package com.atlassian.plugin.web.model;
   
   import com.atlassian.plugin.Plugin;
   import com.atlassian.plugin.PluginAccessor;
   import com.atlassian.plugin.web.descriptors.WebPanelRendererModuleDescriptor;
   import com.atlassian.plugin.web.renderer.RendererException;
   import com.atlassian.plugin.web.renderer.StaticWebPanelRenderer;
   import com.atlassian.plugin.web.renderer.WebPanelRenderer;
   import com.google.common.base.Preconditions;
  import com.google.common.base.Predicate;
  import com.google.common.collect.Iterables;
  
  import java.io.IOException;
  import java.io.Writer;
  import java.util.Map;
  import java.util.NoSuchElementException;
  
  /**
   * @since   2.5.0
   */
  public abstract class AbstractWebPanel implements WebPanel
  {
      private final PluginAccessor pluginAccessor;
      protected Plugin plugin;
      private String resourceType;
  
      protected AbstractWebPanel(PluginAccessor pluginAccessor)
      {
          this.pluginAccessor = pluginAccessor;
      }
  
      public void setPlugin(Plugin plugin)
      {
          this.plugin = plugin;
      }
  
      public void setResourceType(String resourceType)
      {
          this.resourceType = Preconditions.checkNotNull(resourceType);
      }
  
      /**
       * Default implementation of {@link WebPanel#writeHtml(java.io.Writer, java.util.Map)} that delegates to
       * {@link WebPanel#getHtml(java.util.Map)}. This method is provided for backwards compatibility with
       * pre-2.11 implementations of WebPanel. Panels SHOULD be upgraded to support this method natively
       * for performance reasons.
       *
       * @param writer the writer to append the panel output to
       * @param context the contextual information that can be used during
       *  rendering. Context elements are not standardized and are
       *  application-specific, so refer to your application's documentation to
       *  learn what is available.
       * @throws IOException
       */
      public void writeHtml(Writer writer, Map<String, Object> context) throws IOException
      {
          writer.write(getHtml(context));
      }
  
      protected final WebPanelRenderer getRenderer()
      {
          if (StaticWebPanelRenderer.RESOURCE_TYPE.equals(resourceType))
          {
              return StaticWebPanelRenderer.RENDERER;
          }
          else
          {
              // PERF hit the cache
              try
              {
                  return Iterables.find(pluginAccessor.getEnabledModuleDescriptorsByClass(
                      WebPanelRendererModuleDescriptor.class),
                      new Predicate<WebPanelRendererModuleDescriptor>()
                      {
                          @Override
                          public boolean apply(WebPanelRendererModuleDescriptor descriptor)
                          {
                              WebPanelRenderer webPanelRenderer = descriptor.getModule();
                              return (Preconditions.checkNotNull(resourceType).equals(webPanelRenderer.getResourceType()));
                          }
                      }).getModule();
              }
              catch (NoSuchElementException e)
              {
                  throw new RendererException("No renderer found for resource type: " + resourceType, e);
              }
          }
      }
  }