package fcexample.controller;

import javax.servlet.*;
import javax.servlet.http.*;
import java.io.IOException;

import fcexample.model.*;

/**
 * A simple implementation of a front controller servlet.  This servlet 
 * intercepts all requests to urls starting with "/pages."  After processing
 * it strips "/pages" off the given URL and forwards to that.
 */
public class FrontController extends HttpServlet {
    // parameters shared with login.jsp.  These must exactly match the 
    // property names in the JSP.
    public static final String USERNAME_PARAM = "username";
    public static final String PASSWORD_PARAM = "password";
    public static final String USERBEAN_ATTR = "userbean";
    public static final String CONTROLLER_PREFIX = "/pages";
    
    /**
     * Handle get requests by forwarding to a common processor
     */
    protected void doGet(HttpServletRequest request,
                         HttpServletResponse response)
        throws ServletException, IOException 
    {
        process(request, response);
    }
    
    /**
     * Handle post requests by forwarding to a common processor
     */
    protected void doPost(HttpServletRequest request,
                          HttpServletResponse response)
        throws ServletException, IOException 
    {
        process(request, response);
    }
    
    /**
     * The common processor method.  Check if this user is logged in or not.
     * If they are not, forward to the login page, otherwise forward to the
     * requested URL.
     */
    protected void process(HttpServletRequest request,
                           HttpServletResponse response)
        throws ServletException, IOException
    {
        // the default next page
        String nextPage = request.getPathInfo();
        
        // find userbean from session
        HttpSession session = request.getSession(true);
        UserBean userBean = (UserBean) session.getAttribute(USERBEAN_ATTR);
        
        if (userBean == null || !userBean.isLoggedIn()) {
            // read request parameters
            String username = request.getParameter(USERNAME_PARAM);
            String password = request.getParameter(PASSWORD_PARAM);
            
            // if the userbean doesn't exists, create it
            if (userBean == null) {
                userBean = UserBeanFactory.newInstance();
                session.setAttribute(USERBEAN_ATTR, userBean);
            }
            
            // record the username and password values
            userBean.setUsername(username);
            userBean.setPassword(password);
            
            // attempt to login
            boolean result = userBean.doLogin();
            
            // if we failed, redirect to the login page
            if (!result) {
                nextPage = "/login.jsp";
            }
        }
        
        // transfer control to the desired view
        RequestDispatcher dispatcher = 
            getServletContext().getRequestDispatcher(nextPage);
        dispatcher.forward(request, response);	
    }    
}