class EntityBase

abstract class EntityBase implements EntityInterface {
    use RefinableCacheableDependencyTrait;
    use DependencySerializationTrait {
        __sleep as traitSleep;
    }
    
    /**
     * The entity type.
     *
     * @var string
     */
    protected $entityTypeId;
    
    /**
     * Boolean indicating whether the entity should be forced to be new.
     *
     * @var bool
     */
    protected $enforceIsNew;
    
    /**
     * A typed data object wrapping this entity.
     *
     * @var \Drupal\Core\TypedData\ComplexDataInterface
     */
    protected $typedData;
    
    /**
     * Constructs an Entity object.
     *
     * @param array $values
     *   An array of values to set, keyed by property name. If the entity type
     *   has bundles, the bundle key has to be specified.
     * @param string $entity_type
     *   The type of the entity to create.
     */
    public function __construct(array $values, $entity_type) {
        $this->entityTypeId = $entity_type;
        // Set initial values.
        foreach ($values as $key => $value) {
            $this->{$key} = $value;
        }
    }
    
    /**
     * Gets the entity type manager.
     *
     * @return \Drupal\Core\Entity\EntityTypeManagerInterface
     */
    protected function entityTypeManager() {
        return \Drupal::entityTypeManager();
    }
    
    /**
     * Gets the entity type bundle info service.
     *
     * @return \Drupal\Core\Entity\EntityTypeBundleInfoInterface
     */
    protected function entityTypeBundleInfo() {
        return \Drupal::service('entity_type.bundle.info');
    }
    
    /**
     * Gets the language manager.
     *
     * @return \Drupal\Core\Language\LanguageManagerInterface
     */
    protected function languageManager() {
        return \Drupal::languageManager();
    }
    
    /**
     * Gets the UUID generator.
     *
     * @return \Drupal\Component\Uuid\UuidInterface
     */
    protected function uuidGenerator() {
        return \Drupal::service('uuid');
    }
    
    /**
     * {@inheritdoc}
     */
    public function id() {
        return $this->id ?? NULL;
    }
    
    /**
     * {@inheritdoc}
     */
    public function uuid() {
        return $this->uuid ?? NULL;
    }
    
    /**
     * {@inheritdoc}
     */
    public function isNew() {
        return !empty($this->enforceIsNew) || !$this->id();
    }
    
    /**
     * {@inheritdoc}
     */
    public function enforceIsNew($value = TRUE) {
        $this->enforceIsNew = $value;
        return $this;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getEntityTypeId() {
        return $this->entityTypeId;
    }
    
    /**
     * {@inheritdoc}
     */
    public function bundle() {
        return $this->entityTypeId;
    }
    
    /**
     * {@inheritdoc}
     */
    public function label() {
        if (($label_key = $this->getEntityType()
            ->getKey('label')) && isset($this->{$label_key})) {
            return $this->{$label_key};
        }
    }
    
    /**
     * {@inheritdoc}
     */
    public function toUrl($rel = 'canonical', array $options = []) {
        if ($this->id() === NULL) {
            throw new EntityMalformedException(sprintf('The "%s" entity cannot have a URI as it does not have an ID', $this->getEntityTypeId()));
        }
        // The links array might contain URI templates set in annotations.
        $link_templates = $this->linkTemplates();
        // Links pointing to the current revision point to the actual entity. So
        // instead of using the 'revision' link, use the 'canonical' link.
        if ($rel === 'revision' && $this instanceof RevisionableInterface && $this->isDefaultRevision()) {
            $rel = 'canonical';
        }
        if (isset($link_templates[$rel])) {
            $route_parameters = $this->urlRouteParameters($rel);
            $route_name = "entity.{$this->entityTypeId}." . str_replace([
                '-',
                'drupal:',
            ], [
                '_',
                '',
            ], $rel);
            $uri = new Url($route_name, $route_parameters);
        }
        else {
            $bundle = $this->bundle();
            // A bundle-specific callback takes precedence over the generic one for
            // the entity type.
            $bundles = $this->entityTypeBundleInfo()
                ->getBundleInfo($this->getEntityTypeId());
            if (isset($bundles[$bundle]['uri_callback'])) {
                $uri_callback = $bundles[$bundle]['uri_callback'];
            }
            elseif ($entity_uri_callback = $this->getEntityType()
                ->getUriCallback()) {
                $uri_callback = $entity_uri_callback;
            }
            // Invoke the callback to get the URI. If there is no callback, use the
            // default URI format.
            if (isset($uri_callback) && is_callable($uri_callback)) {
                $uri = call_user_func($uri_callback, $this);
            }
            else {
                throw new UndefinedLinkTemplateException("No link template '{$rel}' found for the '{$this->getEntityTypeId()}' entity type");
            }
        }
        // Pass the entity data through as options, so that alter functions do not
        // need to look up this entity again.
        $uri->setOption('entity_type', $this->getEntityTypeId())
            ->setOption('entity', $this);
        // Display links by default based on the current language.
        // Link relations that do not require an existing entity should not be
        // affected by this entity's language, however.
        if (!in_array($rel, [
            'collection',
            'add-page',
            'add-form',
        ], TRUE)) {
            $options += [
                'language' => $this->language(),
            ];
        }
        $uri_options = $uri->getOptions();
        $uri_options += $options;
        return $uri->setOptions($uri_options);
    }
    
    /**
     * {@inheritdoc}
     */
    public function hasLinkTemplate($rel) {
        $link_templates = $this->linkTemplates();
        return isset($link_templates[$rel]);
    }
    
    /**
     * Gets an array link templates.
     *
     * @return array
     *   An array of link templates containing paths.
     */
    protected function linkTemplates() {
        return $this->getEntityType()
            ->getLinkTemplates();
    }
    
    /**
     * {@inheritdoc}
     */
    public function toLink($text = NULL, $rel = 'canonical', array $options = []) {
        if (!isset($text)) {
            $text = $this->label();
        }
        $url = $this->toUrl($rel);
        $options += $url->getOptions();
        $url->setOptions($options);
        return new Link($text, $url);
    }
    
    /**
     * Gets an array of placeholders for this entity.
     *
     * Individual entity classes may override this method to add additional
     * placeholders if desired. If so, they should be sure to replicate the
     * property caching logic.
     *
     * @param string $rel
     *   The link relationship type, for example: canonical or edit-form.
     *
     * @return array
     *   An array of URI placeholders.
     */
    protected function urlRouteParameters($rel) {
        $uri_route_parameters = [];
        if (!in_array($rel, [
            'collection',
            'add-page',
            'add-form',
        ], TRUE)) {
            // The entity ID is needed as a route parameter.
            $uri_route_parameters[$this->getEntityTypeId()] = $this->id();
        }
        if ($rel === 'add-form' && $this->getEntityType()
            ->hasKey('bundle')) {
            $parameter_name = $this->getEntityType()
                ->getBundleEntityType() ?: $this->getEntityType()
                ->getKey('bundle');
            $uri_route_parameters[$parameter_name] = $this->bundle();
        }
        if ($this instanceof RevisionableInterface && strpos($rel, 'revision') === 0) {
            $uri_route_parameters[$this->getEntityTypeId() . '_revision'] = $this->getRevisionId();
        }
        return $uri_route_parameters;
    }
    
    /**
     * {@inheritdoc}
     */
    public function uriRelationships() {
        return array_filter(array_keys($this->linkTemplates()), function ($link_relation_type) {
            // It's not guaranteed that every link relation type also has a
            // corresponding route. For some, additional modules or configuration may
            // be necessary. The interface demands that we only return supported URI
            // relationships.
            try {
                $this->toUrl($link_relation_type)
                    ->toString(TRUE)
                    ->getGeneratedUrl();
            } catch (RouteNotFoundException $e) {
                return FALSE;
            } catch (MissingMandatoryParametersException $e) {
                return FALSE;
            }
            return TRUE;
        });
    }
    
    /**
     * {@inheritdoc}
     */
    public function access($operation, AccountInterface $account = NULL, $return_as_object = FALSE) {
        if ($operation == 'create') {
            return $this->entityTypeManager()
                ->getAccessControlHandler($this->entityTypeId)
                ->createAccess($this->bundle(), $account, [], $return_as_object);
        }
        return $this->entityTypeManager()
            ->getAccessControlHandler($this->entityTypeId)
            ->access($this, $operation, $account, $return_as_object);
    }
    
    /**
     * {@inheritdoc}
     */
    public function language() {
        if ($key = $this->getEntityType()
            ->getKey('langcode')) {
            $langcode = $this->{$key};
            $language = $this->languageManager()
                ->getLanguage($langcode);
            if ($language) {
                return $language;
            }
        }
        // Make sure we return a proper language object.
        $langcode = !empty($this->langcode) ? $this->langcode : LanguageInterface::LANGCODE_NOT_SPECIFIED;
        $language = new Language([
            'id' => $langcode,
        ]);
        return $language;
    }
    
    /**
     * {@inheritdoc}
     */
    public function save() {
        $storage = $this->entityTypeManager()
            ->getStorage($this->entityTypeId);
        return $storage->save($this);
    }
    
    /**
     * {@inheritdoc}
     */
    public function delete() {
        if (!$this->isNew()) {
            $this->entityTypeManager()
                ->getStorage($this->entityTypeId)
                ->delete([
                $this->id() => $this,
            ]);
        }
    }
    
    /**
     * {@inheritdoc}
     */
    public function createDuplicate() {
        $duplicate = clone $this;
        $entity_type = $this->getEntityType();
        // Reset the entity ID and indicate that this is a new entity.
        $duplicate->{$entity_type->getKey('id')} = NULL;
        $duplicate->enforceIsNew();
        // Check if the entity type supports UUIDs and generate a new one if so.
        if ($entity_type->hasKey('uuid')) {
            $duplicate->{$entity_type->getKey('uuid')} = $this->uuidGenerator()
                ->generate();
        }
        return $duplicate;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getEntityType() {
        return $this->entityTypeManager()
            ->getDefinition($this->getEntityTypeId());
    }
    
    /**
     * {@inheritdoc}
     */
    public function preSave(EntityStorageInterface $storage) {
        // Check if this is an entity bundle.
        if ($this->getEntityType()
            ->getBundleOf()) {
            // Throw an exception if the bundle ID is longer than 32 characters.
            if (mb_strlen($this->id()) > EntityTypeInterface::BUNDLE_MAX_LENGTH) {
                throw new ConfigEntityIdLengthException("Attempt to create a bundle with an ID longer than " . EntityTypeInterface::BUNDLE_MAX_LENGTH . " characters: {$this->id}().");
            }
        }
    }
    
    /**
     * {@inheritdoc}
     */
    public function postSave(EntityStorageInterface $storage, $update = TRUE) {
        $this->invalidateTagsOnSave($update);
    }
    
    /**
     * {@inheritdoc}
     */
    public static function preCreate(EntityStorageInterface $storage, array &$values) {
    }
    
    /**
     * {@inheritdoc}
     */
    public function postCreate(EntityStorageInterface $storage) {
    }
    
    /**
     * {@inheritdoc}
     */
    public static function preDelete(EntityStorageInterface $storage, array $entities) {
    }
    
    /**
     * {@inheritdoc}
     */
    public static function postDelete(EntityStorageInterface $storage, array $entities) {
        static::invalidateTagsOnDelete($storage->getEntityType(), $entities);
    }
    
    /**
     * {@inheritdoc}
     */
    public static function postLoad(EntityStorageInterface $storage, array &$entities) {
    }
    
    /**
     * {@inheritdoc}
     */
    public function referencedEntities() {
        return [];
    }
    
    /**
     * {@inheritdoc}
     */
    public function getCacheContexts() {
        return $this->cacheContexts;
    }
    
    /**
     * The list cache tags to invalidate for this entity.
     *
     * @return string[]
     *   Set of list cache tags.
     */
    protected function getListCacheTagsToInvalidate() {
        $tags = $this->getEntityType()
            ->getListCacheTags();
        if ($this->getEntityType()
            ->hasKey('bundle')) {
            $tags[] = $this->getEntityTypeId() . '_list:' . $this->bundle();
        }
        return $tags;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getCacheTagsToInvalidate() {
        if ($this->isNew()) {
            return [];
        }
        return [
            $this->entityTypeId . ':' . $this->id(),
        ];
    }
    
    /**
     * {@inheritdoc}
     */
    public function getCacheTags() {
        if ($this->cacheTags) {
            return Cache::mergeTags($this->getCacheTagsToInvalidate(), $this->cacheTags);
        }
        return $this->getCacheTagsToInvalidate();
    }
    
    /**
     * {@inheritdoc}
     */
    public function getCacheMaxAge() {
        return $this->cacheMaxAge;
    }
    
    /**
     * {@inheritdoc}
     */
    public static function load($id) {
        $entity_type_repository = \Drupal::service('entity_type.repository');
        $entity_type_manager = \Drupal::entityTypeManager();
        $storage = $entity_type_manager->getStorage($entity_type_repository->getEntityTypeFromClass(static::class));
        return $storage->load($id);
    }
    
    /**
     * {@inheritdoc}
     */
    public static function loadMultiple(array $ids = NULL) {
        $entity_type_repository = \Drupal::service('entity_type.repository');
        $entity_type_manager = \Drupal::entityTypeManager();
        $storage = $entity_type_manager->getStorage($entity_type_repository->getEntityTypeFromClass(static::class));
        return $storage->loadMultiple($ids);
    }
    
    /**
     * {@inheritdoc}
     */
    public static function create(array $values = []) {
        $entity_type_repository = \Drupal::service('entity_type.repository');
        $entity_type_manager = \Drupal::entityTypeManager();
        $storage = $entity_type_manager->getStorage($entity_type_repository->getEntityTypeFromClass(static::class));
        return $storage->create($values);
    }
    
    /**
     * Invalidates an entity's cache tags upon save.
     *
     * @param bool $update
     *   TRUE if the entity has been updated, or FALSE if it has been inserted.
     */
    protected function invalidateTagsOnSave($update) {
        // An entity was created or updated: invalidate its list cache tags. (An
        // updated entity may start to appear in a listing because it now meets that
        // listing's filtering requirements. A newly created entity may start to
        // appear in listings because it did not exist before.)
        $tags = $this->getListCacheTagsToInvalidate();
        if ($this->hasLinkTemplate('canonical')) {
            // Creating or updating an entity may change a cached 403 or 404 response.
            $tags = Cache::mergeTags($tags, [
                '4xx-response',
            ]);
        }
        if ($update) {
            // An existing entity was updated, also invalidate its unique cache tag.
            $tags = Cache::mergeTags($tags, $this->getCacheTagsToInvalidate());
        }
        Cache::invalidateTags($tags);
    }
    
    /**
     * Invalidates an entity's cache tags upon delete.
     *
     * @param \Drupal\Core\Entity\EntityTypeInterface $entity_type
     *   The entity type definition.
     * @param \Drupal\Core\Entity\EntityInterface[] $entities
     *   An array of entities.
     */
    protected static function invalidateTagsOnDelete(EntityTypeInterface $entity_type, array $entities) {
        $tags = $entity_type->getListCacheTags();
        foreach ($entities as $entity) {
            // An entity was deleted: invalidate its own cache tag, but also its list
            // cache tags. (A deleted entity may cause changes in a paged list on
            // other pages than the one it's on. The one it's on is handled by its own
            // cache tag, but subsequent list pages would not be invalidated, hence we
            // must invalidate its list cache tags as well.)
            $tags = Cache::mergeTags($tags, $entity->getCacheTagsToInvalidate());
            $tags = Cache::mergeTags($tags, $entity->getListCacheTagsToInvalidate());
        }
        Cache::invalidateTags($tags);
    }
    
    /**
     * {@inheritdoc}
     */
    public function getOriginalId() {
        // By default, entities do not support renames and do not have original IDs.
        return NULL;
    }
    
    /**
     * {@inheritdoc}
     */
    public function setOriginalId($id) {
        // By default, entities do not support renames and do not have original IDs.
        // If the specified ID is anything except NULL, this should mark this entity
        // as no longer new.
        if ($id !== NULL) {
            $this->enforceIsNew(FALSE);
        }
        return $this;
    }
    
    /**
     * {@inheritdoc}
     */
    public function toArray() {
        return [];
    }
    
    /**
     * {@inheritdoc}
     */
    public function getTypedData() {
        if (!isset($this->typedData)) {
            $class = $this->getTypedDataClass();
            $this->typedData = $class::createFromEntity($this);
        }
        return $this->typedData;
    }
    
    /**
     * Returns the typed data class name for this entity.
     *
     * @return string
     *   The string representing the typed data class name.
     *
     * @see \Drupal\Core\Entity\Plugin\DataType\EntityAdapter
     */
    private function getTypedDataClass() : string {
        $typed_data_manager = \Drupal::typedDataManager();
        // Check more specific data types that could apply to this entity.
        $candidate_data_types = [
            "entity:{$this->getEntityTypeId()}:{$this->bundle()}",
            "entity:{$this->getEntityTypeId()}",
        ];
        foreach ($candidate_data_types as $candidate_data_type) {
            if ($typed_data_manager->hasDefinition($candidate_data_type)) {
                return $typed_data_manager->getDefinition($candidate_data_type)['class'];
            }
        }
        // Fall back to the generic entity definition.
        return $typed_data_manager->getDefinition('entity')['class'];
    }
    
    /**
     * {@inheritdoc}
     */
    public function __sleep() {
        $this->typedData = NULL;
        return $this->traitSleep();
    }
    
    /**
     * {@inheritdoc}
     */
    public function getConfigDependencyKey() {
        return $this->getEntityType()
            ->getConfigDependencyKey();
    }
    
    /**
     * {@inheritdoc}
     */
    public function getConfigDependencyName() {
        return $this->getEntityTypeId() . ':' . $this->bundle() . ':' . $this->uuid();
    }
    
    /**
     * {@inheritdoc}
     */
    public function getConfigTarget() {
        // For content entities, use the UUID for the config target identifier.
        // This ensures that references to the target can be deployed reliably.
        return $this->uuid();
    }

}