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.viewer.wicket.ui.util;
  
  import java.util.UUID;
  
  import org.apache.wicket.IRequestListener;
  import org.apache.wicket.markup.html.link.Link;
  import org.apache.wicket.markup.html.link.ResourceLink;
  import org.apache.wicket.request.cycle.RequestCycle;
  import org.apache.wicket.request.mapper.parameter.PageParameters;
  import org.apache.wicket.request.resource.IResource;
  import org.apache.wicket.request.resource.IResource.Attributes;
  
  /**
   * Each ResourceLinkVolatile instance generates a unique URL, which
   * effectively eliminates any caching during the request response cycle.
   * <p>
   * This is the desired behavior for Blob/Clob 'download' buttons.
   *
   * @since 2.0
   * @implNote this is almost a copy of Wicket's {@link ResourceLink}.
   */
  public class ResourceLinkVolatile extends Link<Object> implements IRequestListener {
      private static final long serialVersionUID = 1L;
  
      /** The Resource */
      private final IResource resource;
  
      /** The resource parameters */
      private final PageParameters resourceParameters;
  
      /**
       * Constructs a link directly to the provided resource.
       *
       * @param id       See Component
       * @param resource The resource
       */
      public ResourceLinkVolatile(final String id, final IResource resource) {
          super(id);
          this.resource = resource;
          this.resourceParameters = new PageParameters()
                  .add("antiCache", UUID.randomUUID().toString());
      }
  
      @Override
      public void onClick() {
      }
  
      @Override
      public boolean rendersPage() {
          return false;
      }
  
      @Override
      protected boolean getStatelessHint() {
          return false;
      }
  
      @Override
      protected final CharSequence getURL() {
          return urlForListener(resourceParameters);
      }
  
      @Override
      public final void onRequest() {
          Attributes a = new Attributes(RequestCycle.get().getRequest(), RequestCycle.get().getResponse(), null);
          resource.respond(a);
  
          super.onRequest();
      }
  }
  