package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
	"time"
)

const FILE_PATH = "./input.txt"

//const FILE_PATH = "./sample.txt"

func LoadInput(filename string) ([]string, error) {
	file, err := os.Open(filename)
	if err != nil {
		return nil, err
	}
	defer file.Close()

	var lines []string
	scanner := bufio.NewScanner(file)
	for scanner.Scan() {
		lines = append(lines, scanner.Text())
	}

	if err := scanner.Err(); err != nil {
		return nil, err
	}

	return lines, nil
}

type Vector2 struct {
	x int
	y int
}

type Puzzle struct {
	buttonA Vector2
	buttonB Vector2
	price   Vector2
}

type structuredInput = []Puzzle

func TransformInput(lines []string) structuredInput {
	var result = make([]Puzzle, 0)
	var numb int
	var buttonA Vector2
	var buttonB Vector2
	var prize Vector2
	var j int
	for i := 0; i < len(lines); i += 4 {
		buttonA = Vector2{}
		numb, _ = strconv.Atoi(lines[i][len("Button A: X+") : len("Button A: X+")+2])
		buttonA.x = numb
		numb, _ = strconv.Atoi(lines[i][len("Button A: X+")+5 : len("Button A: X+")+8])
		buttonA.y = numb

		buttonB = Vector2{}
		numb, _ = strconv.Atoi(lines[i+1][len("Button A: X+") : len("Button A: X+")+2])
		buttonB.x = numb
		numb, _ = strconv.Atoi(lines[i+1][len("Button A: X+")+5 : len("Button A: X+")+8])
		buttonB.y = numb

		prize = Vector2{}
		j = 0
		for ; j < len(lines[i+2]); j++ {
			if lines[i+2][j] == ',' {
				break
			}
		}
		numb, _ = strconv.Atoi(lines[i+2][len("Prize: X="):j])
		prize.x = numb
		numb, _ = strconv.Atoi(lines[i+2][j+4:])
		prize.y = numb

		result = append(result, Puzzle{buttonA, buttonB, prize})
	}

	return result
}

func calculatePuzzleSolution(puzzle Puzzle) int {
	var mf float64 = 0
	var m int
	var n int

	// This case would be possible if a and b are multiple of each other so either b or a must be 0 this is never the case
	if puzzle.buttonB.x*puzzle.buttonA.y == puzzle.buttonA.x*puzzle.buttonB.y || puzzle.buttonB.x*puzzle.buttonB.y == 0 {
		return 0
	}

	mf = float64(puzzle.buttonB.x*puzzle.price.y-puzzle.price.x*puzzle.buttonB.y) / float64(puzzle.buttonB.x*puzzle.buttonA.y-puzzle.buttonA.x*puzzle.buttonB.y)
	m = int(mf)

	if float64(m) != mf {
		return 0
	}

	n = (puzzle.price.x - puzzle.buttonA.x*m) / puzzle.buttonB.x

	return m*3 + n
}

func Part1(input structuredInput) int {
	var result = 0

	for _, puzzle := range input {
		result += calculatePuzzleSolution(puzzle)
	}

	return result
}

func Part2(input structuredInput) int {
	var result = 0

	for i := 0; i < len(input); i++ {
		input[i].price.x += 10000000000000
		input[i].price.y += 10000000000000
	}

	for _, puzzle := range input {
		result += calculatePuzzleSolution(puzzle)
	}

	return result
}

func main() {
	var start time.Time
	var elapsed time.Duration = 0
	input, err := LoadInput(FILE_PATH)
	if err != nil {
		fmt.Println("Error loading input:", err)
		return
	}

	structuredInput := TransformInput(input)
	fmt.Println("Structured Input:", structuredInput)

	start = time.Now()
	fmt.Println("Solution Part 1: ", Part1(structuredInput))
	elapsed = time.Since(start)
	fmt.Printf("Part 1 took %s\n", elapsed)

	start = time.Now()
	fmt.Println("Solution Part 2: ", Part2(structuredInput))
	elapsed = time.Since(start)
	fmt.Printf("Part 2 took %s\n", elapsed)
}