class ResourceBase

abstract class ResourceBase extends PluginBase implements ContainerFactoryPluginInterface, ResourceInterface {
  
  /**
   * The available serialization formats.
   *
   * @var array
   */
  protected $serializerFormats = [];
  
  /**
   * A logger instance.
   *
   * @var \Psr\Log\LoggerInterface
   */
  protected $logger;
  
  /**
   * Constructs a Drupal\rest\Plugin\ResourceBase object.
   *
   * @param array $configuration
   *   A configuration array containing information about the plugin instance.
   * @param string $plugin_id
   *   The plugin_id for the plugin instance.
   * @param mixed $plugin_definition
   *   The plugin implementation definition.
   * @param array $serializer_formats
   *   The available serialization formats.
   * @param \Psr\Log\LoggerInterface $logger
   *   A logger instance.
   */
  public function __construct(array $configuration, $plugin_id, $plugin_definition, array $serializer_formats, LoggerInterface $logger) {
    parent::__construct($configuration, $plugin_id, $plugin_definition);
    $this->serializerFormats = $serializer_formats;
    $this->logger = $logger;
  }
  
  /**
   * {@inheritdoc}
   */
  public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) {
    return new static($configuration, $plugin_id, $plugin_definition, $container->getParameter('serializer.formats'), $container->get('logger.factory')
      ->get('rest'));
  }
  
  /**
   * Implements ResourceInterface::permissions().
   *
   * Every plugin operation method gets its own user permission. Example:
   * "restful delete entity:node" with the title "Access DELETE on Node
   * resource".
   */
  public function permissions() {
    $permissions = [];
    $definition = $this->getPluginDefinition();
    foreach ($this->availableMethods() as $method) {
      $lowered_method = strtolower($method);
      $permissions["restful {$lowered_method} {$this->pluginId}"] = [
        'title' => $this->t('Access @method on %label resource', [
          '@method' => $method,
          '%label' => $definition['label'],
        ]),
      ];
    }
    return $permissions;
  }
  
  /**
   * {@inheritdoc}
   */
  public function routes() {
    $collection = new RouteCollection();
    $definition = $this->getPluginDefinition();
    $canonical_path = $definition['uri_paths']['canonical'] ?? '/' . strtr($this->pluginId, ':', '/') . '/{id}';
    $create_path = $definition['uri_paths']['create'] ?? '/' . strtr($this->pluginId, ':', '/');
    $route_name = strtr($this->pluginId, ':', '.');
    $methods = $this->availableMethods();
    foreach ($methods as $method) {
      $path = $method === 'POST' ? $create_path : $canonical_path;
      $route = $this->getBaseRoute($path, $method);
      // Note that '_format' and '_content_type_format' route requirements are
      // added in ResourceRoutes::getRoutesForResourceConfig().
      $collection->add("{$route_name}.{$method}", $route);
    }
    return $collection;
  }
  
  /**
   * Provides predefined HTTP request methods.
   *
   * Plugins can override this method to provide additional custom request
   * methods.
   *
   * @return array
   *   The list of allowed HTTP request method strings.
   */
  protected function requestMethods() {
    return [
      'HEAD',
      'GET',
      'POST',
      'PUT',
      'DELETE',
      'TRACE',
      'OPTIONS',
      'CONNECT',
      'PATCH',
    ];
  }
  
  /**
   * {@inheritdoc}
   */
  public function availableMethods() {
    $methods = $this->requestMethods();
    $available = [];
    foreach ($methods as $method) {
      // Only expose methods where the HTTP request method exists on the plugin.
      if (method_exists($this, strtolower($method))) {
        $available[] = $method;
      }
    }
    return $available;
  }
  
  /**
   * Gets the base route for a particular method.
   *
   * @param string $canonical_path
   *   The canonical path for the resource.
   * @param string $method
   *   The HTTP method to be used for the route.
   *
   * @return \Symfony\Component\Routing\Route
   *   The created base route.
   */
  protected function getBaseRoute($canonical_path, $method) {
    return new Route($canonical_path, [
      '_controller' => 'Drupal\\rest\\RequestHandler::handle',
    ], $this->getBaseRouteRequirements($method), [], '', [], [
      $method,
    ]);
  }
  
  /**
   * Gets the base route requirements for a particular method.
   *
   * @param $method
   *   The HTTP method to be used for the route.
   *
   * @return array
   *   An array of requirements for parameters.
   */
  protected function getBaseRouteRequirements($method) {
    $lower_method = strtolower($method);
    // Every route MUST have requirements that result in the access manager
    // having access checks to check. If it does not, the route is made
    // inaccessible. So, we default to granting access to everyone. If a
    // permission exists, then we add that below. The access manager requires
    // that ALL access checks must grant access, so this still results in
    // correct behavior.
    $requirements = [
      '_access' => 'TRUE',
    ];
    // Only specify route requirements if the default permission exists. For any
    // more advanced route definition, resource plugins extending this base
    // class must override this method.
    $permission = "restful {$lower_method} {$this->pluginId}";
    if (isset($this->permissions()[$permission])) {
      $requirements['_permission'] = $permission;
    }
    return $requirements;
  }

}