using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using Microsoft.Win32;


namespace RobvanderWoude
{
	internal class ListVerbs
	{
		static readonly string progver = "1.01";

		static int rc = 0;


		static int Main( string[] args )
		{
			rc = 0;
			bool verbose = false;

			if ( args.Length == 0 || args.Length > 2 || args.Contains( "/?" ) )
			{
				return ShowHelp( );
			}
			string ext = args[0];
			if ( args.Length == 2 )
			{
				if ( args[1].ToUpper( ).StartsWith( "/V" ) )
				{
					verbose = true;
				}
				else
				{
					return ShowHelp( "Invalid command line argument \"{0}\"", args[1] );
				}
			}
			if ( ext[0] != '.' )
			{
				verbose = true;
			}

			if ( verbose )
			{
				GetVerbsVerbose( args[0] );
			}
			else
			{
				GetVerbs( args[0] );
			}

			return rc;
		}


		static void GetVerbs( string ext )
		{
			ProcessStartInfo startinfo = new ProcessStartInfo( string.Format( "fakefilename{0}", ext ) );
			foreach ( string verb in startinfo.Verbs )
			{
				if ( rc == 0 )
				{
					Console.WriteLine( "Verbs for {0}", ext );
					Console.WriteLine( "=========={0}", new String( '=', ext.Length ) );
				}
				rc++;
				Console.WriteLine( verb );
			}
		}


		static void GetVerbsVerbose( string ext )
		{
			string doctype = string.Empty;
			string docname = string.Empty;
			string regkeypath = string.Format( "Software\\Classes\\{0}", ext );
			if ( ext[0] == '.' )
			{
				// get document type for specified file extension
				Console.WriteLine( "Extension = {0}", ext );
				using ( RegistryKey regkey = Registry.LocalMachine.OpenSubKey( regkeypath ) )
				{
					if ( regkey != null )
					{
						object doctypevalue = regkey.GetValue( "" );
						if ( doctypevalue != null )
						{
							doctype = doctypevalue.ToString( );
						}
					}
				}
			}
			else
			{
				// assume document type is specified on the command line
				doctype = ext;
			}
			if ( !string.IsNullOrWhiteSpace( doctype ) )
			{
				regkeypath = string.Format( "Software\\Classes\\{0}\\CurVer", doctype );
				using ( RegistryKey regkey = Registry.LocalMachine.OpenSubKey( regkeypath ) )
				{
					if ( regkey != null )
					{
						object doctypevalue = regkey.GetValue( "" );
						if ( doctypevalue != null )
						{
							doctype = doctypevalue.ToString( );
						}
					}
				}
			}
			if ( !string.IsNullOrWhiteSpace( doctype ) )
			{
				// get proper casing of docyument type, as used in the registry
				string[] classes = Registry.LocalMachine.OpenSubKey( "Software\\Classes" ).GetSubKeyNames( );
				foreach ( string classname in classes )
				{
					if ( classname.ToLower( ) == doctype.ToLower( ) )
					{
						doctype = classname;
					}
				}
				Registry.LocalMachine.Close( );
				// get friendly name for document type
				regkeypath = string.Format( "Software\\Classes\\{0}", doctype );
				using ( RegistryKey regkey = Registry.LocalMachine.OpenSubKey( regkeypath ) )
				{
					if ( regkey != null )
					{
						docname = regkey.GetValue( "" ).ToString( );
					}
				}
			}
			if ( !string.IsNullOrWhiteSpace( doctype ) )
			{
				Console.Write( "File Type = {0}", doctype );
				if ( docname != null )
				{
					Console.Write( " ({0})", docname );
				}
				Console.WriteLine( );
				// get all available verbs for this file type
				regkeypath = string.Format( "Software\\Classes\\{0}\\shell", doctype );
				using ( RegistryKey regkey = Registry.LocalMachine.OpenSubKey( regkeypath ) )
				{
					if ( regkey != null )
					{
						int columnwidth = 0;
						Console.WriteLine( "Verbs:" );
						// all verbs have a separate subkey
						foreach ( string verb in regkey.GetSubKeyNames( ) )
						{
							columnwidth = Math.Max( columnwidth, verb.Length );
						}
						foreach ( string verb in regkey.GetSubKeyNames( ) )
						{
							columnwidth = Math.Max( columnwidth, verb.Length );
							rc++;
							// get the command for this verb
							using ( RegistryKey regkeycommand = regkey.OpenSubKey( string.Format( "{0}\\command", verb ) ) )
							{
								if ( regkeycommand != null )
								{
									string command = regkeycommand.GetValue( "" ).ToString( );
									Console.WriteLine( "\t{0,-" + columnwidth + "}        {1}", verb.ToLower( ), command );
								}
							}
						}
					}
				}
			}
		}


		static int ShowHelp( params string[] errmsg )
		{
			#region Help Text

			/*
			ListVerbs.exe,  Version 1.00
			List all verbs for the specified file extension
 
			Usage:   ListVerbs   filetype  [ /V ]
 
			Where:   filetype    is the file type to list the available verbs for
			         /V          Verbose output, i.e. not just the verbs, but the
			                     associated commands as well

			Notes:   filetype can be specified as file extension including dot,
			         e.g. ".odt", or as document type name associated with a file
			         extension, e.g. "LibreOffice.WriterDocument"; in the latter
			         case, output will be verbose whether /V switch is used or not.
			         Verbose mode may sometimes find more verbs than normal mode.
			         Return code ("errorlevel") equals the number of verbs found,
			         or -1 in case of (command line) errors.

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

			#endregion Help Text


			#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 Display Help Text

			Console.Error.WriteLine( );

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

			Console.Error.WriteLine( "List all verbs for the specified file extension" );

			Console.Error.WriteLine( );

			Console.Error.Write( "Usage:   " );
			Console.ForegroundColor = ConsoleColor.White;
			Console.Error.WriteLine( "ListVerbs   filetype  [ /V ]" );
			Console.ResetColor( );

			Console.Error.WriteLine( );

			Console.Error.Write( "Where:   " );
			Console.ForegroundColor = ConsoleColor.White;
			Console.Error.Write( "filetype" );
			Console.ResetColor( );
			Console.Error.WriteLine( "    is the file type to list the available verbs for" );

			Console.ForegroundColor = ConsoleColor.White;
			Console.Error.Write( "         /V          V" );
			Console.ResetColor( );
			Console.Error.WriteLine( "erbose output, i.e. not just the verbs, but the" );

			Console.Error.WriteLine( "                     associated commands as well" );

			Console.Error.WriteLine( );

			Console.Error.Write( "Notes:   " );
			Console.ForegroundColor = ConsoleColor.White;
			Console.Error.Write( "filetype" );
			Console.ResetColor( );
			Console.Error.WriteLine( " can be specified as file extension including dot," );

			Console.Error.WriteLine( "         e.g. \".odt\", or as document type name associated with a file" );

			Console.Error.WriteLine( "         extension, e.g. \"LibreOffice.WriterDocument\"; in the latter" );

			Console.Error.Write( "         case, output will be verbose whether " );
			Console.ForegroundColor = ConsoleColor.White;
			Console.Error.Write( "/V" );
			Console.ResetColor( );
			Console.Error.WriteLine( " switch is used or not." );

			Console.Error.WriteLine( "         Verbose mode may sometimes find more verbs than normal mode." );

			Console.Error.WriteLine( "         Return code (\"errorlevel\") equals the number of verbs found," );

			Console.Error.WriteLine( "         or -1 in case of (command line) 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;
		}
	}
}