package main

import (
	"log"
	"os"
	"strconv"
	"strings"
)

func main() {
	inputBytes, _ := os.ReadFile("input.txt")
	inputs := strings.Split(string(inputBytes), "\n")

	log.Println("Puzzle 1:", puzzle1(inputs))
	log.Println("Puzzle 2:", puzzle2(inputs))
}

func puzzle1(input []string) int {
	// "forward X" increases the horizontal position by X units.
	// "down X" increases the depth by X units.
	// "up X" decreases the depth by X units.
	horizontal := 0
	depth := 0
	for _, instruction := range input {
		instructionParts := strings.Split(instruction, " ")
		direction := instructionParts[0]
		distance, _ := strconv.Atoi(instructionParts[1])
		switch direction {
		case "forward":
			horizontal += distance
		case "down":
			depth += distance
		case "up":
			depth -= distance
		}
	}
	// Multiply horizontal position and depth together to get the final answer.
	return horizontal * depth
}

func puzzle2(input []string) int {
	// down X increases your aim by X units.
	// up X decreases your aim by X units.
	// forward X does two things:
	// - It increases your horizontal position by X units.
	// - It increases your depth by your aim multiplied by X.
	horizontal := 0
	depth := 0
	aim := 0
	for _, instruction := range input {
		instructionParts := strings.Split(instruction, " ")
		direction := instructionParts[0]
		distance, _ := strconv.Atoi(instructionParts[1])
		switch direction {
		case "down":
			aim += distance
		case "up":
			aim -= distance
		case "forward":
			horizontal += distance
			depth += aim * distance
		}
	}
	// Multiply horizontal position and depth together to get the final answer.
	return horizontal * depth
}