// ========================================================================
   // Copyright (c) 2004-2009 Mort Bay Consulting Pty. Ltd.
   // ------------------------------------------------------------------------
   // All rights reserved. This program and the accompanying materials
   // are made available under the terms of the Eclipse Public License v1.0
   // and Apache License v2.0 which accompanies this distribution.
   // The Eclipse Public License is available at 
   // http://www.eclipse.org/legal/epl-v10.html
   // The Apache License v2.0 is available at
  // http://www.opensource.org/licenses/apache2.0.php
  // You may elect to redistribute this code under either of these licenses. 
  // ========================================================================
  
  package org.eclipse.jetty.webapp;
  
  import java.io.IOException;
  import java.net.URL;
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.EventListener;
  import java.util.HashSet;
  import java.util.Iterator;
  import java.util.List;
  import java.util.Set;
  
  import javax.servlet.Servlet;
  import javax.servlet.ServletContextEvent;
  import javax.servlet.ServletContextListener;
  
  import org.eclipse.jetty.util.Loader;
  import org.eclipse.jetty.util.log.Log;
  import org.eclipse.jetty.util.log.Logger;
  import org.eclipse.jetty.util.resource.Resource;
  import org.eclipse.jetty.xml.XmlParser;
  
  /* ------------------------------------------------------------ */
  /** TagLibConfiguration.
   * 
   * The class searches for TLD descriptors found in web.xml, in WEB-INF/*.tld files of the web app
   * or *.tld files within jars found in WEB-INF/lib of the webapp.   Any listeners defined in these
   * tld's are added to the context.
   * 
   * <bile>This is total rubbish special case for JSPs! If there was a general use-case for web app
   * frameworks to register listeners directly, then a generic mechanism could have been added to the servlet
   * spec.  Instead some special purpose JSP support is required that breaks all sorts of encapsulation rules as
   * the servlet container must go searching for and then parsing the descriptors for one particular framework.
   * It only appears to be used by JSF, which is being developed by the same developer who implemented this
   * feature in the first place!
   * </bile>
   * 
   * 
   * Note- this has been superceded by the new TldScanner in jasper which uses ServletContainerInitializer to
   * find all the listeners in tag libs and register them.
   */
  public class TagLibConfiguration extends AbstractConfiguration
  {
      private static final Logger LOG = Log.getLogger(TagLibConfiguration.class);
  
      public static final String TLD_RESOURCES = "org.eclipse.jetty.tlds";
      
      /**
       * TagLibListener
       *
       * A listener that does the job of finding .tld files that contain
       * (other) listeners that need to be called by the servlet container.
       * 
       * This implementation is necessitated by the fact that it is only
       * after all the Configuration classes have run that we will
       * parse web.xml/fragments etc and thus find tlds mentioned therein.
       * 
       * Note: TagLibConfiguration is not used in jetty-8 as jasper (JSP engine)
       * uses the new TldScanner class - a ServletContainerInitializer from
       * Servlet Spec 3 - to find all listeners in taglibs and register them
       * with the servlet container.
       */
      public  class TagLibListener implements ServletContextListener {
          private List<EventListener> _tldListeners;
          private WebAppContext _context;       
          
          public TagLibListener (WebAppContext context) {
              _context = context;
          }
  
          public void contextDestroyed(ServletContextEvent sce)
          {
              if (_tldListeners == null)
                  return;
              
              for (int i=_tldListeners.size()-1; i>=0; i--) {
                  EventListener l = _tldListeners.get(i);
                  if (l instanceof ServletContextListener) {
                      ((ServletContextListener)l).contextDestroyed(sce);
                  }
              }
          }
  
          public void contextInitialized(ServletContextEvent sce)
          {
              try {
                 //find the tld files and parse them to get out their
                 //listeners
                 Set<Resource> tlds = findTldResources();
                 List<TldDescriptor> descriptors = parseTlds(tlds);
                 processTlds(descriptors);
                 
                 if (_tldListeners == null)
                     return;
                 
                 //call the listeners that are ServletContextListeners, put the
                 //rest into the context's list of listeners to call at the appropriate
                 //moment
                 for (EventListener l:_tldListeners) {
                     if (l instanceof ServletContextListener) {
                         ((ServletContextListener)l).contextInitialized(sce);
                     } else {
                         _context.addEventListener(l);
                     }
                 }
                 
             } catch (Exception e) {
                 LOG.warn(e);
             }
         }
 
         
         /**
          * Find all the locations that can harbour tld files that may contain
          * a listener which the web container is supposed to instantiate and
          * call.
          * 
          * @return
          * @throws IOException
          */
         private Set<Resource> findTldResources () throws IOException {
             
             Set<Resource> tlds = new HashSet<Resource>();
             
             // Find tld's from web.xml
             // When web.xml was processed, it should have created aliases for all TLDs.  So search resources aliases
             // for aliases ending in tld
             if (_context.getResourceAliases()!=null && 
                     _context.getBaseResource()!=null && 
                     _context.getBaseResource().exists())
             {
                 Iterator<String> iter=_context.getResourceAliases().values().iterator();
                 while(iter.hasNext())
                 {
                     String location = iter.next();
                     if (location!=null && location.toLowerCase().endsWith(".tld"))
                     {
                         if (!location.startsWith("/"))
                             location="/WEB-INF/"+location;
                         Resource l=_context.getBaseResource().addPath(location);
                         tlds.add(l);
                     }
                 }
             }
             
             // Look for any tlds in WEB-INF directly.
             Resource web_inf = _context.getWebInf();
             if (web_inf!=null)
             {
                 String[] contents = web_inf.list();
                 for (int i=0;contents!=null && i<contents.length;i++)
                 {
                     if (contents[i]!=null && contents[i].toLowerCase().endsWith(".tld"))
                     {
                         Resource l=web_inf.addPath(contents[i]);
                         tlds.add(l);
                     }
                 }
             }
             
             //Look for tlds in common location of WEB-INF/tlds
             if (web_inf != null) {
                 Resource web_inf_tlds = _context.getWebInf().addPath("/tlds/");
                 if (web_inf_tlds.exists() && web_inf_tlds.isDirectory()) {
                     String[] contents = web_inf_tlds.list();
                     for (int i=0;contents!=null && i<contents.length;i++)
                     {
                         if (contents[i]!=null && contents[i].toLowerCase().endsWith(".tld"))
                         {
                             Resource l=web_inf_tlds.addPath(contents[i]);
                             tlds.add(l);
                         }
                     }
                 } 
             }
 
             // Add in tlds found in META-INF of jars. The jars that will be scanned are controlled by
             // the patterns defined in the context attributes: org.eclipse.jetty.server.webapp.ContainerIncludeJarPattern,
             // and org.eclipse.jetty.server.webapp.WebInfIncludeJarPattern
             @SuppressWarnings("unchecked")
             Collection<Resource> tld_resources=(Collection<Resource>)_context.getAttribute(TLD_RESOURCES);
             if (tld_resources!=null)
                 tlds.addAll(tld_resources);
             
             return tlds;
         }
         
         
         /**
          * Parse xml into in-memory tree
          * @param tlds
          * @return
          */
         private List<TldDescriptor> parseTlds (Set<Resource> tlds) {         
             List<TldDescriptor> descriptors = new ArrayList<TldDescriptor>();
             
             Resource tld = null;
             Iterator<Resource> iter = tlds.iterator();
             while (iter.hasNext())
             {
                 try
                 {
                     tld = iter.next();
                     if (LOG.isDebugEnabled()) LOG.debug("TLD="+tld);
                    
                     TldDescriptor d = new TldDescriptor(tld);
                     d.parse();
                     descriptors.add(d);
                 }
                 catch(Exception e)
                 {
                     LOG.warn("Unable to parse TLD: " + tld,e);
                 }
             }
             return descriptors;
         }
         
         
         /**
          * Create listeners from the parsed tld trees
          * @param descriptors
          * @throws Exception
          */
         private void processTlds (List<TldDescriptor> descriptors) throws Exception {
 
             TldProcessor processor = new TldProcessor();
             for (TldDescriptor d:descriptors)
                 processor.process(_context, d); 
             
             _tldListeners = new ArrayList<EventListener>(processor.getListeners());
         }
     }
     
     
     
     
     /**
      * TldDescriptor
      *
      *
      */
     public static class TldDescriptor extends Descriptor
     {
         protected static XmlParser __parserSingleton;
 
         public TldDescriptor(Resource xml)
         {
             super(xml);
         }
 
         @Override
         public void ensureParser() throws ClassNotFoundException
         {
            if (__parserSingleton == null)
                __parserSingleton = newParser();
             _parser = __parserSingleton;
         }
 
         @Override
         public XmlParser newParser() throws ClassNotFoundException
         {
             // Create a TLD parser
             XmlParser parser = new XmlParser(false);
             
             URL taglib11=null;
             URL taglib12=null;
             URL taglib20=null;
             URL taglib21=null;
 
             try
             {
                 Class<?> jsp_page = Loader.loadClass(WebXmlConfiguration.class,"javax.servlet.jsp.JspPage");
                 taglib11=jsp_page.getResource("javax/servlet/jsp/resources/web-jsptaglibrary_1_1.dtd");
                 taglib12=jsp_page.getResource("javax/servlet/jsp/resources/web-jsptaglibrary_1_2.dtd");
                 taglib20=jsp_page.getResource("javax/servlet/jsp/resources/web-jsptaglibrary_2_0.xsd");
                 taglib21=jsp_page.getResource("javax/servlet/jsp/resources/web-jsptaglibrary_2_1.xsd");
             }
             catch(Exception e)
             {
                 LOG.ignore(e);
             }
             finally
             {
                 if(taglib11==null)
                     taglib11=Loader.getResource(Servlet.class,"javax/servlet/jsp/resources/web-jsptaglibrary_1_1.dtd",true);
                 if(taglib12==null)
                     taglib12=Loader.getResource(Servlet.class,"javax/servlet/jsp/resources/web-jsptaglibrary_1_2.dtd",true);
                 if(taglib20==null)
                     taglib20=Loader.getResource(Servlet.class,"javax/servlet/jsp/resources/web-jsptaglibrary_2_0.xsd",true);
                 if(taglib21==null)
                     taglib21=Loader.getResource(Servlet.class,"javax/servlet/jsp/resources/web-jsptaglibrary_2_1.xsd",true);
             }
             
 
             if(taglib11!=null)
             {
                 redirect(parser, "web-jsptaglib_1_1.dtd",taglib11);  
                 redirect(parser, "web-jsptaglibrary_1_1.dtd",taglib11);
             }
             if(taglib12!=null)
             {
                 redirect(parser, "web-jsptaglib_1_2.dtd",taglib12);
                 redirect(parser, "web-jsptaglibrary_1_2.dtd",taglib12);
             }
             if(taglib20!=null)
             {
                 redirect(parser, "web-jsptaglib_2_0.xsd",taglib20);
                 redirect(parser, "web-jsptaglibrary_2_0.xsd",taglib20);
             }
             if(taglib21!=null)
             {
                 redirect(parser, "web-jsptaglib_2_1.xsd",taglib21);
                 redirect(parser, "web-jsptaglibrary_2_1.xsd",taglib21);
             }
             
             parser.setXpath("/taglib/listener/listener-class");
             return parser;
         }
         
         public void parse ()
         throws Exception
         {
             ensureParser();
             try
             {
                 //xerces on apple appears to sometimes close the zip file instead
                 //of the inputstream, so try opening the input stream, but if
                 //that doesn't work, fallback to opening a new url
                 _root = _parser.parse(_xml.getInputStream());
             }
             catch (Exception e)
             {
                 _root = _parser.parse(_xml.getURL().toString());
             }
 
             if (_root==null)
             {
                 LOG.warn("No TLD root in {}",_xml);
             }
         }
     }
     
     
     /**
      * TldProcessor
      *
      * Process TldDescriptors representing tag libs to find listeners.
      */
     public class TldProcessor extends IterativeDescriptorProcessor
     {
         public static final String TAGLIB_PROCESSOR = "org.eclipse.jetty.tagLibProcessor";
         XmlParser _parser;
         List<XmlParser.Node> _roots = new ArrayList<XmlParser.Node>();
         List<EventListener> _listeners;
         
         
         public TldProcessor ()
         throws Exception
         {  
             _listeners = new ArrayList<EventListener>();
             registerVisitor("listener", this.getClass().getDeclaredMethod("visitListener", __signature));
         }
       
 
         public void visitListener (WebAppContext context, Descriptor descriptor, XmlParser.Node node)
         {     
             String className=node.getString("listener-class",false,true);
             if (LOG.isDebugEnabled()) LOG.debug("listener="+className);
 
             try
             {
                 Class<?> listenerClass = context.loadClass(className);
                 EventListener l = (EventListener)listenerClass.newInstance();
                 _listeners.add(l);
             }
             catch(Exception e)
             {
                 LOG.warn("Could not instantiate listener "+className+": "+e);
                 LOG.debug(e);
             }
             catch(Error e)
             {
                 LOG.warn("Could not instantiate listener "+className+": "+e);
                 LOG.debug(e);
             }
 
         }
 
         @Override
         public void end(WebAppContext context, Descriptor descriptor)
         {
         }
 
         @Override
         public void start(WebAppContext context, Descriptor descriptor)
         {  
         }
         
         public List<EventListener> getListeners() {
             return _listeners;
         }
     }
 
 
     @Override
     public void preConfigure(WebAppContext context) throws Exception
     {
         try
         {
             Class<?> jsp_page = Loader.loadClass(WebXmlConfiguration.class,"javax.servlet.jsp.JspPage");
         }
         catch (Exception e)
         {
             //no jsp available, don't parse TLDs
             return;
         }
 
         TagLibListener tagLibListener = new TagLibListener(context);
         context.addEventListener(tagLibListener);
     }
     
 
     @Override
     public void configure (WebAppContext context) throws Exception
     {         
     }
 
     @Override
     public void postConfigure(WebAppContext context) throws Exception
     {     
     }
 
 
     @Override
     public void cloneConfigure(WebAppContext template, WebAppContext context) throws Exception
     {
     }
 
 
     @Override
     public void deconfigure(WebAppContext context) throws Exception
     {
     } 
 }