/**
 * $RCSfile:  $
 * $Revision:  $
 * $Date:  $
 *
 * Copyright (C) 2006 Jive Software. All rights reserved.
 * This software is the proprietary information of Jive Software. Use is subject to license terms.
 */
package org.jivesoftware.smack;

import org.jivesoftware.smack.util.StringUtils;
import org.jivesoftware.smack.util.collections.ReferenceMap;
import org.jivesoftware.smack.packet.Message;
import org.jivesoftware.smack.packet.Packet;
import org.jivesoftware.smack.filter.*;

import java.util.*;
import java.util.concurrent.CopyOnWriteArraySet;

/**
 * The chat manager keeps track of references to all current chats. It will not hold any references
 * in memory on its own so it is neccesary to keep a reference to the chat object itself. To be
 * made aware of new chats, register a listener by calling {@link #addChatListener(ChatListener)}.
 *
 * @author Alexander Wenckus
 */
public class ChatManager {
    /**
     * Returns the next unique id. Each id made up of a short alphanumeric
     * prefix along with a unique numeric value.
     *
     * @return the next id.
     */
    private static synchronized String nextID() {
        return prefix + Long.toString(id++);
    }

    /**
     * A prefix helps to make sure that ID's are unique across mutliple instances.
     */
    private static String prefix = StringUtils.randomString(5);

    /**
     * Keeps track of the current increment, which is appended to the prefix to
     * forum a unique ID.
     */
    private static long id = 0;

    /**
     * Maps thread ID to chat.
     */
    private Map<String, Chat> threadChats = new ReferenceMap<String, Chat>(ReferenceMap.HARD,
            ReferenceMap.WEAK);

    /**
     * Maps jids to chats
     */
    private Map<String, Chat> jidChats = new ReferenceMap<String, Chat>(ReferenceMap.HARD,
            ReferenceMap.WEAK);

    private Set<ChatListener> chatListeners = new CopyOnWriteArraySet<ChatListener>();

    private XMPPConnection connection;

    ChatManager(XMPPConnection connection) {
        this.connection = connection;

        PacketFilter filter = new AndFilter(new PacketTypeFilter(Message.class),
                new PacketFilter() {

                    public boolean accept(Packet packet) {
                        if (!(packet instanceof Message)) {
                            return false;
                        }
                        Message.Type messageType = ((Message) packet).getType();
                        return messageType != Message.Type.groupchat &&
                                messageType != Message.Type.headline;
                    }
                });
        // Add a listener for all message packets so that we can deliver errant
        // messages to the best Chat instance available.
        connection.addPacketListener(new PacketListener() {
            public void processPacket(Packet packet) {
                Message message = (Message) packet;
                Chat chat;
                if (message.getThread() == null) {
                    chat = getUserChat(StringUtils.parseBareAddress(message.getFrom()));
                }
                else {
                    chat = getThreadChat(message.getThread());
                }

                if(chat == null) {
                    chat = createChat(message);
                }
                deliverMessage(chat, message);
            }
        }, filter);
    }

    /**
     * Creates a new chat and returns it.
     *
     * @param userJID the user this chat is with.
     * @param listener the listener which will listen for new messages from this chat.
     * @return the created chat.
     */
    public Chat createChat(String userJID, PacketListener listener) {
        String threadID = nextID();

        Chat chat = createChat(userJID, threadID, true);
        chat.addMessageListener(listener);

        return chat;
    }

    private Chat createChat(String userJID, String threadID, boolean createdLocally) {
        Chat chat = new Chat(this, userJID, threadID);
        threadChats.put(threadID, chat);
        jidChats.put(userJID, chat);

        for(ChatListener listener : chatListeners) {
            listener.chatCreated(chat, createdLocally);
        }

        return chat;
    }

    private Chat createChat(Message message) {
        String threadID = message.getThread();
        String userJID = message.getFrom();

        return createChat(userJID, threadID, false);
    }

    private Chat getUserChat(String userJID) {
        return jidChats.get(userJID);
    }

    private Chat getThreadChat(String thread) {
        return threadChats.get(thread);
    }

    /**
     * Register a new listener with the ChatManager to recieve events related to chats.
     *
     * @param listener the listener.
     */
    public void addChatListener(ChatListener listener) {
        chatListeners.add(listener);
    }

    /**
     * Removes a listener, it will no longer be notified of new events related to chats.
     *
     * @param listener the listener that is being removed
     */
    public void removeChatListener(ChatListener listener) {
        chatListeners.remove(listener);
    }

    /**
     * Returns an unmodifiable collection of all chat listeners currently registered with this
     * manager.
     *
     * @return an unmodifiable collection of all chat listeners currently registered with this
     * manager.
     */
    public Collection<ChatListener> getChatListeners() {
        return Collections.unmodifiableCollection(chatListeners);
    }

    private void deliverMessage(Chat chat, Message message) {
        // Here we will run any interceptors
        chat.deliver(message);
    }

    void sendMessage(Chat chat, Message message) {
        // Here we will run any interceptors
        connection.sendPacket(message);
    }

    PacketCollector createPacketCollector(Chat chat) {
        return connection.createPacketCollector(new AndFilter(new ThreadFilter(chat.getThreadID()), 
                new FromContainsFilter(chat.getParticipant())));
    }

}