content: package ganymede.notebook;
  /*-
   * ##########################################################################
   * Ganymede
   * %%
   * Copyright (C) 2021 - 2024 Allen D. Ball
   * %%
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   * ##########################################################################
   */
  import com.fasterxml.jackson.databind.node.ObjectNode;
  import java.util.Base64;
  import java.util.Optional;
  
  import static org.springframework.util.MimeTypeUtils.TEXT_PLAIN_VALUE;
  
  /**
   * {@link ganymede.server.Message#mime_bundle(Object,Object...)} output
   * {@link Renderer}.
   *
   * @author {@link.uri mailto:ball@hcf.dev Allen D. Ball}
   */
  public interface Renderer {
      public static final String DATA = "data";
      public static final String METADATA = "metadata";
  
      /**
       * Singleton {@link RendererMap} instance.
       */
      public static final RendererMap MAP = new RendererMap();
  
      /**
       * {@link Base64.Encoder} instance.
       */
      public static final Base64.Encoder BASE64_ENCODER = Base64.getEncoder();
  
      /**
       * Method to get a configured instance of this {@link Renderer}.
       * Subclasses may override to return an instance that requires
       * additional resources and/or configuration.  Default implementaion
       * returns {@link.this}.
       *
       * @return  An {@link Optional} containing the configured instance.
       */
      public default Optional<? extends Renderer> instance() {
          return Optional.of(this);
      }
  
      /**
       * Default method to analyze {@link.this} instance for {@link ForClass}
       * and {@link ForClassName} annotations.  May return {@code null} if a
       * {@link Class} cannot be loaded.
       *
       * @return  The {@link Class type} the argument renders (may be
       *          {@code null}).
       */
      public default Class<?> getRenderType() {
          return getRenderType(getClass());
      }
  
      /**
       * {@link RendererMap} configuration method.
       *
       * @param   renderers       The {@link RendererMap}.
       */
      public void configure(RendererMap renderers);
  
      /**
       * Method to render an {@link Object} to a {@code mime-bundle}.
       *
       * @param   bundle          The {@link ganymede.server.Message}
       *                          {@code mime-bundle}.
       * @param   object          The {@link Object} to render.
       */
      public default void renderTo(ObjectNode bundle, Object object) {
          if (! bundle.with(DATA).has(TEXT_PLAIN_VALUE)) {
              bundle.with(DATA).put(TEXT_PLAIN_VALUE, String.valueOf(object));
          }
      }
  
      /**
       * Static method to analyze a class for {@link ForClass} and
       * {@link ForClassName} annotations.  May return {@code null} if a
       * {@link Class} cannot be loaded.
       *
       * @param   type            The {@link Class} to analyze.
       *
       * @return  The {@link Class type} the argument renders (may be
       *          {@code null}).
       */
      public static Class<?> getRenderType(Class<?> type) {
          Class<?> renderType = null;
  
          if (type != null) {
              try {
                  if (type.isAnnotationPresent(ForClassName.class)) {
                      var name = type.getAnnotation(ForClassName.class).value();
  
                      renderType = Class.forName(name, false, type.getClassLoader());
                  } else {
                      renderType = type.getAnnotation(ForClass.class).value();
                  }
              } catch (Throwable throwable) {
              }
  
              if (renderType == null) {
                  var superType = type.getSuperclass();
  
                  if (superType != null && Renderer.class.isAssignableFrom(superType)) {
                      renderType = getRenderType(superType);
                  }
              }
          }
  
          return renderType;
      }
  }
  