package com.atlassian.plugin.osgi.factory;
   
   import com.atlassian.plugin.IllegalPluginStateException;
   import com.atlassian.plugin.module.ContainerAccessor;
   import com.atlassian.plugin.osgi.container.OsgiContainerException;
   import com.atlassian.plugin.osgi.spring.DefaultSpringContainerAccessor;
   import com.atlassian.plugin.osgi.util.BundleClassLoaderAccessor;
   import com.atlassian.plugin.osgi.util.OsgiHeaderUtil;
   import com.atlassian.plugin.util.resource.AlternativeDirectoryResourceLoader;
  import com.google.common.base.Function;
  import org.apache.felix.framework.resolver.Module;
  import org.apache.felix.framework.resolver.Wire;
  import org.osgi.framework.Bundle;
  import org.osgi.service.packageadmin.PackageAdmin;
  import org.osgi.util.tracker.ServiceTracker;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import java.io.InputStream;
  import java.lang.reflect.InvocationTargetException;
  import java.lang.reflect.Method;
  import java.net.URL;
  import java.util.Dictionary;
  import java.util.HashSet;
  import java.util.List;
  import java.util.Set;
  
  import static com.atlassian.fugue.Option.option;
  import static com.atlassian.fugue.Suppliers.alwaysFalse;
  import static com.google.common.base.Preconditions.checkNotNull;
  
  /**
   * Helper class that implements the methods assuming the OSGi plugin has been installed
   *
   * @since 2.2.0
   */
  final class OsgiPluginInstalledHelper implements OsgiPluginHelper
  {
      private static final Logger logger = LoggerFactory.getLogger(OsgiPluginInstalledHelper.class);
      private final ClassLoader bundleClassLoader;
      private final Bundle bundle;
      private final PackageAdmin packageAdmin;
      private volatile ContainerAccessor containerAccessor;
      private volatile ServiceTracker[] serviceTrackers;
  
      /**
       * @param bundle The bundle
       * @param packageAdmin The package admin
       */
      public OsgiPluginInstalledHelper(final Bundle bundle, final PackageAdmin packageAdmin)
      {
          this.bundle = checkNotNull(bundle);
          this.packageAdmin = checkNotNull(packageAdmin);
          bundleClassLoader = BundleClassLoaderAccessor.getClassLoader(bundle, new AlternativeDirectoryResourceLoader());
      }
  
      public Bundle getBundle()
      {
          return bundle;
      }
  
      public <T> Class<T> loadClass(final String clazz, final Class<?> callingClass) throws ClassNotFoundException
      {
          return BundleClassLoaderAccessor.loadClass(getBundle(), clazz);
      }
  
      public URL getResource(final String name)
      {
          return bundleClassLoader.getResource(name);
      }
  
      public InputStream getResourceAsStream(final String name)
      {
          return bundleClassLoader.getResourceAsStream(name);
      }
  
      public ClassLoader getClassLoader()
      {
          return bundleClassLoader;
      }
  
      public Bundle install()
      {
          logger.debug("Not installing OSGi plugin '{}' since it's already installed.", bundle.getSymbolicName());
          throw new IllegalPluginStateException("Plugin '" + bundle.getSymbolicName() + "' has already been installed");
      }
  
      public void onEnable(final ServiceTracker... serviceTrackers) throws OsgiContainerException
      {
          for (final ServiceTracker svc : checkNotNull(serviceTrackers))
          {
              svc.open();
          }
  
          this.serviceTrackers = serviceTrackers;
      }
  
      public void onDisable() throws OsgiContainerException
      {
         final ServiceTracker[] serviceTrackers = this.serviceTrackers; // cache a copy locally for multi-threaded goodness
         if (serviceTrackers != null)
         {
             for (final ServiceTracker svc : serviceTrackers)
             {
                 svc.close();
             }
             this.serviceTrackers = null;
         }
         setPluginContainer(null);
     }
 
     public void onUninstall() throws OsgiContainerException
     {
     }
 
     public Set<String> getRequiredPlugins()
     {
         /* A bundle must move from INSTALLED to RESOLVED before we can get its import */
         if (bundle.getState() == Bundle.INSTALLED)
         {
             logger.debug("Bundle is in INSTALLED for {}", bundle.getSymbolicName());
             packageAdmin.resolveBundles(new Bundle[] { bundle });
             logger.debug("Bundle state is now {}", bundle.getState());
         }
 
         return getRequiredPluginKeys(bundle);
     }
 
     /**
      * This is taken from Felix itself and represents how it works out what other bundles are required by this
      * particular bundle.  It replaces a previous implementation that, while technically solid, was extremely slow and
      * showed up as a major method hot-spot in plugin reload times.
      * <p/>
      * While it uses reflection to gain access to "non public" methods, the speed trade-off makes it worthwhile
      */
     private Set<String> getRequiredPluginKeys(Bundle bundle)
     {
         String errMsg = null;
         Set<String> list = new HashSet<String>();
         try
         {
             //
             // future versions of Felix make this available, we do the needful for now
             // as the speed trade off is significant
             //
             Method getModules = bundle.getClass().getDeclaredMethod("getModules");
             getModules.setAccessible(true);
             //noinspection unchecked
             List<Module> modules = (List<Module>) getModules.invoke(bundle);
 
             for (Module module : modules)
             {
                 List<Wire> wires = module.getWires();
 
                 for (Wire wire : wires)
                 {
                     list.add(OsgiHeaderUtil.getPluginKey(wire.getExporter().getBundle()));
                 }
             }
         }
         catch (InvocationTargetException ignored)
         {
             errMsg = "Completely unexpected InvocationTargetException during Felix Bundle getModules().  Has the underlying Felix changed since this code was written?";
         }
         catch (NoSuchMethodException ignored)
         {
             errMsg = "Completely unexpected NoSuchMethodException during Felix Bundle getModules().  Has the underlying Felix changed since this code was written?";
         }
         catch (IllegalAccessException ignored)
         {
             errMsg = "Completely unexpected IllegalAccessException during Felix Bundle getModules().  Has the underlying Felix changed since this code was written?";
         }
         //
         // we know the code works with the version of Felix that was in play when this code was written
         // if this subsequently changes then we want to fail fast.  So we throw this exception to indicate this.
         if (errMsg != null)
         {
             throw new IllegalStateException(errMsg);
         }
 
         return list;
     }
 
     public void setPluginContainer(final Object container)
     {
         if (container == null)
         {
             containerAccessor = null;
         }
         else if (container instanceof ContainerAccessor)
         {
             containerAccessor = (ContainerAccessor) container;
         }
         else
         {
             containerAccessor = new DefaultSpringContainerAccessor(container);
         }
     }
 
     public ContainerAccessor getContainerAccessor()
     {
         return containerAccessor;
     }
 
     /**
      * @throws IllegalPluginStateException if the plugin container is not initialized
      */
     public ContainerAccessor getRequiredContainerAccessor() throws IllegalPluginStateException
     {
         if (containerAccessor == null)
         {
             throw new IllegalStateException("Cannot create object because the plugin container is unavailable.");
         }
         return containerAccessor;
     }
 
     @Override
     public boolean isRemotePlugin()
     {
         return option(getBundle().getHeaders()).fold(alwaysFalse(), new Function<Dictionary, Boolean>()
         {
             @Override
             public Boolean apply(Dictionary headers)
             {
                 return headers.get(OsgiPlugin.REMOTE_PLUGIN_KEY) != null;
             }
         });
     }
 }