// 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.

#include <glog/logging.h>

#include <cstddef>

#include <memory>

#include <ostream>

#include <string>

#include <utility>

#include <vector>

#include "common/status.h"

#include "core/assert_cast.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/data_type/data_type.h"

#include "core/data_type/data_type_array.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 {

// array_concat([1, 2], [7, 8], [5, 6]) -> [1, 2, 7, 8, 5, 6]

class FunctionArrayConcat : public IFunction {

public:

    static constexpr auto name = "array_concat";

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

    String get_name() const override { return name; }

    bool is_variadic() const override { return true; }

    size_t get_number_of_arguments() const override { return 1; }

    DataTypePtr get_return_type_impl(const DataTypes& arguments) const override {

        DCHECK(arguments.size() > 0)

                << "function: " << get_name() << ", arguments should not be empty";

        for (const auto& arg : arguments) {

            DCHECK(arg->get_primitive_type() == TYPE_ARRAY)

                    << "argument for function array_concat should be DataTypeArray"

                    << " and argument is " << arg->get_name();

        }

        return arguments[0];

    }

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

                        const uint32_t result, size_t input_rows_count) const override {

        DataTypePtr column_type = block.get_by_position(arguments[0]).type;

        auto nested_type = assert_cast<const DataTypeArray&>(*column_type).get_nested_type();

        auto result_column = ColumnArray::create(nested_type->create_column(),

                                                 ColumnArray::ColumnOffsets::create());

        IColumn& result_nested_col = result_column->get_data();

        ColumnArray::Offsets64& column_offsets = result_column->get_offsets();

        column_offsets.resize(input_rows_count);

        size_t total_size = 0;

        for (size_t col : arguments) {

            ColumnPtr src_column =

                    block.get_by_position(col).column->convert_to_full_column_if_const();

            const auto& src_column_array = check_and_get_column<ColumnArray>(*src_column);

            total_size += src_column_array->get_data().size();

        }

        result_nested_col.reserve(total_size);

        size_t off = 0;

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

            for (size_t col : arguments) {

                ColumnPtr src_column =

                        block.get_by_position(col).column->convert_to_full_column_if_const();

                const auto& src_column_array = check_and_get_column<ColumnArray>(*src_column);

                const auto& src_column_offsets = src_column_array->get_offsets();

                const size_t length = src_column_offsets[row] - src_column_offsets[row - 1];

                result_nested_col.insert_range_from(src_column_array->get_data(),

                                                    src_column_offsets[row - 1], length);

                off += length;

            }

            column_offsets[row] = off;

        }

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

        return Status::OK();

    }

};

void register_function_array_concat(SimpleFunctionFactory& factory) {

    factory.register_function<FunctionArrayConcat>();

}

} // namespace doris