/*

  * 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.formats;

 import java.io.IOException;

 import org.apache.giraph.graph.Vertex;

 import org.apache.hadoop.io.Text;

 import org.apache.hadoop.io.Writable;

 import org.apache.hadoop.io.WritableComparable;

 import org.apache.hadoop.mapreduce.TaskAttemptContext;

 /**

  * 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> {

   /** 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;

   @Override

   public TextVertexWriter createVertexWriter(TaskAttemptContext context) {

     return new IdWithValueVertexWriter();

   }

   /**

    * Vertex writer used with {@link IdWithValueTextOutputFormat}.

    */

   protected class IdWithValueVertexWriter extends TextVertexWriterToEachLine {

     /** Saved delimiter */

     private String delimiter;

     /** Cached reserve option */

     private boolean reverseOutput;

     @Override

     public void initialize(TaskAttemptContext context) throws IOException,

         InterruptedException {

       super.initialize(context);

       delimiter = getConf().get(

           LINE_TOKENIZE_VALUE, LINE_TOKENIZE_VALUE_DEFAULT);

       reverseOutput = getConf().getBoolean(

           REVERSE_ID_AND_VALUE, REVERSE_ID_AND_VALUE_DEFAULT);

     }

     @Override

     protected Text convertVertexToLine(Vertex<I, V, E> vertex)

       throws IOException {

       StringBuilder str = new StringBuilder();

       if (reverseOutput) {

         str.append(vertex.getValue().toString());

         str.append(delimiter);

         str.append(vertex.getId().toString());

       } else {

         str.append(vertex.getId().toString());

         str.append(delimiter);

         str.append(vertex.getValue().toString());

       }

       return new Text(str.toString());

     }

   }

 }