trait FieldableEntityNormalizerTrait

trait FieldableEntityNormalizerTrait {
    
    /**
     * The entity field manager.
     *
     * @var \Drupal\Core\Entity\EntityFieldManagerInterface
     */
    protected $entityFieldManager;
    
    /**
     * The entity type manager.
     *
     * @var \Drupal\Core\Entity\EntityTypeManagerInterface
     */
    protected $entityTypeManager;
    
    /**
     * The entity type repository.
     *
     * @var \Drupal\Core\Entity\EntityTypeRepositoryInterface
     */
    protected $entityTypeRepository;
    
    /**
     * Determines the entity type ID to denormalize as.
     *
     * @param string $class
     *   The entity type class to be denormalized to.
     * @param array $context
     *   The serialization context data.
     *
     * @return string
     *   The entity type ID.
     */
    protected function determineEntityTypeId($class, $context) {
        // Get the entity type ID while letting context override the $class param.
        return !empty($context['entity_type']) ? $context['entity_type'] : $this->getEntityTypeRepository()
            ->getEntityTypeFromClass($class);
    }
    
    /**
     * Gets the entity type definition.
     *
     * @param string $entity_type_id
     *   The entity type ID to load the definition for.
     *
     * @return \Drupal\Core\Entity\EntityTypeInterface
     *   The loaded entity type definition.
     *
     * @throws \Symfony\Component\Serializer\Exception\UnexpectedValueException
     */
    protected function getEntityTypeDefinition($entity_type_id) {
        
        /** @var \Drupal\Core\Entity\EntityTypeInterface $entity_type_definition */
        // Get the entity type definition.
        $entity_type_definition = $this->getEntityTypeManager()
            ->getDefinition($entity_type_id, FALSE);
        // Don't try to create an entity without an entity type id.
        if (!$entity_type_definition) {
            throw new UnexpectedValueException(sprintf('The specified entity type "%s" does not exist. A valid entity type is required for denormalization', $entity_type_id));
        }
        return $entity_type_definition;
    }
    
    /**
     * Denormalizes the bundle property so entity creation can use it.
     *
     * @param array $data
     *   The data being denormalized. The bundle information will be removed.
     * @param \Drupal\Core\Entity\EntityTypeInterface $entity_type_definition
     *   The entity type definition.
     *
     * @throws \Symfony\Component\Serializer\Exception\UnexpectedValueException
     *   If the bundle value is invalid or the bundle type is ineligible.
     *
     * @return array
     *   An array containing a single $bundle_key => $bundle_value pair.
     */
    protected function extractBundleData(array &$data, EntityTypeInterface $entity_type_definition) {
        $bundle_key = $entity_type_definition->getKey('bundle');
        // Get the base field definitions for this entity type.
        $base_field_definitions = $this->getEntityFieldManager()
            ->getBaseFieldDefinitions($entity_type_definition->id());
        // Get the ID key from the base field definition for the bundle key or
        // default to 'value'.
        $key_id = isset($base_field_definitions[$bundle_key]) ? $base_field_definitions[$bundle_key]->getFieldStorageDefinition()
            ->getMainPropertyName() : 'value';
        // Normalize the bundle if it is not explicitly set.
        $bundle_value = $data[$bundle_key][0][$key_id] ?? $data[$bundle_key] ?? NULL;
        // Unset the bundle from the data.
        unset($data[$bundle_key]);
        // Get the bundle entity type from the entity type definition.
        $bundle_type_id = $entity_type_definition->getBundleEntityType();
        $bundle_types = $bundle_type_id ? $this->getEntityTypeManager()
            ->getStorage($bundle_type_id)
            ->getQuery()
            ->accessCheck(TRUE)
            ->execute() : [];
        // Make sure a bundle has been provided.
        if (!is_string($bundle_value)) {
            throw new UnexpectedValueException(sprintf('Could not determine entity type bundle: "%s" field is missing.', $bundle_key));
        }
        // Make sure the submitted bundle is a valid bundle for the entity type.
        if ($bundle_types && !in_array($bundle_value, $bundle_types)) {
            throw new UnexpectedValueException(sprintf('"%s" is not a valid bundle type for denormalization.', $bundle_value));
        }
        return [
            $bundle_key => $bundle_value,
        ];
    }
    
    /**
     * Denormalizes entity data by denormalizing each field individually.
     *
     * @param array $data
     *   The data to denormalize.
     * @param \Drupal\Core\Entity\FieldableEntityInterface $entity
     *   The fieldable entity to set field values for.
     * @param string $format
     *   The serialization format.
     * @param array $context
     *   The context data.
     */
    protected function denormalizeFieldData(array $data, FieldableEntityInterface $entity, $format, array $context) {
        foreach ($data as $field_name => $field_data) {
            $field_item_list = $entity->get($field_name);
            // Remove any values that were set as a part of entity creation (e.g
            // uuid). If the incoming field data is set to an empty array, this will
            // also have the effect of emptying the field in REST module.
            $field_item_list->setValue([]);
            $field_item_list_class = get_class($field_item_list);
            if ($field_data) {
                // The field instance must be passed in the context so that the field
                // denormalizer can update field values for the parent entity.
                $context['target_instance'] = $field_item_list;
                $this->serializer
                    ->denormalize($field_data, $field_item_list_class, $format, $context);
            }
        }
    }
    
    /**
     * Returns the entity type repository.
     *
     * @return \Drupal\Core\Entity\EntityTypeRepositoryInterface
     *   The entity type repository.
     */
    protected function getEntityTypeRepository() {
        return $this->entityTypeRepository;
    }
    
    /**
     * Returns the entity field manager.
     *
     * @return \Drupal\Core\Entity\EntityFieldManagerInterface
     *   The entity field manager.
     */
    protected function getEntityFieldManager() {
        return $this->entityFieldManager;
    }
    
    /**
     * Returns the entity type manager.
     *
     * @return \Drupal\Core\Entity\EntityTypeManagerInterface
     *   The entity type manager.
     */
    protected function getEntityTypeManager() {
        return $this->entityTypeManager;
    }
    
    /**
     * Build the field item value using the incoming data.
     *
     * Most normalizers that extend this class can simply use this method to
     * construct the denormalized value without having to override denormalize()
     * and re-implementing its validation logic or its call to set the field
     * value.
     *
     * It's recommended to not override this and instead provide a (de)normalizer
     * at the DataType level.
     *
     * @param mixed $data
     *   The incoming data for this field item.
     * @param array $context
     *   The context passed into the Normalizer.
     *
     * @return mixed
     *   The value to use in \Drupal\Core\Field\FieldItemBase::setValue() or a
     *   subclass.
     */
    protected function constructValue($data, $context) {
        $field_item = $context['target_instance'];
        // Get the property definitions.
        assert($field_item instanceof FieldItemInterface);
        $field_definition = $field_item->getFieldDefinition();
        $item_definition = $field_definition->getItemDefinition();
        assert($item_definition instanceof FieldItemDataDefinitionInterface);
        $property_definitions = $item_definition->getPropertyDefinitions();
        $serialized_property_names = $this->getCustomSerializedPropertyNames($field_item);
        $denormalize_property = function ($property_name, $property_value, $property_value_class, $context) use ($serialized_property_names) {
            if ($this->serializer
                ->supportsDenormalization($property_value, $property_value_class, NULL, $context)) {
                return $this->serializer
                    ->denormalize($property_value, $property_value_class, NULL, $context);
            }
            else {
                if (in_array($property_name, $serialized_property_names, TRUE)) {
                    $property_value = serialize($property_value);
                }
                return $property_value;
            }
        };
        if (!is_array($data)) {
            $property_value = $data;
            $property_name = $item_definition->getMainPropertyName();
            $property_value_class = $property_definitions[$property_name]->getClass();
            return $denormalize_property($property_name, $property_value, $property_value_class, $context);
        }
        $data_internal = [];
        if (!empty($property_definitions)) {
            foreach ($property_definitions as $property_name => $property_definition) {
                // Not every property is required to be sent.
                if (!array_key_exists($property_name, $data)) {
                    continue;
                }
                $property_value = $data[$property_name];
                $property_value_class = $property_definition->getClass();
                $data_internal[$property_name] = $denormalize_property($property_name, $property_value, $property_value_class, $context);
            }
        }
        else {
            $data_internal = $data;
        }
        return $data_internal;
    }

}