/* 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.acl;

 import org.acegisecurity.Authentication;

 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.util.Iterator;

 import java.util.List;

 /**

  * Iterates through a list of {@link AclProvider}s to locate the ACLs that apply to a given domain object instance.<P>If

  * no compatible provider is found, it is assumed that no ACLs apply for the specified domain object instance and

  * <code>null</code> is returned.</p>

  *

  * @author Ben Alex

  * @version $Id: AclProviderManager.java 1496 2006-05-23 13:38:33Z benalex $

  */

 public class AclProviderManager implements AclManager, InitializingBean {

     //~ Static fields/initializers =====================================================================================

     private static final Log logger = LogFactory.getLog(AclProviderManager.class);

     //~ Instance fields ================================================================================================

     private List providers;

     //~ Methods ========================================================================================================

     public void afterPropertiesSet() throws Exception {

         checkIfValidList(this.providers);

     }

     private void checkIfValidList(List listToCheck) {

         Assert.notEmpty(listToCheck, "A list of AclManagers is required");

     }

     public AclEntry[] getAcls(Object domainInstance) {

         Assert.notNull(domainInstance, "domainInstance is null - violating interface contract");

         Iterator iter = providers.iterator();

         while (iter.hasNext()) {

             AclProvider provider = (AclProvider) iter.next();

             if (provider.supports(domainInstance)) {

                 if (logger.isDebugEnabled()) {

                     logger.debug("ACL lookup using " + provider.getClass().getName());

                 }

                 return provider.getAcls(domainInstance);

             }

         }

         if (logger.isDebugEnabled()) {

             logger.debug("No AclProvider found for " + domainInstance.toString());

         }

         return null;

     }

     public AclEntry[] getAcls(Object domainInstance, Authentication authentication) {

         Assert.notNull(domainInstance, "domainInstance is null - violating interface contract");

         Assert.notNull(authentication, "authentication is null - violating interface contract");

         Iterator iter = providers.iterator();

         while (iter.hasNext()) {

             AclProvider provider = (AclProvider) iter.next();

             if (provider.supports(domainInstance)) {

                 if (logger.isDebugEnabled()) {

                     logger.debug("ACL lookup using " + provider.getClass().getName());

                 }

                 return provider.getAcls(domainInstance, authentication);

             } else {

                 if (logger.isDebugEnabled()) {

                     logger.debug("Provider " + provider.toString() + " does not support " + domainInstance);

                 }

             }

         }

         if (logger.isDebugEnabled()) {

             logger.debug("No AclProvider found for " + domainInstance.toString());

         }

         return null;

     }

     public List getProviders() {

         return this.providers;

     }

     /**

      * Sets the {@link AclProvider} objects to be used for ACL determinations.

      *

      * @param newList that should be used for ACL determinations

      *

      * @throws IllegalArgumentException if an invalid provider was included in the list

      */

     public void setProviders(List newList) {

         checkIfValidList(newList);

         Iterator iter = newList.iterator();

         while (iter.hasNext()) {

             Object currentObject = null;

             try {

                 currentObject = iter.next();

                 AclProvider attemptToCast = (AclProvider) currentObject;

             } catch (ClassCastException cce) {

                 throw new IllegalArgumentException("AclProvider " + currentObject.getClass().getName()

                     + " must implement AclProvider");

             }

         }

         this.providers = newList;

     }

 }