/*

  * 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.edge.Edge;

 import org.apache.hadoop.io.Text;

 import org.apache.hadoop.io.Writable;

 import org.apache.hadoop.io.WritableComparable;

 import org.apache.hadoop.mapreduce.TaskAttemptContext;

 import static org.apache.giraph.conf.GiraphConstants.GIRAPH_TEXT_OUTPUT_FORMAT_SEPARATOR;

 import static org.apache.giraph.conf.GiraphConstants.GIRAPH_TEXT_OUTPUT_FORMAT_REVERSE;

 /**

  * Write out Edge Value with Source and Destination ID, but not the vertex

  * value.

  * This is a demostration output format to show the possibility to separately

  * output edges from vertices.

  *

  * @param <I> Vertex index value

  * @param <V> Vertex value

  * @param <E> Edge value

  */

 @SuppressWarnings("rawtypes")

 public class SrcIdDstIdEdgeValueTextOutputFormat<I extends WritableComparable,

     V extends Writable, E extends Writable>

     extends TextEdgeOutputFormat<I, V, E> {

   @Override

   public TextEdgeWriter createEdgeWriter(TaskAttemptContext context) {

     return new SrcIdDstIdEdgeValueEdgeWriter();

   }

   /**

    * Edge writer used with {@link SrcIdDstIdEdgeValueTextOutputFormat}.

    */

   protected class SrcIdDstIdEdgeValueEdgeWriter<I extends WritableComparable,

     V extends Writable, E extends Writable>

     extends TextEdgeWriterToEachLine<I, V, E> {

     /** Saved delimiter */

     private String delimiter;

     /** Cached reserve option */

     private boolean reverseOutput;

     @Override

     public void initialize(TaskAttemptContext context)

       throws IOException, InterruptedException {

       super.initialize(context);

       delimiter = GIRAPH_TEXT_OUTPUT_FORMAT_SEPARATOR.get(getConf());

       reverseOutput = GIRAPH_TEXT_OUTPUT_FORMAT_REVERSE.get(getConf());

     }

     @Override

     protected Text convertEdgeToLine(I sourceId, V sourceValue, Edge<I, E> edge)

       throws IOException {

       StringBuilder msg = new StringBuilder();

       if (reverseOutput) {

         msg.append(edge.getValue().toString());

         msg.append(delimiter);

         msg.append(edge.getTargetVertexId().toString());

         msg.append(delimiter);

         msg.append(sourceId.toString());

       } else {

         msg.append(sourceId.toString());

         msg.append(delimiter);

         msg.append(edge.getTargetVertexId().toString());

         msg.append(delimiter);

         msg.append(edge.getValue().toString());

       }

       return new Text(msg.toString());

     }

   }

 }