/*

  * 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 static org.apache.giraph.conf.GiraphConstants.EDGE_OUTPUT_FORMAT_SUBDIR;

 import java.io.IOException;

 import org.apache.giraph.edge.Edge;

 import org.apache.giraph.io.EdgeOutputFormat;

 import org.apache.giraph.io.EdgeWriter;

 import org.apache.hadoop.io.Text;

 import org.apache.hadoop.io.Writable;

 import org.apache.hadoop.io.WritableComparable;

 import org.apache.hadoop.mapreduce.JobContext;

 import org.apache.hadoop.mapreduce.OutputCommitter;

 import org.apache.hadoop.mapreduce.RecordWriter;

 import org.apache.hadoop.mapreduce.TaskAttemptContext;

 /**

  * Abstract class that users should subclass to use their own text based

  * edge output format.

  *

  * @param <I> Vertex index value

  * @param <V> Vertex value

  * @param <E> Edge value

  */

 @SuppressWarnings("rawtypes")

 public abstract class TextEdgeOutputFormat<I extends WritableComparable,

     V extends Writable, E extends Writable>

     extends EdgeOutputFormat<I, V, E> {

   /** Uses the TextOutputFormat to do everything */

   protected GiraphTextOutputFormat textOutputFormat =

     new GiraphTextOutputFormat() {

       @Override

       protected String getSubdir() {

         return EDGE_OUTPUT_FORMAT_SUBDIR.get(getConf());

       }

     };

   @Override

   public void checkOutputSpecs(JobContext context)

     throws IOException, InterruptedException {

     textOutputFormat.checkOutputSpecs(context);

   }

   @Override

   public OutputCommitter getOutputCommitter(TaskAttemptContext context)

     throws IOException, InterruptedException {

     return textOutputFormat.getOutputCommitter(context);

   }

   /**

    * The factory method which produces the {@link TextEdgeWriter} used by this

    * output format.

    *

    * @param context  the information about the task

    * @return         the text edge writer to be used

    */

   @Override

   public abstract TextEdgeWriter createEdgeWriter(TaskAttemptContext

       context) throws IOException, InterruptedException;

   /**

    * Abstract class to be implemented by the user based on their specific

    * edge output.  Easiest to ignore the key value separator and only use

    * key instead.

    */

   protected abstract class TextEdgeWriter<I extends WritableComparable,

     V extends Writable, E extends Writable>

       extends EdgeWriter<I, V, E> {

     /** Internal line record writer */

     private RecordWriter<Text, Text> lineRecordWriter;

     /** Context passed to initialize */

     private TaskAttemptContext context;

     @Override

     public void initialize(TaskAttemptContext context) throws IOException,

            InterruptedException {

       lineRecordWriter = createLineRecordWriter(context);

       this.context = context;

     }

     /**

      * Create the line record writer. Override this to use a different

      * underlying record writer (useful for testing).

      *

      * @param  context the context passed to initialize

      * @return the record writer to be used

      * @throws IOException          exception that can be thrown during creation

      * @throws InterruptedException exception that can be thrown during creation

      */

     protected RecordWriter<Text, Text> createLineRecordWriter(

         TaskAttemptContext context) throws IOException, InterruptedException {

       return textOutputFormat.getRecordWriter(context);

     }

     @Override

     public void close(TaskAttemptContext context) throws IOException,

         InterruptedException {

       lineRecordWriter.close(context);

     }

     /**

      * Get the line record writer.

      *

      * @return Record writer to be used for writing.

      */

     public RecordWriter<Text, Text> getRecordWriter() {

       return lineRecordWriter;

     }

     /**

      * Get the context.

      *

      * @return Context passed to initialize.

      */

     public TaskAttemptContext getContext() {

       return context;

     }

   }

   /**

    * Abstract class to be implemented by the user to write a line for each

    * edge.

    */

   protected abstract class TextEdgeWriterToEachLine<

     I extends WritableComparable, V extends Writable, E extends Writable>

     extends TextEdgeWriter<I, V, E> {

     @Override

     public final void writeEdge(I sourceId, V sourceValue, Edge<I, E> edge)

       throws IOException, InterruptedException {

       // Note we are writing line as key with null value

       getRecordWriter().write(

         convertEdgeToLine(sourceId, sourceValue, edge), null);

     }

     /**

      * Writes a line for the given edge.

      *

      * @param sourceId    the current id of the source vertex

      * @param sourceValue the current value of the source vertex

      * @param edge        the current vertex for writing

      * @return the text line to be written

      * @throws IOException exception that can be thrown while writing

      */

     protected abstract Text convertEdgeToLine(I sourceId,

       V sourceValue, Edge<I, E> edge) throws IOException;

   }

 }