validateCreditCard static method

String? validateCreditCard(String? value)

Validate credit card number

Implementation

static String? validateCreditCard(String? value) {
  if (value == null || value.isEmpty) {
    return 'Credit card number is required.';
  }

  // Remove spaces and dashes
  String cleanNumber = value.replaceAll(RegExp(r'[\s-]'), '');

  // Check if it contains only digits
  if (!RegExp(r'^\d+$').hasMatch(cleanNumber)) {
    return 'Credit card number should contain only digits.';
  }

  // Check length (typically 13-19 digits)
  if (cleanNumber.length < 13 || cleanNumber.length > 19) {
    return 'Invalid credit card number length.';
  }

  // Luhn algorithm validation
  if (!_luhnCheck(cleanNumber)) {
    return 'Invalid credit card number.';
  }

  return null;
}