/**
 * Copyright (c) 2002-2012 "Neo Technology,"
 * Network Engine for Objects in Lund AB [http://neotechnology.com]
 *
 * This file is part of Neo4j.
 *
 * Neo4j is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */

package org.neo4j.cluster.protocol.cluster;

import java.net.URI;

/**
 * Listener interface for cluster configuration changes. Register instances
 * of this interface with {@link Cluster}
 */
public interface ClusterListener
{
    /**
     * When I enter the cluster as a member, this callback notifies me
     * that this has been agreed upon by the entire cluster.
     *
     * @param clusterConfiguration
     */
    void enteredCluster( ClusterConfiguration clusterConfiguration );

    /**
     * When I leave the cluster, this callback notifies me
     * that this has been agreed upon by the entire cluster.
     */
    void leftCluster();

    /**
     * When another instance joins as a member, this callback is invoked
     *
     * @param member
     */
    void joinedCluster( URI member );

    /**
     * When another instance leaves the cluster, this callback is invoked.
     * Implicitly, any roles that this member had, are revoked.
     *
     * @param member
     */
    void leftCluster( URI member );

    /**
     * When a member (including potentially myself) has been elected to a particular role, this callback is invoked.
     * Combine this callback with the leftCluster to keep track of current set of role->member mappings.
     *
     * @param role
     * @param electedMember
     */
    void elected( String role, URI electedMember );

    public abstract class Adapter
            implements ClusterListener
    {
        @Override
        public void enteredCluster( ClusterConfiguration clusterConfiguration )
        {
        }

        @Override
        public void joinedCluster( URI member )
        {
        }

        @Override
        public void leftCluster( URI member )
        {
        }

        @Override
        public void leftCluster()
        {
        }

        @Override
        public void elected( String role, URI electedMember )
        {
        }
    }
}