class SearchPage

class SearchPage extends ConfigEntityBase implements SearchPageInterface, EntityWithPluginCollectionInterface {
    
    /**
     * The name (plugin ID) of the search page entity.
     *
     * @var string
     */
    protected $id;
    
    /**
     * The label of the search page entity.
     *
     * @var string
     */
    protected $label;
    
    /**
     * The configuration of the search page entity.
     *
     * @var array
     */
    protected $configuration = [];
    
    /**
     * The search plugin ID.
     *
     * @var string
     */
    protected $plugin;
    
    /**
     * The path this search page will appear upon.
     *
     * This value is appended to 'search/' when building the path.
     *
     * @var string
     */
    protected $path;
    
    /**
     * The weight of the search page.
     *
     * @var int
     */
    protected $weight;
    
    /**
     * The plugin collection that stores search plugins.
     *
     * @var \Drupal\search\Plugin\SearchPluginCollection
     */
    protected $pluginCollection;
    
    /**
     * {@inheritdoc}
     */
    public function getPlugin() {
        return $this->getPluginCollection()
            ->get($this->plugin);
    }
    
    /**
     * Encapsulates the creation of the search page's LazyPluginCollection.
     *
     * @return \Drupal\Component\Plugin\LazyPluginCollection
     *   The search page's plugin collection.
     */
    protected function getPluginCollection() {
        if (!$this->pluginCollection) {
            $this->pluginCollection = new SearchPluginCollection($this->searchPluginManager(), $this->plugin, $this->configuration, $this->id());
        }
        return $this->pluginCollection;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getPluginCollections() {
        return [
            'configuration' => $this->getPluginCollection(),
        ];
    }
    
    /**
     * {@inheritdoc}
     */
    public function setPlugin($plugin_id) {
        $this->plugin = $plugin_id;
        $this->getPluginCollection()
            ->addInstanceID($plugin_id);
    }
    
    /**
     * {@inheritdoc}
     */
    public function isIndexable() {
        return $this->status() && $this->getPlugin() instanceof SearchIndexingInterface;
    }
    
    /**
     * {@inheritdoc}
     */
    public function isDefaultSearch() {
        return $this->searchPageRepository()
            ->getDefaultSearchPage() == $this->id();
    }
    
    /**
     * {@inheritdoc}
     */
    public function getPath() {
        return $this->path;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getWeight() {
        return $this->weight;
    }
    
    /**
     * {@inheritdoc}
     */
    public function postCreate(EntityStorageInterface $storage) {
        parent::postCreate($storage);
        // @todo Use self::applyDefaultValue() once
        //   https://www.drupal.org/node/2004756 is in.
        if (!isset($this->weight)) {
            $this->weight = $this->isDefaultSearch() ? -10 : 0;
        }
    }
    
    /**
     * {@inheritdoc}
     */
    public function postSave(EntityStorageInterface $storage, $update = TRUE) {
        parent::postSave($storage, $update);
        $this->routeBuilder()
            ->setRebuildNeeded();
    }
    
    /**
     * {@inheritdoc}
     */
    public static function postDelete(EntityStorageInterface $storage, array $entities) {
        parent::postDelete($storage, $entities);
        $search_page_repository = \Drupal::service('search.search_page_repository');
        if (!$search_page_repository->isSearchActive()) {
            $search_page_repository->clearDefaultSearchPage();
        }
    }
    
    /**
     * {@inheritdoc}
     */
    public static function sort(ConfigEntityInterface $a, ConfigEntityInterface $b) {
        
        /** @var $a \Drupal\search\SearchPageInterface */
        
        /** @var $b \Drupal\search\SearchPageInterface */
        $a_status = (int) $a->status();
        $b_status = (int) $b->status();
        if ($a_status != $b_status) {
            return $a_status > $b_status ? -1 : 1;
        }
        return parent::sort($a, $b);
    }
    
    /**
     * Wraps the route builder.
     *
     * @return \Drupal\Core\Routing\RouteBuilderInterface
     *   An object for state storage.
     */
    protected function routeBuilder() {
        return \Drupal::service('router.builder');
    }
    
    /**
     * Wraps the config factory.
     *
     * @return \Drupal\Core\Config\ConfigFactoryInterface
     *   A config factory object.
     */
    protected function configFactory() {
        return \Drupal::service('config.factory');
    }
    
    /**
     * Wraps the search page repository.
     *
     * @return \Drupal\search\SearchPageRepositoryInterface
     *   A search page repository object.
     */
    protected function searchPageRepository() {
        return \Drupal::service('search.search_page_repository');
    }
    
    /**
     * Wraps the search plugin manager.
     *
     * @return \Drupal\Component\Plugin\PluginManagerInterface
     *   A search plugin manager object.
     */
    protected function searchPluginManager() {
        return \Drupal::service('plugin.manager.search');
    }

}