/*

  * 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.giraph.io.hcatalog;

 import org.apache.giraph.io.VertexValueInputFormat;

 import org.apache.giraph.io.VertexValueReader;

 import org.apache.hadoop.io.Writable;

 import org.apache.hadoop.io.WritableComparable;

 import org.apache.hadoop.mapreduce.InputSplit;

 import org.apache.hadoop.mapreduce.JobContext;

 import org.apache.hadoop.mapreduce.RecordReader;

 import org.apache.hadoop.mapreduce.TaskAttemptContext;

 import org.apache.hcatalog.data.HCatRecord;

 import java.io.IOException;

 import java.util.List;

 /**

  * HCatalog {@link VertexValueInputFormat} for reading vertex values from

  * Hive/Pig.

  *

  * @param <I> Vertex id

  * @param <V> Vertex value

  */

 public abstract class HCatalogVertexValueInputFormat<I extends

     WritableComparable, V extends Writable>

     extends VertexValueInputFormat<I, V> {

   /**

    * HCatalog input format.

    */

   private GiraphHCatInputFormat hCatInputFormat = new GiraphHCatInputFormat();

   @Override

   public List<InputSplit> getSplits(JobContext context, int minSplitCountHint)

     throws IOException, InterruptedException {

     return hCatInputFormat.getVertexSplits(context);

   }

   /**

    * {@link VertexValueReader} for {@link HCatalogVertexValueInputFormat}.

    */

   protected abstract class HCatalogVertexValueReader

       extends VertexValueReader<I, V> {

     /** Internal {@link RecordReader}. */

     private RecordReader<WritableComparable, HCatRecord> hCatRecordReader;

     /** Context passed to initialize. */

     private TaskAttemptContext context;

     @Override

     public final void initialize(InputSplit inputSplit,

                                  TaskAttemptContext context)

       throws IOException, InterruptedException {

       super.initialize(inputSplit, context);

       hCatRecordReader =

           hCatInputFormat.createVertexRecordReader(inputSplit, context);

       hCatRecordReader.initialize(inputSplit, context);

       this.context = context;

     }

     @Override

     public boolean nextVertex() throws IOException, InterruptedException {

       return hCatRecordReader.nextKeyValue();

     }

     @Override

     public final void close() throws IOException {

       hCatRecordReader.close();

     }

     @Override

     public final float getProgress() throws IOException, InterruptedException {

       return hCatRecordReader.getProgress();

     }

     /**

      * Get the record reader.

      *

      * @return Record reader to be used for reading.

      */

     protected final RecordReader<WritableComparable, HCatRecord>

     getRecordReader() {

       return hCatRecordReader;

     }

     /**

      * Get the context.

      *

      * @return Context passed to initialize.

      */

     protected final TaskAttemptContext getContext() {

       return context;

     }

   }

   /**

    * Create {@link VertexValueReader}.

    * @return {@link HCatalogVertexValueReader} instance.

    */

   protected abstract HCatalogVertexValueReader createVertexValueReader();

   @Override

   public final VertexValueReader<I, V>

   createVertexValueReader(InputSplit split, TaskAttemptContext context)

     throws IOException {

     try {

       HCatalogVertexValueReader reader = createVertexValueReader();

       reader.initialize(split, context);

       return reader;

     } catch (InterruptedException e) {

       throw new IllegalStateException(

           "createVertexValueReader: Interrupted creating reader.", e);

     }

   }

   /**

    * {@link HCatalogVertexValueReader} for tables holding a complete vertex

    * value in each row.

    */

   protected abstract class SingleRowHCatalogVertexValueReader

       extends HCatalogVertexValueReader {

     /**

      * Get vertex id from a record.

      *

      * @param record Input record

      * @return I Vertex id

      */

     protected abstract I getVertexId(HCatRecord record);

     /**

      * Get vertex value from a record.

      *

      * @param record Input record

      * @return V Vertex value

      */

     protected abstract V getVertexValue(HCatRecord record);

     @Override

     public final I getCurrentVertexId() throws IOException,

         InterruptedException {

       return getVertexId(getRecordReader().getCurrentValue());

     }

     @Override

     public final V getCurrentVertexValue() throws IOException,

         InterruptedException {

       return getVertexValue(getRecordReader().getCurrentValue());

     }

   }

 }