/**
    * Copyright 2005-2012 The Kuali Foundation
    *
    * Licensed under the Educational Community 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.opensource.org/licenses/ecl2.php
    *
   * 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.kuali.rice.kim.client.acegi;
  
  import org.acegisecurity.Authentication;
  import org.acegisecurity.AuthenticationException;
  import org.acegisecurity.BadCredentialsException;
  import org.acegisecurity.providers.UsernamePasswordAuthenticationToken;
  import org.acegisecurity.providers.cas.CasAuthenticationProvider;
  import org.acegisecurity.providers.cas.CasAuthenticationToken;
  import org.acegisecurity.providers.cas.StatelessTicketCache;
  import org.acegisecurity.ui.cas.CasProcessingFilter;
  import org.acegisecurity.userdetails.UserDetails;
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  
  /**
   * A {@link CasAuthenticationProvider} implementation that integrates with 
   * Kuali Identity Management (KIM).<p>This 
   * <code>CasAuthenticationProvider</code> is capable of validating {@link
   * UsernamePasswordAuthenticationToken} requests which contains a 
   * distributed session token. It can also validate a previously created 
   * {@link CasAuthenticationToken}.</p>
   *
   * Verifies the the <code>UserDetails</code> based on a valid CAS ticket 
   * response.
   * 
   * @author Kuali Rice Team (rice.collab@kuali.org)
  */
  public class KualiCasAuthenticationProvider extends CasAuthenticationProvider {
      
      private static final Log logger = LogFactory.getLog(KualiCasAuthenticationProvider.class);
  
      /**
       * This overridden method is copied from CAS verbatim.  For some reason 
       * {@link authenticateNow} would not override and the super method 
       * would get called until did this method was also overridden.
       * 
       * @see org.acegisecurity.providers.cas.CasAuthenticationProvider#authenticate(org.acegisecurity.Authentication)
       */
      public Authentication authenticate(Authentication authentication) throws AuthenticationException {
          StatelessTicketCache statelessTicketCache = this.getStatelessTicketCache();
          String key = this.getKey();
          if (!supports(authentication.getClass())) {
              return null;
          }
  
          if (authentication instanceof UsernamePasswordAuthenticationToken
              && (!CasProcessingFilter.CAS_STATEFUL_IDENTIFIER.equals(authentication.getPrincipal().toString())
              && !CasProcessingFilter.CAS_STATELESS_IDENTIFIER.equals(authentication.getPrincipal().toString()))) {
              // UsernamePasswordAuthenticationToken not CAS related
              return null;
          }
  
          // If an existing CasAuthenticationToken, just check we created it
          if (authentication instanceof CasAuthenticationToken) {
              if (key.hashCode() == ((CasAuthenticationToken) authentication).getKeyHash()) {
                  return authentication;
              } else {
                  throw new BadCredentialsException(messages.getMessage("CasAuthenticationProvider.incorrectKey",
                          "The presented CasAuthenticationToken does not contain the expected key"));
              }
          }
  
          // Ensure credentials are presented
          if ((authentication.getCredentials() == null) || "".equals(authentication.getCredentials())) {
              throw new BadCredentialsException(messages.getMessage("CasAuthenticationProvider.noServiceTicket",
                      "Failed to provide a CAS service ticket to validate"));
          }
  
          boolean stateless = false;
  
          if (authentication instanceof UsernamePasswordAuthenticationToken
              && CasProcessingFilter.CAS_STATELESS_IDENTIFIER.equals(authentication.getPrincipal())) {
              stateless = true;
          }
  
          CasAuthenticationToken result = null;
  
          if (stateless) {
              // Try to obtain from cache
              result = statelessTicketCache.getByTicketId(authentication.getCredentials().toString());
          }
  
          if (result == null) {
              result = this.authenticateNow(authentication);
             result.setDetails(authentication.getDetails());
         }
 
         if (stateless) {
             // Add to cache
             statelessTicketCache.putTicketInCache(result);
         }
 
         return result;
     }
     
     /**
      * This overridden method is differs from the super method by 
      * populating the user details by passing the full response
      * 
      * @see org.acegisecurity.providers.cas.CasAuthenticationProvider#authenticateNow(Authentication authentication)
      */
     private CasAuthenticationToken authenticateNow(Authentication authentication) throws AuthenticationException {
         // Validate
         KualiTicketResponse response = (KualiTicketResponse)this.getTicketValidator().confirmTicketValid(authentication.getCredentials().toString());
 
         // Check proxy list is trusted
         this.getCasProxyDecider().confirmProxyListTrusted(response.getProxyList());
         if (logger.isDebugEnabled()) {
             logger.debug("authenticationNOW:" + response);
         }
         // Lookup user details      
         logger.debug("\n\npopulating authorities\n\n");
         UserDetails userDetails = ((KualiCasAuthoritiesPopulator)this.getCasAuthoritiesPopulator()).getUserDetails(response);        
 
         // Construct CasAuthenticationToken
         return new CasAuthenticationToken(this.getKey(), userDetails, authentication.getCredentials(),
             userDetails.getAuthorities(), userDetails, response.getProxyList(), response.getProxyGrantingTicketIou());
     }
 }