class ToolbarSettingsForm

class ToolbarSettingsForm extends ConfigFormBase {
    
    /**
     * The menu link tree service.
     *
     * @var \Drupal\Core\Menu\MenuLinkTree
     */
    protected $menuLinkTree;
    
    /**
     * ToolbarSettingsForm constructor.
     *
     * @param \Drupal\Core\Config\ConfigFactoryInterface $config_factory
     *   The config factory.
     * @param \Drupal\Core\Menu\MenuLinkTreeInterface $menu_link_tree
     *   The menu link tree service.
     */
    public function __construct(ConfigFactoryInterface $config_factory, MenuLinkTreeInterface $menu_link_tree) {
        parent::__construct($config_factory);
        $this->menuLinkTree = $menu_link_tree;
    }
    
    /**
     * {@inheritdoc}
     */
    public static function create(ContainerInterface $container) {
        return new static($container->get('config.factory'), $container->get('menu.link_tree'));
    }
    
    /**
     * {@inheritdoc}
     */
    public function getFormId() {
        return 'devel_toolbar_settings_form';
    }
    
    /**
     * {@inheritdoc}
     */
    protected function getEditableConfigNames() {
        return [
            'devel.toolbar.settings',
        ];
    }
    
    /**
     * {@inheritdoc}
     */
    public function buildForm(array $form, FormStateInterface $form_state) {
        $config = $this->config('devel.toolbar.settings');
        $form['toolbar_items'] = [
            '#type' => 'checkboxes',
            '#title' => $this->t('Menu items always visible'),
            '#options' => $this->getLinkLabels(),
            '#default_value' => $config->get('toolbar_items') ?: [],
            '#required' => TRUE,
            '#description' => $this->t('Select the menu items always visible in devel toolbar tray. All the items not selected in this list will be visible only when the toolbar orientation is vertical.'),
        ];
        return parent::buildForm($form, $form_state);
    }
    
    /**
     * {@inheritdoc}
     */
    public function submitForm(array &$form, FormStateInterface $form_state) {
        $values = $form_state->getValues();
        $toolbar_items = array_keys(array_filter($values['toolbar_items']));
        $this->config('devel.toolbar.settings')
            ->set('toolbar_items', $toolbar_items)
            ->save();
        parent::submitForm($form, $form_state);
    }
    
    /**
     * Provides an array of available menu items.
     *
     * @return array
     *   Associative array of devel menu item labels keyed by plugin ID.
     */
    protected function getLinkLabels() {
        $options = [];
        $parameters = new MenuTreeParameters();
        $parameters->onlyEnabledLinks()
            ->setTopLevelOnly();
        $tree = $this->menuLinkTree
            ->load('devel', $parameters);
        foreach ($tree as $element) {
            $link = $element->link;
            $options[$link->getPluginId()] = $link->getTitle();
        }
        asort($options);
        return $options;
    }

}