/*

  * Licensed to the Apache Software Foundation (ASF) under one

  * or more contributor license agreements.  See the NOTICE file

  * distributed with this work for additional information

  * regarding copyright ownership.  The ASF licenses this file

  * to you 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.apache.shiro.authz.aop;

 import org.apache.shiro.authz.AuthorizationException;

 import org.apache.shiro.authz.annotation.Logical;

 import org.apache.shiro.authz.annotation.RequiresPermissions;

 import org.apache.shiro.authz.annotation.RequiresRoles;

 import org.apache.shiro.subject.Subject;

 import java.lang.annotation.Annotation;

 /**

  * Checks to see if a @{@link org.apache.shiro.authz.annotation.RequiresPermissions RequiresPermissions} annotation is

  * declared, and if so, performs a permission check to see if the calling <code>Subject</code> is allowed continued

  * access.

  *

  * @since 0.9.0

  */

 public class PermissionAnnotationHandler extends AuthorizingAnnotationHandler {

     /**

      * Default no-argument constructor that ensures this handler looks for

      * {@link org.apache.shiro.authz.annotation.RequiresPermissions RequiresPermissions} annotations.

      */

     public PermissionAnnotationHandler() {

         super(RequiresPermissions.class);

     }

     /**

      * Returns the annotation {@link RequiresPermissions#value value}, from which the Permission will be constructed.

      *

      * @param a the RequiresPermissions annotation being inspected.

      * @return the annotation's <code>value</code>, from which the Permission will be constructed.

      */

     protected String[] getAnnotationValue(Annotation a) {

         RequiresPermissions rpAnnotation = (RequiresPermissions) a;

         return rpAnnotation.value();

     }

     /**

      * Ensures that the calling <code>Subject</code> has the Annotation's specified permissions, and if not, throws an

      * <code>AuthorizingException</code> indicating access is denied.

      *

      * @param a the RequiresPermission annotation being inspected to check for one or more permissions

      * @throws org.apache.shiro.authz.AuthorizationException

      *          if the calling <code>Subject</code> does not have the permission(s) necessary to

      *          continue access or execution.

      */

     public void assertAuthorized(Annotation a) throws AuthorizationException {

         if (!(a instanceof RequiresPermissions)) return;

         RequiresPermissions rpAnnotation = (RequiresPermissions) a;

         String[] perms = getAnnotationValue(a);

         Subject subject = getSubject();

         if (perms.length == 1) {

             subject.checkPermission(perms[0]);

             return;

         }

         if (Logical.AND.equals(rpAnnotation.logical())) {

             getSubject().checkPermissions(perms);

             return;

         }

         if (Logical.OR.equals(rpAnnotation.logical())) {

             // Avoid processing exceptions unnecessarily - "delay" throwing the exception by calling hasRole first

             boolean hasAtLeastOnePermission = false;

             for (String permission : perms) if (getSubject().isPermitted(permission)) hasAtLeastOnePermission = true;

             // Cause the exception if none of the role match, note that the exception message will be a bit misleading

             if (!hasAtLeastOnePermission) getSubject().checkPermission(perms[0]);

         }

     }

 }