// ========================================================================
   // Copyright (c) 2004-2011 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.osgi.boot.jsp;
  
  import java.io.IOException;
  import java.net.URL;
  import java.util.Collection;
  import java.util.Enumeration;
  import java.util.LinkedHashSet;
  
  import org.eclipse.jetty.osgi.boot.OSGiWebappConstants;
  import org.eclipse.jetty.osgi.boot.utils.internal.DefaultFileLocatorHelper;
  import org.eclipse.jetty.util.log.Log;
  import org.eclipse.jetty.util.resource.Resource;
  import org.eclipse.jetty.webapp.TagLibConfiguration;
  import org.eclipse.jetty.webapp.WebAppContext;
  import org.osgi.framework.Bundle;
  import org.osgi.framework.BundleReference;
  import org.osgi.service.packageadmin.PackageAdmin;
  import org.osgi.util.tracker.ServiceTracker;
  
  /**
   * <p>
   * Replacement for {@link TagLibConfiguration} for the OSGi integration.
   * </p>
   * <p>
   * In the case of a WAB, tlds can be located in OSGi bundles that are dependencies
   * of the WAB.
   * It is expected that each WAB lists the symbolic-names of the bundles that contain
   * tld files. The list is defined as the value of the header 'Require-TldBundle'
   * </p>
   * <p>
   * Discussions about this are logged in https://bugs.eclipse.org/bugs/show_bug.cgi?id=306971
   * </p>
   */
  public class TagLibOSGiConfiguration extends TagLibConfiguration
  {
  	private ServiceTracker packageAdminServiceTracker = null;
  	
  	/**
  	 * Override the preConfigure; locates the bundles that contain
  	 * tld files according to the value of the manifest header Require-TldBundle.
  	 * <p>
  	 * Set or add to the property TldProcessor.TLDResources the list of located jars
  	 * so that the super class will scan those.
  	 * </p>
  	 */
      public void preConfigure(WebAppContext context) throws Exception
      {
      	String requireTldBundle = (String)context.getAttribute(OSGiWebappConstants.REQUIRE_TLD_BUNDLE);
      	if (requireTldBundle != null)
      	{
      		Collection<Resource> resources = getRequireTldBundleAsJettyResources(context, requireTldBundle);
      		if (resources != null && !resources.isEmpty())
      		{
      			Collection<Resource> previouslySet = (Collection<Resource>)
      				context.getAttribute(TagLibConfiguration.TLD_RESOURCES);
      			if (previouslySet != null)
      			{
      				resources.addAll(previouslySet);
      			}
      			context.setAttribute(TagLibConfiguration.TLD_RESOURCES, resources);
      		}
      	}
      	super.preConfigure(context);
  
      }
  
      /**
       * @param requireTldBundle The comma separated list of bundles' symbolic names
       * that contain tld for this osgi webapp.
       * @return The collection of jars or folders that match those bundles.
       */
      private Collection<Resource> getRequireTldBundleAsJettyResources(
      		WebAppContext context, String requireTldBundle)
      {
      	Bundle bundle = (Bundle)
      		context.getAttribute(OSGiWebappConstants.JETTY_OSGI_BUNDLE);
      	PackageAdmin packAdmin = getBundleAdmin();
      	String[] symbNames = requireTldBundle.split(", ");
      	Collection<Resource> tlds = new LinkedHashSet<Resource>();
      	for (String symbName : symbNames)
      	{
      		Bundle[] bs = packAdmin.getBundles(symbName, null);
      		if (bs == null || bs.length == 0)
      		{
      			throw new IllegalArgumentException("Unable to locate the bundle '"
      					+ symbName + "' specified in the "
      					+ OSGiWebappConstants.REQUIRE_TLD_BUNDLE
     					+ " of the manifest of "
     					+ bundle.getSymbolicName());
     		}
     		//take the first one as it is the most recent version?
 			Enumeration<URL> en = bs[0].findEntries("META-INF", "*.tld", false);
 			boolean atLeastOneTldFound = false;
 			while (en.hasMoreElements())
 			{
 				atLeastOneTldFound = true;
 				URL oriUrl = en.nextElement();
 				URL url = DefaultFileLocatorHelper.getLocalURL(oriUrl);
 				Resource tldResource;
 				try
 				{
 					tldResource = Resource.newResource(url);
 				}
 				catch (IOException e)
 				{
 					throw new IllegalArgumentException("Unable to locate the "
 							+ "tld resource in '"
 	    					+ url.toString()
 	    					+ "' in the bundle '" + bs[0].getSymbolicName()
 	    					+ "' while registering the "
 	    					+ OSGiWebappConstants.REQUIRE_TLD_BUNDLE
 	    					+ " of the manifest of "
 	    					+ bundle.getSymbolicName(), e);
 				}
 				tlds.add(tldResource);
 			}
 			if (!atLeastOneTldFound)
 			{
 				Log.warn("No '/META-INF/*.tld' resources were found "
     					+ " in the bundle '" + bs[0].getSymbolicName()
     					+ "' while registering the "
     					+ OSGiWebappConstants.REQUIRE_TLD_BUNDLE
     					+ " of the manifest of "
     					+ bundle.getSymbolicName());
 			}
     	}
     	return tlds;
     }
     
 	private PackageAdmin getBundleAdmin()
 	{
 		if (packageAdminServiceTracker == null)
 		{
 			Bundle bootBundle = ((BundleReference)OSGiWebappConstants.class.getClassLoader()).getBundle();
 			packageAdminServiceTracker = new ServiceTracker(bootBundle.getBundleContext(),
 					PackageAdmin.class.getName(), null);
 			packageAdminServiceTracker.open();
 		}
 		return (PackageAdmin) packageAdminServiceTracker.getService();
 	}
 	    
 }