class StatisticsLastCommentName

class StatisticsLastCommentName extends FieldPluginBase {
  
  /**
   * The users table.
   */
  protected $user_table;
  
  /**
   * The user name field.
   */
  protected $user_field;
  
  /**
   * {@inheritdoc}
   */
  public function query() {
    // last_comment_name only contains data if the user is anonymous. So we
    // have to join in a specially related user table.
    $this->ensureMyTable();
    // join 'users' to this table via vid
    $definition = [
      'table' => 'users_field_data',
      'field' => 'uid',
      'left_table' => 'comment_entity_statistics',
      'left_field' => 'last_comment_uid',
      'extra' => [
        [
          'field' => 'uid',
          'operator' => '!=',
          'value' => '0',
        ],
      ],
    ];
    $join = \Drupal::service('plugin.manager.views.join')->createInstance('standard', $definition);
    // nes_user alias so this can work with the sort handler, below.
    $this->user_table = $this->query
      ->ensureTable('ces_users', $this->relationship, $join);
    $this->field_alias = $this->query
      ->addField(NULL, "COALESCE({$this->user_table}.name, {$this->tableAlias}.{$this->field})", $this->tableAlias . '_' . $this->field);
    $this->user_field = $this->query
      ->addField($this->user_table, 'name');
    $this->uid = $this->query
      ->addField($this->tableAlias, 'last_comment_uid');
  }
  
  /**
   * {@inheritdoc}
   */
  protected function defineOptions() {
    $options = parent::defineOptions();
    $options['link_to_user'] = [
      'default' => TRUE,
    ];
    return $options;
  }
  
  /**
   * {@inheritdoc}
   */
  public function render(ResultRow $values) {
    if (!empty($this->options['link_to_user'])) {
      $account = User::create();
      $account->name = $this->getValue($values);
      $account->uid = $values->{$this->uid};
      $username = [
        '#theme' => 'username',
        '#account' => $account,
      ];
      return \Drupal::service('renderer')->render($username);
    }
    else {
      return $this->sanitizeValue($this->getValue($values));
    }
  }

}