/**
    * 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.mapred;
  
  import org.apache.hadoop.fs.Path;
  import org.apache.hadoop.hbase.HRegionInfo;
  import org.apache.hadoop.hbase.HTableDescriptor;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.classification.InterfaceStability;
  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.hbase.mapreduce.TableSnapshotInputFormatImpl;
  import org.apache.hadoop.hbase.util.RegionSplitter;
  import org.apache.hadoop.mapred.InputFormat;
  import org.apache.hadoop.mapred.InputSplit;
  import org.apache.hadoop.mapred.JobConf;
  import org.apache.hadoop.mapred.RecordReader;
  import org.apache.hadoop.mapred.Reporter;
  import org.apache.hadoop.mapreduce.Job;
  
  import java.io.DataInput;
  import java.io.DataOutput;
  import java.io.IOException;
  import java.util.List;
  
  /**
   * TableSnapshotInputFormat allows a MapReduce job to run over a table snapshot. Further
   * documentation available on {@link org.apache.hadoop.hbase.mapreduce.TableSnapshotInputFormat}.
   *
   * @see org.apache.hadoop.hbase.mapreduce.TableSnapshotInputFormat
   */
  @InterfaceAudience.Public
  @InterfaceStability.Evolving
  public class TableSnapshotInputFormat implements InputFormat<ImmutableBytesWritable, Result> {
  
    public static class TableSnapshotRegionSplit implements InputSplit {
      private TableSnapshotInputFormatImpl.InputSplit delegate;
  
      // constructor for mapreduce framework / Writable
      public TableSnapshotRegionSplit() {
        this.delegate = new TableSnapshotInputFormatImpl.InputSplit();
      }
  
      public TableSnapshotRegionSplit(TableSnapshotInputFormatImpl.InputSplit delegate) {
        this.delegate = delegate;
      }
  
      public TableSnapshotRegionSplit(HTableDescriptor htd, HRegionInfo regionInfo,
          List<String> locations, Scan scan, Path restoreDir) {
        this.delegate =
            new TableSnapshotInputFormatImpl.InputSplit(htd, regionInfo, locations, scan, restoreDir);
      }
  
      @Override
      public long getLength() throws IOException {
        return delegate.getLength();
      }
  
      @Override
      public String[] getLocations() throws IOException {
        return delegate.getLocations();
      }
  
      @Override
      public void write(DataOutput out) throws IOException {
        delegate.write(out);
      }
  
      @Override
      public void readFields(DataInput in) throws IOException {
        delegate.readFields(in);
      }
    }
  
    static class TableSnapshotRecordReader
      implements RecordReader<ImmutableBytesWritable, Result> {
  
      private TableSnapshotInputFormatImpl.RecordReader delegate;
  
      public TableSnapshotRecordReader(TableSnapshotRegionSplit split, JobConf job)
          throws IOException {
        delegate = new TableSnapshotInputFormatImpl.RecordReader();
       delegate.initialize(split.delegate, job);
     }
 
     @Override
     public boolean next(ImmutableBytesWritable key, Result value) throws IOException {
       if (!delegate.nextKeyValue()) {
         return false;
       }
       ImmutableBytesWritable currentKey = delegate.getCurrentKey();
       key.set(currentKey.get(), currentKey.getOffset(), currentKey.getLength());
       value.copyFrom(delegate.getCurrentValue());
       return true;
     }
 
     @Override
     public ImmutableBytesWritable createKey() {
       return new ImmutableBytesWritable();
     }
 
     @Override
     public Result createValue() {
       return new Result();
     }
 
     @Override
     public long getPos() throws IOException {
       return delegate.getPos();
     }
 
     @Override
     public void close() throws IOException {
       delegate.close();
     }
 
     @Override
     public float getProgress() throws IOException {
       return delegate.getProgress();
     }
   }
 
   @Override
   public InputSplit[] getSplits(JobConf job, int numSplits) throws IOException {
     List<TableSnapshotInputFormatImpl.InputSplit> splits =
       TableSnapshotInputFormatImpl.getSplits(job);
     InputSplit[] results = new InputSplit[splits.size()];
     for (int i = 0; i < splits.size(); i++) {
       results[i] = new TableSnapshotRegionSplit(splits.get(i));
     }
     return results;
   }
 
   @Override
   public RecordReader<ImmutableBytesWritable, Result>
   getRecordReader(InputSplit split, JobConf job, Reporter reporter) throws IOException {
     return new TableSnapshotRecordReader((TableSnapshotRegionSplit) split, job);
   }
 
   /**
    * Configures the job to use TableSnapshotInputFormat to read from a snapshot.
    * @param job the job to configure
    * @param snapshotName the name of the snapshot to read from
    * @param restoreDir a temporary directory to restore the snapshot into. Current user should
    * have write permissions to this directory, and this should not be a subdirectory of rootdir.
    * After the job is finished, restoreDir can be deleted.
    * @throws IOException if an error occurs
    */
   public static void setInput(JobConf job, String snapshotName, Path restoreDir)
       throws IOException {
     TableSnapshotInputFormatImpl.setInput(job, snapshotName, restoreDir);
   }
 
   /**
    * Configures the job to use TableSnapshotInputFormat to read from a snapshot.
    * @param job the job to configure
    * @param snapshotName the name of the snapshot to read from
    * @param restoreDir a temporary directory to restore the snapshot into. Current user should
    * have write permissions to this directory, and this should not be a subdirectory of rootdir.
    * After the job is finished, restoreDir can be deleted.
    * @param splitAlgo split algorithm to generate splits from region
    * @param numSplitsPerRegion how many input splits to generate per one region
    * @throws IOException if an error occurs
    */
   public static void setInput(JobConf job, String snapshotName, Path restoreDir,
                               RegionSplitter.SplitAlgorithm splitAlgo, int numSplitsPerRegion) throws IOException {
     TableSnapshotInputFormatImpl.setInput(job, snapshotName, restoreDir, splitAlgo, numSplitsPerRegion);
   }
 }