/*
    * 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 org.apache.giraph.graph.Vertex;
  import org.apache.giraph.io.VertexInputFormat;
  import org.apache.giraph.io.VertexReader;
  import org.apache.hadoop.conf.Configuration;
  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.hadoop.mapreduce.lib.input.SequenceFileInputFormat;
  
  import java.io.IOException;
  import java.util.List;
  
  /**
   * Sequence file vertex input format based on {@link SequenceFileInputFormat}.
   *
   * @param <I> Vertex id
   * @param <V> Vertex data
   * @param <E> Edge data
   * @param <X> Value type
   */
  @SuppressWarnings("rawtypes")
  public class SequenceFileVertexInputFormat<I extends WritableComparable,
      V extends Writable, E extends Writable, X extends Vertex<I, V, E>>
      extends VertexInputFormat<I, V, E> {
    /** Internal input format */
    protected SequenceFileInputFormat<I, X> sequenceFileInputFormat =
      new SequenceFileInputFormat<I, X>();
  
    @Override public void checkInputSpecs(Configuration conf) { }
  
    @Override
    public List<InputSplit> getSplits(JobContext context, int minSplitCountHint)
      throws IOException, InterruptedException {
      return sequenceFileInputFormat.getSplits(context);
    }
  
    @Override
    public VertexReader<I, V, E> createVertexReader(InputSplit split,
        TaskAttemptContext context) throws IOException {
      return new SequenceFileVertexReader<I, V, E, X>(
          sequenceFileInputFormat.createRecordReader(split, context));
    }
  
    /**
     * Vertex reader used with {@link SequenceFileVertexInputFormat}.
     *
     * @param <I> Vertex id
     * @param <V> Vertex data
     * @param <E> Edge data
     * @param <X> Value type
     */
    public static class SequenceFileVertexReader<I extends WritableComparable,
        V extends Writable, E extends Writable, X extends Vertex<I, V, E>>
        extends VertexReader<I, V, E> {
      /** Internal record reader from {@link SequenceFileInputFormat} */
      private final RecordReader<I, X> recordReader;
  
      /**
       * Constructor with record reader.
       *
       * @param recordReader Reader from {@link SequenceFileInputFormat}.
       */
      public SequenceFileVertexReader(RecordReader<I, X> recordReader) {
        this.recordReader = recordReader;
      }
  
      @Override public void initialize(InputSplit inputSplit,
          TaskAttemptContext context) throws IOException, InterruptedException {
        recordReader.initialize(inputSplit, context);
      }
  
      @Override public boolean nextVertex() throws IOException,
          InterruptedException {
        return recordReader.nextKeyValue();
      }
  
      @Override public Vertex<I, V, E> getCurrentVertex()
       throws IOException, InterruptedException {
       return recordReader.getCurrentValue();
     }
 
 
     @Override public void close() throws IOException {
       recordReader.close();
     }
 
     @Override public float getProgress() throws IOException,
         InterruptedException {
       return recordReader.getProgress();
     }
   }
 }