/**
    * 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.client;
  
  import java.io.IOException;
  import java.io.InterruptedIOException;
  import java.util.List;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.hbase.HBaseIOException;
  import org.apache.hadoop.hbase.HRegionInfo;
  import org.apache.hadoop.hbase.HRegionLocation;
  import org.apache.hadoop.hbase.RegionLocations;
  import org.apache.hadoop.hbase.ServerName;
  import org.apache.hadoop.hbase.TableName;
  import org.apache.hadoop.hbase.zookeeper.MasterAddressTracker;
  import org.apache.hadoop.hbase.zookeeper.MetaTableLocator;
  import org.apache.hadoop.hbase.zookeeper.ZKClusterId;
  import org.apache.hadoop.hbase.zookeeper.ZKTableStateClientSideReader;
  import org.apache.hadoop.hbase.zookeeper.ZKUtil;
  import org.apache.zookeeper.KeeperException;
  
  /**
   * A cluster registry that stores to zookeeper.
   */
  class ZKConnectionRegistry implements ConnectionRegistry {
    private static final Log LOG = LogFactory.getLog(ZKConnectionRegistry.class);
    // Needs an instance of hci to function.  Set after construct this instance.
    ConnectionManager.HConnectionImplementation hci;
  
    @Override
    public void init(Connection connection) {
      if (!(connection instanceof ConnectionManager.HConnectionImplementation)) {
        throw new RuntimeException("This registry depends on HConnectionImplementation");
      }
      this.hci = (ConnectionManager.HConnectionImplementation)connection;
    }
  
    @Override
    public ServerName getActiveMaster() throws IOException {
      ServerName sn;
      try (ZooKeeperKeepAliveConnection zkw = hci.getKeepAliveZooKeeperWatcher()) {
        sn = MasterAddressTracker.getMasterAddress(zkw);
      } catch (KeeperException e) {
        throw new HBaseIOException(e);
      }
      return sn;
    }
  
    @Override
    public RegionLocations getMetaRegionLocations() throws IOException {
      try (ZooKeeperKeepAliveConnection zkw = hci.getKeepAliveZooKeeperWatcher();) {
        if (LOG.isTraceEnabled()) {
          LOG.trace("Looking up meta region location in ZK," + " connection=" + this);
        }
        List<ServerName> servers = new MetaTableLocator().blockUntilAvailable(zkw, hci.rpcTimeout,
            hci.getConfiguration());
        if (LOG.isTraceEnabled()) {
          if (servers == null) {
            LOG.trace("Looked up meta region location, connection=" + this +
              "; servers = null");
          } else {
            StringBuilder str = new StringBuilder();
            for (ServerName s : servers) {
              str.append(s.toString());
              str.append(" ");
            }
            LOG.trace("Looked up meta region location, connection=" + this +
              "; servers = " + str.toString());
          }
        }
        if (servers == null) return null;
        HRegionLocation[] locs = new HRegionLocation[servers.size()];
        int i = 0;
        for (ServerName server : servers) {
          HRegionInfo h = RegionReplicaUtil.getRegionInfoForReplica(
                  HRegionInfo.FIRST_META_REGIONINFO, i);
          if (server == null) locs[i++] = null;
          else locs[i++] = new HRegionLocation(h, server, 0);
        }
        return new RegionLocations(locs);
      } catch (InterruptedException e) {
        Thread.currentThread().interrupt();
       return null;
     }
   }
 
   private String clusterId = null;
 
   @Override
   public String getClusterId() {
     if (this.clusterId != null) return this.clusterId;
     // No synchronized here, worse case we will retrieve it twice, that's
     //  not an issue.
     try (ZooKeeperKeepAliveConnection zkw = hci.getKeepAliveZooKeeperWatcher()) {
       this.clusterId = ZKClusterId.readClusterIdZNode(zkw);
       if (this.clusterId == null) {
         LOG.info("ClusterId read in ZooKeeper is null");
       }
     } catch (KeeperException | IOException e) {
       LOG.warn("Can't retrieve clusterId from Zookeeper", e);
     }
     return this.clusterId;
   }
 
   @Override
   public boolean isTableOnlineState(TableName tableName, boolean enabled)
   throws IOException {
     ZooKeeperKeepAliveConnection zkw = hci.getKeepAliveZooKeeperWatcher();
     try {
       if (enabled) {
         return ZKTableStateClientSideReader.isEnabledTable(zkw, tableName);
       }
       return ZKTableStateClientSideReader.isDisabledTable(zkw, tableName);
     } catch (KeeperException e) {
       throw new IOException("Enable/Disable failed", e);
     } catch (InterruptedException e) {
       throw new InterruptedIOException();
     } finally {
       zkw.close();
     }
   }
 
   @Override
   public int getCurrentNrHRS() throws IOException {
     try (ZooKeeperKeepAliveConnection zkw = hci.getKeepAliveZooKeeperWatcher()) {
       // We go to zk rather than to master to get count of regions to avoid
       // HTable having a Master dependency.  See HBase-2828
       return ZKUtil.getNumberOfChildren(zkw, zkw.rsZNode);
     } catch (KeeperException ke) {
       throw new IOException("Unexpected ZooKeeper exception", ke);
     }
   }
 
   @Override
   public void close() {
   }
 }