/**
 * $RCSfile$
 * $Revision:  $
 * $Date: $
 *
 * Copyright 2003-2006 Jive Software.
 *
 * All rights reserved. Licensed 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.jivesoftware.smackx.muc;

import org.jivesoftware.smack.PacketInterceptor;
import org.jivesoftware.smack.packet.Packet;
import org.jivesoftware.smack.packet.PacketExtension;
import org.jivesoftware.smack.packet.Presence;

/**
 * Packet interceptor that will intercept presence packets sent to the MUC
 * service to indicate that the user wants to be a deaf occupant. A user can
 * only indicate that he wants to be a deaf occupant while joining the room. It
 * is not possible to become deaf or stop being deaf after the user joined the
 * room.
 * <p>
 * 
 * Deaf occupants will not get messages broadcasted to all room occupants.
 * However, they will be able to get private messages, presences, IQ packets or
 * room history. To use this functionality you will need to send the message
 * {@link MultiUserChat#addPresenceInterceptor(org.jivesoftware.smack.PacketInterceptor)}
 * and pass this interceptor as the parameter.
 * <p>
 * 
 * Note that this is a custom extension to the MUC service so it may not work
 * with other servers than Wildfire.
 * 
 * @author Gaston Dombiak
 */
public class DeafOccupantInterceptor implements PacketInterceptor {

	private static class DeafExtension implements PacketExtension {

		@Override
		public String getElementName() {
			return "x";
		}

		@Override
		public String getNamespace() {
			return "http://jivesoftware.org/protocol/muc";
		}

		@Override
		public String toXML() {
			final StringBuilder buf = new StringBuilder();
			buf.append("<").append(getElementName()).append(" xmlns=\"")
					.append(getNamespace()).append("\">");
			buf.append("<deaf-occupant/>");
			buf.append("</").append(getElementName()).append(">");
			return buf.toString();
		}
	}

	@Override
	public void interceptPacket(Packet packet) {
		final Presence presence = (Presence) packet;
		// Check if user is joining a room
		if (Presence.Type.available == presence.getType()
				&& presence.getExtension("x", "http://jabber.org/protocol/muc") != null) {
			// Add extension that indicates that user wants to be a deaf
			// occupant
			packet.addExtension(new DeafExtension());
		}
	}
}