package day17

import (
	"crypto/md5"
	"fmt"
	"math"
	"tools"
)

func getMD5Sum(s string) string {
	return fmt.Sprintf("%x", md5.Sum([]byte(s)))
}

type DirDelta struct {
	x int
	y int
}

var dirDeltas = []DirDelta{{0, -1}, {0, 1}, {-1, 0}, {1, 0}}
var dirs = []string{"U", "D", "L", "R"}
var pathLen = math.MaxInt32
var foundPath = ""

func findPath(passcode, path string, x, y int, findLongest bool) {
	doors := getMD5Sum(passcode + path)[:4]
	if !findLongest && len(path) >= pathLen {
		return
	}
	if x == 3 && y == 3 {
		if findLongest {
			if len(path) > pathLen {
				foundPath = path
				pathLen = len(path)
			}
		} else {
			if len(path) < pathLen {
				foundPath = path
				pathLen = len(path)
			}
		}
		return
	}

	for i, c := range doors {
		if x+dirDeltas[i].x < 0 || x+dirDeltas[i].x > 3 || y+dirDeltas[i].y < 0 || y+dirDeltas[i].y > 3 {
			// border case
			continue
		}

		if c > 97 { // door open
			findPath(passcode, path+dirs[i], x+dirDeltas[i].x, y+dirDeltas[i].y, findLongest)
		}
	}
}

func Part1(puzzle tools.AoCPuzzle) interface{} {
	for _, passcode := range puzzle.GetInputArray() {
		pathLen = math.MaxInt32
		findPath(passcode, "", 0, 0, false)
		// fmt.Println("Passcode:", passcode, "Path:", foundPath)
	}

	return foundPath
}

func Part2(puzzle tools.AoCPuzzle) interface{} {
	for _, passcode := range puzzle.GetInputArray() {
		pathLen = 0
		findPath(passcode, "", 0, 0, true)
		// fmt.Println("Passcode:", passcode, "Len:", len(foundPath), "Path:", foundPath)
	}

	return len(foundPath)
}