import akka.actor._

object Fork {
  def props(id: Int): Props = Props(new Fork(id))
  final case class Take(philosopher: Int)
  final case class Release(philosopher: Int)
  final case class TookFork(fork: Int)
  final case class ReleasedFork(fork: Int)
}

class Fork(val id: Int) extends Actor {
  import Fork._

  object Status extends Enumeration {
    val FREE, TAKEN = Value
  }

  private var _status: Status.Value = Status.FREE
  private var _held_by: Int = -1

  def receive = {
    case Take(philosopher) if _status == Status.FREE => {
      println(s"tPhilosopher $philosopher takes fork $id.")
      take(philosopher)
      sender() ! TookFork(id)
      context.become(taken, false)
    }
    case Release(philosopher) if _status == Status.TAKEN && _held_by == philosopher => {
      println(s"tPhilosopher $philosopher puts down fork $id.")
      release()
      sender() ! ReleasedFork(id)
      context.unbecome()
    }
  }

  def take(philosopher: Int) = {
    _status  = Status.TAKEN
    _held_by = philosopher
  }

  def release() = {
    _status  = Status.FREE
    _held_by = -1
  }
}

override def unhandled(message: Any): Unit = {
  self forward message
}