function LuhnValidator::validate

Overrides ConstraintValidatorInterface::validate

File

vendor/symfony/validator/Constraints/LuhnValidator.php, line 33

Class

LuhnValidator

Validates a PAN using the LUHN Algorithm.

Namespace

Symfony\Component\Validator\Constraints

Code

public function validate(mixed $value, Constraint $constraint) : void {
    if (!$constraint instanceof Luhn) {
        throw new UnexpectedTypeException($constraint, Luhn::class);
    }
    if (null === $value || '' === $value) {
        return;
    }
    // Work with strings only, because long numbers are represented as floats
    // internally and don't work with strlen()
    if (!\is_string($value) && !$value instanceof \Stringable) {
        throw new UnexpectedValueException($value, 'string');
    }
    $value = (string) $value;
    if (!ctype_digit($value)) {
        $this->context
            ->buildViolation($constraint->message)
            ->setParameter('{{ value }}', $this->formatValue($value))
            ->setCode(Luhn::INVALID_CHARACTERS_ERROR)
            ->addViolation();
        return;
    }
    $checkSum = 0;
    $length = \strlen($value);
    for ($i = $length - 1; $i >= 0; --$i) {
        if ($i % 2 ^ $length % 2) {
            // Starting with the last digit and walking left, add every second
            // digit to the check sum
            // e.g. 7  9  9  2  7  3  9  8  7  1  3
            //      ^     ^     ^     ^     ^     ^
            //    = 7  +  9  +  7  +  9  +  7  +  3
            $checkSum += (int) $value[$i];
        }
        else {
            // Starting with the second last digit and walking left, double every
            // second digit and add it to the check sum
            // For doubles greater than 9, sum the individual digits
            // e.g. 7  9  9  2  7  3  9  8  7  1  3
            //         ^     ^     ^     ^     ^
            //    =    1+8 + 4  +  6  +  1+6 + 2
            $checkSum += (int) (2 * $value[$i] / 10) + 2 * $value[$i] % 10;
        }
    }
    if (0 === $checkSum || 0 !== $checkSum % 10) {
        $this->context
            ->buildViolation($constraint->message)
            ->setParameter('{{ value }}', $this->formatValue($value))
            ->setCode(Luhn::CHECKSUM_FAILED_ERROR)
            ->addViolation();
    }
}