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();
  }

}