class UuidValidator

class UuidValidator extends ConstraintValidator {
    // The strict pattern matches UUIDs like this:
    // xxxxxxxx-xxxx-Mxxx-Nxxx-xxxxxxxxxxxx
    // Roughly speaking:
    // x = any hexadecimal character
    // M = any allowed version {1..8}
    // N = any allowed variant {8, 9, a, b}
    public const STRICT_LENGTH = 36;
    public const STRICT_FIRST_HYPHEN_POSITION = 8;
    public const STRICT_LAST_HYPHEN_POSITION = 23;
    public const STRICT_VERSION_POSITION = 14;
    public const STRICT_VARIANT_POSITION = 19;
    // The loose pattern validates similar yet non-compliant UUIDs.
    // Hyphens are completely optional. If present, they should only appear
    // between every fourth character:
    // xxxx-xxxx-xxxx-xxxx-xxxx-xxxx-xxxx-xxxx
    // xxxxxxxxxxxx-xxxx-xxxx-xxxx-xxxx-xxxx
    // xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
    // The value can also be wrapped with characters like []{}:
    // {xxxx-xxxx-xxxx-xxxx-xxxx-xxxx-xxxx-xxxx}
    // Neither the version nor the variant is validated by this pattern.
    public const LOOSE_MAX_LENGTH = 39;
    public const LOOSE_FIRST_HYPHEN_POSITION = 4;
    public function validate(mixed $value, Constraint $constraint) : void {
        if (!$constraint instanceof Uuid) {
            throw new UnexpectedTypeException($constraint, Uuid::class);
        }
        if (null === $value || '' === $value) {
            return;
        }
        if (!\is_scalar($value) && !$value instanceof \Stringable) {
            throw new UnexpectedValueException($value, 'string');
        }
        $value = (string) $value;
        if (null !== $constraint->normalizer) {
            $value = ($constraint->normalizer)($value);
        }
        if ($constraint->strict) {
            $this->validateStrict($value, $constraint);
            return;
        }
        $this->validateLoose($value, $constraint);
    }
    private function validateLoose(string $value, Uuid $constraint) : void {
        // Error priority:
        // 1. ERROR_INVALID_CHARACTERS
        // 2. ERROR_INVALID_HYPHEN_PLACEMENT
        // 3. ERROR_TOO_SHORT/ERROR_TOO_LONG
        // Trim any wrapping characters like [] or {} used by some legacy systems
        $trimmed = trim($value, '[]{}');
        // Position of the next expected hyphen
        $h = self::LOOSE_FIRST_HYPHEN_POSITION;
        // Expected length
        $l = self::LOOSE_MAX_LENGTH;
        for ($i = 0; $i < $l; ++$i) {
            // Check length
            if (!isset($trimmed[$i])) {
                $this->context
                    ->buildViolation($constraint->message)
                    ->setParameter('{{ value }}', $this->formatValue($value))
                    ->setCode(Uuid::TOO_SHORT_ERROR)
                    ->addViolation();
                return;
            }
            // Hyphens must occur every fifth position
            // xxxx-xxxx-xxxx-xxxx-xxxx-xxxx-xxxx-xxxx
            //     ^    ^    ^    ^    ^    ^    ^
            if ('-' === $trimmed[$i]) {
                if ($i !== $h) {
                    $this->context
                        ->buildViolation($constraint->message)
                        ->setParameter('{{ value }}', $this->formatValue($value))
                        ->setCode(Uuid::INVALID_HYPHEN_PLACEMENT_ERROR)
                        ->addViolation();
                    return;
                }
                $h += 5;
                continue;
            }
            // Missing hyphens are ignored
            if ($i === $h) {
                $h += 4;
                --$l;
            }
            // Check characters
            if (!ctype_xdigit($trimmed[$i])) {
                $this->context
                    ->buildViolation($constraint->message)
                    ->setParameter('{{ value }}', $this->formatValue($value))
                    ->setCode(Uuid::INVALID_CHARACTERS_ERROR)
                    ->addViolation();
                return;
            }
        }
        // Check length again
        if (isset($trimmed[$i])) {
            $this->context
                ->buildViolation($constraint->message)
                ->setParameter('{{ value }}', $this->formatValue($value))
                ->setCode(Uuid::TOO_LONG_ERROR)
                ->addViolation();
        }
    }
    private function validateStrict(string $value, Uuid $constraint) : void {
        // Error priority:
        // 1. ERROR_INVALID_CHARACTERS
        // 2. ERROR_INVALID_HYPHEN_PLACEMENT
        // 3. ERROR_TOO_SHORT/ERROR_TOO_LONG
        // 4. ERROR_INVALID_VERSION
        // 5. ERROR_INVALID_VARIANT
        // Position of the next expected hyphen
        $h = self::STRICT_FIRST_HYPHEN_POSITION;
        for ($i = 0; $i < self::STRICT_LENGTH; ++$i) {
            // Check length
            if (!isset($value[$i])) {
                $this->context
                    ->buildViolation($constraint->message)
                    ->setParameter('{{ value }}', $this->formatValue($value))
                    ->setCode(Uuid::TOO_SHORT_ERROR)
                    ->addViolation();
                return;
            }
            // Check hyphen placement
            // xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx
            //         ^    ^    ^    ^
            if ('-' === $value[$i]) {
                if ($i !== $h) {
                    $this->context
                        ->buildViolation($constraint->message)
                        ->setParameter('{{ value }}', $this->formatValue($value))
                        ->setCode(Uuid::INVALID_HYPHEN_PLACEMENT_ERROR)
                        ->addViolation();
                    return;
                }
                // xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx
                //                        ^
                if ($h < self::STRICT_LAST_HYPHEN_POSITION) {
                    $h += 5;
                }
                continue;
            }
            // Check characters
            if (!ctype_xdigit($value[$i])) {
                $this->context
                    ->buildViolation($constraint->message)
                    ->setParameter('{{ value }}', $this->formatValue($value))
                    ->setCode(Uuid::INVALID_CHARACTERS_ERROR)
                    ->addViolation();
                return;
            }
            // Missing hyphen
            if ($i === $h) {
                $this->context
                    ->buildViolation($constraint->message)
                    ->setParameter('{{ value }}', $this->formatValue($value))
                    ->setCode(Uuid::INVALID_HYPHEN_PLACEMENT_ERROR)
                    ->addViolation();
                return;
            }
        }
        // Check length again
        if (isset($value[$i])) {
            $this->context
                ->buildViolation($constraint->message)
                ->setParameter('{{ value }}', $this->formatValue($value))
                ->setCode(Uuid::TOO_LONG_ERROR)
                ->addViolation();
        }
        // Check version
        if (!\in_array($value[self::STRICT_VERSION_POSITION], $constraint->versions)) {
            $code = Uuid::TIME_BASED_VERSIONS === $constraint->versions ? Uuid::INVALID_TIME_BASED_VERSION_ERROR : Uuid::INVALID_VERSION_ERROR;
            $this->context
                ->buildViolation($constraint->message)
                ->setParameter('{{ value }}', $this->formatValue($value))
                ->setCode($code)
                ->addViolation();
        }
        // Check variant - first two bits must equal "10"
        //   0b10xx
        // & 0b1100 (12)
        // = 0b1000 (8)
        if (8 !== (hexdec($value[self::STRICT_VARIANT_POSITION]) & 12)) {
            $this->context
                ->buildViolation($constraint->message)
                ->setParameter('{{ value }}', $this->formatValue($value))
                ->setCode(Uuid::INVALID_VARIANT_ERROR)
                ->addViolation();
        }
    }

}