KeePass.Util.Archive.ImageArchive.GetID C# (CSharp) Method

        private static string GetID(string strFileName)
        {
            if(strFileName == null) { Debug.Assert(false); return string.Empty; }

            string str = strFileName;
            if(str.Length == 0) return string.Empty;

            char chFirst = str[0];
            if((chFirst == 'B') || (chFirst == 'b'))
            {
                int pL = str.IndexOf('_');
                int pR = str.LastIndexOf('.');
                if((pL >= 0) && (pR > pL))
                    str = str.Substring(pL + 1, pR - pL - 1);
                else if(pL >= 0)
                    str = str.Substring(pL + 1);
            }
            else str = UrlUtil.StripExtension(str);

            return str.ToLowerInvariant();
        }