function gauth_login_user_login_submit() {
  if (variable_get('gauth_login_client_id', FALSE)) {
    $info = libraries_load('google-api-php-client');
    if (!$info['loaded']) {
      drupal_set_message(t("Can't authenticate with google as library is missing check Status report or Readme for requirements"), 'error');
      return FALSE;
    }
    $client = new Google_Client();
    $client->setApplicationName("Google OAuth2");
    $client->setClientId(variable_get('gauth_login_client_id'));
    $client->setClientSecret(variable_get('gauth_login_client_secret'));
    $client->setRedirectUri(gauth_callback_url());
    $client->setDeveloperKey(variable_get('gauth_login_developer_key'));
    $scopes = gauth_google_services_scopes();
    $client->addScope($scopes['oauth2']);
    if (!isset($_SESSION['gauth_login_state'])) {
      $state = array(
        'src' => 'gauth_login',
        'hash' => md5(rand())
      );
      if (isset($_GET['destination'])) {
        $state['destination'] = $_GET['destination'];
        unset($_GET['destination']);
      }
    }
    else {
      $state = $_SESSION['gauth_login_state'];
    }
    $_SESSION['gauth_login_state'] = $state;
    $state = drupal_json_encode($state);
    $client->setState($state);

    $url = $client->createAuthUrl();
    if ($restrict_domain = variable_get('gauth_login_domain_restriction', FALSE)) {
      $url .= '&hd=' . $restrict_domain;
    }

    drupal_goto($url);
  }
  else {
    drupal_set_message(t('Gauth Login is not configured. Please contact site administrator'), 'error');
  }
}