class CommentRenderController

class CommentRenderController extends EntityRenderController {

  /**
   * Overrides Drupal\Core\Entity\EntityRenderController::buildContent().
   *
   * In addition to modifying the content key on entities, this implementation
   * will also set the node key which all comments carry.
   */
  public function buildContent(array $entities = array(), $view_mode = 'full', $langcode = NULL) {
    $return = array();
    if (empty($entities)) {
      return $return;
    }

    // Attach user account.
    user_attach_accounts($entities);
    parent::buildContent($entities, $view_mode, $langcode);
    foreach ($entities as $entity) {
      $node = node_load($entity->nid);
      if (!$node) {
        throw new \InvalidArgumentException(t('Invalid node for comment.'));
      }
      $entity->content['#node'] = $node;
      $entity->content['#theme'] = 'comment__node_' . $node
        ->bundle();
      $entity->content['links'] = array(
        '#theme' => 'links__comment',
        '#pre_render' => array(
          'drupal_pre_render_links',
        ),
        '#attributes' => array(
          'class' => array(
            'links',
            'inline',
          ),
        ),
      );
      if (empty($entity->in_preview)) {
        $entity->content['links'][$this->entityType] = array(
          '#theme' => 'links__comment__comment',
          // The "node" property is specified to be present, so no need to check.
          '#links' => comment_links($entity, $node),
          '#attributes' => array(
            'class' => array(
              'links',
              'inline',
            ),
          ),
        );
      }
    }
  }

  /**
   * Overrides Drupal\Core\Entity\EntityRenderController::alterBuild().
   */
  protected function alterBuild(array &$build, EntityInterface $comment, $view_mode, $langcode = NULL) {
    parent::alterBuild($build, $comment, $view_mode, $langcode);
    if (empty($comment->in_preview)) {
      $prefix = '';
      $is_threaded = isset($comment->divs) && variable_get('comment_default_mode_' . $comment
        ->bundle(), COMMENT_MODE_THREADED) == COMMENT_MODE_THREADED;

      // Add 'new' anchor if needed.
      if (!empty($comment->first_new)) {
        $prefix .= "<a id=\"new\"></a>\n";
      }

      // Add indentation div or close open divs as needed.
      if ($is_threaded) {
        $prefix .= $comment->divs <= 0 ? str_repeat('</div>', abs($comment->divs)) : "\n" . '<div class="indented">';
      }

      // Add anchor for each comment.
      $prefix .= "<a id=\"comment-{$comment->cid}\"></a>\n";
      $build['#prefix'] = $prefix;

      // Close all open divs.
      if ($is_threaded && !empty($comment->divs_final)) {
        $build['#suffix'] = str_repeat('</div>', $comment->divs_final);
      }
    }
  }

}