NodePreviewAccessCheck.php

<?php

namespace Drupal\node\Access;

use Drupal\Core\Entity\EntityTypeManagerInterface;
use Drupal\Core\Routing\Access\AccessInterface;
use Drupal\Core\Session\AccountInterface;
use Drupal\node\NodeInterface;

/**
 * Determines access to node previews.
 *
 * @ingroup node_access
 */
class NodePreviewAccessCheck implements AccessInterface {
    
    /**
     * The entity type manager service.
     *
     * @var \Drupal\Core\Entity\EntityTypeManagerInterface
     */
    protected $entityTypeManager;
    
    /**
     * Constructs an EntityCreateAccessCheck object.
     *
     * @param \Drupal\Core\Entity\EntityTypeManagerInterface $entity_type_manager
     *   The entity type manager service.
     */
    public function __construct(EntityTypeManagerInterface $entity_type_manager) {
        $this->entityTypeManager = $entity_type_manager;
    }
    
    /**
     * Checks access to the node preview page.
     *
     * @param \Drupal\Core\Session\AccountInterface $account
     *   The currently logged in account.
     * @param \Drupal\node\NodeInterface $node_preview
     *   The node that is being previewed.
     *
     * @return \Drupal\Core\Access\AccessResultInterface
     *   The access result.
     */
    public function access(AccountInterface $account, NodeInterface $node_preview) {
        if ($node_preview->isNew()) {
            $access_controller = $this->entityTypeManager
                ->getAccessControlHandler('node');
            return $access_controller->createAccess($node_preview->bundle(), $account, [], TRUE);
        }
        else {
            return $node_preview->access('update', $account, TRUE);
        }
    }

}