package day6

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

func Run() int {
	input := ReadInput("day6/example")
	result := 1
	for _, race := range input {
		result *= race.countWinningMoves()
	}
	log.Printf("input %+v\n", input)
	return result
}

type Race struct {
	Time, Target int
}

func (r Race) countWinningMoves() int {
	// oh and it's simmetrical
	leftPad := 0
	rightPad := 0
	for i := 0; i < (r.Time / 2 + 1); i++ {
		if i * (r.Time - i) > r.Target {
			leftPad = i
			break
		}
	}
	for i := 0; i < (r.Time / 2 + 1); i++ {
		time := r.Time - i
		if time * (r.Time - time) > r.Target {
			rightPad = i
			break
		}
	}

	result := r.Time + 1 - leftPad - rightPad
	log.Printf("for race %+v got left %d and right %d for total wind %d\n", r, leftPad, rightPad, result)
	return result
}

func ReadInput(filename string) []Race {
	result := make([]Race, 0)

	bytes, err := os.ReadFile(filename)
	if err != nil {
		panic(fmt.Sprintln("problem readin input : ", filename))
	}
	text := strings.Split( string(bytes), "\n")
	times := strings.Fields(text[0])
	distances := strings.Fields(text[1])

	for i := 1; i < len(times); i++ {
		time, err1 := strconv.Atoi(times[i])
		target, err2 := strconv.Atoi(distances[i])
		if err1 != nil || err2 != nil {
			panic(fmt.Sprintf("error reading race %d from %s %s\n", i, times[i], distances[i]))
		}
		race := Race{
			Time: time,
			Target: target,
		}
		result = append(result, race)
	}

	return result
}



// my guess is that i can search from start and end into middle and stop when i find solution
// from the way i think derivation of x*y works
// but first - read in the input. with strings.Fields should be easy