// ========================================================================
   // Copyright (c) 2009 Intalio, Inc.
   // ------------------------------------------------------------------------
   // 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.utils.internal;
  
  import java.util.ArrayList;
  import java.util.LinkedHashMap;
  import java.util.List;
  import java.util.Map;
  import java.util.StringTokenizer;
  
  import org.osgi.framework.Bundle;
  import org.osgi.framework.BundleActivator;
  import org.osgi.framework.BundleContext;
  import org.osgi.framework.InvalidSyntaxException;
  import org.osgi.framework.ServiceEvent;
  import org.osgi.framework.ServiceListener;
  import org.osgi.framework.ServiceReference;
  import org.osgi.service.packageadmin.PackageAdmin;
  import org.osgi.service.startlevel.StartLevel;
  
  /**
   * When the PackageAdmin service is activated we can look for the fragments
   * attached to this bundle and "activate" them.
   */
  public class PackageAdminServiceTracker implements ServiceListener
  {
      private BundleContext _context;
  
      private List<BundleActivator> _activatedFragments = new ArrayList<BundleActivator>();
  
      private boolean _fragmentsWereActivated = false;
  
      // Use the deprecated StartLevel to stay compatible with older versions of
      // OSGi.
      private StartLevel _startLevel;
  
      private int _maxStartLevel = 6;
  
      public static PackageAdminServiceTracker INSTANCE = null;
  
      public PackageAdminServiceTracker(BundleContext context)
      {
          INSTANCE = this;
          _context = context;
          if (!setup())
          {
              try
              {
                  _context.addServiceListener(this, "(objectclass=" + PackageAdmin.class.getName() + ")");
              }
              catch (InvalidSyntaxException e)
              {
                  e.printStackTrace(); // won't happen
              }
          }
      }
  
      /**
       * @return true if the fragments were activated by this method.
       */
      private boolean setup()
      {
          ServiceReference sr = _context.getServiceReference(PackageAdmin.class.getName());
          _fragmentsWereActivated = sr != null;
          if (sr != null) invokeFragmentActivators(sr);
  
          sr = _context.getServiceReference(StartLevel.class.getName());
          if (sr != null)
          {
              _startLevel = (StartLevel) _context.getService(sr);
              try
              {
                  _maxStartLevel = Integer.parseInt(System.getProperty("osgi.startLevel", "6"));
              }
              catch (Exception e)
              {
                  // nevermind default on the usual.
                  _maxStartLevel = 6;
              }
          }
          return _fragmentsWereActivated;
      }
  
      /**
       * Invokes the optional BundleActivator in each fragment. By convention the
       * bundle activator for a fragment must be in the package that is defined by
       * the symbolic name of the fragment and the name of the class must be
       * 'FragmentActivator'.
       * 
      * @param event The <code>ServiceEvent</code> object.
      */
     public void serviceChanged(ServiceEvent event)
     {
         if (event.getType() == ServiceEvent.REGISTERED)
         {
             invokeFragmentActivators(event.getServiceReference());
         }
     }
 
     /**
      * Helper to access the PackageAdmin and return the fragments hosted by a
      * bundle. when we drop the support for the older versions of OSGi, we will
      * stop using the PackageAdmin service.
      * 
      * @param bundle
      * @return
      */
     public Bundle[] getFragments(Bundle bundle)
     {
         ServiceReference sr = _context.getServiceReference(PackageAdmin.class.getName());
         if (sr == null)
         {// we should never be here really.
             return null;
         }
         PackageAdmin admin = (PackageAdmin) _context.getService(sr);
         return admin.getFragments(bundle);
     }
 
     /**
      * Returns the fragments and the required-bundles of a bundle. Recursively
      * collect the required-bundles and fragment when the directive
      * visibility:=reexport is added to a required-bundle.
      * 
      * @param bundle
      * @param webFragOrAnnotationOrResources
      * @return
      */
     public Bundle[] getFragmentsAndRequiredBundles(Bundle bundle)
     {
         ServiceReference sr = _context.getServiceReference(PackageAdmin.class.getName());
         if (sr == null)
         {// we should never be here really.
             return null;
         }
         PackageAdmin admin = (PackageAdmin) _context.getService(sr);
         LinkedHashMap<String, Bundle> deps = new LinkedHashMap<String, Bundle>();
         collectFragmentsAndRequiredBundles(bundle, admin, deps, false);
         return deps.values().toArray(new Bundle[deps.size()]);
     }
 
     /**
      * Returns the fragments and the required-bundles. Collects them
      * transitively when the directive 'visibility:=reexport' is added to a
      * required-bundle.
      * 
      * @param bundle
      * @param webFragOrAnnotationOrResources
      * @return
      */
     protected void collectFragmentsAndRequiredBundles(Bundle bundle, PackageAdmin admin, Map<String, Bundle> deps, boolean onlyReexport)
     {
         Bundle[] fragments = admin.getFragments(bundle);
         if (fragments != null)
         {
             // Also add the bundles required by the fragments.
             // this way we can inject onto an existing web-bundle a set of
             // bundles that extend it
             for (Bundle f : fragments)
             {
                 if (!deps.keySet().contains(f.getSymbolicName()))
                 {
                     deps.put(f.getSymbolicName(), f);
                     collectRequiredBundles(f, admin, deps, onlyReexport);
                 }
             }
         }
         collectRequiredBundles(bundle, admin, deps, onlyReexport);
     }
 
     /**
      * A simplistic but good enough parser for the Require-Bundle header. Parses
      * the version range attribute and the visibility directive.
      * 
      * @param onlyReexport true to collect resources and web-fragments
      *            transitively if and only if the directive visibility is
      *            reexport.
      * @param bundle
      * @return The map of required bundles associated to the value of the
      *         jetty-web attribute.
      */
     protected void collectRequiredBundles(Bundle bundle, PackageAdmin admin, Map<String, Bundle> deps, boolean onlyReexport)
     {
         String requiredBundleHeader = (String) bundle.getHeaders().get("Require-Bundle");
         if (requiredBundleHeader == null) { return; }
         StringTokenizer tokenizer = new ManifestTokenizer(requiredBundleHeader);
         while (tokenizer.hasMoreTokens())
         {
             String tok = tokenizer.nextToken().trim();
             StringTokenizer tokenizer2 = new StringTokenizer(tok, ";");
             String symbolicName = tokenizer2.nextToken().trim();
             if (deps.keySet().contains(symbolicName))
             {
                 // was already added. 2 dependencies pointing at the same
                 // bundle.
                 continue;
             }
             String versionRange = null;
             boolean reexport = false;
             while (tokenizer2.hasMoreTokens())
             {
                 String next = tokenizer2.nextToken().trim();
                 if (next.startsWith("bundle-version="))
                 {
                     if (next.startsWith("bundle-version=\"") || next.startsWith("bundle-version='"))
                     {
                         versionRange = next.substring("bundle-version=\"".length(), next.length() - 1);
                     }
                     else
                     {
                         versionRange = next.substring("bundle-version=".length());
                     }
                 }
                 else if (next.equals("visibility:=reexport"))
                 {
                     reexport = true;
                 }
             }
             if (!reexport && onlyReexport) { return; }
             Bundle[] reqBundles = admin.getBundles(symbolicName, versionRange);
             if (reqBundles != null && reqBundles.length != 0)
             {
                 Bundle reqBundle = null;
                 for (Bundle b : reqBundles)
                 {
                     if (b.getState() == Bundle.ACTIVE || b.getState() == Bundle.STARTING)
                     {
                         reqBundle = b;
                         break;
                     }
                 }
                 if (reqBundle == null)
                 {
                     // strange? in OSGi with Require-Bundle,
                     // the dependent bundle is supposed to be active already
                     reqBundle = reqBundles[0];
                 }
                 deps.put(reqBundle.getSymbolicName(), reqBundle);
                 collectFragmentsAndRequiredBundles(reqBundle, admin, deps, true);
             }
         }
     }
 
     private void invokeFragmentActivators(ServiceReference sr)
     {
         PackageAdmin admin = (PackageAdmin) _context.getService(sr);
         Bundle[] fragments = admin.getFragments(_context.getBundle());
         if (fragments == null) { return; }
         for (Bundle frag : fragments)
         {
             // find a convention to look for a class inside the fragment.
             try
             {
                 String fragmentActivator = frag.getSymbolicName() + ".FragmentActivator";
                 Class<?> c = Class.forName(fragmentActivator);
                 if (c != null)
                 {
                     BundleActivator bActivator = (BundleActivator) c.newInstance();
                     bActivator.start(_context);
                     _activatedFragments.add(bActivator);
                 }
             }
             catch (NullPointerException e)
             {
                 // e.printStackTrace();
             }
             catch (InstantiationException e)
             {
                 // e.printStackTrace();
             }
             catch (IllegalAccessException e)
             {
                 // e.printStackTrace();
             }
             catch (ClassNotFoundException e)
             {
                 // e.printStackTrace();
             }
             catch (Exception e)
             {
                 e.printStackTrace();
             }
         }
     }
 
     public void stop()
     {
         INSTANCE = null;
         for (BundleActivator fragAct : _activatedFragments)
         {
             try
             {
                 fragAct.stop(_context);
             }
             catch (Exception e)
             {
                 e.printStackTrace();
             }
         }
     }
 
     /**
      * @return true if the framework has completed all the start levels.
      */
     public boolean frameworkHasCompletedAutostarts()
     {
         return _startLevel == null ? true : _startLevel.getStartLevel() >= _maxStartLevel;
     }
 
     private static class ManifestTokenizer extends StringTokenizer
     {
 
         public ManifestTokenizer(String header)
         {
             super(header, ",");
         }
 
         @Override
         public String nextToken()
         {
             String token = super.nextToken();
 
             while (hasOpenQuote(token) && hasMoreTokens())
             {
                 token += "," + super.nextToken();
             }
             return token;
         }
 
         private boolean hasOpenQuote(String token)
         {
             int i = -1;
             do
             {
                 int quote = getQuote(token, i + 1);
                 if (quote < 0) { return false; }
 
                 i = token.indexOf(quote, i + 1);
                 i = token.indexOf(quote, i + 1);
             }
             while (i >= 0);
             return true;
         }
 
         private int getQuote(String token, int offset)
         {
             int i = token.indexOf('"', offset);
             int j = token.indexOf('\'', offset);
             if (i < 0)
             {
                 if (j < 0)
                 {
                     return -1;
                 }
                 else
                 {
                     return '\'';
                 }
             }
             if (j < 0) { return '"'; }
             if (i < j) { return '"'; }
             return '\'';
         }
 
     }
 
 }