/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.apache.hadoop.hbase.chaos.actions;

import java.util.List;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.ServerName;
import org.apache.hadoop.hbase.util.FSUtils;
import org.apache.hadoop.hbase.zookeeper.RecoverableZooKeeper;
import org.apache.hadoop.hbase.zookeeper.ZKUtil;
import org.apache.hadoop.hbase.zookeeper.ZKWatcher;
import org.apache.hadoop.hbase.zookeeper.ZNodePaths;
import org.apache.hadoop.hdfs.DFSUtil;
import org.apache.hadoop.hdfs.HAUtil;
import org.apache.hadoop.hdfs.server.namenode.ha.proto.HAZKInfoProtos.ActiveNodeInfo;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Action that tries to restart the active namenode.
 */
public class RestartActiveNameNodeAction extends RestartActionBaseAction {
  private static final Logger LOG =
      LoggerFactory.getLogger(RestartActiveNameNodeAction.class);

  // Value taken from org.apache.hadoop.ha.ActiveStandbyElector.java, variable :- LOCK_FILENAME
  private static final String ACTIVE_NN_LOCK_NAME = "ActiveStandbyElectorLock";

  // Value taken from org.apache.hadoop.ha.ZKFailoverController.java
  // variable :- ZK_PARENT_ZNODE_DEFAULT and ZK_PARENT_ZNODE_KEY
  private static final String ZK_PARENT_ZNODE_DEFAULT = "/hadoop-ha";
  private static final String ZK_PARENT_ZNODE_KEY = "ha.zookeeper.parent-znode";

  public RestartActiveNameNodeAction(long sleepTime) {
    super(sleepTime);
  }

  @Override
  public void perform() throws Exception {
    LOG.info("Performing action: Restart active namenode");
    Configuration conf = FSUtils.getRootDir(getConf()).getFileSystem(getConf()).getConf();
    String nameServiceID = DFSUtil.getNamenodeNameServiceId(conf);
    if (!HAUtil.isHAEnabled(conf, nameServiceID)) {
      throw new Exception("HA for namenode is not enabled");
    }
    ZKWatcher zkw = null;
    RecoverableZooKeeper rzk = null;
    String activeNamenode = null;
    String hadoopHAZkNode = conf.get(ZK_PARENT_ZNODE_KEY, ZK_PARENT_ZNODE_DEFAULT);
    try {
      zkw = new ZKWatcher(conf, "get-active-namenode", null);
      rzk = zkw.getRecoverableZooKeeper();
      String hadoopHAZkNodePath = ZNodePaths.joinZNode(hadoopHAZkNode, nameServiceID);
      List<String> subChildern = ZKUtil.listChildrenNoWatch(zkw, hadoopHAZkNodePath);
      for (String eachEntry : subChildern) {
        if (eachEntry.contains(ACTIVE_NN_LOCK_NAME)) {
          byte[] data =
              rzk.getData(ZNodePaths.joinZNode(hadoopHAZkNodePath, ACTIVE_NN_LOCK_NAME), false,
                null);
          ActiveNodeInfo proto = ActiveNodeInfo.parseFrom(data);
          activeNamenode = proto.getHostname();
        }
      }
    } finally {
      if (zkw != null) {
        zkw.close();
      }
    }
    if (activeNamenode == null) {
      throw new Exception("No active Name node found in zookeeper under " + hadoopHAZkNode);
    }
    LOG.info("Found active namenode host:" + activeNamenode);
    ServerName activeNNHost = ServerName.valueOf(activeNamenode, -1, -1);
    LOG.info("Restarting Active NameNode :" + activeNamenode);
    restartNameNode(activeNNHost, sleepTime);
  }
}
