class IsinValidator

class IsinValidator extends ConstraintValidator {
    public function validate(mixed $value, Constraint $constraint) : void {
        if (!$constraint instanceof Isin) {
            throw new UnexpectedTypeException($constraint, Isin::class);
        }
        if (null === $value || '' === $value) {
            return;
        }
        if (!\is_scalar($value) && !$value instanceof \Stringable) {
            throw new UnexpectedValueException($value, 'string');
        }
        $value = strtoupper($value);
        if (Isin::VALIDATION_LENGTH !== \strlen($value)) {
            $this->context
                ->buildViolation($constraint->message)
                ->setParameter('{{ value }}', $this->formatValue($value))
                ->setCode(Isin::INVALID_LENGTH_ERROR)
                ->addViolation();
            return;
        }
        if (!preg_match(Isin::VALIDATION_PATTERN, $value)) {
            $this->context
                ->buildViolation($constraint->message)
                ->setParameter('{{ value }}', $this->formatValue($value))
                ->setCode(Isin::INVALID_PATTERN_ERROR)
                ->addViolation();
            return;
        }
        if (!$this->isCorrectChecksum($value)) {
            $this->context
                ->buildViolation($constraint->message)
                ->setParameter('{{ value }}', $this->formatValue($value))
                ->setCode(Isin::INVALID_CHECKSUM_ERROR)
                ->addViolation();
        }
    }
    private function isCorrectChecksum(string $input) : bool {
        $characters = str_split($input);
        foreach ($characters as $i => $char) {
            $characters[$i] = \intval($char, 36);
        }
        $number = implode('', $characters);
        return 0 === $this->context
            ->getValidator()
            ->validate($number, new Luhn())
            ->count();
    }

}