/*

  * 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.examples.io.formats;

 import java.io.IOException;

 import java.util.List;

 import org.apache.giraph.edge.Edge;

 import org.apache.giraph.edge.EdgeFactory;

 import org.apache.giraph.examples.utils.BrachaTouegDeadlockVertexValue;

 import org.apache.giraph.graph.Vertex;

 import org.apache.giraph.io.formats.TextVertexInputFormat;

 import org.apache.hadoop.io.LongWritable;

 import org.apache.hadoop.io.Text;

 import org.apache.hadoop.mapreduce.InputSplit;

 import org.apache.hadoop.mapreduce.TaskAttemptContext;

 import org.json.JSONArray;

 import org.json.JSONException;

 import com.google.common.collect.Lists;

 /**

   * VertexInputFormat for the Bracha Toueg Deadlock Detection algorithm

   * specified in JSON format.

   */

 public class BrachaTouegDeadlockInputFormat extends

   TextVertexInputFormat<LongWritable, BrachaTouegDeadlockVertexValue,

     LongWritable> {

   @Override

   public TextVertexReader createVertexReader(InputSplit split,

       TaskAttemptContext context) {

     return new JsonLongLongLongLongVertexReader();

   }

  /**

   * VertexReader use for the Bracha Toueg Deadlock Detection Algorithm.

   * The files should be in the following JSON format:

   * JSONArray(<vertex id>,

   *   JSONArray(JSONArray(<dest vertex id>, <edge tag>), ...))

   * The tag is use for the N-out-of-M semantics. Two edges with the same tag

   * are considered to be combined and, hence, represent to combined requests

   * that need to be both satisfied to continue execution.

   * Here is an example with vertex id 1, and three edges (requests).

   * First edge has a destination vertex 2 with tag 0.

   * Second and third edge have a destination vertex respectively of 3 and 4

   * with tag 1.

   * [1,[[2,0], [3,1], [4,1]]]

   */

   class JsonLongLongLongLongVertexReader

     extends TextVertexReaderFromEachLineProcessedHandlingExceptions<JSONArray,

             JSONException> {

     @Override

     protected JSONArray preprocessLine(Text line) throws JSONException {

       return new JSONArray(line.toString());

     }

     @Override

     protected LongWritable getId(JSONArray jsonVertex) throws JSONException,

               IOException {

       return new LongWritable(jsonVertex.getLong(0));

     }

     @Override

     protected BrachaTouegDeadlockVertexValue getValue(JSONArray jsonVertex)

       throws JSONException, IOException {

       return new BrachaTouegDeadlockVertexValue();

     }

     @Override

     protected Iterable<Edge<LongWritable, LongWritable>>

     getEdges(JSONArray jsonVertex) throws JSONException, IOException {

       JSONArray jsonEdgeArray = jsonVertex.getJSONArray(1);

       /* get the edges */

       List<Edge<LongWritable, LongWritable>> edges =

           Lists.newArrayListWithCapacity(jsonEdgeArray.length());

       for (int i = 0; i < jsonEdgeArray.length(); ++i) {

         LongWritable targetId;

         LongWritable tag;

         JSONArray jsonEdge = jsonEdgeArray.getJSONArray(i);

         targetId = new LongWritable(jsonEdge.getLong(0));

         tag = new LongWritable((long) jsonEdge.getLong(1));

         edges.add(EdgeFactory.create(targetId, tag));

       }

       return edges;

     }

     @Override

     protected Vertex<LongWritable, BrachaTouegDeadlockVertexValue,

       LongWritable> handleException(Text line, JSONArray jsonVertex,

           JSONException e) {

       throw new IllegalArgumentException(

           "Couldn't get vertex from line " + line, e);

     }

   }

 }