class ToolbarHandler

class ToolbarHandler implements ContainerInjectionInterface, TrustedCallbackInterface {
    use StringTranslationTrait;
    
    /**
     * The menu link tree service.
     *
     * @var \Drupal\Core\Menu\MenuLinkTreeInterface
     */
    protected $menuLinkTree;
    
    /**
     * The devel toolbar config.
     *
     * @var \Drupal\Core\Config\ImmutableConfig
     */
    protected $config;
    
    /**
     * The current user.
     *
     * @var \Drupal\Core\Session\AccountProxyInterface
     */
    protected $account;
    
    /**
     * ToolbarHandler constructor.
     *
     * @param \Drupal\Core\Menu\MenuLinkTreeInterface $menu_link_tree
     *   The menu link tree service.
     * @param \Drupal\Core\Config\ConfigFactoryInterface $config_factory
     *   The config factory.
     * @param \Drupal\Core\Session\AccountProxyInterface $account
     *   The current user.
     */
    public function __construct(MenuLinkTreeInterface $menu_link_tree, ConfigFactoryInterface $config_factory, AccountProxyInterface $account) {
        $this->menuLinkTree = $menu_link_tree;
        $this->config = $config_factory->get('devel.toolbar.settings');
        $this->account = $account;
    }
    
    /**
     * {@inheritdoc}
     */
    public static function create(ContainerInterface $container) {
        return new static($container->get('toolbar.menu_tree'), $container->get('config.factory'), $container->get('current_user'));
    }
    
    /**
     * {@inheritdoc}
     */
    public static function trustedCallbacks() {
        return [
            'lazyBuilder',
        ];
    }
    
    /**
     * Hook bridge.
     *
     * @return array
     *   The devel toolbar items render array.
     *
     * @see hook_toolbar()
     */
    public function toolbar() {
        $items['devel'] = [
            '#cache' => [
                'contexts' => [
                    'user.permissions',
                ],
            ],
        ];
        if ($this->account
            ->hasPermission('access devel information')) {
            $items['devel'] += [
                '#type' => 'toolbar_item',
                '#weight' => 999,
                'tab' => [
                    '#type' => 'link',
                    '#title' => $this->t('Devel'),
                    '#url' => Url::fromRoute('devel.admin_settings'),
                    '#attributes' => [
                        'title' => $this->t('Development menu'),
                        'class' => [
                            'toolbar-icon',
                            'toolbar-icon-devel',
                        ],
                    ],
                ],
                'tray' => [
                    '#heading' => $this->t('Development menu'),
                    'devel_menu' => [
                        // Currently devel menu is uncacheable, so instead of poisoning the
                        // entire page cache we use a lazy builder.
                        // @see \Drupal\devel\Plugin\Menu\DestinationMenuLink
                        // @see \Drupal\devel\Plugin\Menu\RouteDetailMenuItem
'#lazy_builder' => [
                            ToolbarHandler::class . ':lazyBuilder',
                            [],
                        ],
                        // Force the creation of the placeholder instead of rely on the
                        // automatical placeholdering or otherwise the page results
                        // uncacheable when max-age 0 is bubbled up.
'#create_placeholder' => TRUE,
                    ],
                    'configuration' => [
                        '#type' => 'link',
                        '#title' => $this->t('Configure'),
                        '#url' => Url::fromRoute('devel.toolbar.settings_form'),
                        '#options' => [
                            'attributes' => [
                                'class' => [
                                    'edit-devel-toolbar',
                                ],
                            ],
                        ],
                    ],
                ],
                '#attached' => [
                    'library' => 'devel/devel-toolbar',
                ],
            ];
        }
        return $items;
    }
    
    /**
     * Lazy builder callback for the devel menu toolbar.
     *
     * @return array
     *   The renderable array rapresentation of the devel menu.
     */
    public function lazyBuilder() {
        $parameters = new MenuTreeParameters();
        $parameters->onlyEnabledLinks()
            ->setTopLevelOnly();
        $tree = $this->menuLinkTree
            ->load('devel', $parameters);
        $manipulators = [
            [
                'callable' => 'menu.default_tree_manipulators:checkAccess',
            ],
            [
                'callable' => 'menu.default_tree_manipulators:generateIndexAndSort',
            ],
            [
                'callable' => ToolbarHandler::class . ':processTree',
            ],
        ];
        $tree = $this->menuLinkTree
            ->transform($tree, $manipulators);
        $build = $this->menuLinkTree
            ->build($tree);
        CacheableMetadata::createFromRenderArray($build)->addCacheableDependency($this->config)
            ->applyTo($build);
        return $build;
    }
    
    /**
     * Adds toolbar-specific attributes to the menu link tree.
     *
     * @param \Drupal\Core\Menu\MenuLinkTreeElement[] $tree
     *   The menu link tree to manipulate.
     *
     * @return \Drupal\Core\Menu\MenuLinkTreeElement[]
     *   The manipulated menu link tree.
     */
    public function processTree(array $tree) {
        $visible_items = $this->config
            ->get('toolbar_items') ?: [];
        foreach ($tree as $element) {
            $plugin_id = $element->link
                ->getPluginId();
            if (!in_array($plugin_id, $visible_items)) {
                // Add a class that allow to hide the non prioritized menu items when
                // the toolbar has horizontal orientation.
                $element->options['attributes']['class'][] = 'toolbar-horizontal-item-hidden';
            }
        }
        return $tree;
    }

}