package day16

import (
	"tools"
)

func expandState(state string) string {
	b := []rune(state)
	for i, j := 0, len(b)-1; i <= j; i, j = i+1, j-1 {
		x := b[j]
		if b[i] == 48 {
			b[j] = 49
		} else {
			b[j] = 48
		}
		if x == 48 {
			b[i] = 49
		} else {
			b[i] = 48
		}
	}

	return state + "0" + string(b)
}

func getCheckSum(state string) string {
	checksum := []byte(state)
	for len(checksum)%2 == 0 {
		var newsum []byte
		bytes := checksum
		for i := 0; i < len(bytes); i += 2 {
			newsum = append(newsum, 49-(bytes[i]+bytes[i+1])%2)
		}
		checksum = newsum
	}

	return string(checksum)
}

func Part1(puzzle tools.AoCPuzzle) interface{} {
	state := puzzle.GetInputArray()[0]

	for len(state) < 272 {
		state = expandState(state)
	}

	return getCheckSum(state[:272])
}

func Part2(puzzle tools.AoCPuzzle) interface{} {
	state := puzzle.GetInputArray()[0]

	for len(state) < 35651584 {
		state = expandState(state)
	}

	return getCheckSum(state[:35651584])
}