/*
    *
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF licenses this file
    * to you 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.apache.hadoop.hbase.rest.filter;
  
  import java.io.IOException;
  import java.io.PrintWriter;
  
  import javax.servlet.ServletOutputStream;
  import javax.servlet.http.HttpServletResponse;
  import javax.servlet.http.HttpServletResponseWrapper;
  
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  
  @InterfaceAudience.Private
  public class GZIPResponseWrapper extends HttpServletResponseWrapper {
    private HttpServletResponse response;
    private ServletOutputStream os;
    private PrintWriter writer;
    private boolean compress = true;
  
    public GZIPResponseWrapper(HttpServletResponse response) {
      super(response);
      this.response = response;
    }
  
    @Override
    public void setStatus(int status) {
      super.setStatus(status);
      if (status < 200 || status >= 300) {
        compress = false;
      }
    }
  
    @Override
    public void addHeader(String name, String value) {
      if (!"content-length".equalsIgnoreCase(name)) {
        super.addHeader(name, value);
      }
    }
  
    @Override
    public void setContentLength(int length) {
      // do nothing
    }
  
    @Override
    public void setIntHeader(String name, int value) {
      if (!"content-length".equalsIgnoreCase(name)) {
        super.setIntHeader(name, value);
      }
    }
  
    @Override
    public void setHeader(String name, String value) {
      if (!"content-length".equalsIgnoreCase(name)) {
        super.setHeader(name, value);
      }
    }
  
    @Override
    public void flushBuffer() throws IOException {
      if (writer != null) {
        writer.flush();
      }
      if (os != null && (os instanceof GZIPResponseStream)) {
        ((GZIPResponseStream)os).finish();
      } else {
        getResponse().flushBuffer();
      }
    }
  
    @Override
    public void reset() {
      super.reset();
      if (os != null && (os instanceof GZIPResponseStream)) {
        ((GZIPResponseStream)os).resetBuffer();
      }
      writer = null;
      os = null;
      compress = true;
    }
  
   @Override
   public void resetBuffer() {
     super.resetBuffer();
     if (os != null && (os instanceof GZIPResponseStream)) {
       ((GZIPResponseStream)os).resetBuffer();
     }
     writer = null;
     os = null;
   }
 
   @Override
   public void sendError(int status, String msg) throws IOException {
     resetBuffer();
     super.sendError(status, msg);
   }
 
   @Override
   public void sendError(int status) throws IOException {
     resetBuffer();
     super.sendError(status);
   }
 
   @Override
   public void sendRedirect(String location) throws IOException {
     resetBuffer();
     super.sendRedirect(location);
   }
 
   @Override
   public ServletOutputStream getOutputStream() throws IOException {
     if (os == null) {
       if (!response.isCommitted() && compress) {
         os = (ServletOutputStream)new GZIPResponseStream(response);
       } else {
         os = response.getOutputStream();
       }
     }
     return os;
   }
 
   @Override
   public PrintWriter getWriter() throws IOException {
     if (writer == null) {
       writer = new PrintWriter(getOutputStream());
     }
     return writer;
   }
 }