/*
    * 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.commons.monitoring.web.servlet;
  
  import org.apache.commons.monitoring.Role;
  import org.apache.commons.monitoring.counters.Counter;
  import org.apache.commons.monitoring.repositories.Repository;
  import org.apache.commons.monitoring.stopwatches.StopWatch;
  
  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.HttpServletRequest;
  import javax.servlet.http.HttpServletResponse;
  import java.io.IOException;
  
  public class MonitoringFilter implements Filter {
      @Override
      public void init(final FilterConfig filterConfig) throws ServletException {
          // no-op
      }
  
      @Override
      public void doFilter(final ServletRequest request, final ServletResponse response, final FilterChain chain) throws IOException, ServletException {
          if (HttpServletRequest.class.isInstance(request)) {
              final HttpServletRequest httpRequest = HttpServletRequest.class.cast(request);
              final HttpServletResponse httpResponse = HttpServletResponse.class.cast(response);
              doFilter(httpRequest, httpResponse, chain);
          } else {
              // Not an HTTP request...
              chain.doFilter(request, response);
          }
      }
  
      @Override
      public void destroy() {
          // no-op
      }
  
      protected void doFilter(final HttpServletRequest request, final HttpServletResponse response, final FilterChain chain) throws IOException, ServletException {
          final String uri = getRequestedUri(request);
          final StopWatch stopWatch = Repository.INSTANCE.start(Repository.INSTANCE.getCounter(new Counter.Key(Role.WEB, uri)));
          try {
              chain.doFilter(request, response);
          } finally {
              stopWatch.stop();
          }
      }
  
      protected String getRequestedUri(final HttpServletRequest request) {
          final String uri = request.getRequestURI();
          final String context = request.getContextPath();
          return uri.substring(context.length());
      }
  }