/*
 * 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.springframework.security.acls.model;

import java.util.List;
import java.util.Map;

/**
 * Provides retrieval of {@link Acl} instances.
 *
 * @author Ben Alex
 */
public interface AclService {
	// ~ Methods
	// ========================================================================================================

	/**
	 * Locates all object identities that use the specified parent. This is useful for
	 * administration tools.
	 *
	 * @param parentIdentity to locate children of
	 *
	 * @return the children (or <tt>null</tt> if none were found)
	 */
	List<ObjectIdentity> findChildren(ObjectIdentity parentIdentity);

	/**
	 * Same as {@link #readAclsById(List)} except it returns only a single Acl.
	 * <p>
	 * This method should not be called as it does not leverage the underlying
	 * implementation's potential ability to filter <tt>Acl</tt> entries based on a
	 * {@link Sid} parameter.
	 * </p>
	 *
	 * @param object to locate an {@link Acl} for
	 *
	 * @return the {@link Acl} for the requested {@link ObjectIdentity} (never
	 * <tt>null</tt>)
	 *
	 * @throws NotFoundException if an {@link Acl} was not found for the requested
	 * {@link ObjectIdentity}
	 */
	Acl readAclById(ObjectIdentity object) throws NotFoundException;

	/**
	 * Same as {@link #readAclsById(List, List)} except it returns only a single Acl.
	 *
	 * @param object to locate an {@link Acl} for
	 * @param sids the security identities for which {@link Acl} information is required
	 * (may be <tt>null</tt> to denote all entries)
	 *
	 * @return the {@link Acl} for the requested {@link ObjectIdentity} (never
	 * <tt>null</tt>)
	 *
	 * @throws NotFoundException if an {@link Acl} was not found for the requested
	 * {@link ObjectIdentity}
	 */
	Acl readAclById(ObjectIdentity object, List<Sid> sids) throws NotFoundException;

	/**
	 * Obtains all the <tt>Acl</tt>s that apply for the passed <tt>Object</tt>s.
	 * <p>
	 * The returned map is keyed on the passed objects, with the values being the
	 * <tt>Acl</tt> instances. Any unknown objects will not have a map key.
	 * </p>
	 *
	 * @param objects the objects to find {@link Acl} information for
	 *
	 * @return a map with exactly one element for each {@link ObjectIdentity} passed as an
	 * argument (never <tt>null</tt>)
	 *
	 * @throws NotFoundException if an {@link Acl} was not found for each requested
	 * {@link ObjectIdentity}
	 */
	Map<ObjectIdentity, Acl> readAclsById(List<ObjectIdentity> objects)
			throws NotFoundException;

	/**
	 * Obtains all the <tt>Acl</tt>s that apply for the passed <tt>Object</tt>s, but only
	 * for the security identifies passed.
	 * <p>
	 * Implementations <em>MAY</em> provide a subset of the ACLs via this method although
	 * this is NOT a requirement. This is intended to allow performance optimisations
	 * within implementations. Callers should therefore use this method in preference to
	 * the alternative overloaded version which does not have performance optimisation
	 * opportunities.
	 * </p>
	 * <p>
	 * The returned map is keyed on the passed objects, with the values being the
	 * <tt>Acl</tt> instances. Any unknown objects (or objects for which the interested
	 * <tt>Sid</tt>s do not have entries) will not have a map key.
	 * </p>
	 *
	 * @param objects the objects to find {@link Acl} information for
	 * @param sids the security identities for which {@link Acl} information is required
	 * (may be <tt>null</tt> to denote all entries)
	 *
	 * @return a map with exactly one element for each {@link ObjectIdentity} passed as an
	 * argument (never <tt>null</tt>)
	 *
	 * @throws NotFoundException if an {@link Acl} was not found for each requested
	 * {@link ObjectIdentity}
	 */
	Map<ObjectIdentity, Acl> readAclsById(List<ObjectIdentity> objects, List<Sid> sids)
			throws NotFoundException;
}
