From 54a8164dd38b845f9c5808125a98e02c59712f04 Mon Sep 17 00:00:00 2001
From: Joel Wetzell <git@jwetzell.com>
Date: Sat, 13 Dec 2025 08:51:29 -0600
Subject: [PATCH] add midi message unpack to pul values out of common MIDI
 types

---
 internal/processor/midi-message-unpack.go | 90 +++++++++++++++++++++++
 1 file changed, 90 insertions(+)
 create mode 100644 internal/processor/midi-message-unpack.go

diff --git a/internal/processor/midi-message-unpack.go b/internal/processor/midi-message-unpack.go
new file mode 100644
index 0000000..5933f9e
--- /dev/null
+++ b/internal/processor/midi-message-unpack.go
@@ -0,0 +1,90 @@
+//go:build cgo
+
+package processor
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/jwetzell/showbridge-go/internal/config"
+	"gitlab.com/gomidi/midi/v2"
+)
+
+type MIDIMessageUnpack struct {
+	config config.ProcessorConfig
+}
+
+type MIDINoteOn struct {
+	Channel  uint8
+	Note     uint8
+	Velocity uint8
+}
+
+type MIDINoteOff struct {
+	Channel  uint8
+	Note     uint8
+	Velocity uint8
+}
+
+type MIDIControlChange struct {
+	Channel uint8
+	Control uint8
+	Value   uint8
+}
+
+type MIDIProgramChange struct {
+	Channel uint8
+	Program uint8
+}
+
+type MIDIPitchBend struct {
+	Channel  uint8
+	Relative int16
+	Absolute uint16
+}
+
+func (mmu *MIDIMessageUnpack) Process(ctx context.Context, payload any) (any, error) {
+	payloadMidi, ok := payload.(midi.Message)
+
+	if !ok {
+		return nil, fmt.Errorf("midi.message.unpack processor only accepts a midi.Message")
+	}
+
+	switch payloadMidi.Type() {
+	case midi.NoteOnMsg:
+		noteOnMsg := MIDINoteOn{}
+		payloadMidi.GetNoteOn(&noteOnMsg.Channel, &noteOnMsg.Note, &noteOnMsg.Velocity)
+		return noteOnMsg, nil
+	case midi.NoteOffMsg:
+		noteOffMsg := MIDINoteOff{}
+		payloadMidi.GetNoteOff(&noteOffMsg.Channel, &noteOffMsg.Note, &noteOffMsg.Velocity)
+		return noteOffMsg, nil
+	case midi.ControlChangeMsg:
+		controlChangeMsg := MIDIControlChange{}
+		payloadMidi.GetControlChange(&controlChangeMsg.Channel, &controlChangeMsg.Control, &controlChangeMsg.Value)
+		return controlChangeMsg, nil
+	case midi.ProgramChangeMsg:
+		programChangeMsg := MIDIProgramChange{}
+		payloadMidi.GetProgramChange(&programChangeMsg.Channel, &programChangeMsg.Program)
+		return programChangeMsg, nil
+	case midi.PitchBendMsg:
+		pitchBendMsg := MIDIPitchBend{}
+		payloadMidi.GetPitchBend(&pitchBendMsg.Channel, &pitchBendMsg.Relative, &pitchBendMsg.Absolute)
+		return pitchBendMsg, nil
+	default:
+		return nil, fmt.Errorf("midi.message.unpack message type not supported %v", payloadMidi.Type())
+	}
+}
+
+func (mmu *MIDIMessageUnpack) Type() string {
+	return mmu.config.Type
+}
+
+func init() {
+	RegisterProcessor(ProcessorRegistration{
+		Type: "midi.message.unpack",
+		New: func(config config.ProcessorConfig) (Processor, error) {
+			return &MIDIMessageUnpack{config: config}, nil
+		},
+	})
+}