// 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.h

// and modified by Doris

#pragma once

#include "common/status.h"

#include "core/assert_cast.h"

#include "core/column/column_nullable.h"

#include "core/data_type/data_type_array.h"

#include "core/data_type/data_type_nullable.h"

#include "exec/common/arithmetic_overflow.h"

#include "exprs/aggregate/aggregate_function.h"

#include "exprs/function/array/function_array_utils.h"

namespace doris {

struct AggregateFunctionForEachData {

    size_t dynamic_array_size = 0;

    char* array_of_aggregate_datas = nullptr;

};

/** Adaptor for aggregate functions.

  * Adding -ForEach suffix to aggregate function

  *  will convert that aggregate function to a function, accepting arrays,

  *  and applies aggregation for each corresponding elements of arrays independently,

  *  returning arrays of aggregated values on corresponding positions.

  *

  * Example: sumForEach of:

  *  [1, 2],

  *  [3, 4, 5],

  *  [6, 7]

  * will return:

  *  [10, 13, 5]

  *

  * TODO Allow variable number of arguments.

  */

class AggregateFunctionForEach : public IAggregateFunctionDataHelper<AggregateFunctionForEachData,

                                                                     AggregateFunctionForEach>,

                                 VarargsExpression,

                                 NullableAggregateFunction {

protected:

    using Base =

            IAggregateFunctionDataHelper<AggregateFunctionForEachData, AggregateFunctionForEach>;

    AggregateFunctionPtr nested_function;

    const size_t nested_size_of_data;

    const size_t num_arguments;

    AggregateFunctionForEachData& ensure_aggregate_data(AggregateDataPtr __restrict place,

                                                        size_t new_size, Arena& arena) const {

        AggregateFunctionForEachData& state = data(place);

        /// Ensure we have aggregate states for new_size elements, allocate

        /// from arena if needed. When reallocating, we can't copy the

        /// states to new buffer with memcpy, because they may contain pointers

        /// to themselves. In particular, this happens when a state contains

        /// a PODArrayWithStackMemory, which stores small number of elements

        /// inline. This is why we create new empty states in the new buffer,

        /// and merge the old states to them.

        size_t old_size = state.dynamic_array_size;

        if (old_size < new_size) {

            static constexpr size_t MAX_ARRAY_SIZE = 100 * 1000000000ULL;

            if (new_size > MAX_ARRAY_SIZE) {

                throw Exception(ErrorCode::INTERNAL_ERROR,

                                "Suspiciously large array size ({}) in -ForEach aggregate function",

                                new_size);

            }

            size_t allocation_size = 0;

            if (common::mul_overflow(new_size, nested_size_of_data, allocation_size)) {

                throw Exception(ErrorCode::INTERNAL_ERROR,

                                "Allocation size ({} * {}) overflows in -ForEach aggregate "

                                "function, but it should've been prevented by previous checks",

                                new_size, nested_size_of_data);

            }

            char* old_state = state.array_of_aggregate_datas;

            char* new_state =

                    arena.aligned_alloc(allocation_size, nested_function->align_of_data());

            size_t i;

            try {

                for (i = 0; i < new_size; ++i) {

                    nested_function->create(&new_state[i * nested_size_of_data]);

                }

            } catch (...) {

                size_t cleanup_size = i;

                for (i = 0; i < cleanup_size; ++i) {

                    nested_function->destroy(&new_state[i * nested_size_of_data]);

                }

                throw;

            }

            for (i = 0; i < old_size; ++i) {

                nested_function->merge(&new_state[i * nested_size_of_data],

                                       &old_state[i * nested_size_of_data], arena);

                nested_function->destroy(&old_state[i * nested_size_of_data]);

            }

            state.array_of_aggregate_datas = new_state;

            state.dynamic_array_size = new_size;

        }

        return state;

    }

public:

    constexpr static auto AGG_FOREACH_SUFFIX = "_foreach";

    AggregateFunctionForEach(AggregateFunctionPtr nested_function_, const DataTypes& arguments)

            : Base(arguments),

              nested_function {std::move(nested_function_)},

              nested_size_of_data(nested_function->size_of_data()),

              num_arguments(arguments.size()) {

        if (arguments.empty()) {

            throw Exception(ErrorCode::INTERNAL_ERROR,

                            "Aggregate function {} require at least one argument", get_name());

        }

    }

    void set_version(const int version_) override {

        Base::set_version(version_);

        nested_function->set_version(version_);

    }

    String get_name() const override { return nested_function->get_name() + AGG_FOREACH_SUFFIX; }

    DataTypePtr get_return_type() const override {

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

    }

    void destroy(AggregateDataPtr __restrict place) const noexcept override {

        AggregateFunctionForEachData& state = data(place);

        char* nested_state = state.array_of_aggregate_datas;

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

            nested_function->destroy(nested_state);

            nested_state += nested_size_of_data;

        }

    }

    bool is_trivial() const override {

        return std::is_trivial_v<Data> && nested_function->is_trivial();

    }

    void merge(AggregateDataPtr __restrict place, ConstAggregateDataPtr rhs,

               Arena& arena) const override {

        const AggregateFunctionForEachData& rhs_state = data(rhs);

        AggregateFunctionForEachData& state =

                ensure_aggregate_data(place, rhs_state.dynamic_array_size, arena);

        const char* rhs_nested_state = rhs_state.array_of_aggregate_datas;

        char* nested_state = state.array_of_aggregate_datas;

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

            nested_function->merge(nested_state, rhs_nested_state, arena);

            rhs_nested_state += nested_size_of_data;

            nested_state += nested_size_of_data;

        }

    }

    void serialize(ConstAggregateDataPtr __restrict place, BufferWritable& buf) const override {

        const AggregateFunctionForEachData& state = data(place);

        buf.write_binary(state.dynamic_array_size);

        const char* nested_state = state.array_of_aggregate_datas;

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

            nested_function->serialize(nested_state, buf);

            nested_state += nested_size_of_data;

        }

    }

    void deserialize(AggregateDataPtr __restrict place, BufferReadable& buf,

                     Arena& arena) const override {

        AggregateFunctionForEachData& state = data(place);

        size_t new_size = 0;

        buf.read_binary(new_size);

        ensure_aggregate_data(place, new_size, arena);

        char* nested_state = state.array_of_aggregate_datas;

        for (size_t i = 0; i < new_size; ++i) {

            nested_function->deserialize(nested_state, buf, arena);

            nested_state += nested_size_of_data;

        }

    }

    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_to = arr_to.get_data();

        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);

            nested_state += nested_size_of_data;

        }

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

    }

    void add(AggregateDataPtr __restrict place, const IColumn** columns, ssize_t row_num,

             Arena& arena) const override {

        std::vector<const IColumn*> nested(num_arguments);

        for (size_t i = 0; i < num_arguments; ++i) {

            nested[i] = &assert_cast<const ColumnArray&, TypeCheckOnRelease::DISABLE>(*columns[i])

                                 .get_data();

        }

        const auto& first_array_column =

                assert_cast<const ColumnArray&, TypeCheckOnRelease::DISABLE>(*columns[0]);

        const auto& offsets = first_array_column.get_offsets();

        size_t begin = offsets[row_num - 1];

        size_t end = offsets[row_num];

        /// Sanity check. NOTE We can implement specialization for a case with single argument, if the check will hurt performance.

        for (size_t i = 1; i < num_arguments; ++i) {

            const auto& ith_column =

                    assert_cast<const ColumnArray&, TypeCheckOnRelease::DISABLE>(*columns[i]);

            const auto& ith_offsets = ith_column.get_offsets();

            if (ith_offsets[row_num] != end ||

                (row_num != 0 && ith_offsets[row_num - 1] != begin)) {

                throw Exception(ErrorCode::INTERNAL_ERROR,

                                "Arrays passed to {} aggregate function have different sizes",

                                get_name());

            }

        }

        AggregateFunctionForEachData& state = ensure_aggregate_data(place, end - begin, arena);

        char* nested_state = state.array_of_aggregate_datas;

        for (size_t i = begin; i < end; ++i) {

            nested_function->add(nested_state, nested.data(), i, arena);

            nested_state += nested_size_of_data;

        }

    }

};

} // namespace doris