/*
    * 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 org.esigate.esi;
  
  import java.io.IOException;
  import java.io.Writer;
  import java.util.Map;
  import java.util.regex.Pattern;
  
  import org.apache.http.HttpStatus;
  import org.esigate.HttpErrorPage;
  import org.esigate.Parameters;
  import org.esigate.Renderer;
  import org.esigate.impl.DriverRequest;
  import org.esigate.parser.Parser;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * Retrieves a resource from the provider application and parses it to find ESI tags to be replaced by contents from
   * other applications.
   * 
   * For more information about ESI language specification, see <a href="http://www.w3.org/TR/esi-lang">Edge Side
   * Include</a>
   * 
   * @author Francois-Xavier Bonnet
   */
  public class EsiRenderer implements Renderer, Appendable {
  
      private static final Logger LOG = LoggerFactory.getLogger(EsiRenderer.class);
  
      private static final Pattern PATTERN = Pattern
              .compile("(<esi:\\w+((\\s+\\w+(\\s*=\\s*(?:\".*?\"|'.*?'|[^'\">\\s]+))?)+\\s*|\\s*)/?>)|(</esi:[^>]*>)");
      private static final Pattern PATTERN_COMMENTS = Pattern.compile("(<!--esi)|(-->)");
  
      private final Parser parser = new Parser(PATTERN, IncludeElement.TYPE, CommentElement.TYPE, RemoveElement.TYPE,
              VarsElement.TYPE, ChooseElement.TYPE, WhenElement.TYPE, OtherwiseElement.TYPE, TryElement.TYPE,
              AttemptElement.TYPE, ExceptElement.TYPE, InlineElement.TYPE, ReplaceElement.TYPE, FragmentElement.TYPE);
  
      private final Parser parserComments = new Parser(PATTERN_COMMENTS, Comment.TYPE);
  
      private Writer out;
  
      private Map<String, CharSequence> fragmentsToReplace;
  
      private final String page;
  
      private final String name;
  
      private boolean write = true;
  
      private boolean found = false;
  
      public String getName() {
          return name;
      }
  
      public void setWrite(boolean write) {
          this.write = write;
      }
  
      /**
       * Constructor used to render a complete page.
       */
      public EsiRenderer() {
          page = null;
          name = null;
      }
  
      /**
       * Constructor used to render a fragment Retrieves a fragment inside a page.<br>
       * 
       * Extracts html between <code>&lt;esi:fragment name="myFragment"&gt;</code> and <code>&lt;/esi:fragment&gt;</code>
       * 
       * @param page
       * @param name
       */
      public EsiRenderer(String page, String name) {
          this.page = page;
          this.name = name;
          write = false;
      }
  
      public Map<String, CharSequence> getFragmentsToReplace() {
          return fragmentsToReplace;
      }
  
     public void setFragmentsToReplace(Map<String, CharSequence> fragmentsToReplace) {
         this.fragmentsToReplace = fragmentsToReplace;
     }
 
     @Override
     public void render(DriverRequest originalRequest, String content, Writer outWriter) throws IOException,
             HttpErrorPage {
         if (name != null) {
             LOG.debug("Rendering fragment {} in page {}", name, page);
         }
         this.out = outWriter;
         if (content == null) {
             return;
         }
 
         // Pass 1. Remove esi comments
         StringBuilder contentWithoutComments = new StringBuilder(Parameters.DEFAULT_BUFFER_SIZE);
         parserComments.setHttpRequest(originalRequest);
         parserComments.parse(content, contentWithoutComments);
 
         // Pass 2. Process ESI
         parser.setHttpRequest(originalRequest);
         parser.parse(contentWithoutComments, this);
 
         if (name != null && !this.found) {
             throw new HttpErrorPage(HttpStatus.SC_BAD_GATEWAY, "Fragment " + name + " not found", "Fragment " + name
                     + " not found");
         }
     }
 
     @Override
     public Appendable append(CharSequence csq) throws IOException {
         if (write) {
             out.append(csq);
         }
         return this;
     }
 
     @Override
     public Appendable append(char c) throws IOException {
         if (write) {
             out.append(c);
         }
         return this;
     }
 
     @Override
     public Appendable append(CharSequence csq, int start, int end) throws IOException {
         if (write) {
             out.append(csq, start, end);
         }
         return this;
     }
 
     public boolean isWrite() {
         return this.write;
     }
 
     public void setFound(boolean found) {
         this.found = found;
 
     }
 
 }