/*
 * Copyright (C) 2015 Tom Evans. 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.openfire.websocket;

import org.dom4j.Element;
import org.jivesoftware.openfire.SessionPacketRouter;
import org.jivesoftware.openfire.multiplex.UnknownStanzaException;
import org.jivesoftware.openfire.session.LocalClientSession;
import org.jivesoftware.openfire.streammanagement.StreamManager;
import org.jivesoftware.util.JiveGlobals;

/**
 * This class extends Openfire's session packet router with the ACK capabilities
 * specified by XEP-0198: Stream Management.
 * 
 * NOTE: This class does NOT support the XEP-0198 stream resumption capabilities.
 * 
 * XEP-0198 allows either party (client or server) to send unsolicited ack/answer
 * stanzas on a periodic basis. This implementation approximates BOSH ack behavior
 * by sending unsolicited <a /> stanzas from the server to the client after a
 * configurable number of stanzas have been received from the client. 
 * 
 * Setting the system property to "1" would indicate that each client packet should 
 * be ack'd by the server when stream management is enabled for a particular stream. 
 * To disable unsolicited server acks, use the default value for system property
 * "stream.management.unsolicitedAckFrequency" ("0"). This setting does not affect
 * server responses to explicit ack requests from the client.
 */
public class StreamManagementPacketRouter extends SessionPacketRouter {

	public static final String SM_UNSOLICITED_ACK_FREQUENCY = "stream.management.unsolicitedAckFrequency";
	static {
		JiveGlobals.migrateProperty(SM_UNSOLICITED_ACK_FREQUENCY);
	}
	
	private int unsolicitedAckFrequency = JiveGlobals.getIntProperty(SM_UNSOLICITED_ACK_FREQUENCY, 0);
	
	public StreamManagementPacketRouter(LocalClientSession session) {
		super(session);
	}

	@Override
	public void route(Element wrappedElement) throws UnknownStanzaException {
		
		if (StreamManager.NAMESPACE_V3.equals(wrappedElement.getNamespace().getStringValue())) {
			session.getStreamManager().process( wrappedElement, session.getAddress() );
        } else {
        	super.route(wrappedElement);
			if (isUnsolicitedAckExpected()) {
				session.getStreamManager().sendServerAcknowledgement();
			}
		}
	}

	private boolean isUnsolicitedAckExpected() {
		if (!session.getStreamManager().isEnabled()) {
			return false;
		}
		return unsolicitedAckFrequency > 0 && session.getNumClientPackets() % unsolicitedAckFrequency == 0;
	}

}