package utility

import (
	"crypto/sha512"
	"encoding/hex"
	"io"
	"mime/multipart"
	"os"
)

func HashReader(r io.Reader) (string, error) {
	h := sha512.New()
	if _, err := io.Copy(h, r); err != nil {
		return "", err
	}

	// return the sha checksum in hex
	return hex.EncodeToString(h.Sum(nil)), nil
	// alternatively return in base64
	//return base64.StdEncoding.EncodeToString(h.Sum(nil)), nil
}

func HashUpload(fileHeader *multipart.FileHeader) (string, error) {
	stream, err := fileHeader.Open()
	if err != nil {
		return "", err
	}
	defer stream.Close()

	return HashReader(stream)
}

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

	return HashReader(file)
}