class NodeAccessControlHandler

class NodeAccessControlHandler extends EntityAccessControlHandler implements NodeAccessControlHandlerInterface, EntityHandlerInterface {
    
    /**
     * The node grant storage.
     *
     * @var \Drupal\node\NodeGrantDatabaseStorageInterface
     */
    protected $grantStorage;
    
    /**
     * Constructs a NodeAccessControlHandler object.
     *
     * @param \Drupal\Core\Entity\EntityTypeInterface $entity_type
     *   The entity type definition.
     * @param \Drupal\node\NodeGrantDatabaseStorageInterface $grant_storage
     *   The node grant storage.
     */
    public function __construct(EntityTypeInterface $entity_type, NodeGrantDatabaseStorageInterface $grant_storage) {
        parent::__construct($entity_type);
        $this->grantStorage = $grant_storage;
    }
    
    /**
     * {@inheritdoc}
     */
    public static function createInstance(ContainerInterface $container, EntityTypeInterface $entity_type) {
        return new static($entity_type, $container->get('node.grant_storage'));
    }
    
    /**
     * {@inheritdoc}
     */
    public function access(EntityInterface $entity, $operation, AccountInterface $account = NULL, $return_as_object = FALSE) {
        $account = $this->prepareUser($account);
        if ($account->hasPermission('bypass node access')) {
            $result = AccessResult::allowed()->cachePerPermissions();
            return $return_as_object ? $result : $result->isAllowed();
        }
        if (!$account->hasPermission('access content')) {
            $result = AccessResult::forbidden("The 'access content' permission is required.")->cachePerPermissions();
            return $return_as_object ? $result : $result->isAllowed();
        }
        $result = parent::access($entity, $operation, $account, TRUE)->cachePerPermissions();
        return $return_as_object ? $result : $result->isAllowed();
    }
    
    /**
     * {@inheritdoc}
     */
    public function createAccess($entity_bundle = NULL, AccountInterface $account = NULL, array $context = [], $return_as_object = FALSE) {
        $account = $this->prepareUser($account);
        if ($account->hasPermission('bypass node access')) {
            $result = AccessResult::allowed()->cachePerPermissions();
            return $return_as_object ? $result : $result->isAllowed();
        }
        if (!$account->hasPermission('access content')) {
            $result = AccessResult::forbidden("The 'access content' permission is required.")->cachePerPermissions();
            return $return_as_object ? $result : $result->isAllowed();
        }
        $result = parent::createAccess($entity_bundle, $account, $context, TRUE)->cachePerPermissions();
        return $return_as_object ? $result : $result->isAllowed();
    }
    
    /**
     * {@inheritdoc}
     */
    protected function checkAccess(EntityInterface $node, $operation, AccountInterface $account) {
        
        /** @var \Drupal\node\NodeInterface $node */
        // Fetch information from the node object if possible.
        $status = $node->isPublished();
        $uid = $node->getOwnerId();
        // Check if authors can view their own unpublished nodes.
        if ($operation === 'view' && !$status && $account->hasPermission('view own unpublished content') && $account->isAuthenticated() && $account->id() == $uid) {
            return AccessResult::allowed()->cachePerPermissions()
                ->cachePerUser()
                ->addCacheableDependency($node);
        }
        // Evaluate node grants.
        $access_result = $this->grantStorage
            ->access($node, $operation, $account);
        if ($operation === 'view' && $access_result instanceof RefinableCacheableDependencyInterface) {
            // Node variations can affect the access to the node. For instance, the
            // access result cache varies on the node's published status. Only the
            // 'view' node grant can currently be cached. The 'update' and 'delete'
            // grants are already marked as uncacheable in the node grant storage.
            // @see \Drupal\node\NodeGrantDatabaseStorage::access()
            $access_result->addCacheableDependency($node);
        }
        return $access_result;
    }
    
    /**
     * {@inheritdoc}
     */
    protected function checkCreateAccess(AccountInterface $account, array $context, $entity_bundle = NULL) {
        return AccessResult::allowedIf($account->hasPermission('create ' . $entity_bundle . ' content'))
            ->cachePerPermissions();
    }
    
    /**
     * {@inheritdoc}
     */
    protected function checkFieldAccess($operation, FieldDefinitionInterface $field_definition, AccountInterface $account, FieldItemListInterface $items = NULL) {
        // Only users with the administer nodes permission can edit administrative
        // fields.
        $administrative_fields = [
            'uid',
            'status',
            'created',
            'promote',
            'sticky',
        ];
        if ($operation == 'edit' && in_array($field_definition->getName(), $administrative_fields, TRUE)) {
            return AccessResult::allowedIfHasPermission($account, 'administer nodes');
        }
        // No user can change read only fields.
        $read_only_fields = [
            'revision_timestamp',
            'revision_uid',
        ];
        if ($operation == 'edit' && in_array($field_definition->getName(), $read_only_fields, TRUE)) {
            return AccessResult::forbidden();
        }
        // Users have access to the revision_log field either if they have
        // administrative permissions or if the new revision option is enabled.
        if ($operation == 'edit' && $field_definition->getName() == 'revision_log') {
            if ($account->hasPermission('administer nodes')) {
                return AccessResult::allowed()->cachePerPermissions();
            }
            return AccessResult::allowedIf($items->getEntity()->type->entity
                ->shouldCreateNewRevision())
                ->cachePerPermissions();
        }
        return parent::checkFieldAccess($operation, $field_definition, $account, $items);
    }
    
    /**
     * {@inheritdoc}
     */
    public function acquireGrants(NodeInterface $node) {
        $grants = $this->moduleHandler
            ->invokeAll('node_access_records', [
            $node,
        ]);
        // Let modules alter the grants.
        $this->moduleHandler
            ->alter('node_access_records', $grants, $node);
        // If no grants are set and the node is published, then use the default grant.
        if (empty($grants) && $node->isPublished()) {
            $grants[] = [
                'realm' => 'all',
                'gid' => 0,
                'grant_view' => 1,
                'grant_update' => 0,
                'grant_delete' => 0,
            ];
        }
        return $grants;
    }
    
    /**
     * {@inheritdoc}
     */
    public function writeGrants(NodeInterface $node, $delete = TRUE) {
        $grants = $this->acquireGrants($node);
        $this->grantStorage
            ->write($node, $grants, NULL, $delete);
    }
    
    /**
     * {@inheritdoc}
     */
    public function writeDefaultGrant() {
        $this->grantStorage
            ->writeDefault();
    }
    
    /**
     * {@inheritdoc}
     */
    public function deleteGrants() {
        $this->grantStorage
            ->delete();
    }
    
    /**
     * {@inheritdoc}
     */
    public function countGrants() {
        return $this->grantStorage
            ->count();
    }
    
    /**
     * {@inheritdoc}
     */
    public function checkAllGrants(AccountInterface $account) {
        return $this->grantStorage
            ->checkAll($account);
    }

}