package org.jacorb.poa.util;

import java.util.Arrays;
import java.util.Random;


/*
 *        JacORB - a free Java ORB
 *
 *   Copyright (C) 1997-2014 Gerald Brose / The JacORB Team.
 *
 *   This library is free software; you can redistribute it and/or
 *   modify it under the terms of the GNU Library General Public
 *   License as published by the Free Software Foundation; either
 *   version 2 of the License, or (at your option) any later version.
 *
 *   This library is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *   Library General Public License for more details.
 *
 *   You should have received a copy of the GNU Library General Public
 *   License along with this library; if not, write to the Free
 *   Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

/**
 * This class collects some oid related basic routines.
 *
 * @author Reimo Tiedemann, FU Berlin
 * @version 1.05, 21/01/00, RT
 */

public final class IdUtil
{
    private static final Random rnd = new Random (9999);

    public static byte[] concat(byte[] first, byte[] second)
    {
	byte[] result = new byte[first.length+second.length];
	System.arraycopy(first, 0, result, 0, first.length);
	System.arraycopy(second, 0, result, first.length, second.length);
	return result;
    }

    /**
     * creates an id as a concatenation of the current time in msec
     * and 4 random bytes
     */
    public static byte[] createId()
    {
        byte[] time = toId (System.nanoTime());
        byte[] random = toId (rnd.nextLong());
        return concat(time, random);
    }

    public static boolean equals(byte[] first, byte[] second)
    {
        return Arrays.equals(first, second);
    }

    /**
     * compares first len bytes of two byte arrays
     */

    public static boolean equals(byte[] first, byte[] second, int len)
    {
        if (first == second)
        {
            return true;
        }

        if (first.length < len || second.length < len)
        {
            return false;
        }

	for (int i=0; i<len; i++)
	{
            if (first[i] != second[i])
            {
                return false;
            }
	}
	return true;
    }

    /**
     * extracts len bytes from id, the first byte to be copied is at index offset
     */
    public static byte[] extract(byte[] id, int offset, int len)
    {
	byte[] result = new byte[len];
	System.arraycopy(id, offset, result, 0, len);
	return result;
    }

    /**
     * converts the number l into a byte array
     */
    public static byte[] toId(long l)
    {
	String str = Long.toOctalString(l);

        if (str.length() % 2 != 0)
        {
            str = "0" + str;
        }

        byte[] result = new byte[str.length()/2];
 	StringBuffer number = new StringBuffer("xx");

        for (int i=0; i<result.length; i++)
        {
	    number.setCharAt(0, str.charAt(i*2));
	    number.setCharAt(1, str.charAt(i*2+1));
	    result[i] = Integer.valueOf(number.toString()).byteValue();

            if (result[i] == org.jacorb.poa.POAConstants.OBJECT_KEY_SEP_BYTE)
            {
		result[i] = (byte) 48;     // char 0 , hex 30
	    }
            else if (result[i] == org.jacorb.poa.POAConstants.MASK_BYTE)
            {
		result[i] = (byte) 19;     // char !!, hex 13
	    }
	}
	return result;
    }
}