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

namespace DeskCore;

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

    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 Hotkey? _peekHotkey;
    private static Hotkey? _pagePrev, _pageNext;
    private static System.Windows.Threading.DispatcherTimer? _desktopTimer;
    private static Watcher? _watcher;
    private Mutex? _mutex;

    protected override void OnStartup(StartupEventArgs e)
    {
        // Nur eine Instanz: weitere Aufrufe reichen ihren Befehl (oder "Fenster zeigen") an die laufende weiter
        _mutex = new Mutex(true, MutexName, out bool first);
        if (!first)
        {
            Commands.Send(e.Args);
            Shutdown();
            return;
        }
        Migration.Run(); // alte "Desktop Sortierer"-Ordner übernehmen – vor allem anderen
        Commands.Listen(args => Dispatcher.BeginInvoke(() => HandleCommand(args)));

        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();
        _peekHotkey = new Hotkey(hwnd, 0xB002);
        _peekHotkey.Pressed += FenceManager.TogglePeek;
        ApplyPeekHotkey();
        // Desktop-Seiten: Win + Alt + Pfeil links/rechts
        _pagePrev = new Hotkey(hwnd, 0xB003);
        _pagePrev.Pressed += () => FenceManager.NextPage(-1);
        _pagePrev.Register(Hotkey.ModWin | Hotkey.ModAlt, 0x25);
        _pageNext = new Hotkey(hwnd, 0xB004);
        _pageNext.Pressed += () => FenceManager.NextPage(1);
        _pageNext.Register(Hotkey.ModWin | Hotkey.ModAlt, 0x27);

        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();
            Win.ScheduleDeadShortcutScan(); // z. B. Deinstallation hat die Desktop-Verknüpfung entfernt
        };
        _watcher.NewOnDesktop += Win.AutoSortNew;

        Autostart.RefreshPath();

        // Mit einem Befehl gestartet (z. B. Start-Gruppe per Desktop-Verknüpfung)? Dann ohne Fenster.
        if (Commands.WantsWindow(e.Args) || !AppSettings.Current.TrayEnabled) Win.Show();
        FenceManager.Sync();

        // Bildschirm abgesteckt/Auflösung geändert → Fenster und Boxen wieder in den sichtbaren Bereich holen
        Microsoft.Win32.SystemEvents.DisplaySettingsChanged += (_, _) => Dispatcher.BeginInvoke(() =>
        {
            Win.EnsureOnScreen();
            FenceManager.OnDisplayChanged();
        });

        Win.CheckForUpdatesOnStartup();
        if (!Commands.WantsWindow(e.Args)) Dispatcher.BeginInvoke(() => HandleCommand(e.Args));
        Win.StartDeadShortcutWatch();
        DesktopToggle.Apply();

        // Positionen der Desktop-Icons regelmäßig lesen (für Aufziehen, Doppelklick und die Icon-Tönung)
        _desktopTimer = new System.Windows.Threading.DispatcherTimer { Interval = TimeSpan.FromSeconds(2) };
        _desktopTimer.Tick += (_, _) => RefreshDesktopIcons();
        _desktopTimer.Start();
        RefreshDesktopIcons();
    }

    private static void RefreshDesktopIcons()
    {
        var s = AppSettings.Current;
        if (Quitting) return;
        // Nur lesen, wenn eine Funktion die Positionen braucht
        if (s.DesktopTint is null && !s.DrawFences && !s.QuickHide) return;
        try { DesktopIcons.RefreshCache(); } catch { /* Explorer gerade neu gestartet o. Ä. */ }
        DesktopTint.Refresh();
    }

    /// <summary>Befehl von der Befehlszeile oder einem weiteren Aufruf ausführen.</summary>
    private static void HandleCommand(string[] args)
    {
        if (Win is null || Quitting) return;
        if (Commands.Value(args, "--launch") is { } group) Win.LaunchGroupByName(group);
        else if (Commands.Value(args, "--snapshot") is { } snap) Win.RestoreSnapshotByName(snap);
        else if (Commands.Has(args, "--toggle-desktop")) DesktopToggle.Toggle();
        else if (Commands.Has(args, "--peek")) FenceManager.TogglePeek();
        else if (Commands.Value(args, "--page") is { } page) SwitchPageByName(page);
        else if (Commands.WantsWindow(args)) Win.ShowFromBackground();
    }

    /// <summary>DeskCore.exe --page "Name" oder --page 2.</summary>
    private static void SwitchPageByName(string page)
    {
        var pages = AppSettings.Current.Pages;
        int i = pages.FindIndex(p => string.Equals(p, page, StringComparison.OrdinalIgnoreCase));
        if (i < 0 && int.TryParse(page, out var n)) i = n - 1;
        if (i >= 0 && i < pages.Count) FenceManager.SwitchPage(i);
        else TrayIcon?.Notify("Seite nicht gefunden", $"Es gibt keine Desktop-Seite „{page}“.");
    }

    /// <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);
    }

    /// <summary>Peek-Kürzel neu registrieren. false = von anderem Programm belegt.</summary>
    public static bool ApplyPeekHotkey()
    {
        if (_peekHotkey is null) return false;
        var s = AppSettings.Current;
        if (!s.PeekEnabled) { _peekHotkey.Unregister(); return true; }
        return _peekHotkey.Register(s.PeekModifiers, s.PeekKey);
    }

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

    public static void Quit()
    {
        if (Quitting) return;
        Quitting = true;
        Win?.CancelBusyAndWait(); // z. B. große Kopie abbrechen, halbe Dateien aufräumen
        Win?.SavePlacement();
        _desktopTimer?.Stop();
        DesktopToggle.Stop();
        DesktopToggle.RestoreOnExit();
        _peekHotkey?.Dispose();
        _pagePrev?.Dispose();
        _pageNext?.Dispose();
        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);
    }
}