class SystemMenuOffCanvasForm

class SystemMenuOffCanvasForm extends PluginFormBase implements ContainerInjectionInterface {
    use StringTranslationTrait;
    use RedirectDestinationTrait;
    
    /**
     * The plugin.
     *
     * @var \Drupal\Core\Block\BlockPluginInterface
     */
    protected $plugin;
    
    /**
     * The menu entity that the block uses and that will be edited in this form.
     *
     * @var \Drupal\system\MenuInterface
     */
    protected $menu;
    
    /**
     * @var \Drupal\Core\Entity\EntityStorageInterface
     */
    protected $menuStorage;
    
    /**
     * @var \Drupal\Core\Entity\EntityTypeManagerInterface
     */
    protected $entityTypeManager;
    
    /**
     * The config factory.
     *
     * @var \Drupal\Core\Config\ConfigFactoryInterface
     */
    protected $configFactory;
    
    /**
     * SystemMenuOffCanvasForm constructor.
     *
     * @param \Drupal\Core\Entity\EntityStorageInterface $menu_storage
     *   The menu storage handler.
     * @param \Drupal\Core\Entity\EntityTypeManagerInterface $entity_type_manager
     *   The entity type manager.
     * @param \Drupal\Core\StringTranslation\TranslationInterface $string_translation
     *   The string translation handler.
     * @param \Drupal\Core\Config\ConfigFactoryInterface $config_factory
     *   The config factory.
     */
    public function __construct(EntityStorageInterface $menu_storage, EntityTypeManagerInterface $entity_type_manager, TranslationInterface $string_translation, ConfigFactoryInterface $config_factory) {
        $this->menuStorage = $menu_storage;
        $this->entityTypeManager = $entity_type_manager;
        $this->stringTranslation = $string_translation;
        $this->configFactory = $config_factory;
    }
    
    /**
     * {@inheritdoc}
     */
    public static function create(ContainerInterface $container) {
        return new static($container->get('entity_type.manager')
            ->getStorage('menu'), $container->get('entity_type.manager'), $container->get('string_translation'), $container->get('config.factory'));
    }
    
    /**
     * {@inheritdoc}
     */
    public function buildConfigurationForm(array $form, FormStateInterface $form_state) {
        $form = $this->plugin
            ->buildConfigurationForm([], $form_state);
        // Move the menu levels section to the bottom.
        $form['menu_levels']['#weight'] = 100;
        $form['entity_form'] = [
            '#type' => 'details',
            '#title' => $this->t('Edit menu %label', [
                '%label' => $this->menu
                    ->label(),
            ]),
            '#open' => TRUE,
            '#access' => !$this->hasMenuOverrides() && $this->menu
                ->access('edit'),
        ];
        $form['entity_form'] += $this->getEntityForm($this->menu)
            ->buildForm([], $form_state);
        // Print the menu link titles as text instead of a link.
        if (!empty($form['entity_form']['links']['links'])) {
            foreach (Element::children($form['entity_form']['links']['links']) as $child) {
                $title = $form['entity_form']['links']['links'][$child]['title'][1]['#title'];
                $form['entity_form']['links']['links'][$child]['title'][1] = [
                    '#markup' => $title,
                ];
            }
        }
        // Change the header text.
        $form['entity_form']['links']['links']['#header'][0] = $this->t('Link');
        $form['entity_form']['links']['links']['#header'][1]['data'] = $this->t('On');
        // Remove the label, ID, description, and buttons from the entity form.
        unset($form['entity_form']['label'], $form['entity_form']['id'], $form['entity_form']['description'], $form['entity_form']['actions']);
        // Since the overview form is further nested than expected, update the
        // #parents. See \Drupal\menu_ui\MenuForm::form().
        $form_state->set('menu_overview_form_parents', [
            'settings',
            'entity_form',
            'links',
        ]);
        return $form;
    }
    
    /**
     * {@inheritdoc}
     */
    public function validateConfigurationForm(array &$form, FormStateInterface $form_state) {
        $this->plugin
            ->validateConfigurationForm($form, $form_state);
        if (!$this->hasMenuOverrides()) {
            $this->getEntityForm($this->menu)
                ->validateForm($form, $form_state);
        }
    }
    
    /**
     * {@inheritdoc}
     */
    public function submitConfigurationForm(array &$form, FormStateInterface $form_state) {
        $this->plugin
            ->submitConfigurationForm($form, $form_state);
        if (!$this->hasMenuOverrides()) {
            $this->getEntityForm($this->menu)
                ->submitForm($form, $form_state);
            $this->menu
                ->save();
        }
    }
    
    /**
     * Gets the entity form for this menu.
     *
     * @param \Drupal\system\MenuInterface $menu
     *   The menu entity.
     *
     * @return \Drupal\Core\Entity\EntityFormInterface
     *   The entity form.
     */
    protected function getEntityForm(MenuInterface $menu) {
        $entity_form = $this->entityTypeManager
            ->getFormObject('menu', 'edit');
        $entity_form->setEntity($menu);
        return $entity_form;
    }
    
    /**
     * {@inheritdoc}
     */
    public function setPlugin(PluginInspectionInterface $plugin) {
        $this->plugin = $plugin;
        $this->menu = $this->menuStorage
            ->loadOverrideFree($this->plugin
            ->getDerivativeId());
    }
    
    /**
     * Determines if the menu has configuration overrides.
     *
     * @return bool
     *   TRUE if the menu has configuration overrides, otherwise FALSE.
     */
    protected function hasMenuOverrides() {
        // @todo Replace the following with $this->menu->hasOverrides() in https://www.drupal.org/project/drupal/issues/2910353
        //   and remove this function.
        return $this->configFactory
            ->get($this->menu
            ->getEntityType()
            ->getConfigPrefix() . '.' . $this->menu
            ->id())
            ->hasOverrides();
    }

}