/*
    * 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 java.io.IOException;
  import java.text.DecimalFormat;
  import java.util.Enumeration;
  
  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 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;
  
  /**
   * Filter to initialize and clear the RequestContext.
   */
  public class RequestContextFilter implements Filter {
  
      private static final Logger logger = LogManager.getLogger(RequestContextFilter.class);
      private final Class<?> requestContextClass;
      private RequestContextMappings mappings;
  
      public RequestContextFilter() {
          requestContextClass = null;
      }
  
      public RequestContextFilter(Class<?> clazz) {
          requestContextClass = clazz;
      }
  
      /**
       * @param filterConfig
       * @throws ServletException
       */
      @Override
      public void init(FilterConfig filterConfig) throws ServletException {
          if (requestContextClass != null) {
              mappings = new RequestContextMappings(requestContextClass);
          } else {
              String requestContextClassName = filterConfig.getInitParameter("requestContextClass");
              if (requestContextClassName == null) {
                  logger.error("No RequestContext class name was provided");
                  throw new IllegalArgumentException("No RequestContext class name provided");
              }
              mappings = new RequestContextMappings(requestContextClassName);
          }
      }
  
      /**
       * Manages the initialization and clearing of the RequestContext.
       */
      public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain)
              throws IOException, ServletException {
          if (servletRequest instanceof HttpServletRequest) {
              HttpServletRequest request = (HttpServletRequest) servletRequest;
              HttpServletResponse response = (HttpServletResponse) servletResponse;
              logger.trace("Starting request {}", request.getRequestURI());
              try {
                  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));
                          }
                     }
                 }
                 long start = 0;
                 if (logger.isTraceEnabled()) {
                     start = System.nanoTime();
                 }
                 filterChain.doFilter(servletRequest, servletResponse);
                 if (logger.isTraceEnabled()) {
                     long elapsed = System.nanoTime() - start;
                     StringBuilder sb = new StringBuilder("Request ").append(request.getRequestURI()).append(" completed in ");
                     ElapsedUtil.addElapsed(elapsed, sb);
                     logger.trace(sb.toString());
                 }
             } catch (Throwable e) {
                 logger.error("Application cascaded error", e);
                 response.setStatus(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
             } finally {
                 ThreadContext.clearMap();
             }
         }
     }
 
     public void destroy() {
     }
 }