/**
 * $RCSfile$
 * $Revision$
 * $Date$
 *
 * Copyright (C) 2004 Jive Software. All rights reserved.
 *
 * This software is published under the terms of the GNU Public License (GPL),
 * a copy of which is included in this distribution.
 */

package org.jivesoftware.messenger.net;

import org.dom4j.Element;
import org.dom4j.io.XPPPacketReader;
import org.jivesoftware.messenger.*;
import org.jivesoftware.messenger.audit.Auditor;
import org.jivesoftware.messenger.auth.UnauthorizedException;
import org.jivesoftware.util.LocaleUtils;
import org.jivesoftware.util.Log;
import org.xmlpull.v1.XmlPullParser;
import org.xmlpull.v1.XmlPullParserException;
import org.xmlpull.v1.XmlPullParserFactory;
import org.xmpp.packet.*;

import java.io.EOFException;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.Writer;
import java.net.Socket;
import java.net.SocketException;

/**
 * Reads XMPP XML from a socket.
 *
 * @author Derek DeMoro
 */
public class SocketReadThread extends Thread {

    /**
     * The utf-8 charset for decoding and encoding Jabber packet streams.
     */
    private static String CHARSET = "UTF-8";
    /**
     * Reuse the same factory for all the connections.
     */
    private static XmlPullParserFactory factory = null;

    private Socket sock;
    private Session session;
    private Connection connection;
    private String serverName;
    /**
     * Router used to route incoming packets to the correct channels.
     */
    private PacketRouter router;
    /**
     * Audits incoming data
     */
    private Auditor auditor;
    private boolean clearSignout = false;
    XPPPacketReader reader = null;

    static {
        try {
            factory = XmlPullParserFactory.newInstance();
        }
        catch (XmlPullParserException e) {
            Log.error("Error creating a parser factory", e);
        }
    }


    /**
     * Create dedicated read thread for this socket.
     *
     * @param router     The router for sending packets that were read
     * @param serverName The name of the server this socket is working for
     * @param auditor    The audit manager that will audit incoming packets
     * @param sock       The socket to read from
     * @param conn       The connection being read
     */
    public SocketReadThread(PacketRouter router, String serverName, Auditor auditor, Socket sock,
                            Connection conn) {
        super("SRT reader");
        this.serverName = serverName;
        this.router = router;
        this.auditor = auditor;
        this.connection = conn;
        this.sock = sock;
    }

    /**
     * A dedicated thread loop for reading the stream and sending incoming
     * packets to the appropriate router.
     */
    public void run() {
        try {
            reader = new XPPPacketReader();
            reader.setXPPFactory(factory);

            reader.getXPPParser().setInput(new InputStreamReader(sock.getInputStream(),
                    CHARSET));

            // Read in the opening tag and prepare for packet stream
            createSession();

            // Read the packet stream until it ends
            if (session != null) {
                readStream();
            }

        }
        catch (EOFException eof) {
            // Normal disconnect
        }
        catch (SocketException se) {
            // The socket was closed. The server may close the connection for several reasons (e.g.
            // user requested to remove his account). Do nothing here. 
        }
        catch (XmlPullParserException ie) {
            // Check if the user abruptly cut the connection without sending previously an
            // unavailable presence
            if (clearSignout == false) {
                if (session != null && session.getStatus() == Session.STATUS_AUTHENTICATED) {
                    if (session instanceof ClientSession) {
                        Presence presence = ((ClientSession) session).getPresence();
                        if (presence != null) {
                            // Simulate an unavailable presence sent by the user.
                            Presence packet = presence.createCopy();
                            packet.setType(Presence.Type.unavailable);
                            packet.setFrom(session.getAddress());
                            router.route(packet);
                            clearSignout = true;
                        }
                    }
                }
            }
            // It is normal for clients to abruptly cut a connection
            // rather than closing the stream document
            // Since this is normal behavior, we won't log it as an error
//            Log.error(LocaleUtils.getLocalizedString("admin.disconnect"),ie);
        }
        catch (Exception e) {
            if (session != null) {
                Log.warn(LocaleUtils.getLocalizedString("admin.error.stream"), e);
            }
        }
        finally {
            if (session != null) {
                Log.debug("Logging off " + session.getAddress() + " on " + connection);
                try {
                    // Allow everything to settle down after a disconnect
                    // e.g. presence updates to avoid sending double
                    // presence unavailable's
                    sleep(3000);
                    session.getConnection().close();
                }
                catch (Exception e) {
                    Log.warn(LocaleUtils.getLocalizedString("admin.error.connection")
                            + "\n" + sock.toString());
                }
            }
            else {
                Log.error(LocaleUtils.getLocalizedString("admin.error.connection")
                        + "\n" + sock.toString());
            }
        }
    }

    /**
     * Read the incoming stream until it ends. Much of the reading
     * will actually be done in the channel handlers as they run the
     * XPP through the data. This method mostly handles the idle waiting
     * for incoming data. To prevent clients from stalling channel handlers,
     * a watch dog timer is used. Packets that take longer than the watch
     * dog limit to read will cause the session to be closed.
     */
    private void readStream() throws Exception {
        while (true) {
            Element doc = reader.parseDocument().getRootElement();

            if (doc == null) {
                // Stop reading the stream since the client has sent an end of stream element and
                // probably closed the connection
                return;
            }

            String tag = doc.getName();
            if ("message".equals(tag)) {
                Message packet = null;
                try {
                    packet = new Message(doc);
                }
                catch(IllegalArgumentException e) {
                    // The original packet contains a malformed JID so answer an error
                    Message reply = new Message();
                    reply.setID(doc.attributeValue("id"));
                    reply.setTo(session.getAddress());
                    reply.getElement().addAttribute("from", doc.attributeValue("to"));
                    reply.setError(PacketError.Condition.jid_malformed);
                    session.process(reply);
                    continue;
                }
                packet.setFrom(session.getAddress());
                auditor.audit(packet, session);
                router.route(packet);
                session.incrementClientPacketCount();
            }
            else if ("presence".equals(tag)) {
                Presence packet = null;
                try {
                    packet = new Presence(doc);
                }
                catch(IllegalArgumentException e) {
                    // The original packet contains a malformed JID so answer an error
                    Presence reply = new Presence();
                    reply.setID(doc.attributeValue("id"));
                    reply.setTo(session.getAddress());
                    reply.getElement().addAttribute("from", doc.attributeValue("to"));
                    reply.setError(PacketError.Condition.jid_malformed);
                    session.process(reply);
                    continue;
                }
                packet.setFrom(session.getAddress());
                auditor.audit(packet, session);
                router.route(packet);
                session.incrementClientPacketCount();
                // Update the flag that indicates if the user made a clean sign out
                clearSignout = (Presence.Type.unavailable == packet.getType() ? true : false);
            }
            else if ("iq".equals(tag)) {
                IQ packet = null;
                try {
                    packet = getIQ(doc);
                }
                catch(IllegalArgumentException e) {
                    // The original packet contains a malformed JID so answer an error
                    IQ reply = new IQ();
                    if (!doc.elements().isEmpty()) {
                        reply.setChildElement(((Element) doc.elements().get(0)).createCopy());
                    }
                    reply.setID(doc.attributeValue("id"));
                    reply.setTo(session.getAddress());
                    if (doc.attributeValue("to") != null) {
                        reply.getElement().addAttribute("from", doc.attributeValue("to"));
                    }
                    reply.setError(PacketError.Condition.jid_malformed);
                    session.process(reply);
                    continue;
                }
                packet.setFrom(session.getAddress());
                auditor.audit(packet, session);
                router.route(packet);
                session.incrementClientPacketCount();
            }
            else {
                throw new XmlPullParserException(LocaleUtils.getLocalizedString("admin.error.packet.tag") + tag);
            }
        }
    }

    private IQ getIQ(Element doc) {
        Element query = doc.element("query");
        if (query != null && "jabber:iq:roster".equals(query.getNamespaceURI())) {
            return new Roster(doc);
        }
        else {
            return new IQ(doc);
        }
    }

    /**
     * Uses the XPP to grab the opening stream tag and create an active session
     * object. The session to create will depend on the sent namespace. In all
     * cases, the method obtains the opening stream tag, checks for errors, and
     * either creates a session or returns an error and kills the connection.
     * If the connection remains open, the XPP will be set to be ready for the
     * first packet. A call to next() should result in an START_TAG state with
     * the first packet in the stream.
     */
    private void createSession() throws UnauthorizedException, XmlPullParserException, IOException {
        XmlPullParser xpp = reader.getXPPParser();
        for (int eventType = xpp.getEventType(); eventType != XmlPullParser.START_TAG;) {
            eventType = xpp.next();
        }

        // Create the correct session based on the sent namespace
        if ("jabber:client".equals(xpp.getNamespace(null))) {
            // The connected client is a regular client so create a ClientSession
            session = ClientSession.createSession(serverName, reader, connection);
        }
        else if ("jabber:component:accept".equals(xpp.getNamespace(null))) {
            // The connected client is a component so create a ComponentSession
            session = ComponentSession.createSession(serverName, reader, connection);
        }
        else {
            Writer writer = connection.getWriter();
            StringBuilder sb = new StringBuilder();
            sb.append("<?xml version='1.0' encoding='");
            sb.append(CHARSET);
            sb.append("'?>");
            // Include the bad-namespace-prefix in the response
            sb.append("<stream:error>");
            sb.append("<bad-namespace-prefix xmlns=\"urn:ietf:params:xml:ns:xmpp-streams\"/>");
            sb.append("</stream:error>");
            sb.append("</stream:stream>");
            writer.write(sb.toString());
            writer.flush();
            // Close the underlying connection
            connection.close();
        }
    }
}
