// 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 "core/column/column_array.h"

#include "core/column/column_nullable.h"

#include "core/data_type/data_type_array.h"

#include "core/data_type/data_type_number.h"

#include "exprs/function/function.h"

#include "exprs/function/function_helpers.h"

#include "exprs/function/simple_function_factory.h"

namespace doris {

// array_count([0, 1, 1, 1, 0, 0]) -> [3]

class FunctionArrayCount : public IFunction {

public:

    static constexpr auto name = "array_count";

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

    String get_name() const override { return name; }

    bool is_variadic() const override { return false; }

    size_t get_number_of_arguments() const override { return 1; }

    bool use_default_implementation_for_nulls() const override { return false; }

    ColumnNumbers get_arguments_that_are_always_constant() const override { return {1}; }

    DataTypePtr get_return_type_impl(const DataTypes& arguments) const override {

        return std::make_shared<DataTypeInt64>();

    }

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

                        uint32_t result, size_t input_rows_count) const override {

        const auto& [src_column, src_const] =

                unpack_if_const(block.get_by_position(arguments[0]).column);

        const ColumnArray* array_column = nullptr;

        const UInt8* array_null_map = nullptr;

        if (src_column->is_nullable()) {

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

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

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

        } else {

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

        }

        if (!array_column) {

            return Status::RuntimeError("unsupported types for function {}({})", get_name(),

                                        block.get_by_position(arguments[0]).type->get_name());

        }

        const auto& offsets = array_column->get_offsets();

        ColumnPtr nested_column = nullptr;

        const UInt8* nested_null_map = nullptr;

        if (array_column->get_data().is_nullable()) {

            const auto& nested_null_column =

                    assert_cast<const ColumnNullable&>(array_column->get_data());

            nested_null_map = nested_null_column.get_null_map_column().get_data().data();

            nested_column = nested_null_column.get_nested_column_ptr();

        } else {

            nested_column = array_column->get_data_ptr();

        }

        const auto& nested_data = assert_cast<const ColumnUInt8&>(*nested_column).get_data();

        auto dst_column = ColumnInt64::create(offsets.size());

        auto& dst_data = dst_column->get_data();

        for (size_t row = 0; row < offsets.size(); ++row) {

            Int64 res = 0;

            if (array_null_map && array_null_map[row]) {

                dst_data[row] = res;

                continue;

            }

            size_t off = offsets[row - 1];

            size_t len = offsets[row] - off;

            for (size_t pos = 0; pos < len; ++pos) {

                if (nested_null_map && nested_null_map[pos + off]) {

                    continue;

                }

                if (nested_data[pos + off] != 0) {

                    ++res;

                }

            }

            dst_data[row] = res;

        }

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

        return Status::OK();

    }

};

void register_function_array_count(SimpleFunctionFactory& factory) {

    factory.register_function<FunctionArrayCount>();

}

} // namespace doris