1 files changed, 78 insertions, 11 deletions

diff --git a/pkg/mixer/mixer.go b/pkg/mixer/mixer.go
index ee25207..c774342 100644
--- a/pkg/mixer/mixer.go
+++ b/pkg/mixer/mixer.go
@@ -23,8 +23,9 @@
 package mixer
 
 import (
+	"container/list"
 	"errors"
-	"log"
+	"fmt"
 	"strings"
 
 	"github.com/scgolang/midi"
@@ -33,12 +34,41 @@ import (
 type Channel uint8
 type FaderLevel uint8
 
+type EventType int
+
+const (
+	EventFaderChange = iota
+	EventMute
+)
+
+func (et EventType) String() string {
+	switch et {
+	case EventFaderChange:
+		return "fader-change"
+	case EventMute:
+		return "mute"
+	default:
+		return "unknown"
+	}
+}
+
+type Event struct {
+	Channel Channel
+	Type    EventType
+	Value   uint8
+}
+
+func (e Event) String() string {
+	return fmt.Sprintf("Event(%s) for channel 0x%02X, value=%d", e.Type, e.Channel, e.Value)
+}
+
 type Mixer struct {
-	DevIn  *midi.Device
-	DevOut *midi.Device
+	DevIn       *midi.Device
+	DevOut      *midi.Device
+	subscribers map[Channel]*list.List
 }
 
-// TODO: make this confgurable
+// TODO: make this configurable
 const (
 	CC_MUTE  = byte(0xB1)
 	CC_FADER = byte(0xB0)
@@ -66,31 +96,58 @@ func NewMixer(c Config) (*Mixer, error) {
 		return nil, err
 	}
 
+	// TODO: add support for DevIn == DevOut
 	m := &Mixer{}
 	if m.DevIn, err = openDevice(devices, c.DevIn); err != nil {
 		return nil, err
 	}
+	m.DevIn.QueueSize = 100
 	if m.DevOut, err = openDevice(devices, c.DevOut); err != nil {
 		return nil, err
 	}
 
-	m.DevIn.QueueSize = 100
-	m.DevOut.QueueSize = 100
+	m.subscribers = make(map[Channel]*list.List)
 	return m, nil
 }
 
+func (m *Mixer) sendEvent(ev Event) {
+	subs, exists := m.subscribers[ev.Channel]
+	if exists && subs != nil {
+		var next *list.Element
+		for sub := subs.Front(); sub != nil; sub = next {
+			next = sub.Next()
+
+			ch, ok := (sub.Value).(chan<- Event)
+			if !ok {
+				panic(fmt.Sprintf("mixer: subscriber list element value has wrong type: %T", sub.Value))
+			}
+
+			select {
+			case ch <- ev:
+			default:
+				// subscriber is not respoding...
+				subs.Remove(sub)
+			}
+		}
+	}
+}
+
 func (m *Mixer) handleMidiPacket(p midi.Packet) {
+	ev := Event{}
+	ev.Channel = Channel(p.Data[1])
 	switch p.Data[0] {
 	case CC_FADER:
-		log.Printf("mixer: fader movement on channel 0x%02X, level is now: 0x%02X", p.Data[1], p.Data[2])
+		ev.Type = EventFaderChange
+		ev.Value = p.Data[2]
 	case CC_MUTE:
-		newState := "unmuted"
+		ev.Type = EventMute
 		if p.Data[2] > 0 {
-			newState = "muted"
+			ev.Value = 1
 		}
-		log.Printf("mixer: channel 0x%02X is now %s", p.Data[1], newState)
+	default:
+		return
 	}
-	// TODO: send new state to subscribers
+	m.sendEvent(ev)
 }
 
 func (m *Mixer) Init() error {
@@ -149,3 +206,13 @@ func (m *Mixer) SetLevel(ch Channel, level FaderLevel) error {
 	}
 	return nil
 }
+
+func (m *Mixer) Subscribe(ch Channel, out chan<- Event) {
+	subs, exists := m.subscribers[ch]
+	if !exists {
+		subs = list.New()
+		m.subscribers[ch] = subs
+	}
+
+	subs.PushBack(out)
+}