day02.sc

import common.loadPackets

case class Instruction(direction: String, amount: Int)

case class Position(horizontal: Int = 0, depth: Int = 0, aim: Int = 0) {
  def move: Instruction => Position = {
    case Instruction(direction, amount) =>
      direction match {
        case "up" => copy(depth = depth - amount)
        case "down" => copy(depth = depth + amount)
        case "forward" => copy(horizontal = horizontal + amount)
      }
  }

  def moveWithAim: Instruction => Position = {
    case Instruction(direction, amount) =>
      direction match {
        case "up" => copy(aim = aim - amount)
        case "down" => copy(aim = aim + amount)
        case "forward" => copy(horizontal = horizontal + amount, depth = depth + aim * amount)
      }
  }
}

val input = loadPackets(List("day02.txt"))
  .map(_.split(" ").toList)
  .map({ case List(a, b) => Instruction(a, b.toInt) })

val part1 = input.foldLeft(Position())((position, instruction) => position.move(instruction))
part1.horizontal * part1.depth

val part2 = input.foldLeft(Position())((position, instruction) => position.moveWithAim(instruction))
part2.horizontal * part2.depth