/**
    *
    * 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.master.handler;
  
  import java.io.IOException;
  import java.util.HashSet;
  import java.util.List;
  import java.util.Set;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.hbase.HConstants;
  import org.apache.hadoop.hbase.HRegionInfo;
  import org.apache.hadoop.hbase.HTableDescriptor;
  import org.apache.hadoop.hbase.MetaTableAccessor;
  import org.apache.hadoop.hbase.Server;
  import org.apache.hadoop.hbase.TableName;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.client.Connection;
  import org.apache.hadoop.hbase.client.Result;
  import org.apache.hadoop.hbase.client.ResultScanner;
  import org.apache.hadoop.hbase.client.Scan;
  import org.apache.hadoop.hbase.client.Table;
  import org.apache.hadoop.hbase.executor.EventType;
  import org.apache.hadoop.hbase.master.HMaster;
  import org.apache.hadoop.hbase.master.MasterCoprocessorHost;
  import org.apache.hadoop.hbase.master.MasterFileSystem;
  import org.apache.hadoop.hbase.master.MasterServices;
  import org.apache.hadoop.hbase.protobuf.generated.ZooKeeperProtos;
  import org.apache.hadoop.hbase.util.Bytes;
  import org.apache.hadoop.hbase.util.ServerRegionReplicaUtil;
  
  @InterfaceAudience.Private
  public class ModifyTableHandler extends TableEventHandler {
    private static final Log LOG = LogFactory.getLog(ModifyTableHandler.class);
  
    private final HTableDescriptor htd;
  
    public ModifyTableHandler(final TableName tableName,
        final HTableDescriptor htd, final Server server,
        final MasterServices masterServices) {
      super(EventType.C_M_MODIFY_TABLE, tableName, server, masterServices);
      // This is the new schema we are going to write out as this modification.
      this.htd = htd;
    }
  
    @Override
    protected void prepareWithTableLock() throws IOException {
      super.prepareWithTableLock();
      // Check operation is possible on the table in its current state
      // Also checks whether the table exists
      if (masterServices.getAssignmentManager().getTableStateManager()
          .isTableState(this.htd.getTableName(), ZooKeeperProtos.Table.State.ENABLED)
          && this.htd.getRegionReplication() != getTableDescriptor().getRegionReplication()) {
        throw new IOException("REGION_REPLICATION change is not supported for enabled tables");
      }
    }
  
    @Override
    protected void handleTableOperation(List<HRegionInfo> hris)
    throws IOException {
      MasterCoprocessorHost cpHost = ((HMaster) this.server).getMasterCoprocessorHost();
      if (cpHost != null) {
        cpHost.preModifyTableHandler(this.tableName, this.htd);
      }
      // Update descriptor
      HTableDescriptor oldHtd = getTableDescriptor();
      this.masterServices.getTableDescriptors().add(this.htd);
      deleteFamilyFromFS(hris, oldHtd.getFamiliesKeys());
      removeReplicaColumnsIfNeeded(this.htd.getRegionReplication(), oldHtd.getRegionReplication(),
          htd.getTableName());
      // Setup replication for region replicas if needed
      if (htd.getRegionReplication() > 1 && oldHtd.getRegionReplication() <= 1) {
        ServerRegionReplicaUtil.setupRegionReplicaReplication(server.getConfiguration());
      }
      if (cpHost != null) {
        cpHost.postModifyTableHandler(this.tableName, this.htd);
      }
    }
  
    private void removeReplicaColumnsIfNeeded(int newReplicaCount, int oldReplicaCount,
        TableName table) throws IOException {
      if (newReplicaCount >= oldReplicaCount) return;
     Set<byte[]> tableRows = new HashSet<byte[]>();
     Scan scan = MetaTableAccessor.getScanForTableName(table);
     scan.addColumn(HConstants.CATALOG_FAMILY, HConstants.REGIONINFO_QUALIFIER);
     Connection connection = this.masterServices.getConnection();
     try (Table metaTable = connection.getTable(TableName.META_TABLE_NAME)) {
       ResultScanner resScanner = metaTable.getScanner(scan);
       for (Result result : resScanner) {
         tableRows.add(result.getRow());
       }
       MetaTableAccessor.removeRegionReplicasFromMeta(tableRows, newReplicaCount,
         oldReplicaCount - newReplicaCount, masterServices.getConnection());
     }
   }
 
   /**
    * Removes from hdfs the families that are not longer present in the new table descriptor.
    */
   private void deleteFamilyFromFS(final List<HRegionInfo> hris, final Set<byte[]> oldFamilies) {
     try {
       Set<byte[]> newFamilies = this.htd.getFamiliesKeys();
       MasterFileSystem mfs = this.masterServices.getMasterFileSystem();
       for (byte[] familyName: oldFamilies) {
         if (!newFamilies.contains(familyName)) {
           LOG.debug("Removing family=" + Bytes.toString(familyName) +
                     " from table=" + this.tableName);
           for (HRegionInfo hri: hris) {
             // Delete the family directory in FS for all the regions one by one
             mfs.deleteFamilyFromFS(hri, familyName);
           }
         }
       }
     } catch (IOException e) {
       LOG.warn("Unable to remove on-disk directories for the removed families", e);
     }
   }
 
   @Override
   public String toString() {
     String name = "UnknownServerName";
     if(server != null && server.getServerName() != null) {
       name = server.getServerName().toString();
     }
     return getClass().getSimpleName() + "-" + name + "-" + getSeqid() + "-" +
       tableName;
   }
 }