/*
    * 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.logging.log4j.audit.rest;
  
  import javax.servlet.http.HttpServletRequest;
  import javax.servlet.http.HttpServletResponse;
  import java.util.Enumeration;
  
  import org.apache.logging.log4j.LogManager;
  import org.apache.logging.log4j.Logger;
  import org.apache.logging.log4j.ThreadContext;
  import org.apache.logging.log4j.audit.request.ChainedMapping;
  import org.apache.logging.log4j.audit.request.RequestContextMapping;
  import org.apache.logging.log4j.audit.request.RequestContextMappings;
  import org.springframework.web.servlet.HandlerInterceptor;
  import org.springframework.web.servlet.ModelAndView;
  
  /**
   * May be used instead of the RequestContextFilter to convert RequestContext headers to ThreadContext variables.
   */
  public class RequestContextHandlerInterceptor implements HandlerInterceptor {
  
      private static final Logger logger = LogManager.getLogger(RequestContextHandlerInterceptor.class);
      private RequestContextMappings mappings;
      private ThreadLocal<Long> startTime = new ThreadLocal<>();
  
      public RequestContextHandlerInterceptor(Class<?> clazz) {
          mappings = new RequestContextMappings(clazz);
      }
  
      @Override
      public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object o) throws Exception {
          logger.trace("Starting request {}", request.getRequestURI());
          Enumeration<String> headers = request.getHeaderNames();
          while (headers.hasMoreElements()) {
              String name = headers.nextElement();
              RequestContextMapping mapping = mappings.getMappingByHeader(name);
              logger.debug("Got Mapping:{} for Header:{}", mapping, name);
              if (mapping != null) {
                  if (mapping.isChained()) {
                      ThreadContext.put(mapping.getChainKey(), request.getHeader(name));
                      logger.debug("Setting Context Key:{} with value:{}", mapping.getChainKey(), request.getHeader(name));
                      String value = ((ChainedMapping) mapping).getSupplier().get();
                      ThreadContext.put(mapping.getFieldName(), value);
                      logger.debug("Setting Context Key:{} with value:{}", mapping.getFieldName(), value);
                  } else {
                      ThreadContext.put(mapping.getFieldName(), request.getHeader(name));
                      logger.debug("Setting Context Key:{} with value:{}", mapping.getFieldName(), request.getHeader(name));
                  }
              }
          }
          if (logger.isTraceEnabled()) {
              startTime.set(System.nanoTime());
          }
          return true;
      }
  
      @Override
      public void postHandle(HttpServletRequest request, HttpServletResponse response, Object o, ModelAndView modelAndView) throws Exception {
          if (logger.isTraceEnabled()) {
              long elapsed = System.nanoTime() - startTime.get();
              StringBuilder sb = new StringBuilder("Request ").append(request.getRequestURI()).append(" completed in ");
              ElapsedUtil.addElapsed(elapsed, sb);
              logger.trace(sb.toString());
              startTime.remove();
          }
      }
  
      @Override
      public void afterCompletion(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, Exception e) throws Exception {
          ThreadContext.clearMap();
      }
  }