/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you 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.gecko.rsa.discovery;

import org.osgi.framework.BundleContext;
import org.osgi.framework.ServiceReference;
import org.osgi.service.remoteserviceadmin.EndpointEvent;
import org.osgi.service.remoteserviceadmin.EndpointEventListener;
import org.osgi.util.tracker.ServiceTracker;

/**
 * Tracks EndpointEventListeners. This means tracking the Topology-Managers, that needs to be informed
 * about new remote services that are announced from foreign frameworks.
 * 
 * Changes are delegated to the {@link ImportingEndpointEventManager}. This then handles the cache and the lifecycle of 
 * the descriptions that needs to be sent and the correct cache handling of all the topology managers
 * 
 * @author Mark Hoffmann
 * @since 06.07.2018
 */
public class ImportingTopologyManagerTracker extends ServiceTracker<EndpointEventListener, EndpointEventListener> {
	
    private final ImportingEndpointEventManager importingManager;

    public ImportingTopologyManagerTracker(BundleContext bctx, ImportingEndpointEventManager importingManager) {
        super(bctx, EndpointEventListener.class, null);
        this.importingManager = importingManager;
    }
    
    /* 
     * (non-Javadoc)
     * @see org.osgi.util.tracker.ServiceTracker#addingService(org.osgi.framework.ServiceReference)
     */
    @Override
    public EndpointEventListener addingService(ServiceReference<EndpointEventListener> topologyManagerRef) {
    	EndpointEventListener topologyManager = super.addingService(topologyManagerRef);
        importingManager.modifyTopologyManager(topologyManagerRef, topologyManager, EndpointEvent.ADDED);
        return topologyManager;
    }

    /* 
     * (non-Javadoc)
     * @see org.osgi.util.tracker.ServiceTracker#modifiedService(org.osgi.framework.ServiceReference, java.lang.Object)
     */
    @Override
    public void modifiedService(ServiceReference<EndpointEventListener> topologyManagerRef, EndpointEventListener topologyManager) {
        /* 
         * Called when an topology manager updates its service properties.
         * This usually happens, when the EndpointEventListener.ENDPOINT_LISTENER_SCOPE changes property
         * of the topology manager / endpoint event listener changes
         */
        importingManager.modifyTopologyManager(topologyManagerRef, topologyManager, EndpointEvent.MODIFIED);
    }

    /* 
     * (non-Javadoc)
     * @see org.osgi.util.tracker.ServiceTracker#removedService(org.osgi.framework.ServiceReference, java.lang.Object)
     */
    @Override
    public void removedService(ServiceReference<EndpointEventListener> topologyManagerRef, EndpointEventListener topologyManager) {
        importingManager.removeTopologyManager(topologyManagerRef);
        super.removedService(topologyManagerRef, topologyManager);
    }

}