using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using MultiTerm.Core.ViewModel;
using System.Windows;
using MultiTerm.Core.Helpers;
using Common.Logging;
using System;
using System.Threading.Tasks;
using Common.AppSettings;
using MultiTerm.Protocols.Helpers;
using CommunityToolkit.Mvvm.Messaging;
using Common;
using System.IO;

namespace MultiTerm.Wpf;

public partial class App : Application
{
    private static ILogger? logger;

    public static IHost? AppHost { get; private set; }

    public App()
    {
        // create folder in appdata if it does not exist
        if (Directory.Exists(Common.BaseAppDataDirectory) == false) 
        {
            Directory.CreateDirectory(Common.BaseAppDataDirectory);
            Directory.CreateDirectory(Common.LogFilesDirectory);
        }

        // create dependency injection host
        AppHost = Host.CreateDefaultBuilder()
            .ConfigureServices((hostContext, services) =>
            {
                services.AddSingleton<MainWindow>();
                services.AddSingleton<IContext>(new WpfContext());
                services.AddSingleton<ILogger>(new SerilogLogger($"{Common.LogFilesDirectory}/{Common.LogFileName}", true));
                services.AddSingleton<IAppSettingsProvider>(new XmlAppSettingsProvider(Common.ConfigFilePath));
                services.AddSingleton<IMessenger, WeakReferenceMessenger>();

                // viewmodels
                services.AddSingleton<ShellViewModel>();

                // application specific
                services.AddCommunicationProtocolFactory();
                services.AddTerminalViewModelFactory();
            })
            .Build();
    }

    protected override async void OnStartup(StartupEventArgs e)
    {
        await AppHost!.StartAsync();

        // create logger and initialize
        logger = AppHost.Services.GetRequiredService<ILogger>();
        logger.Initialize(LogLevel.Trace);
        logger.LogInfo("Application started.", nameof(App));

        // register handlers to some hidden exception types
        AppDomain.CurrentDomain.UnhandledException += this.AppDomain_UnhandledException;
        Application.Current.DispatcherUnhandledException += this.Application_DispatcherUnhandledException;
        TaskScheduler.UnobservedTaskException += this.TaskScheduler_UnobservedTaskException;

        // register log events from AppSettingsProvider and load saved settings
        var appSettingsProvider = AppHost.Services.GetRequiredService<IAppSettingsProvider>();
        appSettingsProvider.LogWorthyEvent += AppSettingsProvider_LogWorthyEvent;
        appSettingsProvider.Load();

        // instanciate startup form and show
        var startupForm = AppHost.Services.GetRequiredService<MainWindow>();
        startupForm.Show();

        base.OnStartup(e);
    }

    private void AppSettingsProvider_LogWorthyEvent(object? sender, LogEntry e)
    {
        logger?.Log(e);
    }

    protected override async void OnExit(ExitEventArgs e)
    {
        // save settings to persistent location
        var appSettingsProvider = AppHost!.Services.GetRequiredService<IAppSettingsProvider>();
        appSettingsProvider.Save();

        // teardown of terminal views and communication protocol threads
        var shellViewModel = AppHost!.Services.GetRequiredService<ShellViewModel>();
        shellViewModel.Teardown();

        // log application exit and stop logger (if still available)
        logger?.LogInfo("Application exited.", nameof(App));
        logger?.StopLogging();

        await AppHost!.StopAsync();
        base.OnExit(e);
    }

    #region Event handlers for hidden exceptions
    private void AppDomain_UnhandledException(object sender, UnhandledExceptionEventArgs e)
    {
        logger?.LogException((Exception)e.ExceptionObject, "AppDomain UnhandledException occurred", nameof(App));
        MessageBox.Show("Please check logfile. Exception message: \n" + ((Exception)e.ExceptionObject).Message, "AppDomain UnhandledException occurred", MessageBoxButton.OK, MessageBoxImage.Warning);
    }

    private void Application_DispatcherUnhandledException(object sender, System.Windows.Threading.DispatcherUnhandledExceptionEventArgs e)
    {
        logger?.LogException(e.Exception, "Application DispatcherUnhandledException occurred", nameof(App));
        MessageBox.Show("Please check logfile. Exception message: \n" + e.Exception.Message, "Application DispatcherUnhandledException occurred", MessageBoxButton.OK, MessageBoxImage.Warning);
    }

    private void TaskScheduler_UnobservedTaskException(object? sender, UnobservedTaskExceptionEventArgs e)
    {
        logger?.LogException(e.Exception, "TaskScheduler UnobservedTaskException occurred", nameof(App));
        MessageBox.Show("Please check logfile. Exception message: \n" + e.Exception.Message, "TaskScheduler UnobservedTaskException occurred", MessageBoxButton.OK, MessageBoxImage.Warning);
    }
    #endregion
}