package com.atlassian.plugin.osgi.factory;
   
   import com.atlassian.plugin.ModuleDescriptor;
   import com.atlassian.plugin.event.PluginEventManager;
   import com.atlassian.plugin.event.events.PluginModuleAvailableEvent;
   import com.atlassian.plugin.event.events.PluginModuleUnavailableEvent;
   import org.osgi.framework.Bundle;
   import org.osgi.framework.ServiceReference;
   import org.osgi.util.tracker.ServiceTrackerCustomizer;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import static com.google.common.base.Preconditions.checkNotNull;
  
  /**
   * Tracks module descriptors registered as services, then updates the descriptors map accordingly
   *
   * @since 2.2.0
   */
  class ModuleDescriptorServiceTrackerCustomizer implements ServiceTrackerCustomizer {
      private static final Logger log = LoggerFactory.getLogger(ModuleDescriptorServiceTrackerCustomizer.class);
  
      private final Bundle bundle;
      private final OsgiPlugin plugin;
      private final PluginEventManager pluginEventManager;
  
      public ModuleDescriptorServiceTrackerCustomizer(OsgiPlugin plugin, PluginEventManager pluginEventManager) {
          this.plugin = checkNotNull(plugin);
          this.bundle = checkNotNull(plugin.getBundle());
          this.pluginEventManager = checkNotNull(pluginEventManager);
      }
  
      public Object addingService(final ServiceReference serviceReference) {
          ModuleDescriptor<?> descriptor = null;
          if (serviceReference.getBundle() == bundle) {
              descriptor = (ModuleDescriptor<?>) bundle.getBundleContext().getService(serviceReference);
              plugin.addModuleDescriptor(descriptor);
              if (log.isInfoEnabled()) {
                  log.info("Dynamically registered new module descriptor: " + descriptor.getCompleteKey());
              }
              pluginEventManager.broadcast(new PluginModuleAvailableEvent(descriptor));
          }
          return descriptor;
      }
  
      public void modifiedService(final ServiceReference serviceReference, final Object o) {
          // Don't bother doing anything as it only represents a change in properties
      }
  
      public void removedService(final ServiceReference serviceReference, final Object o) {
          if (serviceReference.getBundle() == bundle) {
              final ModuleDescriptor<?> descriptor = (ModuleDescriptor<?>) o;
              pluginEventManager.broadcast(new PluginModuleUnavailableEvent(descriptor));
              plugin.clearModuleDescriptor(descriptor.getKey());
              if (log.isInfoEnabled()) {
                  log.info("Dynamically removed module descriptor: " + descriptor.getCompleteKey());
              }
          }
      }
  }