				emitSucceeded();
 			}
-			catch (MMCError &e)
+			catch (Exception &e)
 			{
 				emitFailed(e.cause());
 			}
diff --git a/logic/liteloader/LiteLoaderVersionList.cpp b/logic/liteloader/LiteLoaderVersionList.cpp
index 8b3c13e0..21bb4f50 100644
--- a/logic/liteloader/LiteLoaderVersionList.cpp
+++ b/logic/liteloader/LiteLoaderVersionList.cpp
@@ -16,7 +16,7 @@
 #include "LiteLoaderVersionList.h"
 #include "Env.h"
 #include "net/URLConstants.h"
-#include "MMCError.h"
+#include "Exception.h"
 
 #include <QtXml>
 
@@ -254,7 +254,7 @@ void LLListLoadTask::listDownloaded()
 					}
 					version->libraries.append(lib);
 				}
-				catch (MMCError &e)
+				catch (Exception &e)
 				{
 					qCritical() << "Couldn't read JSON object:";
 					continue;
diff --git a/logic/minecraft/JarMod.cpp b/logic/minecraft/JarMod.cpp
index bf711c1f..bf985707 100644
--- a/logic/minecraft/JarMod.cpp
+++ b/logic/minecraft/JarMod.cpp
@@ -1,6 +1,6 @@
 #include "JarMod.h"
-#include "MMCJson.h"
-using namespace MMCJson;
+#include "Json.h"
+using namespace Json;
 
 JarmodPtr Jarmod::fromJson(const QJsonObject &libObj, const QString &filename, const QString &originalName)
 {
diff --git a/logic/minecraft/MinecraftProfile.cpp b/logic/minecraft/MinecraftProfile.cpp
index 0661aec1..1baf008e 100644
--- a/logic/minecraft/MinecraftProfile.cpp
+++ b/logic/minecraft/MinecraftProfile.cpp
@@ -17,12 +17,13 @@
 #include <QDir>
 #include <QJsonDocument>
 #include <QJsonArray>
+#include <QDebug>
 #include <pathutils.h>
 
 #include "minecraft/MinecraftProfile.h"
 #include "ProfileUtils.h"
 #include "NullProfileStrategy.h"
-#include "VersionBuildError.h"
+#include "Exception.h"
 
 MinecraftProfile::MinecraftProfile(ProfileStrategy *strategy)
 	: QAbstractListModel()
@@ -277,7 +278,7 @@ std::shared_ptr<MinecraftProfile> MinecraftProfile::fromJson(const QJsonObject &
 		file->applyTo(version.get());
 		version->appendPatch(file);
 	}
-	catch(MMCError & err)
+	catch(Exception &err)
 	{
 		return 0;
 	}
@@ -424,7 +425,7 @@ bool MinecraftProfile::reapplySafe()
 	{
 		reapply();
 	}
-	catch(MMCError & error)
+	catch (Exception & error)
 	{
 		clear();
 		qWarning() << "Couldn't apply profile patches because: " << error.cause();
diff --git a/logic/minecraft/MinecraftVersionList.cpp b/logic/minecraft/MinecraftVersionList.cpp
index c20534e9..44be281b 100644
--- a/logic/minecraft/MinecraftVersionList.cpp
+++ b/logic/minecraft/MinecraftVersionList.cpp
@@ -14,12 +14,12 @@
  */
 
 #include <QtXml>
-#include "MMCJson.h"
+#include "Json.h"
 #include <QtAlgorithms>
 #include <QtNetwork>
 
 #include "Env.h"
-#include "MMCError.h"
+#include "Exception.h"
 
 #include "MinecraftVersionList.h"
 #include "net/URLConstants.h"
@@ -71,10 +71,10 @@ protected:
 	MinecraftVersionList *m_list;
 };
 
-class ListLoadError : public MMCError
+class ListLoadError : public Exception
 {
 public:
-	ListLoadError(QString cause) : MMCError(cause) {};
+	ListLoadError(QString cause) : Exception(cause) {};
 	virtual ~ListLoadError() noexcept
 	{
 	}
@@ -142,7 +142,7 @@ void MinecraftVersionList::loadCachedList()
 		}
 		loadMojangList(jsonDoc, Local);
 	}
-	catch (MMCError &e)
+	catch (Exception &e)
 	{
 		// the cache has gone bad for some reason... flush it.
 		qCritical() << "The minecraft version cache is corrupted. Flushing cache.";
@@ -157,12 +157,11 @@ void MinecraftVersionList::loadBuiltinList()
 	qDebug() << "Loading builtin version list.";
 	// grab the version list data from internal resources.
 	const QJsonDocument doc =
-		MMCJson::parseFile(":/versions/minecraft.json",
-						   "builtin version list");
+		Json::ensureDocument(QString(":/versions/minecraft.json"), "builtin version list");
 	const QJsonObject root = doc.object();
 
 	// parse all the versions
-	for (const auto version : MMCJson::ensureArray(root.value("versions")))
+	for (const auto version : Json::ensureArray(root.value("versions")))
 	{
 		QJsonObject versionObj = version.toObject();
 		QString versionID = versionObj.value("id").toString("");
@@ -204,9 +203,9 @@ void MinecraftVersionList::loadBuiltinList()
 		mcVersion->m_processArguments = versionObj.value("processArguments").toString("legacy");
 		if (versionObj.contains("+traits"))
 		{
-			for (auto traitVal : MMCJson::ensureArray(versionObj.value("+traits")))
+			for (auto traitVal : Json::ensureArray(versionObj.value("+traits")))
 			{
-				mcVersion->m_traits.insert(MMCJson::ensureString(traitVal));
+				mcVersion->m_traits.insert(Json::ensureString(traitVal));
 			}
 		}
 		m_lookup[versionID] = mcVersion;
@@ -227,11 +226,11 @@ void MinecraftVersionList::loadMojangList(QJsonDocument jsonDoc, VersionSource s
 
 	try
 	{
-		QJsonObject latest = MMCJson::ensureObject(root.value("latest"));
-		m_latestReleaseID = MMCJson::ensureString(latest.value("release"));
-		m_latestSnapshotID = MMCJson::ensureString(latest.value("snapshot"));
+		QJsonObject latest = Json::ensureObject(root.value("latest"));
+		m_latestReleaseID = Json::ensureString(latest.value("release"));
+		m_latestSnapshotID = Json::ensureString(latest.value("snapshot"));
 	}
-	catch (MMCError &err)
+	catch (Exception &err)
 	{
 		qCritical()
 			<< tr("Error parsing version list JSON: couldn't determine latest versions");
@@ -481,7 +480,7 @@ void MCVListLoadTask::list_downloaded()
 		}
 		m_list->loadMojangList(jsonDoc, Remote);
 	}
-	catch (MMCError &e)
+	catch (Exception &e)
 	{
 		emitFailed(e.cause());
 		return;
@@ -532,7 +531,7 @@ void MCVListVersionUpdateTask::json_downloaded()
 	{
 		file = VersionFile::fromJson(jsonDoc, "net.minecraft.json", false);
 	}
-	catch (MMCError &e)
+	catch (Exception &e)
 	{
 		emitFailed(tr("Couldn't process version file: %1").arg(e.cause()));
 		return;
diff --git a/logic/minecraft/OneSixInstance.cpp b/logic/minecraft/OneSixInstance.cpp
index ffccc259..b7937e31 100644
--- a/logic/minecraft/OneSixInstance.cpp
+++ b/logic/minecraft/OneSixInstance.cpp
@@ -16,7 +16,6 @@
 #include <QIcon>
 #include <pathutils.h>
 #include <QDebug>
-#include "MMCError.h"
 
 #include "minecraft/OneSixInstance.h"
 
@@ -338,7 +337,7 @@ void OneSixInstance::reloadProfile()
 	catch (VersionIncomplete &error)
 	{
 	}
-	catch (MMCError &error)
+	catch (Exception &error)
 	{
 		m_version->clear();
 		setFlag(VersionBrokenFlag);
diff --git a/logic/minecraft/OneSixProfileStrategy.cpp b/logic/minecraft/OneSixProfileStrategy.cpp
index 173cd4d6..f5de690b 100644
--- a/logic/minecraft/OneSixProfileStrategy.cpp
+++ b/logic/minecraft/OneSixProfileStrategy.cpp
@@ -294,7 +294,7 @@ bool OneSixProfileStrategy::customizePatch(ProfilePatchPtr patch)
 	{
 		qDebug() << "Version was incomplete:" << error.cause();
 	}
-	catch (MMCError &error)
+	catch (Exception &error)
 	{
 		qWarning() << "Version could not be loaded:" << error.cause();
 	}
@@ -324,7 +324,7 @@ bool OneSixProfileStrategy::revertPatch(ProfilePatchPtr patch)
 	{
 		qDebug() << "Version was incomplete:" << error.cause();
 	}
-	catch (MMCError &error)
+	catch (Exception &error)
 	{
 		qWarning() << "Version could not be loaded:" << error.cause();
 	}
diff --git a/logic/minecraft/OneSixUpdate.cpp b/logic/minecraft/OneSixUpdate.cpp
index 485727ec..8463ead6 100644
--- a/logic/minecraft/OneSixUpdate.cpp
+++ b/logic/minecraft/OneSixUpdate.cpp
@@ -33,6 +33,7 @@
 #include "forge/ForgeMirrors.h"
 #include "net/URLConstants.h"
 #include "minecraft/AssetsUtils.h"
+#include "Exception.h"
 #include "MMCZip.h"
 
 OneSixUpdate::OneSixUpdate(OneSixInstance *inst, QObject *parent) : Task(parent), m_inst(inst)
@@ -182,7 +183,7 @@ void OneSixUpdate::jarlibStart()
 	{
 		inst->reloadProfile();
 	}
-	catch (MMCError &e)
+	catch (Exception &e)
 	{
 		emitFailed(e.cause());
 		return;
diff --git a/logic/minecraft/ParseUtils.cpp b/logic/minecraft/ParseUtils.cpp
index 49e0e0ca..8fccf403 100644
--- a/logic/minecraft/ParseUtils.cpp
+++ b/logic/minecraft/ParseUtils.cpp
@@ -1,7 +1,6 @@
 #include <QDateTime>
 #include <QString>
 #include "ParseUtils.h"
-#include <MMCJson.h>
 
 QDateTime timeFromS3Time(QString str)
 {
diff --git a/logic/minecraft/ProfileUtils.cpp b/logic/minecraft/ProfileUtils.cpp
index 3eaca920..68fe0f14 100644
--- a/logic/minecraft/ProfileUtils.cpp
+++ b/logic/minecraft/ProfileUtils.cpp
@@ -1,6 +1,6 @@
 #include "ProfileUtils.h"
 #include "minecraft/VersionFilterData.h"
-#include "MMCJson.h"
+#include "Json.h"
 #include <QDebug>
 
 #include <QJsonDocument>
@@ -74,18 +74,18 @@ bool readOverrideOrders(QString path, PatchOrder &order)
 	// and then read it and process it if all above is true.
 	try
 	{
-		auto obj = MMCJson::ensureObject(doc);
+		auto obj = Json::ensureObject(doc);
 		// check order file version.
-		auto version = MMCJson::ensureInteger(obj.value("version"), "version");
+		auto version = Json::ensureInteger(obj.value("version"));
 		if (version != currentOrderFileVersion)
 		{
 			throw JSONValidationError(QObject::tr("Invalid order file version, expected %1")
 										  .arg(currentOrderFileVersion));
 		}
-		auto orderArray = MMCJson::ensureArray(obj.value("order"));
+		auto orderArray = Json::ensureArray(obj.value("order"));
 		for(auto item: orderArray)
 		{
-			order.append(MMCJson::ensureString(item));
+			order.append(Json::ensureString(item));
 		}
 	}
 	catch (JSONValidationError &err)
diff --git a/logic/minecraft/RawLibrary.cpp b/logic/minecraft/RawLibrary.cpp
index c4cd97a1..90883312 100644
--- a/logic/minecraft/RawLibrary.cpp
+++ b/logic/minecraft/RawLibrary.cpp
@@ -1,5 +1,5 @@
-#include "MMCJson.h"
-using namespace MMCJson;
+#include "Json.h"
+using namespace Json;
 
 #include "RawLibrary.h"
 #include <pathutils.h>
@@ -74,7 +74,7 @@ RawLibraryPtr RawLibrary::fromJsonPlus(const QJsonObject &libObj, const QString
 	auto lib = RawLibrary::fromJson(libObj, filename);
 	if (libObj.contains("insert"))
 	{
-		QJsonValue insertVal = ensureExists(libObj.value("insert"), "library insert rule");
+		QJsonValue insertVal = ensureJsonValue(libObj.value("insert"), "library insert rule");
 		if (insertVal.isString())
 		{
 			// it's just a simple string rule. OK.
diff --git a/logic/minecraft/VersionBuildError.h b/logic/minecraft/VersionBuildError.h
index ae479851..fda453e5 100644
--- a/logic/minecraft/VersionBuildError.h
+++ b/logic/minecraft/VersionBuildError.h
@@ -1,9 +1,9 @@
-#include "MMCError.h"
+#include "Exception.h"
 
-class VersionBuildError : public MMCError
+class VersionBuildError : public Exception
 {
 public:
-	VersionBuildError(QString cause) : MMCError(cause) {};
+	explicit VersionBuildError(QString cause) : Exception(cause) {}
 	virtual ~VersionBuildError() noexcept
 	{
 	}
@@ -55,4 +55,4 @@ public:
 	virtual ~VersionIncomplete() noexcept
 	{
 	}
-};
\ No newline at end of file
+};
diff --git a/logic/minecraft/VersionFile.cpp b/logic/minecraft/VersionFile.cpp
index 227ba8be..426cba8c 100644
--- a/logic/minecraft/VersionFile.cpp
+++ b/logic/minecraft/VersionFile.cpp
@@ -10,8 +10,8 @@
 #include "minecraft/JarMod.h"
 #include "ParseUtils.h"
 
-#include "MMCJson.h"
-using namespace MMCJson;
+#include "Json.h"
+using namespace Json;
 
 #include "VersionBuildError.h"
 
diff --git a/logic/minecraft/VersionFile.h b/logic/minecraft/VersionFile.h
index dd5c962f..e5ce4026 100644
--- a/logic/minecraft/VersionFile.h
+++ b/logic/minecraft/VersionFile.h
@@ -3,11 +3,12 @@
 #include <QString>
 #include <QStringList>
 #include <QDateTime>
+#include <QSet>
+
 #include <memory>
 #include "minecraft/OpSys.h"
 #include "minecraft/OneSixRule.h"
 #include "ProfilePatch.h"
-#include "MMCError.h"
 #include "OneSixLibrary.h"
 #include "JarMod.h"
 
diff --git a/logic/net/CacheDownload.h b/logic/net/CacheDownload.h
index 49d2d99f..7f95a69d 100644
--- a/logic/net/CacheDownload.h
+++ b/logic/net/CacheDownload.h
@@ -20,6 +20,29 @@
 #include <QCryptographicHash>
 #include <QSaveFile>
 
+class INetworkValidator
+{
+public:
+	virtual ~INetworkValidator() {}
+
+	virtual void validate(const QByteArray &data) = 0;
+};
+class JsonValidator : public INetworkValidator
+{
+public:
+	void validate(const QByteArray &data) override;
+};
+class MD5HashValidator : public INetworkValidator
+{
+public:
+	explicit MD5HashValidator(const QByteArray &expected)
+		: m_expected(expected) {}
+	void validate(const QByteArray &data) override;
+
+private:
+	QByteArray m_expected;
+};
+
 typedef std::shared_ptr<class CacheDownload> CacheDownloadPtr;
 class CacheDownload : public NetAction
 {
@@ -33,6 +56,8 @@ private:
 	/// the hash-as-you-download
 	QCryptographicHash md5sum;
 
+	INetworkValidator *m_validator = nullptr;
+
 	bool wroteAnyData = false;
 
 public:
@@ -46,6 +71,10 @@ public:
 	{
 		return m_target_path;
 	}
+	void setValidator(INetworkValidator *validator)
+	{
+		m_validator = validator;
+	}
 protected
 slots:
 	virtual void downloadProgress(qint64 bytesReceived, qint64 bytesTotal);
diff --git a/logic/resources/IconResourceHandler.cpp b/logic/resources/IconResourceHandler.cpp
new file mode 100644
index 00000000..d47dcc3d
--- /dev/null
+++ b/logic/resources/IconResourceHandler.cpp
@@ -0,0 +1,60 @@
+#include "IconResourceHandler.h"
+
+#include <QDir>
+#include <QDebug>
+
+QString IconResourceHandler::m_theme = "multimc";
+QList<std::weak_ptr<IconResourceHandler>> IconResourceHandler::m_iconHandlers;
+
+IconResourceHandler::IconResourceHandler(const QString &key)
+	: m_key(key)
+{
+}
+
+void IconResourceHandler::setTheme(const QString &theme)
+{
+	m_theme = theme;
+
+	for (auto handler : m_iconHandlers)
+	{
+		std::shared_ptr<IconResourceHandler> ptr = handler.lock();
+		if (ptr)
+		{
+			ptr->setResult(ptr->get());
+		}
+	}
+}
+
+void IconResourceHandler::init(std::shared_ptr<ResourceHandler> &ptr)
+{
+	m_iconHandlers.append(std::dynamic_pointer_cast<IconResourceHandler>(ptr));
+	setResult(get());
+}
+
+QVariant IconResourceHandler::get() const
+{
+	const QDir iconsDir = QDir(":/icons/" + m_theme);
+
+	QVariantMap out;
+	for (const QFileInfo &sizeInfo : iconsDir.entryInfoList(QDir::Dirs | QDir::NoDotAndDotDot))
+	{
+		const QDir dir = QDir(sizeInfo.absoluteFilePath());
+		const QString dirName = sizeInfo.fileName();
+		const int size = dirName.left(dirName.indexOf('x')).toInt();
+		if (dir.exists(m_key + ".png") && dirName != "scalable")
+		{
+			out.insert(dir.absoluteFilePath(m_key + ".png"), size);
+		}
+		else if (dir.exists(m_key + ".svg") && dirName == "scalable")
+		{
+			out.insert(dir.absoluteFilePath(m_key + ".svg"), size);
+		}
+	}
+
+	if (out.isEmpty())
+	{
+		qWarning() << "Couldn't find any icons for" << m_key;
+	}
+
+	return out;
+}
diff --git a/logic/resources/IconResourceHandler.h b/logic/resources/IconResourceHandler.h
new file mode 100644
index 00000000..dedfecb2
--- /dev/null
+++ b/logic/resources/IconResourceHandler.h
@@ -0,0 +1,22 @@
+#pragma once
+
+#include <memory>
+
+#include "ResourceHandler.h"
+
+class IconResourceHandler : public ResourceHandler
+{
+public:
+	explicit IconResourceHandler(const QString &key);
+
+	static void setTheme(const QString &theme);
+
+private:
+	void init(std::shared_ptr<ResourceHandler> &ptr) override;
+
+	QString m_key;
+	static QString m_theme;
+	static QList<std::weak_ptr<IconResourceHandler>> m_iconHandlers;
+
+	QVariant get() const;
+};
diff --git a/logic/resources/Resource.cpp b/logic/resources/Resource.cpp
new file mode 100644
index 00000000..16ed3d2d
--- /dev/null
+++ b/logic/resources/Resource.cpp
@@ -0,0 +1,121 @@
+#include "Resource.h"
+
+#include <QDebug>
+
+#include "WebResourceHandler.h"
+#include "IconResourceHandler.h"
+#include "ResourceObserver.h"
+
+QMap<QString, std::function<std::shared_ptr<ResourceHandler>(const QString &)>> Resource::m_handlers;
+QMap<QPair<int, int>, std::function<QVariant(QVariant)>> Resource::m_transfomers;
+QMap<QString, std::weak_ptr<Resource>> Resource::m_resources;
+
+Resource::Resource(const QString &resource)
+{
+	if (!m_handlers.contains("web"))
+	{
+		registerHandler<WebResourceHandler>("web");
+	}
+	if (!m_handlers.contains("icon"))
+	{
+		registerHandler<IconResourceHandler>("icon");
+	}
+
+	Q_ASSERT(resource.contains(':'));
+	const QString resourceId = resource.left(resource.indexOf(':'));
+	Q_ASSERT(m_handlers.contains(resourceId));
+	m_handler = m_handlers.value(resourceId)(resource.mid(resource.indexOf(':') + 1));
+	m_handler->init(m_handler);
+	m_handler->setResource(this);
+	Q_ASSERT(m_handler);
+}
+Resource::~Resource()
+{
+	qDeleteAll(m_observers);
+}
+
+Resource::Ptr Resource::create(const QString &resource)
+{
+	Resource::Ptr ptr = m_resources.contains(resource)
+			? m_resources.value(resource).lock()
+			: nullptr;
+	if (!ptr)
+	{
+		struct ConstructableResource : public Resource
+		{
+			explicit ConstructableResource(const QString &resource)
+				: Resource(resource) {}
+		};
+		ptr = std::make_shared<ConstructableResource>(resource);
+		m_resources.insert(resource, ptr);
+	}
+	return ptr;
+}
+
+Resource::Ptr Resource::applyTo(ResourceObserver *observer)
+{
+	m_observers.append(observer);
+	observer->setSource(shared_from_this()); // give the observer a shared_ptr for us so we don't get deleted
+	observer->resourceUpdated();
+	return shared_from_this();
+}
+Resource::Ptr Resource::applyTo(QObject *target, const char *property)
+{
+	// the cast to ResourceObserver* is required to ensure the right overload gets choosen
+	return applyTo(static_cast<ResourceObserver *>(new QObjectResourceObserver(target, property)));
+}
+
+Resource::Ptr Resource::placeholder(Resource::Ptr other)
+{
+	m_placeholder = other;
+	for (ResourceObserver *observer : m_observers)
+	{
+		observer->resourceUpdated();
+	}
+	return shared_from_this();
+}
+
+QVariant Resource::getResourceInternal(const int typeId) const
+{
+	if (m_handler->result().isNull() && m_placeholder)
+	{
+		return m_placeholder->getResourceInternal(typeId);
+	}
+	const QVariant variant = m_handler->result();
+	const auto typePair = qMakePair(int(variant.type()), typeId);
+	if (m_transfomers.contains(typePair))
+	{
+		return m_transfomers.value(typePair)(variant);
+	}
+	else
+	{
+		return variant;
+	}
+}
+
+void Resource::reportResult()
+{
+	for (ResourceObserver *observer : m_observers)
+	{
+		observer->resourceUpdated();
+	}
+}
+void Resource::reportFailure(const QString &reason)
+{
+	for (ResourceObserver *observer : m_observers)
+	{
+		observer->setFailure(reason);
+	}
+}
+void Resource::reportProgress(const int progress)
+{
+	for (ResourceObserver *observer : m_observers)
+	{
+		observer->setProgress(progress);
+	}
+}
+
+void Resource::notifyObserverDeleted(ResourceObserver *observer)
+{
+	m_observers.removeAll(observer);
+}
diff --git a/logic/resources/Resource.h b/logic/resources/Resource.h
new file mode 100644
index 00000000..d566b2a2
--- /dev/null
+++ b/logic/resources/Resource.h
@@ -0,0 +1,116 @@
+#pragma once
+
+#include <QString>
+#include <QMap>
+#include <QVariant>
+#include <functional>
+#include <memory>
+
+#include "ResourceObserver.h"
+
+class ResourceHandler;
+
+namespace Detail
+{
+template <typename T> struct Function : public Function<decltype(&T::operator())> {};
+template <typename Ret, typename Arg> struct Function<Ret(*)(Arg)> : public Function<Ret(Arg)> {};
+template <typename Ret, typename Arg> struct Function<Ret(Arg)>
+{
+	using ReturnType = Ret;
+	using Argument = Arg;
+};
+template <class C, typename Ret, typename Arg> struct Function<Ret(C::*)(Arg)> : public Function<Ret(Arg)> {};
+template <class C, typename Ret, typename Arg> struct Function<Ret(C::*)(Arg) const> : public Function<Ret(Arg)> {};
+template <typename F> struct Function<F&> : public Function<F> {};
+template <typename F> struct Function<F&&> : public Function<F> {};
+}
+
+/** Frontend class for resources
+ *
+ * Usage:
+ *	Resource::create("icon:noaccount")->applyTo(accountsAction);
+ *	Resource::create("web:http://asdf.com/image.png")->applyTo(imageLbl)->placeholder(Resource::create("icon:loading"));
+ *
+ * Memory management:
+ *	Resource caches ResourcePtrs using weak pointers, so while a resource is still existing
+ *	when a new resource is created the resources will be the same (including the same handler).
+ *
+ *	ResourceObservers keep a shared pointer to the resource, as does the Resource itself to it's
+ *	placeholder (if present). This means a resource stays valid while it's still used ("applied to" etc.)
+ *	by something. When nothing uses it anymore it gets deleted.
+ *
+ *	\note Always pass resource around using ResourcePtr! Copy and move constructors are disabled for a reason.
+ */
+class Resource : public std::enable_shared_from_this<Resource>
+{
+	explicit Resource(const QString &resource);
+	Resource(const Resource &) = delete;
+	Resource(Resource &&) = delete;
+public:
+	using Ptr = std::shared_ptr<Resource>;
+
+	~Resource();
+
+	/// The returned pointer needs to be stored until either Resource::then is called, or it is used as the argument to Resource::placeholder.
+	static Ptr create(const QString &resource);
+
+	/// This can e.g. be used to set a local icon as the placeholder while a slow (remote) icon is fetched
+	Ptr placeholder(Ptr other);
+
+	/// Use these functions to specify what should happen when e.g. the resource changes
+	Ptr applyTo(ResourceObserver *observer);
+	Ptr applyTo(QObject *target, const char *property = nullptr);
+	template<typename Func>
+	Ptr then(Func &&func)
+	{
+		using Arg = typename std::remove_cv<
+			typename std::remove_reference<typename Detail::Function<Func>::Argument>::type
+		>::type;
+		return applyTo(new FunctionResourceObserver<
+					   typename Detail::Function<Func>::ReturnType,
+					   Arg, Func
+					   >(std::forward<Func>(func)));
+	}
+
+	/// Retrieve the currently active resource. If it's type is different from T a conversion will be attempted.
+	template<typename T>
+	T getResource() const { return getResourceInternal(qMetaTypeId<T>()).template value<T>(); }
+	QVariant getResourceInternal(const int typeId) const;
+
+	template<typename T>
+	static void registerHandler(const QString &id)
+	{
+		m_handlers.insert(id, [](const QString &res) { return std::make_shared<T>(res); });
+	}
+	template<typename Func>
+	static void registerTransformer(Func &&func)
+	{
+		using Out = typename Detail::Function<Func>::ReturnType;
+		using In = typename std::remove_cv<typename std::remove_reference<typename Detail::Function<Func>::Argument>::type>::type;
+		static_assert(!std::is_same<Out, In>::value, "It does not make sense to transform a value to itself");
+		m_transfomers.insert(qMakePair(qMetaTypeId<In>(), qMetaTypeId<Out>()), [func](const QVariant &in)
+		{
+			return QVariant::fromValue<Out>(func(in.value<In>()));
+		});
+	}
+
+private:
+	friend class ResourceHandler;
+	void reportResult();
+	void reportFailure(const QString &reason);
+	void reportProgress(const int progress);
+
+	friend class ResourceObserver;
+	void notifyObserverDeleted(ResourceObserver *observer);
+
+private:
+	QList<ResourceObserver *> m_observers;
+	std::shared_ptr<ResourceHandler> m_handler = nullptr;
+	Ptr m_placeholder = nullptr;
+
+	// a list of resource handler factories, registered using registerHandler
+	static QMap<QString, std::function<std::shared_ptr<ResourceHandler>(const QString &)>> m_handlers;
+	// a list of resource transformers, registered using registerTransformer
+	static QMap<QPair<int, int>, std::function<QVariant(QVariant)>> m_transfomers;
+	static QMap<QString, std::weak_ptr<Resource>> m_resources;
+};
diff --git a/logic/resources/ResourceHandler.cpp b/logic/resources/ResourceHandler.cpp
new file mode 100644
index 00000000..46a4422c
--- /dev/null
+++ b/logic/resources/ResourceHandler.cpp
@@ -0,0 +1,28 @@
+#include "ResourceHandler.h"
+
+#include "Resource.h"
+
+void ResourceHandler::setResult(const QVariant &result)
+{
+	m_result = result;
+	if (m_resource)
+	{
+		m_resource->reportResult();
+	}
+}
+
+void ResourceHandler::setFailure(const QString &reason)
+{
+	if (m_resource)
+	{
+		m_resource->reportFailure(reason);
+	}
+}
+
+void ResourceHandler::setProgress(const int progress)
+{
+	if (m_resource)
+	{
+		m_resource->reportProgress(progress);
+	}
+}
diff --git a/logic/resources/ResourceHandler.h b/logic/resources/ResourceHandler.h
new file mode 100644
index 00000000..c1105efc
--- /dev/null
+++ b/logic/resources/ResourceHandler.h
@@ -0,0 +1,33 @@
+#pragma once
+
+#include <QVariant>
+#include <memory>
+
+class Resource;
+
+/** Base class for things that can retrieve a resource.
+ *
+ * Subclass, provide a constructor that takes a single QString as argument, and
+ * call Resource::registerHandler<MyResourceHandler>("<id>"), where <id> is the
+ * prefix of the resource ("web", "icon", etc.)
+ */
+class ResourceHandler
+{
+public:
+	virtual ~ResourceHandler() {}
+
+	void setResource(Resource *resource) { m_resource = resource; }
+	// reimplement this if you need to do something after you have been put in a shared pointer
+	virtual void init(std::shared_ptr<ResourceHandler>&) {}
+
+	QVariant result() const { return m_result; }
+
+protected: // use these methods to notify the resource of changes
+	void setResult(const QVariant &result);
+	void setFailure(const QString &reason);
+	void setProgress(const int progress);
+
+private:
+	QVariant m_result;
+	Resource *m_resource = nullptr;
+};
diff --git a/logic/resources/ResourceObserver.cpp b/logic/resources/ResourceObserver.cpp
new file mode 100644
index 00000000..4f168fd2
--- /dev/null
+++ b/logic/resources/ResourceObserver.cpp
@@ -0,0 +1,55 @@
+#include "ResourceObserver.h"
+
+#include <QDebug>
+
+#include "Resource.h"
+
+static const char *defaultPropertyForTarget(QObject *target)
+{
+	if (target->inherits("QLabel"))
+	{
+		return "pixmap";
+	}
+	else if (target->inherits("QAction") ||
+			 target->inherits("QMenu") ||
+			 target->inherits("QAbstractButton"))
+	{
+		return "icon";
+	}
+	// for unit tests
+	else if (target->inherits("DummyObserverObject"))
+	{
+		return "property";
+	}
+	else
+	{
+		Q_ASSERT_X(false, "ResourceObserver.cpp: defaultPropertyForTarget", "Unrecognized QObject subclass");
+		return nullptr;
+	}
+}
+
+QObjectResourceObserver::QObjectResourceObserver(QObject *target, const char *property)
+	: QObject(target), m_target(target)
+{
+	const QMetaObject *mo = m_target->metaObject();
+	m_property = mo->property(mo->indexOfProperty(
+								  property ?
+									  property
+									: defaultPropertyForTarget(target)));
+}
+void QObjectResourceObserver::resourceUpdated()
+{
+	m_property.write(m_target, getInternal(m_property.type()));
+}
+
+
+ResourceObserver::~ResourceObserver()
+{
+	m_resource->notifyObserverDeleted(this);
+}
+
+QVariant ResourceObserver::getInternal(const int typeId) const
+{
+	Q_ASSERT(m_resource);
+	return m_resource->getResourceInternal(typeId);
+}
diff --git a/logic/resources/ResourceObserver.h b/logic/resources/ResourceObserver.h
new file mode 100644
index 00000000..27430d42
--- /dev/null
+++ b/logic/resources/ResourceObserver.h
@@ -0,0 +1,67 @@
+#pragma once
+
+#include <memory>
+#include <functional>
+
+#include <QObject>
+#include <QMetaProperty>
+
+class QVariant;
+class Resource;
+
+/// Base class for things that can use a resource
+class ResourceObserver
+{
+public:
+	virtual ~ResourceObserver();
+
+protected: // these methods are called by the Resource when something changes
+	virtual void resourceUpdated() = 0;
+	virtual void setFailure(const QString &) {}
+	virtual void setProgress(const int) {}
+
+private:
+	friend class Resource;
+	void setSource(std::shared_ptr<Resource> resource) { m_resource = resource; }
+
+protected:
+	template<typename T>
+	T get() const { return getInternal(qMetaTypeId<T>()).template value<T>(); }
+	QVariant getInternal(const int typeId) const;
+
+private:
+	std::shared_ptr<Resource> m_resource;
+};
+
+/** Observer for QObject properties
+ *
+ * Give it a target and the name of a property, and that property will be set when the resource changes.
+ *
+ * If no name is given an attempt to find a default property for some common classes is done.
+ */
+class QObjectResourceObserver : public QObject, public ResourceObserver
+{
+public:
+	explicit QObjectResourceObserver(QObject *target, const char *property = nullptr);
+
+	void resourceUpdated() override;
+
+private:
+	QObject *m_target;
+	QMetaProperty m_property;
+};
+
+template <typename Ret, typename Arg, typename Func>
+class FunctionResourceObserver : public ResourceObserver
+{
+	std::function<Ret(Arg)> m_function;
+public:
+	template <typename T>
+	explicit FunctionResourceObserver(T &&func)
+		: m_function(std::forward<Func>(func)) {}
+
+	void resourceUpdated() override
+	{
+		m_function(get<Arg>());
+	}
+};
diff --git a/logic/resources/ResourceProxyModel.cpp b/logic/resources/ResourceProxyModel.cpp
new file mode 100644
index 00000000..6ff11367
--- /dev/null
+++ b/logic/resources/ResourceProxyModel.cpp
@@ -0,0 +1,103 @@
+#include "ResourceProxyModel.h"
+
+#include <QItemSelectionRange>
+
+#include "Resource.h"
+#include "ResourceObserver.h"
+
+//Q_DECLARE_METATYPE(QVector<int>)
+
+class ModelResourceObserver : public ResourceObserver
+{
+public:
+	explicit ModelResourceObserver(const QModelIndex &index, const int role)
+		: m_index(index), m_role(role)
+	{
+		qRegisterMetaType<QVector<int>>("QVector<int>");
+	}
+
+	void resourceUpdated() override
+	{
+		if (m_index.isValid())
+		{
+			QMetaObject::invokeMethod(const_cast<QAbstractItemModel *>(m_index.model()),
+									  "dataChanged", Qt::QueuedConnection,
+									  Q_ARG(QModelIndex, m_index), Q_ARG(QModelIndex, m_index), Q_ARG(QVector<int>, QVector<int>() << m_role));
+		}
+	}
+
+private:
+	QPersistentModelIndex m_index;
+	int m_role;
+};
+
+ResourceProxyModel::ResourceProxyModel(const int resultTypeId, QObject *parent)
+	: QIdentityProxyModel(parent), m_resultTypeId(resultTypeId)
+{
+}
+
+QVariant ResourceProxyModel::data(const QModelIndex &proxyIndex, int role) const
+{
+	const QModelIndex mapped = mapToSource(proxyIndex);
+	if (mapped.isValid() && role == Qt::DecorationRole && !mapToSource(proxyIndex).data(role).toString().isEmpty())
+	{
+		if (!m_resources.contains(mapped))
+		{
+			Resource::Ptr res = Resource::create(mapToSource(proxyIndex).data(role).toString())
+					->applyTo(new ModelResourceObserver(proxyIndex, role));
+
+			const QVariant placeholder = mapped.data(PlaceholderRole);
+			if (!placeholder.isNull() && placeholder.type() == QVariant::String)
+			{
+				res->placeholder(Resource::create(placeholder.toString()));
+			}
+
+			m_resources.insert(mapped, res);
+		}
+
+		return m_resources.value(mapped)->getResourceInternal(m_resultTypeId);
+	}
+	return mapped.data(role);
+}
+
+void ResourceProxyModel::setSourceModel(QAbstractItemModel *model)
+{
+	if (sourceModel())
+	{
+		disconnect(sourceModel(), 0, this, 0);
+	}
+	if (model)
+	{
+		connect(model, &QAbstractItemModel::dataChanged, this, [this](const QModelIndex &tl, const QModelIndex &br, const QVector<int> &roles)
+		{
+			if (roles.contains(Qt::DecorationRole) || roles.isEmpty())
+			{
+				const QItemSelectionRange range(tl, br);
+				for (const QModelIndex &index : range.indexes())
+				{
+					m_resources.remove(index);
+				}
+			}
+			else if (roles.contains(PlaceholderRole))
+			{
+				const QItemSelectionRange range(tl, br);
+				for (const QModelIndex &index : range.indexes())
+				{
+					if (m_resources.contains(index))
+					{
+						const QVariant placeholder = index.data(PlaceholderRole);
+						if (!placeholder.isNull() && placeholder.type() == QVariant::String)
+						{
+							m_resources.value(index)->placeholder(Resource::create(placeholder.toString()));
+						}
+						else
+						{
+							m_resources.value(index)->placeholder(nullptr);
+						}
+					}
+				}
+			}
+		});
+	}
+	QIdentityProxyModel::setSourceModel(model);
+}
diff --git a/logic/resources/ResourceProxyModel.h b/logic/resources/ResourceProxyModel.h
new file mode 100644
index 00000000..9db09545
--- /dev/null
+++ b/logic/resources/ResourceProxyModel.h
@@ -0,0 +1,36 @@
+#pragma once
+
+#include <QIdentityProxyModel>
+#include <memory>
+
+/// Convenience proxy model that transforms resource identifiers (strings) for Qt::DecorationRole into other types.
+class ResourceProxyModel : public QIdentityProxyModel
+{
+	Q_OBJECT
+public:
+	// resultTypeId is found using qMetaTypeId<T>()
+	explicit ResourceProxyModel(const int resultTypeId, QObject *parent = nullptr);
+
+	enum
+	{
+		// provide this role from your model if you want to show a placeholder
+		PlaceholderRole = Qt::UserRole + 0xabc // some random offset to not collide with other stuff
+	};
+
+	QVariant data(const QModelIndex &proxyIndex, int role) const override;
+	void setSourceModel(QAbstractItemModel *model) override;
+
+	template <typename T>
+	static QAbstractItemModel *mixin(QAbstractItemModel *model)
+	{
+		ResourceProxyModel *proxy = new ResourceProxyModel(qMetaTypeId<T>(), model);
+		proxy->setSourceModel(model);
+		return proxy;
+	}
+
+private:
+	// mutable because it needs to be available from the const data()
+	mutable QMap<QPersistentModelIndex, std::shared_ptr<class Resource>> m_resources;
+
+	const int m_resultTypeId;
+};
diff --git a/logic/resources/WebResourceHandler.cpp b/logic/resources/WebResourceHandler.cpp
new file mode 100644
index 00000000..7ced5bc6
--- /dev/null
+++ b/logic/resources/WebResourceHandler.cpp
@@ -0,0 +1,67 @@
+#include "WebResourceHandler.h"
+
+#include "net/CacheDownload.h"
+#include "net/HttpMetaCache.h"
+#include "net/NetJob.h"
+#include "FileSystem.h"
+#include "Env.h"
+
+QMap<QString, NetJob *> WebResourceHandler::m_activeDownloads;
+
+WebResourceHandler::WebResourceHandler(const QString &url)
+	: QObject(), m_url(url)
+{
+	MetaEntryPtr entry = ENV.metacache()->resolveEntry("icons", url);
+	if (!entry->stale)
+	{
+		setResultFromFile(entry->getFullPath());
+	}
+	else if (m_activeDownloads.contains(url))
+	{
+		NetJob *job = m_activeDownloads.value(url);
+		connect(job, &NetJob::succeeded, this, &WebResourceHandler::succeeded);
+		connect(job, &NetJob::failed, this, [job, this]() {setFailure(job->failReason());});
+		connect(job, &NetJob::progress, this, &WebResourceHandler::progress);
+	}
+	else
+	{
+		NetJob *job = new NetJob("Icon download");
+		job->addNetAction(CacheDownload::make(QUrl(url), entry));
+		connect(job, &NetJob::succeeded, this, &WebResourceHandler::succeeded);
+		connect(job, &NetJob::failed, this, [job, this]() {setFailure(job->failReason());});
+		connect(job, &NetJob::progress, this, &WebResourceHandler::progress);
+		connect(job, &NetJob::finished, job, [job](){m_activeDownloads.remove(m_activeDownloads.key(job));job->deleteLater();});
+		m_activeDownloads.insert(url, job);
+		job->start();
+	}
+}
+
+void WebResourceHandler::succeeded()
+{
+	MetaEntryPtr entry = ENV.metacache()->resolveEntry("icons", m_url);
+	setResultFromFile(entry->getFullPath());
+	m_activeDownloads.remove(m_activeDownloads.key(qobject_cast<NetJob *>(sender())));
+}
+void WebResourceHandler::progress(qint64 current, qint64 total)
+{
+	if (total == 0)
+	{
+		setProgress(101);
+	}
+	else
+	{
+		setProgress(current / total);
+	}
+}
+
+void WebResourceHandler::setResultFromFile(const QString &file)
+{
+	try
+	{
+		setResult(FS::read(file));
+	}
+	catch (Exception &e)
+	{
+		setFailure(e.cause());
+	}
+}
diff --git a/logic/resources/WebResourceHandler.h b/logic/resources/WebResourceHandler.h
new file mode 100644
index 00000000..88804af3
--- /dev/null
+++ b/logic/resources/WebResourceHandler.h
@@ -0,0 +1,23 @@
+#pragma once
+
+#include <QObject>
+#include "ResourceHandler.h"
+
+class NetJob;
+
+class WebResourceHandler : public QObject, public ResourceHandler
+{
+public:
+	explicit WebResourceHandler(const QString &url);
+
+private slots:
+	void succeeded();
+	void progress(qint64 current, qint64 total);
+
+private:
+	static QMap<QString, NetJob *> m_activeDownloads;
+
+	QString m_url;
+
+	void setResultFromFile(const QString &file);
+};
diff --git a/logic/tasks/StandardTask.cpp b/logic/tasks/StandardTask.cpp
new file mode 100644
index 00000000..3201d674
--- /dev/null
+++ b/logic/tasks/StandardTask.cpp
@@ -0,0 +1,120 @@
+// Licensed under the Apache-2.0 license. See README.md for details.
+
+#include "StandardTask.h"
+
+#include <QEventLoop>
+#include <QProcess>
+
+#include "net/CacheDownload.h"
+#include "net/ByteArrayDownload.h"
+#include "net/NetJob.h"
+#include "FileSystem.h"
+#include "Exception.h"
+#include "Env.h"
+
+StandardTask::StandardTask(QObject *parent)
+	: Task(parent)
+{
+	m_loop = new QEventLoop(this);
+}
+
+void StandardTask::runTask(QObjectPtr<Task> other)
+{
+	connect(other.get(), &Task::succeeded, m_loop, &QEventLoop::quit);
+	connect(other.get(), &Task::failed, m_loop, &QEventLoop::quit);
+	connect(other.get(), &Task::progress, this, [this](qint64 current, qint64 total){setProgress(current / total);});
+	connect(other.get(), &Task::status, this, &StandardTask::setStatus);
+	if (!other->isRunning())
+	{
+		other->start();
+	}
+	if (other->isRunning())
+	{
+		m_loop->exec();
+	}
+	disconnect(other.get(), 0, m_loop, 0);
+	disconnect(other.get(), 0, this, 0);
+	other->deleteLater();
+	if (!other->successful())
+	{
+		throw Exception(other->failReason());
+	}
+}
+void StandardTask::runTaskNonBlocking(QObjectPtr<Task> other)
+{
+	if (!other)
+	{
+		return;
+	}
+	m_pendingTasks.append(other.get());
+	m_pendingTaskPtrs.append(other);
+	other->start();
+}
+QByteArray StandardTask::networkGet(const QUrl &url)
+{
+	ByteArrayDownloadPtr task = ByteArrayDownload::make(url);
+	runTask(wrapDownload("", task));
+	return task->m_data;
+}
+QByteArray StandardTask::networkGetCached(const QString &name, const QString &base, const QString &path, const QUrl &url, const bool alwaysRefetch,
+										  INetworkValidator *validator)
+{
+	MetaEntryPtr entry = ENV.metacache()->resolveEntry(base, path);
+	if (!alwaysRefetch && !entry->stale)
+	{
+		if (validator) { delete validator; }
+		return FS::read(entry->getFullPath());
+	}
+	else if (alwaysRefetch)
+	{
+		entry->stale = true;
+	}
+	CacheDownloadPtr task = CacheDownload::make(url, entry);
+	task->setValidator(validator);
+	runTask(wrapDownload(name, task));
+	return FS::read(entry->getFullPath());
+}
+QByteArray StandardTask::networkGetCached(const QString &name, const QString &base, const QString &path, const QUrl &url, const QMap<QString, QString> &headers,
+										  INetworkValidator *validator)
+{
+	MetaEntryPtr entry = ENV.metacache()->resolveEntry(base, path);
+	if (!entry->stale)
+	{
+		if (validator) { delete validator; }
+		return FS::read(entry->getFullPath());
+	}
+	CacheDownloadPtr task = CacheDownload::make(url, entry);
+	//task->setHeaders(headers);
+	task->setValidator(validator);
+	runTask(wrapDownload(name, task));
+	return FS::read(entry->getFullPath());
+}
+void StandardTask::networkGetCachedNonBlocking(const QString &name, const QString &base, const QString &path, const QUrl &url, const bool alwaysRefetch,
+											   INetworkValidator *validator)
+{
+	MetaEntryPtr entry = ENV.metacache()->resolveEntry(base, path);
+	if (!alwaysRefetch && !entry->stale)
+	{
+		return;
+	}
+	CacheDownloadPtr dl = CacheDownload::make(url, entry);
+	dl->setValidator(validator);
+	runTaskNonBlocking(wrapDownload(name, dl));
+}
+void StandardTask::waitOnPending()
+{
+	for (int i = 0; i < m_pendingTasks.size(); ++i)
+	{
+		if (m_pendingTasks.at(i) && m_pendingTasks.at(i)->isRunning())
+		{
+			runTask(m_pendingTaskPtrs.at(i));
+		}
+	}
+}
+
+QObjectPtr<NetJob> StandardTask::wrapDownload(const QString &name, std::shared_ptr<NetAction> action)
+{
+	NetJobPtr task = NetJobPtr(new NetJob(name));
+	task->addNetAction(action);
+	return task;
+}
diff --git a/logic/tasks/StandardTask.h b/logic/tasks/StandardTask.h
new file mode 100644
index 00000000..6f283dcd
--- /dev/null
+++ b/logic/tasks/StandardTask.h
@@ -0,0 +1,43 @@
+// Licensed under the Apache-2.0 license. See README.md for details.
+
+#pragma once
+
+#include "Task.h"
+
+#include <QPointer>
+#include <memory>
+
+#include "QObjectPtr.h"
+
+class QEventLoop;
+class QDir;
+class NetAction;
+class NetJob;
+class INetworkValidator;
+
+class StandardTask : public Task
+{
+	Q_OBJECT
+public:
+	explicit StandardTask(QObject *parent = nullptr);
+
+protected:
+	// TODO: switch to a future-based system
+	void runTask(QObjectPtr<Task> other);
+	void runTaskNonBlocking(QObjectPtr<Task> other);
+	QByteArray networkGet(const QUrl &url);
+	QByteArray networkGetCached(const QString &name, const QString &base, const QString &path, const QUrl &url, const bool alwaysRefetch = false,
+								INetworkValidator *validator = nullptr);
+	QByteArray networkGetCached(const QString &name, const QString &base, const QString &path, const QUrl &url, const QMap<QString, QString> &headers,
+								INetworkValidator *validator = nullptr);
+	void networkGetCachedNonBlocking(const QString &name, const QString &base, const QString &path, const QUrl &url, const bool alwaysRefetch = false,
+									 INetworkValidator *validator = nullptr);
+	void waitOnPending();
+
+private:
+	QEventLoop *m_loop;
+	QList<QPointer<Task>> m_pendingTasks; // only used to check if the object was deleted
+	QList<QObjectPtr<Task>> m_pendingTaskPtrs;
+
+	QObjectPtr<NetJob> wrapDownload(const QString &name, std::shared_ptr<NetAction> action);
+};
diff --git a/logic/tasks/Task.cpp b/logic/tasks/Task.cpp
index 8fed810b..eaeff4c2 100644
--- a/logic/tasks/Task.cpp
+++ b/logic/tasks/Task.cpp
@@ -14,6 +14,7 @@
  */
 
 #include "Task.h"
+
 #include <QDebug>
 
 Task::Task(QObject *parent) : QObject(parent)
diff --git a/logic/tasks/Task.h b/logic/tasks/Task.h
index 3ab85d7d..93ca620d 100644
--- a/logic/tasks/Task.h
+++ b/logic/tasks/Task.h
@@ -39,6 +39,8 @@ public:
 	 */
 	virtual QString failReason() const;
 
+	virtual bool canAbort() const { return false; }
+
 signals:
 	void started();
 	void progress(qint64 current, qint64 total);