/*
 * 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.flink.optimizer.operators;

import java.util.Collections;
import java.util.List;

import org.apache.flink.api.common.operators.base.GroupReduceOperatorBase;
import org.apache.flink.api.common.operators.util.FieldSet;
import org.apache.flink.optimizer.dag.GroupReduceNode;
import org.apache.flink.optimizer.dag.SingleInputNode;
import org.apache.flink.optimizer.dataproperties.GlobalProperties;
import org.apache.flink.optimizer.dataproperties.LocalProperties;
import org.apache.flink.optimizer.dataproperties.PartitioningProperty;
import org.apache.flink.optimizer.dataproperties.RequestedGlobalProperties;
import org.apache.flink.optimizer.dataproperties.RequestedLocalProperties;
import org.apache.flink.optimizer.plan.Channel;
import org.apache.flink.optimizer.plan.SingleInputPlanNode;
import org.apache.flink.runtime.operators.DriverStrategy;

public final class PartialGroupProperties extends OperatorDescriptorSingle {
	
	public PartialGroupProperties(FieldSet keys) {
		super(keys);
	}
	
	@Override
	public DriverStrategy getStrategy() {
		return DriverStrategy.SORTED_GROUP_COMBINE;
	}

	@Override
	public SingleInputPlanNode instantiate(Channel in, SingleInputNode node) {
		// create in input node for combine with the same parallelism as input node
		GroupReduceNode combinerNode = new GroupReduceNode((GroupReduceOperatorBase<?, ?, ?>) node.getOperator());
		combinerNode.setParallelism(in.getSource().getParallelism());

		SingleInputPlanNode combiner = new SingleInputPlanNode(combinerNode, "Combine("+node.getOperator().getName()+")", in,
				DriverStrategy.SORTED_GROUP_COMBINE);
		// sorting key info
		combiner.setDriverKeyInfo(in.getLocalStrategyKeys(), in.getLocalStrategySortOrder(), 0);
		// set grouping comparator key info
		combiner.setDriverKeyInfo(this.keyList, 1);
		
		return combiner;
	}

	@Override
	protected List<RequestedGlobalProperties> createPossibleGlobalProperties() {
		return Collections.singletonList(new RequestedGlobalProperties());
	}

	@Override
	protected List<RequestedLocalProperties> createPossibleLocalProperties() {
		RequestedLocalProperties props = new RequestedLocalProperties();
		props.setGroupedFields(this.keys);
		return Collections.singletonList(props);
	}
	
	@Override
	public GlobalProperties computeGlobalProperties(GlobalProperties gProps) {
		if (gProps.getUniqueFieldCombination() != null && gProps.getUniqueFieldCombination().size() > 0 &&
				gProps.getPartitioning() == PartitioningProperty.RANDOM_PARTITIONED)
		{
			gProps.setAnyPartitioning(gProps.getUniqueFieldCombination().iterator().next().toFieldList());
		}
		gProps.clearUniqueFieldCombinations();
		return gProps;
	}
	
	@Override
	public LocalProperties computeLocalProperties(LocalProperties lProps) {
		return lProps.clearUniqueFieldSets();
	}
}