/**
 *
 * 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.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.hbase.client.HTable;
import org.apache.hadoop.hbase.client.Result;
import org.apache.hadoop.hbase.client.Scan;
import org.apache.hadoop.hbase.io.ImmutableBytesWritable;
import org.apache.hadoop.mapreduce.InputSplit;
import org.apache.hadoop.mapreduce.RecordReader;
import org.apache.hadoop.mapreduce.TaskAttemptContext;

/**
 * Iterate over an HBase table data, return (ImmutableBytesWritable, Result)
 * pairs.
 */
@InterfaceAudience.Public
@InterfaceStability.Stable
public class TableRecordReader
extends RecordReader<ImmutableBytesWritable, Result> {

  private TableRecordReaderImpl recordReaderImpl = new TableRecordReaderImpl();

  /**
   * Restart from survivable exceptions by creating a new scanner.
   *
   * @param firstRow  The first row to start at.
   * @throws IOException When restarting fails.
   */
  public void restart(byte[] firstRow) throws IOException {
    this.recordReaderImpl.restart(firstRow);
  }


  /**
   * Sets the HBase table.
   *
   * @param htable  The {@link HTable} to scan.
   */
  public void setHTable(HTable htable) {
    this.recordReaderImpl.setHTable(htable);
  }

  /**
   * Sets the scan defining the actual details like columns etc.
   *
   * @param scan  The scan to set.
   */
  public void setScan(Scan scan) {
    this.recordReaderImpl.setScan(scan);
  }

  /**
   * Closes the split.
   *
   * @see org.apache.hadoop.mapreduce.RecordReader#close()
   */
  @Override
  public void close() {
    this.recordReaderImpl.close();
  }

  /**
   * Returns the current key.
   *
   * @return The current key.
   * @throws IOException
   * @throws InterruptedException When the job is aborted.
   * @see org.apache.hadoop.mapreduce.RecordReader#getCurrentKey()
   */
  @Override
  public ImmutableBytesWritable getCurrentKey() throws IOException,
      InterruptedException {
    return this.recordReaderImpl.getCurrentKey();
  }

  /**
   * Returns the current value.
   *
   * @return The current value.
   * @throws IOException When the value is faulty.
   * @throws InterruptedException When the job is aborted.
   * @see org.apache.hadoop.mapreduce.RecordReader#getCurrentValue()
   */
  @Override
  public Result getCurrentValue() throws IOException, InterruptedException {
    return this.recordReaderImpl.getCurrentValue();
  }

  /**
   * Initializes the reader.
   *
   * @param inputsplit  The split to work with.
   * @param context  The current task context.
   * @throws IOException When setting up the reader fails.
   * @throws InterruptedException When the job is aborted.
   * @see org.apache.hadoop.mapreduce.RecordReader#initialize(
   *   org.apache.hadoop.mapreduce.InputSplit,
   *   org.apache.hadoop.mapreduce.TaskAttemptContext)
   */
  @Override
  public void initialize(InputSplit inputsplit,
      TaskAttemptContext context) throws IOException,
      InterruptedException {
    this.recordReaderImpl.initialize(inputsplit, context);
  }

  /**
   * Positions the record reader to the next record.
   *
   * @return <code>true</code> if there was another record.
   * @throws IOException When reading the record failed.
   * @throws InterruptedException When the job was aborted.
   * @see org.apache.hadoop.mapreduce.RecordReader#nextKeyValue()
   */
  @Override
  public boolean nextKeyValue() throws IOException, InterruptedException {
    return this.recordReaderImpl.nextKeyValue();
  }

  /**
   * The current progress of the record reader through its data.
   *
   * @return A number between 0.0 and 1.0, the fraction of the data read.
   * @see org.apache.hadoop.mapreduce.RecordReader#getProgress()
   */
  @Override
  public float getProgress() {
    return this.recordReaderImpl.getProgress();
  }
}
