/*

  * 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.edge;

 import com.google.common.collect.Lists;

 import org.apache.giraph.utils.Trimmable;

 import org.apache.giraph.utils.WritableUtils;

 import org.apache.hadoop.io.Writable;

 import org.apache.hadoop.io.WritableComparable;

 import java.io.DataInput;

 import java.io.DataOutput;

 import java.io.IOException;

 import java.util.ArrayList;

 import java.util.Iterator;

 /**

  * {@link OutEdges} implementation backed by an {@link ArrayList}.

  * Parallel edges are allowed.

  *

  * @param <I> Vertex id

  * @param <E> Edge value

  */

 public class ArrayListEdges<I extends WritableComparable, E extends Writable>

     extends ConfigurableOutEdges<I, E>

     implements MutableOutEdges<I, E>, Trimmable {

   /** List of edges. */

   private ArrayList<Edge<I, E>> edgeList;

   @Override

   public void initialize(Iterable<Edge<I, E>> edges) {

     // If the iterable is actually an instance of ArrayList,

     // we simply copy the reference.

     // Otherwise we have to add every edge.

     if (edges instanceof ArrayList) {

       edgeList = (ArrayList<Edge<I, E>>) edges;

     } else {

       edgeList = Lists.newArrayList(edges);

     }

   }

   @Override

   public void initialize(int capacity) {

     edgeList = Lists.newArrayListWithCapacity(capacity);

   }

   @Override

   public void initialize() {

     edgeList = Lists.newArrayList();

   }

   @Override

   public void add(Edge<I, E> edge) {

     edgeList.add(edge);

   }

   @Override

   public void remove(I targetVertexId) {

     for (Iterator<Edge<I, E>> edges = edgeList.iterator(); edges.hasNext();) {

       Edge<I, E> edge = edges.next();

       if (edge.getTargetVertexId().equals(targetVertexId)) {

         edges.remove();

       }

     }

   }

   @Override

   public int size() {

     return edgeList.size();

   }

   @Override

   public final Iterator<Edge<I, E>> iterator() {

     return edgeList.iterator();

   }

   @Override

   @SuppressWarnings("unchecked")

   public Iterator<MutableEdge<I, E>> mutableIterator() {

     // The downcast is fine because all concrete Edge implementations are

     // mutable, but we only expose the mutation functionality when appropriate.

     return (Iterator) iterator();

   }

   @Override

   public void write(DataOutput out) throws IOException {

     out.writeInt(edgeList.size());

     for (Edge<I, E> edge : edgeList) {

       edge.getTargetVertexId().write(out);

       edge.getValue().write(out);

     }

   }

   @Override

   public void readFields(DataInput in) throws IOException {

     int numEdges = in.readInt();

     initialize(numEdges);

     for (int i = 0; i < numEdges; ++i) {

       Edge<I, E> edge = getConf().createEdge();

       WritableUtils.readEdge(in, edge);

       edgeList.add(edge);

     }

   }

   @Override

   public void trim() {

     edgeList.trimToSize();

   }

 }