/**
 * $RCSfile$
 * $Revision$
 * $Date$
 *
 * Copyright 2003-2004 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.smack;

import org.xmlpull.v1.*;

import java.util.*;
import java.util.List;

import org.jivesoftware.smack.packet.*;
import org.jivesoftware.smack.packet.XMPPError;
import org.jivesoftware.smack.filter.PacketFilter;
import org.jivesoftware.smack.util.*;
import org.jivesoftware.smack.provider.*;

/**
 * Listens for XML traffic from the XMPP server and parses it into packet objects.
 * The packet reader also manages all packet listeners and collectors.<p>
 *
 * @see PacketCollector
 * @see PacketListener
 * @author Matt Tucker
 */
class PacketReader {

    private Thread readerThread;
    private Thread listenerThread;

    private XMPPConnection connection;
    private XmlPullParser parser;
    private boolean done = false;
    protected List collectors = new ArrayList();
    private List listeners = new ArrayList();
    protected List connectionListeners = new ArrayList();

    private String connectionID = null;
    private Object connectionIDLock = new Object();

    protected PacketReader(XMPPConnection connection) {
        this.connection = connection;

        readerThread = new Thread() {
            public void run() {
                parsePackets();
            }
        };
        readerThread.setName("Smack Packet Reader");
        readerThread.setDaemon(true);

        listenerThread = new Thread() {
            public void run() {
                processListeners();
            }
        };
        listenerThread.setName("Smack Listener Processor");
        listenerThread.setDaemon(true);

        try {
            XmlPullParserFactory factory = XmlPullParserFactory.newInstance(
                    "org.xmlpull.mxp1.MXParserFactory", null);
            factory.setNamespaceAware(true);
            parser = factory.newPullParser();
            parser.setInput(connection.reader);
        }
        catch (XmlPullParserException xppe) {
            xppe.printStackTrace();
        }
    }

    /**
     * Creates a new packet collector for this reader. A packet filter determines
     * which packets will be accumulated by the collector.
     *
     * @param packetFilter the packet filter to use.
     * @return a new packet collector.
     */
    public PacketCollector createPacketCollector(PacketFilter packetFilter) {
        PacketCollector packetCollector = new PacketCollector(this, packetFilter);
        return packetCollector;
    }

    /**
     * Registers a packet listener with this reader. A packet filter determines
     * which packets will be delivered to the listener.
     *
     * @param packetListener the packet listener to notify of new packets.
     * @param packetFilter the packet filter to use.
     */
    public void addPacketListener(PacketListener packetListener, PacketFilter packetFilter) {
        ListenerWrapper wrapper = new ListenerWrapper(this, packetListener,
                packetFilter);
        synchronized (listeners) {
            listeners.add(wrapper);
        }
    }

    /**
     * Removes a packet listener.
     *
     * @param packetListener the packet listener to remove.
     */
    public void removePacketListener(PacketListener packetListener) {
        synchronized (listeners) {
            for (int i=0; i<listeners.size(); i++) {
                ListenerWrapper wrapper = (ListenerWrapper)listeners.get(i);
                if (wrapper != null && wrapper.packetListener.equals(packetListener)) {
                    listeners.set(i, null);
                }
            }
        }
    }

    /**
     * Starts the packet reader thread and returns once a connection to the server
     * has been established. A connection will be attempted for a maximum of five
     * seconds. An XMPPException will be thrown if the connection fails.
     *
     * @throws XMPPException if the server fails to send an opening stream back
     *      for more than five seconds.
     */
    public void startup() throws XMPPException {
        readerThread.start();
        listenerThread.start();
        // Wait for stream tag before returing. We'll wait a couple of seconds before
        // giving up and throwing an error.
        try {
            synchronized(connectionIDLock) {
                connectionIDLock.wait(SmackConfiguration.getPacketReplyTimeout());
            }
        }
        catch (InterruptedException ie) { }
        if (connectionID == null) {
            throw new XMPPException("Connection failed. No response from server.");
        }
        else {
            connection.connectionID = connectionID;
        }
    }

    /**
     * Shuts the packet reader down.
     */
    public void shutdown() {
        // Notify connection listeners of the connection closing if done hasn't already been set.
        if (!done) {
            ArrayList listenersCopy;
            synchronized (connectionListeners) {
                // Make a copy since it's possible that a listener will be removed from the list
                listenersCopy = new ArrayList(connectionListeners);
                for (Iterator i=listenersCopy.iterator(); i.hasNext(); ) {
                    ConnectionListener listener = (ConnectionListener)i.next();
                    listener.connectionClosed();
                }
            }
        }
        done = true;
    }

    /**
     * Sends out a notification that there was an error with the connection
     * and closes the connection.
     *
     * @param e the exception that causes the connection close event.
     */
    void notifyConnectionError(Exception e) {
        done = true;
        connection.close();
        // Notify connection listeners of the error.
        ArrayList listenersCopy;
        synchronized (connectionListeners) {
            // Make a copy since it's possible that a listener will be removed from the list
            listenersCopy = new ArrayList(connectionListeners);
            for (Iterator i=listenersCopy.iterator(); i.hasNext(); ) {
                ConnectionListener listener = (ConnectionListener)i.next();
                listener.connectionClosedOnError(e);
            }
        }
    }

    /**
     * Process listeners.
     */
    private void processListeners() {
        boolean processedPacket = false;
        while (!done) {
            synchronized (listeners) {
                if (listeners.size() > 0) {
                    for (int i=listeners.size()-1; i>=0; i--) {
                        if (listeners.get(i) == null) {
                            listeners.remove(i);
                        }
                    }
                }
            }
            processedPacket = false;
            int size = listeners.size();
            for (int i=0; i<size; i++) {
                ListenerWrapper wrapper = (ListenerWrapper)listeners.get(i);
                if (wrapper != null) {
                    processedPacket = processedPacket || wrapper.notifyListener();
                }
            }
            if (!processedPacket) {
                try {
                    Thread.sleep(100);
                }
                catch (InterruptedException ie) { }
            }
        }
    }

    /**
     * Parse top-level packets in order to process them further.
     */
    private void parsePackets() {
        try {
            int eventType = parser.getEventType();
            do {
                if (eventType == XmlPullParser.START_TAG) {
                    if (parser.getName().equals("message")) {
                        processPacket(PacketParserUtils.parseMessage(parser));
                    }
                    else if (parser.getName().equals("iq")) {
                        processPacket(parseIQ(parser));
                    }
                    else if (parser.getName().equals("presence")) {
                        processPacket(PacketParserUtils.parsePresence(parser));
                    }
                    // We found an opening stream. Record information about it, then notify
                    // the connectionID lock so that the packet reader startup can finish.
                    else if (parser.getName().equals("stream")) {
                        // Ensure the correct jabber:client namespace is being used.
                        if ("jabber:client".equals(parser.getNamespace(null))) {
                            // Get the connection id.
                            for (int i=0; i<parser.getAttributeCount(); i++) {
                                if (parser.getAttributeName(i).equals("id")) {
                                    // Save the connectionID and notify that we've gotten it.
                                    connectionID = parser.getAttributeValue(i);
                                    synchronized(connectionIDLock) {
                                        connectionIDLock.notifyAll();
                                    }
                                }
                                else if (parser.getAttributeName(i).equals("from")) {
                                    // Use the server name that the server says that it is.
                                    connection.host = parser.getAttributeValue(i);
                                }
                            }
                        }
                    }
                }
                else if (eventType == XmlPullParser.END_TAG) {
                    if (parser.getName().equals("stream")) {
                        // Close the connection.
                        connection.close();
                    }
                }
                eventType = parser.next();
            } while (!done && eventType != XmlPullParser.END_DOCUMENT);
        }
        catch (Exception e) {
            if (!done) {
                // Close the connection and notify connection listeners of the
                // error.
                notifyConnectionError(e);
            }
        }
    }

    /**
     * Processes a packet after it's been fully parsed by looping through the installed
     * packet collectors and listeners and letting them examine the packet to see if
     * they are a match with the filter.
     *
     * @param packet the packet to process.
     */
    private void processPacket(Packet packet) {
        if (packet == null) {
            return;
        }

        // Remove all null values from the collectors list.
        synchronized (collectors) {
            for (int i=collectors.size()-1; i>=0; i--) {
                    if (collectors.get(i) == null) {
                        collectors.remove(i);
                    }
                }
        }

        // Loop through all collectors and notify the appropriate ones.
        int size = collectors.size();
        for (int i=0; i<size; i++) {
            PacketCollector collector = (PacketCollector)collectors.get(i);
            if (collector != null) {
                // Have the collector process the packet to see if it wants to handle it.
                collector.processPacket(packet);
            }
        }
    }

    /**
     * Parses an IQ packet.
     *
     * @param parser the XML parser, positioned at the start of an IQ packet.
     * @return an IQ object.
     * @throws Exception if an exception occurs while parsing the packet.
     */
    private IQ parseIQ(XmlPullParser parser) throws Exception {
        IQ iqPacket = null;

        String id = parser.getAttributeValue("", "id");
        String to = parser.getAttributeValue("", "to");
        String from = parser.getAttributeValue("", "from");
        IQ.Type type = IQ.Type.fromString(parser.getAttributeValue("", "type"));
        XMPPError error = null;

        boolean done = false;
        while (!done) {
            int eventType = parser.next();

            if (eventType == XmlPullParser.START_TAG) {
                String elementName = parser.getName();
                String namespace = parser.getNamespace();
                if (elementName.equals("error")) {
                    error = PacketParserUtils.parseError(parser);
                }
                else if (elementName.equals("query") && namespace.equals("jabber:iq:auth")) {
                    iqPacket = parseAuthentication(parser);
                }
                else if (elementName.equals("query") && namespace.equals("jabber:iq:roster")) {
                    iqPacket = parseRoster(parser);
                }
                else if (elementName.equals("query") && namespace.equals("jabber:iq:register")) {
                    iqPacket = parseRegistration(parser);
                }
                // Otherwise, see if there is a registered provider for
                // this element name and namespace.
                else {
                    Object provider = ProviderManager.getIQProvider(elementName, namespace);
                    if (provider != null) {
                        if (provider instanceof IQProvider) {
                            iqPacket = ((IQProvider)provider).parseIQ(parser);
                        }
                        else if (provider instanceof Class) {
                            iqPacket = (IQ)PacketParserUtils.parseWithIntrospection(elementName,
                                    (Class)provider, parser);
                        }
                    }
                }
            }
            else if (eventType == XmlPullParser.END_TAG) {
                if (parser.getName().equals("iq")) {
                    done = true;
                }
            }
        }
        // Decide what to do when an IQ packet was not understood
        if (iqPacket == null) {
            if (IQ.Type.GET == type || IQ.Type.SET == type ) {
                // If the IQ stanza is of type "get" or "set" containing a child element
                // qualified by a namespace it does not understand, then answer an IQ of
                // type "error" with code 501 ("feature-not-implemented")
                iqPacket = new IQ() {
                    public String getChildElementXML() {
                        return null;
                    }
                };
                iqPacket.setPacketID(id);
                iqPacket.setTo(from);
                iqPacket.setFrom(to);
                iqPacket.setType(IQ.Type.ERROR);
                iqPacket.setError(new XMPPError(501, "feature-not-implemented"));
                connection.sendPacket(iqPacket);
                return null;
            }
            else {
                // If an IQ packet wasn't created above, create an empty IQ packet.
                iqPacket = new IQ() {
                    public String getChildElementXML() {
                        return null;
                    }
                };
            }
        }

        // Set basic values on the iq packet.
        iqPacket.setPacketID(id);
        iqPacket.setTo(to);
        iqPacket.setFrom(from);
        iqPacket.setType(type);
        iqPacket.setError(error);

        return iqPacket;
    }

    private Authentication parseAuthentication(XmlPullParser parser) throws Exception {
        Authentication authentication = new Authentication();
        boolean done = false;
        while (!done) {
            int eventType = parser.next();
            if (eventType == XmlPullParser.START_TAG) {
                if (parser.getName().equals("username")) {
                    authentication.setUsername(parser.nextText());
                }
                else if (parser.getName().equals("password")) {
                    authentication.setPassword(parser.nextText());
                }
                else if (parser.getName().equals("digest")) {
                    authentication.setDigest(parser.nextText());
                }
                else if (parser.getName().equals("resource")) {
                    authentication.setResource(parser.nextText());
                }
            }
            else if (eventType == XmlPullParser.END_TAG) {
                if (parser.getName().equals("query")) {
                    done = true;
                }
            }
        }
        return authentication;
    }

    private RosterPacket parseRoster(XmlPullParser parser) throws Exception {
        RosterPacket roster = new RosterPacket();
        boolean done = false;
        RosterPacket.Item item = null;
        while (!done) {
            int eventType = parser.next();
            if (eventType == XmlPullParser.START_TAG) {
                if (parser.getName().equals("item")) {
                    String jid = parser.getAttributeValue("", "jid");
                    String name = parser.getAttributeValue("", "name");
                    // Create packet.
                    item = new RosterPacket.Item(jid, name);
                    // Set status.
                    String ask = parser.getAttributeValue("", "ask");
                    RosterPacket.ItemStatus status = RosterPacket.ItemStatus.fromString(ask);
                    item.setItemStatus(status);
                    // Set type.
                    String subscription = parser.getAttributeValue("", "subscription");
                    RosterPacket.ItemType type = RosterPacket.ItemType.fromString(subscription);
                    item.setItemType(type);
                }
                if (parser.getName().equals("group")) {
                    String groupName = parser.nextText();
                    item.addGroupName(groupName);
                }
            }
            else if (eventType == XmlPullParser.END_TAG) {
                if (parser.getName().equals("item")) {
                    roster.addRosterItem(item);
                }
                if (parser.getName().equals("query")) {
                    done = true;
                }
            }
        }
        return roster;
    }

     private Registration parseRegistration(XmlPullParser parser) throws Exception {
        Registration registration = new Registration();
        Map fields = null;
        boolean done = false;
        while (!done) {
            int eventType = parser.next();
            if (eventType == XmlPullParser.START_TAG) {
                if (parser.getName().equals("username")) {
                    registration.setUsername(parser.nextText());
                }
                else if (parser.getName().equals("password")) {
                    registration.setPassword(parser.nextText());
                }
                // Else if any other element that's in the jabber:iq:register namespace,
                // attempt to parse it if it's in the form <name>value</name>.
                else if (parser.getNamespace().equals("jabber:iq:register")) {
                    String name = parser.getName();
                    String value = "";
                    if (fields == null) {
                        fields = new HashMap();
                    }

                    if (parser.next() == XmlPullParser.TEXT) {
                        value = parser.getText();
                    }
                    // Ignore instructions, but anything else should be added to the map.
                    if (!name.equals("instructions")) {
                        fields.put(name, value);
                    }
                    else {
                        registration.setInstructions(value);
                    }
}
                // Otherwise, it must be a packet extension.
                else {
                    registration.addExtension(
                        PacketParserUtils.parsePacketExtension(
                            parser.getName(),
                            parser.getNamespace(),
                            parser));
                }
            }
            else if (eventType == XmlPullParser.END_TAG) {
                if (parser.getName().equals("query")) {
                    done = true;
                }
            }
        }
        registration.setAttributes(fields);
        return registration;
    }

    /**
     * A wrapper class to associate a packet collector with a listener.
     */
    private static class ListenerWrapper {

        private PacketListener packetListener;
        private PacketCollector packetCollector;

        public ListenerWrapper(PacketReader packetReader, PacketListener packetListener,
                PacketFilter packetFilter)
        {
            this.packetListener = packetListener;
            this.packetCollector = new PacketCollector(packetReader, packetFilter);
        }

        public boolean equals(Object object) {
            if (object == null) {
                return false;
            }
            if (object instanceof ListenerWrapper) {
                return ((ListenerWrapper)object).packetListener.equals(this.packetListener);
            }
            else if (object instanceof PacketListener) {
                return object.equals(this.packetListener);
            }
            return false;
        }

        public boolean notifyListener() {
            Packet packet = packetCollector.pollResult();
            if (packet != null) {
                packetListener.processPacket(packet);
                return true;
            }
            else {
                return false;
            }
        }

        public void cancel() {
            packetCollector.cancel();
            packetCollector = null;
            packetListener = null;
        }
    }
}