adam.scala

List(1, 2, 3, 4, 5) match {
  case (a1 @ 1) :: (a2 @ 2 ):: c :: _ => c
  case List(a1 @ 1, a2 @ 2, c) => c
  case _ => "no"
}


sealed trait State

case class WithOffer(offer: Offer) extends State
object WithOffer {
  implicit val hasOffer: HasOffer[WithOffer] = new HasOffer[WithOffer] {
    override def offer(s: WithOffer) = s.offer
  }
}



case class WithoutOffer() extends State
case class WithPartner(partnerName: String) extends State


case class WithOfferAndPartner(offer: Offer, partnerName: String) extends State
object WithOfferAndPartner {
  implicit val hasOffer: HasOffer[WithOfferAndPartner] = (s: WithOfferAndPartner) => s.offer
}


trait HasOffer[S] {
  def offer(s: S): Offer
}

case class Offer(id: Int)

case class Merchant[S <: State](name: String, state: S) {
  def addOfferBad(offer: Offer) = {
    Merchant[WithOffer](name, WithOffer(offer))
  }
  def addOffer2(offer: Offer)(implicit ev: S =:= WithoutOffer) = {
    Merchant[WithOffer](name, WithOffer(offer))
  }

  def getOfferSimple: Option[Offer] = ???
  def getOfferEq(implicit ev: S =:= WithOffer): Offer = {
    ???
  }
  def getOffer(implicit ev: HasOffer[S]): Offer = {
    ev.offer(state)
  }
}

object Merchant {
  // Bad, doesnt check current state of merchant
  def withOffer(name: String, offer: Offer) = {
    Merchant[WithOffer](name, WithOffer(offer))
  }

  def withoutOffer(name: String) = {
    Merchant[WithoutOffer](name, WithoutOffer())
  }


  def addOffer(merchant: Merchant[WithoutOffer], offer: Offer) = Merchant[WithOffer](merchant.name, WithOffer(offer))
}


def printOffer(merchat: Merchant[WithOffer]) = {
  println("offer: %s", merchat.state.offer)
}

//Merchant.withOffer("renan", Offer(1)).addOffer(Offer(1))
//Merchant.withOffer("renan", Offer(1)).addOffer2(Offer(1))
printOffer(Merchant.withOffer("renan", Offer(1)))
//printOffer(Merchant.withoutOffer("renan")) compile error


// Merchant[Int]("adam", 23)
Merchant.withOffer("renan", Offer(1)).getOffer