/*
    * Copyright 2013 smartics, Kronseder & Reiner GmbH
    *
    * 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.
   */
  package de.smartics.properties.admin.resources.representation.share;
  
  import java.io.OutputStream;
  
  import javax.ws.rs.core.MediaType;
  import javax.ws.rs.core.MultivaluedMap;
  import javax.ws.rs.core.UriInfo;
  
  import de.smartics.properties.admin.resources.representation.html.share.HtmlPathHelper;
  import de.smartics.properties.utils.HtmlUtils;
  import de.smartics.resteasy.hypermedia.renderer.LinkDescriptor;
  import de.smartics.resteasy.hypermedia.renderer.LocalizationProvider;
  import de.smartics.resteasy.hypermedia.renderer.RepresentationRenderer;
  import de.smartics.resteasy.hypermedia.renderer.ResourceContext;
  import de.smartics.resteasy.hypermedia.resources.Resources;
  
  /**
   * Base implementation for document renderers.
   *
   * @param <T> the type of the resource the renderer is rendering representations
   *          for.
   */
  public abstract class AbstractRepresentationRenderer<T> implements
      RepresentationRenderer<T>
  {
    // ********************************* Fields *********************************
  
    // --- constants ------------------------------------------------------------
  
    // --- members --------------------------------------------------------------
  
    /**
     * The context information for representation renderers.
     */
    private final ResourceContext context;
  
    /**
     * The original stream to write to.
     */
    protected final OutputStream entityStream;
  
    /**
     * The character encoding to use to render the output.
     */
    protected final String characterEncoding;
  
    /**
     * Helper to localize application specific resources.
     */
    protected final HtmlPathHelper pathHelper;
  
    /**
     * The factory to create link descriptors.
     */
    protected final LinkDescriptorFactory linkDescriptorFactory;
  
    /**
     * The helper to create the breadcrumbs.
     */
    protected final BreadcrumbHelper breadcrumb;
  
    /**
     * Utilities to deal with HTML.
     */
    protected final HtmlUtils htmlUtils;
  
    // ****************************** Initializer *******************************
  
    // ****************************** Constructors ******************************
  
    /**
     * Default constructor using a stream.
     *
     * @param context the context information to render the representation.
     * @param characterEncoding the character encoding to use to render the
     *          output.
     * @param entityStream the stream to write to.
     * @param method the method to select the service method of the resource.
     */
    protected AbstractRepresentationRenderer(final ResourceContext context,
        final String characterEncoding, final OutputStream entityStream,
        final String method)
    {
      this.context = context;
     this.characterEncoding = characterEncoding;
     this.entityStream = entityStream;
     this.pathHelper = new HtmlPathHelper(context.getUriInfo());
 
     this.linkDescriptorFactory = createLinkDescriptorFactory();
     this.breadcrumb = new BreadcrumbHelper(linkDescriptorFactory, method);
     this.htmlUtils = new HtmlUtils(characterEncoding);
   }
 
   // ****************************** Inner Classes *****************************
 
   // ********************************* Methods ********************************
 
   // --- init -----------------------------------------------------------------
 
   private LinkDescriptorFactory createLinkDescriptorFactory()
   {
     final LocalizationProvider provider = context.getL7nProvider();
     final UriInfo uriInfo = context.getUriInfo();
     final LinkDescriptorFactory factory =
         new LinkDescriptorFactory(uriInfo, provider);
     return factory;
   }
 
   // --- get&set --------------------------------------------------------------
 
   // --- business -------------------------------------------------------------
 
   @Override
   public void render()
   {
     httpHeader();
     httpBody();
 
     close();
   }
 
   private void httpHeader()
   {
     final MediaType mediaType = context.getMediaType();
     final MultivaluedMap<String, Object> httpHeaders = context.getHttpHeaders();
     if (httpHeaders != null)
     {
       httpHeaders.add("Content-Type", mediaType + "; charset="
                                       + characterEncoding);
       renderApplicationStateHttpHeader(httpHeaders);
     }
   }
 
   private void renderApplicationStateHttpHeader(
       final MultivaluedMap<String, Object> httpHeaders)
   {
     final Resources discovery = context.getDiscovery();
     for (final LinkDescriptor link : discovery.links())
     {
       renderHttpHeaderLink(httpHeaders, link);
     }
 
     renderAdditionalHttpHeader(httpHeaders);
   }
 
   /**
    * Hook to override in subclasses to add additional HTTP headers.
    *
    * @param httpHeaders the headers to add to.
    */
   protected void renderAdditionalHttpHeader(
       final MultivaluedMap<String, Object> httpHeaders)
   {
   }
 
   /**
    * Renders a link in the HTTP header.
    *
    * @param httpHeaders the headers to add to.
    * @param link the link to add.
    */
   protected final void renderHttpHeaderLink(
       final MultivaluedMap<String, Object> httpHeaders,
       final LinkDescriptor link)
   {
     // TODO: Add additional properties of link if present
     final String rel = link.getRel();
     final String href = link.getHref();
 
     final String header = "<" + href + ">; rel=\"" + rel + '"';
     httpHeaders.add("Link", header);
   }
 
   /**
    * Redners the HTTP body.
    */
   protected abstract void httpBody();
 
   /**
    * Releases any resources held by the renderer.
    */
   protected abstract void close();
 
   // --- object basics --------------------------------------------------------
 
 }