package day_03

import (
	"fmt"
	"regexp"
	"strings"
)

// task:https://adventofcode.com/2024/day/2
// short summary - find valid mul instructions in corrupted memory
// commands are valid if they are in the form "mul(" + %d "," + %d + ")"
func SolveBasic(input string) int {
	expr, err := regexp.Compile("mul\\(\\d*,\\d*\\)")
	if err != nil {
		panic(err)
	}
	instructions := expr.FindAllString(input, -1)
	sum := calculate(instructions)
	return sum
}

// task:https://adventofcode.com/2024/day/2#part2
// short summary - find valid mul instructions in corrupted memory
// commands are valid if they are in the form "mul(" + %d "," + %d + ")"
// everytime there is a don't() instruction in memory we ignore muls until we reach a do() command
func SolveComplex(input string) int {
	expr, err := regexp.Compile("mul\\(\\d*,\\d*\\)")
	if err != nil {
		panic(err)
	}
	instructionString := ""
	// we split string everytime actions get enabled
	doSubstrings := strings.Split(input, "do()")
	for _, s := range doSubstrings {
		// then we split on the first appearance of don't(),
		// making that the first substrings has valid instructions
		substrings := strings.Split(s, "don't()")
		instructionString += substrings[0]
	}
	instructions := expr.FindAllString(instructionString, -1)
	sum := calculate(instructions)
	return sum
}

func calculate(instructions []string) int {
	sum := 0
	for _, instr := range instructions {
		a := 0
		b := 0
		_, err := fmt.Sscanf(instr, "mul(%d,%d)", &a, &b)
		if err != nil {
			panic(err)
		}
		sum += a * b
	}
	return sum
}

// helper methods