package utils

/**
 * SHA-256 Hashing Class
 *
 * @author 			Jérémi N <contact@enmove.eu>
 * @version 		1.0
 */
import (
	"bufio"
	"crypto/sha256"
	"errors"
	"fmt"
	"io"
	"os"
	"strings"
)

// HashStream Make a fingerprint of a stream.
func HashStream(in *bufio.Reader) (string, error) {
	sha := sha256.New()
	if _, err := io.Copy(sha, in); err != nil {
		return "", errors.New("unable to copy data into hashing system")
	}
	return fmt.Sprintf("%x", sha.Sum(nil)), nil
}

// HashFile Make a fingerprint of a file content.
func HashFile(filePath string) (string, error) {
	file, err := os.Open(filePath)
	if err != nil {
		return "", err
	}
	defer file.Close()
	hash, err := HashStream(bufio.NewReader(file))
	if err != nil {
		return "", err
	}
	return hash, nil
}

// HashFileCompare Make a fingerprint of a file and compare with the renseigned fingerprint.
func HashFileCompare(filePath string, fingerprint string) (bool, error) {
	fileFingerprint, err := HashFile(filePath)
	if err != nil {
		return false, err
	}

	if strings.Compare(fileFingerprint, fingerprint) == 0 {
		return true, nil
	}
	return false, nil
}