validateExpirationDate function

ValidationResults validateExpirationDate(String expDateStr)

Validates the card's expiration date

The expiration date must be in one of the following date formats:

• 'MM/YY'
• 'MM/YYY'
• 'MM/YYYY'

Implementation

ValidationResults validateExpirationDate(String expDateStr) {
  if (expDateStr.isEmpty) {
    return ValidationResults(
      isValid: false,
      isPotentiallyValid: false,
      message: 'No date given',
    );
  }

  List<String> monthAndYear = _parseDate(expDateStr);
  if (monthAndYear.isEmpty) {
    return ValidationResults(
      isValid: false,
      isPotentiallyValid: false,
      message: 'Invalid date format or invalid dates',
    );
  }

  ExpMonthValidationResults monthValidation =
      _validateExpMonth(monthAndYear[0]);
  ExpYearValidationResults yearValidation =
      _validateExpYear(monthAndYear[1]);

  if (monthValidation.isValid) {
    if (yearValidation.expiresThisYear) {
      // If the card expires this year then tell whether or not it has expired already
      return ValidationResults(
        isValid: monthValidation.isValidForCurrentYear,
        isPotentiallyValid: monthValidation.isValidForCurrentYear,
        message: yearValidation
            .message, // If year validation failed then this will be set
      );
    }

    // Valid expiration date, all is well
    if (yearValidation.isValid) {
      return ValidationResults(
        isValid: true,
        isPotentiallyValid: true,
      );
    }
  }

  // Still a potentially valid expiration date
  if (monthValidation.isPotentiallyValid &&
      yearValidation.isPotentiallyValid) {
    return ValidationResults(
      isValid: false,
      isPotentiallyValid: true,
    );
  }

  return ValidationResults(
    isValid: false,
    isPotentiallyValid: false,
    message: monthValidation.message,
  );
}