using System;
using System.Runtime.InteropServices;

namespace RobvanderWoude
{
	class IsRedirected
	{
		static int Main( string[] args )
		{
			try
			{
				bool chkInput = false;
				bool chkOutput = false;
				bool chkError = false;

				// Check command line arguments (/I, /O and/or /E switches allowed)
				switch ( args.Length )
				{
					case 0:
						chkInput = ConsoleEx.InputRedirected;
						chkOutput = ConsoleEx.OutputRedirected;
						chkError = ConsoleEx.ErrorRedirected;
						break;
					case 1:
						switch ( args[0].ToLower( ) )
						{
							case "/i":
							case "-i":
								chkInput = ConsoleEx.InputRedirected;
								break;
							case "/o":
							case "-o":
								chkOutput = ConsoleEx.OutputRedirected;
								break;
							case "/e":
							case "-e":
								chkError = ConsoleEx.ErrorRedirected;
								break;
							case "/?":
							case "-?":
							case "/h":
							case "-h":
							case "/help":
							case "-help":
								// Display help text without error message
								throw new Exception( string.Empty );
							default:
								throw new Exception( "Invalid command line argument" );
						}
						break;
					default:
						// Display help text with error message
						throw new Exception( "Invalid command line arguments" );
				}

				int result = 0;
				if ( chkInput )
				{
					result += 2;
				}
				if ( chkOutput )
				{
					result += 4;
				}
				if ( chkError )
				{
					result += 8;
				}

				// Pass through any redirected StdIn
				if ( ConsoleEx.InputRedirected )
				{
					string input = Console.In.ReadToEnd( );
					Console.Write( input );
				}
				
				// Return code 0..14 (even)
				return result;
			}
			catch ( Exception e )
			{
				// Display help text with error message
				return WriteError( e );
			}
		}

		// Code to detect redirection by Hans Passant on StackOverflow.com
		// http://stackoverflow.com/questions/3453220/how-to-detect-if-console-in-stdin-has-been-redirected
		public static class ConsoleEx
		{
			public static bool OutputRedirected
			{
				get
				{
					return FileType.Char != GetFileType( GetStdHandle( StdHandle.Stdout ) );
				}
			}
			public static bool InputRedirected
			{
				get
				{
					return FileType.Char != GetFileType( GetStdHandle( StdHandle.Stdin ) );
				}
			}
			public static bool ErrorRedirected
			{
				get
				{
					return FileType.Char != GetFileType( GetStdHandle( StdHandle.Stderr ) );
				}
			}

			// P/Invoke:
			private enum FileType { Unknown, Disk, Char, Pipe };
			private enum StdHandle { Stdin = -10, Stdout = -11, Stderr = -12 };

			[DllImport( "kernel32.dll" )]
			private static extern FileType GetFileType( IntPtr hdl );

			[DllImport( "kernel32.dll" )]
			private static extern IntPtr GetStdHandle( StdHandle std );
		}

		// Code to display help and optional error message, by Bas van der Woude
		public static int WriteError( Exception e )
		{
			return WriteError( e == null ? null : e.Message );
		}
		
		public static int WriteError( string errorMessage )
		{
			string fullpath = Environment.GetCommandLineArgs( ).GetValue( 0 ).ToString( );
			string[] program = fullpath.Split( '\\' );
			string exeName = program[program.GetUpperBound( 0 )];
			exeName = exeName.Substring( 0, exeName.IndexOf( '.' ) );

			Console.OpenStandardError( );
			if ( string.IsNullOrEmpty( errorMessage ) == false )
			{
				Console.WriteLine( );
				Console.ForegroundColor = ConsoleColor.Red;
				Console.Write( "ERROR: " );
				Console.ForegroundColor = ConsoleColor.White;
				Console.WriteLine( errorMessage );
				Console.ResetColor( );
			}

			Console.WriteLine( );
			Console.WriteLine( "IsRedirected,  Version 1.00" );
			Console.WriteLine( "Detect redirection of StdIn, StdOut and/or StdErr" );
			Console.WriteLine( "(Standard Input, Standard Output and Standard Error respectively)" );
			Console.WriteLine( );
			Console.Write( "Usage:  " );
			Console.ForegroundColor = ConsoleColor.White;
			Console.WriteLine( "{0}  [ /I | /O | /E ]", exeName.ToUpper( ) );
			Console.ResetColor( );
			Console.WriteLine( );
			Console.Write( "Where:  " );
			Console.ForegroundColor = ConsoleColor.White;
			Console.Write( "/I" );
			Console.ResetColor( );
			Console.Write( "   returns result for Std" );
			Console.ForegroundColor = ConsoleColor.White;
			Console.Write( "I" );
			Console.ResetColor( );
			Console.WriteLine( "n  redirection only (default: all)" );
			Console.ForegroundColor = ConsoleColor.White;
			Console.Write( "        /O" );
			Console.ResetColor( );
			Console.Write( "   returns result for Std" );
			Console.ForegroundColor = ConsoleColor.White;
			Console.Write( "O" );
			Console.ResetColor( );
			Console.WriteLine( "ut redirection only" );
			Console.ForegroundColor = ConsoleColor.White;
			Console.Write( "        /E" );
			Console.ResetColor( );
			Console.Write( "   returns result for Std" );
			Console.ForegroundColor = ConsoleColor.White;
			Console.Write( "E" );
			Console.ResetColor( );
			Console.WriteLine( "rr redirection only" );
			Console.WriteLine( );
			Console.WriteLine( "Note:   The result is returned as 'errorlevel', where" );
			Console.WriteLine( "        no redirection = 0, command line error = 1" );
			Console.WriteLine( "        redirected StdIn = +2, StdOut = +4, StdErr = +8" );
			Console.WriteLine( );
			Console.Write( "Check for redirection by Hans Passant on " );
			Console.ForegroundColor = ConsoleColor.DarkGray;
			Console.WriteLine( "StackOverflow.com" );
			Console.WriteLine( "/questions/3453220/how-to-detect-if-console-in-stdin-has-been-redirected" );
			Console.ResetColor( );
			Console.WriteLine( );
			Console.WriteLine( "Written by Rob van der Woude" );
			Console.WriteLine( "http://www.robvanderwoude.com" );
			Console.OpenStandardOutput( );
			return 1;
		}
	}
}