/*

  * 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.lib;

 import org.apache.giraph.graph.BasicVertex;

 import org.apache.giraph.graph.VertexWriter;

 import org.apache.hadoop.io.Text;

 import org.apache.hadoop.io.Writable;

 import org.apache.hadoop.io.WritableComparable;

 import org.apache.hadoop.mapreduce.RecordWriter;

 import org.apache.hadoop.mapreduce.TaskAttemptContext;

 import java.io.IOException;

 /**

  * Write out Vertices' IDs and values, but not their edges nor edges' values.

  * This is a useful output format when the final value of the vertex is

  * all that's needed. The boolean configuration parameter reverse.id.and.value

  * allows reversing the output of id and value.

  *

  * @param <I> Vertex index value

  * @param <V> Vertex value

  * @param <E> Edge value

  */

 @SuppressWarnings("rawtypes")

 public class IdWithValueTextOutputFormat<I extends WritableComparable,

     V extends Writable, E extends Writable>

     extends TextVertexOutputFormat<I, V, E> {

   /**

    * Vertex writer used with {@link IdWithValueTextOutputFormat}.

    *

    * @param <I> Vertex id

    * @param <V> Vertex data

    * @param <E> Edge data

    */

   static class IdWithValueVertexWriter<I extends WritableComparable, V extends

       Writable, E extends Writable> extends TextVertexWriter<I, V, E> {

     /** Specify the output delimiter */

     public static final String LINE_TOKENIZE_VALUE = "output.delimiter";

     /** Default output delimiter */

     public static final String LINE_TOKENIZE_VALUE_DEFAULT = "\t";

     /** Reverse id and value order? */

     public static final String REVERSE_ID_AND_VALUE = "reverse.id.and.value";

     /** Default is to not reverse id and value order. */

     public static final boolean REVERSE_ID_AND_VALUE_DEFAULT = false;

     /** Saved delimiter */

     private String delimiter;

     /**

      * Constructor with record writer.

      *

      * @param recordWriter Writer from LineRecordWriter.

      */

     public IdWithValueVertexWriter(RecordWriter<Text, Text> recordWriter) {

       super(recordWriter);

     }

     @Override

     public void writeVertex(BasicVertex<I, V, E, ?> vertex) throws IOException,

     InterruptedException {

       if (delimiter == null) {

         delimiter = getContext().getConfiguration()

             .get(LINE_TOKENIZE_VALUE, LINE_TOKENIZE_VALUE_DEFAULT);

       }

       String first;

       String second;

       boolean reverseOutput = getContext().getConfiguration()

           .getBoolean(REVERSE_ID_AND_VALUE, REVERSE_ID_AND_VALUE_DEFAULT);

       if (reverseOutput) {

         first = vertex.getVertexValue().toString();

         second = vertex.getVertexId().toString();

       } else {

         first = vertex.getVertexId().toString();

         second = vertex.getVertexValue().toString();

       }

       Text line = new Text(first + delimiter + second);

       getRecordWriter().write(line, null);

     }

   }

   @Override

   public VertexWriter<I, V, E> createVertexWriter(TaskAttemptContext context)

     throws IOException, InterruptedException {

     return new IdWithValueVertexWriter<I, V, E>

     (textOutputFormat.getRecordWriter(context));

   }

 }