/*
    * 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.block_app.test_setup.graphs;
  
  import java.util.Random;
  
  import org.apache.giraph.block_app.test_setup.NumericTestGraph;
  import org.apache.giraph.block_app.test_setup.TestGraphModifier;
  import org.apache.giraph.conf.FloatConfOption;
  import org.apache.giraph.conf.GiraphConfiguration;
  import org.apache.giraph.conf.IntConfOption;
  import org.apache.giraph.function.Supplier;
  import org.apache.hadoop.io.Writable;
  import org.apache.hadoop.io.WritableComparable;
  
  /**
   * Creates synthetic graphs, that can have community structure.
   *
   * @param <I> Vertex id type
   * @param <V> Vertex value type
   * @param <E> Edge value type
   */
  public class SyntheticGraphInit<I extends WritableComparable,
      V extends Writable, E extends Writable>
      implements TestGraphModifier<I, V, E> {
    public static final IntConfOption NUM_COMMUNITIES = new IntConfOption(
        "test.SyntheticGraphCreator.NUM_COMMUNITIES", -1, "");
    public static final IntConfOption NUM_VERTICES = new IntConfOption(
        "test.SyntheticGraphCreator.NUM_VERTICES", -1, "");
    public static final IntConfOption NUM_EDGES_PER_VERTEX = new IntConfOption(
        "test.SyntheticGraphCreator.NUM_EDGES_PER_VERTEX", -1, "");
    public static final FloatConfOption ACTUAL_LOCALITY_RATIO =
        new FloatConfOption(
              "test.SyntheticGraphCreator.ACTUAL_LOCALITY_RATIO", -1, "");
  
    protected final Supplier<E> edgeSupplier;
  
    public SyntheticGraphInit(Supplier<E> edgeSupplier) {
      this.edgeSupplier = edgeSupplier;
    }
  
    public SyntheticGraphInit() {
      this.edgeSupplier = null;
    }
  
    @Override
    public void modifyGraph(NumericTestGraph<I, V, E> graph) {
      GiraphConfiguration conf = graph.getConf();
      int numPartitions = NUM_COMMUNITIES.get(conf);
      int numVertices = NUM_VERTICES.get(conf);
      int numEdgesPerVertex = NUM_EDGES_PER_VERTEX.get(conf);
      int communitySize = numVertices / numPartitions;
      float actualLocalityRatio = ACTUAL_LOCALITY_RATIO.get(conf);
      Random random = new Random(42);
      for (int i = 0; i < numVertices; ++i) {
        for (int e = 0; e < numEdgesPerVertex / 2; ++e) {
          boolean localEdge = random.nextFloat() < actualLocalityRatio;
          int community = i / communitySize;
          int j;
          do {
            if (localEdge) {
              j = community * communitySize + random.nextInt(communitySize);
            } else {
              j = random.nextInt(numVertices);
            }
          } while (j == i);
          graph.addSymmetricEdge(
              i, j, edgeSupplier != null ? edgeSupplier.get() : null);
        }
      }
    }
  }