using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Runtime.InteropServices;
using System.Text;


namespace RobvanderWoude
{
	class ActivateWindow
	{
		static readonly string progver = "1.03";


		static bool debug = false;
		static bool exactmatch = false;
		static List<string> windowtitles = new List<string>( );
		static string exact = "partial ";
		static string matchingtitle = string.Empty;
		static string progname = string.Empty;
		static string windowtitle = string.Empty;


		static int Main( string[] args )
		{
			bool querycurrent = false;
			bool useprogname = false;


			#region Parse and Validate Command Line

			if ( args.Length == 0 )
			{
				return ShowHelp( );
			}

			foreach ( string arg in args )
			{
				if ( arg[0] == '/' )
				{
					switch ( arg.ToUpper( ) )
					{
						case "/?":
							return ShowHelp( );
						case "/C":
							if ( querycurrent )
							{
								return ShowHelp( "Duplicate switch /C" );
							}
							querycurrent = true;
							break;
						case "/D":
							if ( useprogname )
							{
								return ShowHelp( "Switches /P and /D are mutually exclusive" );
							}
							if ( debug )
							{
								return ShowHelp( "Duplicate switch /D" );
							}
							debug = true;
							break;
						case "/P":
							if ( debug )
							{
								return ShowHelp( "Switches /P and /D are mutually exclusive" );
							}
							if ( useprogname )
							{
								return ShowHelp( "Duplicate switch /P" );
							}
							useprogname = true;
							break;
						case "/X":
							if ( exactmatch )
							{
								return ShowHelp( "Duplicate switch /X" );
							}
							exactmatch = true;
							exact = "exact ";
							break;
						default:
								return ShowHelp( "Invalid switch \"{0}\"", arg );
					}
				}
				else
				{
					if ( !windowtitles.Contains( arg ) )
					{
						windowtitles.Add( arg );
					}
				}
			}

			if ( useprogname )
			{
				if ( exactmatch )
				{
					return ShowHelp( "Switches /P and /X are mutually exclusive" );
				}
				if ( windowtitles.Count == 1 )
				{
					progname = windowtitles[0];
				}
				else
				{
					return ShowHelp( "Specifie a single program executable when using /P switch" );
				}
			}

			if ( querycurrent && args.Length > 1 )
			{
				return ShowHelp( "/C switch cannot be combined with other command line arguments" );
			}



#if DEBUG
			debug = true;
#endif


			#endregion Parse and validate Command Line


			if ( querycurrent )
			{
				return QueryActive( );
			}
			else if ( useprogname )
			{
				return ActivateByProgName( );
			}
			else
			{
				return ActivateByTitle( );
			}
		}


		static int ActivateByProgName( )
		{
			// Based on code by Hans Passant on StackOverflow.com
			// https://stackoverflow.com/a/2819747
			Process[] proc = Process.GetProcessesByName( progname ); // progname should be WITHOUT extension
			if ( proc.Length > 0 )
			{
				SetForegroundWindow( proc[0].MainWindowHandle ); // Make first match the foreground window
			}
			else
			{
				proc = Process.GetProcessesByName( Path.GetFileNameWithoutExtension( progname ) ); // try stripping extension
				if ( proc.Length > 0 )
				{
					SetForegroundWindow( proc[0].MainWindowHandle ); // Make first match the foreground window
				}
				else
				{
					Console.Error.WriteLine( "No process with specified name \"{0}\" was found.", progname );
					return 1;
				}
			}
			return 0;
		}


		static int ActivateByTitle( )
		{
			// Find the window with the specified title
			IntPtr handle = FindWindow( windowtitles, exactmatch );
			if ( handle == IntPtr.Zero )
			{
				Console.Error.WriteLine( "No window was found with {0}title.", exact );
				return 1;
			}
			else
			{
				if ( debug && !exactmatch )
				{
					Console.WriteLine( "Specified title : \"{0}\"\nMatching title  : \"{1}\"\n", windowtitle, matchingtitle );
				}
				// If found, make it the foreground window
				if ( !SetForegroundWindow( handle ) )
				{
					Console.Error.WriteLine( "Unable to move the specified window to the foreground." );
					return -1;
				}
			}
			return 0;
		}


		static IntPtr FindWindow( List<string> titles, bool exacttitlematch = false )
		{
			foreach ( Process process in Process.GetProcesses( ) )
			{
				foreach( string title in titles )
				{
					if ( process.MainWindowTitle.Equals( title, StringComparison.InvariantCultureIgnoreCase ) )
					{
						return process.MainWindowHandle; // Return the FIRST matching window
					}
					else if ( !exacttitlematch )
					{

						if ( process.MainWindowTitle.ToUpper( ).Contains( title.ToUpper( ) ) )
						{
							matchingtitle = process.MainWindowTitle;
							windowtitle = title;
							return process.MainWindowHandle; // Return the FIRST matching window
						}
					}
				}
			}
			return IntPtr.Zero; // In case no matching title was found
		}


		static string GetActiveWindowTitle( )
		{
			// Code by Jorge Ferreira on StackOverflow.com
			// https://stackoverflow.com/a/115905
			const int nChars = 256;
			StringBuilder Buff = new StringBuilder( nChars );
			IntPtr handle = GetForegroundWindow( );

			if ( GetWindowText( handle, Buff, nChars ) > 0 )
			{
				return Buff.ToString( );
			}
			return null;
		}


		static int QueryActive( )
		{
			// Find the title of the currently active window
			string activewindowtitle = GetActiveWindowTitle( );
			if ( string.IsNullOrWhiteSpace( activewindowtitle ) )
			{
				Console.Error.WriteLine( "Unable to query the active window's title." );
				return -1;
			}
			else
			{
				Console.WriteLine( activewindowtitle );
				return 0;
			}
		}


		#region DLL Imports

		[DllImport( "user32.dll" )]
		[return: MarshalAs( UnmanagedType.Bool )]
		static extern bool SetForegroundWindow( IntPtr hWnd );


		[DllImport( "user32.dll" )]
		static extern IntPtr GetForegroundWindow( );


		[DllImport( "user32.dll" )]
		static extern int GetWindowText( IntPtr hWnd, StringBuilder text, int count );

		#endregion DLL Imports


		#region Error handling

		static int ShowHelp( params string[] errmsg )
		{
			#region Error Message

			if ( errmsg.Length > 0 )
			{
				List<string> errargs = new List<string>( errmsg );
				errargs.RemoveAt( 0 );
				Console.Error.WriteLine( );
				Console.ForegroundColor = ConsoleColor.Red;
				Console.Error.Write( "ERROR:\t" );
				Console.ForegroundColor = ConsoleColor.White;
				Console.Error.WriteLine( errmsg[0], errargs.ToArray( ) );
				Console.ResetColor( );
			}

			#endregion Error Message


			#region Help Text

			/*
			ActivateWindow.exe,  Version 1.03
			Activate the specified window

			Usage:   ActivateWindow.exe  title  [ title  [ title ... ] ]  [ /D ]  [ /X ]

			   or:   ActivateWindow.exe  progname  /P

			   or:   ActivateWindow.exe  /C

			Where:   title     is a (partial) title of the window to be activated
			                   (first matching title is used)
			         progname  is the executable name of the window to be activated
			                   (name only, no extension)

			Options: /C        show Currently active window's title on screen
			         /D        Debug mode: show match used for partial title
			         /P        specified name is Program executable name
			                   (default: specified name is window title)
			         /X        window title and specified title must match eXactly
			                   (default: window title contains specified title)

			Notes:   With /P switch, if no match is found, the program will try and
			         strip an extension from progname if applicable, and search again.
			         Return code 0 on success, 1 if no match, or -1 in case of errors.

			Written by Rob van der Woude
			https://www.robvanderwoude.com
			*/

			#endregion Help Text


			#region Display Help Text

			Console.Error.WriteLine( );

			Console.Error.WriteLine( "ActivateWindow.exe,  Version {0}", progver );

			Console.Error.WriteLine( "Activate the specified window" );

			Console.Error.WriteLine( );

			Console.Error.Write( "Usage:   " );
			Console.ForegroundColor = ConsoleColor.White;
			Console.Error.WriteLine( "ActivateWindow.exe  title  [ title  [ title ... ] ]  [ /D ]  [ /X ]" );
			Console.ResetColor( );

			Console.Error.WriteLine( );

			Console.Error.Write( "   or:   " );
			Console.ForegroundColor = ConsoleColor.White;
			Console.Error.WriteLine( "ActivateWindow.exe  progname  /P" );
			Console.ResetColor( );

			Console.Error.WriteLine( );

			Console.Error.Write( "   or:   " );
			Console.ForegroundColor = ConsoleColor.White;
			Console.Error.WriteLine( "ActivateWindow.exe  /C" );
			Console.ResetColor( );

			Console.Error.WriteLine( );

			Console.Write( "Where:   " );
			Console.ForegroundColor = ConsoleColor.White;
			Console.Write( "title     " );
			Console.ResetColor( );
			Console.WriteLine( "is a (partial) title of the window to be activated" );

			Console.Error.WriteLine( "                   (first matching title is used)" );

			Console.Error.WriteLine( );

			Console.ForegroundColor = ConsoleColor.White;
			Console.Error.Write( "         progname  " );
			Console.ResetColor( );
			Console.Error.Write( "is the executable " );
			Console.ForegroundColor = ConsoleColor.White;
			Console.Error.Write( "name" );
			Console.ResetColor( );
			Console.Error.WriteLine( " of the window to be activated" );

			Console.Error.WriteLine( "                   (name only, no extension)" );

			Console.Error.WriteLine( );

			Console.Error.Write( "Options: " );
			Console.ForegroundColor = ConsoleColor.White;
			Console.Error.Write( "/C        " );
			Console.ResetColor( );
			Console.Error.Write( "show " );
			Console.ForegroundColor = ConsoleColor.White;
			Console.Error.Write( "C" );
			Console.ResetColor( );
			Console.Error.WriteLine( "urrently active window's title on screen" );


			Console.ForegroundColor = ConsoleColor.White;
			Console.Error.Write( "         /D        D" );
			Console.ResetColor( );
			Console.Error.WriteLine( "ebug mode: show match used for partial title" );

			Console.ForegroundColor = ConsoleColor.White;
			Console.Error.Write( "         /P" );
			Console.ResetColor( );
			Console.Error.Write( "        specified name is " );
			Console.ForegroundColor = ConsoleColor.White;
			Console.Error.Write( "P" );
			Console.ResetColor( );
			Console.Error.WriteLine( "rogram executable name" );

			Console.Error.WriteLine( "                   (default: specified name is window title)" );

			Console.ForegroundColor = ConsoleColor.White;
			Console.Error.Write( "         /X        " );
			Console.ResetColor( );
			Console.Error.Write( "window title and specified title must match e" );
			Console.ForegroundColor = ConsoleColor.White;
			Console.Error.Write( "X" );
			Console.ResetColor( );
			Console.Error.WriteLine( "actly" );

			Console.Error.Write( "                   (default: window title " );
			Console.ForegroundColor = ConsoleColor.White;
			Console.Error.Write( "contains " );
			Console.ResetColor( );
			Console.Error.WriteLine( "specified title)" );

			Console.Error.WriteLine( );

			Console.Error.Write( "Notes:   With " );
			Console.ForegroundColor = ConsoleColor.White;
			Console.Error.Write( "/P" );
			Console.ResetColor( );
			Console.Error.WriteLine( " switch, if no match is found, the program will try and" );

			Console.Error.Write( "         strip an extension from " );
			Console.ForegroundColor = ConsoleColor.White;
			Console.Error.Write( "progname" );
			Console.ResetColor( );
			Console.Error.WriteLine( " if applicable, and search again." );

			Console.Error.WriteLine( "         Return code 0 on success, 1 if no match, or -1 in case of errors." );

			Console.Error.WriteLine( );

			Console.Error.WriteLine( "Written by Rob van der Woude" );

			Console.Error.WriteLine( "https://www.robvanderwoude.com" );

			#endregion Display Help Text


			return -1;
		}

		#endregion Error handling
	}
}