/**
 * $RCSfile$
 * $Revision$
 * $Date$
 *
 * 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.Message;
import org.jivesoftware.smack.packet.Packet;
import org.jivesoftware.smack.packet.Presence;
import org.jivesoftware.smackx.packet.DiscoverInfo;
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 (XEP-0012) 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(&quot;jabber.org&quot;);
 * con.login(&quot;john&quot;, &quot;doe&quot;);
 * LastActivity activity = LastActivity.getLastActivity(con, &quot;xray@jabber.org/Smack&quot;);
 * </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, &quot;xray@jabber.org&quot;);
 * </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, &quot;jabber.org&quot;);
 * </pre>
 * 
 * @author Gabriel Guardincerri
 * @see <a href="http://xmpp.org/extensions/xep-0012.html">XEP-0012: Last
 *      Activity</a>
 */

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) {
                Presence presence = (Presence) packet;
                Presence.Mode mode = presence.getMode();
                if (mode == null) return;
                switch (mode) {
                case available:
                case chat:
                    // We assume that only a switch to available and chat indicates user activity
                    // since other mode changes could be also a result of some sort of automatism
                    resetIdleTime();
                }
            }
        }, new PacketTypeFilter(Presence.class));

        connection.addPacketListener(new PacketListener() {
            @Override
            public void processPacket(Packet packet) {
                Message message = (Message) packet;
                // if it's not an error message, reset the idle time
                if (message.getType() == Message.Type.error) return;
                resetIdleTime();
            }
        }, new PacketTypeFilter(Message.class));

        // 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)));
        ServiceDiscoveryManager.getInstanceFor(connection).addFeature(LastActivity.NAMESPACE);
        resetIdleTime();
    }

    /**
     * Resets the idle time to 0, this should be invoked when a new message is
     * sent.
     */
    private void resetIdleTime() {
        long now = System.currentTimeMillis();
        synchronized (this) {
            lastMessageSent = now;
        }
    }

    /**
     * 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 lms;
        long now = System.currentTimeMillis();
        synchronized (this) {
            lms = lastMessageSent;
        }
        return ((now - lms) / 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;
    }

    /**
     * Returns true if Last Activity (XEP-0012) is supported by a given JID
     * 
     * @param connection the connection to be used
     * @param jid a JID to be tested for Last Activity support
     * @return true if Last Activity is supported, otherwise false
     */
    public static boolean isLastActivitySupported(Connection connection, String jid) {
        try {
            DiscoverInfo result =
                ServiceDiscoveryManager.getInstanceFor(connection).discoverInfo(jid);
            return result.containsFeature(LastActivity.NAMESPACE);
        }
        catch (XMPPException e) {
            return false;
        }
    }
}