/**
 * 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.sqoop.hbase;

import org.apache.sqoop.lib.FieldMapProcessor;
import org.apache.sqoop.lib.FieldMappable;
import org.apache.sqoop.lib.ProcessingException;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configurable;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.TableName;
import org.apache.hadoop.hbase.client.BufferedMutator;
import org.apache.hadoop.hbase.client.Connection;
import org.apache.hadoop.hbase.client.ConnectionFactory;
import org.apache.hadoop.hbase.client.Delete;
import org.apache.hadoop.hbase.client.Mutation;
import org.apache.hadoop.hbase.client.Put;
import org.apache.hadoop.hbase.util.Bytes;
import org.apache.hadoop.util.ReflectionUtils;

import java.io.Closeable;
import java.io.IOException;
import java.util.List;
import java.util.Map;

/**
 * SqoopRecordProcessor that performs an HBase "put" operation
 * that contains all the fields of the record.
 */
public class HBasePutProcessor implements Closeable, Configurable,
    FieldMapProcessor {

  public static final Log LOG = LogFactory.getLog(
      HBasePutProcessor.class.getName());

  /** Configuration key specifying the table to insert into. */
  public static final String TABLE_NAME_KEY = "sqoop.hbase.insert.table";

  /** Configuration key specifying the column family to insert into. */
  public static final String COL_FAMILY_KEY =
      "sqoop.hbase.insert.column.family";

  /** Configuration key specifying the column of the input whose value
   * should be used as the row id.
   */
  public static final String ROW_KEY_COLUMN_KEY =
      "sqoop.hbase.insert.row.key.column";

  public static final String NULL_INCREMENTAL_MODE = "hbase.null.incremental.mode";

  /**
   * Configuration key specifying the PutTransformer implementation to use.
   */
  public static final String TRANSFORMER_CLASS_KEY =
      "sqoop.hbase.insert.put.transformer.class";

  /**
   *  Configuration key to enable/disable hbase bulkLoad.
   */
  public static final String BULK_LOAD_ENABLED_KEY =
      "sqoop.hbase.bulk.load.enabled";

  /** Configuration key to specify whether to add the row key column into
   *  HBase. Set to false by default.
   */
  public static final String ADD_ROW_KEY = "sqoop.hbase.add.row.key";
  public static final boolean ADD_ROW_KEY_DEFAULT = false;

  private Configuration conf;

  // An object that can transform a map of fieldName->object
  // into a Put command.
  private PutTransformer putTransformer;

  private Connection hbaseConnection;
  private BufferedMutator bufferedMutator;

  public HBasePutProcessor() {
  }

  HBasePutProcessor(Configuration conf, PutTransformer putTransformer, Connection hbaseConnection, BufferedMutator bufferedMutator) {
    this.conf = conf;
    this.putTransformer = putTransformer;
    this.hbaseConnection = hbaseConnection;
    this.bufferedMutator = bufferedMutator;
  }

  @Override
  @SuppressWarnings("unchecked")
  public void setConf(Configuration config) {
    this.conf = config;

    // Get the implementation of PutTransformer to use.
    // By default, we call toString() on every non-null field.
    Class<? extends PutTransformer> xformerClass =
        (Class<? extends PutTransformer>)
        this.conf.getClass(TRANSFORMER_CLASS_KEY, ToStringPutTransformer.class);
    this.putTransformer = (PutTransformer)
        ReflectionUtils.newInstance(xformerClass, this.conf);
    if (null == putTransformer) {
      throw new RuntimeException("Could not instantiate PutTransformer.");
    }
    putTransformer.init(conf);
    initHBaseMutator();
  }

  private void initHBaseMutator() {
    String tableName = conf.get(TABLE_NAME_KEY, null);
    try {
      hbaseConnection = ConnectionFactory.createConnection(conf);
      bufferedMutator = hbaseConnection.getBufferedMutator(TableName.valueOf(tableName));
    } catch (IOException e) {
      if (hbaseConnection != null) {
        try {
          hbaseConnection.close();
        } catch (IOException connCloseException){
          LOG.error("Cannot close HBase connection.", connCloseException);
        }
      }
      throw new RuntimeException("Could not create mutator for HBase table " + tableName, e);
    }
  }

  @Override
  public Configuration getConf() {
    return this.conf;
  }

  @Override
  /**
   * Processes a record by extracting its field map and converting
   * it into a list of Put commands into HBase.
   */
  public void accept(FieldMappable record)
      throws IOException, ProcessingException {
    Map<String, Object> fields = record.getFieldMap();
    List<Mutation> mutationList = putTransformer.getMutationCommand(fields);
    if (mutationList == null) {
      return;
    }
    for (Mutation mutation : mutationList) {
      if (!canAccept(mutation)) {
        continue;
      }
      if (!mutation.isEmpty()) {
        bufferedMutator.mutate(mutation);
      } else {
        logEmptyMutation(mutation);
      }
    }
  }

  private void logEmptyMutation(Mutation mutation) {
    String action = null;
    if (mutation instanceof Put) {
      action = "insert";
    } else if (mutation instanceof Delete) {
      action = "delete";
    }
    LOG.warn("Could not " + action + " row with no columns "
        + "for row-key column: " + Bytes.toString(mutation.getRow()));
  }

  private boolean canAccept(Mutation mutation) {
    return mutation != null && (mutation instanceof Put || mutation instanceof Delete);
  }

  @Override
  /**
   * Closes the HBase table and commits all pending operations.
   */
  public void close() throws IOException {
    try {
      bufferedMutator.flush();
    } finally {
      try {
        bufferedMutator.close();
      } finally {
        try {
          hbaseConnection.close();
        } catch (IOException e) {
          LOG.error("Cannot close HBase connection.", e);
        }
      }
    }
  }

}