/*
 * @(#)file      OwnerImpl.java
 * @(#)author    Sun Microsystems, Inc.
 * @(#)version   4.9
 * @(#)date      04/09/15
 *
 * Copyright 2004 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
 */


package com.sun.jmx.snmp.IPAcl;



import java.util.Vector;
import java.io.Serializable;

import java.security.Principal;
import java.security.acl.Owner; 
import java.security.acl.LastOwnerException; 
import java.security.acl.NotOwnerException; 


/**
 * Owner of Access Control Lists (ACLs).
 * The initial owner Principal should be specified as an
 * argument to the constructor of the class AclImpl.
 *
 * @see java.security.acl.Owner
 * @version     4.9     12/19/03
 * @author      Sun Microsystems, Inc
 */

class OwnerImpl implements Owner, Serializable {
  private Vector ownerList = null;
  
  /**
   * Constructs an empty list of owner.
   */
  public OwnerImpl (){
	ownerList = new Vector();
  }
  
  /**
   * Constructs a list of owner with the specified principal as first element.
   *
   * @param owner the principal added to the owner list.
   */
  public OwnerImpl (PrincipalImpl owner){
	ownerList = new Vector();
	ownerList.addElement(owner);
  }
  
  /**
   * Adds an owner. Only owners can modify ACL contents. The caller principal
   * must be an owner of the ACL in order to invoke this method. That is, only
   * an owner can add another owner. The initial owner is configured at
   * ACL construction time.
   *
   * @param caller the principal invoking this method. 
   *        It must be an owner of the ACL.
   * @param owner the owner that should be added to the list of owners.
   * @return true if successful, false if owner is already an owner. 
   * @exception NotOwnerException if the caller principal is not an owner 
   *    of the ACL. 
   */
  public boolean addOwner(Principal caller, Principal owner) 
	throws NotOwnerException {
	if (!ownerList.contains(caller)) 
	  throw new NotOwnerException();

	if (ownerList.contains(owner)) {
	  return false;
	} else {
	  ownerList.addElement(owner);
	  return true;
	}
  }
  
  /**
   * Deletes an owner. If this is the last owner in the ACL, an exception is raised.
   *<P>
   * The caller principal must be an owner of the ACL in order to invoke this method. 
   *
   * @param caller the principal invoking this method. It must be an owner 
   *   of the ACL. 
   * @param owner the owner to be removed from the list of owners. 
   * @return true if successful, false if owner is already an owner. 
   * @exception NotOwnerException if the caller principal is not an owner 
   *   of the ACL. 
   * @exception LastOwnerException if there is only one owner left, so that 
   *   deleteOwner would leave the ACL owner-less.
   */
  public boolean deleteOwner(Principal caller, Principal owner)
		throws NotOwnerException,LastOwnerException {

	if (!ownerList.contains(caller))
	  throw new NotOwnerException();
	
	if (!ownerList.contains(owner)){
	  return false;
	} else {
	  if (ownerList.size() == 1)
		throw new LastOwnerException();
	  
	  ownerList.removeElement(owner);
	  return true;
	}
  }
  
  /**
   * Returns true if the given principal is an owner of the ACL.
   *
   * @param owner the principal to be checked to determine whether or 
   *        not it is an owner. 
   * @return true if the given principal is an owner of the ACL.
   */
  public boolean isOwner(Principal owner){
	return ownerList.contains(owner);
  }
}