/*
 * Copyright (C) 2005-2008 Jive Software, 2017-2023 Ignite Realtime Foundation. 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;

import org.jivesoftware.openfire.container.BasicModule;
import org.jivesoftware.openfire.entitycaps.EntityCapabilitiesManager;
import org.jivesoftware.openfire.handler.PresenceSubscribeHandler;
import org.jivesoftware.openfire.handler.PresenceUpdateHandler;
import org.jivesoftware.openfire.interceptor.InterceptorManager;
import org.jivesoftware.openfire.interceptor.PacketRejectedException;
import org.jivesoftware.openfire.session.ClientSession;
import org.jivesoftware.openfire.session.Session;
import org.jivesoftware.util.JiveGlobals;
import org.jivesoftware.util.LocaleUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.xmpp.packet.*;

import java.util.Arrays;

/**
 * <p>Route presence packets throughout the server.</p>
 * <p>Routing is based on the recipient and sender addresses. The typical
 * packet will often be routed twice, once from the sender to some internal
 * server component for handling or processing, and then back to the router
 * to be delivered to it's final destination.</p>
 *
 * @author Iain Shigeoka
 */
public class PresenceRouter extends BasicModule {

    private static final Logger Log = LoggerFactory.getLogger(PresenceRouter.class);

    private RoutingTable routingTable;
    private PresenceUpdateHandler updateHandler;
    private PresenceSubscribeHandler subscribeHandler;
    private PresenceManager presenceManager;
    private SessionManager sessionManager;
    private EntityCapabilitiesManager entityCapsManager;
    private MulticastRouter multicastRouter;
    private String serverName;

    /**
     * Constructs a presence router.
     */
    public PresenceRouter() {
        super("XMPP Presence Router");
    }

    /**
     * Routes presence packets.
     *
     * @param packet the packet to route.
     * @throws NullPointerException if the packet is null.
     */
    public void route(Presence packet) {
        if (packet == null) {
            throw new NullPointerException();
        }
        ClientSession session = sessionManager.getSession(packet.getFrom());
        try {
            // Invoke the interceptors before we process the read packet
            InterceptorManager.getInstance().invokeInterceptors(packet, session, true, false);
            if (session == null || session.getStatus() != Session.Status.CONNECTED) {
                handle(packet);
            }
            else if (SessionPacketRouter.isInvalidStanzaSentPriorToResourceBinding(packet, session)) {
                Log.debug("Closing session that attempts to send stanza to an entity other than the server itself or the client's account, before completing resource binding. Session closed: {}", session);
                session.deliverRawText(new StreamError(StreamError.Condition.not_authorized).toXML());
                return;
            }
            else {
                packet.setTo(session.getAddress());
                packet.setFrom((JID)null);
                packet.setError(PacketError.Condition.not_authorized);
                session.process(packet);
            }
            // Invoke the interceptors after we have processed the read packet
            InterceptorManager.getInstance().invokeInterceptors(packet, session, true, true);
        }
        catch (PacketRejectedException e) {
            if (session != null) {
                // An interceptor rejected this packet so answer with an error.
                Presence reply = new Presence();
                reply.setID(packet.getID());
                reply.setTo(session.getAddress());
                reply.setFrom(packet.getTo());

                if (e.getRejectionError() != null) {
                    reply.setError(e.getRejectionError());
                } else {
                    reply.setError(PacketError.Condition.not_allowed);
                }
                session.process(reply);

                // Check if a message notifying the rejection should be sent
                if (e.getRejectionMessage() != null && !e.getRejectionMessage().trim().isEmpty()) {
                    // A message for the rejection will be sent to the sender of the rejected packet
                    Message notification = new Message();
                    notification.setTo(session.getAddress());
                    notification.setFrom(packet.getTo());
                    notification.setBody(e.getRejectionMessage());
                    session.process(notification);
                }
            }
        }
    }

    private void handle(Presence packet) {
        JID recipientJID = packet.getTo();
        JID senderJID = packet.getFrom();
        // Check if the packet was sent to the server hostname
        if (recipientJID != null && recipientJID.getNode() == null &&
                recipientJID.getResource() == null && serverName.equals(recipientJID.getDomain())) {
            if (packet.getElement().element("addresses") != null) {
                // Presence includes multicast processing instructions. Ask the multicastRouter
                // to route this packet
                multicastRouter.route(packet);
                return;
            }
        }
        try {
            // Presences sent between components are just routed to the component
            if (recipientJID != null && !XMPPServer.getInstance().isLocal(recipientJID) &&
                    !XMPPServer.getInstance().isLocal(senderJID)) {
                // Route the packet
                routingTable.routePacket(recipientJID, packet);
                return;
            }

            Presence.Type type = packet.getType();
            // Presence updates (null is 'available')
            if (type == null || Presence.Type.unavailable == type) {
                // check for local server target
                if (recipientJID == null || recipientJID.getDomain() == null ||
                        "".equals(recipientJID.getDomain()) || (recipientJID.getNode() == null &&
                        recipientJID.getResource() == null) &&
                        serverName.equals(recipientJID.getDomain())) {
                    entityCapsManager.process(packet);
                    updateHandler.process(packet);
                }
                else {
                    // Trigger events for presences of remote users
                    if (senderJID != null && !serverName.equals(senderJID.getDomain()) &&
                            !routingTable.hasComponentRoute(senderJID)) {
                        entityCapsManager.process(packet);
                    }
                    
                    // Check that sender session is still active (let unavailable presence go through)
                    Session session = sessionManager.getSession(packet.getFrom());
                    if (session != null && session.getStatus() == Session.Status.CLOSED && type == null) {
                        Log.warn("Rejected available presence: " + packet + " - " + session);
                        return;
                    }

                    // The user sent a directed presence to an entity
                    // Broadcast it to all connected resources
                    for (JID jid : routingTable.getRoutes(recipientJID, senderJID)) {
                        // Register the sent directed presence
                        updateHandler.directedPresenceSent(packet, jid, recipientJID.toString());
                        // Route the packet
                        routingTable.routePacket(jid, packet);
                    }
                }

            }
            else if (Presence.Type.subscribe == type // presence subscriptions
                    || Presence.Type.unsubscribe == type
                    || Presence.Type.subscribed == type
                    || Presence.Type.unsubscribed == type)
            {
                subscribeHandler.process(packet);
            }
            else if (Presence.Type.probe == type) {
                // Handle a presence probe sent by a remote server
                if (!XMPPServer.getInstance().isLocal(recipientJID)) {
                    routingTable.routePacket(recipientJID, packet);
                }
                else {
                    // Handle probe to a local user
                    presenceManager.handleProbe(packet);
                }
            }
            else {
                // It's an unknown or ERROR type, just deliver it because there's nothing
                // else to do with it
                routingTable.routePacket(recipientJID, packet);
            }

        }
        catch (Exception e) {
            Log.error(LocaleUtils.getLocalizedString("admin.error.routing"), e);
            Session session = sessionManager.getSession(packet.getFrom());
            if (session != null) {
                Log.debug( "Closing session of '{}': {}", packet.getFrom(), session );
                session.close();
            }
        }
    }

    @Override
    public void initialize(XMPPServer server) {
        super.initialize(server);
        serverName = server.getServerInfo().getXMPPDomain();
        routingTable = server.getRoutingTable();
        updateHandler = server.getPresenceUpdateHandler();
        subscribeHandler = server.getPresenceSubscribeHandler();
        presenceManager = server.getPresenceManager();
        multicastRouter = server.getMulticastRouter();
        sessionManager = server.getSessionManager();
        entityCapsManager = server.getEntityCapabilitiesManager();
    }

    /**
     * Notification message indicating that a packet has failed to be routed to the recipient.
     *
     * @param recipient address of the entity that failed to receive the packet.
     * @param packet    Presence packet that failed to be sent to the recipient.
     */
    public void routingFailed( JID recipient, Packet packet )
    {
        Log.debug( "Presence sent to unreachable address: " + packet.toXML() );

        final Presence presence = (Presence) packet;

        // For a presence stanza with no 'type' attribute or a 'type' attribute
        // of "unavailable", the server MUST silently ignore the stanza.
        // (...)
        // For a presence stanza of type "subscribed", "unsubscribe", or
        // "unsubscribed", the server MUST ignore the stanza.
        if ( presence.getType() == null || Arrays.asList( Presence.Type.unavailable, Presence.Type.subscribed, Presence.Type.unsubscribe, Presence.Type.unsubscribed ).contains( presence.getType() ) ) {
            Log.trace( "Not bouncing a presence stanza of type {}", presence.getType() );
            return;
        }

        // If the presence subscription request cannot be locally delivered or
        // remotely routed (e.g., because the request is malformed, the local
        // contact does not exist, the remote server does not exist, an attempt
        // to contact the remote server times out, or any other error is
        // determined or experienced by the user's server), then the user's
        // server MUST return an appropriate error stanza to the user.
        if ( presence.getType() == Presence.Type.subscribe ) {
            Log.trace( "Bouncing a presence stanza of type {}", presence.getType() );
            bounce( presence );
        }

        bounce( presence );
    }

    private void bounce(Presence presence) {
        // The bouncing behavior as implemented beyond this point was introduced as part
        // of OF-1852. This kill-switch allows it to be disabled again in case it
        // introduces unwanted side-effects.
        if ( !JiveGlobals.getBooleanProperty( "xmpp.presence.bounce", true ) ) {
            Log.trace( "Not bouncing a presence stanza, as bouncing is disabled by configuration." );
            return;
        }

        // Do nothing if the packet included an error. This intends to prevent scenarios
        // where a stanza that is bounced itself gets bounced, causing a loop.
        if (presence.getError() != null) {
            Log.trace( "Not bouncing a stanza that included an error (to prevent never-ending loops of bounces-of-bounces)." );
            return;
        }

        // Do nothing if the sender was the server itself
        if (presence.getFrom() == null || presence.getFrom().toString().equals( serverName )) {
            Log.trace( "Not bouncing a stanza that was sent by the server itself." );
            return;
        }
        try {
            Log.trace( "Bouncing a presence stanza: {}", presence);

            // Generate a rejection response to the sender
            final Presence errorResponse = presence.createCopy();
            errorResponse.setError(PacketError.Condition.service_unavailable);
            errorResponse.setFrom(presence.getTo());
            errorResponse.setTo(presence.getFrom());
            // Send the response
            route(errorResponse);
        }
        catch (Exception e) {
            Log.error("An exception occurred while trying to bounce a presence stanza.", e);
        }
    }
}