/* 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.acegisecurity.securechannel;
  
  import org.acegisecurity.ConfigAttribute;
  import org.acegisecurity.ConfigAttributeDefinition;
  
  import org.acegisecurity.intercept.web.FilterInvocation;
  import org.acegisecurity.intercept.web.FilterInvocationDefinitionSource;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  
  import org.springframework.beans.factory.InitializingBean;
  
  import org.springframework.util.Assert;
  
  import java.io.IOException;
  
  import java.util.HashSet;
  import java.util.Iterator;
  import java.util.Set;
  
  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;
  
  
  /**
   * Ensures a web request is delivered over the required channel.<p>Internally uses a {@link FilterInvocation} to
   * represent the request, so that the <code>FilterInvocation</code>-related property editors and lookup classes can be
   * used.</p>
   *  <P>Delegates the actual channel security decisions and necessary actions to the configured {@link
   * ChannelDecisionManager}. If a response is committed by the <code>ChannelDecisionManager</code>, the filter chain
   * will not proceed.</p>
   *  <P><B>Do not use this class directly.</B> Instead configure <code>web.xml</code> to use the {@link
   * org.acegisecurity.util.FilterToBeanProxy}.</p>
   *
   * @author Ben Alex
   * @version $Id: ChannelProcessingFilter.java 1784 2007-02-24 21:00:24Z luke_t $
   */
  public class ChannelProcessingFilter implements InitializingBean, Filter {
      //~ Static fields/initializers =====================================================================================
  
      private static final Log logger = LogFactory.getLog(ChannelProcessingFilter.class);
  
      //~ Instance fields ================================================================================================
  
      private ChannelDecisionManager channelDecisionManager;
      private FilterInvocationDefinitionSource filterInvocationDefinitionSource;
  
      //~ Methods ========================================================================================================
  
      public void afterPropertiesSet() throws Exception {
          Assert.notNull(filterInvocationDefinitionSource, "filterInvocationDefinitionSource must be specified");
          Assert.notNull(channelDecisionManager, "channelDecisionManager must be specified");
  
          Iterator iter = this.filterInvocationDefinitionSource.getConfigAttributeDefinitions();
  
          if (iter == null) {
              if (logger.isWarnEnabled()) {
                  logger.warn("Could not validate configuration attributes as the FilterInvocationDefinitionSource did "
                          + "not return a ConfigAttributeDefinition Iterator");
              }
  
              return;
          }
  
          Set set = new HashSet();
  
          while (iter.hasNext()) {
              ConfigAttributeDefinition def = (ConfigAttributeDefinition) iter.next();
              Iterator attributes = def.getConfigAttributes();
  
              while (attributes.hasNext()) {
                  ConfigAttribute attr = (ConfigAttribute) attributes.next();
  
                  if (!this.channelDecisionManager.supports(attr)) {
                      set.add(attr);
                  }
              }
         }
 
         if (set.size() == 0) {
             if (logger.isInfoEnabled()) {
                 logger.info("Validated configuration attributes");
             }
         } else {
             throw new IllegalArgumentException("Unsupported configuration attributes: " + set.toString());
         }
     }
 
     public void destroy() {}
 
     public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
         throws IOException, ServletException {
         if (!(request instanceof HttpServletRequest)) {
             throw new ServletException("HttpServletRequest required");
         }
 
         if (!(response instanceof HttpServletResponse)) {
             throw new ServletException("HttpServletResponse required");
         }
 
         FilterInvocation fi = new FilterInvocation(request, response, chain);
         ConfigAttributeDefinition attr = this.filterInvocationDefinitionSource.getAttributes(fi);
 
         if (attr != null) {
             if (logger.isDebugEnabled()) {
                 logger.debug("Request: " + fi.toString() + "; ConfigAttributes: " + attr.toString());
             }
 
             channelDecisionManager.decide(fi, attr);
 
             if (fi.getResponse().isCommitted()) {
                 return;
             }
         }
 
         chain.doFilter(request, response);
     }
 
     public ChannelDecisionManager getChannelDecisionManager() {
         return channelDecisionManager;
     }
 
     public FilterInvocationDefinitionSource getFilterInvocationDefinitionSource() {
         return filterInvocationDefinitionSource;
     }
 
     public void init(FilterConfig filterConfig) throws ServletException {}
 
     public void setChannelDecisionManager(ChannelDecisionManager channelDecisionManager) {
         this.channelDecisionManager = channelDecisionManager;
     }
 
     public void setFilterInvocationDefinitionSource(FilterInvocationDefinitionSource filterInvocationDefinitionSource) {
         this.filterInvocationDefinitionSource = filterInvocationDefinitionSource;
     }
 }