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

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();

		[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();

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

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

			var form1 = new Form1();
			form1.Load += async (_, _) => await form1.InitLibraryAsync(await libraryLoadTask);
			LibationUiBase.Forms.MessageBoxBase.ShowAsyncImpl = ShowMessageBox;
			Application.Run(form1);

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

				return Task.FromResult((LibationUiBase.Forms.DialogResult)result);
			}
			#endregion;
		}

		private static void RunInstaller(Configuration config)
		{
			// all returns should be preceded by either:
			// - if config.LibationSettingsAreValid
			// - error message, Exit()

			if (config.LibationSettingsAreValid)
				return;

			var defaultLibationFilesDir = Configuration.DefaultLibationFilesDirectory;

			// check for existing settings in default location
			var defaultSettingsFile = Path.Combine(defaultLibationFilesDir, "Settings.json");
			if (Configuration.SettingsFileIsValid(defaultSettingsFile))
				Configuration.SetLibationFiles(defaultLibationFilesDir);

			if (config.LibationSettingsAreValid)
				return;

			static void CancelInstallation()
			{
				MessageBox.Show("Initial set up cancelled.", "Cancelled", MessageBoxButtons.OK, MessageBoxIcon.Warning);
				Application.Exit();
				Environment.Exit(0);
			}

			var setupDialog = new SetupDialog();
			if (setupDialog.ShowDialog() != DialogResult.OK)
			{
				CancelInstallation();
				return;
			}

			if (setupDialog.IsNewUser)
				Configuration.SetLibationFiles(defaultLibationFilesDir);
			else if (setupDialog.IsReturningUser)
			{
				var libationFilesDialog = new LibationFilesDialog();

				if (libationFilesDialog.ShowDialog() != DialogResult.OK)
				{
					CancelInstallation();
					return;
				}

				Configuration.SetLibationFiles(libationFilesDialog.SelectedDirectory);
				if (config.LibationSettingsAreValid)
					return;

				// path did not result in valid settings
				var continueResult = MessageBox.Show(
					$"No valid settings were found at this location.\r\nWould you like to create a new install settings in this folder?\r\n\r\n{libationFilesDialog.SelectedDirectory}",
					"New install?",
					MessageBoxButtons.YesNo,
					MessageBoxIcon.Question);

				if (continueResult != DialogResult.Yes)
				{
					CancelInstallation();
					return;
				}
			}

			// INIT DEFAULT SETTINGS
			// if 'new user' was clicked, or if 'returning user' chose new install: show basic settings dialog
			config.Books ??= Configuration.DefaultBooksDirectory;

			if (config.LibationSettingsAreValid)
				return;

			CancelInstallation();
		}

		/// <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);
		}
	}
}