package com.atlassian.plugin.osgi.external;
   
   import com.atlassian.plugin.ModuleDescriptor;
   import com.atlassian.plugin.PluginParseException;
   import com.atlassian.plugin.hostcontainer.HostContainer;
   import com.google.common.collect.ImmutableSet;
   
   import java.util.Set;
   
  /**
   * A single module descriptor factory for plugins to use when they want to expose just one plugin. Uses
   * {@link HostContainer} to optionally provide autowiring for new descriptor instances.
   *
   * @since 2.1
   */
  public class SingleModuleDescriptorFactory<T extends ModuleDescriptor> implements ListableModuleDescriptorFactory {
      private final String type;
      private final Class<T> moduleDescriptorClass;
      private final HostContainer hostContainer;
  
      /**
       * Constructs an instance using a specific host container
       *
       * @param hostContainer         The host container to use to create descriptor instances
       * @param type                  The type of module
       * @param moduleDescriptorClass The descriptor class
       * @since 2.2.0
       */
      public SingleModuleDescriptorFactory(final HostContainer hostContainer, final String type, final Class<T> moduleDescriptorClass) {
          this.moduleDescriptorClass = moduleDescriptorClass;
          this.type = type;
          this.hostContainer = hostContainer;
      }
  
      @Override
      public ModuleDescriptor getModuleDescriptor(final String type) throws PluginParseException, IllegalAccessException, InstantiationException, ClassNotFoundException {
          T result = null;
          if (this.type.equals(type)) {
              result = hostContainer.create(moduleDescriptorClass);
          }
          return result;
      }
  
      @Override
      public boolean hasModuleDescriptor(final String type) {
          return (this.type.equals(type));
      }
  
      @Override
      public Class<? extends ModuleDescriptor> getModuleDescriptorClass(final String type) {
          return (this.type.equals(type) ? moduleDescriptorClass : null);
      }
  
      /**
       * @since 3.0.0
       */
      @Override
      public Iterable<String> getModuleDescriptorKeys() {
          return ImmutableSet.of(type);
      }
  
      @Override
      public Set<Class<? extends ModuleDescriptor>> getModuleDescriptorClasses() {
          return ImmutableSet.of(moduleDescriptorClass);
      }
  
      public HostContainer getHostContainer() {
          return hostContainer;
      }
  }