// SPDX-License-Identifier: GPL-2.0
#include "units.h"
#include "gettext.h"
#include "pref.h"

const struct units SI_units = SI_UNITS;
const struct units IMPERIAL_units = {
        .length = units::FEET, .volume = units::CUFT, .pressure = units::PSI, .temperature = units::FAHRENHEIT, .weight = units::LBS,
	.vertical_speed_time = units::MINUTES, .duration_units = units::MIXED, .show_units_table = false
};

int get_pressure_units(int mb, const char **units)
{
	int pressure;
	const char *unit;
	const struct units *units_p = get_units();

	switch (units_p->pressure) {
	case units::BAR:
	default:
		pressure = (mb + 500) / 1000;
		unit = translate("gettextFromC", "bar");
		break;
	case units::PSI:
		pressure = int_cast<int>(mbar_to_PSI(mb));
		unit = translate("gettextFromC", "psi");
		break;
	}
	if (units)
		*units = unit;
	return pressure;
}

double get_temp_units(unsigned int mk, const char **units)
{
	double deg;
	const char *unit;
	const struct units *units_p = get_units();

	if (units_p->temperature == units::FAHRENHEIT) {
		deg = mkelvin_to_F(mk);
		unit = "°F";
	} else {
		deg = mkelvin_to_C(mk);
		unit = "°C";
	}
	if (units)
		*units = unit;
	return deg;
}

double get_volume_units(unsigned int ml, int *frac, const char **units)
{
	int decimals;
	double vol;
	const char *unit;
	const struct units *units_p = get_units();

	switch (units_p->volume) {
	case units::LITER:
	default:
		vol = ml / 1000.0;
		unit = translate("gettextFromC", "ℓ");
		decimals = 1;
		break;
	case units::CUFT:
		vol = ml_to_cuft(ml);
		unit = translate("gettextFromC", "cuft");
		decimals = 2;
		break;
	}
	if (frac)
		*frac = decimals;
	if (units)
		*units = unit;
	return vol;
}

int units_to_sac(double volume)
{
	if (get_units()->volume == units::CUFT)
		return lrint(cuft_to_l(volume) * 1000.0);
	else
		return lrint(volume * 1000);
}

depth_t units_to_depth(double depth)
{
	depth_t internaldepth;
	if (get_units()->length == units::METERS) {
		internaldepth.mm = lrint(depth * 1000);
	} else {
		internaldepth.mm = feet_to_mm(depth);
	}
	return internaldepth;
}

double get_depth_units(int mm, int *frac, const char **units)
{
	int decimals;
	double d;
	const char *unit;
	const struct units *units_p = get_units();

	switch (units_p->length) {
	case units::METERS:
	default:
		d = mm / 1000.0;
		unit = translate("gettextFromC", "m");
		decimals = d < 20;
		break;
	case units::FEET:
		d = mm_to_feet(mm);
		unit = translate("gettextFromC", "ft");
		decimals = 0;
		break;
	}
	if (frac)
		*frac = decimals;
	if (units)
		*units = unit;
	return d;
}

double get_vertical_speed_units(unsigned int mms, int *frac, const char **units)
{
	double d;
	const char *unit;
	const struct units *units_p = get_units();
	const double time_factor = units_p->vertical_speed_time == units::MINUTES ? 60.0 : 1.0;

	switch (units_p->length) {
	case units::METERS:
	default:
		d = mms / 1000.0 * time_factor;
		if (units_p->vertical_speed_time == units::MINUTES)
			unit = translate("gettextFromC", "m/min");
		else
			unit = translate("gettextFromC", "m/s");
		break;
	case units::FEET:
		d = mm_to_feet(mms) * time_factor;
		if (units_p->vertical_speed_time == units::MINUTES)
			unit = translate("gettextFromC", "ft/min");
		else
			unit = translate("gettextFromC", "ft/s");
		break;
	}
	if (frac)
		*frac = d < 10;
	if (units)
		*units = unit;
	return d;
}

double get_weight_units(unsigned int grams, int *frac, const char **units)
{
	int decimals;
	double value;
	const char *unit;
	const struct units *units_p = get_units();

	if (units_p->weight == units::LBS) {
		value = grams_to_lbs(grams);
		unit = translate("gettextFromC", "lbs");
		decimals = 0;
	} else {
		value = grams / 1000.0;
		unit = translate("gettextFromC", "kg");
		decimals = 1;
	}
	if (frac)
		*frac = decimals;
	if (units)
		*units = unit;
	return value;
}

const struct units *get_units()
{
	return &prefs.units;
}

// Calculate the distance in meters between two coordinates.
unsigned int get_distance(location_t loc1, location_t loc2)
{
	double lat1_r = udeg_to_radians(loc1.lat.udeg);
	double lat2_r = udeg_to_radians(loc2.lat.udeg);
	double lat_d_r = udeg_to_radians(loc2.lat.udeg - loc1.lat.udeg);
	double lon_d_r = udeg_to_radians(loc2.lon.udeg - loc1.lon.udeg);

	double a = sin(lat_d_r/2) * sin(lat_d_r/2) +
		cos(lat1_r) * cos(lat2_r) * sin(lon_d_r/2) * sin(lon_d_r/2);
	if (a < 0.0) a = 0.0;
	if (a > 1.0) a = 1.0;
	double c = 2 * atan2(sqrt(a), sqrt(1.0 - a));

	// Earth radius in metres
	return lrint(6371000 * c);
}