package two

import (
	"bytes"
)

const empty = -1

func Solve(buf []byte) (int, error) {
	r := bytes.NewReader(buf)
	expandedRaw, err := parseLines(r)
	if err != nil {
		return 0, err
	}

	disk := newDisk(expandedRaw)
	disk.defragment()
	disk.write()

	var sum int
	for i, n := range disk.data {
		if n == empty {
			continue
		}

		sum += i * n
	}

	return sum, nil
}