{
  Parses the response code from the given string.
  Returns 0 if the response code could not be parsed.
}
function ParseResponseCode(const responseString: string): integer;
const
  SPACE_CHAR = ' ';
  CRLF_CHAR = #13;
  NEWLINE_CHAR = #10;
var
  crlfPos, responseStringLen: integer;
  parsedResponseCode: integer;
  responseCodeSubstring: string;
  trimmedResponseString: string;
begin
  Result := 0;
  if (responseString = '') then
    Exit;

  trimmedResponseString := RTrimCRLF(responseString);
  responseStringLen := Length(trimmedResponseString);

  crlfPos := RPos(CRLF_CHAR, trimmedResponseString);
  if (crlfPos <= responseStringLen - 3) then
  begin
    Inc(crlfPos);
    if (trimmedResponseString[crlfPos] in [CRLF_CHAR, NEWLINE_CHAR]) then
      Inc(crlfPos);

    responseCodeSubstring := Copy(trimmedResponseString, crlfPos, 3);
    if (TryStrToInt(responseCodeSubstring, parsedResponseCode)) then
    begin
      Result := parsedResponseCode;
      if ((responseStringLen > 3) and (trimmedResponseString[crlfPos + 3] <> SPACE_CHAR)) then
        Inc(Result, 1000);
    end;
  end;
end;