/* 
 * $Id$
 * Copyright 2008-2010 The Eraser Project
 * Original Author: Joel Low <lowjoel@users.sourceforge.net>
 * Modified By:
 * 
 * This file is part of Eraser.
 * 
 * Eraser is free software: you can redistribute it and/or modify it under the
 * terms of the GNU General Public License as published by the Free Software
 * Foundation, either version 3 of the License, or (at your option) any later
 * version.
 * 
 * Eraser is distributed in the hope that it will be useful, but WITHOUT ANY
 * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
 * A PARTICULAR PURPOSE. See the GNU General Public License for more details.
 * 
 * A copy of the GNU General Public License can be found at
 * <http://www.gnu.org/licenses/>.
 */

using System;
using System.Collections.Generic;
using System.Windows.Forms;

using System.IO;
using System.Threading;
using System.Globalization;
using System.ComponentModel;
using System.Runtime.Serialization;
using System.Security.Principal;
using System.Text.RegularExpressions;

using System.Reflection;
using System.Diagnostics;

using ComLib.Arguments;

using Eraser.Manager;
using Eraser.Util;
using File = System.IO.File;

namespace Eraser
{
	internal static partial class Program
	{
		/// <summary>
		/// The common program arguments shared between the GUI and console programs.
		/// </summary>
		class Arguments
		{
			/// <summary>
			/// True if the program should not be started with any user-visible interfaces.
			/// </summary>
			/// <remarks>Errors will also be silently ignored.</remarks>
			[Arg("quiet", "The program should not be started with any user-visible interfaces. " +
				"Errors will be silently ignored.", typeof(bool), false, false, null)]
			public bool Quiet { get; set; }
		}

		/// <summary>
		/// Program arguments which only apply to the GUI program.
		/// </summary>
		class GuiArguments : Arguments
		{
			/// <summary>
			/// True if the command line specified atRestart, which should result in the
			/// queueing of tasks meant for running at restart.
			/// </summary>
			[Arg("atRestart", "The program should queue all tasks scheduled for running at " +
				"the system restart.", typeof(bool), false, false, null)]
			public bool AtRestart { get; set; }
		}

		class ConsoleArguments : Arguments
		{
			/// <summary>
			/// The Action which this handler is in charge of.
			/// </summary>
			[Arg(0, "The action this command line is stating.", typeof(string), true, null, null)]
			public string Action { get; set; }

			/// <summary>
			/// The list of command line parameters not placed in a switch.
			/// </summary>
			public List<string> PositionalArguments { get; set; }
		}

		class AddTaskArguments : ConsoleArguments
		{
			/// <summary>
			/// The erasure method which the user specified on the command line.
			/// </summary>
			[Arg("method", "The erasure method to use", typeof(Guid), false, null, null)]
			public Guid ErasureMethod { get; set; }

			/// <summary>
			/// The schedule for the current set of targets.
			/// </summary>
			[Arg("schedule", "The schedule to use", typeof(Schedule), true, null, null)]
			public string Schedule { get; set; }
		}

		/// <summary>
		/// The main entry point for the application.
		/// </summary>
		[STAThread]
		static int Main(string[] commandLine)
		{
			//Immediately parse command line arguments
			ComLib.BoolMessageItem argumentParser = Args.Parse(commandLine,
				CommandLinePrefixes, CommandLineSeparators);
			Args parsedArguments = (Args)argumentParser.Item;

			//We default to a GUI if:
			// - The parser did not succeed.
			// - The parser resulted in an empty arguments list
			// - The parser's argument at index 0 is not equal to the first argument (this
			//   is when the user is passing GUI options -- command line options always
			//   start with the action, e.g. Eraser help, or Eraser addtask
			if (!argumentParser.Success || parsedArguments.IsEmpty ||
				parsedArguments.Positional[0] != parsedArguments.Raw[0])
			{
				GUIMain(commandLine);
			}
			else
			{
				return CommandMain(commandLine);
			}

			//Return zero to signify success
			return 0;
		}

		#region Console Program code
		/// <summary>
		/// Runs Eraser as a command-line application.
		/// </summary>
		/// <param name="commandLine">The command line parameters passed to Eraser.</param>
		private static int CommandMain(string[] commandLine)
		{
			using (ConsoleProgram program = new ConsoleProgram(commandLine))
			using (ManagerLibrary library = new ManagerLibrary(new Settings()))
				try
				{
					program.Handlers.Add("help",
						new ConsoleActionData(CommandHelp, new ConsoleArguments()));
					program.Handlers.Add("querymethods",
						new ConsoleActionData(CommandQueryMethods, new ConsoleArguments()));
					program.Handlers.Add("addtask",
						new ConsoleActionData(CommandAddTask, new AddTaskArguments()));
					program.Handlers.Add("importtasklist",
						new ConsoleActionData(CommandImportTaskList, new ConsoleArguments()));
					program.Run();
					return 0;
				}
				catch (UnauthorizedAccessException)
				{
					return 5; //ERROR_ACCESS_DENIED
				}
				catch (Win32Exception e)
				{
					Console.WriteLine(e.Message);
					return e.ErrorCode;
				}
				catch (Exception e)
				{
					Console.WriteLine(e.Message);
					return 1;
				}
		}

		/// <summary>
		/// Prints the command line help for Eraser.
		/// </summary>
		private static void PrintCommandHelp()
		{
			Console.WriteLine(@"usage: Eraser <action> <arguments>
where action is
    help                    Show this help message.
    addtask                 Adds tasks to the current task list.
    querymethods            Lists all registered Erasure methods.
	importtasklist          Imports an Eraser Task list to the curren user's Task List.

global parameters:
    --quiet, -q	            Do not create a Console window to display progress.

parameters for help:
    eraser help

    no parameters to set.

parameters for addtask:
    eraser addtask [--method=<methodGUID>] [--schedule=(now|manually|restart)] (recyclebin | unused=<volume> | dir=<directory> | file=<file>)[...]

    --method                The Erasure method to use.
    --schedule              The schedule the task will follow. The value must
                            be one of:
            now             The task will be queued for immediate execution.
            manually        The task will be created but not queued for execution.
            restart         The task will be queued for execution when the
                            computer is next restarted.
                            This parameter defaults to now.
    recyclebin              Erases files and folders in the recycle bin
    unused                  Erases unused space in the volume.
        optional arguments: unused=<drive>[,clusterTips[=(true|false)]]
            clusterTips     If specified, the drive's files will have their
                            cluster tips erased.
    dir                     Erases files and folders in the directory
        optional arguments: dir=<directory>[,-excludeMask][,+includeMask][,deleteIfEmpty]
            excludeMask     A wildcard expression for files and folders to
                            exclude.
            includeMask     A wildcard expression for files and folders to
                            include.
                            The include mask is applied before the exclude
                            mask.
            deleteIfEmpty   Deletes the folder at the end of the erasure if it
                            is empty.
    file                    Erases the specified file

parameters for querymethods:
    eraser querymethods

    no parameters to set.

parameters for importtasklist:
    eraser importtasklist (file)[...]

    [file]                  A list of one or more files to import.

All arguments are case sensitive.");
			Console.Out.Flush();
		}

		/// <summary>
		/// Prints the help text for Eraser (with copyright)
		/// </summary>
		/// <param name="arguments">Not used.</param>
		private static void CommandHelp(ConsoleArguments arguments)
		{
			Console.WriteLine(@"Eraser {0}
(c) 2008-2010 The Eraser Project
Eraser is Open-Source Software: see http://eraser.heidi.ie/ for details.
", Assembly.GetExecutingAssembly().GetName().Version);

			PrintCommandHelp();
		}

		/// <summary>
		/// Lists all registered erasure methods.
		/// </summary>
		/// <param name="arguments">Not used.</param>
		private static void CommandQueryMethods(ConsoleArguments arguments)
		{
			//Output the header
			const string methodFormat = "{0,-2} {1,-39} {2}";
			Console.WriteLine(methodFormat, "", "Method", "GUID");
			Console.WriteLine(new string('-', 79));

			//Refresh the list of erasure methods
			Dictionary<Guid, ErasureMethod> methods = ErasureMethodManager.Items;
			foreach (ErasureMethod method in methods.Values)
			{
				Console.WriteLine(methodFormat, (method is UnusedSpaceErasureMethod) ?
					"U" : "", method.Name, method.Guid.ToString());
			}
		}

		/// <summary>
		/// Parses the command line for tasks and adds them using the
		/// <see cref="RemoteExecutor"/> class.
		/// </summary>
		/// <param name="arg">The command line parameters passed to the program.</param>
		private static void CommandAddTask(ConsoleArguments arg)
		{
			AddTaskArguments arguments = (AddTaskArguments)arg;

			//Create the task then set the method as well as schedule
			Task task = new Task();
			ErasureMethod method = arguments.ErasureMethod == Guid.Empty ?
				ErasureMethodManager.Default :
				ErasureMethodManager.GetInstance(arguments.ErasureMethod);
			switch (arguments.Schedule.ToLowerInvariant())
			{
				case "now":
					task.Schedule = Schedule.RunNow;
					break;
				case "manually":
					task.Schedule = Schedule.RunManually;
					break;
				case "restart":
					task.Schedule = Schedule.RunOnRestart;
					break;
				default:
					throw new ArgumentException(string.Format(
						"Unknown schedule type: {0}", arguments.Schedule), "--schedule");
			}

			//Parse the rest of the command line parameters as target expressions.
			List<string> trueValues = new List<string>(new string[] { "yes", "true" });
			string[] strings = new string[] {
				//The recycle bin target
				"(?<recycleBin>recyclebin)",

				//The unused space erasure target, taking the optional clusterTips
				//argument which defaults to true; if none is specified it's assumed
				//false
				"unused=(?<unusedVolume>.*)(?<unusedTips>,clusterTips(=(?<unusedTipsValue>true|false))?)?",

				//The directory target, taking a list of + and - wildcard expressions.
				"dir=(?<directoryName>.*)(?<directoryParams>(?<directoryExcludeMask>,-[^,]+)|(?<directoryIncludeMask>,\\+[^,]+)|(?<directoryDeleteIfEmpty>,deleteIfEmpty(=(?<directoryDeleteIfEmptyValue>true|false))?))*",

				//The file target.
				"file=(?<fileName>.*)"
			};

			Regex regex = new Regex(string.Join("|", strings),
				RegexOptions.Compiled | RegexOptions.IgnoreCase | RegexOptions.RightToLeft);
			foreach (string argument in arguments.PositionalArguments)
			{
				Match match = regex.Match(argument);
				if (match.Captures.Count == 0)
				{
					Console.WriteLine("Unknown argument: {0}, skipped.", argument);
					continue;
				}

				ErasureTarget target = null;
				if (match.Groups["recycleBin"].Success)
				{
					target = new RecycleBinTarget();
				}
				else if (match.Groups["unusedVolume"].Success)
				{
					UnusedSpaceTarget unusedSpaceTarget = new UnusedSpaceTarget();
					target = unusedSpaceTarget;
					unusedSpaceTarget.Drive = match.Groups["unusedVolume"].Value;

					if (!match.Groups["unusedTips"].Success)
						unusedSpaceTarget.EraseClusterTips = false;
					else if (!match.Groups["unusedTipsValue"].Success)
						unusedSpaceTarget.EraseClusterTips = true;
					else
						unusedSpaceTarget.EraseClusterTips =
							trueValues.IndexOf(match.Groups["unusedTipsValue"].Value) != -1;
				}
				else if (match.Groups["directoryName"].Success)
				{
					FolderTarget folderTarget = new FolderTarget();
					target = folderTarget;

					folderTarget.Path = match.Groups["directoryName"].Value;
					if (!match.Groups["directoryDeleteIfEmpty"].Success)
						folderTarget.DeleteIfEmpty = false;
					else if (!match.Groups["directoryDeleteIfEmptyValue"].Success)
						folderTarget.DeleteIfEmpty = true;
					else
						folderTarget.DeleteIfEmpty =
							trueValues.IndexOf(match.Groups["directoryDeleteIfEmptyValue"].Value) != -1;
					if (match.Groups["directoryExcludeMask"].Success)
						folderTarget.ExcludeMask += match.Groups["directoryExcludeMask"].Value.Remove(0, 2) + ' ';
					if (match.Groups["directoryIncludeMask"].Success)
						folderTarget.IncludeMask += match.Groups["directoryIncludeMask"].Value.Remove(0, 2) + ' ';
				}
				else if (match.Groups["fileName"].Success)
				{
					FileTarget fileTarget = new FileTarget();
					target = fileTarget;
					fileTarget.Path = match.Groups["fileName"].Value;
				}

				if (target == null)
					continue;

				target.Method = method;
				task.Targets.Add(target);
			}

			//Check the number of tasks in the task.
			if (task.Targets.Count == 0)
				throw new ArgumentException("Tasks must contain at least one erasure target.");

			//Send the task out.
			try
			{
				using (RemoteExecutorClient client = new RemoteExecutorClient())
				{
					client.Run();
					if (!client.IsConnected)
					{
						//The client cannot connect to the server. This probably means
						//that the server process isn't running. Start an instance.
						Process eraserInstance = Process.Start(
							Assembly.GetExecutingAssembly().Location, "--quiet");
						eraserInstance.WaitForInputIdle();

						client.Run();
						if (!client.IsConnected)
							throw new IOException("Eraser cannot connect to the running " +
								"instance for erasures.");
					}

					client.Tasks.Add(task);
				}
			}
			catch (UnauthorizedAccessException e)
			{
				//We can't connect to the pipe because the other instance of Eraser
				//is running with higher privileges than this instance.
				throw new UnauthorizedAccessException("Another instance of Eraser " +
					"is already running but it is running with higher privileges than " +
					"this instance of Eraser. Tasks cannot be added in this manner.\n\n" +
					"Close the running instance of Eraser and start it again without " +
					"administrator privileges, or run the command again as an " +
					"administrator.", e);
			}
		}

		/// <summary>
		/// Imports the given tasklists and adds them to the global Eraser instance.
		/// </summary>
		/// <param name="args">The list of files specified on the command line.</param>
		private static void CommandImportTaskList(ConsoleArguments args)
		{
			//Import the task list
			try
			{
				using (RemoteExecutorClient client = new RemoteExecutorClient())
				{
					client.Run();
					if (!client.IsConnected)
					{
						//The client cannot connect to the server. This probably means
						//that the server process isn't running. Start an instance.
						Process eraserInstance = Process.Start(
							Assembly.GetExecutingAssembly().Location, "--quiet");
						eraserInstance.WaitForInputIdle();

						client.Run();
						if (!client.IsConnected)
							throw new IOException("Eraser cannot connect to the running " +
								"instance for erasures.");
					}

					foreach (string path in args.PositionalArguments)
						using (FileStream stream = new FileStream(path, FileMode.Open, FileAccess.Read))
							client.Tasks.LoadFromStream(stream);
				}
			}
			catch (UnauthorizedAccessException e)
			{
				//We can't connect to the pipe because the other instance of Eraser
				//is running with higher privileges than this instance.
				throw new UnauthorizedAccessException("Another instance of Eraser " +
					"is already running but it is running with higher privileges than " +
					"this instance of Eraser. Tasks cannot be added in this manner.\n\n" +
					"Close the running instance of Eraser and start it again without " +
					"administrator privileges, or run the command again as an " +
					"administrator.", e);
			}
		}
		#endregion

		#region GUI Program code
		/// <summary>
		/// Runs Eraser as a GUI application.
		/// </summary>
		/// <param name="commandLine">The command line parameters passed to Eraser.</param>
		private static void GUIMain(string[] commandLine)
		{
			//Create a unique program instance ID for this user.
			string instanceId = "Eraser-BAD0DAC6-C9EE-4acc-8701-C9B3C64BC65E-GUI-" +
				WindowsIdentity.GetCurrent().User.ToString();

			//Then initialise the instance and initialise the Manager library.
			using (GuiProgram program = new GuiProgram(commandLine, instanceId))
			using (ManagerLibrary library = new ManagerLibrary(new Settings()))
			{
				program.InitInstance += OnGUIInitInstance;
				program.NextInstance += OnGUINextInstance;
				program.ExitInstance += OnGUIExitInstance;
				program.Run();
			}
		}

		/// <summary>
		/// Triggered when the Program is started for the first time.
		/// </summary>
		/// <param name="sender">The sender of the object.</param>
		/// <param name="e">Event arguments.</param>
		private static void OnGUIInitInstance(object sender, InitInstanceEventArgs e)
		{
			GuiProgram program = (GuiProgram)sender;
			eraserClient = new RemoteExecutorServer();

			//Set our UI language
			EraserSettings settings = EraserSettings.Get();
			Thread.CurrentThread.CurrentUICulture = new CultureInfo(settings.Language);
			Application.SafeTopLevelCaptionFormat = S._("Eraser");

			//Load the task list
			SettingsCompatibility.Execute();
			try
			{
				if (File.Exists(TaskListPath))
				{
					using (FileStream stream = new FileStream(TaskListPath, FileMode.Open,
						FileAccess.Read, FileShare.Read))
					{
						eraserClient.Tasks.LoadFromStream(stream);
					}
				}
			}
			catch (SerializationException ex)
			{
				System.IO.File.Delete(TaskListPath);
				MessageBox.Show(S._("Could not load task list. All task entries have " +
					"been lost. The error returned was: {0}", ex.Message), S._("Eraser"),
					MessageBoxButtons.OK, MessageBoxIcon.Error,
					MessageBoxDefaultButton.Button1,
					S.IsRightToLeft(null) ? MessageBoxOptions.RtlReading : 0);
			}

			//Create the main form
			program.MainForm = new MainForm();

			//Decide whether to display any UI
			GuiArguments arguments = new GuiArguments();
			Args.Parse(program.CommandLine, CommandLinePrefixes, CommandLineSeparators, arguments);
			e.ShowMainForm = !arguments.AtRestart && !arguments.Quiet;

			//Queue tasks meant for running at restart if we are given that command line.
			if (arguments.AtRestart)
				eraserClient.QueueRestartTasks();

			//Run the eraser client.
			eraserClient.Run();
		}

		/// <summary>
		/// Triggered when a second instance of Eraser is started.
		/// </summary>
		/// <param name="sender">The sender of the event.</param>
		/// <param name="e">Event argument.</param>
		private static void OnGUINextInstance(object sender, NextInstanceEventArgs e)
		{
			//Another instance of the GUI Program has been started: show the main window
			//now as we still do not have a facility to handle the command line arguments.
			GuiProgram program = (GuiProgram)sender;

			//Invoke the function if we aren't on the main thread
			if (program.MainForm.InvokeRequired)
			{
				program.MainForm.Invoke(
					(GuiProgram.NextInstanceEventHandler)OnGUINextInstance,
					sender, e);
				return;
			}

			program.MainForm.Show();
		}

		/// <summary>
		/// Triggered when the first instance of Eraser is exited.
		/// </summary>
		/// <param name="sender">The sender of the event.</param>
		/// <param name="e">Event argument.</param>
		private static void OnGUIExitInstance(object sender, EventArgs e)
		{
			//Save the task list
			if (!Directory.Exists(Program.AppDataPath))
				Directory.CreateDirectory(Program.AppDataPath);
			using (FileStream stream = new FileStream(TaskListPath, FileMode.Create,
				FileAccess.Write, FileShare.None))
			{
				eraserClient.Tasks.SaveToStream(stream);
			}

			//Dispose the eraser executor instance
			eraserClient.Dispose();
		}
		#endregion

		/// <summary>
		/// The acceptable list of command line prefixes we will accept.
		/// </summary>
		public const string CommandLinePrefixes = "(/|-|--)";

		/// <summary>
		/// The acceptable list of command line separators we will accept.
		/// </summary>
		public const string CommandLineSeparators = "(:|=)";

		/// <summary>
		/// The global Executor instance.
		/// </summary>
		public static Executor eraserClient;

		/// <summary>
		/// Path to the Eraser application data path.
		/// </summary>
		public static readonly string AppDataPath = Path.Combine(Environment.GetFolderPath(
			Environment.SpecialFolder.LocalApplicationData), @"Eraser 6");

		/// <summary>
		/// File name of the Eraser task list.
		/// </summary>
		private const string TaskListFileName = @"Task List.ersx";

		/// <summary>
		/// Path to the Eraser task list.
		/// </summary>
		public static readonly string TaskListPath = Path.Combine(AppDataPath, TaskListFileName);

		/// <summary>
		/// Path to the Eraser settings key (relative to HKCU)
		/// </summary>
		public const string SettingsPath = @"SOFTWARE\Eraser\Eraser 6";
	}
}