/*
    * 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.iterables;
  
  import org.apache.giraph.conf.ImmutableClassesGiraphConfiguration;
  import org.apache.giraph.graph.Vertex;
  import org.apache.giraph.io.VertexReader;
  import org.apache.hadoop.io.Writable;
  import org.apache.hadoop.io.WritableComparable;
  import org.apache.hadoop.mapreduce.InputSplit;
  import org.apache.hadoop.mapreduce.TaskAttemptContext;
  
  import java.io.IOException;
  
  /**
   * Wraps {@link GiraphReader} for vertices into {@link VertexReader}
   *
   * @param <I> Vertex id
   * @param <V> Vertex data
   * @param <E> Edge data
   */
  public class VertexReaderWrapper<I extends WritableComparable,
      V extends Writable, E extends Writable> extends VertexReader<I, V, E> {
    /** Wrapped vertex reader */
    private GiraphReader<Vertex<I, V, E>> vertexReader;
    /** {@link VertexReader}-like wrapper of {@link #vertexReader} */
    private IteratorToReaderWrapper<Vertex<I, V, E>> iterator;
  
    /**
     * Constructor
     *
     * @param vertexReader GiraphReader for vertices to wrap
     */
    public VertexReaderWrapper(GiraphReader<Vertex<I, V, E>> vertexReader) {
      this.vertexReader = vertexReader;
      iterator = new IteratorToReaderWrapper<Vertex<I, V, E>>(vertexReader);
    }
  
    @Override
    public void setConf(
        ImmutableClassesGiraphConfiguration<I, V, E> conf) {
      super.setConf(conf);
      conf.configureIfPossible(vertexReader);
    }
  
    @Override
    public boolean nextVertex() throws IOException, InterruptedException {
      return iterator.nextObject();
    }
  
    @Override
    public Vertex<I, V, E> getCurrentVertex() throws IOException,
        InterruptedException {
      return iterator.getCurrentObject();
    }
  
    @Override
    public void initialize(InputSplit inputSplit,
        TaskAttemptContext context) throws IOException, InterruptedException {
      vertexReader.initialize(inputSplit, context);
    }
  
    @Override
    public void close() throws IOException {
      vertexReader.close();
    }
  
    @Override
    public float getProgress() throws IOException, InterruptedException {
      return vertexReader.getProgress();
    }
  }