/*
 * 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 com.facebook.presto.operator.aggregation.arrayagg;

import com.facebook.presto.common.block.Block;
import com.facebook.presto.common.block.BlockBuilder;
import com.facebook.presto.common.type.ArrayType;
import com.facebook.presto.common.type.Type;
import com.facebook.presto.operator.aggregation.SetOfValues;
import com.facebook.presto.operator.aggregation.state.SetAggregationState;
import com.facebook.presto.spi.function.AccumulatorStateSerializer;

import java.lang.invoke.MethodHandle;

import static java.util.Objects.requireNonNull;

public class SetAggregationStateSerializer
        implements AccumulatorStateSerializer<SetAggregationState>
{
    private final ArrayType arrayType;
    private final MethodHandle elementIsDistinctFrom;

    public SetAggregationStateSerializer(Type elementType, MethodHandle elementIsDistinctFrom)
    {
        this.arrayType = new ArrayType(requireNonNull(elementType, "elementType is null"));
        this.elementIsDistinctFrom = requireNonNull(elementIsDistinctFrom, "element is distinct from is null");
    }

    @Override
    public Type getSerializedType()
    {
        return arrayType;
    }

    @Override
    public void serialize(SetAggregationState state, BlockBuilder out)
    {
        if (state.get() == null) {
            out.appendNull();
        }
        else {
            state.get().serialize(out);
        }
    }

    @Override
    public void deserialize(Block block, int index, SetAggregationState state)
    {
        state.set(new SetOfValues(arrayType.getObject(block, index), state.getElementType(), elementIsDistinctFrom));
    }
}
