/*
 * This file is part of jNAT-PMPlib.
 *
 * jNAT-PMPlib is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * jNAT-PMPlib 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with jNAT-PMPlib.  If not, see <http://www.gnu.org/licenses/>.
 */

package net.tomp2p.natpmp;

import java.net.Inet4Address;
import java.net.UnknownHostException;

/**
 * This class manages an External Address message. This class is thread-safe.
 * After instantiation, this class may be added to the message queue on the
 * {@link NatPmpDevice}.
 * 
 * @author flszen
 */
public class ExternalAddressRequestMessage extends Message {
    private byte[] payload = new byte[] { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };

    private Inet4Address externalAddress;

    /**
     * Constructs a new {@link ExternalAddressRequestMessage}.
     * 
     * @param listener
     *            The {@link MessageResponseInterface} that will respond to the
     *            message result.
     */
    public ExternalAddressRequestMessage(MessageResponseInterface listener) {
        super(MessageType.ExternalAddress, listener);
    }

    /**
     * Gets the NAT-PMP gateway's external address.
     * 
     * @return The external {@link Inet4Address} of the NAT-PMP gateway.
     * @throws NatPmpException
     *             Thrown when no response has been received or the response
     *             parsing ran into some trouble.
     */
    public Inet4Address getExternalAddress() throws NatPmpException {
        // Return the address.
        return externalAddress;
    }

    void parseResponse(byte[] response) throws NatPmpException {
        try {
            byte[] copy = new byte[4];
            System.arraycopy(response, 8, copy, 0, 4);
            externalAddress = (Inet4Address) Inet4Address.getByAddress(copy);
        } catch (UnknownHostException ex) {
            throw new NatPmpException("Unable to parse external address.", ex);
        }
    }

    byte[] getRequestPayload() {
        return (byte[]) payload.clone();
    }

    byte getOpcode() {
        return 0;
    }
}