/*
 * Copyright (c) JForum Team
 * All rights reserved.
 * 
 * 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) Neither the name of "Rafael Steil" nor 
 * the names of its contributors may be used to endorse 
 * or promote products derived from this software without 
 * specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT 
 * HOLDERS AND CONTRIBUTORS "AS IS" AND ANY 
 * EXPRESS 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 
 * THE COPYRIGHT OWNER OR 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
 * 
 * Created on 24/09/2006 23:04:29
 * The JForum Project
 * http://www.jforum.net
 */
package net.jforum.api.integration.mail.pop;

import java.util.Random;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import net.jforum.entities.Topic;

/**
 * Represents the In-Reply-To and Message-ID mail header.
 * 
 * @author Rafael Steil
 * @version $Id: MessageId.java,v 1.4 2006/10/09 03:05:54 rafaelsteil Exp $
 */
public class MessageId
{
	private static final Random random = new Random(System.currentTimeMillis());
	private int topicId;
	
	/**
	 * Returns the topic id this header holds.
	 * 
	 * @return the topic id represented by this instance
	 */
	public int getTopicId()
	{
		return this.topicId;
	}
	
	/**
	 * Constructs the Message-ID header.
	 * The form is "<postId.topicId.forumId.randomNumber@jforum>".
	 * 
	 * @param postId the post id of this message
	 * @param topicId the topic id of this message
	 * @param forumId the forum id of this message
	 * @return the Message-ID header
	 */
	public static String buildMessageId(int postId, int topicId, int forumId)
	{
		return new StringBuffer()
			.append('<')
			.append(postId)
			.append('.')
			.append(topicId)
			.append('.')
			.append(forumId)
			.append('.')
			.append(System.currentTimeMillis())
			.append(random.nextInt(999999999))
			.append("@jforum>")
			.toString();
	}

	/**
	 * Constructs the In-Reply-To header.
	 * The form is "<topicFirstPostId.topicId.forumId.randomNumber@jforum>".
	 *  
	 * @param topic The topic we're replying to. If should have at least the
	 * values for {@link Topic#getFirstPostId()}, {@link Topic#getId()}
	 * and {@link Topic#getForumId()}
	 * 
	 * @return the In-Reply-To header
	 */
	public static String buildInReplyTo(Topic topic)
	{
		return buildMessageId(topic.getFirstPostId(), topic.getId(), topic.getForumId());
	}
	
	/**
	 * Parses the header, extracting the information it holds
	 * @param header the header's contents to parse
	 * @return the header information parsed
	 */
	public static MessageId parse(String header)
	{
		MessageId messageId = new MessageId();
		
		if (header != null) {
			// <postId.topicId.forumId.randomNumber@host>
			Matcher matcher = Pattern.compile("<(.*?)\\.(.*?)\\.(.*?)\\.(.*?)@.*>").matcher(header);
			
			if (matcher.matches()) {
				String s = matcher.group(2);
				
				try {
					messageId.topicId = Integer.parseInt(s);
				}
				catch (Exception e) { }
			}
		}
		
		return messageId;
	}
}