/**
 * $RCSfile$
 * $Revision$
 * $Date$
 *
 * Copyright (C) 2002-2003 Jive Software. All rights reserved.
 * ====================================================================
 * The Jive Software License (based on Apache Software License, Version 1.1)
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by
 *        Jive Software (http://www.jivesoftware.com)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Smack" and "Jive Software" must not be used to
 *    endorse or promote products derived from this software without
 *    prior written permission. For written permission, please
 *    contact webmaster@coolservlets.com.
 *
 * 5. Products derived from this software may not be called "Smack",
 *    nor may "Smack" appear in their name, without prior written
 *    permission of Jive Software.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL JIVE SOFTWARE OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 */

package org.jivesoftware.smack;

import org.jivesoftware.smack.packet.Message;
import org.jivesoftware.smack.util.StringUtils;
import org.jivesoftware.smack.filter.ThreadFilter;

/**
 * A chat is a series of messages sent between two users. Each chat has
 * a unique ID, which is used to track which messages are part of the chat.
 *
 * @see XMPPConnection#createChat(String)
 * @author Matt Tucker
 */
public class Chat {

    /**
     * A prefix helps to make sure that ID's are unique across mutliple instances.
     */
    private static String prefix = StringUtils.randomString(3);

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

    /**
     * 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++);
    }

    private XMPPConnection connection;
    private String chatID;
    private String participant;
    private PacketCollector messageCollector;

    /**
     * Creates a new chat with the specified user.
     *
     * @param connection the connection the chat will use.
     * @param participant the user to chat with.
     */
    public Chat(XMPPConnection connection, String participant) {
        this.connection = connection;
        this.participant = participant;
        // Automatically assign the next chat ID.
        chatID = nextID();

        messageCollector = connection.createPacketCollector(new ThreadFilter(chatID));
    }

    /**
     * Creates a new chat with the specified user and chat ID (the XMPP "thread).
     *
     * @param connection the connection the chat will use.
     * @param participant the user to chat with.
     * @param chatID the chat ID to use.
     */
    public Chat(XMPPConnection connection, String participant, String chatID) {
        this.connection = connection;
        this.participant = participant;
        this.chatID = chatID;

        messageCollector = connection.createPacketCollector(new ThreadFilter(chatID));
    }

    /**
     * Returns the unique id of this chat, which corresponds to the
     * <tt>thread</tt> field of XMPP messages.
     *
     * @return the unique ID of this chat.
     */
    public String getChatID() {
        return chatID;
    }

    /**
     * Returns the name of the user the chat is with.
     *
     * @return the name of the user the chat is occuring with.
     */
    public String getParticipant() {
        return participant;
    }

    /**
     * Sends the specified text as a message to the other chat participant.
     * This is a convenience method for:
     *
     * <pre>
     *     Message message = chat.createMessage();
     *     message.setBody(messageText);
     *     chat.sendMessage(message);
     * </pre>
     *
     * @param text the text to send.
     * @throws XMPPException if sending the message fails.
     */
    public void sendMessage(String text) throws XMPPException {
        Message message = createMessage();
        message.setBody(text);
        connection.sendPacket(message);
    }

    /**
     * Creates a new Message to the chat participant. The message returned
     * will have its thread property set with this chat ID.
     *
     * @return a new message addressed to the chat participant and
     *      using the correct thread value.
     * @see #sendMessage(Message)
     */
    public Message createMessage() {
        Message message = new Message(participant, Message.CHAT);
        message.setThread(chatID);
        return message;
    }

    /**
     * Sends a message to the other chat participant. The thread property of
     * the message will automatically set to this chat ID in case the Message
     * was not created using the {@link #createMessage() createMessage} method.
     *
     * @param message
     * @throws XMPPException
     */
    public void sendMessage(Message message) throws XMPPException {
        // Force the chatID since the user elected to send the message
        // through this chat object.
        message.setThread(chatID);
        connection.sendPacket(message);
    }

    /**
     * Polls for and returns the next message, or <tt>null</tt> if there isn't
     * a message immediately available. This method provides significantly different
     * functionalty than the {@link #nextMessage()} method since it's non-blocking.
     * In other words, the method call will always return immediately, whereas the
     * nextMessage method will return only when a message is available (or after
     * a specific timeout).
     *
     * @return the next message if one is immediately available and
     *      <tt>null</tt> otherwise.
     */
    public Message pollMessage() {
        return (Message)messageCollector.pollResult();
    }

    /**
     * Returns the next available message in the chat. The method call will block
     * (not return) until a message is available.
     *
     * @return the next message.
     */
    public Message nextMessage() {
        return (Message)messageCollector.nextResult();
    }

    /**
     * Returns the next available message in the chat. The method call will block
     * (not return) until a packet is available or the <tt>timeout</tt> has elapased.
     * If the timeout elapses without a result, <tt>null</tt> will be returned.
     *
     * @param timeout the maximum amount of time to wait for the next message.
     * @return the next message, or <tt>null</tt> if the timeout elapses without a
     *      message becoming available.
     */
    public Message nextMessage(long timeout) {
        return (Message)messageCollector.nextResult(timeout);
    }
}