// Copyright 2023 PingCAP, Inc.
//
// 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.

#pragma once

#include <AggregateFunctions/IAggregateFunction.h>
#include <Columns/IColumn.h>
#include <DataTypes/DataTypeNothing.h>
#include <DataTypes/DataTypeNullable.h>


namespace DB
{
/** Aggregate function that takes arbitary number of arbitary arguments and does nothing.
  */
class AggregateFunctionNothing final : public IAggregateFunctionHelper<AggregateFunctionNothing>
{
public:
    String getName() const override { return "nothing"; }

    DataTypePtr getReturnType() const override
    {
        return std::make_shared<DataTypeNullable>(std::make_shared<DataTypeNothing>());
    }

    void create(AggregateDataPtr) const override {}

    void destroy(AggregateDataPtr) const noexcept override {}

    bool hasTrivialDestructor() const override { return true; }

    size_t sizeOfData() const override { return 0; }

    size_t alignOfData() const override { return 1; }

    void add(AggregateDataPtr, const IColumn **, size_t, Arena *) const override {}

    void merge(AggregateDataPtr, ConstAggregateDataPtr, Arena *) const override {}

    void serialize(ConstAggregateDataPtr, WriteBuffer &) const override {}

    void deserialize(AggregateDataPtr, ReadBuffer &, Arena *) const override {}

    void insertResultInto(ConstAggregateDataPtr, IColumn & to, Arena *) const override { to.insertDefault(); }

    const char * getHeaderFilePath() const override { return __FILE__; }
};

} // namespace DB