Speed1.scala

package Speed

case class World(containers: Map[Symbol, Container]) {
  def getAmount(key: Symbol): Double = {
    containers(key).group.amountPerContainer
  }

  def addWater(key: Symbol, amount: Double): World = {
    val group = containers(key).group
    val members = group.members
    val amountPerContainer = amount / members.size
    val group1 = group.copy(amountPerContainer = group.amountPerContainer + amountPerContainer)

    World(members.foldLeft(containers){ (containers, member) =>
      containers.updated(member, Container(group1))
    })
  }

  def connetTo(key1: Symbol, key2: Symbol): World = {
    val group1 = containers(key1).group
    val group2 = containers(key2).group
    if (group1 == group2)  this
    else {
      val size1: Int = group1.members.size
      val size2: Int = group2.members.size
      val tot1: Double = group1.amountPerContainer * size1
      val tot2: Double = group2.amountPerContainer * size2
      val newAmount: Double = (tot1 + tot2) / (size1 + size2)
      val newGroup: Group = Group(newAmount, group1.members ++ group2.members)
      World(newGroup.members.foldLeft(containers){ (containers, member) =>
        containers.updated(member, Container(newGroup))
      })
    }
  }
}

case class Container(group: Group)

object Container {
  def apply(name: Symbol): Container = Container(Group(0.0, Set(name)))
}

case class Group(amountPerContainer: Double, members: Set[Symbol])

object Speed1 extends App {
  val world = World(Map(
    'a -> Container('a),
    'b -> Container('b),
    'c -> Container('c),
    'd -> Container('d),
  ))

  val world1 = world
    .addWater('a, 12)
    .addWater('d, 8)
    .connetTo('a, 'b)
    .connetTo('b, 'c)

  println(world1)
}