class NavigationUserBlock

final class NavigationUserBlock extends BlockBase {
  const NAVIGATION_LINKS_MENU = 'navigation-user-links';
  
  /**
   * {@inheritdoc}
   */
  public function build() : array {
    return [
      '#create_placeholder' => TRUE,
      '#lazy_builder' => [
        static::class . '::buildLinks',
        [
          $this->configuration['label'],
        ],
      ],
      '#cache' => [
        'keys' => [
          'navigation_user_block',
        ],
      ],
    ];
  }
  
  /**
   * Lazy builder callback.
   */
  public static function buildLinks(string $label) : array {
    $parameters = new MenuTreeParameters();
    $parameters->setMinDepth(0)
      ->setMaxDepth(2)
      ->onlyEnabledLinks();
    /** @var \Drupal\Core\Menu\MenuLinkTreeInterface $menu_tree */
    $menu_tree = \Drupal::service('navigation.menu_tree');
    $subtree = $menu_tree->load(static::NAVIGATION_LINKS_MENU, $parameters);
    // Load the current user so that they can be added as a cacheable dependency
    // of the final render array.
    $account = User::load(\Drupal::currentUser()->id());
    $menu_definition = [
      'menu_name' => static::NAVIGATION_LINKS_MENU,
      'route_name' => 'user.page',
      'route_parameters' => [],
      'title' => $account->getDisplayName(),
      'description' => '',
      'options' => [],
      'provider' => 'navigation',
      'enabled' => '1',
    ];
    // Create a parent link that serves as a wrapper.
    // If the menu is removed for any reason, this item shows a link to the
    // user profile page as a fallback.
    $link = MenuLinkDefault::create(\Drupal::getContainer(), [], 'navigation.user_links.user.wrapper', $menu_definition);
    $tree = new MenuLinkTreeElement($link, TRUE, 1, FALSE, $subtree);
    $manipulators = [
      [
        'callable' => 'menu.default_tree_manipulators:checkAccess',
      ],
      [
        'callable' => 'menu.default_tree_manipulators:generateIndexAndSort',
      ],
    ];
    $tree = $menu_tree->transform([
      $tree,
    ], $manipulators);
    $build = $menu_tree->build($tree);
    $build['#title'] = $label;
    $build['#cache']['contexts'][] = 'user';
    $cacheable_metadata = CacheableMetadata::createFromRenderArray($build);
    $cacheable_metadata->addCacheableDependency($account);
    $cacheable_metadata->applyTo($build);
    return $build;
  }

}