package com.atlassian.plugin.osgi.spring;
   
   import org.eclipse.gemini.blueprint.context.event.OsgiBundleApplicationContextEvent;
   import org.eclipse.gemini.blueprint.context.event.OsgiBundleApplicationContextEventMulticasterAdapter;
   import org.eclipse.gemini.blueprint.context.event.OsgiBundleApplicationContextListener;
   import org.osgi.framework.BundleContext;
   import org.osgi.framework.InvalidSyntaxException;
   import org.osgi.framework.ServiceEvent;
   import org.osgi.framework.ServiceReference;
  import org.springframework.context.ApplicationListener;
  import org.springframework.context.event.SimpleApplicationEventMulticaster;
  
  /**
   * Finds ApplicationListener bridge and uses it to CC all event broadcasts
   *
   * @since 2.2.1
   */
  public class PluginBridgeEventMulticaster extends OsgiBundleApplicationContextEventMulticasterAdapter {
      private volatile OsgiBundleApplicationContextListener bridgeListener;
  
      /**
       * Look for the application listener bridge from atlassian-plugins-osgi-bridge. Can't use Spring DM stuff as it
       * creates a circular dependency.
       */
      public PluginBridgeEventMulticaster(final BundleContext bundleContext) {
          super(new SimpleApplicationEventMulticaster());
  
          String filter = "(&(objectClass=" + OsgiBundleApplicationContextListener.class.getName() + ")(plugin-bridge=true))";
  
          ServiceReference[] refs;
          try {
              refs = bundleContext.getAllServiceReferences(ApplicationListener.class.getName(), filter);
              if (refs != null && refs.length == 1) {
                  bridgeListener = (OsgiBundleApplicationContextListener) bundleContext.getService(refs[0]);
              }
  
              // Add listener to catch the extremely rare case of a late deployment or upgrade
              bundleContext.addServiceListener(serviceEvent -> {
                  switch (serviceEvent.getType()) {
                      case ServiceEvent.MODIFIED:
                          // falling through intentionally
                      case ServiceEvent.REGISTERED:
                          bridgeListener = (OsgiBundleApplicationContextListener) bundleContext.getService(serviceEvent.getServiceReference());
                          break;
                      case ServiceEvent.UNREGISTERING:
                          bridgeListener = null;
                          break;
                  }
              }, filter);
          } catch (InvalidSyntaxException e) {
              // Should never happen
              throw new RuntimeException("Invalid LDAP filter", e);
          }
      }
  
      @Override
      public void multicastEvent(OsgiBundleApplicationContextEvent applicationEvent) {
          super.multicastEvent(applicationEvent);
          if (bridgeListener != null)
              bridgeListener.onOsgiApplicationEvent(applicationEvent);
      }
  }