feat(bridge): MQTT bridge with Home Assistant auto-discovery

pkg/bridge/types.go

@@ -0,0 +1,94 @@
+package bridge
+
+import (
+	"errors"
+	"log/slog"
+	"sync/atomic"
+	"time"
+
+	mqtt "github.com/eclipse/paho.mqtt.golang"
+
+	"gitea.berezovskyi.dev/oleksandr/ezcoo-usb-control/pkg/ezcoo"
+)
+
+var ErrShutdown = errors.New("bridge: shutdown requested")
+
+type Device interface {
+	SetOutput(out, in int)
+	GetStatus() ezcoo.State
+}
+
+type Bridge struct {
+	cfg       Config
+	client    mqtt.Client
+	dev       Device
+	done      <-chan struct{}
+	available atomic.Bool
+}
+
+func New(cfg Config, dev Device, done <-chan struct{}) *Bridge {
+	b := &Bridge{cfg: cfg, dev: dev, done: done}
+	opts := mqtt.NewClientOptions().
+		AddBroker(cfg.Broker).
+		SetClientID(cfg.ClientID).
+		SetUsername(cfg.Username).
+		SetPassword(cfg.Password).
+		SetAutoReconnect(true).
+		SetWill(b.availTopic(), "offline", 1, true).
+		SetOnConnectHandler(func(c mqtt.Client) {
+			slog.Info("MQTT connected")
+			b.onConnect(c)
+		}).
+		SetConnectionLostHandler(func(_ mqtt.Client, err error) {
+			slog.Warn("MQTT connection lost", "err", err)
+		})
+	b.client = mqtt.NewClient(opts)
+	return b
+}
+
+func (b *Bridge) OnState(s ezcoo.State) {
+	if !b.client.IsConnected() {
+		return
+	}
+	for out := 1; out <= numOutputs; out++ {
+		in := s[out-1]
+		if in >= 1 && in <= numInputs {
+			b.client.Publish(b.stateTopic(out), 1, true, inputLabel(in))
+			slog.Debug("state update", "output", out, "input", in)
+		}
+	}
+}
+
+func (b *Bridge) SetAvailable(online bool) {
+	b.available.Store(online)
+	if b.client.IsConnected() {
+		b.client.Publish(b.availTopic(), 1, true, b.availPayload())
+		slog.Info("availability", "online", online)
+	}
+}
+
+func (b *Bridge) Connect() error {
+	for {
+		tok := b.client.Connect()
+		if tok.WaitTimeout(5 * time.Second) {
+			if tok.Error() == nil {
+				return nil
+			}
+			slog.Warn("MQTT connect failed, retrying in 5s", "err", tok.Error())
+		} else {
+			slog.Warn("MQTT connect timed out, retrying in 5s")
+		}
+		select {
+		case <-b.done:
+			return ErrShutdown
+		case <-time.After(5 * time.Second):
+		}
+	}
+}
+
+func (b *Bridge) Run() {
+	<-b.done
+	tok := b.client.Publish(b.availTopic(), 1, true, "offline")
+	tok.WaitTimeout(2 * time.Second)
+	b.client.Disconnect(500)
+}