/**
    * This file Copyright (c) 2011 Magnolia International
    * Ltd.  (http://www.magnolia-cms.com). All rights reserved.
    *
    *
    * This file is dual-licensed under both the Magnolia
    * Network Agreement and the GNU General Public License.
    * You may elect to use one or the other of these licenses.
    *
   * This file is distributed in the hope that it will be
   * useful, but AS-IS and WITHOUT ANY WARRANTY; without even the
   * implied warranty of MERCHANTABILITY or FITNESS FOR A
   * PARTICULAR PURPOSE, TITLE, or NONINFRINGEMENT.
   * Redistribution, except as permitted by whichever of the GPL
   * or MNA you select, is prohibited.
   *
   * 1. For the GPL license (GPL), you can redistribute and/or
   * modify this file under the terms of the GNU General
   * Public License, Version 3, as published by the Free Software
   * Foundation.  You should have received a copy of the GNU
   * General Public License, Version 3 along with this program;
   * if not, write to the Free Software Foundation, Inc., 51
   * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
   *
   * 2. For the Magnolia Network Agreement (MNA), this file
   * and the accompanying materials are made available under the
   * terms of the MNA which accompanies this distribution, and
   * is available at http://www.magnolia-cms.com/mna.html
   *
   * Any modifications to this file must keep this entire header
   * intact.
   *
   */
  package info.magnolia.cms.security;
  
  import java.security.Principal;
  import java.util.Iterator;
  import javax.security.auth.Subject;
  
  import info.magnolia.cms.security.auth.ACL;
  import info.magnolia.cms.security.auth.PrincipalCollection;
  
  /**
   * Utility methods for handling JAAS principals.
   *
   * @version $Id$
   */
  public class PrincipalUtil {
  
      public static Subject createSubject(User user) {
          Subject subject = new Subject();
          subject.getPrincipals().add(user);
          return subject;
      }
  
      public static <T extends Principal> T findPrincipal(Subject subject, Class<T> clazz) {
          return findPrincipal(subject.getPrincipals(), clazz, null);
      }
  
      public static ACL findAccessControlList(Iterable<Principal> principals, String name) {
          return findPrincipal(principals, ACL.class, name);
      }
  
      public static ACL findAccessControlList(Subject subject, String name) {
          return findPrincipal(subject.getPrincipals(), ACL.class, name);
      }
  
      public static <T extends Principal> T removePrincipal(Iterable<Principal> principals, Class<T> clazz) {
          return removePrincipal(principals, clazz, null);
      }
  
      private static <T extends Principal> T findPrincipal(Iterable<Principal> principals, Class<T> clazz, String name) {
          for (Principal principal : principals) {
              if (matches(principal, clazz, name)) {
                  return (T) principal;
              }
              if (principal instanceof PrincipalCollection) {
                  T t = findPrincipal((PrincipalCollection) principal, clazz, name);
                  if (t != null) {
                      return t;
                  }
              }
          }
          return null;
      }
  
      private static <T extends Principal> T removePrincipal(Iterable<Principal> principals, Class<T> clazz, String name) {
          for (Iterator<Principal> iterator = principals.iterator(); iterator.hasNext(); ) {
              Principal principal = iterator.next();
              if (matches(principal, clazz, name)) {
                  iterator.remove();
                  return (T) principal;
              }
              if (principal instanceof PrincipalCollection) {
                  T t = removePrincipal((PrincipalCollection) principal, clazz, name);
                  if (t != null) {
                      return t;
                  }
              }
         }
         return null;
     }
 
     private static boolean matches(Principal principal, Class<? extends Principal> clazz, String name) {
         return (clazz == null || clazz.isAssignableFrom(principal.getClass())) &&
                 (name == null || name.equals(principal.getName()));
     }
 }