/*
 * Copyright (c) 1998 Purple Technology, Inc. All Rights Reserved.
 * 
 * This software is the confidential and proprietary information of
 * Purple Technology, Inc. ("Confidential Information").  You shall
 * not disclose such Confidential Information and shall use it only in
 * accordance with the terms of the license agreement you entered into
 * with Purple Technology.
 * 
 * PURPLE TECHNOLOGY MAKES NO REPRESENTATIONS OR WARRANTIES ABOUT THE
 * SUITABILITY OF THE SOFTWARE, EITHER EXPRESS OR IMPLIED, INCLUDING
 * BUT NOT LIMITED TO THE IMPLIED WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT. PURPLE
 * TECHNOLOGY SHALL NOT BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES SUFFERED
 * BY LICENSEE ARISING IN ANY WAY AS A RESULT OF USING, MODIFYING OR
 * DISTRIBUTING THIS SOFTWARE OR ITS DERIVATIVES.
 *
 * Contact: alexc@purpletech.com (Alex Chaffee)
 */
package com.purpletech.servlets;

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

/**
 * This servlet detects whether the client accepts cookies. It acts as
 * a gateway, eventually sending the user to one of two URLs. One URL
 * results when the user has accepted the cookie; another results
 * either if the user rejected the cookie, or if the user's browser
 * does not support cookies. The intention is to use the "no-cookie"
 * page as a message to the user saying "this site requires cookies --
 * pretty please accept my cookies or the site won't work right."
 *
 * <p>
 * The sequence of events is: <ul>
 * <li>User invokes servlet
 * <li>Servlet drops a cookie on the client
 * <li>Servlet sends a redirect, pointing the user back to itself, with a flag saying "this is the test phase"
 * <li>The test phase detects whether<ul>
 *  <li>The client accepted the cookie
 *  <li>The client rejected the cookie (or the browser doesn't support cookies)
 * </ul>
 * <li>Servlet sends another redirect to the destination page
 * </ul>
 *
 * <p>Use the <code>urlCookies</code> and <code>urlNoCookies</code>
 * init parameters to specify the destination pages for clients that
 * accept and rejct cookies, respectively.  </p>
 *
 * <p> (It would be nice if all implementations of Session Tracking
 * used a similar technique. As it is, some servlet engines seem to
 * just check whether the <b>browser</b> can <b>potentially</b>
 * support cookies, not whether a particular user has disabled cookies
 * for this session or site.)
 * </p>
 *
 * <p><a href="http://www.purpletech.com/code/src/com/purpletech/servlets/CookieDetector.java">Download the source</a></p>
 *  
 **/
public class CookieDetector extends HttpServlet {

    String probeName = "CookieDetector.probe";
    
    public void doGet(HttpServletRequest req, HttpServletResponse res)
	throws IOException, ServletException
    {
	log("doGet");
	Cookie cookie;
	int port = req.getServerPort();
	String self = req.getScheme() + "://" + req.getServerName() +
	    (port == 80 ? "" : ":"+port) + req.getServletPath();
	log("self = " + self);
	String phase = req.getParameter("phase");
	log("phase = " + phase);
	if (phase == null) {
	    cookie = new Cookie(probeName, req.getServletPath());
	    cookie.setComment("Will this get dropped?");
	    cookie.setMaxAge(-1);
	    //	    cookie.setPath(req.getServletPath());
	    res.addCookie(cookie);
	    res.sendRedirect( self + "?phase=check" );
	}
	else if (phase.equals("check")) {
	    Cookie[] cookies = req.getCookies();
	    boolean hasCookies = false;
	    if (cookies != null) {
		for (int i = 0; i < cookies.length; i++) {
		    log("cookie " + cookies[i].getName() + "=" + cookies[i].getValue());
		    if (cookies [i].getName ().equals (probeName)) {
			if (cookies[i].getValue().equals(req.getServletPath()))
			{
			    hasCookies = true;
			    break;
			}
		    }
		}
	    }
	    String where;
	    String message = "";
	    if (hasCookies) {
		where = getInitParameter("urlCookies");
		if (where == null || where.equals("")) {
		    where = null;
		    message = "Client allows cookies";
		}
	    }
	    else {
		where = getInitParameter("urlNoCookies");
		if (where == null || where.equals("")) {
		    where = null;
		    message = "Client does not allow cookies";
		}		
	    }
	    if (where == null) {
		res.setContentType("text/plain");
		res.getWriter().println(message);
	    }
	    else {
		res.sendRedirect(where);
	    }
	}
    }
}