using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;


namespace RobvanderWoude
{
	internal class Doc2Txt
	{
		static string progver = "1.00";


		static int Main( string[] args )
		{
			if ( args.Length != 1 || args[0] == "/?" )
			{
				return ShowHelp( );
			}
			string docfile = args[0];
			if ( !File.Exists( docfile ) )
			{
				return ShowHelp( "File not found: \"{0}\"", docfile );
			}
			if ( Path.GetExtension( docfile ).ToLower( ) != ".doc" )
			{
				return ShowHelp( "This program can extract text from .DOC files only" );
			}

			string doccontent = string.Empty;
			try
			{
				StreamReader sr = new StreamReader( docfile, false );
				doccontent = sr.ReadToEnd( ).Trim( "\n\t ".ToCharArray( ) );
				sr.Close( );
			}
			catch ( IOException )
			{
				return ShowHelp( "Access to file \"{0}\" denied", docfile );
			}
			if ( doccontent.Length == 0 )
			{
				return ShowHelp( "An error occurred while trying to extract text from \"{0}\"", docfile );
			}
			if ( doccontent.Contains( "[Content_Types]" ) )
			{
				doccontent = doccontent.Substring( 0, doccontent.IndexOf( "[Content_Types]" ) );
			}
			string plaintext = string.Empty;
			Regex regex = new Regex( "[^\\000\\015\\367\\377]{20,}" );
			MatchCollection matches = regex.Matches( doccontent );
			if ( matches.Count == 0 )
			{
				return ShowHelp( "An error occurred while trying to extract text from \"{0}\"", docfile );
			}
			foreach ( Match match in matches )
			{
				string matchingtext = match.Value.Trim( "\n\t ".ToCharArray( ) );
				if ( Encoding.UTF8.GetByteCount( matchingtext ) == matchingtext.Length && !matchingtext.Contains( (char)4 ) )
				{
					plaintext += matchingtext + "\n";
				}
			}

			Console.WriteLine( plaintext );

			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

			/*
			Doc2Txt.exe,  Version 1.00
			Return the plain text content of a Word .DOC file without requiring Word
 
			Usage:    Doc2Txt.exe  docxfile
 
			Where:    docfile      is the path of the Word file to be read
			                       (no wildcards, only .doc extension allowed)
 
			Note:     Return code ("errorlevel") 1 in case of errors, 0 on success.
 
			Written by Rob van der Woude
			https://www.robvanderwoude.com
			*/

			#endregion Help Text


			#region Display Help Text

			Console.Error.WriteLine( );

			Console.Error.WriteLine( "Doc2Txt.exe,  Version {0}", progver );

			Console.Error.WriteLine( "Return the plain text content of a Word .DOC file without requiring Word" );

			Console.Error.WriteLine( );

			Console.Error.Write( "Usage:    " );
			Console.ForegroundColor = ConsoleColor.White;
			Console.Error.WriteLine( "Doc2Txt.exe  docfile" );
			Console.ResetColor( );

			Console.Error.WriteLine( );

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

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

			Console.Error.WriteLine( );

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

			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;
		}
	}
}