class EntityDataDefinition

class EntityDataDefinition extends ComplexDataDefinitionBase implements EntityDataDefinitionInterface {
    
    /**
     * Creates a new entity definition.
     *
     * @param string $entity_type_id
     *   (optional) The ID of the entity type, or NULL if the entity type is
     *   unknown. Defaults to NULL.
     * @param string $bundle
     *   (optional) The bundle of the entity type, or NULL if the bundle is
     *   unknown. Defaults to NULL.
     *
     * @return static
     */
    public static function create($entity_type_id = NULL, $bundle = NULL) {
        // If the entity type is known, use the derived definition.
        if (isset($entity_type_id)) {
            $data_type = "entity:{$entity_type_id}";
            // If a bundle was given, use the bundle-specific definition.
            if ($bundle) {
                $data_type .= ":{$bundle}";
            }
            // It's possible that the given entity type ID or bundle wasn't discovered
            // by the TypedData plugin manager and/or weren't created by the
            // EntityDeriver. In that case, this is a new definition and we'll just
            // create the definition from defaults by using an empty array.
            $values = \Drupal::typedDataManager()->getDefinition($data_type, FALSE);
            $definition = new static(is_array($values) ? $values : []);
            // Set the EntityType constraint using the given entity type ID.
            $definition->setEntityTypeId($entity_type_id);
            // If available, set the Bundle constraint.
            if ($bundle) {
                $definition->setBundles([
                    $bundle,
                ]);
            }
            return $definition;
        }
        return new static([]);
    }
    
    /**
     * {@inheritdoc}
     */
    public static function createFromDataType($data_type) {
        $parts = explode(':', $data_type);
        if ($parts[0] != 'entity') {
            throw new \InvalidArgumentException('Data type must be in the form of "entity:ENTITY_TYPE:BUNDLE."');
        }
        return static::create($parts[1] ?? NULL, $parts[2] ?? NULL);
    }
    
    /**
     * {@inheritdoc}
     */
    public function getPropertyDefinitions() {
        if (!isset($this->propertyDefinitions)) {
            if ($entity_type_id = $this->getEntityTypeId()) {
                // Return an empty array for entities that are not content entities.
                $entity_type_class = \Drupal::entityTypeManager()->getDefinition($entity_type_id)
                    ->getClass();
                if (!in_array('Drupal\\Core\\Entity\\FieldableEntityInterface', class_implements($entity_type_class))) {
                    $this->propertyDefinitions = [];
                }
                else {
                    // @todo: Add support for handling multiple bundles.
                    // See https://www.drupal.org/node/2169813.
                    $bundles = $this->getBundles();
                    if (is_array($bundles) && count($bundles) == 1) {
                        $this->propertyDefinitions = \Drupal::service('entity_field.manager')->getFieldDefinitions($entity_type_id, reset($bundles));
                    }
                    else {
                        $this->propertyDefinitions = \Drupal::service('entity_field.manager')->getBaseFieldDefinitions($entity_type_id);
                    }
                }
            }
            else {
                // No entity type given.
                $this->propertyDefinitions = [];
            }
        }
        return $this->propertyDefinitions;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getDataType() {
        $type = 'entity';
        if ($entity_type = $this->getEntityTypeId()) {
            $type .= ':' . $entity_type;
            // Append the bundle only if we know it for sure and it is not the default
            // bundle.
            if (($bundles = $this->getBundles()) && count($bundles) == 1) {
                $bundle = reset($bundles);
                if ($bundle != $entity_type) {
                    $type .= ':' . $bundle;
                }
            }
        }
        return $type;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getEntityTypeId() {
        return $this->definition['constraints']['EntityType'] ?? NULL;
    }
    
    /**
     * {@inheritdoc}
     */
    public function setEntityTypeId($entity_type_id) {
        return $this->addConstraint('EntityType', $entity_type_id);
    }
    
    /**
     * {@inheritdoc}
     */
    public function getBundles() {
        $bundle = $this->definition['constraints']['Bundle'] ?? NULL;
        return is_string($bundle) ? [
            $bundle,
        ] : $bundle;
    }
    
    /**
     * {@inheritdoc}
     */
    public function setBundles(array $bundles = NULL) {
        if (isset($bundles)) {
            $this->addConstraint('Bundle', $bundles);
        }
        else {
            // Remove the constraint.
            unset($this->definition['constraints']['Bundle']);
        }
        return $this;
    }

}