Fix OAuth2 authentication plugin based on review

src/Plugin/authentication/OAuth2ServerAuthentication.php

@@ -3,6 +3,7 @@
 namespace Drupal\restful\Plugin\authentication;
 
 use Drupal\Component\Plugin\PluginBase;
+use Drupal\restful\Exception\ServerConfigurationException;
 use Drupal\restful\Exception\UnauthorizedException;
 use Drupal\restful\Http\RequestInterface;
 use Drupal\restful\Plugin\ResourcePluginManager;
@@ -11,18 +12,30 @@
  * Authentication support for oauth2_server.
  *
  * @Authentication(
- *   id = "oauth2_auth",
+ *   id = "oauth2",
  *   label = "OAuth2 authentication",
  *   description = "Authenticate requests based on oauth2_server auth.",
  * )
  */
 class OAuth2ServerAuthentication extends Authentication {
 
+  /**
+   * The resource manager.
+   *
+   * @var \Drupal\restful\Resource\ResourceManagerInterface
+   */
+  protected $resourceManager;
+
+  public function __construct(array $configuration, $plugin_id, $plugin_definition) {
+    parent::__construct($configuration, $plugin_id, $plugin_definition);
+    $this->resourceManager = restful()->getResourceManager();
+  }
+
   /**
    * {@inheritdoc}
    */
   public function applies(RequestInterface $request) {
-    return module_exists('oauth2_server') && $this->getResourcePluginIdFromRequest();
+    return module_exists('oauth2_server') && $this->getOAuth2Info($request);
   }
 
   /**
@@ -31,38 +44,52 @@ public function applies(RequestInterface $request) {
   public function authenticate(RequestInterface $request) {
     $oauth2_info = $this->getOAuth2Info($request);
     if (!$oauth2_info) {
-      return NULL;
+      throw new ServerConfigurationException('The resource uses OAuth2 authentication but does not specify the OAuth2 server.');
     }
 
     $result = oauth2_server_check_access($oauth2_info['server'], $oauth2_info['scope']);
     if ($result instanceof \OAuth2\Response) {
       throw new UnauthorizedException($result->getResponseBody(), $result->getStatusCode());
     }
-    elseif (is_array($result) && !empty($result['user_id'])) {
-      return user_load($result['user_id']);
+    elseif (empty($result['user_id'])) {
+      return NULL;
     }
+    return user_load($result['user_id']);
   }
 
-//  protected function getOAuth2Info() {
-//    return [variable_get('oauth2_server_restful_server'), variable_get('oauth2_server_restful_scope')];
-//  }
-
-  protected function getOAuth2Info($request) {
+  /**
+   * Get OAuth2 information from the request.
+   *
+   * @param \Drupal\restful\Http\RequestInterface $request
+   *   The request.
+   *
+   * @return array|null
+   *   Simple associative array with the following keys:
+   *   - server: The OAuth2 server to authenticate against.
+   *   - scope: The scope required for the resource.
+   */
+  protected function getOAuth2Info(RequestInterface $request) {
     $plugin_id = $this->getResourcePluginIdFromRequest();
-    $plugin = ResourcePluginManager::create('cache', $request)->getDefinition($plugin_id);
+    $plugin_definition = ResourcePluginManager::create('cache', $request)->getDefinition($plugin_id);
 
-    $server = !empty($plugin['oauth2Server']) ? $plugin['oauth2Server'] : variable_get('oauth2_server_restful_server');
+    $server = !empty($plugin_definition['oauth2Server']) ? $plugin_definition['oauth2Server'] : variable_get('oauth2_server_restful_server');
     if (!$server) {
       return NULL;
     }
 
-    $scope = !empty($plugin['oauth2Scope']) ? $plugin['oauth2Scope'] : variable_get('oauth2_server_restful_scope');
+    $scope = !empty($plugin_definition['oauth2Scope']) ? $plugin_definition['oauth2Scope'] : variable_get('oauth2_server_restful_scope');
     return ['server' => $server, 'scope' =>$scope];
   }
 
+  /**
+   * Get the resource plugin id requested.
+   *
+   * @return null|string
+   *   The plugin id of the resource that was requested.
+   */
   protected function getResourcePluginIdFromRequest() {
-    $resource_name = restful()->getResourceManager()->getResourceIdFromRequest();
-    $version = restful()->getResourceManager()->getVersionFromRequest();
+    $resource_name = $this->resourceManager->getResourceIdFromRequest();
+    $version = $this->resourceManager->getVersionFromRequest();
 
     if (!$resource_name || !$version) {
       return NULL;