/*
 * @(#)ContentEncodingModule.java             0.3-3 06/05/2001
 *
 *  This file is part of the HTTPClient package
 *  Copyright (C) 1996-2001 Ronald Tschal�r
 *
 *  This library is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Lesser General Public
 *  License as published by the Free Software Foundation; either
 *  version 2 of the License, or (at your option) any later version.
 *
 *  This library is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public
 *  License along with this library; if not, write to the Free
 *  Software Foundation, Inc., 59 Temple Place, Suite 330, Boston,
 *  MA 02111-1307, USA
 *
 *  For questions, suggestions, bug-reports, enhancement-requests etc.
 *  I may be contacted at:
 *
 *  ronald@innovation.ch
 *
 *  The HTTPClient's home page is located at:
 *
 *  http://www.innovation.ch/java/HTTPClient/ 
 *
 */

package org.exoplatform.common.http.client;

import org.exoplatform.services.log.ExoLogger;
import org.exoplatform.services.log.Log;

import java.io.IOException;
import java.util.Vector;
import java.util.zip.GZIPInputStream;
import java.util.zip.InflaterInputStream;

/**
 * This module handles the Content-Encoding response header. It currently
 * handles the "gzip", "deflate", "compress" and "identity" tokens.
 * @version 0.3-3 06/05/2001
 * @author Ronald Tschal�r
 */
class ContentEncodingModule implements HTTPClientModule
{

   private static final Log LOG = ExoLogger.getLogger("exo.ws.commons.ContentEncodingModule");

   // Methods

   /**
    * Invoked by the HTTPClient.
    */
   public int requestHandler(Request req, Response[] resp) throws ModuleException
   {
      // parse Accept-Encoding header

      int idx;
      NVPair[] hdrs = req.getHeaders();
      for (idx = 0; idx < hdrs.length; idx++)
         if (hdrs[idx].getName().equalsIgnoreCase("Accept-Encoding"))
            break;

      Vector pae;
      if (idx == hdrs.length)
      {
         hdrs = Util.resizeArray(hdrs, idx + 1);
         req.setHeaders(hdrs);
         pae = new Vector();
      }
      else
      {
         try
         {
            pae = Util.parseHeader(hdrs[idx].getValue());
         }
         catch (ParseException pe)
         {
            throw new ModuleException(pe.toString());
         }
      }

      // done if "*;q=1.0" present

      HttpHeaderElement all = Util.getElement(pae, "*");
      if (all != null)
      {
         NVPair[] params = all.getParams();
         for (idx = 0; idx < params.length; idx++)
            if (params[idx].getName().equalsIgnoreCase("q"))
               break;

         if (idx == params.length) // no qvalue, i.e. q=1.0
            return REQ_CONTINUE;

         if (params[idx].getValue() == null || params[idx].getValue().length() == 0)
            throw new ModuleException("Invalid q value for \"*\" in " + "Accept-Encoding header: ");

         try
         {
            if (Float.valueOf(params[idx].getValue()).floatValue() > 0.)
               return REQ_CONTINUE;
         }
         catch (NumberFormatException nfe)
         {
            throw new ModuleException("Invalid q value for \"*\" in " + "Accept-Encoding header: " + nfe.getMessage());
         }
      }

      // Add gzip, deflate and compress tokens to the Accept-Encoding header

      if (!pae.contains(new HttpHeaderElement("deflate")))
         pae.addElement(new HttpHeaderElement("deflate"));
      if (!pae.contains(new HttpHeaderElement("gzip")))
         pae.addElement(new HttpHeaderElement("gzip"));
      if (!pae.contains(new HttpHeaderElement("x-gzip")))
         pae.addElement(new HttpHeaderElement("x-gzip"));
      if (!pae.contains(new HttpHeaderElement("compress")))
         pae.addElement(new HttpHeaderElement("compress"));
      if (!pae.contains(new HttpHeaderElement("x-compress")))
         pae.addElement(new HttpHeaderElement("x-compress"));

      hdrs[idx] = new NVPair("Accept-Encoding", Util.assembleHeader(pae));

      return REQ_CONTINUE;
   }

   /**
    * Invoked by the HTTPClient.
    */
   public void responsePhase1Handler(Response resp, RoRequest req)
   {
   }

   /**
    * Invoked by the HTTPClient.
    */
   public int responsePhase2Handler(Response resp, Request req)
   {
      return RSP_CONTINUE;
   }

   /**
    * Invoked by the HTTPClient.
    */
   public void responsePhase3Handler(Response resp, RoRequest req) throws IOException, ModuleException
   {
      String ce = resp.getHeader("Content-Encoding");
      if (ce == null || req.getMethod().equals("HEAD") || resp.getStatusCode() == 206)
         return;

      Vector pce;
      try
      {
         pce = Util.parseHeader(ce);
      }
      catch (ParseException pe)
      {
         throw new ModuleException(pe.toString());
      }

      if (pce.size() == 0)
         return;

      String encoding = ((HttpHeaderElement)pce.firstElement()).getName();
      if (encoding.equalsIgnoreCase("gzip") || encoding.equalsIgnoreCase("x-gzip"))
      {
         if (LOG.isDebugEnabled())
            LOG.debug("Pushing gzip-input-stream");

         resp.inp_stream = new GZIPInputStream(resp.inp_stream);
         pce.removeElementAt(pce.size() - 1);
         resp.deleteHeader("Content-length");
      }
      else if (encoding.equalsIgnoreCase("deflate"))
      {
         if (LOG.isDebugEnabled())
            LOG.debug("Pushing inflater-input-stream");

         resp.inp_stream = new InflaterInputStream(resp.inp_stream);
         pce.removeElementAt(pce.size() - 1);
         resp.deleteHeader("Content-length");
      }
      else if (encoding.equalsIgnoreCase("compress") || encoding.equalsIgnoreCase("x-compress"))
      {
         if (LOG.isDebugEnabled())
            LOG.debug("Pushing uncompress-input-stream");

         resp.inp_stream = new UncompressInputStream(resp.inp_stream);
         pce.removeElementAt(pce.size() - 1);
         resp.deleteHeader("Content-length");
      }
      else if (encoding.equalsIgnoreCase("identity"))
      {
         if (LOG.isDebugEnabled())
            LOG.debug("Ignoring 'identity' token");

         pce.removeElementAt(pce.size() - 1);
      }
      else
      {
         if (LOG.isDebugEnabled())
            LOG.debug("Unknown content encoding '" + encoding + "'");

      }

      if (pce.size() > 0)
         resp.setHeader("Content-Encoding", Util.assembleHeader(pce));
      else
         resp.deleteHeader("Content-Encoding");
   }

   /**
    * Invoked by the HTTPClient.
    */
   public void trailerHandler(Response resp, RoRequest req)
   {
   }
}
