package units

import (
	"math"

	"gitea.maximumdirect.net/ejr/weatherapi/internal/platform/constants"
)

type Converter interface {
	TemperatureCToOutput(celsius *float64) *float64
	SpeedKmhToOutput(kmh *float64) *float64
	System() string
}

type USConverter struct{}

func (USConverter) System() string {
	return "us"
}

func (USConverter) TemperatureCToOutput(celsius *float64) *float64 {
	if celsius == nil {
		return nil
	}
	f := round(constants.CelsiusToFahrenheit(*celsius), constants.TempFahrenheitPrecision)
	return &f
}

func (USConverter) SpeedKmhToOutput(kmh *float64) *float64 {
	if kmh == nil {
		return nil
	}
	mph := round(constants.KmhToMph(*kmh), constants.WindMphPrecision)
	return &mph
}

type MetricConverter struct{}

func (MetricConverter) System() string {
	return "metric"
}

func (MetricConverter) TemperatureCToOutput(celsius *float64) *float64 {
	return clone(celsius)
}

func (MetricConverter) SpeedKmhToOutput(kmh *float64) *float64 {
	return clone(kmh)
}

func clone(v *float64) *float64 {
	if v == nil {
		return nil
	}
	out := *v
	return &out
}

func round(v float64, precision int) float64 {
	pow := math.Pow(10, float64(precision))
	return math.Round(v*pow) / pow
}