Add instance copying, fix instance creation (with identical names)

CMakeLists.txt

@@ -183,6 +183,8 @@ gui/mainwindow.h
 gui/mainwindow.cpp
 gui/settingsdialog.h
 gui/settingsdialog.cpp
+gui/CopyInstanceDialog.h
+gui/CopyInstanceDialog.cpp
 gui/newinstancedialog.h
 gui/newinstancedialog.cpp
 gui/logindialog.h
@@ -332,6 +334,7 @@ logic/NagUtils.cpp
 SET(MULTIMC_UIS
 gui/mainwindow.ui
 gui/settingsdialog.ui
+gui/CopyInstanceDialog.ui
 gui/newinstancedialog.ui
 gui/logindialog.ui
 gui/aboutdialog.ui

depends/util/src/pathutils.cpp

@@ -149,3 +149,5 @@ void openFileInDefaultProgram ( QString filename )
 {
 	QDesktopServices::openUrl ( "file:///" + QFileInfo ( filename ).absolutePath() );
 }
+
+

gui/CopyInstanceDialog.cpp

@@ -0,0 +1,84 @@
+/* Copyright 2013 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <MultiMC.h>
+#include "CopyInstanceDialog.h"
+#include "ui_CopyInstanceDialog.h"
+
+#include "logic/InstanceFactory.h"
+#include "logic/BaseVersion.h"
+#include "logic/lists/IconList.h"
+#include "logic/lists/MinecraftVersionList.h"
+#include "logic/tasks/Task.h"
+#include <logic/BaseInstance.h>
+
+#include "gui/platform.h"
+#include "versionselectdialog.h"
+#include "ProgressDialog.h"
+#include "IconPickerDialog.h"
+
+#include <QLayout>
+#include <QPushButton>
+
+CopyInstanceDialog::CopyInstanceDialog(BaseInstance *original, QWidget *parent)
+	: m_original(original), QDialog(parent), ui(new Ui::CopyInstanceDialog)
+{
+	MultiMCPlatform::fixWM_CLASS(this);
+	ui->setupUi(this);
+	resize(minimumSizeHint());
+	layout()->setSizeConstraint(QLayout::SetFixedSize);
+
+	InstIconKey = original->iconKey();
+	ui->iconButton->setIcon(MMC->icons()->getIcon(InstIconKey));
+	ui->instNameTextBox->setText(original->name());
+	ui->instNameTextBox->setFocus();
+}
+
+CopyInstanceDialog::~CopyInstanceDialog()
+{
+	delete ui;
+}
+
+void CopyInstanceDialog::updateDialogState()
+{
+	ui->buttonBox->button(QDialogButtonBox::Ok)->setEnabled(!instName().isEmpty());
+}
+
+QString CopyInstanceDialog::instName() const
+{
+	return ui->instNameTextBox->text();
+}
+
+QString CopyInstanceDialog::iconKey() const
+{
+	return InstIconKey;
+}
+
+void CopyInstanceDialog::on_iconButton_clicked()
+{
+	IconPickerDialog dlg(this);
+	dlg.exec(InstIconKey);
+
+	if (dlg.result() == QDialog::Accepted)
+	{
+		InstIconKey = dlg.selectedIconKey;
+		ui->iconButton->setIcon(MMC->icons()->getIcon(InstIconKey));
+	}
+}
+
+void CopyInstanceDialog::on_instNameTextBox_textChanged(const QString &arg1)
+{
+	updateDialogState();
+}

gui/CopyInstanceDialog.h

@@ -0,0 +1,50 @@
+/* Copyright 2013 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <QDialog>
+#include "logic/BaseVersion.h"
+
+class BaseInstance;
+
+namespace Ui
+{
+class CopyInstanceDialog;
+}
+
+class CopyInstanceDialog : public QDialog
+{
+	Q_OBJECT
+
+public:
+	explicit CopyInstanceDialog(BaseInstance *original, QWidget *parent = 0);
+	~CopyInstanceDialog();
+
+	void updateDialogState();
+
+	QString instName() const;
+	QString iconKey() const;
+
+private
+slots:
+	void on_iconButton_clicked();
+	void on_instNameTextBox_textChanged(const QString &arg1);
+
+private:
+	Ui::CopyInstanceDialog *ui;
+	QString InstIconKey;
+	BaseInstance *m_original;
+};

gui/CopyInstanceDialog.ui

@@ -0,0 +1,134 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<ui version="4.0">
+ <class>CopyInstanceDialog</class>
+ <widget class="QDialog" name="CopyInstanceDialog">
+  <property name="windowModality">
+   <enum>Qt::ApplicationModal</enum>
+  </property>
+  <property name="geometry">
+   <rect>
+    <x>0</x>
+    <y>0</y>
+    <width>345</width>
+    <height>205</height>
+   </rect>
+  </property>
+  <property name="windowTitle">
+   <string>Copy Instance</string>
+  </property>
+  <property name="windowIcon">
+   <iconset resource="../multimc.qrc">
+    <normaloff>:/icons/toolbar/copy</normaloff>:/icons/toolbar/copy</iconset>
+  </property>
+  <property name="modal">
+   <bool>true</bool>
+  </property>
+  <layout class="QVBoxLayout" name="verticalLayout">
+   <item>
+    <layout class="QHBoxLayout" name="iconBtnLayout">
+     <item>
+      <spacer name="iconBtnLeftSpacer">
+       <property name="orientation">
+        <enum>Qt::Horizontal</enum>
+       </property>
+       <property name="sizeHint" stdset="0">
+        <size>
+         <width>40</width>
+         <height>20</height>
+        </size>
+       </property>
+      </spacer>
+     </item>
+     <item>
+      <widget class="QToolButton" name="iconButton">
+       <property name="icon">
+        <iconset resource="../multimc.qrc">
+         <normaloff>:/icons/instances/infinity</normaloff>:/icons/instances/infinity</iconset>
+       </property>
+       <property name="iconSize">
+        <size>
+         <width>80</width>
+         <height>80</height>
+        </size>
+       </property>
+      </widget>
+     </item>
+     <item>
+      <spacer name="iconBtnRightSpacer">
+       <property name="orientation">
+        <enum>Qt::Horizontal</enum>
+       </property>
+       <property name="sizeHint" stdset="0">
+        <size>
+         <width>40</width>
+         <height>20</height>
+        </size>
+       </property>
+      </spacer>
+     </item>
+    </layout>
+   </item>
+   <item>
+    <widget class="QLineEdit" name="instNameTextBox">
+     <property name="placeholderText">
+      <string>Name</string>
+     </property>
+    </widget>
+   </item>
+   <item>
+    <widget class="Line" name="line">
+     <property name="orientation">
+      <enum>Qt::Horizontal</enum>
+     </property>
+    </widget>
+   </item>
+   <item>
+    <widget class="QDialogButtonBox" name="buttonBox">
+     <property name="orientation">
+      <enum>Qt::Horizontal</enum>
+     </property>
+     <property name="standardButtons">
+      <set>QDialogButtonBox::Cancel|QDialogButtonBox::Ok</set>
+     </property>
+    </widget>
+   </item>
+  </layout>
+ </widget>
+ <resources>
+  <include location="../multimc.qrc"/>
+ </resources>
+ <connections>
+  <connection>
+   <sender>buttonBox</sender>
+   <signal>accepted()</signal>
+   <receiver>CopyInstanceDialog</receiver>
+   <slot>accept()</slot>
+   <hints>
+    <hint type="sourcelabel">
+     <x>248</x>
+     <y>254</y>
+    </hint>
+    <hint type="destinationlabel">
+     <x>157</x>
+     <y>274</y>
+    </hint>
+   </hints>
+  </connection>
+  <connection>
+   <sender>buttonBox</sender>
+   <signal>rejected()</signal>
+   <receiver>CopyInstanceDialog</receiver>
+   <slot>reject()</slot>
+   <hints>
+    <hint type="sourcelabel">
+     <x>316</x>
+     <y>260</y>
+    </hint>
+    <hint type="destinationlabel">
+     <x>286</x>
+     <y>274</y>
+    </hint>
+   </hints>
+  </connection>
+ </connections>
+</ui>

gui/mainwindow.cpp

@@ -74,6 +74,7 @@
 #include "IconPickerDialog.h"
 #include "LabeledToolButton.h"
 #include "EditNotesDialog.h"
+#include "CopyInstanceDialog.h"
 
 MainWindow::MainWindow(QWidget *parent) : QMainWindow(parent), ui(new Ui::MainWindow)
 {
@@ -91,7 +92,9 @@ MainWindow::MainWindow(QWidget *parent) : QMainWindow(parent), ui(new Ui::MainWi
 
 	// The instance action toolbar customizations
 	{
+		// disabled until we have an instance selected
 		ui->instanceToolBar->setEnabled(false);
+
 		// the rename label is inside the rename tool button
 		renameButton = new LabeledToolButton();
 		renameButton->setText("Instance Name");
@@ -267,8 +270,9 @@ void MainWindow::on_actionAddInstance_triggered()
 
 	BaseInstance *newInstance = NULL;
 
-	QString instDirName = DirNameFromString(newInstDlg.instName());
+	QString instancesDir = MMC->settings()->get("InstanceDir").toString();
-	QString instDir = PathCombine(MMC->settings()->get("InstanceDir").toString(), instDirName);
+	QString instDirName = DirNameFromString(newInstDlg.instName(), instancesDir);
+	QString instDir = PathCombine(instancesDir, instDirName);
 
 	auto &loader = InstanceFactory::get();
 
@@ -305,6 +309,56 @@ void MainWindow::on_actionAddInstance_triggered()
 	}
 }
 
+void MainWindow::on_actionCopyInstance_triggered()
+{
+	if (!m_selectedInstance)
+		return;
+
+	CopyInstanceDialog copyInstDlg(m_selectedInstance, this);
+	if (!copyInstDlg.exec())
+		return;
+
+	QString instancesDir = MMC->settings()->get("InstanceDir").toString();
+	QString instDirName = DirNameFromString(copyInstDlg.instName(), instancesDir);
+	QString instDir = PathCombine(instancesDir, instDirName);
+
+	auto &loader = InstanceFactory::get();
+
+	BaseInstance *newInstance = NULL;
+	auto error = loader.copyInstance(newInstance, m_selectedInstance, instDir);
+
+	QString errorMsg = QString("Failed to create instance %1: ").arg(instDirName);
+	switch (error)
+	{
+	case InstanceFactory::NoCreateError:
+		newInstance->setName(copyInstDlg.instName());
+		newInstance->setIconKey(copyInstDlg.iconKey());
+		MMC->instances()->add(InstancePtr(newInstance));
+		return;
+
+	case InstanceFactory::InstExists:
+	{
+		errorMsg += "An instance with the given directory name already exists.";
+		CustomMessageBox::selectable(this, tr("Error"), errorMsg, QMessageBox::Warning)->show();
+		break;
+	}
+
+	case InstanceFactory::CantCreateDir:
+	{
+		errorMsg += "Failed to create the instance directory.";
+		CustomMessageBox::selectable(this, tr("Error"), errorMsg, QMessageBox::Warning)->show();
+		break;
+	}
+
+	default:
+	{
+		errorMsg += QString("Unknown instance loader error %1").arg(error);
+		CustomMessageBox::selectable(this, tr("Error"), errorMsg, QMessageBox::Warning)->show();
+		break;
+	}
+	}
+}
+
 void MainWindow::on_actionChangeInstIcon_triggered()
 {
 	if (!m_selectedInstance)
@@ -395,10 +449,10 @@ void MainWindow::on_actionDeleteInstance_triggered()
 {
 	if (m_selectedInstance)
 	{
-		auto response = CustomMessageBox::selectable(this, tr("CAREFUL"),
+		auto response = CustomMessageBox::selectable(
-													 tr("This is permanent! Are you sure?\nAbout to delete: ")
+			this, tr("CAREFUL"), tr("This is permanent! Are you sure?\nAbout to delete: ") +
-													 + m_selectedInstance->name(),
+									 m_selectedInstance->name(),
-													 QMessageBox::Question, QMessageBox::Yes | QMessageBox::No)->exec();
+			QMessageBox::Question, QMessageBox::Yes | QMessageBox::No)->exec();
 		if (response == QMessageBox::Yes)
 		{
 			m_selectedInstance->nuke();
@@ -640,7 +694,8 @@ void MainWindow::onGameUpdateComplete()
 
 void MainWindow::onGameUpdateError(QString error)
 {
-	CustomMessageBox::selectable(this, tr("Error updating instance"), error, QMessageBox::Warning)->show();
+	CustomMessageBox::selectable(this, tr("Error updating instance"), error,
+								 QMessageBox::Warning)->show();
 }
 
 void MainWindow::launchInstance(BaseInstance *instance, LoginResponse response)
@@ -709,9 +764,10 @@ void MainWindow::on_actionMakeDesktopShortcut_triggered()
 						 QStringList() << "-dl" << QDir::currentPath() << "test", name,
 						 "application-x-octet-stream");
 
-	CustomMessageBox::selectable(this, tr("Not useful"),
+	CustomMessageBox::selectable(
-								 tr("A Dummy Shortcut was created. it will not do anything productive"),
+		this, tr("Not useful"),
-								 QMessageBox::Warning)->show();
+		tr("A Dummy Shortcut was created. it will not do anything productive"),
+		QMessageBox::Warning)->show();
 }
 
 // BrowserDialog
@@ -732,10 +788,11 @@ void MainWindow::on_actionChangeInstMCVersion_triggered()
 	{
 		if (m_selectedInstance->versionIsCustom())
 		{
-			auto result = CustomMessageBox::selectable(this, tr("Are you sure?"),
+			auto result = CustomMessageBox::selectable(
-										 tr("This will remove any library/version customization you did previously. "
+				this, tr("Are you sure?"),
-											"This includes things like Forge install and similar."),
+				tr("This will remove any library/version customization you did previously. "
-										 QMessageBox::Warning, QMessageBox::Ok, QMessageBox::Abort)->exec();
+				   "This includes things like Forge install and similar."),
+				QMessageBox::Warning, QMessageBox::Ok, QMessageBox::Abort)->exec();
 
 			if (result != QMessageBox::Ok)
 				return;
@@ -867,11 +924,12 @@ void MainWindow::checkSetDefaultJava()
 			java = std::dynamic_pointer_cast<JavaVersion>(vselect.selectedVersion());
 		else
 		{
-			CustomMessageBox::selectable(this, tr("Invalid version selected"),
+			CustomMessageBox::selectable(
-										 tr("You didn't select a valid Java version, so MultiMC will "
+				this, tr("Invalid version selected"),
-											"select the default. "
+				tr("You didn't select a valid Java version, so MultiMC will "
-											"You can change this in the settings dialog."),
+				   "select the default. "
-										 QMessageBox::Warning)->show();
+				   "You can change this in the settings dialog."),
+				QMessageBox::Warning)->show();
 
 			JavaUtils ju;
 			java = ju.GetDefaultJava();

gui/mainwindow.h

@@ -22,6 +22,7 @@
 #include "logic/net/LoginTask.h"
 #include "logic/BaseInstance.h"
 
+class QToolButton;
 class LabeledToolButton;
 class QLabel;
 class InstanceProxyModel;
@@ -51,13 +52,16 @@ public:
 
 	void checkSetDefaultJava();
 
-private slots:
+private
+slots:
 	void onCatToggled(bool);
 
 	void on_actionAbout_triggered();
 
 	void on_actionAddInstance_triggered();
 
+	void on_actionCopyInstance_triggered();
+
 	void on_actionChangeInstGroup_triggered();
 
 	void on_actionChangeInstIcon_triggered();
@@ -122,7 +126,8 @@ private slots:
 	void assetsFailed();
 	void assetsFinished();
 
-public slots:
+public
+slots:
 	void instanceActivated(QModelIndex);
 
 	void instanceChanged(const QModelIndex &current, const QModelIndex &previous);
@@ -146,6 +151,7 @@ private:
 	ConsoleWindow *console;
 	OneSixAssets *assets_downloader;
 	LabeledToolButton *renameButton;
+	QToolButton *changeIconButton;
 
 	BaseInstance *m_selectedInstance;
 

gui/mainwindow.ui

@@ -62,6 +62,8 @@
     <bool>false</bool>
    </attribute>
    <addaction name="actionAddInstance"/>
+   <addaction name="actionCopyInstance"/>
+   <addaction name="separator"/>
    <addaction name="actionViewInstanceFolder"/>
    <addaction name="actionViewCentralModsFolder"/>
    <addaction name="actionRefresh"/>
@@ -310,6 +312,9 @@
    <property name="statusTip">
     <string>Change the selected instance's icon.</string>
    </property>
+   <property name="iconVisibleInMenu">
+    <bool>true</bool>
+   </property>
   </action>
   <action name="actionEditInstNotes">
    <property name="text">
@@ -445,6 +450,21 @@
     <string>&lt;html&gt;&lt;head/&gt;&lt;body&gt;&lt;p align=&quot;center&quot;&gt;&lt;span style=&quot; font-weight:600; color:#ff0004;&quot;&gt;Catnarok!&lt;/span&gt;&lt;/p&gt;&lt;p align=&quot;center&quot;&gt;Or just a cat with a ball of yarn?&lt;/p&gt;&lt;p align=&quot;center&quot;&gt;&lt;span style=&quot; font-style:italic;&quot;&gt;WHO KNOWS?!&lt;/span&gt;&lt;/p&gt;&lt;p align=&quot;center&quot;&gt;&lt;img src=&quot;:/icons/instances/tnt&quot;/&gt;&lt;/p&gt;&lt;/body&gt;&lt;/html&gt;</string>
    </property>
   </action>
+  <action name="actionCopyInstance">
+   <property name="icon">
+    <iconset resource="../multimc.qrc">
+     <normaloff>:/icons/toolbar/copy</normaloff>:/icons/toolbar/copy</iconset>
+   </property>
+   <property name="text">
+    <string>Copy Instance</string>
+   </property>
+   <property name="toolTip">
+    <string>Copy the selected instance.</string>
+   </property>
+   <property name="statusTip">
+    <string>Add a new instance.</string>
+   </property>
+  </action>
  </widget>
  <layoutdefault spacing="6" margin="11"/>
  <resources>

gui/newinstancedialog.h

@@ -13,13 +13,13 @@
  * limitations under the License.
  */
 
-#ifndef NEWINSTANCEDIALOG_H
+#pragma once
-#define NEWINSTANCEDIALOG_H
 
 #include <QDialog>
 #include "logic/BaseVersion.h"
 
-namespace Ui {
+namespace Ui
+{
 class NewInstanceDialog;
 }
 
@@ -41,7 +41,8 @@ public:
 	QString iconKey() const;
 	BaseVersionPtr selectedVersion() const;
 
-private slots:
+private
+slots:
 	void on_btnChangeVersion_clicked();
 	void on_iconButton_clicked();
 	void on_instNameTextBox_textChanged(const QString &arg1);
@@ -52,5 +53,3 @@ private:
 	BaseVersionPtr m_selectedVersion;
 	QString InstIconKey;
 };
-
-#endif // NEWINSTANCEDIALOG_H

logic/InstanceFactory.cpp

@@ -34,13 +34,12 @@
 
 InstanceFactory InstanceFactory::loader;
 
-InstanceFactory::InstanceFactory() :
+InstanceFactory::InstanceFactory() : QObject(NULL)
-	QObject(NULL)
 {
-	
 }
 
-InstanceFactory::InstLoadError InstanceFactory::loadInstance(BaseInstance *&inst, const QString &instDir)
+InstanceFactory::InstLoadError InstanceFactory::loadInstance(BaseInstance *&inst,
+															 const QString &instDir)
 {
 	auto m_settings = new INISettingsObject(PathCombine(instDir, "instance.cfg"));
 
@@ -48,16 +47,16 @@ InstanceFactory::InstLoadError InstanceFactory::loadInstance(BaseInstance *&inst
 
 	QString inst_type = m_settings->get("InstanceType").toString();
 
-	//FIXME: replace with a map lookup, where instance classes register their types
+	// FIXME: replace with a map lookup, where instance classes register their types
-	if(inst_type == "Legacy")
+	if (inst_type == "Legacy")
 	{
 		inst = new LegacyInstance(instDir, m_settings, this);
 	}
-	else if(inst_type == "OneSix")
+	else if (inst_type == "OneSix")
 	{
 		inst = new OneSixInstance(instDir, m_settings, this);
 	}
-	else if(inst_type == "Nostalgia")
+	else if (inst_type == "Nostalgia")
 	{
 		inst = new NostalgiaInstance(instDir, m_settings, this);
 	}
@@ -68,8 +67,9 @@ InstanceFactory::InstLoadError InstanceFactory::loadInstance(BaseInstance *&inst
 	return NoLoadError;
 }
 
-
+InstanceFactory::InstCreateError InstanceFactory::createInstance(BaseInstance *&inst,
-InstanceFactory::InstCreateError InstanceFactory::createInstance( BaseInstance*& inst, BaseVersionPtr version, const QString& instDir )
+																 BaseVersionPtr version,
+																 const QString &instDir)
 {
 	QDir rootDir(instDir);
 
@@ -79,39 +79,69 @@ InstanceFactory::InstCreateError InstanceFactory::createInstance( BaseInstance*&
 		return InstanceFactory::CantCreateDir;
 	}
 	auto mcVer = std::dynamic_pointer_cast<MinecraftVersion>(version);
-	if(!mcVer)
+	if (!mcVer)
 		return InstanceFactory::NoSuchVersion;
 
 	auto m_settings = new INISettingsObject(PathCombine(instDir, "instance.cfg"));
 	m_settings->registerSetting(new Setting("InstanceType", "Legacy"));
 
-	switch(mcVer->type)
+	switch (mcVer->type)
 	{
-		case MinecraftVersion::Legacy:
+	case MinecraftVersion::Legacy:
-			m_settings->set("InstanceType", "Legacy");
+		m_settings->set("InstanceType", "Legacy");
-			inst = new LegacyInstance(instDir, m_settings, this);
+		inst = new LegacyInstance(instDir, m_settings, this);
-			inst->setIntendedVersionId(version->descriptor());
+		inst->setIntendedVersionId(version->descriptor());
-			inst->setShouldUseCustomBaseJar(false);
+		inst->setShouldUseCustomBaseJar(false);
-			break;
+		break;
-		case MinecraftVersion::OneSix:
+	case MinecraftVersion::OneSix:
-			m_settings->set("InstanceType", "OneSix");
+		m_settings->set("InstanceType", "OneSix");
-			inst = new OneSixInstance(instDir, m_settings, this);
+		inst = new OneSixInstance(instDir, m_settings, this);
-			inst->setIntendedVersionId(version->descriptor());
+		inst->setIntendedVersionId(version->descriptor());
-			inst->setShouldUseCustomBaseJar(false);
+		inst->setShouldUseCustomBaseJar(false);
-			break;
+		break;
-		case MinecraftVersion::Nostalgia:
+	case MinecraftVersion::Nostalgia:
-			m_settings->set("InstanceType", "Nostalgia");
+		m_settings->set("InstanceType", "Nostalgia");
-			inst = new NostalgiaInstance(instDir, m_settings, this);
+		inst = new NostalgiaInstance(instDir, m_settings, this);
-			inst->setIntendedVersionId(version->descriptor());
+		inst->setIntendedVersionId(version->descriptor());
-			inst->setShouldUseCustomBaseJar(false);
+		inst->setShouldUseCustomBaseJar(false);
-			break;
+		break;
-		default:
+	default:
-		{
+	{
-			delete m_settings;
+		delete m_settings;
-			return InstanceFactory::NoSuchVersion;
+		return InstanceFactory::NoSuchVersion;
-		}
+	}
 	}
 
-	//FIXME: really, how do you even know?
+	// FIXME: really, how do you even know?
 	return InstanceFactory::NoCreateError;
 }
+
+InstanceFactory::InstCreateError InstanceFactory::copyInstance(BaseInstance *&newInstance,
+															   BaseInstance *&oldInstance,
+															   const QString &instDir)
+{
+	QDir rootDir(instDir);
+
+	QLOG_DEBUG() << instDir.toUtf8();
+	if (!copyPath(oldInstance->instanceRoot(), instDir))
+	{
+		rootDir.removeRecursively();
+		return InstanceFactory::CantCreateDir;
+	}
+	auto error = loadInstance(newInstance, instDir);
+	switch(error)
+	{
+		case NoLoadError:
+			return NoCreateError;
+		case UnknownLoadError:
+		{
+			rootDir.removeRecursively();
+			return UnknownCreateError;
+		}
+		case NotAnInstance:
+		{
+			rootDir.removeRecursively();
+			return CantCreateDir;
+		}
+	};
+}

logic/InstanceFactory.h

@@ -34,7 +34,10 @@ public:
 	/*!
 	 * \brief Gets a reference to the instance loader.
 	 */
-	static InstanceFactory &get() { return loader; }
+	static InstanceFactory &get()
+	{
+		return loader;
+	}
 
 	enum InstLoadError
 	{
@@ -56,12 +59,27 @@ public:
 	 * \brief Creates a stub instance
 	 *
 	 * \param inst Pointer to store the created instance in.
-	 * \param instDir The instance's directory.
+	 * \param inst Game version to use for the instance
+	 * \param instDir The new instance's directory.
 	 * \return An InstCreateError error code.
 	 * - InstExists if the given instance directory is already an instance.
 	 * - CantCreateDir if the given instance directory cannot be created.
 	 */
-	InstCreateError createInstance(BaseInstance *&inst, BaseVersionPtr version, const QString &instDir);
+	InstCreateError createInstance(BaseInstance *&inst, BaseVersionPtr version,
+								   const QString &instDir);
+
+	/*!
+	 * \brief Creates a copy of an existing instance with a new name
+	 *
+	 * \param newInstance Pointer to store the created instance in.
+	 * \param oldInstance The instance to copy
+	 * \param instDir The new instance's directory.
+	 * \return An InstCreateError error code.
+	 * - InstExists if the given instance directory is already an instance.
+	 * - CantCreateDir if the given instance directory cannot be created.
+	 */
+	InstCreateError copyInstance(BaseInstance *&newInstance, BaseInstance *&oldInstance,
+								 const QString &instDir);
 
 	/*!
 	 * \brief Loads an instance from the given directory.

multimc.qrc

@@ -6,6 +6,7 @@
 		<file alias="checkupdate">resources/icons/toolbar/checkupdate.png</file>
 		<file alias="help">resources/icons/toolbar/help.png</file>
 		<file alias="new">resources/icons/toolbar/new.png</file>
+		<file alias="copy">resources/icons/toolbar/InstCopy.png</file>
 		<file alias="news">resources/icons/toolbar/NewsIcon.png</file>
 		<file alias="refresh">resources/icons/toolbar/refresh.png</file>
 		<file alias="settings">resources/icons/toolbar/settings.png</file>