Alarm.scala

package com.ereactive.examples.akka.alarm

import akka.actor.typed.{ActorRef, Behavior}
import akka.actor.typed.scaladsl.Behaviors
import com.ereactive.examples.akka.alarm.Alarm._

class Alarm {
  def anAlarm[S <: AlarmState](pinCode: Int, state: S = InactiveAlarm)
  : Behavior[AlarmCommand] =
    Behaviors.receiveMessage {
      case ActivateAlarm(`pinCode`) =>
        anAlarm(pinCode, ActivateAlarm)
      case DeactivateAlarm(`pinCode`) =>
        anAlarm(pinCode, InactiveAlarm)
      case GetAlarmState(replyTo) =>
        replyTo ! state
        Behaviors.same
      case LockAlarm(times) =>
        val securityPinCode = ??? // get it from a database
        lockedAlarm(securityPinCode) // doesn't compile
    }

  def lockedAlarm(securityPinCode: Int): Behavior[UnlockedAlarm] =
    Behaviors.receive { (ctx, msg) => msg match {
      case UnlockedAlarm(`securityPinCode`, newPinCode, replyTo) =>
        replyTo ! InactiveAlarm(newPinCode)
        anAlarm(newPinCode, InactiveAlarm) // doesn't compile
    }}
}

object Alarm {
  sealed trait AlarmCommand
  case class ActivateAlarm(pinCode: Int) extends AlarmCommand
  case class DeactivateAlarm(pinCode: Int) extends AlarmCommand
  case class GetAlarmState(replyTo: ActorRef[AlarmState]) extends AlarmCommand
  case class LockAlarm(incorrectPinCodeTimes: Int) extends AlarmCommand
  case class UnlockedAlarm(securityPinCode: Int, newPinCode: Int, replyTo: ActorRef[InactiveAlarm.type]) extends AlarmCommand

  sealed trait AlarmState
  case object ActiveAlarm extends AlarmState
  case object InactiveAlarm extends AlarmState
  case object LockedAlarm extends AlarmState
}