/* 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.taglibs.authz;

 import org.acegisecurity.Authentication;

 import org.acegisecurity.acl.AclEntry;

 import org.acegisecurity.acl.AclManager;

 import org.acegisecurity.acl.basic.BasicAclEntry;

 import org.acegisecurity.context.SecurityContextHolder;

 import org.apache.commons.logging.Log;

 import org.apache.commons.logging.LogFactory;

 import org.springframework.beans.factory.BeanFactoryUtils;

 import org.springframework.context.ApplicationContext;

 import org.springframework.web.context.support.WebApplicationContextUtils;

 import org.springframework.web.util.ExpressionEvaluationUtils;

 import java.util.HashSet;

 import java.util.Set;

 import java.util.StringTokenizer;

 import javax.servlet.ServletContext;

 import javax.servlet.jsp.JspException;

 import javax.servlet.jsp.PageContext;

 import javax.servlet.jsp.tagext.Tag;

 import javax.servlet.jsp.tagext.TagSupport;

 /**

  * An implementation of {@link javax.servlet.jsp.tagext.Tag} that allows its body through if some authorizations

  * are granted to the request's principal.<P>Only works with permissions that are subclasses of {@link

  * org.acegisecurity.acl.basic.BasicAclEntry}.</p>

  *  <p>One or more comma separate integer permissions are specified via the <code>hasPermission</code> attribute.

  * The tag will include its body if <b>any</b> of the integer permissions have been granted to the current

  * <code>Authentication</code> (obtained from the <code>SecurityContextHolder</code>).</p>

  *  <p>For this class to operate it must be able to access the application context via the

  * <code>WebApplicationContextUtils</code> and locate an {@link AclManager}. Application contexts have no need to have

  * more than one <code>AclManager</code> (as a provider-based implementation can be used so that it locates a provider

  * that is authoritative for the given domain object instance), so the first <code>AclManager</code> located will be

  * used.</p>

  *

  * @author Ben Alex

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

  */

 public class AclTag extends TagSupport {

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

     protected static final Log logger = LogFactory.getLog(AclTag.class);

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

     private Object domainObject;

     private String hasPermission = "";

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

     public int doStartTag() throws JspException {

         if ((null == hasPermission) || "".equals(hasPermission)) {

             return Tag.SKIP_BODY;

         }

         final String evaledPermissionsString = ExpressionEvaluationUtils.evaluateString("hasPermission", hasPermission,

                 pageContext);

         Integer[] requiredIntegers = null;

         try {

             requiredIntegers = parseIntegersString(evaledPermissionsString);

         } catch (NumberFormatException nfe) {

             throw new JspException(nfe);

         }

         Object resolvedDomainObject = null;

         if (domainObject instanceof String) {

             resolvedDomainObject = ExpressionEvaluationUtils.evaluate("domainObject", (String) domainObject,

                     Object.class, pageContext);

         } else {

             resolvedDomainObject = domainObject;

         }

         if (resolvedDomainObject == null) {

             if (logger.isDebugEnabled()) {

                 logger.debug("domainObject resolved to null, so including tag body");

             }

             // Of course they have access to a null object!

             return Tag.EVAL_BODY_INCLUDE;

         }

         if (SecurityContextHolder.getContext().getAuthentication() == null) {

             if (logger.isDebugEnabled()) {

                 logger.debug(

                     "SecurityContextHolder did not return a non-null Authentication object, so skipping tag body");

             }

             return Tag.SKIP_BODY;

         }

         Authentication auth = SecurityContextHolder.getContext().getAuthentication();

         ApplicationContext context = getContext(pageContext);

         String[] beans = BeanFactoryUtils.beanNamesForTypeIncludingAncestors(context, AclManager.class, false, false);

         if (beans.length == 0) {

             throw new JspException("No AclManager would found the application context: " + context.toString());

         }

         AclManager aclManager = (AclManager) context.getBean(beans[0]);

         // Obtain aclEntrys applying to the current Authentication object

         AclEntry[] acls = aclManager.getAcls(resolvedDomainObject, auth);

         if (logger.isDebugEnabled()) {

             logger.debug("Authentication: '" + auth + "' has: " + ((acls == null) ? 0 : acls.length)

                 + " AclEntrys for domain object: '" + resolvedDomainObject + "' from AclManager: '"

                 + aclManager.toString() + "'");

         }

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

             return Tag.SKIP_BODY;

         }

         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 < requiredIntegers.length; y++) {

                     if (processableAcl.isPermitted(requiredIntegers[y].intValue())) {

                         if (logger.isDebugEnabled()) {

                             logger.debug("Including tag body as found permission: " + requiredIntegers[y]

                                 + " due to AclEntry: '" + processableAcl + "'");

                         }

                         return Tag.EVAL_BODY_INCLUDE;

                     }

                 }

             }

         }

         if (logger.isDebugEnabled()) {

             logger.debug("No permission, so skipping tag body");

         }

         return Tag.SKIP_BODY;

     }

     /**

      * Allows test cases to override where application context obtained from.

      *

      * @param pageContext so the <code>ServletContext</code> can be accessed as required by Spring's

      *        <code>WebApplicationContextUtils</code>

      *

      * @return the Spring application context (never <code>null</code>)

      */

     protected ApplicationContext getContext(PageContext pageContext) {

         ServletContext servletContext = pageContext.getServletContext();

         return WebApplicationContextUtils.getRequiredWebApplicationContext(servletContext);

     }

     public Object getDomainObject() {

         return domainObject;

     }

     public String getHasPermission() {

         return hasPermission;

     }

     private Integer[] parseIntegersString(String integersString)

         throws NumberFormatException {

         final Set integers = new HashSet();

         final StringTokenizer tokenizer;

         tokenizer = new StringTokenizer(integersString, ",", false);

         while (tokenizer.hasMoreTokens()) {

             String integer = tokenizer.nextToken();

             integers.add(new Integer(integer));

         }

         return (Integer[]) integers.toArray(new Integer[] {});

     }

     public void setDomainObject(Object domainObject) {

         this.domainObject = domainObject;

     }

     public void setHasPermission(String hasPermission) {

         this.hasPermission = hasPermission;

     }

 }