using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Windows.Forms;


namespace RobvanderWoude
{
	internal class Rtf2Txt
	{
		static string progver = "1.00";


		static int Main( string[] args )
		{
			Encoding encoding = null;

			if ( args.Length == 0 || args.Length > 2 || args.Contains( "/?" ) )
			{
				return ShowHelp( );
			}
			
			if ( args.Contains( "/E", StringComparer.OrdinalIgnoreCase ) )
			{
				return ListEncodings( );
			}
			
			string file = args[0];

			if ( args.Length == 2 )
			{
				encoding = GetEncoding( args[1] );
			}

			if ( File.Exists( file ) && Path.GetExtension( file ).ToLower( ) == ".rtf" )
			{
				// Use a hidden RichTextBox to convert RTF to plain text, by Wendy Zang
				// https://social.msdn.microsoft.com/Forums/vstudio/en-US/6e56af9b-d7d3-49f3-9ec4-80edde3fe54b/reading-modifying-rtf-files?forum=csharpgeneral#a64345e9-cfcb-43be-ab18-c08fae02cb2a
				RichTextBox rtbox = new RichTextBox( );
				string rtftext = File.ReadAllText( file );
				rtbox.Rtf = rtftext;
				string plaintext = rtbox.Text;

				if ( encoding == null )
				{
					Console.WriteLine( plaintext );
				}
				else
				{
					Encoding oldencoding = Console.OutputEncoding;
					Console.OutputEncoding = encoding;
					Console.WriteLine( plaintext );
					Console.OutputEncoding = oldencoding;
				}

				return 0;
			}

			return ShowHelp( );
		}


		static Encoding GetEncoding( string myencoding )
		{
			if ( string.IsNullOrEmpty( myencoding ) )
			{
				return null;
			}
			// Get a list of available encodings
			EncodingInfo[] encodings = Encoding.GetEncodings( );
			// Try correctly spelled encodings first
			foreach ( EncodingInfo encoding in encodings )
			{
				if ( encoding.Name.ToLower( ) == myencoding.ToLower( ) )
				{
					return Encoding.GetEncoding( encoding.CodePage );
				}
			}
			// No direct match found, try again, ignoring dashes
			foreach ( EncodingInfo encoding in encodings )
			{
				if ( encoding.Name.Replace( "-", "" ).ToLower( ) == myencoding.Replace( "-", "" ).ToLower( ) )
				{
					return Encoding.GetEncoding( encoding.CodePage );
				}
			}
			// Still no match, try codepages
			foreach ( EncodingInfo encoding in encodings )
			{
				if ( encoding.CodePage.ToString( ) == myencoding )
				{
					return Encoding.GetEncoding( encoding.CodePage );
				}
			}
			// Still no match, giving up
			return null;
		}


		static int ListEncodings( )
		{
			try
			{
				Console.Clear( );
			}
			catch
			{
				// Console.Clear( ) throws an IO exception if the output is redirected
			}
			int columnwidth = 8;
			EncodingInfo[] allencodings = Encoding.GetEncodings( );
			List<string> allencodingnames = new List<string>( );
			foreach ( EncodingInfo enc in allencodings )
			{
				allencodingnames.Add( enc.Name );
			}
			allencodingnames.Sort( );
			foreach ( string enc in allencodingnames )
			{
				columnwidth = Math.Max( columnwidth, enc.Length );
			}
			Console.WriteLine( "{0,-" + columnwidth + "}   {1}", "Encoding", "CodePage" );
			Console.WriteLine( "{0,-" + columnwidth + "}   {1}", "========", "========" );
			foreach ( string enc in allencodingnames )
			{
				Console.WriteLine( "{0,-" + columnwidth + "}   {1}", enc, GetEncoding( enc ).CodePage );
			}
			return 0;
		}


		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

			/*
			Rtf2Txt.exe,  Version 1.00
			Return the plain text content of a Rich Text Format (.RTF) file
 
			Usage:    Rtf2Txt.exe   rtffile  [ encoding ]
 
			or:       Rtf2Txt.exe   /E
 
			Where:    rtffile       is the path of the file to be read (no wildcards,
			                        only .rtf extension allowed)
			          encoding      is the output encoding, e.g. UTF-8 to preserve
			                        Unicode characters, or IBM437 to convert Unicode
			                        doublequotes to ASCII
			          /E            list all available encodings
			
			Notes:    If the specified encoding does not match any available encoding
			          name, the program will try again, ignoring dashes; if that does
			          not provide a match, the program will try matching the specified
			          encoding with the available encodings' codepages.
			          Return code ("errorlevel") 1 in case of errors, 0 on success.

			Credits:  Use hidden RichTextBox to convert RTF to plain text by Wendy Zang
			          https://social.msdn.microsoft.com/Forums/vstudio/en-US
			          /6e56af9b-d7d3-49f3-9ec4-80edde3fe54b/reading-modifying-rtf-files
			          ?forum=csharpgeneral#a64345e9-cfcb-43be-ab18-c08fae02cb2a
			
			Written by Rob van der Woude
			https://www.robvanderwoude.com
			*/

			#endregion Help Text


			#region Display Help Text

			Console.Error.WriteLine( );

			Console.Error.WriteLine( "Rtf2Txt.exe,  Version {0}", progver );

			Console.Error.WriteLine( "Return the plain text content of a Rich Text Format (.RTF) file" );

			Console.Error.WriteLine( );

			Console.Error.Write( "Usage:    " );
			Console.ForegroundColor = ConsoleColor.White;
			Console.Error.WriteLine( "Rtf2Txt.exe   rtffile  [ encoding ]" );
			Console.ResetColor( );

			Console.Error.WriteLine( );

			Console.Error.Write( "or:       " );
			Console.ForegroundColor = ConsoleColor.White;
			Console.Error.WriteLine( "Rtf2Txt.exe   /E" );
			Console.ResetColor( );

			Console.Error.WriteLine( );

			Console.Error.Write( "Where:    " );
			Console.ForegroundColor = ConsoleColor.White;
			Console.Error.Write( "rtffile" );
			Console.ResetColor( );
			Console.Error.WriteLine( "       is the path of the file to be read" );

			Console.Error.WriteLine( "                        (no wildcards, only .rtf extension allowed)" );

			Console.ForegroundColor = ConsoleColor.White;
			Console.Error.Write( "          encoding" );
			Console.ResetColor( );
			Console.Error.Write( "      is the output encoding, e.g. " );
			Console.ForegroundColor = ConsoleColor.White;
			Console.Error.Write( "UTF-8" );
			Console.ResetColor( );
			Console.Error.WriteLine( " to preserve" );

			Console.Error.Write( "                        Unicode characters, or " );
			Console.ForegroundColor = ConsoleColor.White;
			Console.Error.Write( "IBM437" );
			Console.ResetColor( );
			Console.Error.WriteLine( " to convert Unicode" );

			Console.Error.WriteLine( "                        doublequotes to ASCII" );

			Console.ForegroundColor = ConsoleColor.White;
			Console.Error.Write( "          /E" );
			Console.ResetColor( );
			Console.Error.WriteLine( "            list all available encodings" );

			Console.Error.WriteLine( );

			Console.Error.WriteLine( "Notes:    If the specified encoding does not match any available encoding" );

			Console.Error.WriteLine( "          name, the program will try again, ignoring dashes; if that does" );

			Console.Error.WriteLine( "          not provide a match, the program will try matching the specified" );

			Console.Error.WriteLine( "          encoding with the available encodings' codepages." );

			Console.Error.WriteLine( "          Return code (\"errorlevel\") 1 in case of errors, 0 on success." );

			Console.Error.WriteLine( );

			Console.Error.WriteLine( "Credits:  Use hidden RichTextBox to convert RTF to plain text by Wendy Zang" );

			Console.ForegroundColor = ConsoleColor.DarkGray;
			Console.Error.WriteLine( "          https://social.msdn.microsoft.com/Forums/vstudio/en-US" );

			Console.Error.WriteLine( "          /6e56af9b-d7d3-49f3-9ec4-80edde3fe54b/reading-modifying-rtf-files" );

			Console.Error.WriteLine( "          ?forum=csharpgeneral#a64345e9-cfcb-43be-ab18-c08fae02cb2a" );
			Console.ResetColor( );

			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;
		}
	}
}