//------------------------------------------------------------------------------
// 
// System.IO.Path.cs 
//
// Copyright (C) 2001 Moonlight Enterprises, All Rights Reserved
// 
// Author:         Jim Richardson, develop@wtfo-guru.com
//                 Dan Lewis (dihlewis@yahoo.co.uk)
// Created:        Saturday, August 11, 2001 
//
//------------------------------------------------------------------------------

using System;

namespace System.IO
{
	public sealed class Path
	{
		public static readonly char AltDirectorySeparatorChar;
		public static readonly char DirectorySeparatorChar;
		public static readonly char[] InvalidPathChars;
		public static readonly char PathSeparator;
		internal static readonly string DirectorySeparatorStr;
		public static readonly char VolumeSeparatorChar;

		private static readonly char[] PathSeparatorChars;

		private Path () {}

		// class methods
		public static string ChangeExtension (string path, string extension)
		{
			if (path == null)
			{
				return null;
			}

			int iExt = findExtension (path);

			if (extension != null) {
				if (extension [0] != '.')
					extension = "." + extension;
			} else
				extension = "";
			
			if (iExt < 0) {
				return path + extension;
			} else if (iExt > 0) {
				string temp = path.Substring (0, iExt);
				return temp + extension;
			}

			return extension;
		}

		[MonoTODO]
		public static string Combine (string path1, string path2)
		{
			if (path1 == null || path2 == null)
			{
				return null;
			}

			CheckArgument.Empty (path2);

			// TODO: Check for invalid DirectoryInfo characters
			//       although I don't think it is necesary for linux

			// TODO: Verify functionality further after NUnit tests written
			//		 since the documentation was rather sketchy

			if (IsPathRooted (path2))
			{
				if (path1.Equals (string.Empty))
				{
					return path2;
				}
				throw new ArgumentException ("Rooted path");
			}
			
			string dirSep = new string (DirectorySeparatorChar, 1);
			string altSep = new string (AltDirectorySeparatorChar, 1);
			
			bool b1 = path1.EndsWith (dirSep) || path1.EndsWith (dirSep);
			bool b2 = path2.StartsWith (dirSep) || path2.StartsWith (altSep);
			if (b1 && b2)
			{
				throw new ArgumentException ("Invalid combination");
			}
			
			if (!b1 && !b2)
			{
				return path1 + dirSep + path2;
			}

			return path1 + path2;
		}

		public static string GetDirectoryName (string path)
		{
			if (path != null)
			{
				CheckArgument.Empty (path);
				CheckArgument.WhitespaceOnly (path);
				CheckArgument.PathChars (path);

				if (path.Length > 2)
				{
					int nLast = path.LastIndexOfAny (PathSeparatorChars);

					if (nLast > 0)
						return path.Substring (0, nLast);
					else
						return String.Empty;
				}
			}
			return path;
		}

		public static string GetExtension (string path)
		{
			if (path == null)
			{
				return string.Empty;
			}

			CheckArgument.Empty (path);
			CheckArgument.WhitespaceOnly (path);
			
			int iExt = findExtension (path);
			int iLastSep = path.LastIndexOfAny ( PathSeparatorChars );

			if (iExt > -1)
			{	// okay it has an extension
				return path.Substring (iExt);
			}
			return string.Empty;
		}

		public static string GetFileName (string path)
		{
			if (path == null)
			{
				return string.Empty;
			}

			CheckArgument.Empty (path);
			CheckArgument.WhitespaceOnly (path);

			int nLast = path.LastIndexOfAny (PathSeparatorChars);

			if (nLast > 0)
			{
				return path.Substring (nLast + 1);
			}

			return nLast == 0 ? null : path;
		}

		public static string GetFileNameWithoutExtension (string path)
		{
			return ChangeExtension (GetFileName (path), null);
		}

		public static string GetFullPath (string path)
		{
			if (path == null)
				throw (new ArgumentNullException (
					"path",
					"You must specify a path when calling System.IO.Path.GetFullPath"));

			if (path.StartsWith (new string (DirectorySeparatorChar, 1)) ||
						path.StartsWith (new string (AltDirectorySeparatorChar, 1)))
				return path;

			return Directory.GetCurrentDirectory () + new string (DirectorySeparatorChar, 1) + path;
		}

		public static string GetPathRoot (string path)
		{
			if (path != null || 
				(path.StartsWith (new string (DirectorySeparatorChar, 1)) ||
					path.StartsWith (new string (AltDirectorySeparatorChar, 1))))
			{
				return path.Substring (0, 1);
			}
			return null;
		}

		public static string GetTempFileName ()
		{
			string path;
			Random rnd;
			int num;
			rnd = new Random ();
			num = rnd.Next ();
			path = GetTempPath() + DirectorySeparatorChar + "tmp" + num.ToString("x");
			while (File.Exists(path) || Directory.Exists(path)) {    
				num = rnd.Next ();
				path = GetTempPath() + DirectorySeparatorChar + "tmp" + num.ToString("x");
			}
			FileStream f = File.Create(path);
			f.Close();
			return path;
		}

		/// <summary>
		/// Returns the path of the current systems temp directory
		/// </summary>
		[MonoTODO]
		public static string GetTempPath ()
		{	// TODO: This might vary with distribution and there
			//       might be an api to provide it. Research is needed
			return "/tmp";
		}

		public static bool HasExtension (string path)
		{  
			CheckArgument.Null (path);
			CheckArgument.Empty (path);
			CheckArgument.WhitespaceOnly (path);
			
			return findExtension (path) > -1;
		}

		public static bool IsPathRooted (string path)
		{
			return path.StartsWith (new string (VolumeSeparatorChar,1));
		}

		// private class methods

		private static int findExtension (string path)
		{
			// method should return the index of the path extension
			// start or -1 if no valid extension
			if (path != null){
				int iLastDot = path.LastIndexOf (".");
				int iLastSep = path.LastIndexOfAny ( PathSeparatorChars );

				if (iLastDot > iLastSep)
					return iLastDot;
			}
			return -1;
		}

		static Path () {
			VolumeSeparatorChar = MonoIO.VolumeSeparatorChar;
			DirectorySeparatorChar = MonoIO.DirectorySeparatorChar;
			AltDirectorySeparatorChar = MonoIO.AltDirectorySeparatorChar;

			PathSeparator = MonoIO.PathSeparator;
			InvalidPathChars = MonoIO.InvalidPathChars;

			// internal fields

			DirectorySeparatorStr = DirectorySeparatorChar.ToString ();
			PathSeparatorChars = new char [] {
				DirectorySeparatorChar,
				AltDirectorySeparatorChar,
				VolumeSeparatorChar
			};
		}
	}
}