#pragma once

#include <array>
#include <cstdint>

#include <libavr/flash.hpp>

// The auto-mode fan curve, tabulated at compile time as a flash_table of duty
// percent per C: a cubic that is held at zero below the temperature the fan
// starts at.
namespace app::curve {

inline constexpr double cubic_term = 0.002246;
inline constexpr double square_term = -0.09;
inline constexpr double linear_term = 0.91;
inline constexpr std::int8_t start_celsius = 20;

namespace detail {

consteval std::uint8_t duty_entry(std::int32_t celsius)
{
	double x = celsius;
	if (x < start_celsius) {
		return 0;
	}
	double duty = cubic_term * x * x * x + square_term * x * x + linear_term * x;
	if (duty < 0) {
		duty = 0;
	}
	if (duty > 100) {
		duty = 100;
	}
	return static_cast<std::uint8_t>(duty + 0.5);
}

inline constexpr avr::flash_table<[] {
	std::array<std::uint8_t, 100> out{};
	for (std::int32_t t = 0; t < static_cast<std::int32_t>(out.size()); ++t) {
		out[static_cast<std::size_t>(t)] = duty_entry(t);
	}
	return out;
}()>
    table;

} // namespace detail

// Duty percent for a temperature, clamped to the table's own window.
inline std::uint8_t duty(std::int8_t celsius)
{
	constexpr auto highest = static_cast<std::int8_t>(detail::table.size() - 1);
	if (celsius < 0) {
		celsius = 0;
	}
	if (celsius > highest) {
		celsius = highest;
	}
	return detail::table[static_cast<std::uint8_t>(celsius)];
}

} // namespace app::curve