housekeeping: Refactored API to separate packages

translation/mapping.go

@@ -0,0 +1,139 @@
+package translation
+
+import (
+	"fmt"
+	"math"
+
+	"github.com/charmbracelet/log"
+	"gitlab.com/gomidi/midi/v2"
+	"github.com/bendahl/uinput"
+)
+
+// A Mapping is an interface for all types of Mappings.
+type Mapping interface {
+	Is(midi.Message) bool
+	TriggerIfMatch(midi.Message, uinput.Gamepad) error
+	Comment() string
+}
+
+// A ButtonMapping maps a MIDI Note to a gamepad button.
+type ButtonMapping struct {
+	CommentStr string
+	MidiChannel uint8
+	MidiKey uint8
+	GamepadKey int
+}
+
+// Is checks if the MIDI message msg triggers this Mapping, without actually triggering it.
+func (m ButtonMapping) Is(msg midi.Message) bool {
+	var channel, key uint8
+
+	switch {
+	case msg.GetNoteOn(&channel, &key, nil), msg.GetNoteOff(&channel, &key, nil):
+		return (m.MidiChannel == channel && m.MidiKey == key)
+	default:
+		return false
+	}
+}
+
+// TriggerIfMatch checks if the MIDI message msg triggers this Mapping, and if so,
+// sends the corresponding input to virtGamepad.
+func (m ButtonMapping) TriggerIfMatch(msg midi.Message, virtGamepad uinput.Gamepad) error {
+	if m.Is(msg) {
+		var velocity uint8
+		msg.GetNoteOn(nil, nil, &velocity)
+		switch msg.Type() {
+		case midi.NoteOnMsg:
+			if velocity != 0 {
+				log.Debug(m.CommentStr, "status", "down")
+				return virtGamepad.ButtonDown(m.GamepadKey)
+			}
+			fallthrough // if reached here, velocity is 0 -> NoteOff
+		case midi.NoteOffMsg:
+			log.Debug(m.CommentStr, "status", "up")
+			return virtGamepad.ButtonUp(m.GamepadKey)
+		default:
+			return fmt.Errorf("Invalid message type triggered ButtonMapping")
+		}
+	}
+
+	return nil
+}
+
+// Comment returns the Mappings comment.
+func (m ButtonMapping) Comment() string {
+	return m.CommentStr
+}
+
+type ControllerAxis int
+
+const (
+	LeftX ControllerAxis = iota
+	LeftY
+	RightX
+	RightY
+)
+
+type ControlMapping struct {
+	CommentStr string
+	MidiChannel uint8
+	MidiController uint8
+	Axis ControllerAxis
+	IsSigned bool
+	Deadzone float64
+}
+
+// Is checks if the MIDI message msg triggers this Mapping, without actually triggering it.
+func (m ControlMapping) Is(msg midi.Message) bool {
+	var channel, controller uint8
+
+	if msg.GetControlChange(&channel, &controller, nil) {
+		return (m.MidiChannel == channel && m.MidiController == controller)
+	} else {
+		return false
+	}
+}
+
+// TriggerIfMatch checks if the MIDI message msg triggers this Mapping, and if so,
+// sends the corresponding input to virtGamepad.
+func (m ControlMapping) TriggerIfMatch(msg midi.Message, virtGamepad uinput.Gamepad) error {
+	if m.Is(msg) {
+		var (
+			valueAbsolute uint8
+			valueNormalised float64
+		)
+
+		msg.GetControlChange(nil, nil, &valueAbsolute)
+
+		// value is 0-127, normalise
+		valueNormalised = float64(valueAbsolute) / 127
+		if m.IsSigned {
+			valueNormalised *= 2
+			valueNormalised -= 1
+		}
+
+		if math.Abs(valueNormalised) < m.Deadzone {
+			valueNormalised = 0
+		}
+
+		log.Debug(m.CommentStr, "value", valueNormalised, "deadzone", m.Deadzone)
+
+		switch m.Axis {
+		case LeftX:
+			return virtGamepad.LeftStickMoveX(float32(valueNormalised))
+		case LeftY:
+			return virtGamepad.LeftStickMoveY(float32(valueNormalised))
+		case RightX:
+			return virtGamepad.RightStickMoveX(float32(valueNormalised))
+		case RightY:
+			return virtGamepad.RightStickMoveY(float32(valueNormalised))
+		}
+	}
+
+	return nil
+}
+
+// Comment returns the Mappings comment.
+func (m ControlMapping) Comment() string {
+	return m.CommentStr
+}