package aoc.day15

import aoc._
import scala.collection.mutable

val instructionStrings = lines.next().split(',').toSeq

// part 1

extension (s: String)
  def day15Hash =
    s.foldLeft(0)((a, b) => ((a + b) * 17) & 255)

def part1 =
  println(instructionStrings.map(_.day15Hash).sum)

// part 2

enum Ins:
  case Del(label: String)
  case Add(label: String, length: Int)

  def hash = this match
    case Del(label)         => label.day15Hash
    case Add(label, length) => label.day15Hash
import Ins._

object Parser extends CommonParser:
  val insKind =
    """[a-z]+""".r.flatMap { label =>
      ("-" ^^^ Del(label)) |
        ("=" ~ num ^^ { case _ ~ num => Add(label, num) })
    }
  def apply(s: String) = parse(insKind, s).get

val instructions = instructionStrings.map(Parser(_))

class Sim(ss: Seq[Ins]):
  private val boxes = (0 to 255).map(_ => mutable.ArrayBuffer.empty[Add]).toArray

  def handle(ins: Ins): Unit = ins match
    case a @ Add(label, length) =>
      boxes(ins.hash).indexWhere(_.label == label) match
        case -1  => boxes(ins.hash).append(a)
        case pos => boxes(ins.hash)(pos) = a
    case Del(label) => boxes(ins.hash).filterInPlace(_.label != label)

  ss.foreach(handle)

  def remain =
    boxes.toIterator.zipWithIndex.flatMap { (box, idx) =>
      box.toIterator.zipWithIndex.map { (add, pos) =>
        (idx + 1, pos + 1, add.length)
      }
    }

def part2 =
  println(Sim(instructions).remain.map(_ * _ * _).sum)

@main def Day15(part: Int) = part match
  case 1 => part1
  case 2 => part2