/* Copyright 2004, 2005 Acegi Technology Pty Limited
    *
    * Licensed 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.acegisecurity.adapters.jboss;
  
  import org.acegisecurity.Authentication;
  import org.acegisecurity.context.SecurityContextHolder;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  
  import java.io.IOException;
  
  import java.security.Principal;
  
  import java.util.Iterator;
  
  import javax.naming.Context;
  import javax.naming.InitialContext;
  import javax.naming.NamingException;
  
  import javax.security.auth.Subject;
  
  import javax.servlet.Filter;
  import javax.servlet.FilterChain;
  import javax.servlet.FilterConfig;
  import javax.servlet.ServletException;
  import javax.servlet.ServletRequest;
  import javax.servlet.ServletResponse;
  
  
  /***
   * Populates a {@link org.acegisecurity.context.security.SecureContext} from
   * JBoss' <code>java:comp/env/security/subject</code>.
   * 
   * <p>
   * This filter <b>never</b> preserves the <code>Authentication</code> on the
   * <code>ContextHolder</code> - it is replaced every request.
   * </p>
   * 
   * <p>
   * See {@link HttpSessionContextIntegrationFilter} for further information.
   * </p>
   *
   * @author Ben Alex
   * @version $Id: JbossIntegrationFilter.java,v 1.11 2005/11/17 00:56:29 benalex Exp $
   */
  public class JbossIntegrationFilter implements Filter {
      //~ Static fields/initializers =============================================
  
      private static final Log logger = LogFactory.getLog(JbossIntegrationFilter.class);
  
      //~ Methods ================================================================
  
      /***
       * Does nothing. We use IoC container lifecycle services instead.
       */
      public void destroy() {}
  
      public void doFilter(ServletRequest request, ServletResponse response,
          FilterChain chain) throws IOException, ServletException {
          Object principal = extractFromContainer(request);
  
          if ((principal != null) && principal instanceof Authentication) {
              SecurityContextHolder.getContext().setAuthentication((Authentication) principal);
  
              if (logger.isDebugEnabled()) {
                  logger.debug(
                      "ContextHolder updated with Authentication from container: '"
                      + principal + "'");
              }
          } else {
              if (logger.isDebugEnabled()) {
                  logger.debug(
                      "ContextHolder not set with new Authentication as Principal was: '"
                      + principal + "'");
              }
          }
  
          chain.doFilter(request, response);
      }
  
      /***
       * Does nothing. We use IoC container lifecycle services instead.
       *
       * @param arg0 ignored
       *
      * @throws ServletException ignored
      */
     public void init(FilterConfig arg0) throws ServletException {}
 
     /***
      * Provided so that unit tests can override.
      *
      * @return a <code>Context</code> that can be used for lookup
      *
      * @throws NamingException DOCUMENT ME!
      */
     protected Context getLookupContext() throws NamingException {
         return new InitialContext();
     }
 
     private Object extractFromContainer(ServletRequest request) {
         Subject subject = null;
 
         try {
             Context lc = this.getLookupContext();
 
             if (lc == null) {
                 if (logger.isWarnEnabled()) {
                     logger.warn("Could not obtain a Context to perform lookup");
                 }
 
                 return null;
             }
 
             Object result = lc.lookup("java:comp/env/security/subject");
 
             if (result instanceof Subject) {
                 subject = (Subject) result;
             }
         } catch (NamingException ne) {
             if (logger.isWarnEnabled()) {
                 logger.warn("Lookup on Subject failed "
                     + ne.getLocalizedMessage());
             }
         }
 
         if ((subject != null) && (subject.getPrincipals() != null)) {
             Iterator principals = subject.getPrincipals().iterator();
 
             while (principals.hasNext()) {
                 Principal p = (Principal) principals.next();
 
                 if (p instanceof Authentication) {
                     return p;
                 }
             }
         }
 
         return null;
     }
 }