/*
 * ome.io.nio.itests.Helper
 *
 *   Copyright 2006 University of Dundee. All rights reserved.
 *   Use is subject to license terms supplied in LICENSE.txt
 */
package ome.io.nio.itests;

import java.nio.ByteBuffer;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

/**
 * @author callan
 * 
 */
public class Helper {
    private static MessageDigest newSha1MessageDigest() {
        MessageDigest md;

        try {
            md = MessageDigest.getInstance("SHA-1");
        } catch (NoSuchAlgorithmException e) {
            throw new RuntimeException(
                    "Required SHA-1 message digest algorithm unavailable.");
        }

        md.reset();
        return md;
    }

    public static byte[] calculateMessageDigest(ByteBuffer buffer) {
        MessageDigest md = newSha1MessageDigest();
        md.update(buffer);
        return md.digest();
    }

    public static byte[] calculateMessageDigest(byte[] buffer) {
        MessageDigest md = newSha1MessageDigest();
        md.update(buffer);
        return md.digest();
    }

    /**
     * Convenience method to convert a byte to a hex string.
     * 
     * @param data
     *            the byte to convert
     * @return String the converted byte
     */
    @Deprecated
    public static String byteToHex(byte data) {
        StringBuffer buf = new StringBuffer();
        buf.append(toHexChar(data >>> 4 & 0x0F));
        buf.append(toHexChar(data & 0x0F));
        return buf.toString();
    }

    /**
     * Convenience method to convert an int to a hex char.
     * 
     * @param i
     *            the int to convert
     * @return char the converted char
     */
    @Deprecated
    public static char toHexChar(int i) {
        if (0 <= i && i <= 9) {
            return (char) ('0' + i);
        } else {
            return (char) ('a' + i - 10);
        }
    }

    /**
     * Convenience method to convert a byte array to a hex string.
     * 
     * @param data
     *            the byte[] to convert
     * @return String the converted byte[]
     */
    @Deprecated
    public static String bytesToHex(byte[] data) {
        StringBuffer buf = new StringBuffer();
        for (int i = 0; i < data.length; i++) {
            buf.append(byteToHex(data[i]));
        }
        return buf.toString();
    }
}