class BlockContentAccessControlHandler

class BlockContentAccessControlHandler extends EntityAccessControlHandler implements EntityHandlerInterface {
  
  /**
   * The event dispatcher.
   *
   * @var \Symfony\Contracts\EventDispatcher\EventDispatcherInterface
   */
  protected $eventDispatcher;
  
  /**
   * BlockContentAccessControlHandler constructor.
   *
   * @param \Drupal\Core\Entity\EntityTypeInterface $entity_type
   *   The entity type.
   * @param \Symfony\Contracts\EventDispatcher\EventDispatcherInterface $dispatcher
   *   The event dispatcher.
   */
  public function __construct(EntityTypeInterface $entity_type, EventDispatcherInterface $dispatcher) {
    parent::__construct($entity_type);
    $this->eventDispatcher = $dispatcher;
  }
  
  /**
   * {@inheritdoc}
   */
  public static function createInstance(ContainerInterface $container, EntityTypeInterface $entity_type) {
    return new static($entity_type, $container->get('event_dispatcher'));
  }
  
  /**
   * {@inheritdoc}
   */
  protected function checkAccess(EntityInterface $entity, $operation, AccountInterface $account) {
    if ($operation === 'view') {
      $access = AccessResult::allowedIf($entity->isPublished())
        ->orIf(AccessResult::allowedIfHasPermission($account, 'administer blocks'));
    }
    else {
      $access = parent::checkAccess($entity, $operation, $account);
    }
    // Add the entity as a cacheable dependency because access will at least be
    // determined by whether the block is reusable.
    $access->addCacheableDependency($entity);
    /** @var \Drupal\block_content\BlockContentInterface $entity */
    if ($entity->isReusable() === FALSE) {
      if (!$entity instanceof DependentAccessInterface) {
        throw new \LogicException("Non-reusable block entities must implement \\Drupal\\block_content\\Access\\DependentAccessInterface for access control.");
      }
      $dependency = $entity->getAccessDependency();
      if (empty($dependency)) {
        // If an access dependency has not been set let modules set one.
        $event = new BlockContentGetDependencyEvent($entity);
        $this->eventDispatcher
          ->dispatch($event, BlockContentEvents::BLOCK_CONTENT_GET_DEPENDENCY);
        $dependency = $event->getAccessDependency();
        if (empty($dependency)) {
          return AccessResult::forbidden("Non-reusable blocks must set an access dependency for access control.");
        }
      }
      /** @var \Drupal\Core\Entity\EntityInterface $dependency */
      $access = $access->andIf($dependency->access($operation, $account, TRUE));
    }
    return $access;
  }

}