/* 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.vote;

 import java.lang.reflect.InvocationTargetException;

 import java.lang.reflect.Method;

 import java.util.Iterator;

 import org.acegisecurity.Authentication;

 import org.acegisecurity.AuthorizationServiceException;

 import org.acegisecurity.ConfigAttribute;

 import org.acegisecurity.ConfigAttributeDefinition;

 import org.acegisecurity.acls.Acl;

 import org.acegisecurity.acls.AclService;

 import org.acegisecurity.acls.NotFoundException;

 import org.acegisecurity.acls.Permission;

 import org.acegisecurity.acls.objectidentity.ObjectIdentity;

 import org.acegisecurity.acls.objectidentity.ObjectIdentityRetrievalStrategy;

 import org.acegisecurity.acls.objectidentity.ObjectIdentityRetrievalStrategyImpl;

 import org.acegisecurity.acls.sid.Sid;

 import org.acegisecurity.acls.sid.SidRetrievalStrategy;

 import org.acegisecurity.acls.sid.SidRetrievalStrategyImpl;

 import org.apache.commons.logging.Log;

 import org.apache.commons.logging.LogFactory;

 import org.springframework.util.Assert;

 /**

  * <p>Given a domain object instance passed as a method argument, ensures the principal has appropriate permission

  * as indicated by the {@link AclService}.</p>

  *  <p>The <code>AclService</code> is used to retrieve the access control list (ACL) permissions associated with a

  * domain object instance for the current <code>Authentication</code> object.</p>

  *  <p>The voter will vote if any  {@link ConfigAttribute#getAttribute()} matches the {@link

  * #processConfigAttribute}. The provider will then locate the first method argument of type {@link

  * #processDomainObjectClass}. Assuming that method argument is non-null, the provider will then lookup the ACLs from

  * the <code>AclManager</code> and ensure the principal is  {@link Acl#isGranted(org.acegisecurity.acls.Permission[],

  * org.acegisecurity.acls.sid.Sid[], boolean)}  when presenting the {@link #requirePermission} array to that method.</p>

  *  <p>If the method argument is <code>null</code>, the voter will abstain from voting. If the method argument

  * could not be found, an {@link org.acegisecurity.AuthorizationServiceException} will be thrown.</p>

  *  <p>In practical terms users will typically setup a number of <code>AclEntryVoter</code>s. Each will have a

  * different {@link #processDomainObjectClass}, {@link #processConfigAttribute} and {@link #requirePermission}

  * combination. For example, a small application might employ the following instances of <code>AclEntryVoter</code>:

  *  <ul>

  *      <li>Process domain object class <code>BankAccount</code>, configuration attribute

  *      <code>VOTE_ACL_BANK_ACCONT_READ</code>, require permission <code>BasePermission.READ</code></li>

  *      <li>Process domain object class <code>BankAccount</code>, configuration attribute

  *      <code>VOTE_ACL_BANK_ACCOUNT_WRITE</code>, require permission list <code>BasePermission.WRITE</code> and

  *      <code>BasePermission.CREATE</code> (allowing the principal to have <b>either</b> of these two permissions</li>

  *      <li>Process domain object class <code>Customer</code>, configuration attribute

  *      <code>VOTE_ACL_CUSTOMER_READ</code>, require permission <code>BasePermission.READ</code></li>

  *      <li>Process domain object class <code>Customer</code>, configuration attribute

  *      <code>VOTE_ACL_CUSTOMER_WRITE</code>, require permission list <code>BasePermission.WRITE</code> and

  *      <code>BasePermission.CREATE</code></li>

  *  </ul>

  *  Alternatively, you could have used a common superclass or interface for the {@link #processDomainObjectClass}

  * if both <code>BankAccount</code> and <code>Customer</code> had common parents.</p>

  *  <p>If the principal does not have sufficient permissions, the voter will vote to deny access.</p>

  *  <p>All comparisons and prefixes are case sensitive.</p>

  *

  * @author Ben Alex

  * @version $Id: AclEntryVoter.java 1784 2007-02-24 21:00:24Z luke_t $

  */

 public class AclEntryVoter extends AbstractAclVoter {

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

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

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

     private AclService aclService;

     private ObjectIdentityRetrievalStrategy objectIdentityRetrievalStrategy = new ObjectIdentityRetrievalStrategyImpl();

     private SidRetrievalStrategy sidRetrievalStrategy = new SidRetrievalStrategyImpl();

     private String internalMethod;

     private String processConfigAttribute;

     private Permission[] requirePermission;

     //~ Constructors ===================================================================================================

     public AclEntryVoter(AclService aclService, String processConfigAttribute, Permission[] requirePermission) {

         Assert.notNull(processConfigAttribute, "A processConfigAttribute is mandatory");

         Assert.notNull(aclService, "An AclService is mandatory");

         if ((requirePermission == null) || (requirePermission.length == 0)) {

             throw new IllegalArgumentException("One or more requirePermission entries is mandatory");

         }

         this.aclService = aclService;

         this.processConfigAttribute = processConfigAttribute;

         this.requirePermission = requirePermission;

     }

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

     /**

      * Optionally specifies a method of the domain object that will be used to obtain a contained domain

      * object. That contained domain object will be used for the ACL evaluation. This is useful if a domain object

      * contains a parent that an ACL evaluation should be targeted for, instead of the child domain object (which

      * perhaps is being created and as such does not yet have any ACL permissions)

      *

      * @return <code>null</code> to use the domain object, or the name of a method (that requires no arguments) that

      *         should be invoked to obtain an <code>Object</code> which will be the domain object used for ACL

      *         evaluation

      */

     public String getInternalMethod() {

         return internalMethod;

     }

     public String getProcessConfigAttribute() {

         return processConfigAttribute;

     }

     public void setInternalMethod(String internalMethod) {

         this.internalMethod = internalMethod;

     }

     public void setObjectIdentityRetrievalStrategy(ObjectIdentityRetrievalStrategy objectIdentityRetrievalStrategy) {

         Assert.notNull(objectIdentityRetrievalStrategy, "ObjectIdentityRetrievalStrategy required");

         this.objectIdentityRetrievalStrategy = objectIdentityRetrievalStrategy;

     }

     public void setSidRetrievalStrategy(SidRetrievalStrategy sidRetrievalStrategy) {

         Assert.notNull(sidRetrievalStrategy, "SidRetrievalStrategy required");

         this.sidRetrievalStrategy = sidRetrievalStrategy;

     }

     public boolean supports(ConfigAttribute attribute) {

         if ((attribute.getAttribute() != null) && attribute.getAttribute().equals(getProcessConfigAttribute())) {

             return true;

         } else {

             return false;

         }

     }

     public int vote(Authentication authentication, Object object, ConfigAttributeDefinition config) {

         Iterator iter = config.getConfigAttributes();

         while (iter.hasNext()) {

             ConfigAttribute attr = (ConfigAttribute) iter.next();

             if (this.supports(attr)) {

                 // Need to make an access decision on this invocation

                 // Attempt to locate the domain object instance to process

                 Object domainObject = getDomainObjectInstance(object);

                 // Evaluate if we are required to use an inner domain object

                 if (domainObject != null && internalMethod != null && (!"".equals(internalMethod))) {

                     try {

                         Class clazz = domainObject.getClass();

                         Method method = clazz.getMethod(internalMethod, new Class[] {});

                         domainObject = method.invoke(domainObject, new Object[] {});

                     } catch (NoSuchMethodException nsme) {

                         throw new AuthorizationServiceException("Object of class '" + domainObject.getClass()

                             + "' does not provide the requested internalMethod: " + internalMethod);

                     } catch (IllegalAccessException iae) {

                         if (logger.isDebugEnabled()) {

                             logger.debug("IllegalAccessException", iae);

                             if (iae.getCause() != null) {

                                 logger.debug("Cause: " + iae.getCause().getMessage(), iae.getCause());

                             }

                         }

                         throw new AuthorizationServiceException("Problem invoking internalMethod: " + internalMethod

                             + " for object: " + domainObject);

                     } catch (InvocationTargetException ite) {

                         if (logger.isDebugEnabled()) {

                             logger.debug("InvocationTargetException", ite);

                             if (ite.getCause() != null) {

                                 logger.debug("Cause: " + ite.getCause().getMessage(), ite.getCause());

                             }

                         }

                         throw new AuthorizationServiceException("Problem invoking internalMethod: " + internalMethod

                             + " for object: " + domainObject);

                     }

                 }

                 // If domain object is null, vote to abstain

                 if (domainObject == null) {

                     if (logger.isDebugEnabled()) {

                         logger.debug("Voting to abstain - domainObject is null");

                     }

                     return AccessDecisionVoter.ACCESS_ABSTAIN;

                 }

                 // Obtain the OID applicable to the domain object

                 ObjectIdentity objectIdentity = objectIdentityRetrievalStrategy.getObjectIdentity(domainObject);

                 // Obtain the SIDs applicable to the principal

                 Sid[] sids = sidRetrievalStrategy.getSids(authentication);

                 Acl acl;

                 try {

                     // Lookup only ACLs for SIDs we're interested in

                     acl = aclService.readAclById(objectIdentity, sids);

                 } catch (NotFoundException nfe) {

                     if (logger.isDebugEnabled()) {

                         logger.debug("Voting to deny access - no ACLs apply for this principal");

                     }

                     return AccessDecisionVoter.ACCESS_DENIED;

                 }

                 try {

                     if (acl.isGranted(requirePermission, sids, false)) {

                         if (logger.isDebugEnabled()) {

                             logger.debug("Voting to grant access");

                         }

                         return AccessDecisionVoter.ACCESS_GRANTED;

                     } else {

                         if (logger.isDebugEnabled()) {

                             logger.debug(

                                 "Voting to deny access - ACLs returned, but insufficient permissions for this principal");

                         }

                         return AccessDecisionVoter.ACCESS_DENIED;

                     }

                 } catch (NotFoundException nfe) {

                     if (logger.isDebugEnabled()) {

                         logger.debug("Voting to deny access - no ACLs apply for this principal");

                     }

                     return AccessDecisionVoter.ACCESS_DENIED;

                 }

             }

         }

         // No configuration attribute matched, so abstain

         return AccessDecisionVoter.ACCESS_ABSTAIN;

     }

 }