package six

import (
	"bufio"
	"os"
	"strconv"
	"strings"
)

type lanternfish struct {
	fish       map[int]int
	population int
}

func (l *lanternfish) load(filename string) error {
	file, err := os.Open(filename)
	if err != nil {
		return err
	}
	defer file.Close()
	scanner := bufio.NewScanner(file)
	l.fish = map[int]int{}
	for scanner.Scan() {
		fishes := strings.Split(scanner.Text(), ",")
		for _, fishy := range fishes {
			f, err := strconv.Atoi(fishy)
			if err != nil {
				return err
			}

			l.fish[f]++
		}
	}

	for _, count := range l.fish {
		l.population += count
	}

	return nil
}

func (l *lanternfish) simulate(days int) {
	for i := 0; i < days; i++ {
		// How many fish spawn today
		newFish := l.fish[0]

		// Advance spawn counts
		for j := 0; j < 8; j++ {
			l.fish[j] = l.fish[j+1]
		}

		// Reset spawning fish to 6 days
		l.fish[6] += newFish

		// Add new fish to day 8
		l.fish[8] = newFish

		population := 0
		for _, count := range l.fish {
			population += count
		}

		l.population = population
	}
}