package day2

import java.io.File

object Day2 {

    fun sumOfCompatibleGames(hand: Hand) = readGames()
        .filter { it.isCompatibleWith(hand) }
        .map(Game::id)
        .sum()

    private fun readGames(): List<Game> =
        File("src/main/resources/day2/input.txt")
            .readLines()
            .map(Game.Companion::parse)

}

data class Game(val id: Int, val hands: List<Hand>) {
    fun isCompatibleWith(hand: Hand) =
        hand.fitsIn(
            hands.fold(Hand(0, 0, 0)) { currentMax: Hand, next: Hand ->
                Hand(
                    maxOf(currentMax.red, next.red),
                    maxOf(currentMax.green, next.green),
                    maxOf(currentMax.blue, next.blue)
                )
            })

    companion object {

        /**
         * Example string: "Game 1: 3 blue, 4 red; 1 red, 2 green, 6 blue; 2 green"
         */
        fun parse(string: String) = string
            .split(':')
            .let {
                Game(
                    id = NUMBER_REGEX.find(it[0])!!.value.toInt(),
                    hands = it[1].split(';').map { Hand.parse(it) })
            }


        private val NUMBER_REGEX = Regex("\\d")
    }
}

data class Hand(val red: Int, val green: Int, val blue: Int) {
    fun fitsIn(other: Hand) = red >= other.red && green >= other.green && blue >= other.blue

    companion object {

        /**
         * Example string: "3 blue, 4 red"
         */
        fun parse(string: String): Hand =
            Hand(
                RED_REGEX.find(string)?.groupValues?.get(1)?.toInt() ?: 0,
                GREEN_REGEX.find(string)?.groupValues?.get(1)?.toInt() ?: 0,
                BLUE_REGEX.find(string)?.groupValues?.get(1)?.toInt() ?: 0
            )

        private val RED_REGEX = Regex("""(\d+)\s+red""")
        private val GREEN_REGEX = Regex("""(\d+)\s+green""")
        private val BLUE_REGEX = Regex("""(\d+)\s+blue""")
    }
}