ArgusTV.Recorders.Common.ShareExplorer.GetUncPathForLocalPath C# (CSharp) Method

        public static string GetUncPathForLocalPath(string fileName)
        {
            if (String.IsNullOrEmpty(fileName))
            {
                return String.Empty;
            }
            if (fileName.StartsWith(@"\\"))
            {
                return fileName;
            }

            fileName = Path.GetFullPath(fileName);
            if (!IsValidLocalFilePath(fileName) || !Directory.Exists(fileName))
            {
                return String.Empty;
            }

            int nRet = 0;
            UNIVERSAL_NAME_INFO rni = new UNIVERSAL_NAME_INFO();
            int bufferSize = Marshal.SizeOf(rni);

            nRet = WNetGetUniversalName(fileName, UNIVERSAL_NAME_INFO_LEVEL, ref rni, ref bufferSize);

            if (nRet == ERROR_MORE_DATA)
            {
                IntPtr pBuffer = Marshal.AllocHGlobal(bufferSize); ;
                try
                {
                    nRet = WNetGetUniversalName(fileName, UNIVERSAL_NAME_INFO_LEVEL, pBuffer, ref bufferSize);
                    if (NO_ERROR == nRet)
                    {
                        rni = (UNIVERSAL_NAME_INFO)Marshal.PtrToStructure(pBuffer, typeof(UNIVERSAL_NAME_INFO));
                    }
                }
                finally
                {
                    Marshal.FreeHGlobal(pBuffer);
                }
            }

            switch (nRet)
            {
                case NO_ERROR:
                    return rni.lpUniversalName;

                case ERROR_NOT_CONNECTED:
                    //Local file-name
                    List<ShareInfo> shareInfoList = GetShareInfo();
                    if (shareInfoList != null)
                    {
                        ShareInfo shareInfo = FindBestShareInfoMatch(shareInfoList, fileName);
                        if (shareInfo != null)
                        {
                            // TODO : (Steph) verify what this ugly code is doing ...
                            string path = shareInfo.Path;
                            if (!String.IsNullOrEmpty(path))
                            {
                                int index = path.Length;
                                if (Path.DirectorySeparatorChar != path[path.Length - 1])
                                {
                                    index++;
                                }

                                if (index < fileName.Length)
                                {
                                    fileName = fileName.Substring(index);
                                }
                                else
                                {
                                    fileName = String.Empty;
                                }
                                return Path.Combine(shareInfo.ToString(), fileName);
                            }
                        }
                    }
                    return String.Empty;

                default:
                    return String.Empty;
            }
        }