public function getLoginUrl($params=array()) {
    $currentUrl = $this->getCurrentUrl();
    return $this->getUrl(
      'www',
      'dialog/oauth',
      array_merge(array(
        'client_id'     => $this->getAppId(),
        'redirect_uri'  => $currentUrl,
        'scope'         => ''
      ), $params)
    );
  }