package com.atlassian.plugin.osgi.factory;
   
   import com.atlassian.plugin.AutowireCapablePlugin;
   import com.atlassian.plugin.IllegalPluginStateException;
   import com.atlassian.plugin.ModuleDescriptor;
   import com.atlassian.plugin.PluginArtifact;
   import com.atlassian.plugin.PluginArtifactBackedPlugin;
   import com.atlassian.plugin.PluginState;
   import com.atlassian.plugin.event.PluginEventListener;
  import com.atlassian.plugin.event.PluginEventManager;
  import com.atlassian.plugin.event.events.PluginContainerFailedEvent;
  import com.atlassian.plugin.event.events.PluginContainerRefreshedEvent;
  import com.atlassian.plugin.event.events.PluginFrameworkShutdownEvent;
  import com.atlassian.plugin.event.events.PluginFrameworkStartedEvent;
  import com.atlassian.plugin.event.events.PluginRefreshedEvent;
  import com.atlassian.plugin.impl.AbstractPlugin;
  import com.atlassian.plugin.module.ContainerAccessor;
  import com.atlassian.plugin.module.ContainerManagedPlugin;
  import com.atlassian.plugin.osgi.container.OsgiContainerException;
  import com.atlassian.plugin.osgi.container.OsgiContainerManager;
  import com.atlassian.plugin.osgi.event.PluginServiceDependencyWaitEndedEvent;
  import com.atlassian.plugin.osgi.event.PluginServiceDependencyWaitStartingEvent;
  import com.atlassian.plugin.osgi.event.PluginServiceDependencyWaitTimedOutEvent;
  import com.atlassian.plugin.osgi.external.ListableModuleDescriptorFactory;
  import com.atlassian.plugin.util.PluginUtils;
  import org.apache.commons.lang.Validate;
  import org.dom4j.Element;
  import org.osgi.framework.Bundle;
  import org.osgi.framework.BundleContext;
  import org.osgi.framework.BundleEvent;
  import org.osgi.framework.BundleException;
  import org.osgi.framework.BundleListener;
  import org.osgi.framework.ServiceReference;
  import org.osgi.framework.SynchronousBundleListener;
  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.net.URL;
  import java.util.HashMap;
  import java.util.Map;
  import java.util.Set;
  import java.util.concurrent.CopyOnWriteArraySet;
  
  /**
   * Plugin that wraps an OSGi bundle that does contain a plugin descriptor.  The actual bundle is not created until the
   * {@link #install()} method is invoked.  Any attempt to access a method that requires a bundle will throw an
   * {@link com.atlassian.plugin.IllegalPluginStateException}.
   *
   * This class uses a {@link OsgiPluginHelper} to represent different behaviors of key methods in different states.
   * {@link OsgiPluginUninstalledHelper} implements the methods when the plugin hasn't yet been installed into the
   * OSGi container, while {@link OsgiPluginInstalledHelper} implements the methods when the bundle is available.  This
   * leaves this class to manage the {@link PluginState} and interactions with the event system.
   */
  //@Threadsafe
  public class OsgiPlugin extends AbstractPlugin implements AutowireCapablePlugin, ContainerManagedPlugin, PluginArtifactBackedPlugin
  {
      private final Map<String, Element> moduleElements = new HashMap<String, Element>();
      private final PluginEventManager pluginEventManager;
      private final PackageAdmin packageAdmin;
  
      private final Set<OutstandingDependency> outstandingDependencies = new CopyOnWriteArraySet<OutstandingDependency>();
      private volatile boolean treatSpringBeanFactoryCreationAsRefresh = false;
      private volatile OsgiPluginHelper helper;
      public static final String ATLASSIAN_PLUGIN_KEY = "Atlassian-Plugin-Key";
      private final Logger log = LoggerFactory.getLogger(this.getClass());
      private final BundleListener bundleStopListener;
      private final PluginArtifact originalPluginArtifact;
  
      // Until the framework is actually done starting we want to ignore @RequiresRestart. Where this comes into play
      // is when we have one version of a plugin (e.g. via bundled-plugins.zip) installed but then discover a newer
      // one in installed-plugins. Clearly we can't "require a restart" between those two stages. And since nothing has
      // been published outside of plugins yet (and thus can't be cached by the host app) the @RequiresRestart is
      // meaningless.
      private volatile boolean frameworkStarted = false;
  
      public OsgiPlugin(final String key, final OsgiContainerManager mgr, final PluginArtifact artifact, final PluginArtifact originalPluginArtifact, final PluginEventManager pluginEventManager)
      {
          Validate.notNull(key, "The plugin key is required");
          Validate.notNull(mgr, "The osgi container is required");
          Validate.notNull(artifact, "The osgi container is required");
          Validate.notNull(pluginEventManager, "The osgi container is required");
  
          this.originalPluginArtifact = originalPluginArtifact;
          this.helper = new OsgiPluginUninstalledHelper(key, mgr, artifact);
          this.pluginEventManager = pluginEventManager;
          this.packageAdmin = extractPackageAdminFromOsgi(mgr);
          this.bundleStopListener = new SynchronousBundleListener()
          {
              public void bundleChanged(final BundleEvent bundleEvent)
              {
                  if ((bundleEvent.getBundle() == getBundle()) && (bundleEvent.getType() == BundleEvent.STOPPING))
                  {
                      helper.onDisable();
                      setPluginState(PluginState.DISABLED);
                  }
              }
         };
     }
 
     /**
      * Only used for testing
      * @param helper The helper to use
      */
     OsgiPlugin(PluginEventManager pluginEventManager, OsgiPluginHelper helper)
     {
         this.helper = helper;
         this.pluginEventManager = pluginEventManager;
         this.packageAdmin = null;
         this.bundleStopListener = null;
         this.originalPluginArtifact = null;
     }
 
     /**
      * @return The active bundle
      * @throws IllegalPluginStateException if the bundle hasn't been created yet
      */
     public Bundle getBundle() throws IllegalPluginStateException
     {
         return helper.getBundle();
     }
 
     /**
      * @return true
      */
     public boolean isUninstallable()
     {
         return true;
     }
 
     /**
      * @return true
      */
     public boolean isDynamicallyLoaded()
     {
         return true;
     }
 
     /**
      * @return true
      */
     public boolean isDeleteable()
     {
         return true;
     }
 
     public PluginArtifact getPluginArtifact()
     {
         return originalPluginArtifact;
     }
 
     /**
      *
      * @param clazz        The name of the class to be loaded
      * @param callingClass The class calling the loading (used to help find a classloader)
      * @param <T> The class type
      * @return The class instance, loaded from the OSGi bundle
      * @throws ClassNotFoundException If the class cannot be found
      * @throws IllegalPluginStateException if the bundle hasn't been created yet
      */
     public <T> Class<T> loadClass(final String clazz, final Class<?> callingClass) throws ClassNotFoundException, IllegalPluginStateException
     {
         return helper.loadClass(clazz, callingClass);
     }
 
     /**
      * @param name The resource name
      * @return The resource URL, null if not found
      * @throws IllegalPluginStateException if the bundle hasn't been created yet
      */
     public URL getResource(final String name) throws IllegalPluginStateException
     {
         return helper.getResource(name);
     }
 
     /**
      * @param name The name of the resource to be loaded.
      * @return Null if not found
      * @throws IllegalPluginStateException if the bundle hasn't been created yet
      */
     public InputStream getResourceAsStream(final String name) throws IllegalPluginStateException
     {
         return helper.getResourceAsStream(name);
     }
 
     /**
      * @return The classloader to load classes and resources from the bundle
      * @throws IllegalPluginStateException if the bundle hasn't been created yet
      */
     public ClassLoader getClassLoader() throws IllegalPluginStateException
     {
         return helper.getClassLoader();
     }
 
     /**
      * Called when the spring context for the bundle has failed to be created.  This means the bundle is still
      * active, but the Spring context is not available, so for our purposes, the plugin shouldn't be enabled.
      *
      * @param event The plugin container failed event
      * @throws com.atlassian.plugin.IllegalPluginStateException If the plugin key hasn't been set yet
      */
     @PluginEventListener
     public void onSpringContextFailed(final PluginContainerFailedEvent event) throws IllegalPluginStateException
     {
         if (getKey() == null)
         {
             throw new IllegalPluginStateException("Plugin key must be set");
         }
         if (getKey().equals(event.getPluginKey()))
         {
             logAndClearOustandingDependencies();
             // TODO: do something with the exception more than logging
             getLog().error("Unable to start the Spring context for plugin " + getKey(), event.getCause());
             setPluginState(PluginState.DISABLED);
         }
     }
 
     @PluginEventListener
     public void onPluginFrameworkStartedEvent(final PluginFrameworkStartedEvent event)
     {
         frameworkStarted = true;
     }
 
     @PluginEventListener
     public void onPluginFrameworkShutdownEvent(final PluginFrameworkShutdownEvent event)
     {
         frameworkStarted = false;
     }
 
     @PluginEventListener
     public void onServiceDependencyWaitStarting(PluginServiceDependencyWaitStartingEvent event)
     {
         if (event.getPluginKey() != null && event.getPluginKey().equals(getKey()))
         {
             OutstandingDependency dep = new OutstandingDependency(event.getBeanName(), String.valueOf(event.getFilter()));
             outstandingDependencies.add(dep);
             getLog().info(generateOutstandingDependencyLogMessage(dep, "Waiting for"));
         }
     }
 
     @PluginEventListener
     public void onServiceDependencyWaitEnded(PluginServiceDependencyWaitEndedEvent event)
     {
         if (event.getPluginKey() != null && event.getPluginKey().equals(getKey()))
         {
             OutstandingDependency dep = new OutstandingDependency(event.getBeanName(), String.valueOf(event.getFilter()));
             outstandingDependencies.remove(dep);
             getLog().info(generateOutstandingDependencyLogMessage(dep, "Found"));
         }
     }
 
     @PluginEventListener
     public void onServiceDependencyWaitEnded(PluginServiceDependencyWaitTimedOutEvent event)
     {
         if (event.getPluginKey() != null && event.getPluginKey().equals(getKey()))
         {
             OutstandingDependency dep = new OutstandingDependency(event.getBeanName(), String.valueOf(event.getFilter()));
             outstandingDependencies.remove(dep);
             getLog().error(generateOutstandingDependencyLogMessage(dep, "Timeout waiting for "));
         }
     }
 
     private String generateOutstandingDependencyLogMessage(OutstandingDependency dep, String action)
     {
         StringBuilder sb = new StringBuilder();
         sb.append(action).append(" ");
         sb.append("service '").append(dep.getBeanName()).append("' for plugin '").append(getKey()).append("' with filter ").append(dep.getFilter());
         return sb.toString();
     }
 
     /**
      * Called when the spring context for the bundle has been created or refreshed.  If this is the first time the
      * context has been refreshed, then it is a new context.  Otherwise, this means that the bundle has been reloaded,
      * usually due to a dependency upgrade.
      *
      * @param event The event
      * @throws com.atlassian.plugin.IllegalPluginStateException If the plugin key hasn't been set yet
      */
     @PluginEventListener
     public void onSpringContextRefresh(final PluginContainerRefreshedEvent event) throws IllegalPluginStateException
     {
         if (getKey() == null)
         {
             throw new IllegalPluginStateException("Plugin key must be set");
         }
         if (getKey().equals(event.getPluginKey()))
         {
             outstandingDependencies.clear();
             helper.setPluginContainer(event.getContainer());
             if (!compareAndSetPluginState(PluginState.ENABLING, PluginState.ENABLED) &&
                 getPluginState() != PluginState.ENABLED)
             {
                 log.warn("Ignoring the Spring context that was just created for plugin " + getKey() + ".  The plugin " +
                           "is in an invalid state, " + getPluginState() + ", that doesn't support a transition to " +
                           "enabled.  Most likely, it was disabled due to a timeout.");
                 helper.setPluginContainer(null);
                 return;
             }
 
             // Only send refresh event on second creation
             if (treatSpringBeanFactoryCreationAsRefresh)
             {
                 pluginEventManager.broadcast(new PluginRefreshedEvent(this));
             }
             else
             {
                 treatSpringBeanFactoryCreationAsRefresh = true;
             }
         }
     }
 
     /**
      * Creates and autowires the class, using Spring's autodetection algorithm
      *
      * @throws IllegalPluginStateException if the bundle hasn't been created yet
      */
     public <T> T autowire(final Class<T> clazz) throws IllegalPluginStateException
     {
         return autowire(clazz, AutowireStrategy.AUTOWIRE_AUTODETECT);
     }
 
     /**
      * Creates and autowires the class
      *
      * @throws IllegalPluginStateException if the bundle hasn't been created yet
      */
     public <T> T autowire(final Class<T> clazz, final AutowireStrategy autowireStrategy) throws IllegalPluginStateException
     {
         return helper.autowire(clazz, autowireStrategy);
     }
 
     /**
      * Autowires the instance using Spring's autodetection algorithm
      *
      * @throws IllegalPluginStateException if the bundle hasn't been created yet
      */
     public void autowire(final Object instance) throws IllegalStateException
     {
         autowire(instance, AutowireStrategy.AUTOWIRE_AUTODETECT);
     }
 
     /**
      * Autowires the instance
      *
      * @throws IllegalPluginStateException if the bundle hasn't been created yet
      */
     public void autowire(final Object instance, final AutowireStrategy autowireStrategy) throws IllegalPluginStateException
     {
         helper.autowire(instance, autowireStrategy);
     }
 
     /**
      * Determines which plugins are required for this one to operate based on tracing the "wires" or packages that
      * are imported by this plugin.  Bundles that provide those packages are determined to be required plugins.
      *
      * @return A set of bundle symbolic names, or plugin keys.  Empty set if none.
      * @since 2.2.0
      */
     @Override
     public Set<String> getRequiredPlugins() throws IllegalPluginStateException
     {
         return helper.getRequiredPlugins();
     }
 
     @Override
     public String toString()
     {
         return getKey();
     }
 
     /**
      * Installs the plugin artifact into OSGi
      *
      * @throws IllegalPluginStateException if the bundle hasn't been created yet
      */
     @Override
     protected void installInternal() throws IllegalPluginStateException
     {
         Bundle bundle = helper.install();
         helper = new OsgiPluginInstalledHelper(bundle, packageAdmin);
     }
 
     /**
      * Enables the plugin by setting the OSGi bundle state to enabled.
      *
      * @return {@link PluginState#ENABLED}if spring isn't necessory or {@link PluginState#ENABLING} if we are waiting
      * on a spring context
      * @throws OsgiContainerException If the underlying OSGi system threw an exception or we tried to enable the bundle
      * when it was in an invalid state
      * @throws IllegalPluginStateException if the bundle hasn't been created yet
      */
     @Override
     protected synchronized PluginState enableInternal() throws OsgiContainerException, IllegalPluginStateException
     {
         PluginState stateResult;
         try
         {
             if (getBundle().getState() == Bundle.ACTIVE)
             {
                 stateResult = PluginState.ENABLED;
             }
             else if ((getBundle().getState() == Bundle.RESOLVED) || (getBundle().getState() == Bundle.INSTALLED))
             {
                 pluginEventManager.register(this);
                 if (!treatSpringBeanFactoryCreationAsRefresh)
                 {
                     stateResult = PluginState.ENABLING;
                     // Set it immediately, since the Spring context refresh event could happen at any time
                     setPluginState(stateResult);
                 }
                 else
                 {
                     stateResult = PluginState.ENABLED;
                 }
                 getBundle().start();
                 final BundleContext ctx = getBundle().getBundleContext();
                 helper.onEnable(
                         new ServiceTracker(ctx, ModuleDescriptor.class.getName(),
                                 new ModuleDescriptorServiceTrackerCustomizer(this, pluginEventManager)),
                         new ServiceTracker(ctx, ListableModuleDescriptorFactory.class.getName(),
                                 new UnrecognizedModuleDescriptorServiceTrackerCustomizer(this, pluginEventManager)));
 
                 // ensure the bean factory is removed when the bundle is stopped
                 ctx.addBundleListener(bundleStopListener);
             }
             else
             {
                 throw new OsgiContainerException("Cannot enable the plugin '" + getKey() + "' when the bundle is not in the resolved or installed state: "
                         + getBundle().getState() + "(" + getBundle().getBundleId() + ")");
             }
 
             // Only set state to enabling if it hasn't already been enabled via another thread notifying of a spring
             // application context creation during the execution of this method
             return (getPluginState() != PluginState.ENABLED ? stateResult : PluginState.ENABLED);
         }
         catch (final BundleException e)
         {
             log.error("Detected an error (BundleException) enabling the plugin '" + getKey() + "' : " + e.getMessage() + ". " +
                       " This error usually occurs when your plugin imports a package from another bundle with a specific version constraint " +
                     "and either the bundle providing that package doesn't meet those version constraints, or there is no bundle " +
                     "available that provides the specified package. For more details on how to fix this, see " +
                     "http://confluence.atlassian.com/x/1xy6D");
             throw new OsgiContainerException("Cannot start plugin: " + getKey(), e);
         }
     }
 
     /**
      * Disables the plugin by changing the bundle state back to resolved
      *
      * @throws OsgiContainerException If the OSGi system threw an exception
      * @throws IllegalPluginStateException if the bundle hasn't been created yet
      */
     @Override
     protected synchronized void disableInternal() throws OsgiContainerException, IllegalPluginStateException
     {
         // Only disable underlying bundle if this is a truly dynamic plugin
         if (!requiresRestart())
         {
             try
             {
                 if (getPluginState() == PluginState.DISABLING)
                 {
                     logAndClearOustandingDependencies();
                 }
                 helper.onDisable();
                 pluginEventManager.unregister(this);
                 getBundle().stop();
                 treatSpringBeanFactoryCreationAsRefresh = false;
             }
             catch (final BundleException e)
             {
                 throw new OsgiContainerException("Cannot stop plugin: " + getKey(), e);
             }
         }
     }
 
     private boolean requiresRestart()
     {
         return frameworkStarted && PluginUtils.doesPluginRequireRestart(this);
     }
 
     private void logAndClearOustandingDependencies()
     {
         for (OutstandingDependency dep : outstandingDependencies)
         {
             getLog().error(generateOutstandingDependencyLogMessage(dep, "Never resolved"));
         }
         outstandingDependencies.clear();
     }
 
     /**
      * Uninstalls the bundle from the OSGi container
      * @throws OsgiContainerException If the underlying OSGi system threw an exception
      * @throws IllegalPluginStateException if the bundle hasn't been created yet
      */
     @Override
     protected void uninstallInternal() throws OsgiContainerException, IllegalPluginStateException
     {
         try
         {
             if (getBundle().getState() != Bundle.UNINSTALLED)
             {
                 pluginEventManager.unregister(this);
                 getBundle().uninstall();
                 helper.onUninstall();
                 setPluginState(PluginState.UNINSTALLED);
             }
         }
         catch (final BundleException e)
         {
             throw new OsgiContainerException("Cannot uninstall bundle " + getBundle().getSymbolicName());
         }
     }
 
     /**
      * Adds a module descriptor XML element for later processing, needed for dynamic module support
      *
      * @param key The module key
      * @param element The module element
      */
     void addModuleDescriptorElement(final String key, final Element element)
     {
         moduleElements.put(key, element);
     }
 
     /**
      * Exposes {@link #removeModuleDescriptor(String)} for package-protected classes
      *
      * @param key The module descriptor key
      */
     void clearModuleDescriptor(String key)
     {
         removeModuleDescriptor(key);
     }
 
     /**
      * Gets the module elements for dynamic module descriptor handling.  Doesn't need to return a copy or anything
      * immutable because it is only accessed by package-private helper classes
      *
      * @return The map of module keys to module XML elements
      */
     Map<String, Element> getModuleElements()
     {
         return moduleElements;
     }
 
     /**
      * Extracts the {@link PackageAdmin} instance from the OSGi container
      * @param mgr The OSGi container manager
      * @return The package admin instance, should never be null
      */
     private PackageAdmin extractPackageAdminFromOsgi(OsgiContainerManager mgr)
     {
         // Get the system bundle (always bundle 0)
         Bundle bundle = mgr.getBundles()[0];
 
         // We assume the package admin will always be available
         final ServiceReference ref = bundle.getBundleContext()
                 .getServiceReference(PackageAdmin.class.getName());
         return (PackageAdmin) bundle.getBundleContext()
                 .getService(ref);
     }
 
     public ContainerAccessor getContainerAccessor()
     {
         return helper.getContainerAccessor();
     }
 
     private static class OutstandingDependency
     {
         private final String beanName;
         private final String filter;
 
         public OutstandingDependency(String beanName, String filter)
         {
             this.beanName = beanName;
             this.filter = filter;
         }
 
         public String getBeanName()
         {
             return beanName;
         }
 
         public String getFilter()
         {
             return filter;
         }
 
         @Override
         public boolean equals(Object o)
         {
             if (this == o)
             {
                 return true;
             }
             if (o == null || getClass() != o.getClass())
             {
                 return false;
             }
 
             OutstandingDependency that = (OutstandingDependency) o;
 
             if (beanName != null ? !beanName.equals(that.beanName) : that.beanName != null)
             {
                 return false;
             }
             if (!filter.equals(that.filter))
             {
                 return false;
             }
 
             return true;
         }
 
         @Override
         public int hashCode()
         {
             int result = beanName != null ? beanName.hashCode() : 0;
             result = 31 * result + filter.hashCode();
             return result;
         }
     }
 }