/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 * 
 *   http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.    
 */
package org.apache.tuscany.sca.databinding.xstream;

import java.io.IOException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;

/**
 * Utility methods.
 *
 * @version $Rev$ $Date$
 */
public class Utils {
    public static String toBase64(byte[] array) {
        String code = null;
        code = new sun.misc.BASE64Encoder().encode(array);
        return code;
    }

    public static byte[] fromBase64(String bytecode) {
        byte[] dec = null;
        try {
            dec = new sun.misc.BASE64Decoder().decodeBuffer(bytecode);
        } catch (IOException e) {
            e.printStackTrace();
        }
        return dec;
    }

    public static String uniqueID() {
        try {
            //Initialize SecureRandom
            //This is a lengthy operation, to be done only upon
            //initialization of the application
            SecureRandom prng = SecureRandom.getInstance("SHA1PRNG");

            //generate a random number
            String randomNum = Integer.toString(prng.nextInt());

            //get its digest
            MessageDigest sha = MessageDigest.getInstance("SHA-1");
            byte[] result = sha.digest(randomNum.getBytes());
            return hexEncode(result);
        } catch (NoSuchAlgorithmException ex) {
            ex.printStackTrace();
        }
        return null;
    }

    private static String hexEncode(byte[] aInput) {
        StringBuffer result = new StringBuffer();
        char[] digits = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'};
        for (int idx = 0; idx < aInput.length; ++idx) {
            byte b = aInput[idx];
            result.append(digits[(b & 0xf0) >> 4]);
            result.append(digits[b & 0x0f]);
        }
        return result.toString();
    }

}