package day09

import (
	"math"
	"strconv"
	"strings"
	"tools"
)

func getDistanceMap(input []string) ([]string, map[string]map[string]int) {
	distances := make(map[string]map[string]int)
	var retCities []string

	for _, line := range input {
		distDescr := strings.Split(line, " = ")
		cities := strings.Split(distDescr[0], " to ")
		distance, _ := strconv.Atoi(distDescr[1])

		if _, ok := distances[cities[0]]; !ok {
			distances[cities[0]] = make(map[string]int)
			retCities = append(retCities, cities[0])
		}
		distances[cities[0]][cities[1]] = distance
		if _, ok := distances[cities[1]]; !ok {
			distances[cities[1]] = make(map[string]int)
			retCities = append(retCities, cities[1])
		}
		distances[cities[1]][cities[0]] = distance
	}

	return retCities, distances
}

func cityPermutations(slice []string) (permutations [][]string) {
	if len(slice) == 1 {
		return [][]string{slice}
	} else if len(slice) == 2 {
		return [][]string{
			{
				slice[0],
				slice[1],
			},
			{
				slice[1],
				slice[0],
			},
		}
	} else {
		for i := range slice {
			newSlice := make([]string, i)
			copy(newSlice, slice[:i])
			newSlice = append(newSlice, slice[i+1:]...)
			subPermutations := cityPermutations(newSlice)
			for _, subPermutation := range subPermutations {
				permutations = append(permutations, append([]string{slice[i]}, subPermutation...))
			}
		}
		return permutations
	}
}

func getMinMaxDistances(permutations [][]string, distances map[string]map[string]int) (int, int) {
	minDistance := math.MaxInt32
	maxDistance := 0

	for _, v := range permutations {
		thisDistance := 0
		for i := 0; i < len(v)-1; i++ {
			thisDistance += distances[v[i]][v[i+1]]
		}
		if thisDistance < minDistance {
			minDistance = thisDistance
		}
		if thisDistance > maxDistance {
			maxDistance = thisDistance
		}
	}

	return minDistance, maxDistance
}

func Part1(puzzle tools.AoCPuzzle) interface{} {
	cities, distances := getDistanceMap(puzzle.GetInputArray())
	minDistance, _ := getMinMaxDistances(cityPermutations(cities), distances)

	return minDistance
}

func Part2(puzzle tools.AoCPuzzle) interface{} {
	cities, distances := getDistanceMap(puzzle.GetInputArray())
	_, maxDistance := getMinMaxDistances(cityPermutations(cities), distances)

	return maxDistance
}