/**
    * This file Copyright (c) 2010-2015 Magnolia International
    * Ltd.  (http://www.magnolia-cms.com). All rights reserved.
    *
    *
    * This file is dual-licensed under both the Magnolia
    * Network Agreement and the GNU General Public License.
    * You may elect to use one or the other of these licenses.
    *
   * This file is distributed in the hope that it will be
   * useful, but AS-IS and WITHOUT ANY WARRANTY; without even the
   * implied warranty of MERCHANTABILITY or FITNESS FOR A
   * PARTICULAR PURPOSE, TITLE, or NONINFRINGEMENT.
   * Redistribution, except as permitted by whichever of the GPL
   * or MNA you select, is prohibited.
   *
   * 1. For the GPL license (GPL), you can redistribute and/or
   * modify this file under the terms of the GNU General
   * Public License, Version 3, as published by the Free Software
   * Foundation.  You should have received a copy of the GNU
   * General Public License, Version 3 along with this program;
   * if not, write to the Free Software Foundation, Inc., 51
   * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
   *
   * 2. For the Magnolia Network Agreement (MNA), this file
   * and the accompanying materials are made available under the
   * terms of the MNA which accompanies this distribution, and
   * is available at http://www.magnolia-cms.com/mna.html
   *
   * Any modifications to this file must keep this entire header
   * intact.
   *
   */
  package info.magnolia.module.cache.filter;
  
  import java.io.File;
  import java.io.FileInputStream;
  import java.io.IOException;
  
  import javax.servlet.FilterChain;
  import javax.servlet.ServletException;
  import javax.servlet.http.HttpServletRequest;
  import javax.servlet.http.HttpServletResponse;
  
  import org.apache.commons.collections.MultiMap;
  import org.apache.commons.io.FileUtils;
  import org.apache.commons.io.IOUtils;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  
  /**
   * Used for large responses. Typically we don't want to cache big responses as they are so costly to keep in memory and
   * tend to evict so much from the cache where they're put in that net performance drops. This cache entry does not keep
   * the response in memory, instead it serves it from a file on disk or if there's no file it proceeds with rendering.
   * When it has used the file once it deletes it. The entry still remains in cache and serves as a token to prevent
   * caching in the future.
   *
   * The file is created by {@link CacheResponseWrapper} when it reaches its set threshold.
   *
   * @version $Id$
   * @see CacheResponseWrapper
   */
  public class DelegatingBlobCachedEntry extends ContentCachedEntry {
  
      private static Logger log = LoggerFactory.getLogger(DelegatingBlobCachedEntry.class);
  
  
      public static final String CONTENT_FILE_ATTRIBUTE = DelegatingBlobCachedEntry.class.getName() + ".contentFile";
  
      private final long contentLength;
  
      public DelegatingBlobCachedEntry(long contentLength, String contentType, String characterEncoding, int statusCode, MultiMap headers, long modificationDate, String originalUrl, int timeToLiveInSeconds) throws IOException {
          super(contentType, characterEncoding, statusCode, headers, modificationDate, originalUrl, timeToLiveInSeconds);
          this.contentLength = contentLength;
      }
  
      @Override
      protected boolean canServeGzipContent() {
          return false;
      }
  
      @Override
      public void replay(HttpServletRequest request, HttpServletResponse response, FilterChain chain) throws IOException, ServletException {
          File contentFile = getContentFileBoundToTheRequest(request);
          if(contentFile != null){
              log.debug("About to serve response from {}", contentFile.getAbsolutePath());
              super.replay(request, response, chain);
          }
          else{
              chain.doFilter(request, response);
          }
      }
  
      @Override
      protected void writeContent(HttpServletRequest request, HttpServletResponse response, FilterChain chain, boolean acceptsGzipEncoding) throws IOException, ServletException {
          response.setContentLength((int) contentLength);
  
          File contentFile = getContentFileBoundToTheRequest(request);
         if(contentFile != null){
             log.debug("Streaming out output from {}", contentFile.getAbsolutePath());
             FileInputStream contentStream = FileUtils.openInputStream(contentFile);
             try{
                 IOUtils.copy(contentStream,response.getOutputStream());
             }finally{
                 IOUtils.closeQuietly(contentStream);
                 log.debug("About to delete temp file {}", contentFile.getAbsolutePath());
                 if(!contentFile.delete()){
                     log.error("Can't delete file: " + contentFile);
                 }
             }
         }
         else{
             // should not happen as we delegate to the filter chain in replay in that case and ignore all cached data
             throw new IllegalStateException("No content file attached to the request!");
         }
     }
 
     private File getContentFileBoundToTheRequest(HttpServletRequest request) {
         return (File) request.getAttribute(CONTENT_FILE_ATTRIBUTE);
     }
 
     public void bindContentFileToCurrentRequest(HttpServletRequest request, File contentFile){
         request.setAttribute(DelegatingBlobCachedEntry.CONTENT_FILE_ATTRIBUTE, contentFile);
     }
 
 }