// see https://howtodoinjava.com/java/regex/java-regex-validate-international-phone-numbers/

sclass InternationalPhoneValidator {

  S rawInput;

  S filtered;

  L<CountryDialCode> dialCodes; // might be multiple countries with same code

  S countryPart, localPart;

  bool valid;

  S error;

  *() {}

  *(S *rawInput) {}

  // needs rawInput

  run {

    filtered = dropPrefix("+", dropSpecialChars(rawInput));

    if (!isAllDigits(filtered)) ret with error = "Bad characters";

    splitLocal();

  }

  S dropSpecialChars(S s) {

    ret replaceAll(s, "[\\s\\(\\)\\-]", "");

  }

  void splitLocal {

    S countryPart = longestPrefixInNavigableSet(filtered, navigableKeys(countryDialCodes_rawNumbersTreeMultiMap()));

    if (countryPart == null) ret with error = "Invalid country code";

    dialCodes = countryDialCodes_rawNumbersTreeMultiMap().get(countryPart);

    localPart = dropPrefix(countryPart, filtered);

    if (l(filtered) < 7) ret with error = "Phone number too short";

    else if (l(filtered) > 15) ret with error = "Phone number too long";

    valid = true;

  }

}