A WPF Template solution using MVVM and Castle Windsor

using System;
using System.IO;

namespace CommonUtilities
{
	public class FileHelper
	{
		/// <summary>
		/// rename file to tmp name - the method also makes sure that the result file length is not exceeding the 
		/// allowed file name length in NTFS
		/// In case the file name exceed it is trimmed!
		/// </summary>
		/// <param name="fileName">file name</param>
		/// <returns>tmp file name</returns>
		public static string Rename2Tmp(ref string fileName)
		{
		    string originalName = fileName;
			string tmpFileName = TmpFileName(ref fileName);
            File.Move(originalName, tmpFileName);
			return tmpFileName;
		}
		
	    private const int TEMP_FILE_BUFFER = 45;
	    private const int MAX_FILE_LENGH = 260;

        /// <summary>
        /// Temporaries the name of the file.
        /// </summary>
        /// <param name="fileName">Name of the file.</param>
        /// <returns></returns>
        public static string TmpFileName(string fileName)
        {
            return TmpFileName(ref fileName);
        }
		
		/// <summary>
        /// Generate tmp file name - the method also makes sure that the result file length is not exceeding the 
        /// allowed file name length in NTFS
        /// In case the file name exceed it is trimmed!
		/// </summary>
		/// <param name="fileName"></param>
		/// <returns></returns>
		public static string TmpFileName(ref string fileName)
		{
			string dirName = Path.GetDirectoryName(fileName) ?? string.Empty;
		    string extName = Path.GetExtension(fileName);
		    string fileNoExt = Path.GetFileNameWithoutExtension(fileName);

            if (fileName.Length >= MAX_FILE_LENGH - TEMP_FILE_BUFFER) // taking 60 chars as buffer
            {
                int trimSize = Math.Min(TEMP_FILE_BUFFER, fileName.Length - (MAX_FILE_LENGH - TEMP_FILE_BUFFER));
                if (fileNoExt.Length > trimSize)
                {
                    fileNoExt = fileNoExt.Substring(0, fileNoExt.Length - trimSize);
                    fileName = Path.Combine(dirName, fileNoExt + extName);
                }
            }

			string tmpFileName = string.Format(@"{0}{1}{2}{3}{4}{5}{6}{7}", 
                dirName, (dirName.Length > 0 ? @"\" : ""), 
                fileNoExt, 
                "{", System.Guid.NewGuid(), "}", 
                ".tmp", 
                !string.IsNullOrEmpty(extName) ? Path.GetExtension(fileName).Replace(".", "~"):  "~");
			//
			return tmpFileName;
		}

        /// <summary>
		/// original file name from tmp file name
		/// </summary>
		/// <param name="fileName"></param>
		/// <returns></returns>
		public static string Tmp2OriginalName(string fileName)
		{
			string extName = Path.GetExtension(fileName);

			if (extName.Length > 4)
			{
				// validate
				if (extName.Substring(0, 5) != ".tmp~") //when not a temporary name
				{
					return fileName;
				}
				extName = extName.Substring(4).Replace("~", ".");
			}

			string dirName = Path.GetDirectoryName(fileName);
			string bodyName = Path.GetFileNameWithoutExtension(fileName);

			if (bodyName.Length > 38) //when contains Guid
			{
				bodyName = bodyName.Substring(0, bodyName.Length - 38);
			}

			string orgFileName = string.Format(@"{0}{1}{2}{3}", 
                dirName, 
                (dirName.Length > 0 ? @"\" : ""), 
                bodyName, 
                extName != "." ? 
                extName : string.Empty);
			//
			return orgFileName;
		}

	}
}