/*
 * 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.hdds.server.http;

import java.io.IOException;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletResponse;

/**
 * Servlet filter to add no caching headers.
 */
public class NoCacheFilter implements Filter {

  @Override
  public void init(FilterConfig filterConfig) throws ServletException {
  }

  @Override
  public void doFilter(ServletRequest req, ServletResponse res,
      FilterChain chain)
      throws IOException, ServletException {
    HttpServletResponse httpRes = (HttpServletResponse) res;
    httpRes.setHeader("Cache-Control", "no-cache");
    long now = System.currentTimeMillis();
    httpRes.setDateHeader("Expires", now);
    httpRes.setDateHeader("Date", now);
    httpRes.setHeader("Pragma", "no-cache");
    chain.doFilter(req, res);
  }

  @Override
  public void destroy() {
  }

}
