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 *     or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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package com.openexchange.push.udp.osgi;

import static com.openexchange.push.udp.registry.PushServiceRegistry.getServiceRegistry;
import java.util.ArrayList;
import java.util.Hashtable;
import java.util.List;
import org.osgi.framework.ServiceRegistration;
import org.osgi.service.event.EventAdmin;
import org.osgi.service.event.EventConstants;
import org.osgi.service.event.EventHandler;
import org.osgi.util.tracker.ServiceTracker;
import com.openexchange.config.ConfigurationService;
import com.openexchange.context.ContextService;
import com.openexchange.event.EventFactoryService;
import com.openexchange.folder.FolderService;
import com.openexchange.push.udp.PushHandler;
import com.openexchange.push.udp.PushInit;
import com.openexchange.push.udp.registry.RegistryCustomizer;
import com.openexchange.server.osgiservice.DeferredActivator;
import com.openexchange.server.osgiservice.ServiceRegistry;
import com.openexchange.timer.TimerService;

/**
 * {@link PushUDPActivator} - OSGi bundle activator for the push UDP.
 * 
 * @author <a href="mailto:sebastian.kauss@open-xchange.org">Sebastian Kauss</a>
 */
public class PushUDPActivator extends DeferredActivator {

    private static final org.apache.commons.logging.Log LOG = org.apache.commons.logging.LogFactory.getLog(PushUDPActivator.class);

    private ServiceRegistration registration;

    private final List<ServiceTracker> serviceTrackers;

    /**
     * Initializes a new {@link PushUDPActivator}.
     */
    public PushUDPActivator() {
        super();
        serviceTrackers = new ArrayList<ServiceTracker>(4);
    }

    @Override
    protected Class<?>[] getNeededServices() {
        return new Class<?>[] { ConfigurationService.class, EventAdmin.class, ContextService.class, FolderService.class };
    }

    @Override
    protected void handleUnavailability(final Class<?> clazz) {
        /*
         * Never stop the server even if a needed service is absent
         */
        if (LOG.isWarnEnabled()) {
            LOG.warn("Absent service: " + clazz.getName());
        }
        getServiceRegistry().removeService(clazz);
    }

    @Override
    protected void handleAvailability(final Class<?> clazz) {
        if (LOG.isInfoEnabled()) {
            LOG.info("Re-available service: " + clazz.getName());
        }
        getServiceRegistry().addService(clazz, getService(clazz));
    }

    @Override
    public void startBundle() throws Exception {
        try {
            /*
             * (Re-)Initialize service registry with available services
             */
            {
                final ServiceRegistry registry = getServiceRegistry();
                registry.clearRegistry();
                final Class<?>[] classes = getNeededServices();
                for (final Class<?> classe : classes) {
                    final Object service = getService(classe);
                    if (null != service) {
                        registry.addService(classe, service);
                    }
                }
            }
            /*
             * Start-up
             */
            PushInit.getInstance().start();
            addRegisterService();
            /*
             * Service trackers
             */
            serviceTrackers.add(new ServiceTracker(
                context,
                EventFactoryService.class.getName(),
                new RegistryCustomizer<EventFactoryService>(context, EventFactoryService.class)));
            serviceTrackers.add(new ServiceTracker(context, TimerService.class.getName(), new TimerCustomizer(context)));
            // Open service trackers
            for (final ServiceTracker tracker : serviceTrackers) {
                tracker.open();
            }
        } catch (final Exception e) {
            LOG.error(e.getMessage(), e);
            throw e;
        }
    }

    @Override
    public void stopBundle() throws Exception {
        try {
            /*
             * Close service trackers
             */
            for (final ServiceTracker tracker : serviceTrackers) {
                tracker.close();
            }
            serviceTrackers.clear();
            /*
             * Shut-down
             */
            dropRegisterService();
            PushInit.getInstance().stop();
            /*
             * Clear service registry
             */
            getServiceRegistry().clearRegistry();
        } catch (final Exception e) {
            LOG.error(e.getMessage(), e);
            throw e;
        }
    }

    protected void addRegisterService() {
        final String[] topics = new String[] { EventConstants.EVENT_TOPIC, "com/openexchange/*" };
        final Hashtable<Object, Object> ht = new Hashtable<Object, Object>();
        ht.put(EventConstants.EVENT_TOPIC, topics);
        registration = context.registerService(EventHandler.class.getName(), new PushHandler(), ht);
    }

    protected void dropRegisterService() {
        if (null != registration) {
            registration.unregister();
            registration = null;
        }
    }

}
