// 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 <glog/logging.h>

#include <memory>

#include "core/data_type/data_type_number.h"

#include "core/data_type/primitive_type.h"

#include "exprs/aggregate/aggregate_function.h"

#include "util/reservoir_sampler.h"

namespace doris {

class Arena;

class BufferReadable;

struct QuantileReservoirSampler {

    void add(const double x, const double input_level) {

        this->level = input_level;

        data.insert(x);

    }

    void merge(const QuantileReservoirSampler& rhs) {

        level = rhs.level;

        data.merge(rhs.data);

    }

    void reset() {

        level = 0.0;

        data.clear();

    }

    void serialize(BufferWritable& buf) const {

        buf.write_binary(level);

        data.write(buf);

    }

    void deserialize(BufferReadable& buf) {

        buf.read_binary(level);

        data.read(buf);

    }

    double get() const {

        // The caller is a ConstAggregateDataPtr, but it itself is an AggregateDataPtr.

        // To call a non-const method here, a const_cast is required.

        return const_cast<ReservoirSampler&>(data).quantileInterpolated(this->level);

    }

private:

    double level = 0.0;

    ReservoirSampler data;

};

template <typename Data>

class AggregateFunctionPercentileReservoir final

        : public IAggregateFunctionDataHelper<Data, AggregateFunctionPercentileReservoir<Data>>,

          MultiExpression,

          NullableAggregateFunction {

public:

    AggregateFunctionPercentileReservoir(const DataTypes& argument_types_)

            : IAggregateFunctionDataHelper<Data, AggregateFunctionPercentileReservoir<Data>>(

                      argument_types_) {}

    String get_name() const override { return "percentile_reservoir"; }

    DataTypePtr get_return_type() const override { return std::make_shared<DataTypeFloat64>(); }

    void add(AggregateDataPtr __restrict place, const IColumn** columns, ssize_t row_num,

             Arena&) const override {

        auto value = assert_cast<const ColumnFloat64&>(*columns[0]).get_data()[row_num];

        auto level = assert_cast<const ColumnFloat64&>(*columns[1]).get_data()[0];

        this->data(place).add(value, level);

    }

    void reset(AggregateDataPtr place) const override { this->data(place).reset(); }

    void merge(AggregateDataPtr __restrict place, ConstAggregateDataPtr rhs,

               Arena&) const override {

        this->data(place).merge(this->data(rhs));

    }

    void serialize(ConstAggregateDataPtr __restrict place, BufferWritable& buf) const override {

        this->data(place).serialize(buf);

    }

    void deserialize(AggregateDataPtr __restrict place, BufferReadable& buf,

                     Arena&) const override {

        this->data(place).deserialize(buf);

    }

    void insert_result_into(ConstAggregateDataPtr __restrict place, IColumn& to) const override {

        assert_cast<ColumnFloat64&>(to).get_data().push_back(this->data(place).get());

    }

};

} // namespace doris