using System;
using System.Globalization;
using System.IO;

namespace System.Web.Util
{
	internal sealed class FileUtils
	{
		internal delegate bool CreateTempFile (string path);

		static Random rnd;

		internal static Random Rnd 
		{
                        get {
				lock (rnd) {
					if (rnd == null)
						rnd = new Random ();
				}
				
				return rnd;
			}
		}
		
		internal static void GetTempFileName (string tempdir, CreateTempFile createFile)
		{
			 GetTempFileName (tempdir, null, createFile);
		}

		internal static void GetTempFileName (string tempdir, string extension, CreateTempFile createFile)
		{
			if (tempdir == null || tempdir.Length == 0)
				return;
			if (createFile == null)
				return;
			Random rnd = Rnd;
			string path = null;
			bool done = false;
			
			do {
                                int num = rnd.Next ();
                                num++;
                                path = Path.Combine (tempdir, num.ToString ("x", CultureInfo.InvariantCulture));
                                if (extension != null)
                                        path = String.Format ("{0}.{1}", path, extension);
                                        
                                try {
                                        done = createFile (path);
                                } catch (System.IO.IOException) {
                                } catch { throw; }
                        } while (!done);
		}
	}
}