package be.vandewalleh.aoc.days

import be.vandewalleh.aoc.utils.input.Day
import be.vandewalleh.aoc.utils.input.Lines
import org.eclipse.collections.api.bag.Bag
import org.eclipse.collections.api.bag.MutableBag
import org.eclipse.collections.api.factory.Bags

@Day(24)
class Day24(@Lines val input: List<String>) {

    private data class HexPoint(val x: Int, val y: Int, val z: Int) {
        fun translate(other: HexPoint) = HexPoint(this.x + other.x, this.y + other.y, this.z + other.z)
    }

    private enum class Direction(vararg coordinates: Int) {
        E(1, -1, 0),
        SE(0, -1, 1),
        SW(-1, 0, 1),
        W(-1, 1, 0),
        NW(0, 1, -1),
        NE(1, 0, -1);

        val coordinates = HexPoint(coordinates[0], coordinates[1], coordinates[2])
    }

    private fun parseTile(line: String) = "e|se|sw|w|nw|ne".toRegex()
        .findAll(line)
        .flatMap { it.groupValues }
        .map { Direction.valueOf(it.toUpperCase()) }
        .toList()

    private val tiles = input.map { parseTile(it) }.map {
        it.map { it.coordinates }.reduce { acc, ints -> acc.translate(ints) }
    }

    fun part1() = Bags.immutable.ofAll(tiles).selectBlacks().size()

    private fun Bag<HexPoint>.selectBlacks() = selectByOccurrences { it % 2 == 1 }

    private fun HexPoint.adjacents() = Direction.values().map { this.translate(it.coordinates) }

    // black -> odd
    // white -> even || not in bag -> !in black
    private fun day(bag: MutableBag<HexPoint>) {
        val blacks = bag.selectBlacks().toSet()

        val all = (bag + bag.flatMap { it.adjacents() }).toSet()

        for (tile in all) {
            val adjacents = tile.adjacents()
            val adjacentBlacks = adjacents.count { it in blacks }
            val isBlack = tile in blacks

            if (isBlack && (adjacentBlacks == 0 || adjacentBlacks > 2)) bag.setOccurrences(tile, 2)
            else if (!isBlack && adjacentBlacks == 2) bag.setOccurrences(tile, 1)
        }
    }

    fun part2(): Int {
        val bag = Bags.mutable.ofAll(tiles)
        repeat(100) { day(bag) }
        return bag.selectBlacks().size()
    }
}