Copyright (c) 2005, 2016 IBM Corporation and others.
This program and the accompanying materials
are made available under the terms of the Eclipse Public License 2.0
which accompanies this distribution, and is available at
https://www.eclipse.org/legal/epl-2.0/
SPDX-License-Identifier: EPL-2.0
Contributors:
    IBM Corporation - initial API and implementation
/*******************************************************************************
 * Copyright (c) 2005, 2016 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 * 
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.osgi.internal.log;

import java.util.*;
import org.osgi.framework.*;
import org.osgi.util.tracker.ServiceTracker;
import org.osgi.util.tracker.ServiceTrackerCustomizer;

public class EventAdminAdapter implements ServiceTrackerCustomizer<Object, Object> {
	public static final String EVENT_TOPIC = "event.topics"; //$NON-NLS-1$
	private static final String[] LOG_TOPICS_ARRAY = {"*", "org/*", "org/osgi/*", "org/osgi/service/*", "org/osgi/service/log/*", "org/osgi/service/log/LogEntry/*", "org/osgi/service/log/LogEntry/LOG_ERROR", "org/osgi/service/log/LogEntry/LOG_WARNING", "org/osgi/service/log/LogEntry/LOG_INFO", "org/osgi/service/log/LogEntry/LOG_DEBUG", "org/osgi/service/log/LogEntry/LOG_OTHER"}; //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$ //$NON-NLS-4$ //$NON-NLS-5$ //$NON-NLS-6$ //$NON-NLS-7$ //$NON-NLS-8$ //$NON-NLS-9$//$NON-NLS-10$ //$NON-NLS-11$
	private static final Object LOG_TOPIC_TOKEN = new Object();
	private static Collection<String> logTopics = new HashSet<>(Arrays.asList(LOG_TOPICS_ARRAY));
	private static Collection<String> eventAdminObjectClass = Arrays.asList("org.osgi.service.event.EventAdmin"); //$NON-NLS-1$
	private static Collection<String> eventHandlerObjectClass = Arrays.asList("org.osgi.service.event.EventHandler"); //$NON-NLS-1$

	private ServiceTracker<Object, Object> eventAdminTracker;
	private ServiceTracker<Object, Object> eventHandlerTracker;
	private BundleContext context;
	private ServiceReference<Object> eventAdmin;
	private int logEventHandlers;
	private ExtendedLogReaderServiceFactory logReaderServiceFactory;
	private EventAdminLogListener logListener;

	public EventAdminAdapter(BundleContext context, ExtendedLogReaderServiceFactory logReaderServiceFactory) {
		this.context = context;
		this.logReaderServiceFactory = logReaderServiceFactory;
		eventAdminTracker = new ServiceTracker<>(context, "org.osgi.service.event.EventAdmin", this); //$NON-NLS-1$
		eventHandlerTracker = new ServiceTracker<>(context, "org.osgi.service.event.EventHandler", this); //$NON-NLS-1$
	}

	public void start() {
		eventAdminTracker.open();
		eventHandlerTracker.open();
	}

	public void stop() {
		eventAdminTracker.close();
		eventHandlerTracker.close();
	}

	@Override
	public Object addingService(ServiceReference<Object> reference) {
		Object toTrack = null;
		Object objectClass = reference.getProperty(Constants.OBJECTCLASS);
		Object topics = reference.getProperty(EVENT_TOPIC);
		if (checkServiceProp(objectClass, eventAdminObjectClass) && eventAdmin == null) {
			toTrack = reference;
			eventAdmin = reference;
		} else if (checkServiceProp(objectClass, eventHandlerObjectClass) && checkServiceProp(topics, logTopics)) {
			logEventHandlers++;
			toTrack = LOG_TOPIC_TOKEN;
		}

		if (eventAdmin != null && logEventHandlers > 0 && logListener == null) {
			try {
				logListener = new EventAdminLogListener(context.getService(eventAdmin));
			} catch (ClassNotFoundException | NoSuchMethodException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
			logReaderServiceFactory.addLogListener(logListener, ExtendedLogReaderServiceFactory.NULL_LOGGER_FILTER);
		}

		return toTrack;
	}

	@Override
	public void modifiedService(ServiceReference<Object> reference, Object tracked) {
		removedService(reference, tracked);
		addingService(reference);
	}

	@Override
	public void removedService(ServiceReference<Object> reference, Object tracked) {
		if (tracked == eventAdmin) {
			eventAdmin = null;
			context.ungetService(reference);
		} else if (LOG_TOPIC_TOKEN == tracked) {
			logEventHandlers--;
		}

		if (logListener != null && (eventAdmin == null || logEventHandlers == 0)) {
			logReaderServiceFactory.removeLogListener(logListener);
			logListener = null;
		}
	}

	private static boolean checkServiceProp(Object property, Collection<String> check) {
		if (property instanceof String)
			return check.contains(property);

		if (property instanceof String[]) {
			String[] topics = (String[]) property;
			for (String topic : topics) {
				if (check.contains(topic)) {
					return true;
				}
			}
		}

		if (property instanceof Collection) {
			for (Object prop : (Collection<?>) property)
				if (check.contains(prop))
					return true;
		}
		return false;
	}
}