class CKEditor5ElementConstraintValidator

class CKEditor5ElementConstraintValidator extends ConstraintValidator {
    
    /**
     * {@inheritdoc}
     *
     * @throws \Symfony\Component\Validator\Exception\UnexpectedTypeException
     *   Thrown when the given constraint is not supported by this validator.
     */
    public function validate($element, $constraint) {
        if (!$constraint instanceof CKEditor5ElementConstraint) {
            throw new UnexpectedTypeException($constraint, __NAMESPACE__ . '\\CKEditor5Element');
        }
        $parsed = HTMLRestrictions::fromString($element);
        if ($parsed->allowsNothing() || count($parsed->getAllowedElements()) > 1 || $element !== $parsed->toCKEditor5ElementsArray()[0]) {
            $this->context
                ->buildViolation($constraint->message)
                ->setParameter('%provided_element', $element)
                ->addViolation();
        }
        // The optional "requiredAttributes" constraint property allows more
        // detailed validation.
        if (isset($constraint->requiredAttributes)) {
            $allowed_elements = $parsed->getAllowedElements();
            $tag = array_keys($allowed_elements)[0];
            $attribute_restrictions = $allowed_elements[$tag];
            assert(is_array($constraint->requiredAttributes));
            foreach ($constraint->requiredAttributes as $required_attribute) {
                // Validate attributeName.
                $required_attribute_name = $required_attribute['attributeName'];
                if (!is_array($attribute_restrictions) || !isset($attribute_restrictions[$required_attribute_name])) {
                    $this->context
                        ->buildViolation($constraint->missingRequiredAttributeMessage)
                        ->setParameter('@provided_element', $element)
                        ->setParameter('@required_attribute_name', $required_attribute_name)
                        ->addViolation();
                    continue;
                }
                $attribute_values = $attribute_restrictions[$required_attribute_name];
                // Validate minAttributeValueCount if specified.
                if (isset($required_attribute['minAttributeValueCount'])) {
                    $min_attribute_value_count = $required_attribute['minAttributeValueCount'];
                    if (!is_array($attribute_values) || count($attribute_values) < $min_attribute_value_count) {
                        $this->context
                            ->buildViolation($constraint->requiredAttributeMinValuesMessage)
                            ->setParameter('@provided_element', $element)
                            ->setParameter('@required_attribute_name', $required_attribute_name)
                            ->setParameter('@min_attribute_value_count', $min_attribute_value_count)
                            ->addViolation();
                        continue;
                    }
                }
            }
        }
    }

}