/* 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 org.acegisecurity.Authentication;

 import org.acegisecurity.AuthorizationServiceException;

 import org.acegisecurity.ConfigAttribute;

 import org.acegisecurity.ConfigAttributeDefinition;

 import org.acegisecurity.acl.AclEntry;

 import org.acegisecurity.acl.AclManager;

 import org.acegisecurity.acl.basic.BasicAclEntry;

 import org.acegisecurity.acl.basic.SimpleAclEntry;

 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.lang.reflect.InvocationTargetException;

 import java.lang.reflect.Method;

 import java.util.Iterator;

 /**

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

  * as defined by the {@link AclManager}.</p>

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

  * domain object instance for the current <code>Authentication</code> object. This class is designed to process {@link

  * AclEntry}s that are subclasses of {@link org.acegisecurity.acl.basic.BasicAclEntry} only. Generally these are

  * obtained by using the {@link org.acegisecurity.acl.basic.BasicAclProvider}.</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

  * org.acegisecurity.acl.basic.BasicAclEntry#isPermitted(int)} for at least one of the {@link #requirePermission}s.</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>BasicAclEntryVoter</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>BasicAclEntryVoter</code>:

  *  <ul>

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

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

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

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

  *      <code>SimpleAclEntry.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>SimpleAclEntry.READ</code></li>

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

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

  *      <code>SimpleAclEntry.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>The <code>AclManager</code> is allowed to return any implementations of <code>AclEntry</code> it wishes.

  * However, this provider will only be able to validate against <code>AbstractBasicAclEntry</code>s, and thus a vote

  * to deny access will be made if no <code>AclEntry</code> is of type <code>AbstractBasicAclEntry</code>.</p>

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

  *

  * @author Ben Alex

  * @version $Id: BasicAclEntryVoter.java 1766 2006-11-26 04:47:43Z benalex $

  */

 public class BasicAclEntryVoter extends AbstractAclVoter implements InitializingBean {

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

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

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

     private AclManager aclManager;

     private String internalMethod;

     private String processConfigAttribute;

     private int[] requirePermission;

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

     public void afterPropertiesSet() throws Exception {

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

         Assert.notNull(aclManager, "An aclManager is mandatory");

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

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

         }

     }

     public AclManager getAclManager() {

         return aclManager;

     }

     /**

      * 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 int[] getRequirePermission() {

         return requirePermission;

     }

     public void setAclManager(AclManager aclManager) {

         this.aclManager = aclManager;

     }

     public void setInternalMethod(String internalMethod) {

         this.internalMethod = internalMethod;

     }

     public void setProcessConfigAttribute(String processConfigAttribute) {

         this.processConfigAttribute = processConfigAttribute;

     }

     public void setRequirePermission(int[] requirePermission) {

         this.requirePermission = requirePermission;

     }

     /**

      * Allow setting permissions with String literals instead of integers as {@link #setRequirePermission(int[])}

      * 

      * @param requirePermission Permission literals

      * @see SimpleAclEntry#parsePermissions(String[]) for valid values

      */

     public void setRequirePermissionFromString(String[] requirePermission) {

         setRequirePermission(SimpleAclEntry.parsePermissions(requirePermission));

     }

     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);

                 // 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;

                 }

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

                 if ((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);

                     }

                 }

                 // Obtain the ACLs applicable to the domain object

                 AclEntry[] acls = aclManager.getAcls(domainObject, authentication);

                 // If principal has no permissions for domain object, deny

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

                     if (logger.isDebugEnabled()) {

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

                     }

                     return AccessDecisionVoter.ACCESS_DENIED;

                 }

                 // Principal has some permissions for domain object, check them

                 for (int i = 0; i < acls.length; i++) {

                     // Locate processable AclEntrys

                     if (acls[i] instanceof BasicAclEntry) {

                         BasicAclEntry processableAcl = (BasicAclEntry) acls[i];

                         // See if principal has any of the required permissions

                         for (int y = 0; y < requirePermission.length; y++) {

                             if (processableAcl.isPermitted(requirePermission[y])) {

                                 if (logger.isDebugEnabled()) {

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

                                 }

                                 return AccessDecisionVoter.ACCESS_GRANTED;

                             }

                         }

                     }

                 }

                 // No permissions match

                 if (logger.isDebugEnabled()) {

                     logger.debug(

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

                 }

                 return AccessDecisionVoter.ACCESS_DENIED;

             }

         }

         // No configuration attribute matched, so abstain

         return AccessDecisionVoter.ACCESS_ABSTAIN;

     }

 }