// 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.

#pragma once

#include <fmt/format.h>

#include "common/status.h"

#include "core/arena.h"

#include "core/block/block.h"

#include "core/block/columns_with_type_and_name.h"

#include "core/column/column.h"

#include "core/column/column_const.h"

#include "core/column/column_nullable.h"

#include "core/data_type/data_type.h"

#include "core/data_type/data_type_agg_state.h"

#include "core/types.h"

#include "exprs/aggregate/aggregate_function.h"

#include "exprs/function/function.h"

namespace doris {

class FunctionAggState : public IFunction {

public:

    FunctionAggState(const DataTypes& argument_types, const DataTypePtr& return_type,

                     AggregateFunctionPtr agg_function)

            : _argument_types(argument_types),

              _return_type(return_type),

              _agg_function(agg_function),

              _always_const_argument_idx(argument_types.size(), false) {

        for (auto index : _agg_function->get_const_argument_indexes()) {

            DORIS_CHECK_LT(index, _always_const_argument_idx.size());

            _always_const_argument_idx[index] = true;

        }

    }

    static FunctionBasePtr create(const DataTypes& argument_types, const DataTypePtr& return_type,

                                  AggregateFunctionPtr agg_function) {

        if (agg_function == nullptr) {

            return nullptr;

        }

        return std::make_shared<DefaultFunction>(

                std::make_shared<FunctionAggState>(argument_types, return_type, agg_function),

                argument_types, return_type);

    }

    size_t get_number_of_arguments() const override { return _argument_types.size(); }

    bool use_default_implementation_for_nulls() const override { return false; }

    String get_name() const override { return fmt::format("{}_state", _agg_function->get_name()); }

    DataTypePtr get_return_type_impl(const DataTypes& arguments) const override {

        return _return_type;

    }

    const std::vector<size_t>& get_const_argument_indexes() const override {

        return _agg_function->get_const_argument_indexes();

    }

    Status execute_impl(FunctionContext* context, Block& block, const ColumnNumbers& arguments,

                        uint32_t result, size_t input_rows_count) const override {

        auto col = _agg_function->create_serialize_column();

        std::vector<const IColumn*> agg_columns;

        std::vector<ColumnPtr> save_columns;

        for (size_t i = 0; i < arguments.size(); i++) {

            DataTypePtr signature =

                    assert_cast<const DataTypeAggState*>(_return_type.get())->get_sub_types()[i];

            ColumnPtr column;

            if (_always_const_argument_idx[i]) {

                column = block.get_by_position(arguments[i]).column;

                if (const auto* const_column = check_and_get_column<ColumnConst>(*column)) {

                    column = const_column->get_data_column_ptr();

                }

                column = ColumnConst::create(std::move(column), input_rows_count);

            } else {

                column = block.get_by_position(arguments[i])

                                 .column->convert_to_full_column_if_const();

            }

            save_columns.push_back(column);

            if (!signature->is_nullable() && column->is_nullable()) {

                return Status::InternalError(

                        "State function meet input nullable column, but signature is not nullable");

            }

            if (!column->is_nullable() && signature->is_nullable()) {

                column = make_nullable(column);

                save_columns.push_back(column);

            }

            agg_columns.push_back(column.get());

        }

        _agg_function->check_input_columns_type(agg_columns.data());

        _agg_function->streaming_agg_serialize_to_column(agg_columns.data(), col, input_rows_count,

                                                         context->get_arena());

        block.replace_by_position(result, std::move(col));

        return Status::OK();

    }

private:

    DataTypes _argument_types;

    DataTypePtr _return_type;

    AggregateFunctionPtr _agg_function;

    // Bool map of argument positions that must be constant by aggregate semantics.

    // FE checks these positions before execution.

    std::vector<bool> _always_const_argument_idx;

};

} // namespace doris