content: /*
   *  Licensed to the Apache Software Foundation (ASF) under one
   *  or more contributor license agreements.  See the NOTICE file
   *  distributed with this work for additional information
   *  regarding copyright ownership.  The ASF licenses this file
   *  to you 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.
   */
  package org.apache.causeway.applib.services.publishing.spi;
  
  import java.util.List;
  import java.util.function.Supplier;
  
  import org.jspecify.annotations.Nullable;
  
  import org.apache.causeway.applib.services.bookmark.Bookmark;
  import org.apache.causeway.commons.having.HasEnabling;
  
  /**
   * Part of the <i>Publishing SPI</i>. A component to receive notifaction that a domain object
   * or a standalone list of domain objects has been rendered.
   *
   * @since 2.0 {@index}
   */
  public interface PageRenderSubscriber extends HasEnabling {
  
      /**
       * Enumerates the different types of pages that can be rendered.
       */
      public enum PageType {
          /**
           * Either a view model or an entity.
           */
          DOMAIN_OBJECT,
          /**
           * A collection of view models or entities.
           */
          COLLECTION,
          /**
           * A single value
           */
          VALUE,
          /**
           * Anything else; might include void, or sign in pages.
           */
          OTHER;
      }
  
      /**
       * Called just before the rendering process starts.
       *
       * <p>
       *     Determines which of the <code>onRenderedXxx</code> callbacks (if any) will next be called:
       *     <ul>
       *         <li>if {@link PageType#DOMAIN_OBJECT}, then will call {@link #onRenderingDomainObject(Bookmark)} next,
       *             and afterwards {@link #onRenderedDomainObject(Bookmark)} next</li>
       *         <li>if {@link PageType#COLLECTION}, then will call {@link #onRenderedCollection(Supplier)} next</li>
       *         <li>if {@link PageType#VALUE}, then will call {@link #onRenderedValue(Object)} next</li>
       *     </ul>
       *     However, if {@link PageType#OTHER}, then <b>NO</b> <code>onRenderedXxx</code> method will be called.
       * </p>
       *
       * <p>
       *     Also, if any of the pages fail to render (eg due to an authorization exception), then - again -
       *     <b>NO</b> <code>onRenderedXxx</code> method will be called
       * </p>
       *
       * <p>
       *     Implementations could use this to start a stopwatch, for example, or to reset caches.
       * </p>
       *
       * @param pageType - determines which of the subsequent <code>onRenderedXxx</code> callbacks (if any) will next be called.
       */
      default void onRendering(final PageType pageType) {}
  
      /**
       * Indicates that the domain object represented by the {@link Bookmark} is about to be rendered.
       *
       * @param bookmark - representation of the domain object that are to be rendered.
       */
      default void onRenderingDomainObject(final Bookmark bookmark) {}
  
      /**
       * Indicates that a standalone list of domain objects (each represented by a {@link Bookmark} is about to be rendered.
       *
       * @param bookmarkSupplier - a supplier representations of the collection of domain objects that are to be rendered.  The level of indirection is for performance (in case no implementation is interested)
       */
      default void onRenderingCollection(final Supplier<List<Bookmark>> bookmarkSupplier) {}
  
      /**
       * Indicates that a value is about to be rendered.
       *
       * @param value - the actual value that is to be rendered.
       */
      default void onRenderingValue(final @Nullable Object value) {}
  
      /**
       * Indicates that the domain object represented by the {@link Bookmark} has been rendered.
       *
       * @param bookmark - representation of the domain object that has been rendered.
       */
      default void onRenderedDomainObject(final Bookmark bookmark) {}
  
      /**
       * Indicates that a standalone list of domain objects (each represented by a {@link Bookmark} has been rendered.
       *
       * @param bookmarkSupplier - a supplier representations of the collection of domain objects that have been rendered.  The level of indirection is for performance (in case no implementation is interested)
       */
      default void onRenderedCollection(final Supplier<List<Bookmark>> bookmarkSupplier) {}
  
      /**
       * Indicates that a value has been rendered.
       *
       * @param value - the actual value that has been rendered.
       */
      default void onRenderedValue(final @Nullable Object value) {}
  
  }
  