1 files changed, 71 insertions, 0 deletions
diff --git a/temperature.go b/temperature.go
new file mode 100644
index 0000000..89cb1ba
--- /dev/null
+++ b/temperature.go
@@ -0,0 +1,71 @@
+package main
+
+import (
+	"errors"
+	"fmt"
+)
+
+type temperatureUnit int
+
+const (
+	celcius temperatureUnit = iota
+	kelvin
+	fahrenheit
+)
+
+// temperatureUnitStrings returns a slice of strings, each representing a
+// temperatureUnit.
+// This is necessary because giu.Combo only works with strings.
+func temperatureUnitStrings() []string {
+	return []string{"°C", "°K", "°F"}
+}
+
+const (
+	defaultTemperatureUnit temperatureUnit = celcius
+	// Used to index temperatureUnitStrings
+	defaultTemperatureUnitIndex int32 = 0 // celcius
+)
+
+func temperatureUnitFromString(s string) (temperatureUnit, error) {
+	// Each case corresponds to a value in volumeUnitStrings.
+	switch s {
+	case "°C":
+		return celcius, nil
+	case "°K":
+		return kelvin, nil
+	case "°F":
+		return fahrenheit, nil
+	default:
+		return *new(temperatureUnit), errors.New(fmt.Sprintf("invalid temperatureUnit: '%s'", s))
+	}
+}
+
+type temperature struct {
+	val  float32
+	unit temperatureUnit
+}
+
+func (t temperature) asUnit(u temperatureUnit) (float32, error) {
+	// Convert to celcius
+	var c float32
+	switch t.unit {
+	case celcius:
+		c = t.val
+	case kelvin:
+		c = t.val - 272.15
+	case fahrenheit:
+		c = (t.val - 32.0) * (5.0 / 9.0)
+	}
+
+	// Convert to desired unit
+	switch u {
+	case celcius:
+		return c, nil
+	case kelvin:
+		return c + 272.15, nil
+	case fahrenheit:
+		return c * (9.0 / 5.0) + 32.0, nil
+	default:
+		return 0, errors.New(fmt.Sprintf("invalid temperatureUnit: '%v'", u))
+	}
+}