/**
 * Redistribution and use of this software and associated documentation
 * ("Software"), with or without modification, are permitted provided
 * that the following conditions are met:
 *
 * 1. Redistributions of source code must retain copyright
 *    statements and notices.  Redistributions must also contain a
 *    copy of this document.
 *
 * 2. Redistributions in binary form must reproduce the
 *    above copyright notice, this list of conditions and the
 *    following disclaimer in the documentation and/or other
 *    materials provided with the distribution.
 *
 * 3. The name "Exolab" must not be used to endorse or promote
 *    products derived from this Software without prior written
 *    permission of Exoffice Technologies.  For written permission,
 *    please contact info@exolab.org.
 *
 * 4. Products derived from this Software may not be called "Exolab"
 *    nor may "Exolab" appear in their names without prior written
 *    permission of Exoffice Technologies. Exolab is a registered
 *    trademark of Exoffice Technologies.
 *
 * 5. Due credit should be given to the Exolab Project
 *    (http://www.exolab.org/).
 *
 * THIS SOFTWARE IS PROVIDED BY EXOFFICE TECHNOLOGIES AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT
 * NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
 * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL
 * EXOFFICE TECHNOLOGIES OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * Copyright 2001-2005 (C) Exoffice Technologies Inc. All Rights Reserved.
 *
 * $Id: DestinationManager.java,v 1.2 2005/03/18 03:58:39 tanderson Exp $
 */
package org.exolab.jms.messagemgr;

import java.sql.Connection;
import java.sql.SQLException;
import java.util.Collections;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.Map;
import java.util.Vector;
import javax.jms.InvalidDestinationException;
import javax.jms.JMSException;
import javax.naming.Context;
import javax.naming.NamingException;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.exolab.jms.client.JmsDestination;
import org.exolab.jms.client.JmsQueue;
import org.exolab.jms.client.JmsTopic;
import org.exolab.jms.config.AdministeredDestinations;
import org.exolab.jms.config.AdministeredQueue;
import org.exolab.jms.config.AdministeredTopic;
import org.exolab.jms.config.ConfigurationManager;
import org.exolab.jms.config.Subscriber;
import org.exolab.jms.gc.GarbageCollectable;
import org.exolab.jms.gc.GarbageCollectionService;
import org.exolab.jms.message.MessageImpl;
import org.exolab.jms.persistence.DatabaseService;
import org.exolab.jms.persistence.PersistenceAdapter;
import org.exolab.jms.persistence.PersistenceException;
import org.exolab.jms.persistence.SQLHelper;
import org.exolab.jms.server.NamingHelper;
import org.exolab.jms.service.ServiceException;


/**
 * The destination manager is responsible for creating and managing the
 * lifecycle of {@link DestinationCache} objects. The destination manager is
 * also responsible for managing messages, that are received by the message
 * manager, which do not have any registered {@link DestinationCache}
 *
 * @author <a href="mailto:jima@comware.com.au">Jim Alateras</a>
 * @author <a href="mailto:tma@netspace.net.au">Tim Anderson</a>
 * @version $Revision: 1.2 $ $Date: 2005/03/18 03:58:39 $
 */
public class DestinationManager
        implements MessageManagerEventListener, GarbageCollectable {

    /**
     * This structure maintains a list of active caches.
     */
    private Map _caches = Collections.synchronizedMap(new HashMap());

    /**
     * The set of persistent and non-persistent destinations, keyed on name.
     */
    private HashMap _destinationCache = new HashMap();

    /**
     * Maintains a list of wildcard destinations, which can either be durable or
     * transient.
     */
    private LinkedList _wildcardDestinations = new LinkedList();

    /**
     * Maintains a linked list of DestinationEventListener objects. These
     * listeners will be informed when destinations are added or destroyed.
     */
    private LinkedList _listeners = new LinkedList();

    /**
     * Manage the singleton instance of the DestinationManager.
     */
    private static volatile DestinationManager _instance = null;

    /**
     * The logger.
     */
    private static final Log _log =
            LogFactory.getLog(DestinationManager.class);

    /**
     * Construct a new <code>DestinationManager</code>.
     *
     * @throws ServiceException if the service cannot be initialised
     */
    private DestinationManager() throws ServiceException {
        init();

        // register with the GarbageCollectionService
        GarbageCollectionService.instance().register(this);
    }

    /**
     * Create the singleton instance of the destination manager.
     *
     * @return the singleton instance
     * @throws ServiceException if the service cannot be initialised
     */
    public static DestinationManager createInstance() throws ServiceException {
        _instance = new DestinationManager();
        return _instance;
    }

    /**
     * Return the singleton destination manager.
     *
     * @return the singleton instance, or <code>null</code> if it hasn't been
     *         initialised
     */
    public static DestinationManager instance() {
        return _instance;
    }

    /**
     * Returns the cache for the supplied destination. If the cache doesn't
     * exist, it will be created, and any listeners notified.
     *
     * @param dest the destination of the cache to return
     * @return the cache associated with <code>dest</code>
     * @throws InvalidDestinationException if <code>dest</code> doesn't exist
     * @throws JMSException                if the cache can't be created
     */
    public DestinationCache getDestinationCache(JmsDestination dest)
            throws JMSException {
        DestinationCache result;
        try {
            result = getDestinationCache(dest, null);
        } catch (PersistenceException exception) {
            String msg = "Failed to create cache for destination "
                    + dest.getName();
            _log.error(msg, exception);
            throw new JMSException(msg + ": " + exception.getMessage());
        }
        return result;
    }

    /**
     * Returns the cache for the supplied destination. If the cache doesn't
     * exist, it will be created, and any listeners notified.
     *
     * @param dest the destination of the cache to return
     * @return the cache associated with <code>dest</code>
     * @throws InvalidDestinationException if <code>dest</code> doesn't exist
     * @throws JMSException                if the cache can't be created
     * @throws PersistenceException        for any persistence error
     */
    public synchronized DestinationCache getDestinationCache(
            JmsDestination dest, Connection connection) throws JMSException,
            PersistenceException {
        DestinationCache result = (DestinationCache) _caches.get(dest);
        if (result == null) {
            if (dest instanceof JmsTopic && ((JmsTopic) dest).isWildCard()) {
                throw new InvalidDestinationException(
                        "Cannot cache messages for wildcarded topic: "
                        + dest.getName());
            }

            JmsDestination existing = getDestination(dest.getName());
            if (existing == null) {
                throw new InvalidDestinationException(
                        "Destination does not exist: " + dest.getName());
            }
            if (existing.getPersistent()) {
                if (connection != null) {
                    result = createPersistentCache(existing, connection);
                } else {
                    result = createPersistentCache(existing);
                }
            } else {
                result = createNonPersistentCache(existing);
            }
            _caches.put(dest, result);

            // notify the listeners that a new destination has been added
            // to the destination manager
            notifyDestinationAdded(dest, result);
        }
        return result;
    }

    /**
     * Create a persistent {@link DestinationCache} for the specified
     * destination.
     *
     * @param dest       the destination to create the cache for
     * @param connection the database connection to use
     * @return a new cache
     * @throws JMSException         for any JMS error
     * @throws PersistenceException for any persistence error
     */
    protected DestinationCache createPersistentCache(JmsDestination dest,
                                                     Connection connection)
            throws JMSException, PersistenceException {

        DestinationCache result;
        if (dest instanceof JmsTopic) {
            result = new TopicDestinationCache((JmsTopic) dest, connection);
        } else {
            result = new QueueDestinationCache((JmsQueue) dest, connection);
        }
        return result;
    }

    /**
     * Create a persistent {@link DestinationCache} for the specified
     * destination.
     *
     * @param dest the destination to create the cache for
     * @return a new cache
     * @throws JMSException         if the cache cannot be created
     * @throws PersistenceException for any persistence error
     */
    protected DestinationCache createPersistentCache(JmsDestination dest)
            throws JMSException, PersistenceException {

        DestinationCache result;
        Connection connection = null;
        try {

            connection = DatabaseService.getConnection();
            result = createPersistentCache(dest, connection);
            connection.commit();
        } catch (JMSException exception) {
            SQLHelper.rollback(connection);
            throw exception;
        } catch (SQLException exception) {
            SQLHelper.rollback(connection);
            throw new PersistenceException(exception);
        } finally {
            SQLHelper.close(connection);
        }

        return result;
    }

    /**
     * Create a non-persistent {@link DestinationCache} for the specified
     * destination.
     *
     * @param dest the destination to create the cache for
     * @return a new cache
     * @throws JMSException if the cache cannot be created
     */
    protected DestinationCache createNonPersistentCache(JmsDestination dest)
            throws JMSException {

        DestinationCache result;
        if (dest instanceof JmsTopic) {
            result = new TopicDestinationCache((JmsTopic) dest);
        } else {
            result = new QueueDestinationCache((JmsQueue) dest);
        }

        // notify the listeners that a new destination has been added
        // to the destination manager
        notifyDestinationAdded(dest, result);
        _caches.put(dest, result);

        return result;
    }

    /**
     * Delete the specfied destination.
     *
     * @param cache the destination to destroy
     */
    protected void destroyDestinationCache(DestinationCache cache) {
        destroyDestinationCache(cache.getDestination());