package be.vandewalleh.aoc.days

import be.vandewalleh.aoc.utils.input.Day
import be.vandewalleh.aoc.utils.input.Groups
import java.util.*

@Day(19)
class Day19(@Groups val input: List<List<String>>) {
    private val rules = input[0]
    private val messages = input[1]

    sealed class Rule {
        data class CharRule(val value: Char) : Rule()
        data class OrRule(val a: List<Int>, val b: List<Int>?) : Rule() {
            val all get() = listOfNotNull(a, b)
        }
    }

    private fun parseRules(): Map<Int, Rule> {
        val parsedRules = mutableMapOf<Int, Rule>()
        rules.forEach {
            val parts = it.split(":", limit = 2)
            val index = parts[0].toInt()
            val rule = if ("\"" !in parts[1]) {
                val p = parts[1].split('|', limit = 2).map { it.trim().split(" ").mapTo(ArrayList(2)) { it.toInt() } }
                Rule.OrRule(p[0], if (p.size == 2) p[1] else null)
            } else {
                Rule.CharRule(parts[1].trim().replace("\"", "")[0])
            }
            parsedRules[index] = rule
        }
        return parsedRules
    }

    private fun matches(input: String, queue: ArrayDeque<Int>, rules: Map<Int, Rule>): Boolean =
        if (queue.isEmpty()) input.isEmpty()
        else if (input.isEmpty()) queue.isEmpty()
        else when (val rule = rules[queue.pop()]!!) {
            is Rule.CharRule -> input[0] == rule.value && matches(input.drop(1), queue, rules)
            is Rule.OrRule -> rule.all.any { matches(input, queue.clone().apply { it.asReversed().forEach { addFirst(it) } }, rules) }
        }

    fun part1(): Int {
        val rules = parseRules()
        return messages.count { matches(it, ArrayDeque<Int>().apply { add(0) }, rules) }
    }

    fun part2(): Int {
        val rules = parseRules().toMutableMap()
        rules[8] = Rule.OrRule(listOf(42), listOf(42, 8))
        rules[11] = Rule.OrRule(listOf(42, 31), listOf(42, 11, 31))
        return messages.count { matches(it, ArrayDeque<Int>().apply { add(0) }, rules) }
    }

}