using System;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Runtime.InteropServices;
using System.Threading;
using System.Threading.Tasks;
using System.Windows;
using H.NotifyIcon;
using Microsoft.Extensions.DependencyInjection;
using Serilog;
using Windows.Storage;
using Wino.Calendar.Services;
using Wino.Core;
using Wino.Core.Domain;
using Wino.Core.Domain.Enums;
using Wino.Core.Domain.Interfaces;
using Wino.Core.UWP.Services;
using Wino.Server.Core;
using Wino.Server.MessageHandlers;
using Wino.Services;

namespace Wino.Server;

/// <summary>
/// Single instance Wino Server.
/// Instancing is done using Mutex.
/// App will not start if another instance is already running.
/// App will let running server know that server execution is triggered, which will
/// led server to start new connection to requesting UWP app.
/// </summary>
public partial class App : Application
{
    [DllImport("user32.dll", SetLastError = true, CharSet = CharSet.Unicode)]
    static extern IntPtr FindWindowEx(IntPtr hwndParent, IntPtr hwndChildAfter, string lpszClass, string lpszWindow);

    [DllImport("user32.dll", SetLastError = true, CharSet = CharSet.Unicode)]
    static extern uint GetWindowThreadProcessId(IntPtr hWnd, out uint lpdwProcessId);

    private const string FRAME_WINDOW = "ApplicationFrameWindow";

    public const string WinoMailLaunchProtocol = "wino.mail.launch";
    public const string WinoCalendarLaunchProtocol = "wino.calendar.launch";

    private const string NotifyIconResourceKey = "NotifyIcon";


    private const string WinoMailServerAppName = "Wino.Mail.Server";
    private const string WinoMailServerActivatedName = "Wino.Mail.Server.Activated";

    private const string WinoCalendarServerAppName = "Wino.Calendar.Server";
    private const string WinoCalendarServerActivatedName = "Wino.Calendar.Server.Activated";
    public new static App Current => (App)Application.Current;

    public WinoAppType WinoServerType { get; private set; }

    private TaskbarIcon? _notifyIcon;
    private static Mutex _mutex = null;
    private EventWaitHandle _eventWaitHandle;

    public IServiceProvider Services { get; private set; }

    private ServiceProvider ConfigureServices()
    {
        var services = new ServiceCollection();

        services.AddTransient<ServerContext>();
        services.AddTransient<ServerViewModel>();

        services.RegisterCoreServices();
        services.RegisterSharedServices();

        // Below services belongs to UWP.Core package and some APIs are not available for WPF.
        // We register them here to avoid compilation errors.

        services.AddSingleton<IConfigurationService, ConfigurationService>();
        services.AddSingleton<INativeAppService, NativeAppService>();
        services.AddSingleton<IPreferencesService, PreferencesService>();
        services.AddTransient<INotificationBuilder, NotificationBuilder>();
        services.AddTransient<IUnderlyingThemeService, UnderlyingThemeService>();
        services.AddSingleton<IApplicationConfiguration, ApplicationConfiguration>();
        services.AddSingleton<IThumbnailService, ThumbnailService>();

        // Register server message handler factory.
        var serverMessageHandlerFactory = new ServerMessageHandlerFactory();
        serverMessageHandlerFactory.Setup(services);

        services.AddSingleton<IServerMessageHandlerFactory>(serverMessageHandlerFactory);

        // Server type related services.
        // TODO: Better abstraction.

        if (WinoServerType == WinoAppType.Mail)
        {
            services.AddSingleton<IAuthenticatorConfig, MailAuthenticatorConfiguration>();
        }
        else
        {
            services.AddSingleton<IAuthenticatorConfig, CalendarAuthenticatorConfig>();
        }

        return services.BuildServiceProvider();
    }

    private async Task<ServerViewModel> InitializeNewServerAsync()
    {
        // Make sure app config is setup before anything else.
        var applicationFolderConfiguration = Services.GetService<IApplicationConfiguration>();

        applicationFolderConfiguration.ApplicationDataFolderPath = ApplicationData.Current.LocalFolder.Path;
        applicationFolderConfiguration.PublisherSharedFolderPath = ApplicationData.Current.GetPublisherCacheFolder(ApplicationConfiguration.SharedFolderName).Path;
        applicationFolderConfiguration.ApplicationTempFolderPath = ApplicationData.Current.TemporaryFolder.Path;

        // Setup logger
        var logInitializer = Services.GetService<IWinoLogger>();
        var logFilePath = Path.Combine(ApplicationData.Current.LocalFolder.Path, Constants.ServerLogFile);

        logInitializer.SetupLogger(logFilePath);

        // Make sure the database is ready.
        var databaseService = Services.GetService<IDatabaseService>();
        await databaseService.InitializeAsync();

        // Setup core window handler for native app service.
        // WPF app uses UWP app's window handle to display authentication dialog.
        var nativeAppService = Services.GetService<INativeAppService>();
        nativeAppService.GetCoreWindowHwnd = FindUWPClientWindowHandle;

        // Initialize translations.
        var translationService = Services.GetService<ITranslationService>();
        await translationService.InitializeAsync();

        // Make sure all accounts have synchronizers.
        var synchronizerFactory = Services.GetService<ISynchronizerFactory>();
        await synchronizerFactory.InitializeAsync();

        // Load up the server view model.
        var serverViewModel = Services.GetRequiredService<ServerViewModel>();
        await serverViewModel.InitializeAsync();

        return serverViewModel;
    }

    /// <summary>
    /// OutlookAuthenticator for WAM requires window handle to display the dialog.
    /// Since server app is windowless, we need to find the UWP app window handle.
    /// </summary>
    /// <param name="proc"></param>
    /// <returns>Pointer to running UWP app's hwnd.</returns>
    private IntPtr FindUWPClientWindowHandle()
    {
        string processName = WinoServerType == WinoAppType.Mail ? "Wino.Mail" : "Wino.Calendar";

        var proc = Process.GetProcessesByName(processName).FirstOrDefault() ?? throw new Exception($"{processName} client is not running.");

        for (IntPtr appWindow = FindWindowEx(IntPtr.Zero, IntPtr.Zero, FRAME_WINDOW, null); appWindow != IntPtr.Zero;
            appWindow = FindWindowEx(IntPtr.Zero, appWindow, FRAME_WINDOW, null))
        {
            IntPtr coreWindow = FindWindowEx(appWindow, IntPtr.Zero, "Windows.UI.Core.CoreWindow", null);
            if (coreWindow != IntPtr.Zero)
            {
                if (GetWindowThreadProcessId(coreWindow, out var corePid) == 0)
                {
                    throw new System.ComponentModel.Win32Exception(Marshal.GetLastWin32Error());
                }
                if (corePid == proc.Id)
                {
                    return appWindow;
                }
            }
        }

        return IntPtr.Zero;
    }

    protected override async void OnStartup(StartupEventArgs e)
    {
        // Same server code runs for both Mail and Calendar.

        string winoAppTypeParameter = e.Args.Length > 0 ? e.Args[^1] : "Mail";

        WinoServerType = winoAppTypeParameter == "Mail" ? WinoAppType.Mail : WinoAppType.Calendar;

        // TODO: Better abstraction.

        string serverName = WinoServerType == WinoAppType.Mail ? WinoMailServerAppName : WinoCalendarServerAppName;
        string serverActivatedName = WinoServerType == WinoAppType.Mail ? WinoMailServerActivatedName : WinoCalendarServerActivatedName;

        _mutex = new Mutex(true, serverName, out bool isCreatedNew);
        _eventWaitHandle = new EventWaitHandle(false, EventResetMode.AutoReset, serverActivatedName);

        if (isCreatedNew)
        {
            AppDomain.CurrentDomain.UnhandledException += ServerCrashed;
            Application.Current.DispatcherUnhandledException += UIThreadCrash;
            TaskScheduler.UnobservedTaskException += TaskCrashed;

            // Ensure proper encodings are available for MimeKit
            System.Text.Encoding.RegisterProvider(System.Text.CodePagesEncodingProvider.Instance);

            // Spawn a thread which will be waiting for our event
            var thread = new Thread(() =>
            {
                while (_eventWaitHandle.WaitOne())
                {
                    if (_notifyIcon == null) return;

                    Current.Dispatcher.BeginInvoke(async () =>
                    {
                        if (_notifyIcon.DataContext is ServerViewModel trayIconViewModel)
                        {
                            await trayIconViewModel.ReconnectAsync();
                        }
                    });
                }
            })
            {
                // It is important mark it as background otherwise it will prevent app from exiting.
                IsBackground = true
            };
            thread.Start();

            Services = ConfigureServices();

            base.OnStartup(e);

            var serverViewModel = await InitializeNewServerAsync();

            // Create taskbar icon for the new server.
            _notifyIcon = (TaskbarIcon)FindResource(NotifyIconResourceKey);
            _notifyIcon.DataContext = serverViewModel;
            _notifyIcon.ForceCreate(enablesEfficiencyMode: true);

            // Hide the icon if user has set it to invisible.
            var preferencesService = Services.GetService<IPreferencesService>();
            ChangeNotifyIconVisiblity(preferencesService.ServerTerminationBehavior != ServerBackgroundMode.Invisible);
        }
        else
        {
            // Notify other instance so it could reconnect to UWP app if needed.
            _eventWaitHandle.Set();

            // Terminate this instance.
            Shutdown();
        }
    }

    private void TaskCrashed(object sender, UnobservedTaskExceptionEventArgs e) => Log.Error(e.Exception, "Server task crashed.");

    private void UIThreadCrash(object sender, System.Windows.Threading.DispatcherUnhandledExceptionEventArgs e) => Log.Error(e.Exception, "Server UI thread crashed.");

    private void ServerCrashed(object sender, UnhandledExceptionEventArgs e) => Log.Error((Exception)e.ExceptionObject, "Server crashed.");

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

    public void ChangeNotifyIconVisiblity(bool isVisible)
    {
        if (_notifyIcon == null) return;

        Current.Dispatcher.BeginInvoke(() =>
        {
            _notifyIcon.Visibility = isVisible ? Visibility.Visible : Visibility.Collapsed;
        });
    }
}