/*
    * 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.reducers.collect;
  
  import java.io.DataInput;
  import java.io.DataOutput;
  import java.io.IOException;
  import java.util.ArrayList;
  import java.util.List;
  
  import org.apache.giraph.reducers.impl.KryoWrappedReduceOperation;
  import org.apache.giraph.types.ops.PrimitiveTypeOps;
  import org.apache.giraph.types.ops.TypeOpsUtils;
  import org.apache.giraph.types.ops.collections.ResettableIterator;
  import org.apache.giraph.types.ops.collections.array.WArrayList;
  import org.apache.giraph.utils.WritableUtils;
  
  /**
   * Collect tuples of primitive values reduce operation
   */
  public class CollectTuplesOfPrimitivesReduceOperation
      extends KryoWrappedReduceOperation<List<Object>, List<WArrayList>> {
    /**
     * Type ops if available, or null
     */
    private List<PrimitiveTypeOps> typeOpsList;
  
    /** For reflection only */
    public CollectTuplesOfPrimitivesReduceOperation() {
    }
  
    public CollectTuplesOfPrimitivesReduceOperation(
        List<PrimitiveTypeOps> typeOpsList) {
      this.typeOpsList = typeOpsList;
    }
  
    @Override
    public List<WArrayList> createValue() {
      List<WArrayList> ret = new ArrayList<>(typeOpsList.size());
      for (PrimitiveTypeOps typeOps : typeOpsList) {
        ret.add(typeOps.createArrayList());
      }
      return ret;
    }
  
    @Override
    public void reduce(List<WArrayList> reduceInto, List<Object> value) {
      for (int i = 0; i < reduceInto.size(); i++) {
        reduceInto.get(i).addW(value.get(i));
      }
    }
  
    @Override
    public void reduceMerge(final List<WArrayList> reduceInto,
        List<WArrayList> toReduce) {
      for (int i = 0; i < reduceInto.size(); i++) {
        ResettableIterator iterator = toReduce.get(i).fastIteratorW();
        while (iterator.hasNext()) {
          reduceInto.get(i).addW(iterator.next());
        }
      }
    }
  
    @Override
    public void write(DataOutput out) throws IOException {
      out.writeInt(typeOpsList.size());
      for (PrimitiveTypeOps typeOps : typeOpsList) {
        WritableUtils.writeClass(typeOps.getTypeClass(), out);
      }
    }
  
    @Override
    public void readFields(DataInput in) throws IOException {
      int size = in.readInt();
      typeOpsList = new ArrayList<>(size);
      for (int i = 0; i < size; i++) {
        typeOpsList.add(TypeOpsUtils.getPrimitiveTypeOps(
            WritableUtils.readClass(in)));
      }
    }
  }