/**
 * $RCSfile$
 * $Revision: $
 * $Date: $
 *
 * Copyright 2003-2006 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.smackx;

import org.jivesoftware.smack.*;
import org.jivesoftware.smack.filter.AndFilter;
import org.jivesoftware.smack.filter.IQTypeFilter;
import org.jivesoftware.smack.filter.PacketIDFilter;
import org.jivesoftware.smack.filter.PacketTypeFilter;
import org.jivesoftware.smack.packet.IQ;
import org.jivesoftware.smack.packet.Packet;
import org.jivesoftware.smackx.packet.LastActivity;

/**
 * A last activity manager for handling information about the last activity associated
 * with a Jabber ID. A manager handles incoming LastActivity requests of existing
 * Connections. It also allows to request last activity information of other users.<p>
 *
 * LastActivity (JEP-012) based on the sending JID's type allows for retrieval of:
 * <ol>
 * <li>How long a particular user has been idle
 * <li>How long a particular user has been logged-out and the message the specified when doing so.
 * <li>How long a host has been up.
 * </ol>
 * <p/>
 *
 * For example to get the idle time of a user logged in a resource, simple send the
 * LastActivity packet to them, as in the following code:<p>
 *
 * <pre>
 * Connection con = new XMPPConnection("jabber.org");
 * con.login("john", "doe");
 * LastActivity activity = LastActivity.getLastActivity(con, "xray@jabber.org/Smack");
 * </pre>
 *
 * To get the lapsed time since the last user logout is the same as above but with
 * out the resource:
 * <pre>
 * LastActivity activity = LastActivity.getLastActivity(con, "xray@jabber.org");
 * </pre>
 *
 * To get the uptime of a host, you simple send the LastActivity packet to it, as in the
 * following code example:<p>
 *
 * <pre>
 * LastActivity activity = LastActivity.getLastActivity(con, "jabber.org");
 * </pre>
 *
 * @author Gabriel Guardincerri
 */

public class LastActivityManager {

    private long lastMessageSent;

    private Connection connection;

    // Enable the LastActivity support on every established connection
    static {
        Connection.addConnectionCreationListener(new ConnectionCreationListener() {
            public void connectionCreated(Connection connection) {
                new LastActivityManager(connection);
            }
        });
    }

    /**
     * Creates a last activity manager to response last activity requests.
     *
     * @param connection The Connection that the last activity requests will use.
     */
    private LastActivityManager(Connection connection) {
        this.connection = connection;

        // Listen to all the sent messages to reset the idle time on each one
        connection.addPacketSendingListener(new PacketListener() {
            public void processPacket(Packet packet) {
                resetIdleTime();
            }
        }, null);

        // Register a listener for a last activity query
        connection.addPacketListener(new PacketListener() {

            public void processPacket(Packet packet) {
                LastActivity message = new LastActivity();
                message.setType(IQ.Type.RESULT);
                message.setTo(packet.getFrom());
                message.setFrom(packet.getTo());
                message.setPacketID(packet.getPacketID());
                message.setLastActivity(getIdleTime());

                LastActivityManager.this.connection.sendPacket(message);
            }

        }, new AndFilter(new IQTypeFilter(IQ.Type.GET), new PacketTypeFilter(LastActivity.class)));
    }

    /**
     * Resets the idle time to 0, this should be invoked when a new message is
     * sent.
     */
    private void resetIdleTime() {
        lastMessageSent = System.currentTimeMillis();
    }

    /**
     * The idle time is the lapsed time between the last message sent and now.
     *
     * @return the lapsed time between the last message sent and now.
     */
    private long getIdleTime() {
        long now = System.currentTimeMillis();
        return ((now - lastMessageSent) / 1000);
    }

    /**
     * Returns the last activity of a particular jid. If the jid is a full JID
     * (i.e., a JID of the form of 'user@host/resource') then the last activity
     * is the idle time of that connected resource. On the other hand, when the
     * jid is a bare JID (e.g. 'user@host') then the last activity is the lapsed
     * time since the last logout or 0 if the user is currently logged in. Moreover,
     * when the jid is a server or component (e.g., a JID of the form 'host') the
     * last activity is the uptime.
     *
     * @param con the current Connection.
     * @param jid the JID of the user.
     * @return the LastActivity packet of the jid.
     * @throws XMPPException thrown if a server error has occured.
     */
    public static LastActivity getLastActivity(Connection con, String jid)
            throws XMPPException {
        LastActivity activity = new LastActivity();
        activity.setTo(jid);

        PacketCollector collector =
                con.createPacketCollector(new PacketIDFilter(activity.getPacketID()));
        con.sendPacket(activity);

        LastActivity response =
                (LastActivity) collector.nextResult(SmackConfiguration.getPacketReplyTimeout());

        // Cancel the collector.
        collector.cancel();
        if (response == null) {
            throw new XMPPException("No response from server on status set.");
        }
        if (response.getError() != null) {
            throw new XMPPException(response.getError());
        }
        return response;
	}

}