/**
    * 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.zookeeper;
  
  import java.io.IOException;
  
  import org.apache.hadoop.hbase.Abortable;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.exceptions.DeserializationException;
  import org.apache.hadoop.hbase.protobuf.ProtobufUtil;
  import org.apache.hadoop.hbase.protobuf.generated.SnapshotCleanupProtos;
  import org.apache.hadoop.hbase.util.Bytes;
  import org.apache.zookeeper.KeeperException;
  
  
  /**
   * Tracks status of snapshot auto cleanup based on TTL
   */
  @InterfaceAudience.Private
  public class SnapshotCleanupTracker extends ZooKeeperNodeTracker {
  
    /**
     * Constructs a new ZK node tracker.
     *
     * <p>After construction, use {@link #start} to kick off tracking.
     *
     * @param watcher reference to the {@link ZooKeeperWatcher} which also contains configuration
     *   and constants
     * @param abortable used to abort if a fatal error occurs
     */
    public SnapshotCleanupTracker(ZooKeeperWatcher watcher, Abortable abortable) {
      super(watcher, watcher.snapshotCleanupZNode, abortable);
    }
  
    /**
     * Returns the current state of the snapshot auto cleanup based on TTL
     *
     * @return <code>true</code> if the snapshot auto cleanup is enabled,
     *   <code>false</code> otherwise.
     */
    public boolean isSnapshotCleanupEnabled() {
      byte[] snapshotCleanupZNodeData = super.getData(false);
      try {
        // if data in ZK is null, use default of on.
        return snapshotCleanupZNodeData == null ||
            parseFrom(snapshotCleanupZNodeData).getSnapshotCleanupEnabled();
      } catch (DeserializationException dex) {
        LOG.error("ZK state for Snapshot Cleanup could not be parsed " +
            Bytes.toStringBinary(snapshotCleanupZNodeData), dex);
        // return false to be safe.
        return false;
      }
    }
  
    /**
     * Set snapshot auto clean on/off
     *
     * @param snapshotCleanupEnabled true if the snapshot auto cleanup should be on,
     *   false otherwise
     * @throws KeeperException if ZooKeeper operation fails
     */
    public void setSnapshotCleanupEnabled(final boolean snapshotCleanupEnabled)
        throws KeeperException {
      byte [] snapshotCleanupZNodeData = toByteArray(snapshotCleanupEnabled);
      try {
        ZKUtil.setData(watcher, watcher.snapshotCleanupZNode,
            snapshotCleanupZNodeData);
      } catch(KeeperException.NoNodeException nne) {
        ZKUtil.createAndWatch(watcher, watcher.snapshotCleanupZNode,
            snapshotCleanupZNodeData);
      }
      super.nodeDataChanged(watcher.snapshotCleanupZNode);
    }
  
    private byte[] toByteArray(final boolean isSnapshotCleanupEnabled) {
      SnapshotCleanupProtos.SnapshotCleanupState.Builder builder =
          SnapshotCleanupProtos.SnapshotCleanupState.newBuilder();
      builder.setSnapshotCleanupEnabled(isSnapshotCleanupEnabled);
      return ProtobufUtil.prependPBMagic(builder.build().toByteArray());
    }
  
    private SnapshotCleanupProtos.SnapshotCleanupState parseFrom(final byte[] pbBytes)
        throws DeserializationException {
     ProtobufUtil.expectPBMagicPrefix(pbBytes);
     SnapshotCleanupProtos.SnapshotCleanupState.Builder builder =
         SnapshotCleanupProtos.SnapshotCleanupState.newBuilder();
     try {
       int magicLen = ProtobufUtil.lengthOfPBMagic();
       ProtobufUtil.mergeFrom(builder, pbBytes, magicLen, pbBytes.length - magicLen);
     } catch (IOException e) {
       throw new DeserializationException(e);
     }
     return builder.build();
   }
 
 }