/*
 * 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 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 io.prestosql.operator.aggregation;

import com.google.common.collect.ImmutableList;
import io.prestosql.spi.block.Block;
import io.prestosql.spi.block.BlockBuilder;
import io.prestosql.spi.type.StandardTypes;

import java.util.List;

import static io.prestosql.spi.type.RealType.REAL;
import static java.lang.Float.floatToRawIntBits;

public class TestRealGeometricMeanAggregation
        extends AbstractTestAggregationFunction
{
    @Override
    protected Block[] getSequenceBlocks(int start, int length)
    {
        BlockBuilder blockBuilder = REAL.createBlockBuilder(null, length);
        for (int i = start; i < start + length; i++) {
            REAL.writeLong(blockBuilder, floatToRawIntBits((float) i));
        }
        return new Block[] {blockBuilder.build()};
    }

    @Override
    protected Number getExpectedValue(int start, int length)
    {
        if (length == 0) {
            return null;
        }

        double product = 1.0d;
        for (int i = start; i < start + length; i++) {
            product *= i;
        }
        return (float) Math.pow(product, 1.0d / length);
    }

    @Override
    protected String getFunctionName()
    {
        return "geometric_mean";
    }

    @Override
    protected List<String> getFunctionParameterTypes()
    {
        return ImmutableList.of(StandardTypes.REAL);
    }
}
