Untitled

package main

import (
	"bufio"
	"fmt"
	"math"
	"os"
	"strconv"
	"strings"
	"unicode"
)

type dataMap = map[string]*[]string

func main() {
	f, err := os.Open("./input.txt")
	if err != nil {
		panic(err)
	}
	defer f.Close()
	s := bufio.NewScanner(f)

	crates := &dataMap{}

	for s.Scan() {
		line := s.Text()

		splitLine := strings.Split(line, " ")
		if splitLine[0] == "move" {
			crates = parseInstruction(splitLine, crates)
		} else {
			crates = parseLayout(line, crates)
		}
	}

	fmt.Println(crates)

	final := [10]string{}
	for k, v := range *crates {
		idx, _ := strconv.Atoi(k)
		final[idx] = (*v)[len((*v))-1]
	}

	fmt.Println(final)

}

func prepend(arr *[]string, item string) (ret []string) {
	return append([]string{item}, *arr...)
}

// creates a map keyed by id with letter array values
func parseLayout(line string, crates *dataMap) *dataMap {
	if line != "" {
		for i, l := range line {
			if unicode.IsLetter(l) {
				crateId := strconv.Itoa(int(math.Floor(float64(i)/4) + 1))
				targetContainer := (*crates)[crateId]
				*targetContainer = prepend((targetContainer), string(l))
			}
		}
	}
	return crates
}

func parseInstruction(line []string, crates *dataMap) *dataMap {
	amount, _ := strconv.Atoi(line[1])
	origin := (*crates)[line[3]]
	destination := (*crates)[line[5]]

	for i := 0; i < amount; i++ {
		moveCrate(origin, destination)
	}

	return crates
}

func moveCrate(origin *[]string, destination *[]string) {
	lastIdx := len(*origin) - 1
	last := (*origin)[lastIdx]
	*origin = (*origin)[:lastIdx]
	*destination = append(*destination, last)

}

//         [Q] [B]         [H]
//     [F] [W] [D] [Q]     [S]
//     [D] [C] [N] [S] [G] [F]
//     [R] [D] [L] [C] [N] [Q]     [R]
// [V] [W] [L] [M] [P] [S] [M]     [M]
// [J] [B] [F] [P] [B] [B] [P] [F] [F]
// [B] [V] [G] [J] [N] [D] [B] [L] [V]
// [D] [P] [R] [W] [H] [R] [Z] [W] [S]
//  1   2   3   4   5   6   7   8   9

// move 1 from 4 to 1
// move 2 from 4 to 8
// move 5 from 9 to 6
// move 1 from 1 to 3
// move 5 from 8 to 3
// move 1 from 1 to 5
// move 4 from 3 to 6
// move 14 from 6 to 2