/**
    *
    * 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.mapreduce;
  
  import java.io.IOException;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.classification.InterfaceStability;
  import org.apache.hadoop.conf.Configurable;
  import org.apache.hadoop.conf.Configuration;
  import org.apache.hadoop.hbase.HBaseConfiguration;
  import org.apache.hadoop.hbase.HConstants;
  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.HTable;
  import org.apache.hadoop.hbase.client.Mutation;
  import org.apache.hadoop.hbase.client.Put;
  import org.apache.hadoop.mapreduce.JobContext;
  import org.apache.hadoop.mapreduce.OutputCommitter;
  import org.apache.hadoop.mapreduce.OutputFormat;
  import org.apache.hadoop.mapreduce.RecordWriter;
  import org.apache.hadoop.mapreduce.TaskAttemptContext;
  
  /**
   * Convert Map/Reduce output and write it to an HBase table. The KEY is ignored
   * while the output value <u>must</u> be either a {@link Put} or a
   * {@link Delete} instance.
   */
  @InterfaceAudience.Public
  @InterfaceStability.Stable
  public class TableOutputFormat<KEY> extends OutputFormat<KEY, Mutation>
  implements Configurable {
  
    private static final Log LOG = LogFactory.getLog(TableOutputFormat.class);
  
    /** Job parameter that specifies the output table. */
    public static final String OUTPUT_TABLE = "hbase.mapred.outputtable";
  
    /**
     * Prefix for configuration property overrides to apply in {@link #setConf(Configuration)}.
     * For keys matching this prefix, the prefix is stripped, and the value is set in the
     * configuration with the resulting key, ie. the entry "hbase.mapred.output.key1 = value1"
     * would be set in the configuration as "key1 = value1".  Use this to set properties
     * which should only be applied to the {@code TableOutputFormat} configuration and not the
     * input configuration.
     */
    public static final String OUTPUT_CONF_PREFIX = "hbase.mapred.output.";
  
    /**
     * Optional job parameter to specify a peer cluster.
     * Used specifying remote cluster when copying between hbase clusters (the
     * source is picked up from <code>hbase-site.xml</code>).
     * @see TableMapReduceUtil#initTableReducerJob(String, Class, org.apache.hadoop.mapreduce.Job, Class, String, String, String)
     */
    public static final String QUORUM_ADDRESS = OUTPUT_CONF_PREFIX + "quorum";
  
    /** Optional job parameter to specify peer cluster's ZK client port */
    public static final String QUORUM_PORT = OUTPUT_CONF_PREFIX + "quorum.port";
  
    /** Optional specification of the rs class name of the peer cluster */
    public static final String
        REGION_SERVER_CLASS = OUTPUT_CONF_PREFIX + "rs.class";
    /** Optional specification of the rs impl name of the peer cluster */
    public static final String
        REGION_SERVER_IMPL = OUTPUT_CONF_PREFIX + "rs.impl";
  
    /** The configuration. */
    private Configuration conf = null;
  
    /**
     * Writes the reducer output to an HBase table.
     */
    protected class TableRecordWriter
    extends RecordWriter<KEY, Mutation> {
  
      private Connection connection;
      private BufferedMutator mutator;
  
     /**
      * @throws IOException 
      * 
      */
     public TableRecordWriter() throws IOException {
       String tableName = conf.get(OUTPUT_TABLE);
       this.connection = ConnectionFactory.createConnection(conf);
       this.mutator = connection.getBufferedMutator(TableName.valueOf(tableName));
       LOG.info("Created table instance for "  + tableName);
     }
     /**
      * Closes the writer, in this case flush table commits.
      *
      * @param context  The context.
      * @throws IOException When closing the writer fails.
      * @see RecordWriter#close(TaskAttemptContext)
      */
     @Override
     public void close(TaskAttemptContext context) throws IOException {
       try {
         if (mutator != null) {
           mutator.close();
         }
       } finally {
         if (connection != null) {
           connection.close();
         }
       }
     }
 
     /**
      * Writes a key/value pair into the table.
      *
      * @param key  The key.
      * @param value  The value.
      * @throws IOException When writing fails.
      * @see RecordWriter#write(Object, Object)
      */
     @Override
     public void write(KEY key, Mutation value)
     throws IOException {
       if (!(value instanceof Put) && !(value instanceof Delete)) {
         throw new IOException("Pass a Delete or a Put");
       }
       mutator.mutate(value);
     }
   }
 
   /**
    * Creates a new record writer.
    *
    * @param context  The current task context.
    * @return The newly created writer instance.
    * @throws IOException When creating the writer fails.
    * @throws InterruptedException When the jobs is cancelled.
    */
   @Override
   public RecordWriter<KEY, Mutation> getRecordWriter(TaskAttemptContext context)
   throws IOException, InterruptedException {
     return new TableRecordWriter();
   }
 
   /**
    * Checks if the output target exists.
    *
    * @param context  The current context.
    * @throws IOException When the check fails.
    * @throws InterruptedException When the job is aborted.
    * @see OutputFormat#checkOutputSpecs(JobContext)
    */
   @Override
   public void checkOutputSpecs(JobContext context) throws IOException,
       InterruptedException {
     // TODO Check if the table exists?
 
   }
 
   /**
    * Returns the output committer.
    *
    * @param context  The current context.
    * @return The committer.
    * @throws IOException When creating the committer fails.
    * @throws InterruptedException When the job is aborted.
    * @see OutputFormat#getOutputCommitter(TaskAttemptContext)
    */
   @Override
   public OutputCommitter getOutputCommitter(TaskAttemptContext context)
   throws IOException, InterruptedException {
     return new TableOutputCommitter();
   }
 
   @Override
   public Configuration getConf() {
     return conf;
   }
 
   @Override
   public void setConf(Configuration otherConf) {
     String tableName = otherConf.get(OUTPUT_TABLE);
     if(tableName == null || tableName.length() <= 0) {
       throw new IllegalArgumentException("Must specify table name");
     }
 
     String address = otherConf.get(QUORUM_ADDRESS);
     int zkClientPort = otherConf.getInt(QUORUM_PORT, 0);
     String serverClass = otherConf.get(REGION_SERVER_CLASS);
     String serverImpl = otherConf.get(REGION_SERVER_IMPL);
 
     try {
       this.conf = HBaseConfiguration.createClusterConf(otherConf, address, OUTPUT_CONF_PREFIX);
 
       if (serverClass != null) {
         this.conf.set(HConstants.REGION_SERVER_IMPL, serverImpl);
       }
       if (zkClientPort != 0) {
         this.conf.setInt(HConstants.ZOOKEEPER_CLIENT_PORT, zkClientPort);
       }
     } catch(IOException e) {
       LOG.error(e);
       throw new RuntimeException(e);
     }
   }
 }