package fsutil

import (
	"os"
	"path/filepath"

	"golang.org/x/xerrors"
)

type SizeInfo struct {
	OnDisk int64
}

// FileSize returns bytes used by a file or directory on disk
func FileSize(path string) (SizeInfo, error) {
	var size int64
	err := filepath.Walk(path, func(_ string, info os.FileInfo, err error) error {
		if err != nil {
			return err
		}
		if !info.IsDir() {
			size += info.Size()
		}
		return err
	})
	if err != nil {
		if os.IsNotExist(err) {
			return SizeInfo{}, os.ErrNotExist
		}
		return SizeInfo{}, xerrors.Errorf("filepath.Walk err: %w", err)
	}

	return SizeInfo{size}, nil
}