using ApplicationServices;
using AppScaffolding;
using DataLayer;
using LibationFileManager;
using LibationUiBase;
using LibationWinForms.Dialogs;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace LibationWinForms
{
	static class Program
	{
		[System.Runtime.InteropServices.DllImport("kernel32.dll", SetLastError = true)]
		[return: System.Runtime.InteropServices.MarshalAs(System.Runtime.InteropServices.UnmanagedType.Bool)]
		static extern bool AllocConsole();

		private static Form1 form1;

		[STAThread]
		static void Main()
		{
			Task<List<LibraryBook>> libraryLoadTask;

			try
			{
				//// Uncomment to see Console. Must be called before anything writes to Console.
				//// Only use while debugging. Acts erratically in the wild
				//AllocConsole();

				// run as early as possible. see notes in postLoggingGlobalExceptionHandling
				Application.SetUnhandledExceptionMode(UnhandledExceptionMode.CatchException);

				ApplicationConfiguration.Initialize();

				//***********************************************//
				//                                               //
				//   do not use Configuration before this line   //
				//                                               //
				//***********************************************//
				// Migrations which must occur before configuration is loaded for the first time. Usually ones which alter the Configuration
				var config = AppScaffolding.LibationScaffolding.RunPreConfigMigrations();
				LibationUiBase.Forms.MessageBoxBase.ShowAsyncImpl = ShowMessageBox;

				// do this as soon as possible (post-config)
				RunSetupIfNeededAsync(config);

				// most migrations go in here
				LibationScaffolding.RunPostConfigMigrations(config);
				SetThemeColor(config);

				// migrations which require Forms or are long-running
				RunWindowsOnlyMigrations(config);

				//*******************************************************************//
				//                                                                   //
				//  Start loading the library as soon as possible                    //
				//                                                                   //
				//  Before calling anything else, including subscribing to events,   //
				//  to ensure database exists. If we wait and let it happen lazily,  //
				//  race conditions and errors are likely during new installs        //
				//                                                                   //
				//*******************************************************************//
				libraryLoadTask = Task.Run(() => DbContexts.GetLibrary_Flat_NoTracking(includeParents: true));

				MessageBoxLib.VerboseLoggingWarning_ShowIfTrue();

				// logging is init'd here
				LibationScaffolding.RunPostMigrationScaffolding(Variety.Classic, config);
			}
			catch (Exception ex)
			{
				var title = "Fatal error, pre-logging";
				var body = "An unrecoverable error occurred. Since this error happened before logging could be initialized, this error can not be written to the log file.";
				try
				{
					MessageBoxLib.ShowAdminAlert(null, body, title, ex);
				}
				catch
				{
					MessageBox.Show($"{body}\r\n\r\n{ex.Message}\r\n\r\n{ex.StackTrace}", title, MessageBoxButtons.OK, MessageBoxIcon.Error);
				}
				return;
			}

			// global exception handling (ShowAdminAlert) attempts to use logging. only call it after logging has been init'd
			postLoggingGlobalExceptionHandling();

			form1 = new Form1();
			form1.Load += async (_, _) => await form1.InitLibraryAsync(await libraryLoadTask);
			Application.Run(form1);
		}

		#region Message Box Handler for LibationUiBase
		static Task<LibationUiBase.Forms.DialogResult> ShowMessageBox(
			object owner,
			string message,
			string caption,
			LibationUiBase.Forms.MessageBoxButtons buttons,
			LibationUiBase.Forms.MessageBoxIcon icon,
			LibationUiBase.Forms.MessageBoxDefaultButton defaultButton,
			bool _)
		{
			Func<DialogResult> showMessageBox = () => MessageBox.Show(
					owner as IWin32Window ?? form1,
					message,
					caption,
					(MessageBoxButtons)buttons,
					(MessageBoxIcon)icon,
					(MessageBoxDefaultButton)defaultButton);


			var result = form1 is null ? showMessageBox() : form1.Invoke(showMessageBox);
			return Task.FromResult((LibationUiBase.Forms.DialogResult)result);
		}
		#endregion;

		private static void SetThemeColor(Configuration config)
		{
			var theme = config.ThemeVariant switch
			{
				Configuration.Theme.Light => SystemColorMode.Classic,
				Configuration.Theme.Dark => SystemColorMode.Dark,
				_ => SystemColorMode.System,
			};

			Application.SetColorMode(theme);
		}

		private static void RunSetupIfNeededAsync(Configuration config)
		{
			var setup = new LibationSetup(config.LibationFiles)
			{
				SetupPrompt = ShowSetup,
				SelectFolderPrompt = SelectInstallLocation
			};

			if (!setup.RunSetupIfNeededAsync().GetAwaiter().GetResult())
			{
				MessageBox.Show("Initial set up cancelled.", "Cancelled", MessageBoxButtons.OK, MessageBoxIcon.Warning);
				Application.Exit();
				Environment.Exit(-1);
			}

			static ILibationSetup ShowSetup()
			{
				var setupDialog = new SetupDialog();
				setupDialog.ShowDialog();
				return setupDialog;
			}

			static ILibationInstallLocation SelectInstallLocation()
			{
				var libationFilesDialog = new LibationFilesDialog();
				return libationFilesDialog.ShowDialog() is DialogResult.OK ? libationFilesDialog : null;
			}
		}

		/// <summary>migrations which require Forms or are long-running</summary>
		private static void RunWindowsOnlyMigrations(Configuration config)
		{
			// examples:
			// - only supported in winforms. don't move to app scaffolding
			// - long running. won't get a chance to finish in cli. don't move to app scaffolding

			const string hasMigratedKey = "hasMigratedToHighDPI";
			if (!config.GetNonString(defaultValue: false, hasMigratedKey))
			{
				config.RemoveProperty(nameof(config.GridColumnsWidths));

				foreach (var form in typeof(Program).Assembly.GetTypes().Where(t => t.IsSubclassOf(typeof(Form))))
					config.RemoveProperty(form.Name);

				config.SetNonString(true, hasMigratedKey);
			}
		}

		private static void postLoggingGlobalExceptionHandling()
		{
			// this line is all that's needed for strict handling
			AppDomain.CurrentDomain.UnhandledException += (_, e) => MessageBoxLib.ShowAdminAlert(null, "Libation has crashed due to an unhandled error.", "Application crash!", (Exception)e.ExceptionObject);

			// these 2 lines makes it graceful. sync (eg in main form's ctor) and thread exceptions will still crash us, but event (sync, void async, Task async) will not
			Application.ThreadException += (_, e) => MessageBoxLib.ShowAdminAlert(null, "Libation has encountered an unexpected error.", "Unexpected error", e.Exception);
			// move to beginning of execution. crashes app if this is called post-RunInstaller: System.InvalidOperationException: 'Thread exception mode cannot be changed once any Controls are created on the thread.'
			//// I never found a case where including made a difference. I think this enum is default and including it will override app user config file
			//Application.SetUnhandledExceptionMode(UnhandledExceptionMode.CatchException);
		}
	}
}