/*
 * Copyright 2009-2010 by The Regents of the University of California
 * Licensed 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 from
 * 
 *     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 edu.uci.ics.hyracks.dataflow.std.aggregators;

import java.io.DataOutput;
import java.io.IOException;

import edu.uci.ics.hyracks.api.comm.IFrameTupleAccessor;
import edu.uci.ics.hyracks.api.exceptions.HyracksDataException;
import edu.uci.ics.hyracks.dataflow.common.data.marshalling.IntegerSerializerDeserializer;

/**
 * SUM aggregator factory (for integer only; another SUM aggregator for floats
 * is available at {@link FloatSumAggregatorFactory})
 * 
 */
public class SumAggregatorFactory implements
		IFieldValueResultingAggregatorFactory {

	private int sumField;

	public SumAggregatorFactory(int field) {
		sumField = field;
	}

	/**
	 * 
	 */
	private static final long serialVersionUID = 1L;

	/*
	 * (non-Javadoc)
	 * 
	 * @see edu.uci.ics.hyracks.dataflow.std.aggregators.
	 * IFieldValueResultingAggregatorFactory
	 * #createFieldValueResultingAggregator()
	 */
	@Override
	public IFieldValueResultingAggregator createFieldValueResultingAggregator() {
		return new IFieldValueResultingAggregator() {
			private int sum;

			@Override
			public void output(DataOutput resultAcceptor)
					throws HyracksDataException {
				try {
					resultAcceptor.writeInt(sum);
				} catch (IOException e) {
					throw new HyracksDataException(e);
				}
			}

			@Override
			public void init(IFrameTupleAccessor accessor, int tIndex)
					throws HyracksDataException {
				sum++;
			}

			@Override
			public void accumulate(IFrameTupleAccessor accessor, int tIndex)
					throws HyracksDataException {
				int tupleOffset = accessor.getTupleStartOffset(tIndex);
				int fieldCount = accessor.getFieldCount();
				int fieldStart = accessor.getFieldStartOffset(tIndex, sumField);
				sum += IntegerSerializerDeserializer.getInt(accessor
						.getBuffer().array(), tupleOffset + 2 * fieldCount
						+ fieldStart);
			}
		};
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see edu.uci.ics.hyracks.dataflow.std.aggregators.spillable.
	 * ISpillableFieldValueResultingAggregatorFactory
	 * #createFieldValueResultingAggregator()
	 */
	@Override
	public ISpillableFieldValueResultingAggregator createSpillableFieldValueResultingAggregator() {
		return new ISpillableFieldValueResultingAggregator() {

			private int sum;

			@Override
			public void output(DataOutput resultAcceptor)
					throws HyracksDataException {
				try {
					resultAcceptor.writeInt(sum);
				} catch (IOException ex) {
					throw new HyracksDataException(ex);
				}
			}

			@Override
			public void initFromPartial(IFrameTupleAccessor accessor,
					int tIndex, int fIndex) throws HyracksDataException {
				sum = IntegerSerializerDeserializer.getInt(
						accessor.getBuffer().array(),
						accessor.getTupleStartOffset(tIndex)
								+ accessor.getFieldCount() * 2
								+ accessor.getFieldStartOffset(tIndex, fIndex));
			}

			@Override
			public void init(IFrameTupleAccessor accessor, int tIndex)
					throws HyracksDataException {
				sum = 0;
			}

			@Override
			public void accumulatePartialResult(IFrameTupleAccessor accessor,
					int tIndex, int fIndex) throws HyracksDataException {
				sum += IntegerSerializerDeserializer.getInt(
						accessor.getBuffer().array(),
						accessor.getTupleStartOffset(tIndex)
								+ accessor.getFieldCount() * 2
								+ accessor.getFieldStartOffset(tIndex, fIndex));
			}

			@Override
			public void accumulate(IFrameTupleAccessor accessor, int tIndex)
					throws HyracksDataException {
				int tupleOffset = accessor.getTupleStartOffset(tIndex);
				int fieldCount = accessor.getFieldCount();
				int fieldStart = accessor.getFieldStartOffset(tIndex, sumField);
				sum += IntegerSerializerDeserializer.getInt(accessor
						.getBuffer().array(), tupleOffset + 2 * fieldCount
						+ fieldStart);
			}
		};
	}

}