using System.IO;
using System.Windows;
using System.Windows.Interop;

namespace DeskCore;

public partial class App : Application
{
    private const string MutexName = "DeskCore.Instanz";
    private const string ShowEventName = "DeskCore.Anzeigen";

    public static MainWindow? Win { get; private set; }
    public static Tray? TrayIcon { get; private set; }
    public static bool Quitting { get; private set; }

    private static Hotkey? _hotkey;
    private static Watcher? _watcher;
    private Mutex? _mutex;
    private EventWaitHandle? _showEvent;

    protected override void OnStartup(StartupEventArgs e)
    {
        // Nur eine Instanz: eine zweite holt einfach das vorhandene Fenster nach vorne
        _mutex = new Mutex(true, MutexName, out bool first);
        if (!first)
        {
            try { EventWaitHandle.OpenExisting(ShowEventName).Set(); } catch { }
            Shutdown();
            return;
        }
        Migration.Run(); // alte "Desktop Sortierer"-Ordner übernehmen – vor allem anderen
        _showEvent = new EventWaitHandle(false, EventResetMode.AutoReset, ShowEventName);
        new Thread(() =>
        {
            while (_showEvent.WaitOne())
                Dispatcher.BeginInvoke(() => Win?.ShowFromBackground());
        }) { IsBackground = true, Name = "ShowListener" }.Start();

        DispatcherUnhandledException += (_, args) =>
        {
            var log = Path.Combine(Storage.Root, "fehler.log");
            try { File.AppendAllText(log, $"[{DateTime.Now}] {args.Exception}\n\n"); } catch { }
            MessageBox.Show($"Unerwarteter Fehler:\n\n{args.Exception.Message}\n\nDetails: {log}", "DeskCore",
                MessageBoxButton.OK, MessageBoxImage.Error);
            args.Handled = true;
        };

        base.OnStartup(e);
        ShutdownMode = ShutdownMode.OnExplicitShutdown;

        Storage.FlushHolding(); // Reste eines Absturzes in den Papierkorb
        Theme.Init();
        Theme.Changed += FenceManager.RefreshAll;

        Win = new MainWindow();
        MainWindow = Win;
        var hwnd = new WindowInteropHelper(Win).EnsureHandle();

        _hotkey = new Hotkey(hwnd);
        _hotkey.Pressed += () => Win.ToggleFromHotkey();
        ApplyHotkey();

        TrayIcon = new Tray();
        TrayIcon.Clicked += () => Win.ShowFromBackground();
        TrayIcon.BalloonClicked += () => Win.ShowFromBackground();
        TrayIcon.MenuRequested += () => Win.ShowTrayMenu();
        ApplyTray();

        _watcher = new Watcher(Dispatcher);
        _watcher.Changed += () =>
        {
            Win.OnStorageChanged();
            FenceManager.RefreshAll();
        };
        _watcher.NewOnDesktop += Win.AutoSortNew;

        Autostart.RefreshPath();

        bool minimized = e.Args.Contains("--minimized", StringComparer.OrdinalIgnoreCase);
        if (!minimized || !AppSettings.Current.TrayEnabled) Win.Show();
        FenceManager.Sync();
    }

    /// <summary>Tastenkürzel neu registrieren. false = von anderem Programm belegt.</summary>
    public static bool ApplyHotkey()
    {
        if (_hotkey is null) return false;
        var s = AppSettings.Current;
        if (!s.HotkeyEnabled) { _hotkey.Unregister(); return true; }
        return _hotkey.Register(s.HotkeyModifiers, s.HotkeyKey);
    }

    public static void ApplyTray()
    {
        if (TrayIcon is not null) TrayIcon.Visible = AppSettings.Current.TrayEnabled;
    }

    public static void Quit()
    {
        if (Quitting) return;
        Quitting = true;
        Win?.Undo.FlushAll();
        FenceManager.CloseAll();
        _watcher?.Dispose();
        _hotkey?.Dispose();
        TrayIcon?.Dispose();
        Win?.Close();
        Current.Shutdown();
    }

    protected override void OnExit(ExitEventArgs e)
    {
        TrayIcon?.Dispose();
        _mutex?.Dispose();
        base.OnExit(e);
    }
}