/*

 * Copyright (c) 2013, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code 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 General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package sun.management.jdp;

import java.io.ByteArrayOutputStream;

import java.io.DataOutputStream;

import java.io.IOException;

/**

 * JdpPacketWriter responsible for writing a packet

 * <p>This class assembles a set of key/value pairs to valid JDP packet,

 * ready to be sent across a Net</p>

 */

public final class JdpPacketWriter {

    private final ByteArrayOutputStream baos;

    private final DataOutputStream pkt;

    /**

     * Create a JDP packet, add mandatory magic and version headers

     *

     * @throws IOException

     */

    public JdpPacketWriter()

            throws IOException {

        baos = new ByteArrayOutputStream();

        pkt = new DataOutputStream(baos);

        pkt.writeInt(JdpGenericPacket.getMagic());

        pkt.writeShort(JdpGenericPacket.getVersion());

    }

    /**

     * Put string entry to packet

     *

     * @param entry - string to put (utf-8 encoded)

     * @throws IOException

     */

    public void addEntry(String entry)

            throws IOException {

        /* DataOutputStream.writeUTF() do essentially

         *  the same as:

         *    pkt.writeShort(entry.getBytes("UTF-8").length);

         *    pkt.write(entry.getBytes("UTF-8"));

         */

        pkt.writeUTF(entry);

    }

    /**

     * Put key/value pair to packet

     *

     * @param key - key to put (utf-8 encoded)

     * @param val - value to put (utf-8 encoded)

     * @throws IOException

     */

    public void addEntry(String key, String val)

            throws IOException {

        /* Silently skip key if value is null.

         * We don't need to distinguish between key missing

         * and key has no value cases

         */

        if (val != null) {

            addEntry(key);

            addEntry(val);

        }

    }

    /**

     * Return assembled packet as a byte array

     *

     * @return packet bytes

     */

    public byte[] getPacketBytes() {

        return baos.toByteArray();

    }

}