AOC2022/day22/day22.go

package main

import (
	"AOC2022/helper"
	"fmt"
	"strconv"
	"strings"
)

func main() {
	//args := os.Args[1:]
	lines := helper.ReadTextFile("day22/input")
	field := [][]rune{}
	for _, line := range lines {
		if line == "" {
			break
		}
		field = append(field, []rune(line))
	}
	commandsLine := lines[len(lines)-1]
	commandsLine = strings.ReplaceAll(commandsLine, "R", "R,")
	commandsLine = strings.ReplaceAll(commandsLine, "L", "L,")
	commands := strings.Split(commandsLine, ",")
	currentPosition := [3]int{0, 0, 0}
	for i, c := range field[0] {
		if c == '.' {
			currentPosition[1] = i
			break
		}
	}
	fmt.Println(currentPosition)

	for _, command := range commands {
		fmt.Println(command)
		currentPosition = runCommand(field, command, currentPosition)
		fmt.Println(currentPosition)
	}
	fmt.Println(currentPosition)
	fmt.Println(1000*(currentPosition[0]+1) + 4*(currentPosition[1]+1) + currentPosition[2])

}

func runCommand(field [][]rune, command string, currentPosition [3]int) [3]int {
	rotation := command[len(command)-1]
	if rotation < 57 {
		rotation = 0
	} else {
		command = command[:len(command)-1]
	}
	distance := helper.RemoveError(strconv.Atoi(command))
	currentPosition = move(field, currentPosition, distance)
	if rotation == 'R' {
		newDirection := currentPosition[2] + 1
		if newDirection > 3 {
			newDirection = 0
		}
		currentPosition[2] = newDirection
	}
	if rotation == 'L' {
		newDirection := currentPosition[2] - 1
		if newDirection < 0 {
			newDirection = 3
		}
		currentPosition[2] = newDirection
	}

	return currentPosition
}

func getDirection(currentPosition [3]int) [2]int {
	directions := [][2]int{{0, 1}, {1, 0}, {0, -1}, {-1, 0}}
	return directions[currentPosition[2]]
}

func move(field [][]rune, currentPosition [3]int, distance int) [3]int {
	direction := getDirection(currentPosition)
	for i := 0; i < distance; i++ {
		tmpPosition := [2]int{currentPosition[0], currentPosition[1]}
		tmpPosition[0] += direction[0]
		tmpPosition[1] += direction[1]
		check := checkPosition(field, tmpPosition)
		if check == 2 {
			break
		}
		if check == 1 {
			currentPosition = loop(field, currentPosition)
		}
		if check == 0 {
			currentPosition[0] = tmpPosition[0]
			currentPosition[1] = tmpPosition[1]
		}
	}
	return currentPosition
}

//2  - Collision
//1  - Out Of Bounds
//0  - Fine
func checkPosition(field [][]rune, position [2]int) int {
	if position[0] >= len(field) || position[0] < 0 {
		return 1
	}
	if position[1] >= len(field[position[0]]) || position[1] < 0 {
		return 1
	}
	switch field[position[0]][position[1]] {
	case ' ':
		return 1
	case '.':
		return 0
	case '#':
		return 2
	}
	return -1
}

func loop(field [][]rune, currentPosition [3]int) [3]int {
	direction := getDirection(currentPosition)
	newStartPosition := [2]int{0, 0}
	if direction[0] == 0 {
		newStartPosition[0] = currentPosition[0]
	}
	if direction[0] < 0 {
		newStartPosition[0] = len(field) - 1
	}
	if direction[1] == 0 {
		newStartPosition[1] = currentPosition[1]
	}
	if direction[1] < 0 {
		newStartPosition[1] = len(field[newStartPosition[0]]) - 1
	}
	for checkPosition(field, newStartPosition) == 1 {
		newStartPosition[0] += direction[0]
		newStartPosition[1] += direction[1]
	}
	if checkPosition(field, newStartPosition) == 0 {
		currentPosition[0] = newStartPosition[0]
		currentPosition[1] = newStartPosition[1]
	}
	return currentPosition
}