// 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/data_type/data_type.h"

#include "exprs/aggregate/aggregate_function.h"

#include "exprs/aggregate/aggregate_function_simple_factory.h"

#include "exprs/aggregate/aggregate_function_statistic.h"

#include "exprs/aggregate/factory_helpers.h"

#include "exprs/aggregate/helpers.h"

namespace doris {

AggregateFunctionPtr create_aggregate_function_skew(const std::string& name,

                                                    const DataTypes& argument_types,

                                                    const DataTypePtr& result_type,

                                                    const bool result_is_nullable,

                                                    const AggregateFunctionAttr& attr) {

    assert_arity_range(name, argument_types, 1, 1);

    if (!result_is_nullable) {

        throw doris::Exception(ErrorCode::INTERNAL_ERROR,

                               "Aggregate function {} requires result_is_nullable", name);

    }

    const bool nullable_input = argument_types[0]->is_nullable();

    using StatFunctionTemplate = StatFuncOneArg<TYPE_DOUBLE, 3>;

    if (nullable_input) {

        return creator_without_type::create_ignore_nullable<

                AggregateFunctionVarianceSimple<StatFunctionTemplate, true>>(

                argument_types, result_is_nullable, attr, STATISTICS_FUNCTION_KIND::SKEW_POP);

    } else {

        return creator_without_type::create_ignore_nullable<

                AggregateFunctionVarianceSimple<StatFunctionTemplate, false>>(

                argument_types, result_is_nullable, attr, STATISTICS_FUNCTION_KIND::SKEW_POP);

    }

}

void register_aggregate_function_skewness(AggregateFunctionSimpleFactory& factory) {

    factory.register_function_both("skew", create_aggregate_function_skew);

    factory.register_alias("skew", "skew_pop");

    factory.register_alias("skew", "skewness");

}

} // namespace doris