// 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/Functions/array/arrayIndex.h

// and modified by Doris

#include <stddef.h>

#include <memory>

#include <utility>

#include "common/status.h"

#include "core/block/block.h"

#include "core/block/column_numbers.h"

#include "core/block/column_with_type_and_name.h"

#include "core/column/column.h"

#include "core/column/column_array.h"

#include "core/column/column_nullable.h"

#include "core/data_type/data_type.h"

#include "core/data_type/data_type_nullable.h"

#include "core/types.h"

#include "exprs/aggregate/aggregate_function.h"

#include "exprs/function/function.h"

#include "exprs/function/simple_function_factory.h"

namespace doris {

class FunctionContext;

} // namespace doris

namespace doris {

class FunctionArrayPushfront : public IFunction {

public:

    static constexpr auto name = "array_pushfront";

    static FunctionPtr create() { return std::make_shared<FunctionArrayPushfront>(); }

    String get_name() const override { return name; }

    bool is_variadic() const override { return false; }

    size_t get_number_of_arguments() const override { return 2; }

    bool use_default_implementation_for_nulls() const override { return false; }

    DataTypePtr get_return_type_impl(const DataTypes& arguments) const override {

        // the type of arguments[0] could be Array(Nullable(xxx)) or Nullable(Array(Nullable(xxx))),

        // and we always return Nullable(Array(Nullable(xxx)))

        return std::make_shared<DataTypeNullable>(remove_nullable(arguments[0]));

    }

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

                        uint32_t result, size_t input_rows_count) const override {

        auto src_column =

                block.get_by_position(arguments[0]).column->convert_to_full_column_if_const();

        // extract src array column

        const ColumnArray* array_column = nullptr;

        const UInt8* array_null_map = nullptr;

        if (src_column->is_nullable()) {

            auto nullable_array = static_cast<const ColumnNullable*>(src_column.get());

            array_column = static_cast<const ColumnArray*>(&nullable_array->get_nested_column());

            array_null_map = nullable_array->get_null_map_column().get_data().data();

        } else {

            array_column = static_cast<const ColumnArray*>(src_column.get());

        }

        auto& src_nested_data_col = array_column->get_data();

        auto& src_offset_col = array_column->get_offsets();

        auto right_column =

                block.get_by_position(arguments[1]).column->convert_to_full_column_if_const();

        // prepare dst nullable array column

        auto result_col = block.get_by_position(result).type->create_column();

        auto result_nullable_col = static_cast<ColumnNullable*>(result_col.get());

        auto& result_null_map = result_nullable_col->get_null_map_data();

        auto result_array_col =

                static_cast<ColumnArray*>(result_nullable_col->get_nested_column_ptr().get());

        auto& result_nested_data_col = result_array_col->get_data();

        auto& result_offset_col = result_array_col->get_offsets();

        result_null_map.resize(input_rows_count);

        result_offset_col.resize(input_rows_count);

        result_nested_data_col.reserve(src_nested_data_col.size() + input_rows_count);

        size_t off = 0;

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

            if (array_null_map && array_null_map[i]) {

                result_null_map[i] = 1;

                result_offset_col[i] = off;

                continue;

            }

            size_t length = src_offset_col[i] - src_offset_col[i - 1];

            result_nested_data_col.insert((*right_column)[i]);

            result_nested_data_col.insert_range_from(src_nested_data_col, src_offset_col[i - 1],

                                                     length);

            off += length + 1;

            result_null_map[i] = 0;

            result_offset_col[i] = off;

        }

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

        return Status::OK();

    }

};

void register_function_array_pushfront(SimpleFunctionFactory& factory) {

    factory.register_function<FunctionArrayPushfront>();

}

} // namespace doris