internal static string ToUniqueLocalAccount()

in LinuxCommunicator/Credentials.cs [648:711]
45 lines of code
6 McCabe index (conditional complexity)

        internal static string ToUniqueLocalAccount(string domainAccount)
        {
            if (string.IsNullOrWhiteSpace(domainAccount))
            {
                throw new ArgumentNullException("domainAccount");
            }

            string uniqueLocalAccount;

            if (domainAccount.StartsWith("NT AUTHORITY\\"))
            {
                uniqueLocalAccount = domainAccount;
            }
            else
            {
                // unique local account = Purged local name + suffix (hash code of domain account)
                string localname = Credentials.ToLocalAccount(domainAccount);

                // Remove all delimiters from the source
                string purged = RemoveChars(localname, delimiters);

                // We only take the first MaxPrefixLength characters from
                // the seed user name so as to guarantee at least 
                // MaxPrefixLength characters from the hash.
                if (purged.Length > MaxPrefixLength)
                {
                    purged = purged.Substring(0, MaxPrefixLength);
                }

                // The length is 10 or larger
                int suffixLength = MaxAccountNameLength - purged.Length;

                var builder = new StringBuilder();
                builder.Append(purged);

                using (SHA256 sha256 = SHA256.Create())
                {
                    string suffix = localname;

                    int retry = 0;
                    do
                    {
                        sha256.ComputeHash(Encoding.Default.GetBytes(suffix));
                        byte[] hash = sha256.Hash;
                        suffix = RemoveChars(Convert.ToBase64String(hash), invalidBase64UserNameChars);

                        retry++;
                        if (retry > MaxHashRetryCount)
                        {
                            throw new ApplicationException(
                                "Failed to create a hash suffix to create a user name after maximum retries.");
                        }
                    }
                    while (suffix.Length < suffixLength);

                    builder.Append(suffix.Substring(0, suffixLength));
                }

                uniqueLocalAccount = builder.ToString();

            }

            return uniqueLocalAccount;
        }