using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Management;
using System.Windows.Forms;


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


		static int Main( string[] args )
		{
			#region Parse Command Line

			// Only 3 valid arguments are checked, invalid arguments are ignored
			if ( args.Contains( "/?", StringComparer.InvariantCultureIgnoreCase ) )
			{
				return ShowHelp( );
			}
			bool quiet = args.Contains( "/quiet", StringComparer.InvariantCultureIgnoreCase ) || args.Contains( "/q", StringComparer.InvariantCultureIgnoreCase );
			bool verbose = args.Contains( "/verbose", StringComparer.InvariantCultureIgnoreCase ) || args.Contains( "/v", StringComparer.InvariantCultureIgnoreCase );

			#endregion Parse Command Line


			#region Initialize Variables

			ConsoleColor fgcolor;
			string[] PATH;
			int errors = 0;
			int notexist = 0;
			int empty = 0;

			#endregion Initialize Variables


			#region System PATH

			Console.WriteLine( );
			Console.WriteLine( "System PATH" );
			Console.WriteLine( "===========" );
			string query = @"SELECT * FROM Win32_Environment WHERE Name='PATH' AND SystemVariable=TRUE";
			ManagementObjectSearcher searcher = new ManagementObjectSearcher( "root\\CIMV2", query );
			ManagementObjectCollection colItems = searcher.Get( );
			foreach ( ManagementObject item in colItems )
			{
				if ( verbose )
				{
					Console.ForegroundColor = ConsoleColor.White;
					Console.WriteLine( "PATH={0}", item["VariableValue"] );
					Console.ResetColor( );
					Console.WriteLine( );
				}
				PATH = item["VariableValue"].ToString( ).Split( ';' );
				foreach ( string folder in PATH )
				{
					if ( string.IsNullOrWhiteSpace( folder ) )
					{
						Console.ForegroundColor = ConsoleColor.Red;
						Console.WriteLine( "<empty>" );
						Console.ResetColor( );
						errors++;
						empty++;
					}
					else
					{
						if ( Directory.Exists( Environment.ExpandEnvironmentVariables( folder ) ) )
						{
							fgcolor = ConsoleColor.Green;
						}
						else
						{
							fgcolor = ConsoleColor.Red;
							errors++;
							notexist++;
						}
						Console.ForegroundColor = fgcolor;
						Console.WriteLine( folder );
					}
				}
				Console.ResetColor( );
			}
			Console.WriteLine( );

			#endregion System PATH


			#region User PATH

			Console.WriteLine( );
			Console.WriteLine( "User PATH" );
			Console.WriteLine( "=========" );
			query = string.Format( @"SELECT * FROM Win32_Environment WHERE Name='PATH' AND UserName='{0}\\{1}'", Environment.GetEnvironmentVariable( "ComputerName" ), Environment.UserName );
			searcher = new ManagementObjectSearcher( "root\\CIMV2", query );
			colItems = searcher.Get( );
			foreach ( ManagementObject item in colItems )
			{
				if ( verbose )
				{
					Console.ForegroundColor = ConsoleColor.White;
					Console.WriteLine( "PATH={0}", item["VariableValue"] );
					Console.ResetColor( );
					Console.WriteLine( );
				}
				PATH = item["VariableValue"].ToString( ).Split( ';' );
				foreach ( string folder in PATH )
				{
					if ( string.IsNullOrWhiteSpace( folder ) )
					{
						Console.ForegroundColor = ConsoleColor.Red;
						Console.WriteLine( "<empty>" );
						Console.ResetColor( );
						errors++;
						empty++;
					}
					else
					{
						if ( Directory.Exists( Environment.ExpandEnvironmentVariables( folder ) ) )
						{
							fgcolor = ConsoleColor.Green;
						}
						else
						{
							fgcolor = ConsoleColor.Red;
							errors++;
							notexist++;
						}
						Console.ForegroundColor = fgcolor;
						Console.WriteLine( folder );
					}
				}
				Console.ResetColor( );
			}
			Console.WriteLine( );

			#endregion User PATH


			#region Error Warning

			if ( verbose)
			{
				if ( empty > 0)
				{
					fgcolor = ConsoleColor.Red;
				}
				else
				{
					fgcolor= ConsoleColor.Green;
				}
				Console.ForegroundColor = fgcolor;
				Console.Write( "\n{0} empty", empty );
				Console.ResetColor( );
				Console.Write( " and " );
				if ( notexist > 0 )
				{
					fgcolor = ConsoleColor.Red;
				}
				else
				{
					fgcolor = ConsoleColor.Green;
				}
				Console.ForegroundColor = fgcolor;
				Console.Write( "{0} non existing", notexist );
				Console.ResetColor( );
				Console.WriteLine( " PATH entries were found.\n" );
			}

			if ( !quiet && errors > 0 )
			{
				string message = string.Empty;
				if ( empty > 0 && notexist == 0 )
				{
					message = string.Format( "{0} empty PATH entr{1} found.", empty, ( empty == 1 ? "y was" : "ies were" ) );
				}
				else if ( empty == 0 && notexist > 0 )
				{
					message = string.Format( "{0} non existing PATH entr{1} found.", notexist, ( notexist == 1 ? "y was" : "ies were" ) );
				}
				else
				{
					message = string.Format( "{0} empty and {1} non existing PATH entries were found.", empty, notexist );
				}
				message += "\n\nIn the \"System Properties\" window, \"Advanced\" tab, click the \"Environment ";
				message += string.Format( "Variables\" button and correct the error{0}", ( errors == 1 ? "" : "s" ) );
				string title = string.Format( "Correct {0} error{1}", errors, ( errors == 1 ? "" : "s" ) );
				DialogResult answer = MessageBox.Show( message, title, MessageBoxButtons.OKCancel, MessageBoxIcon.Error );
				if ( answer == DialogResult.OK )
				{
					try
					{
						Process.Start( "SystemPropertiesAdvanced.exe" ).WaitForExit( );
					}
					catch ( Exception )
					{
						// With RunDLL32 we don't WaitForExit, as it exits immediately after launching the Control Panel applet
						Process.Start( "RunDLL32.exe", "Shell32.dll,Control_RunDLL SYSDM.CPL,@0,3" );
					}
				}
			}

			#endregion Error Warning


			return errors;
		}


		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

			/*
			CheckPath.exe,  Version 1.00
			Check if all directories in the PATH variable(s) really exist
 
			Usage:    CheckPath.exe  [ /Quiet ]  [ /Verbose ]  [ /? ]
 
			Where:    /Quiet     skips the popup message when errors are found
			          /Verbose   shows extra information, i.e. full PATH variables
			          /?         shows this help screen
 
			Notes:    Each directory in the System PATH and the User PATH will be checked.
			          If it exists, its name is displayed in green, otherwise in red.
			          A counter keeps track of errors, i.e. empty PATH entries as well as
			          directories that don't exist, and its count is used as the program's
			          return code.
			          Unless the /Quiet switch is used, a popup message will show the number
			          of errors detected, if any, and explain how to correct this.
			          If "OK" is clicked, the "System Properties" settings window's
			          "Advanced" tab is opened: click its "Environment Variables" button and
			          correct the errors. If "Cancel" is clicked, no settings window is
			          opened, and the program terminates.
 
			Written by Rob van der Woude
			https://www.robvanderwoude.com
			*/

			Console.Error.WriteLine( );

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

			Console.Error.WriteLine( "Check if all directories in the PATH variable(s) really exist" );

			Console.Error.WriteLine( );

			Console.Error.Write( "Usage:    " );
			Console.ForegroundColor = ConsoleColor.White;
			Console.Error.WriteLine( "CheckPath.exe  [ /Quiet ]  [ /Verbose ]  [ /? ]" );
			Console.ResetColor( );

			Console.Error.WriteLine( );

			Console.Error.Write( "Where:    " );
			Console.ForegroundColor = ConsoleColor.White;
			Console.Error.Write( "/Q" );
			Console.ResetColor( );
			Console.Error.WriteLine( "uiet     skips the popup message when errors are found" );

			Console.ForegroundColor = ConsoleColor.White;
			Console.Error.Write( "          /V" );
			Console.ResetColor( );
			Console.Error.WriteLine( "erbose   shows extra information, i.e. full PATH variables" );

			Console.ForegroundColor = ConsoleColor.White;
			Console.Error.Write( "          /?" );
			Console.ResetColor( );
			Console.Error.WriteLine( "         shows this help screen" );

			Console.Error.WriteLine( );

			Console.Error.WriteLine( "Notes:    Each directory in the System PATH and the User PATH will be checked." );

			Console.Error.Write( "          If it exists, its name is displayed in " );
			Console.ForegroundColor = ConsoleColor.Green;
			Console.Error.Write( "green" );
			Console.ResetColor( );
			Console.Error.Write( ", otherwise in " );
			Console.ForegroundColor = ConsoleColor.Red;
			Console.Error.Write( "red" );
			Console.ResetColor( );
			Console.Error.WriteLine( "." );

			Console.Error.WriteLine( "          A counter keeps track of errors, i.e. empty PATH entries as well as" );

			Console.Error.WriteLine( "          directories that don't exist, and its count is used as the program's" );

			Console.Error.WriteLine( "          return code." );

			Console.Error.Write( "          Unless the " );
			Console.ForegroundColor = ConsoleColor.White;
			Console.Error.Write( "/Q" );
			Console.ResetColor( );
			Console.Error.WriteLine( "uiet switch is used, a popup message will show the number" );

			Console.Error.WriteLine( "          of errors detected, if any, and explain how to correct this." );
			          
			Console.Error.WriteLine( "          If \"OK\" is clicked, the \"System Properties\" settings window's" );

			Console.Error.WriteLine( "          \"Advanced\" tab is opened: click its \"Environment Variables\" button and" );

			Console.Error.WriteLine( "          correct the errors. If \"Cancel\" is clicked, no settings window is" );

			Console.Error.WriteLine( "          opened, and the program terminates." );

			Console.Error.WriteLine( );

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

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

			#endregion Help Text

			return -1;
		}
	}
}