abstract class Manufacturer {
  def build(carType: String): Car
}

class UKManufacturer extends Manufacturer {
  override def build(carType: String): Car = {
    val car: Car = carType match {
      case "convertible" => new Convertible
      case "family"      => new Family
      case "sports"      => new Sports
      case _ => throw new IllegalArgumentException("Unknown car type: " + carType)
    }
    car.temperatureScale = "Celsius"
    car.driverSide = "left"
    car
  }
}

class USManufacturer extends Manufacturer {
  override def build(carType: String): Car = {
    val car: Car = carType match {
      case "convertible" => new Convertible
      case "family"      => new Family
      case "sports"      => new Sports
      case _ => throw new IllegalArgumentException("Unknown car type: " + carType)
    }
    car.temperatureScale = "Fahrenheit"
    car.driverSide = "right"
    car
  }
}

object GymStandings {
  private var scores = Map.empty[GymEquipment, Int]

  def record(e: GymEquipment, calories: Int): Unit = {
    scores = scores.updated(e, calories)
  }

  def remove(e: GymEquipment): Unit = {
    scores = scores - e
  }

  def leaders: List[(GymEquipment, Int)] = {
    if (scores.isEmpty) Nil
    else {
      val best = scores.values.max
      scores.toList.filter { case (_, score) => score == best }
        .sortBy { case (equipment, _) => equipment.name }
    }
  }
}

class Performance(e: GymEquipment) extends Functionality {
  private def calories: Int =
    ((e.age - e.weight + e.heartRate) * e.time) / 10

  e.addFunctionality(this)
  GymStandings.record(e, calories)

  def update(): Unit = {
    val current = calories
    GymStandings.record(e, current)
    println("Your current performance is: " + current + " calories burned.")
  }
}

def cards: List[Int] = _cards
def cards_=(cs: List[Int]): Unit = { _cards = cs }
def visibleValue: Int = _visibleValue
def visibleValue_=(v: Int): Unit = { _visibleValue = v }

class Regular extends Player {
  def play(visibleCards: List[Int]): Boolean = {
    require(visibleCards.length == 1)
    val total = value
    if (total < 21 && total <= 21 - visibleCards.head) {
      hit
      true
    } else false
  }
}

class Optimistic extends Player {
  def play(visibleCards: List[Int]): Boolean = {
    if (value != 21) {
      hit
      true
    } else false
  }
}

class House extends Player {
  def play(visibleCards: List[Int]): Boolean = {
    val total = value
    if (total < 21 && visibleCards.forall(v => total <= 21 - v)) {
      hit
      true
    } else false
  }
}