// 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.

// This file is copied from

// https://github.com/ClickHouse/ClickHouse/blob/master/src/AggregateFunctions/AggregateFunctionDistinct.cpp

// and modified by Doris

#include "exprs/aggregate/aggregate_function_distinct.h"

#include <algorithm>

#include "core/data_type/data_type_nullable.h"

#include "exprs/aggregate/aggregate_function_combinator.h"

#include "exprs/aggregate/aggregate_function_simple_factory.h"

#include "exprs/aggregate/helpers.h"

namespace doris {

template <PrimitiveType T>

struct Reducer {

    template <bool stable>

    using Output = AggregateFunctionDistinctSingleNumericData<T, stable>;

    using AggregateFunctionDistinctNormal = AggregateFunctionDistinct<Output, false>;

};

template <PrimitiveType T>

using AggregateFunctionDistinctNumeric = typename Reducer<T>::AggregateFunctionDistinctNormal;

class AggregateFunctionCombinatorDistinct final : public IAggregateFunctionCombinator {

public:

    String get_name() const override { return "Distinct"; }

    DataTypes transform_arguments(const DataTypes& arguments) const override {

        if (arguments.empty()) {

            throw doris::Exception(

                    ErrorCode::INTERNAL_ERROR,

                    "Incorrect number of arguments for aggregate function with Distinct suffix");

        }

        return arguments;

    }

    AggregateFunctionPtr transform_aggregate_function(

            const AggregateFunctionPtr& nested_function, const DataTypes& arguments,

            const bool result_is_nullable, const AggregateFunctionAttr& attr) const override {

        DCHECK(nested_function != nullptr);

        if (nested_function == nullptr) {

            return nullptr;

        }

        if (arguments.size() == 1) {

            AggregateFunctionPtr res(

                    creator_with_type_list<TYPE_TINYINT, TYPE_SMALLINT, TYPE_INT, TYPE_BIGINT,

                                           TYPE_LARGEINT>::

                            create<AggregateFunctionDistinctNumeric>(arguments, result_is_nullable,

                                                                     attr, nested_function));

            if (res) {

                return res;

            }

            res = creator_without_type::create<

                    AggregateFunctionDistinct<AggregateFunctionDistinctSingleGenericData>>(

                    arguments, result_is_nullable, attr, nested_function);

            return res;

        }

        return creator_without_type::create<

                AggregateFunctionDistinct<AggregateFunctionDistinctMultipleGenericData>>(

                arguments, result_is_nullable, attr, nested_function);

    }

};

void register_aggregate_function_combinator_distinct(AggregateFunctionSimpleFactory& factory) {

    AggregateFunctionCreator creator = [&](const std::string& name, const DataTypes& types,

                                           const DataTypePtr& result_type,

                                           const bool result_is_nullable,

                                           const AggregateFunctionAttr& attr) {

        // 1. we should get not nullable types;

        DataTypes nested_types(types.size());

        std::ranges::transform(types, nested_types.begin(),

                               [](const auto& e) { return remove_nullable(e); });

        auto function_combinator = std::make_shared<AggregateFunctionCombinatorDistinct>();

        auto transform_arguments = function_combinator->transform_arguments(nested_types);

        auto nested_function_name = name.substr(DISTINCT_FUNCTION_PREFIX.size());

        auto nested_function = factory.get(nested_function_name, transform_arguments, result_type,

                                           false, BeExecVersionManager::get_newest_version(), attr);

        return function_combinator->transform_aggregate_function(nested_function, types,

                                                                 result_is_nullable, attr);

    };

    factory.register_distinct_function_combinator(creator, DISTINCT_FUNCTION_PREFIX);

    factory.register_distinct_function_combinator(creator, DISTINCT_FUNCTION_PREFIX, true);

}

} // namespace doris