// 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/Combinators/AggregateFunctionForEach.cpp

// and modified by Doris

#include <memory>

#include "common/logging.h"

#include "core/data_type/data_type_array.h"

#include "core/data_type/data_type_nullable.h"

#include "exprs/aggregate/aggregate_function.h"

#include "exprs/aggregate/aggregate_function_foreach.h"

#include "exprs/aggregate/aggregate_function_simple_factory.h"

#include "exprs/aggregate/helpers.h"

namespace doris {

// The difference between AggregateFunctionForEachV2 and AggregateFunctionForEach is that its return value array is always an Array<Nullable<T>>.

// For example, AggregateFunctionForEach's count_foreach([1,2,3]) returns Array<Int64>, which is not ideal

// because we may have already assumed that the array's elements are always nullable types, and many places have such checks.

// V1 code is kept to ensure compatibility during upgrades and downgrades.

// V2 code differs from V1 only in the return type and insert_into logic; all other logic is exactly the same.

class AggregateFunctionForEachV2 : public AggregateFunctionForEach {

public:

    constexpr static auto AGG_FOREACH_SUFFIX = "_foreachv2";

    AggregateFunctionForEachV2(AggregateFunctionPtr nested_function_, const DataTypes& arguments)

            : AggregateFunctionForEach(nested_function_, arguments) {}

    DataTypePtr get_return_type() const override {

        return std::make_shared<DataTypeArray>(make_nullable(nested_function->get_return_type()));

    }

    void insert_result_into(ConstAggregateDataPtr __restrict place, IColumn& to) const override {

        const AggregateFunctionForEachData& state = data(place);

        auto& arr_to = assert_cast<ColumnArray&>(to);

        auto& offsets_to = arr_to.get_offsets();

        IColumn& elems_nullable = arr_to.get_data();

        DCHECK(elems_nullable.is_nullable());

        auto& elems_to = assert_cast<ColumnNullable&>(elems_nullable).get_nested_column();

        auto& elements_null_map =

                assert_cast<ColumnNullable&>(elems_nullable).get_null_map_column();

        if (nested_function->get_return_type()->is_nullable()) {

            char* nested_state = state.array_of_aggregate_datas;

            for (size_t i = 0; i < state.dynamic_array_size; ++i) {

                nested_function->insert_result_into(nested_state, elems_nullable);

                nested_state += nested_size_of_data;

            }

        } else {

            char* nested_state = state.array_of_aggregate_datas;

            for (size_t i = 0; i < state.dynamic_array_size; ++i) {

                nested_function->insert_result_into(nested_state, elems_to);

                elements_null_map.insert_default(); // not null

                nested_state += nested_size_of_data;

            }

        }

        offsets_to.push_back(offsets_to.back() + state.dynamic_array_size);

    }

};

void register_aggregate_function_combinator_foreachv2(AggregateFunctionSimpleFactory& factory) {

    AggregateFunctionCreator creator =

            [&](const std::string& name, const DataTypes& types, const DataTypePtr& result_type,

                const bool result_is_nullable,

                const AggregateFunctionAttr& attr) -> AggregateFunctionPtr {

        const std::string& suffix = AggregateFunctionForEachV2::AGG_FOREACH_SUFFIX;

        DataTypes transform_arguments;

        for (const auto& t : types) {

            auto item_type =

                    assert_cast<const DataTypeArray*>(remove_nullable(t).get())->get_nested_type();

            transform_arguments.push_back(item_type);

        }

        auto result_item_type =

                assert_cast<const DataTypeArray*>(remove_nullable(result_type).get())

                        ->get_nested_type();

        auto nested_function_name = name.substr(0, name.size() - suffix.size());

        auto nested_function =

                factory.get(nested_function_name, transform_arguments, result_item_type, true,

                            BeExecVersionManager::get_newest_version(), attr);

        if (!nested_function) {

            throw Exception(

                    ErrorCode::INTERNAL_ERROR,

                    "The combiner did not find a foreach combiner function. nested function "

                    "name {} , args {}",

                    nested_function_name, types_name(types));

        }

        return creator_without_type::create<AggregateFunctionForEachV2>(types, result_is_nullable,

                                                                        attr, nested_function);

    };

    factory.register_foreach_function_combinator(

            creator, AggregateFunctionForEachV2::AGG_FOREACH_SUFFIX, true);

    factory.register_foreach_function_combinator(

            creator, AggregateFunctionForEachV2::AGG_FOREACH_SUFFIX, false);

}

} // namespace doris