/*
 * Copyright 2005-2010 the original author or authors.
 * 
 * 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.wamblee.security.authentication;

import java.util.Set;

/**
 * Represents a set of groups. A typical implemnetation would be, a readonly
 * implementation defined in a configuration file or a list of groups defined in
 * a database.
 * 
 * @author Erik Brakkee
 */
public interface GroupSet {
    /**
     * Must be called when the group has been modified to notify the group set.
     * 
     * @param aGroup
     *            Group that was modified.
     */
    void groupModified(Group aGroup);

    /**
     * Finds the group by name.
     * 
     * @param aName
     *            Group name.
     * 
     * @return Group or null if not found.
     */
    Group find(String aName);

    /**
     * Determines if the group exists.
     * 
     * @param aGroup
     *            Group.
     * 
     * @return True iff the group exists.
     */
    boolean contains(Group aGroup);

    /**
     * Adds a group. If the group already exists, the existing group set is left
     * unchanged.
     * 
     * @param aGroup
     *            Group.
     * 
     */
    boolean add(Group aGroup);

    /**
     * Removes a group. If the group does not exist, this method is a no-op.
     * 
     * @param aGroup
     *            Group to remove.
     * 
     * @return True if the group was removed, false otherwise.
     */
    boolean remove(Group aGroup);

    /**
     * Returns the current groups.
     * 
     * @return Groups.
     */
    Set<Group> list();

    /**
     * 
     * @return The number of groups.
     */
    int size();
}