/*
 * 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 org.apache.flink.api.common.operators.Order;
import org.apache.flink.api.common.operators.Ordering;
import org.apache.flink.api.common.operators.util.FieldSet;
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;

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

/**
 * The properties file belonging to the GroupCombineNode. It translates the GroupCombine operation
 * to the driver strategy SORTED_GROUP_COMBINE and sets the relevant grouping and sorting keys.
 * @see org.apache.flink.optimizer.dag.GroupCombineNode
 */
public final class GroupCombineProperties extends OperatorDescriptorSingle {

	private final Ordering ordering;        // ordering that we need to use if an additional ordering is requested 

	public GroupCombineProperties(FieldSet groupKeys, Ordering additionalOrderKeys) {
		super(groupKeys);

		// if we have an additional ordering, construct the ordering to have primarily the grouping fields
		
		this.ordering = new Ordering();
		for (Integer key : this.keyList) {
			this.ordering.appendOrdering(key, null, Order.ANY);
		}

		// and next the additional order fields
		if (additionalOrderKeys != null) {
			for (int i = 0; i < additionalOrderKeys.getNumberOfFields(); i++) {
				Integer field = additionalOrderKeys.getFieldNumber(i);
				Order order = additionalOrderKeys.getOrder(i);
				this.ordering.appendOrdering(field, additionalOrderKeys.getType(i), order);
			}
		}

	}

	@Override
	public DriverStrategy getStrategy() {
		return DriverStrategy.SORTED_GROUP_COMBINE;
	}

	@Override
	public SingleInputPlanNode instantiate(Channel in, SingleInputNode node) {
		node.setParallelism(in.getSource().getParallelism());
		
		// sorting key info
		SingleInputPlanNode singleInputPlanNode = new SingleInputPlanNode(
				node, 
				"GroupCombine (" + node.getOperator().getName() + ")",
				in, // reuse the combine strategy also used in the group reduce
				DriverStrategy.SORTED_GROUP_COMBINE, this.keyList);

		// set sorting comparator key info
		singleInputPlanNode.setDriverKeyInfo(this.ordering.getInvolvedIndexes(), this.ordering.getFieldSortDirections(), 0);
		// set grouping comparator key info
		singleInputPlanNode.setDriverKeyInfo(this.keyList, 1);
		
		return singleInputPlanNode;
	}

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

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

	@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();
	}
}