/*

  * Licensed to the Apache Software Foundation (ASF) under one

  * or more contributor license agreements.  See the NOTICE file

  * distributed with this work for additional information

  * regarding copyright ownership.  The ASF licenses this file

  * to you under the Apache License, Version 2.0 (the

  * "License"); you may not use this file except in compliance

  * with the License.  You may obtain a copy of the License at

  *

  *   http://www.apache.org/licenses/LICENSE-2.0

  *

  * Unless required by applicable law or agreed to in writing,

  * software distributed under the License is distributed on an

  * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY

  * KIND, either express or implied.  See the License for the

  * specific language governing permissions and limitations

  * under the License.

  */

 package org.apache.myfaces.lifecycle;

 import javax.faces.context.FacesContext;

 import java.io.Serializable;

 import javax.servlet.http.Cookie;

 import javax.servlet.http.HttpServletResponse;

 import java.util.Map;

 /**

  * Contains information about whether the user has

  * JavaScript enabled on his client, etc.

  * It also contains the windowhandler html which gets sent to

  * the browser to detect the current windowId.

  *

  * This allows the 'customisation' of this html file to e.g.

  * adopt the background colour to avoid screen flickering.

  *

  * Please note that all subclasses of ClientConfig should also

  * be @SessionScoped as well!

  */

 public class ClientConfig implements Serializable

 {

     private static final long serialVersionUID = 581351549574404793L;

     /** We will set a cookie with this very name if a noscript link got clicked by the user */

     public static final String COOKIE_NAME_NOSCRIPT_ENABLED = "mfNoScriptEnabled";

     private volatile Boolean javaScriptEnabled = null;

     protected String windowHandlerHtml;

     /** lazily initiated via {@link #getUserAgent(javax.faces.context.FacesContext)} */

     private volatile String userAgent = null;

     /**

      * The location of the default windowhandler resource

      */

     //private static final String DEFAULT_WINDOW_HANDLER_HTML_FILE = "static/windowhandler.html";

     /**

      * Defaults to <code>true</code>.

      * @return if the user has JavaScript enabled

      */

     public boolean isJavaScriptEnabled()

     {

         if (javaScriptEnabled == null)

         {

             synchronized(this)

             {

                 // double lock checking idiom on volatile variable works since java5

                 if (javaScriptEnabled == null)

                 {

                     // no info means that it is default -> true

                     javaScriptEnabled = Boolean.TRUE;

                     FacesContext facesContext = FacesContext.getCurrentInstance();

                     if (facesContext != null)

                     {

                         Cookie cookie = (Cookie) facesContext.getExternalContext().

                                 getRequestCookieMap().get(COOKIE_NAME_NOSCRIPT_ENABLED);

                         if (cookie!= null)

                         {

                             javaScriptEnabled = Boolean.parseBoolean((String) cookie.getValue());

                         }

                     }

                 }

             }

         }

         return javaScriptEnabled;

     }

     /**

      * Set it to <code>false</code> if you don't like to use the

      * JavaScript based client side windowhandler. In this case

      * the request will be returned directly.

      * @param javaScriptEnabled

      */

     public void setJavaScriptEnabled(boolean javaScriptEnabled)

     {

         this.javaScriptEnabled = javaScriptEnabled;

         // and now also store this information inside a cookie!

         FacesContext facesContext = FacesContext.getCurrentInstance();

         if (facesContext != null)

         {

             Object r = facesContext.getExternalContext().getResponse();

             if (r instanceof HttpServletResponse)

             {

                 Cookie cookie = new Cookie(COOKIE_NAME_NOSCRIPT_ENABLED, "" + javaScriptEnabled);

                 cookie.setPath("/"); // for all the server

                 HttpServletResponse response = (HttpServletResponse) r;

                 response.addCookie(cookie);

             }

         }

     }

     /**

      * For branding the whole windowhandler page - e.g. not only change the

      * background color, add some images and empty menu structure

      * or the language of the message text - you can just copy the content of the

      * {@link #DEFAULT_WINDOW_HANDLER_HTML_FILE} and adopt it to your needs.

      *

      * The reason for this is to minimize visual side effects on browsers who do

      * not properly support html5 localstorage.

      *

      * @return the location of the <i>windowhandler.html</i> resource

      *         which should be sent to the users browser.

      */

     /*

     public String getWindowHandlerResourceLocation()

     {

         return DEFAULT_WINDOW_HANDLER_HTML_FILE;

     }*/

     /**

      * This might return different windowhandlers based on user settings like

      * his language, an affiliation, etc

      * @return a String containing the whole windowhandler.html file.

      * @throws IOException

      */

     /*

     public String getWindowHandlerHtml() throws IOException

     {

         if (FacesContext.getCurrentInstance().isProjectStage(ProjectStage.Development) 

                 && windowHandlerHtml != null)

         {

             // use cached windowHandlerHtml except in Development

             return windowHandlerHtml;

         }

         InputStream is = ClassUtils.getContextClassLoader().getResourceAsStream(

                 getWindowHandlerResourceLocation());

         StringBuffer sb = new StringBuffer();

         try

         {

             byte[] buf = new byte[16 * 1024];

             int bytesRead;

             while ((bytesRead = is.read(buf)) != -1)

             {

                 String sbuf = new String(buf, 0, bytesRead);

                 sb.append(sbuf);

             }

         }

         finally

         {

             is.close();

         }

         windowHandlerHtml = sb.toString();

         return windowHandlerHtml;

     }*/

     /**

      * This information will get stored as it cannot

      * change during the session anyway.

      * @return the UserAgent of the request.

      */

     public String getUserAgent(FacesContext facesContext)

     {

         if (userAgent == null)

         {

             synchronized (this)

             {

                 if (userAgent == null)

                 {

                     Map<String, String[]> requestHeaders =

                             facesContext.getExternalContext().getRequestHeaderValuesMap();

                     if (requestHeaders != null &&

                             requestHeaders.containsKey("User-Agent"))

                     {

                         String[] userAgents = requestHeaders.get("User-Agent");

                         userAgent = userAgents.length > 0 ? userAgents[0] : null;

                     }

                 }

             }

         }

         return userAgent;

     }

     /**

      * Users can overload this method to define in which scenarios a request should result

      * in an 'intercepted' page with proper windowId detection. This can e.g. contain

      * blacklisting some userAgents.

      * By default the following User-Agents will be served directly:

      * <ul>

      *     <li>.*bot.*</li>

      *     <li>.*Bot.*</li>

      *     <li>.*Slurp.*</li>

      *     <li>.*Crawler.*</li>

      * </ul>

      * @return <code>true</code> if the Request should get 'intercepted' and the intermediate

      *        windowhandler.html page should get rendered first. By returning <code>false</code>

      *        the requested page will get rendered intermediately.

      * @see #getUserAgent(javax.faces.context.FacesContext) for determining the UserAgent

      */

     public boolean isClientSideWindowHandlerRequest(FacesContext facesContext)

     {

         if (!isJavaScriptEnabled())

         {

             return false;

         }

         String userAgent = getUserAgent(facesContext);

         if (userAgent != null &&

             ( userAgent.indexOf("bot")     >= 0 || // Googlebot, etc

               userAgent.indexOf("Bot")     >= 0 || // BingBot, etc

               userAgent.indexOf("Slurp")   >= 0 || // Yahoo Slurp

               userAgent.indexOf("Crawler") >= 0    // various other Crawlers

             ) )

         {

             return false;

         }

         return true;

     }

 }