/* 
    * 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.tags;
  
  import java.io.IOException;
  import java.io.Writer;
  import java.util.Map;
  import java.util.regex.Pattern;
  
  import org.esigate.HttpErrorPage;
  import org.esigate.Renderer;
  import org.esigate.impl.DriverRequest;
  import org.esigate.parser.Parser;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * Template renderer.
   * <p>
   * Retrieves a template from the provider application and renders it to the writer replacing the parameters with the
   * given map. If <code>name</code> param is <code>null</code>, the whole page will be used as the template.<br>
   * eg: The template <code>mytemplate</code> can be delimited in the provider page by comments
   * <code>&lt;!--$begintemplate$mytemplate$--&gt;</code> and <code>&lt;!--$endtemplate$mytemplate$--&gt;</code>.<br>
   * Inside the template, the parameters can be defined by comments.<br>
   * eg: parameter named <code>myparam</code> should be delimited by comments
   * <code>&lt;!--$beginparam$myparam$--&gt;</code> and <code>&lt;!--$endparam$myparam$--&gt;</code>
   * 
   * @author Stanislav Bernatskyi
   * @author Francois-Xavier Bonnet
   */
  public class TemplateRenderer implements Renderer, Appendable {
      private static final Logger LOG = LoggerFactory.getLogger(TemplateRenderer.class);
      private static final Pattern PATTERN = Pattern.compile("<!--\\$[^>]*\\$-->");
  
      private final Parser parser = new Parser(PATTERN, TemplateElement.TYPE, ParamElement.TYPE);
      private final String page;
      private final String name;
      private final Map<String, String> params;
      private boolean write;
      private Writer out;
  
      public TemplateRenderer(String name, Map<String, String> params, String page) {
          this.name = name;
          this.params = params;
          this.page = page;
          if (name == null) {
              write = true;
          }
      }
  
      /** {@inheritDoc} */
      @Override
      public void render(DriverRequest httpRequest, String content, Writer pOut) throws IOException, HttpErrorPage {
          LOG.debug("Rendering block " + name + " in page " + page);
          this.out = pOut;
          if (content == null) {
              if (params != null) {
                  for (String value : params.values()) {
                      out.write(value);
                  }
              }
          } else {
              parser.parse(content, this);
          }
      }
  
      public String getName() {
          return name;
      }
  
      public void setWrite(boolean write) {
          this.write = write;
      }
  
      public String getParam(String pName) {
          return params.get(pName);
      }
  
      @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;
     }
 
 }