package com.atlassian.plugin.web.descriptors;
   
   import com.atlassian.plugin.Plugin;
   import com.atlassian.plugin.PluginParseException;
   import com.atlassian.plugin.descriptors.AbstractModuleDescriptor;
   import com.atlassian.plugin.module.ModuleFactory;
   import com.atlassian.plugin.util.validation.ValidationPattern;
   import com.atlassian.plugin.web.renderer.WebPanelRenderer;
   import org.dom4j.Element;
  
  import static com.atlassian.plugin.util.validation.ValidationPattern.test;
  
  /**
   * The web panel renderer module is used to add web panel renderers to the
   * plugin system.
   *
   * @since 2.5.0
   */
  public class WebPanelRendererModuleDescriptor extends AbstractModuleDescriptor<WebPanelRenderer> {
      /**
       * Host applications should use this string when registering the
       * {@link WebPanelRendererModuleDescriptor}.
       */
      public static final String XML_ELEMENT_NAME = "web-panel-renderer";
      private WebPanelRenderer rendererModule;
  
      public WebPanelRendererModuleDescriptor(ModuleFactory moduleClassFactory) {
          super(moduleClassFactory);
      }
  
      @Override
      public void init(Plugin plugin, Element element) throws PluginParseException {
          super.init(plugin, element);
      }
  
      @Override
      protected void provideValidationRules(ValidationPattern pattern) {
          super.provideValidationRules(pattern);
          pattern.
                  rule(
                          test("@class").withError("The class is required"));
      }
  
      @Override
      public void enabled() {
          super.enabled();
          if (!(WebPanelRenderer.class.isAssignableFrom(getModuleClass()))) {
              throw new PluginParseException(String.format(
                      "Supplied module class (%s) is not a %s", getModuleClass().getName(), WebPanelRenderer.class.getName()));
          }
      }
  
      @Override
      public WebPanelRenderer getModule() {
          if (rendererModule == null) {
              rendererModule = moduleFactory.createModule(moduleClassName, this);
          }
          return rendererModule;
      }
  }