/*
 * Copyright (c) 2018 ETH Zürich, Educational Development and Technology (LET)
 * 
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 */

using System;
using SafeExamBrowser.Contracts.Behaviour;
using SafeExamBrowser.Contracts.Behaviour.Operations;
using SafeExamBrowser.Contracts.Communication;
using SafeExamBrowser.Contracts.Configuration;
using SafeExamBrowser.Contracts.Configuration.Settings;
using SafeExamBrowser.Contracts.Logging;
using SafeExamBrowser.Contracts.Monitoring;
using SafeExamBrowser.Contracts.UserInterface;
using SafeExamBrowser.Contracts.UserInterface.Taskbar;

namespace SafeExamBrowser.Client.Behaviour
{
	internal class ClientController : IClientController
	{
		private IDisplayMonitor displayMonitor;
		private ILogger logger;
		private IOperationSequence operations;
		private IProcessMonitor processMonitor;
		private IRuntimeProxy runtime;
		private Action shutdown;
		private ISplashScreen splashScreen;
		private ITaskbar taskbar;
		private IUserInterfaceFactory uiFactory;
		private IWindowMonitor windowMonitor;
		private RuntimeInfo runtimeInfo;

		public IClientHost ClientHost { private get; set; }
		public Guid SessionId { private get; set; }
		public Settings Settings { private get; set; }

		public RuntimeInfo RuntimeInfo
		{
			set
			{
				runtimeInfo = value;

				if (splashScreen != null)
				{
					splashScreen.RuntimeInfo = value;
				}
			}
		}

		public ClientController(
			IDisplayMonitor displayMonitor,
			ILogger logger,
			IOperationSequence operations,
			IProcessMonitor processMonitor,
			IRuntimeProxy runtime,
			Action shutdown,
			ITaskbar taskbar,
			IUserInterfaceFactory uiFactory,
			IWindowMonitor windowMonitor)
		{
			this.displayMonitor = displayMonitor;
			this.logger = logger;
			this.operations = operations;
			this.processMonitor = processMonitor;
			this.runtime = runtime;
			this.shutdown = shutdown;
			this.taskbar = taskbar;
			this.uiFactory = uiFactory;
			this.windowMonitor = windowMonitor;
		}

		public bool TryStart()
		{
			logger.Info("--- Initiating startup procedure ---");

			splashScreen = uiFactory.CreateSplashScreen();
			operations.ProgressIndicator = splashScreen;

			var success = operations.TryPerform();

			// TODO

			if (success)
			{
				RegisterEvents();
				// TODO: Handle communication exception!
				runtime.InformClientReady();
				splashScreen.Hide();

				logger.Info("--- Application successfully initialized ---");
				logger.Log(string.Empty);
			}
			else
			{
				logger.Info("--- Application startup aborted! ---");
				logger.Log(string.Empty);
			}

			return success;
		}

		public void Terminate()
		{
			logger.Log(string.Empty);
			logger.Info("--- Initiating shutdown procedure ---");

			splashScreen.Show();
			splashScreen.BringToForeground();

			// TODO

			DeregisterEvents();
			var success = operations.TryRevert();

			if (success)
			{
				logger.Info("--- Application successfully finalized ---");
				logger.Log(string.Empty);
			}
			else
			{
				logger.Info("--- Shutdown procedure failed! ---");
				logger.Log(string.Empty);
			}

			splashScreen?.Close();
		}

		private void RegisterEvents()
		{
			ClientHost.Shutdown += ClientHost_Shutdown;
			displayMonitor.DisplayChanged += DisplayMonitor_DisplaySettingsChanged;
			processMonitor.ExplorerStarted += ProcessMonitor_ExplorerStarted;
			taskbar.QuitButtonClicked += Taskbar_QuitButtonClicked;
			windowMonitor.WindowChanged += WindowMonitor_WindowChanged;
		}

		private void DeregisterEvents()
		{
			ClientHost.Shutdown -= ClientHost_Shutdown;
			displayMonitor.DisplayChanged -= DisplayMonitor_DisplaySettingsChanged;
			processMonitor.ExplorerStarted -= ProcessMonitor_ExplorerStarted;
			taskbar.QuitButtonClicked -= Taskbar_QuitButtonClicked;
			windowMonitor.WindowChanged -= WindowMonitor_WindowChanged;
		}

		private void DisplayMonitor_DisplaySettingsChanged()
		{
			logger.Info("Reinitializing working area...");
			displayMonitor.InitializePrimaryDisplay(taskbar.GetAbsoluteHeight());
			logger.Info("Reinitializing taskbar bounds...");
			taskbar.InitializeBounds();
			logger.Info("Desktop successfully restored.");
		}

		private void ProcessMonitor_ExplorerStarted()
		{
			logger.Info("Trying to shut down explorer...");
			processMonitor.CloseExplorerShell();
			logger.Info("Reinitializing working area...");
			displayMonitor.InitializePrimaryDisplay(taskbar.GetAbsoluteHeight());
			logger.Info("Reinitializing taskbar bounds...");
			taskbar.InitializeBounds();
			logger.Info("Desktop successfully restored.");
		}

		private void ClientHost_Shutdown()
		{
			taskbar.Close();
			shutdown.Invoke();
		}

		private void Taskbar_QuitButtonClicked()
		{
			// TODO: MessageBox asking whether user really wants to quit -> only then request shutdown!
			// TODO: Handle communication exception!
			runtime.RequestShutdown();
		}

		private void WindowMonitor_WindowChanged(IntPtr window)
		{
			var allowed = processMonitor.BelongsToAllowedProcess(window);

			if (!allowed)
			{
				var success = windowMonitor.Hide(window);

				if (!success)
				{
					windowMonitor.Close(window);
				}
			}
		}
	}
}