package utils

import (
	"encoding/binary"
	"hash/fnv"
	"io"
	"mime/multipart"
	"os"
)

func FileHashFromUpload(file multipart.File) (string, error) {
	h := fnv.New64a()
	if _, err := io.Copy(h, file); err != nil {
		return "", err
	}

	return u64ToString(h.Sum64()), nil
}

func FileHash(path string) (string, error) {
	f, err := os.Open(path)
	if err != nil {
		return "", err
	}
	defer f.Close()

	h := fnv.New64a()
	if _, err := io.Copy(h, f); err != nil {
		return "", err
	}

	return u64ToString(h.Sum64()), nil
}

func u64ToString(x uint64) string {
	var b [8]byte
	binary.LittleEndian.PutUint64(b[:], x)
	return string(b[:])
}