#ifndef BAROMETERDATA_H
#define BAROMETERDATA_H


#include <cmath>
#include "../../math/Floatingpoint.h"

/** data received from a barometer sensor */
struct BarometerData {

	FPDefault hPa;

	explicit BarometerData() : hPa(0) {;}

	explicit BarometerData(const FPDefault hPa) : hPa(hPa) {;}

	/** valid data? */
	bool isValid() const {
		return !std::isnan(hPa);
	}

	bool operator == (const BarometerData& o ) const {
		return EQ_OR_NAN(hPa, o.hPa);
	}

public:

	static constexpr double R = 8.31447;	// universal gas constant for air,		newton meter / mol kelvin
	static constexpr double L = 0.0065;	// standard temperature lapse rate,			degree kelven per meter
	static constexpr double g = 9.80665;	// gravity constant,					meter per square second
	static constexpr double M = 0.0289644;	// molar mass for dry air,				kg / mol
	static constexpr double P0 = 1013.25;	// pressure at mean sea level,			hPa
	static constexpr double T0 = 288.15;		// temperature at mean sea level,		kelvin

	/** hPa->meter assuming a constant 1013.25 at 0m as reference */
	static FPDefault hpaToMeter(const FPDefault pressure) {
		return static_cast<FPDefault>(
		    (T0/L) * (std::pow(static_cast<FPDouble>(pressure)/P0, -(R*L)/(g*M))-1.0)
		);
	}

	/** hPa->meter by using the given pressure pRef at hRef as reference */
	static FPDefault hpaToMeter(const FPDefault pressure, const FPDefault PRef, const FPDefault hRef) {
		return static_cast<FPDefault>(
		    hRef + (T0/L) * (std::pow(static_cast<FPDouble>(pressure)/PRef, -(R*L)/(g*M))-1.0)
		);
	}

	/** meter->hPa assuming a constant 1013.25 at 0m as reference */
	static FPDefault meterTohPa(const FPDefault altitude) {
		return static_cast<FPDefault>(
		    P0 * std::pow(T0 / (T0+L*altitude), (g*M)/(R*L))
		);
	}

	/**  meter->hPa by using the given pressure pRef at hRef as reference */
	static FPDefault meterTohPa(const FPDefault altitude, const FPDefault PRef, const FPDefault hRef) {
		return static_cast<FPDefault>(
		    PRef * std::pow(T0 / (T0+L*(altitude-hRef)), (g*M)/(R*L))
		);
	}


private:

	static inline bool EQ_OR_NAN(const FPDefault a, const FPDefault b) {return (a==b) || ( (a!=a) && (b!=b) );}

};

#endif // BAROMETERDATA_H