package be.vandewalleh.aoc.days

import be.vandewalleh.aoc.utils.input.Day
import be.vandewalleh.aoc.utils.input.Groups

private data class PlayedGame(val a: List<Int>, val b: List<Int>)

@Day(22)
class Day22(@Groups val input: List<List<String>>) {
    private val one = input[0].drop(1).map { it.toInt() }
    private val two = input[1].drop(1).map { it.toInt() }

    fun part1(): Long {
        val oneDeque = ArrayDeque(one)
        val twoDeque = ArrayDeque(two)

        while (oneDeque.isNotEmpty() && twoDeque.isNotEmpty()) {
            val a = oneDeque.removeFirst()
            val b = twoDeque.removeFirst()

            if (a > b) {
                oneDeque.addLast(a)
                oneDeque.addLast(b)
            } else {
                twoDeque.addLast(b)
                twoDeque.addLast(a)
            }
        }

        val deque = if (oneDeque.isEmpty()) twoDeque else oneDeque
        return deque.score()
    }

    private fun ArrayDeque<Int>.score() =
        asReversed().mapIndexed { index, value -> (index + 1).toLong() * value.toLong() }.sum()

    fun part2(): Long {
        val oneDeque = ArrayDeque(one)
        val twoDeque = ArrayDeque(two)

        val winner = playGame(oneDeque, twoDeque)
        val deque = if (winner == 1) oneDeque else twoDeque
        return deque.score()
    }

    private fun playGame(one: ArrayDeque<Int>, two: ArrayDeque<Int>): Int {
        val playedGames = mutableSetOf<PlayedGame>()

        while (one.isNotEmpty() && two.isNotEmpty()) {
            if (!playedGames.add(PlayedGame(one.toList(), two.toList()))) return 1

            val a = one.removeFirst()
            val b = two.removeFirst()

            val winner = when {
                one.size >= a && two.size >= b -> playGame(
                    ArrayDeque(one.take(a)),
                    ArrayDeque(two.take(b))
                )
                a > b -> 1
                else -> 2
            }

            if (winner == 1) {
                one.addLast(a)
                one.addLast(b)
            } else {
                two.addLast(b)
                two.addLast(a)
            }

        }

        return if (one.isEmpty()) 2 else 1
    }
}