//  SPDX-License-Identifier: MIT
//
//  ES-DE is a frontend for browsing and launching games from your multi-platform game collection.
//
//  The column limit is 100 characters.
//  All ES-DE C++ source code is formatted using clang-format.
//
//  main.cpp
//
//  Main program loop. Interprets command-line arguments, checks for the home folder
//  and es_settings.xml configuration file, sets up the application environment and
//  starts listening to SDL events.
//

#include "ApplicationUpdater.h"
#include "ApplicationVersion.h"
#include "AudioManager.h"
#include "CollectionSystemsManager.h"
#include "InputManager.h"
#include "Log.h"
#include "MameNames.h"
#include "MediaViewer.h"
#include "PDFViewer.h"
#include "Screensaver.h"
#include "Scripting.h"
#include "Settings.h"
#include "Sound.h"
#include "SystemData.h"
#include "guis/GuiDetectDevice.h"
#include "guis/GuiLaunchScreen.h"
#include "utils/FileSystemUtil.h"
#include "utils/PlatformUtil.h"
#include "utils/StringUtil.h"
#include "views/ViewController.h"

#include <SDL2/SDL_events.h>
#include <SDL2/SDL_main.h>
#include <SDL2/SDL_timer.h>

#if defined(__ANDROID__)
#include "utils/PlatformUtilAndroid.h"
#endif

#if defined(__EMSCRIPTEN__)
#include <emscripten.h>
#endif

#if defined(_WIN64)
#include <cstring>
#include <windows.h>
#endif

#include <FreeImage.h>
#include <fstream>
#include <iostream>
#include <time.h>

namespace
{
    SDL_Event event {};
    Renderer* renderer {nullptr};
    Window* window {nullptr};
    int lastTime {0};

#if defined(APPLICATION_UPDATER)
    bool noUpdateCheck {false};
#endif
    bool forceInputConfig {false};
    bool createSystemDirectories {false};
    bool settingsNeedSaving {false};
    bool portableMode {false};

    enum loadSystemsReturnCode {
        LOADING_OK,
        INVALID_FILE,
        NO_ROMS
    };

#if defined(_WIN64)
    enum win64ConsoleType {
        NO_CONSOLE,
        PARENT_CONSOLE,
        ALLOCATED_CONSOLE
    };
#endif

} // namespace

#if defined(_WIN64)
// As we link using the WINDOWS subsystem there is no console allocated on application startup.
// As such we'll attempt to attach to a parent console, and if this fails it probably means we've
// not been started from the command line. In this case there is no need to redirect anything.
// Note that some console types such as the "Git Bash" shell simply don't work properly. Windows
// thinks it's attaching to a console but is unable to redirect the standard input and output.
// Output also can't be redirected or piped by the user for any console type, and PowerShell
// behaves quite strange. Still it works well enough to be somewhat usable.
void outputToConsole()
{
    HANDLE outputHandle {nullptr};
    HWND consoleWindow {nullptr};

    // Try to attach to a parent console process.
    if (AttachConsole(ATTACH_PARENT_PROCESS))
        outputHandle = GetStdHandle(STD_OUTPUT_HANDLE);

    // If there is a parent console process, then attempt to retrieve its handle.
    if (outputHandle != INVALID_HANDLE_VALUE && outputHandle != nullptr)
        consoleWindow = GetConsoleWindow();

    // If we couldn't retrieve the handle, then we're probably not running from a console.
    if (!consoleWindow)
        return;

    // Redirect stdin, stdout and stderr to the console window.
    FILE* fp {nullptr};
    freopen_s(&fp, "CONIN$", "r", stdin);
    freopen_s(&fp, "CONOUT$", "w", stdout);
    setvbuf(stdout, 0, _IONBF, 0);
    freopen_s(&fp, "CONOUT$", "w", stderr);
    setvbuf(stderr, 0, _IONBF, 0);

    // Point the standard streams to the console.
    std::ios::sync_with_stdio(true);

    // Clear the error state for each standard stream.
    std::wcout.clear();
    std::cout.clear();
    std::wcerr.clear();
    std::cerr.clear();
    std::wcin.clear();
    std::cin.clear();
}
#endif

bool parseArguments(const std::vector<std::string>& arguments)
{
    Utils::FileSystem::setExePath(arguments[0]);
    const std::string portableFilePath {Utils::FileSystem::getExePath() + "/portable.txt"};

    // This is primarily intended for portable ES-DE installations on Windows (for example
    // placed on a USB memory stick) but it may be usable for other operating systems too.
    if (Utils::FileSystem::exists(portableFilePath)) {
        std::cout << "Found portable.txt in the ES-DE executable directory\n";
        std::ifstream portableFile;
        std::string homePath;
#if defined(_WIN64)
        portableFile.open(Utils::String::stringToWideString(portableFilePath).c_str());
#else
        portableFile.open(portableFilePath.c_str());
#endif
        if (!portableFile.fail()) {
            std::string relativePath;
            getline(portableFile, relativePath);
            // If the file is empty, use the ES-DE executable directory as home.
            if (relativePath == "")
                homePath = Utils::FileSystem::getExePath();
            else
                homePath = Utils::FileSystem::getExePath() + "/" + relativePath;

#if defined(_WIN64)
            homePath = Utils::String::replace(homePath, "/", "\\");
#endif
            bool homeExists {false};

            if (Utils::FileSystem::exists(homePath))
                homeExists = true;
#if defined(_WIN64)
            else if (homePath.size() == 2 && Utils::FileSystem::driveExists(homePath))
                homeExists = true;
#endif
            if (!homeExists) {
                std::cerr << "Error: Defined home path \"" << homePath << "\" does not exist\n";
            }
            else if (Utils::FileSystem::isRegularFile(homePath)) {
                std::cerr << "Error: Defined home path \"" << homePath << "\" is a file\n";
            }
            else {
                std::cout << "Setting home path to \"" << homePath << "\"\n";
                Utils::FileSystem::setHomePath(homePath);
                portableMode = true;
            }
        }
        portableFile.close();
    }

    // We need to process --home before any call to Settings::getInstance(), because
    // settings are loaded from the home path.
    for (size_t i {1}; i < arguments.size(); ++i) {
        if (arguments[i] == "--home") {
            if (i >= arguments.size() - 1) {
                std::cerr << "Error: No home path supplied with \'--home'\n";
                return false;
            }
#if defined(_WIN64)
            if (!Utils::FileSystem::exists(arguments[i + 1]) &&
                (!Utils::FileSystem::driveExists(arguments[i + 1]))) {
#else
            if (!Utils::FileSystem::exists(arguments[i + 1])) {
#endif
                std::cerr << "Error: Home path \'" << arguments[i + 1] << "\' does not exist\n";
                return false;
            }
            if (Utils::FileSystem::isRegularFile(arguments[i + 1])) {
                std::cerr << "Error: Home path \'" << arguments[i + 1]
                          << "\' is a file and not a directory\n";
                return false;
            }
            Utils::FileSystem::setHomePath(arguments[i + 1]);
            portableMode = false;
            break;
        }
    }

    for (size_t i {1}; i < arguments.size(); ++i) {
        // Skip past --home flag as we already processed it.
        if (arguments[i] == "--home") {
            ++i; // Skip the argument value.
            continue;
        }
        if (arguments[i] == "--display") {
            if (i >= arguments.size() - 1 || stoi(arguments[i + 1]) < 1 ||
                stoi(arguments[i + 1]) > 4) {
                std::cerr << "Error: Invalid display index supplied\n";
                return false;
            }
            const int displayIndex {stoi(arguments[i + 1])};
            Settings::getInstance()->setInt("DisplayIndex", displayIndex);
            settingsNeedSaving = true;
            ++i;
        }
        else if (arguments[i] == "--resolution") {
            if (i >= arguments.size() - 2) {
                std::cerr << "Error: Invalid resolution values supplied\n";
                return false;
            }
            const std::string widthArg {arguments[i + 1]};
            const std::string heightArg {arguments[i + 2]};
            if (widthArg.find_first_not_of("0123456789") != std::string::npos ||
                heightArg.find_first_not_of("0123456789") != std::string::npos) {
                std::cerr << "Error: Invalid resolution values supplied\n";
                return false;
            }
            const int width {stoi(arguments[i + 1])};
            const int height {stoi(arguments[i + 2])};
            if (width < 224 || height < 224 || width > 7680 || height > 7680 ||
                height < width / 4 || width < height / 3) {
                std::cerr << "Error: Unsupported resolution " << width << "x" << height
                          << " supplied\n";
                return false;
            }
            Settings::getInstance()->setInt("ScreenWidth", width);
            Settings::getInstance()->setInt("ScreenHeight", height);
            i += 2;
        }
        else if (arguments[i] == "--screenoffset") {
            if (i >= arguments.size() - 2) {
                std::cerr << "Error: Invalid screenoffset values supplied\n";
                return false;
            }
            const int x {stoi(arguments[i + 1])};
            const int y {stoi(arguments[i + 2])};
            Settings::getInstance()->setInt("ScreenOffsetX", x);
            Settings::getInstance()->setInt("ScreenOffsetY", y);
            i += 2;
        }
        else if (arguments[i] == "--screenrotate") {
            if (i >= arguments.size() - 1) {
                std::cerr << "Error: No screenrotate value supplied\n";
                return false;
            }
            const std::string rotateValue {arguments[i + 1]};
            if (rotateValue != "0" && rotateValue != "90" && rotateValue != "180" &&
                rotateValue != "270") {
                std::cerr << "Error: Invalid screenrotate value supplied\n";
                return false;
            }
            Settings::getInstance()->setInt("ScreenRotate", stoi(arguments[i + 1]));
            settingsNeedSaving = true;
            ++i;
        }
        else if (arguments[i] == "--fullscreen-padding") {
            if (i >= arguments.size() - 1) {
                std::cerr << "Error: No fullscreen-padding value supplied\n";
                return false;
            }
            std::string fullscreenPaddingValue {arguments[i + 1]};
            if (fullscreenPaddingValue != "on" && fullscreenPaddingValue != "off" &&
                fullscreenPaddingValue != "1" && fullscreenPaddingValue != "0") {
                std::cerr << "Error: Invalid fullscreen-padding value supplied\n";
                return false;
            }
            const bool fullscreenPadding {
                (fullscreenPaddingValue == "on" || fullscreenPaddingValue == "1") ? true : false};
            Settings::getInstance()->setBool("FullscreenPadding", fullscreenPadding);
            ++i;
        }
        else if (arguments[i] == "--vsync") {
            if (i >= arguments.size() - 1) {
                std::cerr << "Error: No VSync value supplied\n";
                return false;
            }
            std::string vSyncValue {arguments[i + 1]};
            if (vSyncValue != "on" && vSyncValue != "off" && vSyncValue != "1" &&
                vSyncValue != "0") {
                std::cerr << "Error: Invalid VSync value supplied\n";
                return false;
            }
            const bool vSync {(vSyncValue == "on" || vSyncValue == "1") ? true : false};
            Settings::getInstance()->setBool("VSync", vSync);
            ++i;
        }
        else if (arguments[i] == "--max-vram") {
            if (i >= arguments.size() - 1) {
                std::cerr << "Error: Invalid VRAM value supplied\n";
                return false;
            }
            const int maxVRAM {stoi(arguments[i + 1])};
            Settings::getInstance()->setInt("MaxVRAM", maxVRAM);
            settingsNeedSaving = true;
            ++i;
        }
#if !defined(USE_OPENGLES)
        else if (arguments[i] == "--anti-aliasing") {
            bool invalidValue {false};
            int antiAlias {0};
            if (i >= arguments.size() - 1) {
                invalidValue = true;
            }
            else {
                antiAlias = stoi(arguments[i + 1]);
                if (antiAlias != 0 && antiAlias != 2 && antiAlias != 4)
                    invalidValue = true;
            }
            if (invalidValue) {
                std::cerr << "Error: Invalid anti-aliasing value supplied\n";
                return false;
            }
            Settings::getInstance()->setInt("AntiAliasing", antiAlias);
            settingsNeedSaving = true;
            ++i;
        }
#endif
        else if (arguments[i] == "--no-splash") {
            Settings::getInstance()->setBool("SplashScreen", false);
        }
#if defined(APPLICATION_UPDATER)
        else if (arguments[i] == "--no-update-check") {
            noUpdateCheck = true;
        }
#endif
        else if (arguments[i] == "--gamelist-only") {
            Settings::getInstance()->setBool("ParseGamelistOnly", true);
            settingsNeedSaving = true;
        }
        else if (arguments[i] == "--ignore-gamelist") {
            Settings::getInstance()->setBool("IgnoreGamelist", true);
        }
        else if (arguments[i] == "--show-hidden-files") {
            Settings::getInstance()->setBool("ShowHiddenFiles", true);
            settingsNeedSaving = true;
        }
        else if (arguments[i] == "--show-hidden-games") {
            Settings::getInstance()->setBool("ShowHiddenGames", true);
            settingsNeedSaving = true;
        }
        else if (arguments[i] == "--force-full") {
            Settings::getInstance()->setString("UIMode", "full");
            Settings::getInstance()->setBool("ForceFull", true);
        }
        else if (arguments[i] == "--force-kiosk") {
            Settings::getInstance()->setBool("ForceKiosk", true);
        }
        else if (arguments[i] == "--force-kid") {
            Settings::getInstance()->setBool("ForceKid", true);
        }
        else if (arguments[i] == "--force-input-config") {
            forceInputConfig = true;
        }
        else if (arguments[i] == "--create-system-dirs") {
            createSystemDirectories = true;
        }
        else if (arguments[i] == "--debug") {
            Settings::getInstance()->setBool("Debug", true);
            Settings::getInstance()->setBool("DebugFlag", true);
            Log::setReportingLevel(LogDebug);
        }
        else if (arguments[i] == "--version" || arguments[i] == "-v") {
            std::cout << "ES-DE v" << PROGRAM_VERSION_STRING << " (r" << PROGRAM_RELEASE_NUMBER
                      << ")\n";
            return false;
        }
        else if (arguments[i] == "--help" || arguments[i] == "-h") {
            std::cout <<
                // clang-format off
"Usage: es-de [options]\n"
"ES-DE (ES-DE), Emulator Frontend\n\n"
"Options:\n"
"  --display [1 to 4]                    Display/monitor to use\n"
"  --resolution [width] [height]         Application resolution\n"
"  --screenoffset [horiz.] [vert.]       Offset screen contents within application window\n"
"  --screenrotate [0, 90, 180 or 270]    Rotate screen contents within application window\n"
"  --fullscreen-padding [1/on or 0/off]  Padding if --resolution is lower than display resolution\n"
"  --vsync [1/on or 0/off]               Turn VSync on or off (default is on)\n"
"  --max-vram [size]                     Max VRAM to use (in mebibytes) before swapping\n"
#if !defined(USE_OPENGLES)
"  --anti-aliasing [0, 2 or 4]           Set MSAA anti-aliasing to disabled, 2x or 4x\n"
#endif
"  --no-splash                           Don't show the splash screen during startup\n"
#if defined(APPLICATION_UPDATER)
"  --no-update-check                     Don't check for application updates during startup\n"
#endif
"  --gamelist-only                       Skip automatic game search, only read from gamelist.xml\n"
"  --ignore-gamelist                     Ignore the gamelist.xml files\n"
"  --show-hidden-files                   Show hidden files and folders\n"
"  --show-hidden-games                   Show hidden games\n"
"  --force-full                          Force the UI mode to Full\n"
"  --force-kiosk                         Force the UI mode to Kiosk\n"
"  --force-kid                           Force the UI mode to Kid\n"
"  --force-input-config                  Force configuration of input devices\n"
"  --create-system-dirs                  Create game system directories\n"
"  --home [path]                         Directory to use as home path\n"
"  --debug                               Enable debug mode\n"
"  --version, -v                         Display version information\n"
"  --help, -h                            Summon a sentient, angry tuba\n";
            // clang-format on
            return false;
        }
        else {
            const std::string argUnknown {arguments[i]};
            std::cout << "Unknown option '" << argUnknown << "'.\n";
            std::cout << "Try 'es-de --help' for more information.\n";
            return false;
        }
    }

    if (Settings::getInstance()->getBool("IgnoreGamelist")) {
        Settings::getInstance()->setBool("ParseGamelistOnly", false);
        settingsNeedSaving = true;
    }

    return true;
}

bool checkApplicationDataDirectory()
{
    // Check that the application data directory exists, otherwise create it.
    const std::string applicationData {Utils::FileSystem::getAppDataDirectory()};
    if (!Utils::FileSystem::exists(applicationData)) {
#if defined(__ANDROID__)
        __android_log_print(ANDROID_LOG_VERBOSE, ANDROID_APPLICATION_ID,
                            "First startup, creating application data directory \"%s\"",
                            applicationData.c_str());
#else
        std::cout << "First startup, creating application data directory \"" << applicationData
                  << "\"\n";
#endif
        Utils::FileSystem::createDirectory(applicationData);
        if (!Utils::FileSystem::exists(applicationData)) {
#if defined(__ANDROID__)
            __android_log_print(ANDROID_LOG_ERROR, ANDROID_APPLICATION_ID,
                                "Error: Couldn't create directory, permission problems?");
#else
            std::cerr << "Error: Couldn't create directory, permission problems?\n";
#endif
            return false;
        }
    }

    return true;
}

loadSystemsReturnCode loadSystemConfigFile()
{
    if (SystemData::loadConfig())
        return INVALID_FILE;

    if (SystemData::sSystemVector.size() == 0) {
        LOG(LogInfo) << "No game files were found, make sure that the system directories are "
                        "setup correctly and that the file extensions are supported";
        return NO_ROMS;
    }

    return LOADING_OK;
}

void onExit()
{
    // Called on exit, assuming we get far enough to have the log initialized.
    Log::close();
}

void applicationLoop()
{
#if !defined(__EMSCRIPTEN__)
    while (true) {
#endif
        if (SDL_PollEvent(&event)) {
            do {
                InputManager::getInstance().parseEvent(event);

                if (event.type == SDL_QUIT)
#if !defined(__EMSCRIPTEN__)
                    return;
#else
                SDL_Quit();
#endif
            } while (SDL_PollEvent(&event));
        }

        int curTime {static_cast<int>(SDL_GetTicks())};
        int deltaTime {curTime - lastTime};
        lastTime = curTime;

        // Cap deltaTime if it ever goes negative.
        if (deltaTime < 0)
            deltaTime = 1000;

        window->update(deltaTime);
        window->render();

        renderer->swapBuffers();
        Log::flush();
#if !defined(__EMSCRIPTEN__)
    }
#endif
}

int main(int argc, char* argv[])
{
    const auto applicationStartTime {std::chrono::system_clock::now()};

    std::locale::global(std::locale("C"));

#if defined(__ANDROID__)
    Utils::Platform::Android::setDataDirectories();
#endif

#if defined(__APPLE__)
    // This is a workaround to disable the incredibly annoying save state functionality in
    // macOS which forces a restore of the previous window state. The problem is that this
    // removes the splash screen on startup and it may have other adverse effects as well.
    std::string saveStateDir {Utils::FileSystem::expandHomePath(
        "~/Library/Saved Application State/org.es-de.Frontend.savedState")};
    // Deletion of the state files should normally not be required as there shouldn't be any
    // files to begin with. But maybe the files can still be created for unknown reasons
    // as macOS really really loves to restore windows. Let's therefore include this deletion
    // step as an extra precaution.
    if (Utils::FileSystem::exists(saveStateDir)) {
        for (std::string stateFile : Utils::FileSystem::getDirContent(saveStateDir))
            Utils::FileSystem::removeFile(stateFile);
    }
    else {
        Utils::FileSystem::createDirectory(saveStateDir);
    }
    // Removing the write permission from the save state directory effectively disables
    // the functionality.
    std::string chmodCommand {"chmod 500 \"" + saveStateDir + "\""};
    system(chmodCommand.c_str());
#endif

#if defined(_WIN64)
    // If we've been started from a console then redirect the standard streams there.
    outputToConsole();
#endif

    {
        std::vector<std::string> arguments;
        for (int i {0}; i < argc; ++i)
            arguments.emplace_back(argv[i]);
#if defined(_WIN64)
        if (!parseArguments(arguments)) {
            FreeConsole();
            return 0;
        }
#else
        if (!parseArguments(arguments)) {
            return 0;
        }
#endif
    }

    if (!Settings::getInstance()->getBool("DebugFlag") &&
        Settings::getInstance()->getBool("DebugMode")) {
        Settings::getInstance()->setBool("Debug", true);
        Log::setReportingLevel(LogDebug);
    }

#if defined(FREEIMAGE_LIB)
    // Call this ONLY when linking with FreeImage as a static library.
    FreeImage_Initialise();
#endif

    // If the application data directory doesn't exist and can't be created, then exit.
    if (!checkApplicationDataDirectory())
        return 1;

    {
        if (!Settings::getInstance()->getBool("LegacyAppDataDirectory")) {
            // Create the logs folder in the application data directory.
            const std::string logsDir {Utils::FileSystem::getAppDataDirectory() + "/logs"};
            if (!Utils::FileSystem::isDirectory(logsDir)) {
#if defined(__ANDROID__)
                __android_log_print(ANDROID_LOG_VERBOSE, ANDROID_APPLICATION_ID,
                                    "Creating logs directory \"%s\"...", logsDir.c_str());
#else
                std::cout << "Creating logs directory \"" << logsDir << "\"..." << std::endl;
#endif
                Utils::FileSystem::createDirectory(logsDir);
                if (!Utils::FileSystem::isDirectory(logsDir)) {
#if defined(__ANDROID__)
                    __android_log_print(ANDROID_LOG_ERROR, ANDROID_APPLICATION_ID,
                                        "Couldn't create directory, permission problems?");
#else
                    std::cerr << "Couldn't create directory, permission problems?" << std::endl;
#endif
                }
                else {
                    // Remove any old logs in the root of the directory.
                    Utils::FileSystem::removeFile(Utils::FileSystem::getAppDataDirectory() +
                                                  "/es_log.txt");
                    Utils::FileSystem::removeFile(Utils::FileSystem::getAppDataDirectory() +
                                                  "/es_log.txt.bak");
                }
            }
        }
    }

    // Start the logger.
    Log::init();
    Log::open();
    LOG(LogInfo) << "ES-DE v" << PROGRAM_VERSION_STRING << " (r" << PROGRAM_RELEASE_NUMBER
                 << "), built " << PROGRAM_BUILT_STRING;
    if (portableMode) {
        LOG(LogInfo) << "Running in portable mode";
        Settings::getInstance()->setBool("PortableMode", true);
    }
    else {
        Settings::getInstance()->setBool("PortableMode", false);
    }

    // Always close the log on exit.
    atexit(&onExit);

    if (createSystemDirectories) {
        if (!SystemData::createSystemDirectories() && !Settings::getInstance()->getBool("Debug"))
            std::cout << "System directories successfully created" << std::endl;
        LOG(LogInfo) << "ES-DE cleanly shutting down";
#if defined(_WIN64)
        FreeConsole();
#endif
        return 0;
    }

    Scripting::fireEvent("startup");

#if defined(__EMSCRIPTEN__)
    // TODO: Remove when application window resizing has been implemented.
    Settings::getInstance()->setBool("Debug", true);
    Log::setReportingLevel(LogDebug);
    Settings::getInstance()->setInt("ScreenWidth", 1280);
    Settings::getInstance()->setInt("ScreenHeight", 720);
#endif

    bool migratedSettings {false};

    {
        if (!Settings::getInstance()->getBool("LegacyAppDataDirectory")) {
            // Create the settings folder in the application data directory.
            const std::string settingsDir {Utils::FileSystem::getAppDataDirectory() + "/settings"};
            if (!Utils::FileSystem::isDirectory(settingsDir)) {
                LOG(LogInfo) << "Creating settings directory \"" << settingsDir << "\"...";
                Utils::FileSystem::createDirectory(settingsDir);
                if (!Utils::FileSystem::isDirectory(settingsDir)) {
                    LOG(LogError) << "Couldn't create directory, permission problems?";
                }
            }
            std::string settingsPathOld;
            std::string settingsPathNew;
            settingsPathOld = Utils::FileSystem::getAppDataDirectory() + "/es_settings.xml";
            settingsPathNew =
                Utils::FileSystem::getAppDataDirectory() + "/settings/es_settings.xml";
            if (!Utils::FileSystem::exists(settingsPathNew) &&
                Utils::FileSystem::exists(settingsPathOld)) {
                Utils::FileSystem::renameFile(settingsPathOld, settingsPathNew, false);
                Settings::getInstance()->loadFile();
                migratedSettings = true;
            }
            settingsPathOld = Utils::FileSystem::getAppDataDirectory() + "/es_input.xml";
            settingsPathNew = Utils::FileSystem::getAppDataDirectory() + "/settings/es_input.xml";
            if (!Utils::FileSystem::exists(settingsPathNew) &&
                Utils::FileSystem::exists(settingsPathOld)) {
                Utils::FileSystem::renameFile(settingsPathOld, settingsPathNew, false);
                migratedSettings = true;
            }
        }
    }

    {
        // Check if the es_settings.xml file exists, and if not, create it.
        std::string settingsPath;
        if (Settings::getInstance()->getBool("LegacyAppDataDirectory"))
            settingsPath = Utils::FileSystem::getAppDataDirectory() + "/es_settings.xml";
        else
            settingsPath = Utils::FileSystem::getAppDataDirectory() + "/settings/es_settings.xml";

        if (!Utils::FileSystem::exists(settingsPath)) {
            LOG(LogInfo) << "Settings file es_settings.xml does not exist, creating it...";
            Settings::getInstance()->saveFile();
        }
        else if (settingsNeedSaving) {
            LOG(LogInfo) << "Saving settings that were modified by command line options...";
            Settings::getInstance()->saveFile();
        }
    }

    {
        // Check if the application release number has changed, which would normally mean that the
        // user has upgraded to a new version.
        int applicationRelease;
        if ((applicationRelease = Settings::getInstance()->getInt("ApplicationRelease")) !=
            PROGRAM_RELEASE_NUMBER) {
            if (applicationRelease != 0) {
                LOG(LogInfo) << "Application release number changed from previous startup, from \""
                             << applicationRelease << "\" to \"" << PROGRAM_RELEASE_NUMBER << "\"";
            }
            else {
                LOG(LogInfo) << "Application release number setting is blank, changing it to \""
                             << PROGRAM_RELEASE_NUMBER << "\"";
            }
            Settings::getInstance()->setInt("ApplicationRelease", PROGRAM_RELEASE_NUMBER);
            Settings::getInstance()->saveFile();
        }
    }

    {
        // Create the gamelists folder in the application data directory.
        const std::string gamelistsDir {Utils::FileSystem::getAppDataDirectory() + "/gamelists"};
        if (!Utils::FileSystem::exists(gamelistsDir)) {
            LOG(LogInfo) << "Creating gamelists directory \"" << gamelistsDir << "\"...";
            Utils::FileSystem::createDirectory(gamelistsDir);
            if (!Utils::FileSystem::exists(gamelistsDir)) {
                LOG(LogWarning) << "Couldn't create directory, permission problems?";
            }
        }
    }

    {
#if defined(__ANDROID__)
        const std::string themeDir {Utils::FileSystem::getAppDataDirectory() + "/themes"};
        if (!Utils::FileSystem::exists(themeDir)) {
            LOG(LogInfo) << "Creating themes directory \"" << themeDir << "\"...";

            Utils::FileSystem::createDirectory(themeDir);
            if (!Utils::FileSystem::exists(themeDir)) {
                LOG(LogWarning) << "Couldn't create directory, permission problems?";
            }
        }
#else
        // Create the themes folder in the application data directory (or elsewhere if the
        // UserThemeDirectory setting has been defined).
        const std::string defaultUserThemeDir {Utils::FileSystem::getAppDataDirectory() +
                                               "/themes"};
        std::string userThemeDirSetting {Utils::FileSystem::expandHomePath(
            Settings::getInstance()->getString("UserThemeDirectory"))};
        std::string userThemeDirectory;

        if (userThemeDirSetting.empty())
            userThemeDirectory = defaultUserThemeDir;
        else
            userThemeDirectory = userThemeDirSetting;

        if (!Utils::FileSystem::exists(userThemeDirectory)) {
            LOG(LogInfo) << "Creating themes directory \"" << userThemeDirectory << "\"...";

            Utils::FileSystem::createDirectory(userThemeDirectory);
            if (!Utils::FileSystem::exists(userThemeDirectory)) {
                LOG(LogWarning) << "Couldn't create directory, permission problems?";
            }
        }
#endif
    }

    {
        // Create the scripts folder in the application data directory. This is only required
        // for custom event scripts so it's also created as a convenience.
        const std::string scriptsDir {Utils::FileSystem::getAppDataDirectory() + "/scripts"};
        if (!Utils::FileSystem::exists(scriptsDir)) {
            LOG(LogInfo) << "Creating scripts directory \"" << scriptsDir << "\"...";
            Utils::FileSystem::createDirectory(scriptsDir);
            if (!Utils::FileSystem::exists(scriptsDir)) {
                LOG(LogWarning) << "Couldn't create directory, permission problems?";
            }
        }
    }

    {
        // Create the screensavers and screensavers/custom_slideshow directories.
        const std::string screensaversDir {Utils::FileSystem::getAppDataDirectory() +
                                           "/screensavers"};
        const std::string slideshowDir {Utils::FileSystem::getAppDataDirectory() +
                                        "/screensavers/custom_slideshow"};
        if (!Utils::FileSystem::exists(screensaversDir)) {
            LOG(LogInfo) << "Creating screensavers directory \"" << screensaversDir << "\"...";
            Utils::FileSystem::createDirectory(screensaversDir);
            if (!Utils::FileSystem::exists(screensaversDir)) {
                LOG(LogWarning) << "Couldn't create directory, permission problems?";
            }
        }
        if (!Utils::FileSystem::exists(slideshowDir)) {
            LOG(LogInfo) << "Creating custom_slideshow directory \"" << slideshowDir << "\"...";
            Utils::FileSystem::createDirectory(slideshowDir);
            if (!Utils::FileSystem::exists(slideshowDir)) {
                LOG(LogWarning) << "Couldn't create directory, permission problems?";
            }
        }
    }

    {
        if (!Settings::getInstance()->getBool("LegacyAppDataDirectory")) {
            // Create the controllers folder in the application data directory.
            const std::string controllersDir {Utils::FileSystem::getAppDataDirectory() +
                                              "/controllers"};
            if (!Utils::FileSystem::exists(controllersDir)) {
                LOG(LogInfo) << "Creating controllers directory \"" << controllersDir << "\"...";
                Utils::FileSystem::createDirectory(controllersDir);
                if (!Utils::FileSystem::exists(controllersDir)) {
                    LOG(LogWarning) << "Couldn't create directory, permission problems?";
                }
            }
            std::string configPathOld {Utils::FileSystem::getAppDataDirectory() +
                                       "/es_controller_mappings.cfg"};
            std::string configPathNew {Utils::FileSystem::getAppDataDirectory() +
                                       "/controllers/es_controller_mappings.cfg"};
            if (!Utils::FileSystem::exists(configPathNew) &&
                Utils::FileSystem::exists(configPathOld)) {
                Utils::FileSystem::renameFile(configPathOld, configPathNew, false);
                migratedSettings = true;
            }
        }
    }

    renderer = Renderer::getInstance();
    window = Window::getInstance();

    ViewController::getInstance()->setMenuColors();
    CollectionSystemsManager::getInstance();
    Screensaver screensaver;
    MediaViewer mediaViewer;
    PDFViewer pdfViewer;
    GuiLaunchScreen guiLaunchScreen;

    if (!window->init()) {
        LOG(LogError) << "Window failed to initialize";
        return 1;
    }

#if defined(__ANDROID__)
    LOG(LogDebug) << "Android API level: " << SDL_GetAndroidSDKVersion();
    LOG(LogDebug) << "Android storage state: " << SDL_AndroidGetExternalStorageState();
    LOG(LogDebug) << "Android internal path: " << SDL_AndroidGetInternalStoragePath();
    LOG(LogDebug) << "Android external path: " << SDL_AndroidGetExternalStoragePath();
    {
        std::string buildIdentifier {PROGRAM_VERSION_STRING};
        buildIdentifier.append(" (r")
            .append(std::to_string(PROGRAM_RELEASE_NUMBER))
            .append("), built ")
            .append(PROGRAM_BUILT_STRING);
        if (Utils::Platform::Android::checkNeedResourceCopy(buildIdentifier)) {
            LOG(LogInfo) << "Application has been updated or it's a new installation, copying "
                            "bundled resources and themes to internal storage...";
            if (Settings::getInstance()->getBool("SplashScreen"))
                window->renderSplashScreen(Window::SplashScreenState::RESOURCE_COPY, 0.0f);
            if (Utils::Platform::Android::setupResources(buildIdentifier)) {
                LOG(LogError) << "Copying of resources and themes failed";
                return -1;
            }
        }
    }
#endif

#if defined(APPLICATION_UPDATER)
    if (!noUpdateCheck)
        ApplicationUpdater::getInstance().checkForUpdates();
#endif

    window->pushGui(ViewController::getInstance());

    if (Settings::getInstance()->getBool("SplashScreen"))
        window->renderSplashScreen(Window::SplashScreenState::SCANNING, 0.0f);

    while (SDL_PollEvent(&event)) {};

#if defined(_WIN64)
    // Hide taskbar if the setting for this is enabled.
    bool taskbarStateChanged {false};
    unsigned int taskbarState {0};

    if (Settings::getInstance()->getBool("HideTaskbar")) {
        taskbarStateChanged = true;
        taskbarState = Utils::Platform::getTaskbarState();
        Utils::Platform::hideTaskbar();
    }
#endif

    AudioManager::getInstance();

    SDL_version version;
    SDL_GetVersion(&version);

    LOG(LogInfo) << "SDL version: " << std::to_string(version.major) << "."
                 << std::to_string(version.minor) << "." << std::to_string(version.patch);

    if (version.major > 2 || (version.major == 2 && version.minor >= 28)) {
        // This will prevent the popup virtual keyboard of any handheld device from being
        // automatically displayed on top of the ES-DE virtual keyboard.
#define SDL_HINT_ENABLE_SCREEN_KEYBOARD "SDL_ENABLE_SCREEN_KEYBOARD"
        SDL_SetHint(SDL_HINT_ENABLE_SCREEN_KEYBOARD, "0");
    }

#if defined(__ANDROID__)
    Utils::Platform::Android::requestStoragePermission();
    Utils::Platform::Android::setROMDirectory();
#endif

    MameNames::getInstance();
    ThemeData::populateThemes();
    loadSystemsReturnCode loadSystemsStatus {loadSystemConfigFile()};

    if (!SystemData::sStartupExitSignal) {
        if (loadSystemsStatus) {
            // If there was an issue parsing the es_systems.xml file, display an error message.
            // If there were no game files found, give the option to the user to quit or to
            // configure a different ROM directory as well as to generate the game systems
            // directory structure.
            if (loadSystemsStatus == INVALID_FILE) {
                ViewController::getInstance()->invalidSystemsFileDialog();
            }
            else if (loadSystemsStatus == NO_ROMS) {
                ViewController::getInstance()->noGamesDialog();
            }
        }

        // Don't generate controller events while we're loading.
        SDL_GameControllerEventState(SDL_DISABLE);

        // Preload system view and all gamelist views.
        ViewController::getInstance()->preload();
    }

    if (!SystemData::sStartupExitSignal) {
        if (loadSystemsStatus == loadSystemsReturnCode::LOADING_OK)
            ThemeData::themeLoadedLogOutput();

        if (!loadSystemsStatus)
            ViewController::getInstance()->goToStart(true);

        // Check if any of the enabled systems have an invalid alternative emulator entry,
        // which means that a label is present in the gamelist.xml file which is not matching
        // any command tag in es_systems.xml.
        for (auto system : SystemData::sSystemVector) {
            if (system->getAlternativeEmulator().substr(0, 9) == "<INVALID>") {
                ViewController::getInstance()->invalidAlternativeEmulatorDialog();
                break;
            }
        }

        // Generate controller events since we're done loading.
        SDL_GameControllerEventState(SDL_ENABLE);

        lastTime = SDL_GetTicks();

#if defined(APPLICATION_UPDATER)
        if (ApplicationUpdater::getInstance().getResults())
            ViewController::getInstance()->updateAvailableDialog();
#endif

#if defined(_WIN64)
        if (Settings::getInstance()->getBool("PortableMode")) {
            // If it's the portable Windows release then create a release file, and check if there
            // are any release files from different versions than the one currently running.
            // If this is the case an unsafe upgrade has taken place, probably by simply unpacking
            // the new release on top of the old one.
            bool releaseFileExists {true};
            const std::filesystem::path releaseFile {Utils::FileSystem::getExePath() + "/r" +
                                                     std::to_string(PROGRAM_RELEASE_NUMBER) +
                                                     ".rel"};
            if (!Utils::FileSystem::exists(releaseFile.string()))
                releaseFileExists = Utils::FileSystem::createEmptyFile(releaseFile);
            if (releaseFileExists) {
                for (auto& file : Utils::FileSystem::getMatchingFiles(
                         Utils::FileSystem::getExePath() + "/*.rel")) {
                    if (Utils::FileSystem::getFileName(file) != releaseFile.filename()) {
                        LOG(LogWarning) << "It seems as if an unsafe upgrade has been made";
                        ViewController::getInstance()->unsafeUpgradeDialog();
                        break;
                    }
                }
            }
        }
#endif

        if (Settings::getInstance()->getBool("LegacyAppDataDirectory"))
            ViewController::getInstance()->legacyAppDataDialog();

        if (migratedSettings) {
            LOG(LogInfo) << "Migrated settings from a legacy application data directory structure";
            ViewController::getInstance()->migratedAppDataFilesDialog();
        }

        LOG(LogInfo) << "Application startup time: "
                     << std::chrono::duration_cast<std::chrono::milliseconds>(
                            std::chrono::system_clock::now() - applicationStartTime)
                            .count()
                     << " ms";

        // Open the input configuration GUI if the force flag was passed from the command line.
        if (forceInputConfig) {
            ViewController::getInstance()->cancelViewTransitions();
            window->pushGui(new GuiDetectDevice(false, true, nullptr));
        }

        // Main application loop.

        if (!SystemData::sStartupExitSignal) {
#if defined(__EMSCRIPTEN__)
            emscripten_set_main_loop(&applicationLoop, 0, 1);
#else
            applicationLoop();
#endif
        }
    }
    else {
        LOG(LogInfo) << "Exit signal received, aborting application startup";
    }

    while (window->peekGui() != ViewController::getInstance())
        delete window->peekGui();
    window->deinit();

    TextureResource::setExit();
    CollectionSystemsManager::getInstance()->deinit(true);
    SystemData::deleteSystems();
    NavigationSounds::getInstance().deinit();

#if defined(FREEIMAGE_LIB)
    // Call this ONLY when linking with FreeImage as a static library.
    FreeImage_DeInitialise();
#endif

#if defined(_WIN64)
    // If the taskbar state was changed (taskbar was hidden), then revert it.
    if (taskbarStateChanged)
        Utils::Platform::revertTaskbarState(taskbarState);
#endif

    Utils::Platform::processQuitMode();

    LOG(LogInfo) << "ES-DE cleanly shutting down";

#if defined(_WIN64)
    FreeConsole();
#endif

    return 0;
}