/* Copyright 2004, 2005, 2006 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.springframework.security.providers.anonymous;
  
  import org.springframework.security.Authentication;
  
  import org.springframework.security.context.SecurityContextHolder;
  
  import org.springframework.security.ui.AuthenticationDetailsSource;
  import org.springframework.security.ui.WebAuthenticationDetailsSource;
  import org.springframework.security.ui.FilterChainOrder;
  import org.springframework.security.ui.SpringSecurityFilter;
  import org.springframework.security.userdetails.memory.UserAttribute;
  import org.springframework.beans.factory.InitializingBean;
  import org.springframework.util.Assert;
  
  import java.io.IOException;
  
  import javax.servlet.FilterChain;
  import javax.servlet.ServletException;
  import javax.servlet.http.HttpServletRequest;
  import javax.servlet.http.HttpServletResponse;
  
  
  /**
   * Detects if there is no <code>Authentication</code> object in the <code>SecurityContextHolder</code>,  and
   * populates it with one if needed.
   *
   * @author Ben Alex
   * @version $Id: AnonymousProcessingFilter.java 2800 2008-03-25 14:51:34Z luke_t $
   */
  public class AnonymousProcessingFilter  extends SpringSecurityFilter  implements InitializingBean {
  
      //~ Instance fields ================================================================================================
  
      private AuthenticationDetailsSource authenticationDetailsSource = new WebAuthenticationDetailsSource();
      private String key;
      private UserAttribute userAttribute;
      private boolean removeAfterRequest = true;
  
      //~ Methods ========================================================================================================
  
      public void afterPropertiesSet() throws Exception {
          Assert.notNull(userAttribute);
          Assert.hasLength(key);
      }
  
      /**
       * Enables subclasses to determine whether or not an anonymous authentication token should be setup for
       * this request. This is useful if anonymous authentication should be allowed only for specific IP subnet ranges
       * etc.
       *
       * @param request to assist the method determine request details
       *
       * @return <code>true</code> if the anonymous token should be setup for this request (provided that the request
       *         doesn't already have some other <code>Authentication</code> inside it), or <code>false</code> if no
       *         anonymous token should be setup for this request
       */
      protected boolean applyAnonymousForThisRequest(HttpServletRequest request) {
          return true;
      }
  
      protected Authentication createAuthentication(HttpServletRequest request) {
          AnonymousAuthenticationToken auth = new AnonymousAuthenticationToken(key, userAttribute.getPassword(),
                  userAttribute.getAuthorities());
          auth.setDetails(authenticationDetailsSource.buildDetails((HttpServletRequest) request));
  
          return auth;
      }
  
      protected void doFilterHttp(HttpServletRequest request,HttpServletResponse response, FilterChain chain) throws IOException, ServletException {
          boolean addedToken = false;
  
          if (applyAnonymousForThisRequest(request)) {
              if (SecurityContextHolder.getContext().getAuthentication() == null) {
                  SecurityContextHolder.getContext().setAuthentication(createAuthentication(request));
                  addedToken = true;
  
                  if (logger.isDebugEnabled()) {
                      logger.debug("Populated SecurityContextHolder with anonymous token: '"
                          + SecurityContextHolder.getContext().getAuthentication() + "'");
                  }
              } else {
                  if (logger.isDebugEnabled()) {
                      logger.debug("SecurityContextHolder not populated with anonymous token, as it already contained: '"
                          + SecurityContextHolder.getContext().getAuthentication() + "'");
                 }
             }
         }
 
         try {
             chain.doFilter(request, response);
         } finally {
             if (addedToken && removeAfterRequest
                 && createAuthentication(request).equals(SecurityContextHolder.getContext().getAuthentication())) {
                 SecurityContextHolder.getContext().setAuthentication(null);
             }
         }
     }
 
     public int getOrder() {
         return FilterChainOrder.ANONYMOUS_FILTER;
     }
 
     public String getKey() {
         return key;
     }
 
     public UserAttribute getUserAttribute() {
         return userAttribute;
     }
 
     public boolean isRemoveAfterRequest() {
         return removeAfterRequest;
     }
 
     public void setAuthenticationDetailsSource(AuthenticationDetailsSource authenticationDetailsSource) {
         Assert.notNull(authenticationDetailsSource, "AuthenticationDetailsSource required");
         this.authenticationDetailsSource = authenticationDetailsSource;
     }
 
     public void setKey(String key) {
         this.key = key;
     }
 
     /**
      * Controls whether the filter will remove the Anonymous token after the request is complete. Generally
      * this is desired to avoid the expense of a session being created by {@link
      * org.springframework.security.context.HttpSessionContextIntegrationFilter HttpSessionContextIntegrationFilter} simply to
      * store the Anonymous authentication token.<p>Defaults to <code>true</code>, being the most optimal and
      * appropriate option (ie <code>AnonymousProcessingFilter</code> will clear the token at the end of each request,
      * thus avoiding the session creation overhead in a typical configuration.</p>
      *
      * @param removeAfterRequest DOCUMENT ME!
      */
     public void setRemoveAfterRequest(boolean removeAfterRequest) {
         this.removeAfterRequest = removeAfterRequest;
     }
 
     public void setUserAttribute(UserAttribute userAttributeDefinition) {
         this.userAttribute = userAttributeDefinition;
     }
 }