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package neembuu.uploader.utils;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

/**
 *
 * @author Shashank
 */
public class HashUtil {
    public static String hashFile(File file, String algorithm) {
        try (FileInputStream inputStream = new FileInputStream(file)) {
            MessageDigest digest = MessageDigest.getInstance(algorithm);

            byte[] bytesBuffer = new byte[1024];
            int bytesRead = -1;

            while ((bytesRead = inputStream.read(bytesBuffer)) != -1) {
                digest.update(bytesBuffer, 0, bytesRead);
            }

            byte[] hashedBytes = digest.digest();

            return convertByteArrayToHexString(hashedBytes);
        } catch (NoSuchAlgorithmException | IOException ex) {
            throw new IllegalStateException("Could not generate hash from file", ex);
        }
    }

    private static String convertByteArrayToHexString(byte[] arrayBytes) {
        StringBuffer stringBuffer = new StringBuffer();
        for (int i = 0; i < arrayBytes.length; i++) {
            stringBuffer.append(Integer.toString((arrayBytes[i] & 0xff) + 0x100, 16)
                    .substring(1));
        }
        return stringBuffer.toString();
    }
}