/*
 * Copyright (C) 2004-2008 Jive Software. All rights reserved.
 *
 * Licensed 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.jivesoftware.openfire.pep;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.concurrent.locks.Lock;

import org.jivesoftware.database.DbConnectionManager;
import org.jivesoftware.openfire.XMPPServer;
import org.jivesoftware.openfire.pubsub.CollectionNode;
import org.jivesoftware.openfire.pubsub.Node;
import org.jivesoftware.openfire.pubsub.PubSubEngine;
import org.jivesoftware.openfire.user.UserManager;
import org.jivesoftware.util.cache.Cache;
import org.jivesoftware.util.cache.CacheFactory;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.xmpp.packet.IQ;
import org.xmpp.packet.JID;

/**
 * Manages the creation, persistence and removal of {@link PEPService}
 * instances.
 * 
 * @author Guus der Kinderen, guus.der.kinderen@gmail.com
 * 
 */
public class PEPServiceManager {

    public static final Logger Log = LoggerFactory
            .getLogger(PEPServiceManager.class);

    private final static String GET_PEP_SERVICE = "SELECT DISTINCT serviceID FROM ofPubsubNode WHERE serviceID=?";

    /**
     * Cache of PEP services. Table, Key: bare JID (String); Value: PEPService
     */
    private final Cache<String, PEPService> pepServices = CacheFactory
            .createLocalCache("PEPServiceManager");

    private PubSubEngine pubSubEngine = null;

    /**
     * Retrieves a PEP service -- attempting first from memory, then from the
     * database.
     *
     * @param jid
     *            the JID of the user that owns the PEP service.
     * @return the requested PEP service if found or null if not found.
     */
    public PEPService getPEPService(JID jid) {
        return getPEPService( jid.toBareJID() );
    }

    /**
     * Retrieves a PEP service -- attempting first from memory, then from the
     * database.
     * 
     * @param jid
     *            the bare JID of the user that owns the PEP service.
     * @return the requested PEP service if found or null if not found.
     */
    public PEPService getPEPService(String jid) {
        PEPService pepService = null;

        final Lock lock = CacheFactory.getLock(jid, pepServices);
        try {
            lock.lock();
            if (pepServices.containsKey(jid)) {
                // lookup in cache
                pepService = pepServices.get(jid);
            } else {
                // lookup in database.
                pepService = loadPEPServiceFromDB(jid);
                
                // always add to the cache, even if it doesn't exist. This will
                // prevent future database lookups.
                pepServices.put(jid, pepService);
            }
        } finally {
            lock.unlock();
        }

        return pepService;
    }

    public PEPService create(JID owner) {
        // Return an error if the packet is from an anonymous, unregistered user
        // or remote user
        if (!XMPPServer.getInstance().isLocal(owner)
                || !UserManager.getInstance().isRegisteredUser(owner.getNode())) {
            throw new IllegalArgumentException(
                    "Request must be initiated by a local, registered user, but is not: "
                            + owner);
        }

        PEPService pepService = null;
        final String bareJID = owner.toBareJID();
        final Lock lock = CacheFactory.getLock(owner, pepServices);
        try {
            lock.lock();

            pepService = pepServices.get(bareJID);
            if (pepService == null) {
                pepService = new PEPService(XMPPServer.getInstance(), bareJID);
                pepServices.put(bareJID, pepService);

                if (Log.isDebugEnabled()) {
                    Log.debug("PEPService created for : " + bareJID);
                }
            }
        } finally {
            lock.unlock();
        }

        return pepService;
    }

    /**
     * Loads a PEP service from the database, if it exists.
     * 
     * @param jid
     *            the JID of the owner of the PEP service.
     * @return the loaded PEP service, or null if not found.
     */
    private PEPService loadPEPServiceFromDB(String jid) {
        PEPService pepService = null;

        Connection con = null;
        PreparedStatement pstmt = null;
        ResultSet rs = null;
        try {
            con = DbConnectionManager.getConnection();
            // Get all PEP services
            pstmt = con.prepareStatement(GET_PEP_SERVICE);
            pstmt.setString(1, jid);
            rs = pstmt.executeQuery();
            // Restore old PEPServices
            while (rs.next()) {
                String serviceID = rs.getString(1);

                // Create a new PEPService
                pepService = new PEPService(XMPPServer.getInstance(), serviceID);
                pepServices.put(serviceID, pepService);
                pubSubEngine.start(pepService);

                if (Log.isDebugEnabled()) {
                    Log.debug("PEP: Restored service for " + serviceID
                            + " from the database.");
                }
            }
        } catch (SQLException sqle) {
            Log.error(sqle.getMessage(), sqle);
        } finally {
            DbConnectionManager.closeConnection(rs, pstmt, con);
        }

        return pepService;
    }

    /**
     * Deletes the {@link PEPService} belonging to the specified owner.
     * 
     * @param owner
     *            The JID of the owner of the service to be deleted.
     */
    public void remove(JID owner) {
        PEPService service = null;

        final Lock lock = CacheFactory.getLock(owner, pepServices);
        try {
            lock.lock();
            service = pepServices.remove(owner.toBareJID());
        } finally {
            lock.unlock();
        }

        if (service == null) {
            return;
        }

        // Delete the user's PEP nodes from memory and the database.
        CollectionNode rootNode = service.getRootCollectionNode();
        for (final Node node : service.getNodes()) {
            if (rootNode.isChildNode(node)) {
                node.delete();
            }
        }
        rootNode.delete();
    }

    public void start(PEPService pepService) {
        pubSubEngine.start(pepService);
    }

    public void start() {
        pubSubEngine = new PubSubEngine(XMPPServer.getInstance()
                .getPacketRouter());
    }

    public void stop() {

        for (PEPService service : pepServices.values()) {
            pubSubEngine.shutdown(service);
        }

        pubSubEngine = null;
    }

    public void process(PEPService service, IQ iq) {
        pubSubEngine.process(service, iq);
    }
    
    public boolean hasCachedService(JID owner) {
        return pepServices.get(owner.toBareJID()) != null;
    }
    
    // mimics Shutdown, without killing the timer.
    public void unload(PEPService service) {	
        pubSubEngine.shutdown(service);
    }
}
