protected function getTriggeredAlerts($period, $idSite)
 {
     $now = $this->getToday()->getDatetime();
     $model = new Model();
     $alerts = $model->getTriggeredAlertsForPeriod($period, $now, false);
     return array_filter($alerts, function ($alert) use($idSite) {
         return $idSite && (int) $alert['idsite'] === (int) $idSite && empty($alert['ts_last_sent']);
     });
 }