/* ScummVM - Graphic Adventure Engine
 *
 * ScummVM is the legal property of its developers, whose names
 * are too numerous to list here. Please refer to the COPYRIGHT
 * file distributed with this source distribution.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

#include "engines/engine.h"
#include "engines/dialogs.h"
#include "engines/util.h"
#include "engines/metaengine.h"

#include "common/config-manager.h"
#include "common/events.h"
#include "common/file.h"
#include "common/system.h"
#include "common/str.h"
#include "common/ustr.h"
#include "common/error.h"
#include "common/list.h"
#include "common/memstream.h"
#include "common/savefile.h"
#include "common/scummsys.h"
#include "common/taskbar.h"
#include "common/textconsole.h"
#include "common/translation.h"
#include "common/singleton.h"

#include "backends/audiocd/audiocd.h"
#include "backends/keymapper/action.h"
#include "backends/keymapper/keymapper.h"
#include "base/version.h"

#include "gui/gui-manager.h"
#include "gui/debugger.h"
#include "gui/dialog.h"
#include "gui/EventRecorder.h"
#include "gui/message.h"
#include "gui/saveload.h"

#include "audio/mixer.h"

#include "graphics/cursorman.h"
#include "graphics/fontman.h"
#include "graphics/paletteman.h"
#include "graphics/pixelformat.h"
#include "image/bmp.h"

#include "common/text-to-speech.h"

// FIXME: HACK for error()
Engine *g_engine = 0;
bool Engine::_quitRequested;

// Output formatter for debug() and error() which invokes
// the errorString method of the active engine, if any.
static void defaultOutputFormatter(char *dst, const char *src, size_t dstSize) {
	if (g_engine) {
		g_engine->errorString(src, dst, dstSize);
	} else {
		Common::strlcpy(dst, src, dstSize);
	}
}

static bool defaultErrorHandler(const char *msg) {
	bool handled = false;

	// Unless this error -originated- within the debugger itself, we
	// now invoke the debugger, if available / supported.
	if (g_engine) {
		GUI::Debugger *debugger = g_engine->getOrCreateDebugger();

#if defined(USE_TASKBAR)
		g_system->getTaskbarManager()->notifyError();
#endif

		if (debugger && !debugger->isActive()) {
			debugger->attach(msg);
			debugger->onFrame();
			handled = true;
		}


#if defined(USE_TASKBAR)
		g_system->getTaskbarManager()->clearError();
#endif

	}

	return handled;
}

// Chained games manager

ChainedGamesManager::ChainedGamesManager() {
	clear();
}

void ChainedGamesManager::clear() {
	_chainedGames.clear();
}

void ChainedGamesManager::push(const Common::String target, const int slot) {
	Game game;
	game.target = target;
	game.slot = slot;
	_chainedGames.push(game);
}

bool ChainedGamesManager::pop(Common::String &target, int &slot) {
	if (_chainedGames.empty()) {
		return false;
	}
	Game game = _chainedGames.pop();
	target = game.target;
	slot = game.slot;
	return true;
}

namespace Common {
DECLARE_SINGLETON(ChainedGamesManager);
}

Engine::Engine(OSystem *syst)
	: _system(syst),
		_mixer(_system->getMixer()),
		_timer(_system->getTimerManager()),
		_eventMan(_system->getEventManager()),
		_saveFileMan(_system->getSavefileManager()),
		_targetName(ConfMan.getActiveDomainName()),
		_metaEngine(nullptr),
		_pauseLevel(0),
		_pauseStartTime(0),
		_saveSlotToLoad(-1),
		_autoSaving(false),
		_engineStartTime(_system->getMillis()),
		_mainMenuDialog(NULL),
		_debugger(NULL),
		_autosaveInterval(ConfMan.getInt("autosave_period")),
		_lastAutosaveTime(_system->getMillis()) {

	g_engine = this;
	_quitRequested = false;
	Common::setErrorOutputFormatter(defaultOutputFormatter);
	Common::setErrorHandler(defaultErrorHandler);

	// FIXME: Get rid of the following again. It is only here
	// temporarily. We really should never run with a non-working Mixer,
	// so ought to handle this at a much earlier stage. If we *really*
	// want to support systems without a working mixer, then we need
	// more work. E.g. we could modify the Mixer to immediately drop any
	// streams passed to it. This way, at least we don't crash because
	// heaps of (sound) memory get allocated but never freed. Of course,
	// there still would be problems with many games...
	if (!_mixer->isReady())
		warning("Sound initialization failed. This may cause severe problems in some games");

	// Setup a dummy cursor and palette, so that all engines can use
	// CursorMan.replace without having any headaches about memory leaks.
	//
	// If an engine only used CursorMan.replaceCursor and no cursor has
	// been setup before, then replaceCursor just uses pushCursor. This
	// means that the engine's cursor is never again removed from
	// CursorMan. Hence we setup a fake cursor here and remove it again
	// in the destructor.
	CursorMan.pushCursor(NULL, 0, 0, 0, 0, 0);
	// Note: Using this dummy palette will actually disable cursor
	// palettes till the user enables it again.
	CursorMan.pushCursorPalette(NULL, 0, 0);

	// If we go from engine A to engine B via launcher, the palette
	// is not touched during this process, since our GUI is 16-bit
	// or 32-bit.
	//
	// This may lead to residual palette entries held in the backend
	// from a previous engine. Here we make sure we reset the palette.
	byte dummyPalette[768];
	memset(dummyPalette, 0, 768);
	g_system->getPaletteManager()->setPalette(dummyPalette, 0, 256);

	defaultSyncSoundSettings();

	// Register original bug fixes as defaults...
	ConfMan.registerDefault("enhancements", kEnhGameBreakingBugFixes | kEnhGrp1);
	if (!ConfMan.hasKey("enhancements", _targetName)) {
		if (ConfMan.hasKey("enable_enhancements", _targetName) && ConfMan.getBool("enable_enhancements", _targetName)) {
			// Was the "enable_enhancements" key previously set to true?
			// Convert it to a full activation of the enhancement flags then!
			ConfMan.setInt("enhancements", kEnhGameBreakingBugFixes | kEnhGrp1 | kEnhGrp2 | kEnhGrp3 | kEnhGrp4);
		}
	}

	_activeEnhancements = (int32)ConfMan.getInt("enhancements");
}

Engine::~Engine() {
	_mixer->stopAll();

	// Flush any pending remaining events
	Common::Event evt;
	while (g_system->getEventManager()->pollEvent(evt)) {}

	delete _debugger;
	delete _mainMenuDialog;
	g_engine = NULL;

	// Remove our cursors again to prevent memory leaks
	CursorMan.popCursor();
	CursorMan.popCursorPalette();
}

void Engine::initializePath(const Common::FSNode &gamePath) {
	SearchMan.addDirectory(gamePath, 0, 4);
}

bool Engine::enhancementEnabled(int32 cls) {
	return _activeEnhancements & cls;
}

void initCommonGFX(bool is3D) {
	const Common::ConfigManager::Domain *gameDomain = ConfMan.getActiveDomain();

	// Any global or command line settings already have been applied at the time
	// we get here, so we only do something if the game domain overrides those
	// values
	if (!gameDomain)
		return;

	if (gameDomain->contains("aspect_ratio"))
		g_system->setFeatureState(OSystem::kFeatureAspectRatioCorrection, ConfMan.getBool("aspect_ratio"));

	if (gameDomain->contains("fullscreen"))
		g_system->setFeatureState(OSystem::kFeatureFullscreenMode, ConfMan.getBool("fullscreen"));

	if (gameDomain->contains("vsync"))
		g_system->setFeatureState(OSystem::kFeatureVSync, ConfMan.getBool("vsync"));

	if (gameDomain->contains("stretch_mode"))
		g_system->setStretchMode(ConfMan.get("stretch_mode").c_str());

	// Stop here for hardware-accelerated 3D games
	if (is3D)
		return;

	// Set up filtering, scaling and shaders for 2D games
	if (gameDomain->contains("filtering"))
		g_system->setFeatureState(OSystem::kFeatureFilteringMode, ConfMan.getBool("filtering"));

	if (gameDomain->contains("scaler") || gameDomain->contains("scale_factor"))
		g_system->setScaler(ConfMan.get("scaler").c_str(), ConfMan.getInt("scale_factor"));

	if (gameDomain->contains("shader"))
		g_system->setShader(ConfMan.getPath("shader"));

	// TODO: switching between OpenGL and SurfaceSDL is quite fragile
	// and the SDL backend doesn't really need this so leave it out
	// for now to avoid regressions
#ifndef SDL_BACKEND
	if (gameDomain->contains("gfx_mode"))
		g_system->setGraphicsMode(ConfMan.get("gfx_mode").c_str());
#endif
}

// Please leave the splash screen in working order for your releases, even if they're commercial.
// This is a proper and good way to show your appreciation for our hard work over these years.
bool splash = false;

#include "logo_data.h"

void splashScreen() {
	Common::MemoryReadStream stream(logo_data, ARRAYSIZE(logo_data));

	Image::BitmapDecoder bitmap;

	if (!bitmap.loadStream(stream)) {
		warning("Error loading logo file");
		return;
	}

	g_system->showOverlay();
	float scaleFactor = g_system->getHiDPIScreenFactor();
	int16 overlayWidth = g_system->getOverlayWidth();
	int16 overlayHeight = g_system->getOverlayHeight();
	int16 scaledW = (int16)(overlayWidth / scaleFactor);
	int16 scaledH = (int16)(overlayHeight / scaleFactor);

	// Fill with orange
	Graphics::Surface screen;
	screen.create(scaledW, scaledH, g_system->getOverlayFormat());
	screen.fillRect(Common::Rect(screen.w, screen.h), screen.format.ARGBToColor(0xff, 0xcc, 0x66, 0x00));

	// Print version information
	const Graphics::Font *font = FontMan.getFontByUsage(Graphics::FontManager::kConsoleFont);
	int w = font->getStringWidth(gScummVMVersionDate);
	int x = screen.w - w - 5;
	int y = screen.h - font->getFontHeight() - 5;
	font->drawString(&screen, gScummVMVersionDate, x, y, w, screen.format.ARGBToColor(0xff, 0, 0, 0));

	// Scale if needed and copy to overlay
	if (screen.w != overlayWidth) {
		Graphics::Surface *scaledScreen = screen.scale(overlayWidth, overlayHeight, false);
		g_system->copyRectToOverlay(scaledScreen->getPixels(), scaledScreen->pitch, 0, 0, scaledScreen->w, scaledScreen->h);
		scaledScreen->free();
		delete scaledScreen;
	} else
		g_system->copyRectToOverlay(screen.getPixels(), screen.pitch, 0, 0, screen.w, screen.h);
	screen.free();

	// Draw logo
	Graphics::Surface *logo = bitmap.getSurface()->convertTo(g_system->getOverlayFormat(), bitmap.getPalette());
	if (scaleFactor != 1.0f) {
		Graphics::Surface *tmp = logo->scale(int16(logo->w * scaleFactor), int16(logo->h * scaleFactor), true);
		logo->free();
		delete logo;
		logo = tmp;
	}

	int lx = MAX((overlayWidth - logo->w) / 2, 0);
	int ly = MAX((overlayHeight - logo->h) / 2, 0);
	int lw = MIN<uint16>(logo->w, overlayWidth - lx);
	int lh = MIN<uint16>(logo->h, overlayHeight - ly);

	g_system->copyRectToOverlay(logo->getPixels(), logo->pitch, lx, ly, lw, lh);
	logo->free();
	delete logo;

	g_system->updateScreen();

	// Delay 0.6 secs
	uint time0 = g_system->getMillis();
	Common::Event event;

	// We must poll an event in order to have the window shown at least on Mac
	g_system->getEventManager()->pollEvent(event);

	while (time0 + 600 > g_system->getMillis()) {
		g_system->delayMillis(10);
	}
	g_system->hideOverlay();

	splash = true;
}

void initGraphicsModes(const Graphics::ModeList &modes) {
	g_system->initSizeHint(modes);
}

/**
 * Inits any of the modes in "modes". "modes" is in the order of preference.
 * Return value is index in modes of resulting mode.
 */
int initGraphicsAny(const Graphics::ModeWithFormatList &modes, int start) {
	int candidate = -1;
	OSystem::TransactionError gfxError = OSystem::kTransactionSizeChangeFailed;
	int last_width = 0, last_height = 0;

	for (candidate = start; candidate < (int)modes.size(); candidate++) {
		g_system->beginGFXTransaction();
		initCommonGFX(false);
#ifdef USE_RGB_COLOR
		if (modes[candidate].hasFormat)
			g_system->initSize(modes[candidate].width, modes[candidate].height, &modes[candidate].format);
		else {
			Graphics::PixelFormat bestFormat = g_system->getSupportedFormats().front();
			g_system->initSize(modes[candidate].width, modes[candidate].height, &bestFormat);
		}
#else
		g_system->initSize(modes[candidate].width, modes[candidate].height);
#endif
		last_width = modes[candidate].width;
		last_height = modes[candidate].height;

		gfxError = g_system->endGFXTransaction();

		if (!splash && !GUI::GuiManager::instance()._launched)
			splashScreen();

		if (gfxError == OSystem::kTransactionSuccess)
			return candidate;

		// If error is related to resolution, continue
		if (gfxError & (OSystem::kTransactionSizeChangeFailed | OSystem::kTransactionFormatNotSupported))
			continue;

		break;
	}

	// Error out on size switch failure
	if (gfxError & OSystem::kTransactionSizeChangeFailed) {
		Common::U32String message;
		message = Common::U32String::format(_("Could not switch to resolution '%dx%d'."), last_width, last_height);

		GUIErrorMessage(message);
		error("Could not switch to resolution '%dx%d'.", last_width, last_height);
	}

	// Just show warnings then these occur:
#ifdef USE_RGB_COLOR
	if (gfxError & OSystem::kTransactionFormatNotSupported) {
		Common::U32String message = _("Could not initialize color format.");

		GUI::MessageDialog dialog(message);
		dialog.runModal();
	}
#endif

	if (gfxError & OSystem::kTransactionModeSwitchFailed) {
		Common::U32String message;
		message = Common::U32String::format(_("Could not switch to video mode '%s'."), ConfMan.get("gfx_mode").c_str());

		GUI::MessageDialog dialog(message);
		dialog.runModal();
	}

	if (gfxError & OSystem::kTransactionStretchModeSwitchFailed) {
		Common::U32String message;
		message = Common::U32String::format(_("Could not switch to stretch mode '%s'."), ConfMan.get("stretch_mode").c_str());

		GUI::MessageDialog dialog(message);
		dialog.runModal();
	}

	if (gfxError & OSystem::kTransactionAspectRatioFailed) {
		GUI::MessageDialog dialog(_("Could not apply aspect ratio setting."));
		dialog.runModal();
	}

	if (gfxError & OSystem::kTransactionFullscreenFailed) {
		GUI::MessageDialog dialog(_("Could not apply fullscreen setting."));
		dialog.runModal();
	}

	if (gfxError & OSystem::kTransactionFilteringFailed) {
		GUI::MessageDialog dialog(_("Could not apply filtering setting."));
		dialog.runModal();
	}

	return candidate;
}

void initGraphics(int width, int height, const Graphics::PixelFormat *format) {
	Graphics::ModeWithFormatList modes;
	modes.push_back(Graphics::ModeWithFormat(width, height, format));
	initGraphicsAny(modes);
}

/**
 * Determines the first matching format between two lists.
 *
 * @param backend	The higher priority list, meant to be a list of formats supported by the backend
 * @param frontend	The lower priority list, meant to be a list of formats supported by the engine
 * @return			The first item on the backend list that also occurs on the frontend list
 *					or PixelFormat::createFormatCLUT8() if no matching formats were found.
 */
inline Graphics::PixelFormat findCompatibleFormat(const Common::List<Graphics::PixelFormat> &backend, const Common::List<Graphics::PixelFormat> &frontend) {
#ifdef USE_RGB_COLOR
	for (const auto &back : backend) {
		for (auto &front : frontend) {
			if (back == front)
				return back;
		}
	}
#endif
	return Graphics::PixelFormat::createFormatCLUT8();
}


void initGraphics(int width, int height, const Common::List<Graphics::PixelFormat> &formatList) {
	Graphics::PixelFormat format = findCompatibleFormat(g_system->getSupportedFormats(), formatList);
	initGraphics(width, height, &format);
}

void initGraphics(int width, int height) {
	Graphics::PixelFormat format = Graphics::PixelFormat::createFormatCLUT8();
	initGraphics(width, height, &format);
}

void initGraphics3d(int width, int height) {
	g_system->beginGFXTransaction();
		g_system->setGraphicsMode(0, OSystem::kGfxModeRender3d);
		initCommonGFX(true);
		g_system->initSize(width, height);
	g_system->endGFXTransaction();

	if (!splash && !GUI::GuiManager::instance()._launched) {
		Common::Event event;
		(void)g_system->getEventManager()->pollEvent(event);
		splashScreen();
	}
}

void GUIErrorMessageWithURL(const Common::U32String &msg, const char *url) {
	GUIErrorMessage(msg, url);
}

void GUIErrorMessageWithURL(const Common::String &msg, const char *url) {
	GUIErrorMessage(Common::U32String(msg), url);
}

void GUIErrorMessage(const Common::String &msg, const char *url) {
	GUIErrorMessage(Common::U32String(msg), url);
}

void GUIErrorMessage(const Common::U32String &msg, const char *url) {
	g_system->setWindowCaption(_("Error"));
	g_system->beginGFXTransaction();
		initCommonGFX(false);
		g_system->initSize(320, 200);
	if (g_system->endGFXTransaction() == OSystem::kTransactionSuccess) {
		if (url) {
			GUI::MessageDialogWithURL dialog(msg, url);
			dialog.runModal();
		} else {
			GUI::MessageDialog dialog(msg);
			dialog.runModal();
		}
	} else {
		error("%s", msg.encode().c_str());
	}
}

void GUIErrorMessageFormat(const char *fmt, ...) {
	Common::String msg;

	va_list va;
	va_start(va, fmt);
	msg = Common::String::vformat(fmt, va);
	va_end(va);

	GUIErrorMessage(msg);
}

void GUIErrorMessageFormatU32StringPtr(const Common::U32String *fmt, ...) {
	Common::U32String msg;

	va_list va;
	va_start(va, fmt);
	Common::U32String::vformat(fmt->begin(), fmt->end(), msg, va);
	va_end(va);

	GUIErrorMessage(msg);
}

/**
 * Checks if supported (extracted) audio files are found.
 *
 * @return			true if audio files of the expected naming scheme are found, as long as ScummVM
 *					is also built with support to the respective audio format (eg. ogg, flac, mad/mp3)
 */
bool Engine::existExtractedCDAudioFiles(uint track) {
	return g_system->getAudioCDManager()->existExtractedCDAudioFiles(track);
}

/**
 * Displays a warning on Windows version of ScummVM, if game data
 * are read from the same CD drive which should also play game CD audio.
 * @return			true, if this case is applicable and the warning is displayed
 */
bool Engine::isDataAndCDAudioReadFromSameCD() {
	// If we can find a compressed audio track, then it should be ok even
	// if it's running from CD.
	if (existExtractedCDAudioFiles()) {
		return false;
	}

	if (g_system->getAudioCDManager()->isDataAndCDAudioReadFromSameCD()) {
		GUI::MessageDialog dialog(
			_("You appear to be playing this game directly\n"
			"from the CD. This is known to cause problems,\n"
			"and it is therefore recommended that you copy\n"
			"the data files to your hard disk instead.\n"
			"See the documentation (CD audio) for details."), _("OK"));
		dialog.runModal();
		return true;
	}
	return false;
}

/**
 * Displays a warning, for the case when the game has CD audio but
 * no extracted (ripped) audio files were found.
 *
 * This method only shows the warning. It does not check for the
 * existence of the ripped audio files.
 */
void Engine::warnMissingExtractedCDAudio() {
	// Display a modal informative dialogue for the case when:
	// - The game has audio tracks,
	// - and the tracks have not been ripped.
	GUI::MessageDialog dialog(
		_("This game has audio tracks on its CD. These\n"
		"tracks need to be ripped from the CD using\n"
		"an appropriate CD audio extracting tool in\n"
		"order to listen to the game's music.\n"
		"See the documentation (CD audio) for details."), _("OK"));
	dialog.runModal();
}

void Engine::handleAutoSave() {
#ifdef ENABLE_EVENTRECORDER
	if (!g_eventRec.processAutosave())
		return;
#endif
	const int diff = _system->getMillis() - _lastAutosaveTime;

	if (_autosaveInterval != 0 && diff > (_autosaveInterval * 1000)) {
		// Save the autosave
		saveAutosaveIfEnabled();
	}
}

bool Engine::warnBeforeOverwritingAutosave() {
	SaveStateDescriptor desc = getMetaEngine()->querySaveMetaInfos(
		_targetName.c_str(), getAutosaveSlot());
	if (!desc.isValid() || desc.isAutosave())
		return true;
	Common::U32StringArray altButtons;
	altButtons.push_back(_("Delete"));
	altButtons.push_back(_("Skip autosave"));
	const Common::U32String message = Common::U32String::format(
				_("WARNING: The autosave slot contains a saved game named %S, and an autosave is pending.\n"
				  "Please move this saved game to a new slot, or delete it if it's no longer needed.\n"
				  "Alternatively, you can skip the autosave (will prompt again in 5 minutes)."), desc.getDescription().c_str());
	GUI::MessageDialog warn(message, _("Move"), altButtons);
	switch (runDialog(warn)) {
	case GUI::kMessageOK:
		if (getMetaEngine()->copySaveFileToFreeSlot(_targetName.c_str(), getAutosaveSlot())) {
				g_system->getSavefileManager()->removeSavefile(
							getMetaEngine()->getSavegameFile(getAutosaveSlot(), _targetName.c_str()));
		} else {
				GUI::MessageDialog error(_("ERROR: Could not copy the savegame to a new slot"));
				error.runModal();
				return false;
		}
		return true;
	case GUI::kMessageAlt: // Delete
		g_system->getSavefileManager()->removeSavefile(
					getMetaEngine()->getSavegameFile(getAutosaveSlot(), _targetName.c_str()));
		return true;
	case GUI::kMessageAlt + 1: // Skip autosave
		return false;
	default: // Hitting Escape returns -1. On this case, don't save but do prompt again later.
		return false;
	}
}

void Engine::saveAutosaveIfEnabled() {
	// Prevents recursive calls if saving the game causes the engine to poll events
	// (as is the case with the AGS engine for example, or when showing a prompt).
	if (_autoSaving || _autosaveInterval == 0)
		return;
	const int autoSaveSlot = getAutosaveSlot();
	if (autoSaveSlot < 0)
		return;
	_autoSaving = true;

	bool saveFlag = canSaveAutosaveCurrently();
	const Common::String autoSaveName = Common::convertFromU32String(_("Autosave"));

	// First check for an existing savegame in the slot, and if present, if it's an autosave
	if (saveFlag)
		saveFlag = warnBeforeOverwritingAutosave();

	if (saveFlag && saveGameState(autoSaveSlot, autoSaveName, true).getCode() != Common::kNoError) {
		// Couldn't autosave at the designated time
		g_system->displayMessageOnOSD(_("Error occurred making autosave"));
		saveFlag = false;
	}

	_lastAutosaveTime = _system->getMillis();

	if (!saveFlag) {
		// Set the next autosave interval to be in 5 minutes, rather than whatever
		// full autosave interval the user has selected
		_lastAutosaveTime += ((5 * 60 - _autosaveInterval) * 1000);
	}
	_autoSaving = false;
}

void Engine::errorString(const char *buf1, char *buf2, int size) {
	Common::strlcpy(buf2, buf1, size);
}

PauseToken Engine::pauseEngine() {
	assert(_pauseLevel >= 0);

	_pauseLevel++;

	if (_pauseLevel == 1) {
		_pauseStartTime = _system->getMillis();
		pauseEngineIntern(true);
	}

	return PauseToken(this);
}

void Engine::resumeEngine() {
	assert(_pauseLevel > 0);

	_pauseLevel--;

	if (_pauseLevel == 0) {
		pauseEngineIntern(false);
		_engineStartTime += _system->getMillis() - _pauseStartTime;
		_pauseStartTime = 0;
	}
}

void Engine::pauseEngineIntern(bool pause) {
	// By default, just (un)pause all digital sounds
	_mixer->pauseAll(pause);
}

void Engine::openMainMenuDialog() {
	if (!_mainMenuDialog)
		_mainMenuDialog = new MainMenuDialog(this);
	Common::TextToSpeechManager *ttsMan = g_system->getTextToSpeechManager();
	if (ttsMan != nullptr) {
		ttsMan->pushState();
		g_gui.initTextToSpeech();
	}

	setGameToLoadSlot(-1);

	bool hasVKeyb = g_system->getFeatureState(OSystem::kFeatureVirtualKeyboard);
	if (hasVKeyb)
		g_system->setFeatureState(OSystem::kFeatureVirtualKeyboard, false);

	runDialog(*_mainMenuDialog);

	if (hasVKeyb)
		g_system->setFeatureState(OSystem::kFeatureVirtualKeyboard, true);

	// Load savegame after main menu execution
	// (not from inside the menu loop to avoid
	// mouse cursor glitches and similar bugs,
	// e.g. #4420).
	if (_saveSlotToLoad >= 0) {
		Common::Error status = loadGameState(_saveSlotToLoad);
		if (status.getCode() != Common::kNoError) {
			Common::U32String failMessage = Common::U32String::format(_("Failed to load saved game (%s)! "
				  "Please consult the README for basic information, and for "
				  "instructions on how to obtain further assistance."), status.getDesc().c_str());
			GUI::MessageDialog dialog(failMessage);
			dialog.runModal();
		}
	}

	if (ttsMan != nullptr)
		ttsMan->popState();

	g_system->applyBackendSettings();
	applyGameSettings();
	syncSoundSettings();
}

bool Engine::warnUserAboutUnsupportedGame(Common::String msg) {
	if (ConfMan.getBool("enable_unsupported_game_warning")) {
		Common::TextToSpeechManager *ttsMan = g_system->getTextToSpeechManager();
		if (ttsMan != nullptr) {
			ttsMan->pushState();
			g_gui.initTextToSpeech();
		}

		GUI::MessageDialog alert(!msg.empty() ? _("WARNING: ") + Common::U32String(msg) + _(" Shall we still run the game?") :
				 _("WARNING: The game you are about to start is"
			" not yet fully supported by ScummVM. As such, it is likely to be"
			" unstable, and any saved game you make might not work in future"
			" versions of ScummVM."), _("Start anyway"), _("Cancel"));
		int status = alert.runModal();

		if (ttsMan != nullptr)
			ttsMan->popState();

		return status == GUI::kMessageOK;
	}
	return true;
}

void Engine::errorUnsupportedGame(Common::String extraMsg) {
	Common::TextToSpeechManager *ttsMan = g_system->getTextToSpeechManager();
	if (ttsMan != nullptr) {
		ttsMan->pushState();
		g_gui.initTextToSpeech();
	}

	Common::String message = extraMsg.empty() ? _("This game is not supported.") : _("This game is not supported for the following reason:\n\n");
	message += _(extraMsg);
	message += "\n\n";
	GUI::MessageDialog(message).runModal();

	if (ttsMan != nullptr)
		ttsMan->popState();
}

uint32 Engine::getTotalPlayTime() const {
	if (!_pauseLevel)
		return _system->getMillis() - _engineStartTime;
	else
		return _pauseStartTime - _engineStartTime;
}

void Engine::setTotalPlayTime(uint32 time) {
	const uint32 currentTime = _system->getMillis();

	// We need to reset the pause start time here in case the engine is already
	// paused to avoid any incorrect play time counting.
	if (_pauseLevel > 0)
		_pauseStartTime = currentTime;

	_engineStartTime = currentTime - time;
}

int Engine::runDialog(GUI::Dialog &dialog) {
	PauseToken pt = pauseEngine();
	int result = dialog.runModal();

	return result;
}

void Engine::setGameToLoadSlot(int slot) {
	_saveSlotToLoad = slot;
}

void Engine::syncSoundSettings() {
	defaultSyncSoundSettings();
}

void Engine::defaultSyncSoundSettings() {
	// Sync the engine with the config manager
	int soundVolumeMusic = ConfMan.getInt("music_volume");
	int soundVolumeSFX = ConfMan.getInt("sfx_volume");
	int soundVolumeSpeech = ConfMan.getInt("speech_volume");

	bool mute = false;
	if (ConfMan.hasKey("mute"))
		mute = ConfMan.getBool("mute");

	// We need to handle the speech mute separately here. This is because the
	// engine code should be able to rely on all speech sounds muted when the
	// user specified subtitles only mode, which results in "speech_mute" to
	// be set to "true". The global mute setting has precedence over the
	// speech mute setting though.
	bool speechMute = mute;
	if (!speechMute)
		speechMute = ConfMan.getBool("speech_mute");

	_mixer->muteSoundType(Audio::Mixer::kPlainSoundType, mute);
	_mixer->muteSoundType(Audio::Mixer::kMusicSoundType, mute);
	_mixer->muteSoundType(Audio::Mixer::kSFXSoundType, mute);
	_mixer->muteSoundType(Audio::Mixer::kSpeechSoundType, speechMute);

	_mixer->setVolumeForSoundType(Audio::Mixer::kPlainSoundType, Audio::Mixer::kMaxMixerVolume);
	_mixer->setVolumeForSoundType(Audio::Mixer::kMusicSoundType, soundVolumeMusic);
	_mixer->setVolumeForSoundType(Audio::Mixer::kSFXSoundType, soundVolumeSFX);
	_mixer->setVolumeForSoundType(Audio::Mixer::kSpeechSoundType, soundVolumeSpeech);
}

void Engine::flipMute() {
	// Mute will be set to true by default here. This has two reasons:
	// - if the game already has an "mute" config entry, it will be overwritten anyway.
	// - if it does not have a "mute" config entry, the sound is unmuted currently and should be muted now.
	bool mute = true;

	if (ConfMan.hasKey("mute")) {
		mute = !ConfMan.getBool("mute");
	}

	ConfMan.setBool("mute", mute);

	syncSoundSettings();
}

Common::Error Engine::loadGameState(int slot) {
	// In case autosaves are on, do a save first before loading the new save
	saveAutosaveIfEnabled();

	Common::InSaveFile *saveFile = _saveFileMan->openForLoading(getSaveStateName(slot));

	if (!saveFile)
		return Common::kReadingFailed;

	Common::Error result = loadGameStream(saveFile);
	if (result.getCode() == Common::kNoError) {
		ExtendedSavegameHeader header;
		if (MetaEngine::readSavegameHeader(saveFile, &header))
			setTotalPlayTime(header.playtime);
	}

	delete saveFile;
	return result;
}

Common::Error Engine::loadGameStream(Common::SeekableReadStream *stream) {
	// Default to returning an error when not implemented
	return Common::kReadingFailed;
}

bool Engine::canLoadGameStateCurrently(Common::U32String *msg) {
	// Do not allow loading by default
	return false;
}

Common::Error Engine::saveGameState(int slot, const Common::String &desc, bool isAutosave) {
	Common::OutSaveFile *saveFile = _saveFileMan->openForSaving(getSaveStateName(slot));

	if (!saveFile)
		return Common::kWritingFailed;

	Common::Error result = saveGameStream(saveFile, isAutosave);
	if (result.getCode() == Common::kNoError) {
		getMetaEngine()->appendExtendedSave(saveFile, getTotalPlayTime(), desc, isAutosave);

		saveFile->finalize();
	}

	delete saveFile;
	return result;
}

Common::Error Engine::saveGameStream(Common::WriteStream *stream, bool isAutosave) {
	// Default to returning an error when not implemented
	return Common::kWritingFailed;
}

bool Engine::canSaveGameStateCurrently(Common::U32String *msg) {
	// Do not allow saving by default
	return false;
}

bool Engine::loadGameDialog() {
	if (!canLoadGameStateCurrently()) {
		g_system->displayMessageOnOSD(_("Loading game is currently unavailable"));
		return false;
	}

	GUI::SaveLoadChooser *dialog = new GUI::SaveLoadChooser(_("Load game:"), _("Load"), false);

	int slotNum;
	{
		PauseToken pt = pauseEngine();
		slotNum = dialog->runModalWithCurrentTarget();
	}

	delete dialog;

	if (slotNum < 0)
		return false;

	Common::Error loadError = loadGameState(slotNum);
	if (loadError.getCode() != Common::kNoError) {
		GUI::MessageDialog errorDialog(loadError.getDesc());
		errorDialog.runModal();
		return false;
	}

	return true;
}

bool Engine::saveGameDialog() {
	if (!canSaveGameStateCurrently()) {
		g_system->displayMessageOnOSD(_("Saving game is currently unavailable"));
		return false;
	}

	GUI::SaveLoadChooser *dialog = new GUI::SaveLoadChooser(_("Save game:"), _("Save"), true);
	int slotNum;
	{
		PauseToken pt = pauseEngine();
		slotNum = dialog->runModalWithCurrentTarget();
	}

	Common::String desc = dialog->getResultString();
	if (desc.empty())
		desc = dialog->createDefaultSaveDescription(slotNum);

	delete dialog;

	if (slotNum < 0)
		return false;

	Common::Error saveError = saveGameState(slotNum, desc);
	if (saveError.getCode() != Common::kNoError) {
		GUI::MessageDialog errorDialog(saveError.getDesc());
		errorDialog.runModal();
		return false;
	}

	return true;
}

void Engine::quitGame() {
	Common::Event event;

	event.type = Common::EVENT_QUIT;
	g_system->getEventManager()->pushEvent(event);
	_quitRequested = true;
}

bool Engine::shouldQuit() {
	Common::EventManager *eventMan = g_system->getEventManager();
	return eventMan->shouldQuit() || eventMan->shouldReturnToLauncher()
		|| _quitRequested;
}

GUI::Debugger *Engine::getOrCreateDebugger() {
	if (!_debugger)
		// Create a bare-bones debugger. This is useful for engines without their own
		// debugger when an error occurs
		_debugger = new GUI::Debugger();

	return _debugger;
}

PauseToken::PauseToken() : _engine(nullptr) {}

PauseToken::PauseToken(Engine *engine) : _engine(engine) {}

void PauseToken::operator=(const PauseToken &t2) {
	if (_engine) {
		error("Tried to assign to an already busy PauseToken");
	}
	_engine = t2._engine;
	if (_engine) {
		_engine->_pauseLevel++;
	}
}

PauseToken::PauseToken(const PauseToken &t2) : _engine(t2._engine) {
	if (_engine) {
		_engine->_pauseLevel++;
	}
}

void PauseToken::clear() {
	if (!_engine) {
		error("Tried to clear an already cleared PauseToken");
	}
	_engine->resumeEngine();
	_engine = nullptr;
}

PauseToken::~PauseToken() {
	if (_engine) {
		_engine->resumeEngine();
	}
}

#if __cplusplus >= 201103L
PauseToken::PauseToken(PauseToken &&t2) : _engine(t2._engine) {
	t2._engine = nullptr;
}

void PauseToken::operator=(PauseToken &&t2) {
	if (_engine) {
		error("Tried to assign to an already busy PauseToken");
	}
	_engine = t2._engine;
	t2._engine = nullptr;
}
#endif
