class EscalationPolicy implements Saga
{
    private int $escalationLevel = 0;

    public static function configureSaga(SagaConfiguration $saga)
    {
         $saga
           ->canBeStartedBy(CriticalAlert::class)
           ->correlatesWith(fn(CriticalAlert $event) => $event->alertId)
           ->correlatesWith(fn(AlertAcknoleged $event) => $event->alertId)
           ->correlatesWith(fn(AlertResolved $event) => $event->alertId);
    }

   public function whenWeSeeCriticalAlert(CriticalAlert $event, Context $context)
   {
       $context->send(new NotifyOnCallProviders())
       $context->scheduleTimeout(DateTimeInterval::createFromString('5 minutes'), new EscalationPeriod($event->alertId))
   }

   public function whenEscalationNotNeeded(AlertAcknoleged | AlertResolved $event, Context $context)
   {
       $context->completeSaga();
   }
   
   public function whenEscalationPeriodPassed(EscalationPeriod $event, Context $context)
   {
        $this->escalationLevel++;
        $context->send(new EscalateQuickly($this->escalationLevel, $event->alertId));
   }
}