package org.simantics.fastlz;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

/**
 * @author Tuukka Lehtonen
 */
public final class ChecksumUtil {

    public static byte[] computeSum(byte[] in) {
        if (in == null)
            throw new IllegalArgumentException("Input cannot be null!");
        try {
            MessageDigest md = MessageDigest.getInstance("MD5");
            md.update(in, 0, in.length);
            return md.digest();
        } catch (NoSuchAlgorithmException e) {
            throw new Error("MD5 digest must be supported by JVM");
        }
    }

    public static byte[] computeSum(InputStream in) throws IOException {
        if (in == null)
            throw new IllegalArgumentException("Input cannot be null!");

        MessageDigest md;
        try {
            md = MessageDigest.getInstance("MD5");
        } catch (NoSuchAlgorithmException e) {
            throw new Error("MD5 digest must be supported by JVM");
        }
        byte[] data = new byte[64 * 1024];

        while (true) {
            int read = in.read(data);
            if (read == -1) {
                return md.digest();
            }
            md.update(data, 0, read);
        }
    }

    public static byte[] computeSum(File f) throws IOException {
        InputStream in = null;
        try {
            in = new FileInputStream(f);
            return computeSum(in);
        } finally {
            if (in != null)
                in.close();
        }
    }

    public static byte[] computeSum(URL url) throws IOException {
        InputStream in = null;
        try {
            in = url.openStream();
            return computeSum(in);
        } finally {
            if (in != null)
                in.close();
        }
    }

}