package day_07

import (
	"strconv"
	"strings"
)

type Equation struct {
	Result    int
	Variables []int
}

// task:https://adventofcode.com/2024/day/7
func SolveBasic(input string) int {
	equations := loadEquations(input)

	sum := 0
	for _, equation := range equations {
		if Solvable(equation) {
			sum += equation.Result
		}
	}
	return sum
}

func Solvable(equation Equation) bool {
	for i := 0; i < 1<<(len(equation.Variables)-1); i++ {
		if solvable(equation, i) {
			return true
		}
	}
	return false
}

func solvable(equation Equation, options int) bool {
	sum := equation.Variables[0]
	for i := 0; i < len(equation.Variables)-1; i++ {
		if sum > equation.Result {
			return false
		}
		if options&(1<<i) != 0 {
			sum *= equation.Variables[i+1]
		} else {
			sum += equation.Variables[i+1]
		}
	}
	return sum == equation.Result
}

// task:https://adventofcode.com/2024/day/7#part2
func SolveComplex(input string) int {
	return 0
}

func loadEquations(input string) (equations []Equation) {
	lines := strings.Split(input, "\n")

	for _, line := range lines {
		equations = append(equations, loadEquation(line))
	}
	return
}

func loadEquation(line string) Equation {
	substrings := strings.Split(line, ": ")
	equation := Equation{
		Result: must(strconv.Atoi(substrings[0])),
	}
	for _, param := range strings.Split(substrings[1], " ") {
		equation.Variables = append(equation.Variables, must(strconv.Atoi(param)))
	}
	return equation
}

func must(val int, err error) int {
	if err != nil {
		panic(err)
	}
	return val
}