--- /dev/null
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\Validator\Constraints;
+
+use Symfony\Component\Validator\Context\ExecutionContextInterface;
+use Symfony\Component\Validator\Constraint;
+use Symfony\Component\Validator\ConstraintValidator;
+use Symfony\Component\Validator\Exception\UnexpectedTypeException;
+
+/**
+ * Validates a PAN using the LUHN Algorithm.
+ *
+ * For a list of example card numbers that are used to test this
+ * class, please see the LuhnValidatorTest class.
+ *
+ * @see http://en.wikipedia.org/wiki/Luhn_algorithm
+ *
+ * @author Tim Nagel <t.nagel@infinite.net.au>
+ * @author Greg Knapp http://gregk.me/2011/php-implementation-of-bank-card-luhn-algorithm/
+ * @author Bernhard Schussek <bschussek@gmail.com>
+ */
+class LuhnValidator extends ConstraintValidator
+{
+ /**
+ * Validates a credit card number with the Luhn algorithm.
+ *
+ * @param mixed $value
+ * @param Constraint $constraint
+ *
+ * @throws UnexpectedTypeException when the given credit card number is no string
+ */
+ public function validate($value, Constraint $constraint)
+ {
+ if (!$constraint instanceof Luhn) {
+ throw new UnexpectedTypeException($constraint, __NAMESPACE__.'\Luhn');
+ }
+
+ 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) && !(is_object($value) && method_exists($value, '__toString'))) {
+ throw new UnexpectedTypeException($value, 'string');
+ }
+
+ $value = (string) $value;
+
+ if (!ctype_digit($value)) {
+ if ($this->context instanceof ExecutionContextInterface) {
+ $this->context->buildViolation($constraint->message)
+ ->setParameter('{{ value }}', $this->formatValue($value))
+ ->setCode(Luhn::INVALID_CHARACTERS_ERROR)
+ ->addViolation();
+ } else {
+ $this->buildViolation($constraint->message)
+ ->setParameter('{{ value }}', $this->formatValue($value))
+ ->setCode(Luhn::INVALID_CHARACTERS_ERROR)
+ ->addViolation();
+ }
+
+ return;
+ }
+
+ $checkSum = 0;
+ $length = strlen($value);
+
+ // 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
+ for ($i = $length - 1; $i >= 0; $i -= 2) {
+ $checkSum += $value[$i];
+ }
+
+ // 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
+ for ($i = $length - 2; $i >= 0; $i -= 2) {
+ $checkSum += array_sum(str_split($value[$i] * 2));
+ }
+
+ if (0 === $checkSum || 0 !== $checkSum % 10) {
+ if ($this->context instanceof ExecutionContextInterface) {
+ $this->context->buildViolation($constraint->message)
+ ->setParameter('{{ value }}', $this->formatValue($value))
+ ->setCode(Luhn::CHECKSUM_FAILED_ERROR)
+ ->addViolation();
+ } else {
+ $this->buildViolation($constraint->message)
+ ->setParameter('{{ value }}', $this->formatValue($value))
+ ->setCode(Luhn::CHECKSUM_FAILED_ERROR)
+ ->addViolation();
+ }
+ }
+ }
+}