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 *    Please make sure that third-party modules and libraries are used
 *    according to their respective licenses.
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 *
 *     This program is free software; you can redistribute it and/or modify it
 *     under the terms of the GNU General Public License, Version 2 as published
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 *     WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 *     or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
 *     for more details.
 *
 *     You should have received a copy of the GNU General Public License along
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 */

package com.openexchange.mail.cache;

import java.util.Dictionary;
import java.util.Hashtable;
import java.util.Map;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.osgi.framework.BundleContext;
import org.osgi.framework.ServiceRegistration;
import org.osgi.service.event.Event;
import org.osgi.service.event.EventConstants;
import org.osgi.service.event.EventHandler;
import com.openexchange.event.impl.osgi.EventHandlerRegistration;
import com.openexchange.mail.MailException;
import com.openexchange.session.Session;
import com.openexchange.sessiond.SessiondEventConstants;

/**
 * {@link MailAccessCacheEventListener} - Listens for removed session containers to dispose its cached mail access instances.
 * 
 * @author <a href="mailto:thorben.betten@open-xchange.com">Thorben Betten</a>
 */
public final class MailAccessCacheEventListener implements EventHandlerRegistration {

    private static final Log LOG = LogFactory.getLog(MailAccessCacheEventListener.class);

    private ServiceRegistration serviceRegistration;

    public MailAccessCacheEventListener() {
        super();
    }

    public void handleEvent(final Event event) {
        final String topic = event.getTopic();
        if (SessiondEventConstants.TOPIC_REMOVE_DATA.equals(topic) || SessiondEventConstants.TOPIC_REMOVE_CONTAINER.equals(topic)) {
            final @SuppressWarnings("unchecked") Map<String, Session> sessions =
                (Map<String, Session>) event.getProperty(SessiondEventConstants.PROP_CONTAINER);
            final MailAccessCache mac;
            try {
                mac = MailAccessCache.getInstance();
            } catch (final MailException e) {
                LOG.error("Mail access cache could not be obtained.", e);
                return;
            }
            for (final Session session : sessions.values()) {
                try {
                    mac.clearUserEntries(session);
                    if (LOG.isInfoEnabled()) {
                        LOG.info(new StringBuilder(128).append("Detected timed-out session: ").append(session.getSessionID()).append(
                            ". Removed all possibly cached mail access instances for user ").append(session.getUserId()).append(
                            " in context ").append(session.getContextId()).toString());
                    }
                } catch (final MailException e) {
                    LOG.error("Unable to clear cached mail access for session: " + session.getSessionID(), e);
                }
            }
        } else if (SessiondEventConstants.TOPIC_REMOVE_SESSION.equals(topic)) {
            final Session session = (Session) event.getProperty(SessiondEventConstants.PROP_SESSION);
            final MailAccessCache mac;
            try {
                mac = MailAccessCache.getInstance();
            } catch (final MailException e) {
                LOG.error("Mail access cache could not be obtained.", e);
                return;
            }
            try {
                mac.clearUserEntries(session);
                if (LOG.isInfoEnabled()) {
                    LOG.info(new StringBuilder(128).append("Detected timed-out session: ").append(session.getSessionID()).append(
                        ". Removed all possibly cached mail access instances for user ").append(session.getUserId()).append(
                        " in context ").append(session.getContextId()).toString());
                }
            } catch (final MailException e) {
                LOG.error("Unable to clear cached mail access for session: " + session.getSessionID(), e);
            }
        }
    }

    public void registerService(final BundleContext context) {
        final Dictionary<String, Object> serviceProperties = new Hashtable<String, Object>(1);
        serviceProperties.put(EventConstants.EVENT_TOPIC, new String[] { SessiondEventConstants.TOPIC_REMOVE_DATA, SessiondEventConstants.TOPIC_REMOVE_CONTAINER, SessiondEventConstants.TOPIC_REMOVE_SESSION });
        serviceRegistration = context.registerService(EventHandler.class.getName(), this, serviceProperties);
    }

    public void unregisterService() {
        if (null != serviceRegistration) {
            serviceRegistration.unregister();
            serviceRegistration = null;
        }
    }
}
