class ViewsLocalTask

class ViewsLocalTask extends DeriverBase implements ContainerDeriverInterface {
    
    /**
     * The route provider.
     *
     * @var \Drupal\Core\Routing\RouteProviderInterface
     */
    protected $routeProvider;
    
    /**
     * The state key value store.
     *
     * @var \Drupal\Core\State\StateInterface
     */
    protected $state;
    
    /**
     * The view storage.
     *
     * @var \Drupal\Core\Entity\EntityStorageInterface
     */
    protected $viewStorage;
    
    /**
     * Constructs a \Drupal\views\Plugin\Derivative\ViewsLocalTask instance.
     *
     * @param \Drupal\Core\Routing\RouteProviderInterface $route_provider
     *   The route provider.
     * @param \Drupal\Core\State\StateInterface $state
     *   The state key value store.
     * @param \Drupal\Core\Entity\EntityStorageInterface $view_storage
     *   The view storage.
     */
    public function __construct(RouteProviderInterface $route_provider, StateInterface $state, EntityStorageInterface $view_storage) {
        $this->routeProvider = $route_provider;
        $this->state = $state;
        $this->viewStorage = $view_storage;
    }
    
    /**
     * {@inheritdoc}
     */
    public static function create(ContainerInterface $container, $base_plugin_id) {
        return new static($container->get('router.route_provider'), $container->get('state'), $container->get('entity_type.manager')
            ->getStorage('view'));
    }
    
    /**
     * {@inheritdoc}
     */
    public function getDerivativeDefinitions($base_plugin_definition) {
        $this->derivatives = [];
        $view_route_names = $this->state
            ->get('views.view_route_names');
        foreach ($this->getApplicableMenuViews() as $pair) {
            
            /** @var $executable \Drupal\views\ViewExecutable */
            list($view_id, $display_id) = $pair;
            $executable = $this->viewStorage
                ->load($view_id)
                ->getExecutable();
            $executable->setDisplay($display_id);
            $menu = $executable->display_handler
                ->getOption('menu');
            if (in_array($menu['type'], [
                'tab',
                'default tab',
            ])) {
                $plugin_id = 'view.' . $executable->storage
                    ->id() . '.' . $display_id;
                $route_name = $view_route_names[$executable->storage
                    ->id() . '.' . $display_id];
                // Don't add a local task for views which override existing routes.
                // @todo Alternative it could just change the existing entry.
                if ($route_name != $plugin_id) {
                    continue;
                }
                $this->derivatives[$plugin_id] = [
                    'route_name' => $route_name,
                    'weight' => $menu['weight'],
                    'title' => $menu['title'],
                ] + $base_plugin_definition;
                // Default local tasks have themselves as root tab.
                if ($menu['type'] == 'default tab') {
                    $this->derivatives[$plugin_id]['base_route'] = $route_name;
                }
            }
        }
        return $this->derivatives;
    }
    
    /**
     * Alters base_route and parent_id into the views local tasks.
     */
    public function alterLocalTasks(&$local_tasks) {
        $view_route_names = $this->state
            ->get('views.view_route_names');
        foreach ($this->getApplicableMenuViews() as $pair) {
            list($view_id, $display_id) = $pair;
            
            /** @var $executable \Drupal\views\ViewExecutable */
            $executable = $this->viewStorage
                ->load($view_id)
                ->getExecutable();
            $executable->setDisplay($display_id);
            $menu = $executable->display_handler
                ->getOption('menu');
            // We already have set the base_route for default tabs.
            if (in_array($menu['type'], [
                'tab',
            ])) {
                $plugin_id = 'view.' . $executable->storage
                    ->id() . '.' . $display_id;
                $view_route_name = $view_route_names[$executable->storage
                    ->id() . '.' . $display_id];
                // Don't add a local task for views which override existing routes.
                if ($view_route_name != $plugin_id) {
                    unset($local_tasks[$plugin_id]);
                    continue;
                }
                // Find out the parent route.
                // @todo Find out how to find both the root and parent tab.
                $path = $executable->display_handler
                    ->getPath();
                $split = explode('/', $path);
                array_pop($split);
                $path = implode('/', $split);
                $pattern = '/' . str_replace('%', '{}', $path);
                if ($routes = $this->routeProvider
                    ->getRoutesByPattern($pattern)) {
                    foreach ($routes->all() as $name => $route) {
                        $local_tasks['views_view:' . $plugin_id]['base_route'] = $name;
                        // Skip after the first found route.
                        break;
                    }
                }
            }
        }
    }
    
    /**
     * Return a list of all views and display IDs that have a menu entry.
     *
     * @return array
     *   A list of arrays containing the $view and $display_id.
     * @code
     * array(
     *   array($view, $display_id),
     *   array($view, $display_id),
     * );
     * @endcode
     */
    protected function getApplicableMenuViews() {
        return Views::getApplicableViews('uses_menu_links');
    }

}