Scalaskel en scala

Change.scala

package models.scalaskel

import play.api.libs.json._
import play.api.Logger


case class Change(foo:Int, bar:Int, qix:Int, baz:Int) {
  def this() = this(0, 0, 0, 0)
  def this(change:Change, coin:Coin) = this(
    if (coin.isFoo) change.foo + 1 else change.foo,
    if (coin.isBar) change.bar + 1 else change.bar,
    if (coin.isQix) change.qix + 1 else change.qix,
    if (coin.isBaz) change.baz + 1 else change.baz
  )

  def toJson:JsObject = {
    val fields = Seq("foo" -> foo,
      "bar" -> bar,
      "qix" -> qix,
      "baz" -> baz).filter( value => value._2 != 0)

    return JsObject(fields.map(f => (f._1, JsNumber(f._2))))
  }

}

Coin.scala

package models.scalaskel


case class Coin(value:Int) {

  def canPay(centsToPay:Int):Boolean = centsToPay >= value

  def isFoo:Boolean = value == 1
  def isBar:Boolean = value == 7
  def isQix:Boolean = value == 11
  def isBaz:Boolean = value == 21

}

object Coin {
  def allCoin = Seq(
    Coin(1),
    Coin(7),
    Coin(11),
    Coin(21)
  )
}

Scalaskel.scala

package controllers

import models.scalaskel.{Coin, Change}
import play.api.mvc._
import play.api.libs.json._

object Scalaskel extends Controller {

  def calculate(cents: Int, currentChange: Option[Change], lastCoin: Coin): List[Change] = {
    if (cents == 0) {
      return List(currentChange).filter(change => change.isDefined).map(change => change.get)
    }


    var changes: List[Change] = List()

    Coin.allCoin.filter(aCoin => aCoin.value >= lastCoin.value && aCoin.canPay(cents)).foreach(
      aCoin => {
        val newChange = new Change(currentChange.getOrElse(new Change()), aCoin)

        changes = changes ::: calculate(cents - aCoin.value, Option(newChange), aCoin)
      }
    )

    return changes
  }


  def change(cents: Integer) = Action {
    val changes = calculate(cents, Option.empty, Coin(1))
    val jsonResult = changes.map(change => change.toJson)
    Ok(Json.toJson(jsonResult))
  }

}