package chat;

import javax.servlet.http.HttpSessionAttributeListener;
import javax.servlet.http.HttpSessionBindingEvent;
import javax.servlet.http.HttpSession;
import javax.servlet.ServletContext;

/**
It is used by Chat Application for listening to session events.
* @author Sukhwinder Singh
*/
public class SessionListener implements HttpSessionAttributeListener 
{
	public void attributeAdded(HttpSessionBindingEvent hsbe)
	{
		//System.out.println("Attribute has been bound");
	}

	public void attributeReplaced(HttpSessionBindingEvent hsbe)
	{
		//System.out.println("Attribute has been replaced");
	}

	/** This is the method we are interested in. It deletes a user from this list of users when his session
		expires.
	*/
	public void attributeRemoved(HttpSessionBindingEvent hsbe)
	{
		String name = hsbe.getName();
		HttpSession session = hsbe.getSession();
		if ("nickname".equalsIgnoreCase(name)) {
			String nickname = (String)hsbe.getValue();
			if (nickname != null) {
				ServletContext application = session.getServletContext();
				if (application != null) {
					Object o = application.getAttribute("chatroomlist");		
					if (o != null) {
						ChatRoomList roomList = (ChatRoomList)o;
						ChatRoom[] rooms = roomList.getRoomListArray();
						for (int i = 0; i < rooms.length; i++) {
							if (rooms[i] != null) {
								Object chatter = rooms[i].removeChatter(nickname);
								if (chatter != null) {
									rooms[i].addMessage(new Message("system", ((Chatter)chatter).getName() + " has logged out.", new java.util.Date().getTime()));
								}
							}
						}
					}
				} else {
					System.out.println("ServletContext is null");
				}					
			}
		}		
	}
}