class ValidKeysConstraintValidator

class ValidKeysConstraintValidator extends ConstraintValidator {
    
    /**
     * {@inheritdoc}
     */
    public function validate(mixed $value, Constraint $constraint) {
        assert($constraint instanceof ValidKeysConstraint);
        if (!is_array($value)) {
            // If the value is NULL, then the `NotNull` constraint validator will
            // set the appropriate validation error message.
            // @see \Drupal\Core\Validation\Plugin\Validation\Constraint\NotNullConstraintValidator
            if ($value === NULL) {
                return;
            }
            throw new UnexpectedTypeException($value, 'array');
        }
        // Indexed arrays are invalid by definition. array_is_list() returns TRUE
        // for empty arrays, so only do this check if $value is not empty.
        if ($value && array_is_list($value)) {
            $this->context
                ->addViolation($constraint->indexedArrayMessage);
            return;
        }
        $mapping = $this->context
            ->getObject();
        assert($mapping instanceof Mapping);
        $resolved_type = $mapping->getDataDefinition()
            ->getDataType();
        $valid_keys = $constraint->getAllowedKeys($this->context);
        $dynamically_valid_keys = $mapping->getDynamicallyValidKeys();
        $all_dynamically_valid_keys = array_merge(...array_values($dynamically_valid_keys));
        // Statically valid: keys that are valid for all possible types matching the
        // type definition of this mapping.
        // For example, `block.block.*:settings` has the following statically valid
        // keys: id, label, label_display, provider, status, info, view_mode and
        // context_mapping.
        // @see \Drupal\KernelTests\Config\Schema\MappingTest::providerMappingInterpretation()
        $invalid_keys = array_diff(array_keys($value), $valid_keys, $all_dynamically_valid_keys);
        foreach ($invalid_keys as $key) {
            $this->context
                ->buildViolation($constraint->invalidKeyMessage)
                ->setParameter('@key', $key)
                ->atPath((string) $key)
                ->setInvalidValue($key)
                ->addViolation();
        }
        // Dynamically valid: keys that are valid not for all possible types, but
        // for the actually resolved type definition of this mapping (in addition to
        // the statically valid keys).
        // @see \Drupal\Core\Config\Schema\Mapping::getDynamicallyValidKeys()
        if (!empty($all_dynamically_valid_keys)) {
            // For example, `block.block.*:settings` has the following dynamically valid
            // keys when the block plugin is `system_branding_block`:
            // - use_site_logo
            // - use_site_name
            // - use_site_slogan
            // @see \Drupal\KernelTests\Config\Schema\MappingTest::providerMappingInterpretation()
            $resolved_type_dynamically_valid_keys = $dynamically_valid_keys[$resolved_type] ?? [];
            // But if the `local_tasks_block` plugin is being used, then the
            // dynamically valid keys are:
            // - primary
            // - secondary
            // And for the `block.settings.search_form_block` plugin the dynamically
            // valid keys are:
            // - page_id
            // To help determine which keys are dynamically invalid, gather all keys
            // except for those for the actual resolved type of this mapping.
            // @see \Drupal\Core\Config\Schema\Mapping::getPossibleTypes()
            $other_types_valid_keys = array_diff($all_dynamically_valid_keys, $resolved_type_dynamically_valid_keys);
            $dynamically_invalid_keys = array_intersect(array_keys($value), $other_types_valid_keys);
            foreach ($dynamically_invalid_keys as $key) {
                $this->context
                    ->addViolation($constraint->dynamicInvalidKeyMessage, [
                    '@key' => $key,
                ] + self::getDynamicMessageParameters($mapping));
            }
        }
        // All keys are optional by default (meaning they can be omitted). This is
        // unintuitive and contradicts Drupal core's documentation.
        // @see https://www.drupal.org/node/2264179
        // To gradually evolve configuration schemas in the Drupal ecosystem to be
        // validatable, this needs to be clarified in a non-disruptive way. Any
        // config schema type definition — that is, a top-level entry in a
        // *.schema.yml file — can opt into stricter behavior, whereby a key is
        // required unless it specifies `requiredKey: false`, by adding
        // `FullyValidatable` as a top-level validation constraint.
        // @see https://www.drupal.org/node/3364108
        // @see https://www.drupal.org/node/3364109
        $root_type = $this->context
            ->getObject()
            ->getRoot()
            ->getDataDefinition()
            ->getDataType();
        $root_type_has_opted_in = FALSE;
        foreach ($this->context
            ->getObject()
            ->getRoot()
            ->getConstraints() as $c) {
            if ($c instanceof FullyValidatableConstraint) {
                $root_type_has_opted_in = TRUE;
                break;
            }
        }
        // Return early: do not generate validation errors for keys that are
        // required.
        if (!$root_type_has_opted_in) {
            return;
        }
        // If this is a dynamically typed property path, then not only must the
        // (absolute) root type be considered, but also the (relative) static root
        // type: the resolved type.
        // For example, `block.block.*:settings` has a dynamic type defined:
        // `block.settings.[%parent.plugin]`, but `block.block.*:plugin` does not.
        // Consequently, the value at the `plugin` property path depends only on the
        // `block.block.*` config schema type and hence only that config schema type
        // must have the `FullyValidatable` constraint, because it defines which
        // keys are required.
        // In contrast, the `block.block.*:settings` property path depends on
        // whichever dynamic type `block.settings.[%parent.plugin]` resolved to, to
        // be able to know which keys are required. Therefore that resolved type
        // determines which keys are required and whether it is fully validatable.
        // So for example the `block.settings.system_branding_block` config schema
        // type would also need to have the `FullyValidatable` constraint to
        // consider its schema-defined keys to be required:
        // - use_site_logo
        // - use_site_name
        // - use_site_slogan
        $static_type_root = TypedConfigManager::getStaticTypeRoot($this->context
            ->getObject());
        $static_type_root_type = $static_type_root->getDataDefinition()
            ->getDataType();
        if ($root_type !== $static_type_root_type) {
            $root_type_has_opted_in = FALSE;
            foreach ($static_type_root->getConstraints() as $c) {
                if ($c instanceof FullyValidatableConstraint) {
                    $root_type_has_opted_in = TRUE;
                    break;
                }
            }
            // Return early: do not generate validation errors for keys that are
            // required.
            if (!$root_type_has_opted_in) {
                return;
            }
        }
        $required_keys = array_intersect($mapping->getRequiredKeys(), $constraint->getAllowedKeys($this->context));
        // Statically required: same principle as for "statically valid" above, but
        // this time restricted to the subset of statically valid keys that do not
        // have `requiredKey: false`.
        $statically_required_keys = array_diff($required_keys, $all_dynamically_valid_keys);
        $missing_keys = array_diff($statically_required_keys, array_keys($value));
        foreach ($missing_keys as $key) {
            $this->context
                ->addViolation($constraint->missingRequiredKeyMessage, [
                '@key' => $key,
            ]);
        }
        // Dynamically required: same principle as for "dynamically valid" above,
        // but this time restricted to the subset of dynamically valid keys that do
        // not have `requiredKey: false`.
        $dynamically_required_keys = array_intersect($required_keys, $all_dynamically_valid_keys);
        $missing_dynamically_required_keys = array_diff($dynamically_required_keys, array_keys($value));
        foreach ($missing_dynamically_required_keys as $key) {
            $this->context
                ->addViolation($constraint->dynamicMissingRequiredKeyMessage, [
                '@key' => $key,
            ] + self::getDynamicMessageParameters($mapping));
        }
    }
    
    /**
     * Computes message parameters for dynamic type violations.
     *
     * @param \Drupal\Core\Config\Schema\Mapping $mapping
     *   A `type: mapping` instance, with values.
     *
     * @return array
     *   An array containing the following message parameters:
     *   - '@unresolved_dynamic_type': unresolved dynamic type
     *   - '@resolved_dynamic_type': resolved dynamic type
     *   - '@dynamic_type_property_path': (relative) property path of the condition
     *   - '@dynamic_type_property_value': value of the condition
     *
     * @see \Drupal\Core\Validation\Plugin\Validation\Constraint\ValidKeysConstraint::$dynamicInvalidKeyMessage
     */
    protected static function getDynamicMessageParameters(Mapping $mapping) : array {
        $definition = $mapping->getDataDefinition();
        assert($definition instanceof MapDataDefinition);
        $definition = $definition->toArray();
        assert(array_key_exists('mapping', $definition));
        // The original mapping definition is used to determine the unresolved type.
        // e.g. if $unresolved_type is …
        // 1. `editor.settings.[%parent.editor]`, then $resolved_type could perhaps
        //    `editor.settings.ckeditor5`, `editor.settings.unicorn`, etc.
        // 2. `block.settings.[%parent.plugin]`, then $resolved_type could perhaps
        //    be `block.settings.*`, `block.settings.system_branding_block`, etc.
        $parent_data_def = $mapping->getParent()
            ->getDataDefinition();
        $unresolved_type = match (TRUE) {    $parent_data_def instanceof MapDataDefinition => $parent_data_def->toArray()['mapping'][$mapping->getName()]['type'],
            $parent_data_def instanceof SequenceDataDefinition => $parent_data_def->toArray()['sequence']['type'],
            default => throw new \LogicException('Invalid config schema detected.'),
        
        };
        $resolved_type = $definition['type'];
        // $unresolved_type must be a dynamic type and the resolved type must be
        // different and not be dynamic.
        // @see \Drupal\Core\Config\TypedConfigManager::buildDataDefinition()
        assert(strpos($unresolved_type, ']'));
        assert($unresolved_type !== $resolved_type);
        assert(!strpos($resolved_type, ']'));
        $message_parameters = [
            '@unresolved_dynamic_type' => $unresolved_type,
            '@resolved_dynamic_type' => $resolved_type,
        ];
        $config = $mapping->getRoot();
        // Every config object is a mapping.
        assert($config instanceof Mapping);
        // Find the relative property path where this mapping starts.
        assert(str_starts_with($mapping->getPropertyPath(), $config->getName() . '.'));
        $property_path_mapping = substr($mapping->getPropertyPath(), strlen($config->getName()) + 1);
        // Extract the expressions stored in the dynamic type name.
        $matches = [];
        // @see \Drupal\Core\Config\TypedConfigManager::replaceDynamicTypeName()
        $result = preg_match("/\\[(.*)\\]/U", $unresolved_type, $matches);
        assert($result === 1);
        // @see \Drupal\Core\Config\TypedConfigManager::replaceExpression()
        $expression = $matches[1];
        // From the expression, extract the instructions for where to retrieve a value.
        $instructions = explode('.', $expression);
        // Determine the property path to the configuration key that has determined
        // this type.
        // @see \Drupal\Core\Config\TypedConfigManager::replaceExpression()
        $property_path_parts = explode('.', $property_path_mapping);
        // @see \Drupal\Core\Config\Schema\Mapping::getDynamicallyValidKeys()
        assert(!in_array('%type', $instructions, TRUE));
        // The %key instruction can only be used on its own. In this case, there is
        // no need to fetch a value, only the string that was used as the key is
        // responsible for determining the mapping type.
        if ($instructions === [
            '%key',
        ]) {
            $key = array_pop($property_path_parts);
            array_push($property_path_parts, '%key');
            $resolved_property_path = implode('.', $property_path_parts);
            return $message_parameters + [
                '@dynamic_type_property_path' => $resolved_property_path,
                '@dynamic_type_property_value' => $key,
            ];
        }
        // Do not replace variables, do not traverse the tree of data, but instead
        // resolve the property path that contains the value causing this particular
        // type to be selected.
        while ($instructions) {
            $instruction = array_shift($instructions);
            // Go up one level: remove the last part of the property path.
            if ($instruction === '%parent') {
                array_pop($property_path_parts);
            }
            else {
                array_push($property_path_parts, $instruction);
            }
        }
        $resolved_property_path = implode('.', $property_path_parts);
        $message_parameters += [
            '@dynamic_type_property_path' => $resolved_property_path,
        ];
        // Determine the corresponding value for that property path.
        $val = $config->get($resolved_property_path)
            ->getValue();
        // @see \Drupal\Core\Config\TypedConfigManager::replaceExpression()
        $val = is_bool($val) ? (int) $val : $val;
        return $message_parameters + [
            '@dynamic_type_property_value' => $val,
        ];
    }

}