package internal

import (
	"fmt"
	"hash/fnv"
	"os"
	"path/filepath"
	"sort"
	"strconv"
	"strings"
)

func Hash(key []byte) uint64 {
	h := fnv.New64a()
	h.Write(key)
	return h.Sum64()
}

func Exists(path string) bool {
	_, err := os.Stat(path)
	return err == nil
}

func DirSize(path string) (int64, 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
	})
	return size, err
}

func GetDatafiles(path string) ([]string, error) {
	fns, err := filepath.Glob(fmt.Sprintf("%s/*.data", path))
	if err != nil {
		return nil, err
	}
	sort.Strings(fns)
	return fns, nil
}

func ParseIds(fns []string) ([]int, error) {
	var ids []int
	for _, fn := range fns {
		fn = filepath.Base(fn)
		ext := filepath.Ext(fn)
		if ext != ".data" {
			continue
		}
		id, err := strconv.ParseInt(strings.TrimSuffix(fn, ext), 10, 32)
		if err != nil {
			return nil, err
		}
		ids = append(ids, int(id))
	}
	sort.Ints(ids)
	return ids, nil
}