/*
    * Logback: the reliable, generic, fast and flexible logging framework.
    * Copyright (C) 1999-2026, QOS.ch. All rights reserved.
    *
    * This program and the accompanying materials are dual-licensed under
    * either the terms of the Eclipse Public License v2.0 as published by
    * the Eclipse Foundation
    *
    *   or (per the licensee's choosing)
   *
   * under the terms of the GNU Lesser General Public License version 2.1
   * as published by the Free Software Foundation.
   */
  package ch.qos.logback.classic.selector.servlet;
  
  import java.io.IOException;
  
  import jakarta.servlet.Filter;
  import jakarta.servlet.FilterChain;
  import jakarta.servlet.FilterConfig;
  import jakarta.servlet.ServletException;
  import jakarta.servlet.ServletRequest;
  import jakarta.servlet.ServletResponse;
  
  import org.slf4j.LoggerFactory;
  
  import ch.qos.logback.classic.LoggerContext;
  import ch.qos.logback.classic.selector.ContextJNDISelector;
  import ch.qos.logback.classic.selector.ContextSelector;
  import ch.qos.logback.classic.util.ContextSelectorStaticBinder;
  
  /**
   * A servlet filter that puts the environment-dependent LoggerContext in a
   * ThreadLocal variable, removing it after the request is processed.
   * 
   * <p>
   * To use it, add the following lines to a web.xml file
   * </p>
   * <pre>
    &lt;filter>
      &lt;filter-name>LoggerContextFilter&lt;/filter-name>
      &lt;filter-class>ch.qos.logback.classic.selector.servlet.LoggerContextFilter&lt;/filter-class>
   &lt;/filter>
  
   &lt;filter-mapping>
     &lt;filter-name>LoggerContextFilter&lt;/filter-name>
     &lt;url-pattern>/*&lt;/url-pattern>
   &lt;/filter-mapping>
   </pre>
   *
   * @author S&eacute;bastien Pennec
   */
  public class LoggerContextFilter implements Filter {
  
      public void destroy() {
          // do nothing
      }
  
      public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
              throws IOException, ServletException {
  
          LoggerContext lc = (LoggerContext) LoggerFactory.getILoggerFactory();
          ContextSelector selector = ContextSelectorStaticBinder.getSingleton().getContextSelector();
          ContextJNDISelector sel = null;
  
          if (selector instanceof ContextJNDISelector) {
              sel = (ContextJNDISelector) selector;
              sel.setLocalContext(lc);
          }
  
          try {
              chain.doFilter(request, response);
          } finally {
              if (sel != null) {
                  sel.removeLocalContext();
              }
          }
      }
  
      public void init(FilterConfig arg0) throws ServletException {
          // do nothing
      }
  }