/*
    * 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.accumulo.edgemarker;
  
  import org.apache.accumulo.core.data.Key;
  import org.apache.accumulo.core.data.Value;
  import org.apache.giraph.edge.Edge;
  import org.apache.giraph.edge.EdgeFactory;
  import org.apache.giraph.graph.Vertex;
  import org.apache.giraph.io.VertexReader;
  import org.apache.giraph.io.accumulo.AccumuloVertexInputFormat;
  import org.apache.hadoop.conf.Configuration;
  import org.apache.hadoop.io.Text;
  import org.apache.hadoop.mapreduce.InputSplit;
  import org.apache.hadoop.mapreduce.RecordReader;
  import org.apache.hadoop.mapreduce.TaskAttemptContext;
  
  import com.google.common.collect.Lists;
  
  import java.io.IOException;
  import java.util.List;
  import java.util.regex.Pattern;
  
  /*
   Example subclass which reads in Key/Value pairs to construct vertex objects.
   */
  public class AccumuloEdgeInputFormat
      extends AccumuloVertexInputFormat<Text, Text, Text> {
    @Override public void checkInputSpecs(Configuration conf) { }
  
    private static final Text uselessEdgeValue = new Text();
    public VertexReader<Text, Text, Text>
    createVertexReader(InputSplit split, TaskAttemptContext context)
        throws IOException {
      try {
  
        return new AccumuloEdgeVertexReader(
            accumuloInputFormat.createRecordReader(split, context)) {
        };
      } catch (InterruptedException e) {
        throw new IOException(e);
      }
  
    }
    /*
        Reader takes Key/Value pairs from the underlying input format.
     */
    public static class AccumuloEdgeVertexReader
        extends AccumuloVertexReader<Text, Text, Text> {
  
      public static final Pattern commaPattern = Pattern.compile("[,]");
  
      public AccumuloEdgeVertexReader(RecordReader<Key, Value> recordReader) {
        super(recordReader);
      }
  
  
      public boolean nextVertex() throws IOException, InterruptedException {
        return getRecordReader().nextKeyValue();
      }
  
      /*
     Each Key/Value contains the information needed to construct the vertices.
       */
      public Vertex<Text, Text, Text> getCurrentVertex()
          throws IOException, InterruptedException {
        Key key = getRecordReader().getCurrentKey();
        Value value = getRecordReader().getCurrentValue();
        Vertex<Text, Text, Text> vertex =
            getConfiguration().createVertex();
        Text vertexId = key.getRow();
        List<Edge<Text, Text>> edges = Lists.newLinkedList();
        String edge = new String(value.get());
        Text edgeId = new Text(edge);
        edges.add(EdgeFactory.create(edgeId, uselessEdgeValue));
        vertex.initialize(vertexId, new Text(), edges);
  
        return vertex;
      }
    }
  }