using Microsoft.UI.Xaml;
using Microsoft.UI.Xaml.Controls;
using Microsoft.UI.Xaml.Data;
using Microsoft.UI.Xaml.Input;
using Microsoft.UI.Xaml.Media;
using Microsoft.UI.Xaml.Navigation;
using KronaStaffTerminal.Services;

// To learn more about WinUI, the WinUI project structure,
// and more about our project templates, see: http://aka.ms/winui-project-info.

namespace KronaStaffTerminal;

/// <summary>
/// Provides application-specific behavior to supplement the default Application class.
/// </summary>
public partial class App : Application
{
    private const string InstanceMutexName = @"Global\KronaStaffTerminal.Singleton";
    private const string ActivationEventName = @"Global\KronaStaffTerminal.Activate";
    private TrayService? _trayService;
    private Microsoft.UI.Dispatching.DispatcherQueueTimer? _autostartTimer;
    private Mutex? _instanceMutex;
    private EventWaitHandle? _activationEvent;
    private CancellationTokenSource? _activationCancellation;
    private Task? _activationTask;
    /// <summary>
    /// The main application window. Use <c>App.Window</c> from any class that needs
    /// the window reference (for dialogs, pickers, interop, etc.).
    /// </summary>
    public static Window Window { get; private set; } = null!;

    /// <summary>
    /// The UI thread dispatcher. Use <c>App.DispatcherQueue</c> to marshal calls
    /// to the UI thread. Fully qualified to avoid CS0104 ambiguity with
    /// <see cref="Windows.System.DispatcherQueue"/>.
    /// </summary>
    public static Microsoft.UI.Dispatching.DispatcherQueue DispatcherQueue { get; private set; } = null!;

    /// <summary>
    /// The native window handle (HWND). Use for file pickers,
    /// <c>DataTransferManager</c>, and any WinRT interop that requires
    /// <c>InitializeWithWindow</c>.
    /// </summary>
    public static nint WindowHandle =>
        WinRT.Interop.WindowNative.GetWindowHandle(Window);

    /// <summary>
    /// Initializes the singleton application object.
    /// </summary>
    public App()
    {
        InitializeComponent();
        UnhandledException += (_, eventArgs) => CrashLogService.Write(eventArgs.Exception);
        AppDomain.CurrentDomain.UnhandledException += (_, eventArgs) =>
        {
            if (eventArgs.ExceptionObject is Exception exception) CrashLogService.Write(exception);
        };
        TaskScheduler.UnobservedTaskException += (_, eventArgs) =>
        {
            CrashLogService.Write(eventArgs.Exception.Flatten());
            eventArgs.SetObserved();
        };
    }

    /// <summary>
    /// Invoked when the application is launched.
    /// </summary>
    /// <param name="args">Details about the launch request and process.</param>
    protected override void OnLaunched(Microsoft.UI.Xaml.LaunchActivatedEventArgs args)
    {
        _instanceMutex = new Mutex(true, InstanceMutexName, out var isFirstInstance);
        if (!isFirstInstance)
        {
            try
            {
                EventWaitHandle.OpenExisting(ActivationEventName).Set();
            }
            catch (WaitHandleCannotBeOpenedException)
            {
                // The first instance is still starting; exiting avoids competing for the scanner.
            }
            Environment.Exit(0);
            return;
        }

        Window = new MainWindow();
        DispatcherQueue = Microsoft.UI.Dispatching.DispatcherQueue.GetForCurrentThread();
        _trayService = new TrayService(ShowWindow, RequestExit, ShowWindow, RequestSync);
        _activationEvent = new EventWaitHandle(false, EventResetMode.AutoReset, ActivationEventName);
        _activationCancellation = new CancellationTokenSource();
        _activationTask = Task.Run(() => ListenForActivation(_activationCancellation.Token));
        Window.Activate();
        if (Environment.GetCommandLineArgs().Any(argument =>
                argument.Equals("--autostart", StringComparison.OrdinalIgnoreCase)))
        {
            _autostartTimer = DispatcherQueue.CreateTimer();
            _autostartTimer.Interval = TimeSpan.FromSeconds(1);
            _autostartTimer.IsRepeating = false;
            _autostartTimer.Tick += (_, _) =>
            {
                if (Window is MainWindow mainWindow)
                {
                    mainWindow.HideToTray();
                }
                _autostartTimer = null;
            };
            _autostartTimer.Start();
        }
    }

    private void ListenForActivation(CancellationToken cancellationToken)
    {
        while (!cancellationToken.IsCancellationRequested)
        {
            if (_activationEvent?.WaitOne(TimeSpan.FromSeconds(1)) == true)
            {
                if (cancellationToken.IsCancellationRequested) return;
                DispatcherQueue.TryEnqueue(ShowWindow);
            }
        }
    }

    public void NotifyMinimizedToTray() => _trayService?.ShowRunningBalloon();

    public void UpdateTray(TrayState state, int pendingCount, string? statusText = null) =>
        _trayService?.UpdateState(state, pendingCount, statusText);

    private static void ShowWindow()
    {
        if (Window is MainWindow mainWindow)
        {
            mainWindow.ShowWindow();
        }
    }

    private static void RequestSync()
    {
        if (Window is MainWindow mainWindow && mainWindow.Content is FrameworkElement fe && fe.FindName("RootFrame") is Microsoft.UI.Xaml.Controls.Frame frame && frame.Content is MainPage page)
        {
            _ = page.SyncPendingAttendanceAsync();
        }
    }

    private static void RequestExit()
    {
        if (Window is MainWindow mainWindow)
        {
            mainWindow.ShowWindow();
            _ = mainWindow.RequestExitAsync();
        }
    }

    public void CompleteExit()
    {
        _activationCancellation?.Cancel();
        _activationEvent?.Set();
        var activationStopped = true;
        try
        {
            activationStopped = _activationTask?.Wait(TimeSpan.FromSeconds(2)) != false;
        }
        catch (AggregateException exception)
        {
            CrashLogService.Write(exception.Flatten());
        }
        if (activationStopped)
        {
            _activationTask = null;
            _activationCancellation?.Dispose();
            _activationCancellation = null;
            _activationEvent?.Dispose();
            _activationEvent = null;
        }
        else
        {
            CrashLogService.Write(new TimeoutException("Слушатель активации не завершился; его ресурсы оставлены до выхода процесса."));
        }
        _instanceMutex?.ReleaseMutex();
        _instanceMutex?.Dispose();
        _instanceMutex = null;
        _trayService?.Dispose();
        _trayService = null;
        if (Window is MainWindow mainWindow)
        {
            mainWindow.ExitApplication();
        }
    }
}