From 0c5d33fc817047ab2c2c9dd3ed6784c032755819 Mon Sep 17 00:00:00 2001
From: sam-anthony <samanthony6@protonmail.com>
Date: Sat, 26 Mar 2022 15:56:22 -0230
Subject: intake air temperature

---
 main.go        | 27 +++++++++++++++++-----
 pressure.go    |  4 ----
 temperature.go | 71 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 ui.go          | 29 ++++++++++++++++++++++++
 4 files changed, 121 insertions(+), 10 deletions(-)
 create mode 100644 temperature.go

diff --git a/main.go b/main.go
index d36ebc8..653fd61 100644
--- a/main.go
+++ b/main.go
@@ -26,14 +26,28 @@ var engineSpeed = [numPoints]int32{2000, 3000, 4000, 5000, 6000, 7000}
 
 var volumetricEfficiency = [numPoints]int32{100, 100, 100, 100, 100, 100}
 
+var (
+	intakeAirTemperature = [numPoints]temperature{
+		{35, celcius},
+		{35, celcius},
+		{35, celcius},
+		{35, celcius},
+		{35, celcius},
+		{35, celcius},
+	}
+
+	// selectedTemperatureUnit is used to index temperatureUnitStrings.
+	selectedTemperatureUnit = defaultTemperatureUnitIndex
+)
+
 var (
 	manifoldPressure = [numPoints]pressure{
-		newPressure(),
-		newPressure(),
-		newPressure(),
-		newPressure(),
-		newPressure(),
-		newPressure(),
+		{100, defaultPressureUnit},
+		{100, defaultPressureUnit},
+		{100, defaultPressureUnit},
+		{100, defaultPressureUnit},
+		{100, defaultPressureUnit},
+		{100, defaultPressureUnit},
 	}
 
 	// selectedPressureUnit is used to index pressureUnitStrings.
@@ -47,6 +61,7 @@ func loop() {
 			Rows(
 				engineSpeedRow(),
 				volumetricEfficiencyRow(),
+				intakeAirTemperatureRow(),
 				manifoldPressureRow(),
 			).
 			Columns(
diff --git a/pressure.go b/pressure.go
index 74f035d..f486552 100644
--- a/pressure.go
+++ b/pressure.go
@@ -48,10 +48,6 @@ type pressure struct {
 	unit pressureUnit
 }
 
-func newPressure() pressure {
-	return pressure{100, defaultPressureUnit}
-}
-
 func (p pressure) asUnit(u pressureUnit) float32 {
 	pa := p.val * float32(p.unit) // Convert to pascals.
 	return pa / float32(u)        // Convert to desired unit.
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))
+	}
+}
diff --git a/ui.go b/ui.go
index dd12b06..57765a3 100644
--- a/ui.go
+++ b/ui.go
@@ -50,6 +50,35 @@ func volumetricEfficiencyRow() *g.TableRowWidget {
 	)
 }
 
+func intakeAirTemperatureRow() *g.TableRowWidget {
+	return g.TableRow(
+		g.Label("Intake Air Temperature"),
+		g.Combo(
+			"",
+			temperatureUnitStrings()[selectedTemperatureUnit],
+			temperatureUnitStrings(),
+			&selectedTemperatureUnit,
+		).
+			OnChange(func() {
+				s := temperatureUnitStrings()[selectedTemperatureUnit]
+				u, err := temperatureUnitFromString(s)
+				check(err)
+
+				for i := range intakeAirTemperature {
+					t, err := intakeAirTemperature[i].asUnit(u)
+					check(err)
+					intakeAirTemperature[i] = temperature{t, u}
+				}
+			}),
+		g.InputFloat(&intakeAirTemperature[0].val).Format("%.2f"),
+		g.InputFloat(&intakeAirTemperature[1].val).Format("%.2f"),
+		g.InputFloat(&intakeAirTemperature[2].val).Format("%.2f"),
+		g.InputFloat(&intakeAirTemperature[3].val).Format("%.2f"),
+		g.InputFloat(&intakeAirTemperature[4].val).Format("%.2f"),
+		g.InputFloat(&intakeAirTemperature[5].val).Format("%.2f"),
+	)
+}
+
 func manifoldPressureRow() *g.TableRowWidget {
 	return g.TableRow(
 		g.Label("Manifold Absolute Pressure"),
-- 
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