#pragma once

#include <functional>

#include <algorithm/fast_power.hpp>
#include <macros.h>

struct integrand_handle_base {
    virtual ~integrand_handle_base() = default;

    virtual double f(double x, double y, double z) const = 0;
    virtual double w() const                             = 0;
    virtual double w_without_grad() const                = 0;

    virtual bool strict_polynomial() const = 0;
};

// struct SIv2_API common_integrand_handle final : public integrand_handle_base {
//     virtual ~common_integrand_handle() = default;

//     virtual double f(double x, double y, double z) const { return handle(x, y, z); }

//     virtual double w() const { return 1.; }

//     virtual bool strict_polynomial() const { return false; }

//     std::function<double(double, double, double)> handle{};
// };

struct SIv2_API polynomial_integrand_handle final : public integrand_handle_base {
    virtual ~polynomial_integrand_handle() = default;

    virtual double f(double x, double y, double z) const
    {
        return algorithm::fast_power(x, p1) * algorithm::fast_power(y, p2) * algorithm::fast_power(z, p3);
    }

    virtual double w() const { return coeff / (p1 + p2 + p3 + 3); }

    virtual double w_without_grad() const { return coeff; }

    virtual bool strict_polynomial() const { return true; }

    double  coeff{};
    uint8_t p1{}, p2{}, p3{};
};