using System;
using System.Diagnostics;
using System.Runtime.InteropServices;

// Source: "How to get the parent process that launched a C# application?" by Jared Barneck
// http://www.rhyous.com/2010/04/30/how-to-get-the-parent-process-that-launched-a-c-application/

namespace ParentProcess
{
	public class ParentProcess
	{
		public static String ProcessName
		{
			get { return GetParentProcess( ).ProcessName; }
		}

		public static int ProcessId
		{
			get { return GetParentProcess( ).Id; }
		}

		public static String FullPath
		{
			get
			{
				return GetParentProcess( ).MainModule.FileName;
			}
		}

		public static String FileName
		{
			get
			{
				return System.IO.Path.GetFileName( GetParentProcess( ).MainModule.FileName );
			}
		}

		public static String DirectoryName
		{
			get
			{
				return System.IO.Path.GetDirectoryName( GetParentProcess( ).MainModule.FileName );
			}
		}

		private static Process GetParentProcess( )
		{
			int iParentPid = 0;
			int iCurrentPid = Process.GetCurrentProcess( ).Id;

			IntPtr oHnd = CreateToolhelp32Snapshot( TH32CS_SNAPPROCESS, 0 );

			if ( oHnd == IntPtr.Zero )
				return null;

			PROCESSENTRY32 oProcInfo = new PROCESSENTRY32( );

			oProcInfo.dwSize =
			(uint) System.Runtime.InteropServices.Marshal.SizeOf( typeof( PROCESSENTRY32 ) );

			if ( Process32First( oHnd, ref oProcInfo ) == false )
				return null;

			do
			{
				if ( iCurrentPid == oProcInfo.th32ProcessID )
					iParentPid = (int) oProcInfo.th32ParentProcessID;
			}
			while ( iParentPid == 0 && Process32Next( oHnd, ref oProcInfo ) );

			if ( iParentPid > 0 )
				return Process.GetProcessById( iParentPid );
			else
				return null;
		}

		static uint TH32CS_SNAPPROCESS = 2;

		[StructLayout( LayoutKind.Sequential )]
		public struct PROCESSENTRY32
		{
			public uint dwSize;
			public uint cntUsage;
			public uint th32ProcessID;
			public IntPtr th32DefaultHeapID;
			public uint th32ModuleID;
			public uint cntThreads;
			public uint th32ParentProcessID;
			public int pcPriClassBase;
			public uint dwFlags;
			[MarshalAs( UnmanagedType.ByValTStr, SizeConst = 260 )]
			public string szExeFile;
		};

		[DllImport( "kernel32.dll", SetLastError = true )]
		static extern IntPtr CreateToolhelp32Snapshot( uint dwFlags, uint th32ProcessID );

		[DllImport( "kernel32.dll" )]
		static extern bool Process32First( IntPtr hSnapshot, ref PROCESSENTRY32 lppe );

		[DllImport( "kernel32.dll" )]
		static extern bool Process32Next( IntPtr hSnapshot, ref PROCESSENTRY32 lppe );
	}
}