class MediaConfigSubscriber

class MediaConfigSubscriber implements EventSubscriberInterface {
    
    /**
     * The route builder.
     *
     * @var \Drupal\Core\Routing\RouteBuilderInterface
     */
    protected $routeBuilder;
    
    /**
     * The cache tags invalidator.
     *
     * @var \Drupal\Core\Cache\CacheTagsInvalidatorInterface
     */
    protected $cacheTagsInvalidator;
    
    /**
     * The entity type manager.
     *
     * @var \Drupal\Core\Entity\EntityTypeManagerInterface
     */
    protected $entityTypeManager;
    
    /**
     * Constructs the MediaConfigSubscriber.
     *
     * @param \Drupal\Core\Routing\RouteBuilderInterface $router_builder
     *   The route builder.
     * @param \Drupal\Core\Cache\CacheTagsInvalidatorInterface $cache_tags_invalidator
     *   The cache tags invalidator.
     * @param \Drupal\Core\Entity\EntityTypeManagerInterface $entity_type_manager
     *   The entity type manager.
     */
    public function __construct(RouteBuilderInterface $router_builder, CacheTagsInvalidatorInterface $cache_tags_invalidator, EntityTypeManagerInterface $entity_type_manager) {
        $this->routeBuilder = $router_builder;
        $this->cacheTagsInvalidator = $cache_tags_invalidator;
        $this->entityTypeManager = $entity_type_manager;
    }
    
    /**
     * Updates entity type definitions and ensures routes are rebuilt when needed.
     *
     * @param \Drupal\Core\Config\ConfigCrudEvent $event
     *   The ConfigCrudEvent to process.
     */
    public function onSave(ConfigCrudEvent $event) {
        $saved_config = $event->getConfig();
        if ($saved_config->getName() === 'media.settings' && $event->isChanged('standalone_url')) {
            $this->cacheTagsInvalidator
                ->invalidateTags([
                // The configuration change triggers entity type definition changes,
                // which in turn triggers routes to appear or disappear.
                // @see media_entity_type_alter()
'entity_types',
                // The 'rendered' cache tag needs to be explicitly invalidated to ensure
                // that all links to Media entities are re-rendered. Ideally, this would
                // not be necessary; invalidating the 'entity_types' cache tag should be
                // sufficient. But that cache tag would then need to be on nearly
                // everything, resulting in excessive complexity. We prefer pragmatism.
'rendered',
            ]);
            // @todo Remove this when invalidating the 'entity_types' cache tag is
            // respected by the entity type plugin manager. See
            // https://www.drupal.org/project/drupal/issues/3001284 and
            // https://www.drupal.org/project/drupal/issues/3013659.
            $this->entityTypeManager
                ->clearCachedDefinitions();
            $this->routeBuilder
                ->setRebuildNeeded();
        }
    }
    
    /**
     * {@inheritdoc}
     */
    public static function getSubscribedEvents() : array {
        $events[ConfigEvents::SAVE][] = [
            'onSave',
        ];
        return $events;
    }

}