/*
    *
    * 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.replication;
  
  import java.io.IOException;
  import java.util.ArrayList;
  import java.util.List;
  import java.util.Map;
  import java.util.Set;
  import java.util.TreeMap;
  import java.util.concurrent.ConcurrentHashMap;
  import java.util.concurrent.ConcurrentMap;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.hbase.HBaseConfiguration;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.conf.Configuration;
  import org.apache.hadoop.hbase.Abortable;
  import org.apache.hadoop.hbase.CompoundConfiguration;
  import org.apache.hadoop.hbase.TableName;
  import org.apache.hadoop.hbase.exceptions.DeserializationException;
  import org.apache.hadoop.hbase.protobuf.ProtobufUtil;
  import org.apache.hadoop.hbase.protobuf.generated.HBaseProtos.BytesBytesPair;
  import org.apache.hadoop.hbase.protobuf.generated.HBaseProtos.NameStringPair;
  import org.apache.hadoop.hbase.protobuf.generated.ZooKeeperProtos;
  import org.apache.hadoop.hbase.replication.ReplicationPeer.PeerState;
  import org.apache.hadoop.hbase.util.Bytes;
  import org.apache.hadoop.hbase.util.Pair;
  import org.apache.hadoop.hbase.zookeeper.ZKUtil;
  import org.apache.hadoop.hbase.zookeeper.ZooKeeperWatcher;
  import org.apache.hadoop.hbase.zookeeper.ZKUtil.ZKUtilOp;
  import org.apache.zookeeper.KeeperException;
  
  import com.google.protobuf.ByteString;
  
  /**
   * This class provides an implementation of the ReplicationPeers interface using Zookeeper. The
   * peers znode contains a list of all peer replication clusters and the current replication state of
   * those clusters. It has one child peer znode for each peer cluster. The peer znode is named with
   * the cluster id provided by the user in the HBase shell. The value of the peer znode contains the
   * peers cluster key provided by the user in the HBase Shell. The cluster key contains a list of
   * zookeeper quorum peers, the client port for the zookeeper quorum, and the base znode for HBase.
   * For example:
   *
   *  /hbase/replication/peers/1 [Value: zk1.host.com,zk2.host.com,zk3.host.com:2181:/hbase]
   *  /hbase/replication/peers/2 [Value: zk5.host.com,zk6.host.com,zk7.host.com:2181:/hbase]
   *
   * Each of these peer znodes has a child znode that indicates whether or not replication is enabled
   * on that peer cluster. These peer-state znodes do not have child znodes and simply contain a
   * boolean value (i.e. ENABLED or DISABLED). This value is read/maintained by the
   * ReplicationPeer.PeerStateTracker class. For example:
   *
   * /hbase/replication/peers/1/peer-state [Value: ENABLED]
   *
   * Each of these peer znodes has a child znode that indicates which data will be replicated
   * to the peer cluster. These peer-tableCFs znodes do not have child znodes and only have a
   * table/cf list config. This value is read/maintained by the ReplicationPeer.TableCFsTracker
   * class. For example:
   *
   * /hbase/replication/peers/1/tableCFs [Value: "table1; table2:cf1,cf3; table3:cfx,cfy"]
   */
  @InterfaceAudience.Private
  public class ReplicationPeersZKImpl extends ReplicationStateZKBase implements ReplicationPeers {
  
    // Map of peer clusters keyed by their id
    private Map<String, ReplicationPeerZKImpl> peerClusters;
    private final String tableCFsNodeName;
  
    private static final Log LOG = LogFactory.getLog(ReplicationPeersZKImpl.class);
  
    public ReplicationPeersZKImpl(final ZooKeeperWatcher zk, final Configuration conf,
        Abortable abortable) {
      super(zk, conf, abortable);
      this.tableCFsNodeName = conf.get("zookeeper.znode.replication.peers.tableCFs", "tableCFs");
      this.peerClusters = new ConcurrentHashMap<String, ReplicationPeerZKImpl>();
    }
  
    @Override
    public void init() throws ReplicationException {
      try {
        if (ZKUtil.checkExists(this.zookeeper, this.peersZNode) < 0) {
          ZKUtil.createWithParents(this.zookeeper, this.peersZNode);
       }
     } catch (KeeperException e) {
       throw new ReplicationException("Could not initialize replication peers", e);
     }
     addExistingPeers();
   }
 
   @Override
   public void addPeer(String id, ReplicationPeerConfig peerConfig, String tableCFs)
       throws ReplicationException {
     try {
       if (peerExists(id)) {
         throw new IllegalArgumentException("Cannot add a peer with id=" + id
             + " because that id already exists.");
       }
 
       if(id.contains("-") || id.equals(ReplicationQueuesZKImpl.RS_LOCK_ZNODE)) {
         throw new IllegalArgumentException("Found invalid peer name:" + id);
       }
 
       ZKUtil.createWithParents(this.zookeeper, this.peersZNode);
       List<ZKUtilOp> listOfOps = new ArrayList<ZKUtil.ZKUtilOp>();
       ZKUtilOp op1 = ZKUtilOp.createAndFailSilent(ZKUtil.joinZNode(this.peersZNode, id),
         toByteArray(peerConfig));
       // There is a race (if hbase.zookeeper.useMulti is false)
       // b/w PeerWatcher and ReplicationZookeeper#add method to create the
       // peer-state znode. This happens while adding a peer
       // The peer state data is set as "ENABLED" by default.
       ZKUtilOp op2 = ZKUtilOp.createAndFailSilent(getPeerStateNode(id), ENABLED_ZNODE_BYTES);
       String tableCFsStr = (tableCFs == null) ? "" : tableCFs;
       ZKUtilOp op3 = ZKUtilOp.createAndFailSilent(getTableCFsNode(id), Bytes.toBytes(tableCFsStr));
       listOfOps.add(op1);
       listOfOps.add(op2);
       listOfOps.add(op3);
       ZKUtil.multiOrSequential(this.zookeeper, listOfOps, false);
       // A peer is enabled by default
     } catch (KeeperException e) {
       throw new ReplicationException("Could not add peer with id=" + id
           + ", peerConfif=>" + peerConfig, e);
     }
   }
 
   @Override
   public void removePeer(String id) throws ReplicationException {
     try {
       if (!peerExists(id)) {
         throw new IllegalArgumentException("Cannot remove peer with id=" + id
             + " because that id does not exist.");
       }
       ZKUtil.deleteNodeRecursively(this.zookeeper, ZKUtil.joinZNode(this.peersZNode, id));
     } catch (KeeperException e) {
       throw new ReplicationException("Could not remove peer with id=" + id, e);
     }
   }
 
   @Override
   public void enablePeer(String id) throws ReplicationException {
     changePeerState(id, ZooKeeperProtos.ReplicationState.State.ENABLED);
     LOG.info("peer " + id + " is enabled");
   }
 
   @Override
   public void disablePeer(String id) throws ReplicationException {
     changePeerState(id, ZooKeeperProtos.ReplicationState.State.DISABLED);
     LOG.info("peer " + id + " is disabled");
   }
 
   @Override
   public String getPeerTableCFsConfig(String id) throws ReplicationException {
     try {
       if (!peerExists(id)) {
         throw new IllegalArgumentException("peer " + id + " doesn't exist");
       }
       try {
         return Bytes.toString(ZKUtil.getData(this.zookeeper, getTableCFsNode(id)));
       } catch (Exception e) {
         throw new ReplicationException(e);
       }
     } catch (KeeperException e) {
       throw new ReplicationException("Unable to get tableCFs of the peer with id=" + id, e);
     }
   }
 
   @Override
   public void setPeerTableCFsConfig(String id, String tableCFsStr) throws ReplicationException {
     try {
       if (!peerExists(id)) {
         throw new IllegalArgumentException("Cannot set peer tableCFs because id=" + id
             + " does not exist.");
       }
       String tableCFsZKNode = getTableCFsNode(id);
       byte[] tableCFs = Bytes.toBytes(tableCFsStr);
       if (ZKUtil.checkExists(this.zookeeper, tableCFsZKNode) != -1) {
         ZKUtil.setData(this.zookeeper, tableCFsZKNode, tableCFs);
       } else {
         ZKUtil.createAndWatch(this.zookeeper, tableCFsZKNode, tableCFs);
       }
       LOG.info("Peer tableCFs with id= " + id + " is now " + tableCFsStr);
     } catch (KeeperException e) {
       throw new ReplicationException("Unable to change tableCFs of the peer with id=" + id, e);
     }
   }
 
   @Override
   public Map<TableName, List<String>> getTableCFs(String id) throws IllegalArgumentException {
     ReplicationPeer replicationPeer = this.peerClusters.get(id);
     if (replicationPeer == null) {
       throw new IllegalArgumentException("Peer with id= " + id + " is not connected");
     }
     return replicationPeer.getTableCFs();
   }
 
   @Override
   public boolean getStatusOfPeer(String id) {
     ReplicationPeer replicationPeer = this.peerClusters.get(id);
     if (replicationPeer == null) {
       throw new IllegalArgumentException("Peer with id= " + id + " is not connected");
     }
     return replicationPeer.getPeerState() == PeerState.ENABLED;
   }
 
   @Override
   public boolean getStatusOfPeerFromBackingStore(String id) throws ReplicationException {
     try {
       if (!peerExists(id)) {
         throw new IllegalArgumentException("peer " + id + " doesn't exist");
       }
       String peerStateZNode = getPeerStateNode(id);
       try {
         return ReplicationPeerZKImpl.isStateEnabled(ZKUtil.getData(this.zookeeper, peerStateZNode));
       } catch (KeeperException e) {
         throw new ReplicationException(e);
       } catch (DeserializationException e) {
         throw new ReplicationException(e);
       }
     } catch (KeeperException e) {
       throw new ReplicationException("Unable to get status of the peer with id=" + id +
           " from backing store", e);
     } catch (InterruptedException e) {
       throw new ReplicationException(e);
     }
   }
 
   @Override
   public Map<String, ReplicationPeerConfig> getAllPeerConfigs() {
     Map<String, ReplicationPeerConfig> peers = new TreeMap<String, ReplicationPeerConfig>();
     List<String> ids = null;
     try {
       ids = ZKUtil.listChildrenNoWatch(this.zookeeper, this.peersZNode);
       for (String id : ids) {
         ReplicationPeerConfig peerConfig = getReplicationPeerConfig(id);
         if (peerConfig == null) {
           LOG.warn("Failed to get replication peer configuration of clusterid=" + id
             + " znode content, continuing.");
           continue;
         }
         peers.put(id, peerConfig);
       }
     } catch (KeeperException e) {
       this.abortable.abort("Cannot get the list of peers ", e);
     } catch (ReplicationException e) {
       this.abortable.abort("Cannot get the list of peers ", e);
     }
     return peers;
   }
 
   @Override
   public ReplicationPeer getPeer(String peerId) {
     return peerClusters.get(peerId);
   }
 
   @Override
   public Set<String> getPeerIds() {
     return peerClusters.keySet(); // this is not thread-safe
   }
 
   /**
    * Returns a ReplicationPeerConfig from the znode or null for the given peerId.
    */
   @Override
   public ReplicationPeerConfig getReplicationPeerConfig(String peerId)
       throws ReplicationException {
     String znode = ZKUtil.joinZNode(this.peersZNode, peerId);
     byte[] data = null;
     try {
       data = ZKUtil.getData(this.zookeeper, znode);
     } catch (InterruptedException e) {
       LOG.warn("Could not get configuration for peer because the thread " +
           "was interrupted. peerId=" + peerId);
       Thread.currentThread().interrupt();
       return null;
     } catch (KeeperException e) {
       throw new ReplicationException("Error getting configuration for peer with id="
           + peerId, e);
     }
     if (data == null) {
       LOG.error("Could not get configuration for peer because it doesn't exist. peerId=" + peerId);
       return null;
     }
 
     try {
       return parsePeerFrom(data);
     } catch (DeserializationException e) {
       LOG.warn("Failed to parse cluster key from peerId=" + peerId
           + ", specifically the content from the following znode: " + znode);
       return null;
     }
   }
 
   @Override
   public Pair<ReplicationPeerConfig, Configuration> getPeerConf(String peerId)
       throws ReplicationException {
     ReplicationPeerConfig peerConfig = getReplicationPeerConfig(peerId);
 
     if (peerConfig == null) {
       return null;
     }
 
     Configuration otherConf;
     try {
       otherConf = HBaseConfiguration.createClusterConf(this.conf, peerConfig.getClusterKey());
     } catch (IOException e) {
       LOG.error("Can't get peer configuration for peerId=" + peerId + " because:", e);
       return null;
     }
 
     if (!peerConfig.getConfiguration().isEmpty()) {
       CompoundConfiguration compound = new CompoundConfiguration();
       compound.add(otherConf);
       compound.addStringMap(peerConfig.getConfiguration());
       return new Pair<ReplicationPeerConfig, Configuration>(peerConfig, compound);
     }
 
     return new Pair<ReplicationPeerConfig, Configuration>(peerConfig, otherConf);
   }
 
   /**
    * List all registered peer clusters and set a watch on their znodes.
    */
   @Override
   public List<String> getAllPeerIds() {
     List<String> ids = null;
     try {
       ids = ZKUtil.listChildrenAndWatchThem(this.zookeeper, this.peersZNode);
     } catch (KeeperException e) {
       this.abortable.abort("Cannot get the list of peers ", e);
     }
     return ids;
   }
 
   /**
    * A private method used during initialization. This method attempts to add all registered
    * peer clusters. This method does not set a watch on the peer cluster znodes.
    */
   private void addExistingPeers() throws ReplicationException {
     List<String> znodes = null;
     try {
       znodes = ZKUtil.listChildrenNoWatch(this.zookeeper, this.peersZNode);
     } catch (KeeperException e) {
       throw new ReplicationException("Error getting the list of peer clusters.", e);
     }
     if (znodes != null) {
       for (String z : znodes) {
         createAndAddPeer(z);
       }
     }
   }
 
   @Override
   public boolean peerAdded(String peerId) throws ReplicationException {
     return createAndAddPeer(peerId);
   }
 
   @Override
   public void peerRemoved(String peerId) {
     ReplicationPeer rp = this.peerClusters.get(peerId);
     if (rp != null) {
       ((ConcurrentMap<String, ReplicationPeerZKImpl>) peerClusters).remove(peerId, rp);
     }
   }
 
   /**
    * Attempt to connect to a new remote slave cluster.
    * @param peerId a short that identifies the cluster
    * @return true if a new connection was made, false if no new connection was made.
    */
   public boolean createAndAddPeer(String peerId) throws ReplicationException {
     if (peerClusters == null) {
       return false;
     }
     if (this.peerClusters.containsKey(peerId)) {
       return false;
     }
 
     ReplicationPeerZKImpl peer = null;
     try {
       peer = createPeer(peerId);
     } catch (Exception e) {
       throw new ReplicationException("Error adding peer with id=" + peerId, e);
     }
     if (peer == null) {
       return false;
     }
     ReplicationPeerZKImpl previous =
       ((ConcurrentMap<String, ReplicationPeerZKImpl>) peerClusters).putIfAbsent(peerId, peer);
     if (previous == null) {
       LOG.info("Added new peer cluster=" + peer.getPeerConfig().getClusterKey());
     } else {
       LOG.info("Peer already present, " + previous.getPeerConfig().getClusterKey() +
         ", new cluster=" + peer.getPeerConfig().getClusterKey());
     }
     return true;
   }
 
   private String getTableCFsNode(String id) {
     return ZKUtil.joinZNode(this.peersZNode, ZKUtil.joinZNode(id, this.tableCFsNodeName));
   }
 
   private String getPeerStateNode(String id) {
     return ZKUtil.joinZNode(this.peersZNode, ZKUtil.joinZNode(id, this.peerStateNodeName));
   }
 
   /**
    * Update the state znode of a peer cluster.
    * @param id
    * @param state
    */
   private void changePeerState(String id, ZooKeeperProtos.ReplicationState.State state)
       throws ReplicationException {
     try {
       if (!peerExists(id)) {
         throw new IllegalArgumentException("Cannot enable/disable peer because id=" + id
             + " does not exist.");
       }
       String peerStateZNode = getPeerStateNode(id);
       byte[] stateBytes =
           (state == ZooKeeperProtos.ReplicationState.State.ENABLED) ? ENABLED_ZNODE_BYTES
               : DISABLED_ZNODE_BYTES;
       if (ZKUtil.checkExists(this.zookeeper, peerStateZNode) != -1) {
         ZKUtil.setData(this.zookeeper, peerStateZNode, stateBytes);
       } else {
         ZKUtil.createAndWatch(this.zookeeper, peerStateZNode, stateBytes);
       }
       LOG.info("Peer with id= " + id + " is now " + state.name());
     } catch (KeeperException e) {
       throw new ReplicationException("Unable to change state of the peer with id=" + id, e);
     }
   }
 
   /**
    * Helper method to connect to a peer
    * @param peerId peer's identifier
    * @return object representing the peer
    * @throws ReplicationException
    */
   private ReplicationPeerZKImpl createPeer(String peerId) throws ReplicationException {
     Pair<ReplicationPeerConfig, Configuration> pair = getPeerConf(peerId);
     if (pair == null) {
       return null;
     }
     Configuration peerConf = pair.getSecond();
 
     ReplicationPeerZKImpl peer = new ReplicationPeerZKImpl(peerConf, peerId, pair.getFirst());
     try {
       peer.startStateTracker(this.zookeeper, this.getPeerStateNode(peerId));
     } catch (KeeperException e) {
       throw new ReplicationException("Error starting the peer state tracker for peerId=" +
           peerId, e);
     }
 
     try {
       peer.startTableCFsTracker(this.zookeeper, this.getTableCFsNode(peerId));
     } catch (KeeperException e) {
       throw new ReplicationException("Error starting the peer tableCFs tracker for peerId=" +
           peerId, e);
     }
 
     return peer;
   }
 
   /**
    * @param bytes Content of a peer znode.
    * @return ClusterKey parsed from the passed bytes.
    * @throws DeserializationException
    */
   private static ReplicationPeerConfig parsePeerFrom(final byte[] bytes)
       throws DeserializationException {
     if (ProtobufUtil.isPBMagicPrefix(bytes)) {
       int pblen = ProtobufUtil.lengthOfPBMagic();
       ZooKeeperProtos.ReplicationPeer.Builder builder =
           ZooKeeperProtos.ReplicationPeer.newBuilder();
       ZooKeeperProtos.ReplicationPeer peer;
       try {
         ProtobufUtil.mergeFrom(builder, bytes, pblen, bytes.length - pblen);
         peer = builder.build();
       } catch (IOException e) {
         throw new DeserializationException(e);
       }
       return convert(peer);
     } else {
       if (bytes.length > 0) {
         return new ReplicationPeerConfig().setClusterKey(Bytes.toString(bytes));
       }
       return new ReplicationPeerConfig().setClusterKey("");
     }
   }
 
   private static ReplicationPeerConfig convert(ZooKeeperProtos.ReplicationPeer peer) {
     ReplicationPeerConfig peerConfig = new ReplicationPeerConfig();
     if (peer.hasClusterkey()) {
       peerConfig.setClusterKey(peer.getClusterkey());
     }
     if (peer.hasReplicationEndpointImpl()) {
       peerConfig.setReplicationEndpointImpl(peer.getReplicationEndpointImpl());
     }
 
     for (BytesBytesPair pair : peer.getDataList()) {
       peerConfig.getPeerData().put(pair.getFirst().toByteArray(), pair.getSecond().toByteArray());
     }
 
     for (NameStringPair pair : peer.getConfigurationList()) {
       peerConfig.getConfiguration().put(pair.getName(), pair.getValue());
     }
     return peerConfig;
   }
 
   private static ZooKeeperProtos.ReplicationPeer convert(ReplicationPeerConfig  peerConfig) {
     ZooKeeperProtos.ReplicationPeer.Builder builder = ZooKeeperProtos.ReplicationPeer.newBuilder();
     if (peerConfig.getClusterKey() != null) {
       builder.setClusterkey(peerConfig.getClusterKey());
     }
     if (peerConfig.getReplicationEndpointImpl() != null) {
       builder.setReplicationEndpointImpl(peerConfig.getReplicationEndpointImpl());
     }
 
     for (Map.Entry<byte[], byte[]> entry : peerConfig.getPeerData().entrySet()) {
       builder.addData(BytesBytesPair.newBuilder()
         .setFirst(ByteString.copyFrom(entry.getKey()))
         .setSecond(ByteString.copyFrom(entry.getValue()))
           .build());
     }
 
     for (Map.Entry<String, String> entry : peerConfig.getConfiguration().entrySet()) {
       builder.addConfiguration(NameStringPair.newBuilder()
         .setName(entry.getKey())
         .setValue(entry.getValue())
         .build());
     }
 
     return builder.build();
   }
 
   /**
    * @param peerConfig
    * @return Serialized protobuf of <code>peerConfig</code> with pb magic prefix prepended suitable
    *         for use as content of a this.peersZNode; i.e. the content of PEER_ID znode under
    *         /hbase/replication/peers/PEER_ID
    */
   private static byte[] toByteArray(final ReplicationPeerConfig peerConfig) {
     byte[] bytes = convert(peerConfig).toByteArray();
     return ProtobufUtil.prependPBMagic(bytes);
   }
 
 }