validate static method

String? validate(String number, CountryModel country)

Validates number against country length constraints.

Returns null when valid, or a localised error string.

Implementation

static String? validate(String number, CountryModel country) {
  final clean = number.replaceAll(RegExp(r'\D'), '');

  if (clean.isEmpty) {
    return 'Phone number is required';
  }
  if (clean.length < country.minLength) {
    return 'Enter at least ${country.minLength} digits  '
        '(e.g. ${country.example})';
  }
  if (clean.length > country.maxLength) {
    return 'Maximum ${country.maxLength} digits allowed';
  }
  return null;
}