Separate MQTT logic

This reduces the coupling between the MQTT-related code and everything
else to a single `tx` channel of type `MQTTMessage`.

This improves the code quality significantly.

1 files changed, 51 insertions, 0 deletions

diff --git a/mqtt.go b/mqtt.go
new file mode 100644
index 0000000..2fd4d13
--- /dev/null
+++ b/mqtt.go
@@ -0,0 +1,51 @@
+package main
+
+import (
+	"log"
+	"time"
+
+	mqtt "github.com/eclipse/paho.mqtt.golang"
+)
+
+const (
+	BROKER                     = `tcp://127.0.0.1:1883`
+	CLIENT_ID                  = `siaserver`
+	TOPIC_PREFIX               = `sia`
+	QOS                        = byte(1)
+	RETAINED                   = true
+	MQTT_CONNECT_TIMEOUT       = 1 * time.Second
+	MQTT_DISCONNECT_TIMEOUT_US = 500
+	MQTT_RECONNECT_PERIOD      = 2 * time.Second
+)
+
+type MQTTMessage struct {
+	Topic   string
+	Payload []byte
+}
+
+func MQTTRun(tx chan MQTTMessage) {
+	opts := mqtt.NewClientOptions()
+	opts.AddBroker(BROKER)
+	opts.SetClientID(CLIENT_ID)
+	opts.SetCleanSession(true)
+	opts.SetOnConnectHandler(MQTTOnConnectHandler)
+
+	client := mqtt.NewClient(opts)
+
+	token := client.Connect()
+
+	success := token.WaitTimeout(MQTT_CONNECT_TIMEOUT)
+	if !success {
+		log.Printf("Timed out after %v.", MQTT_CONNECT_TIMEOUT)
+		return
+	}
+	defer client.Disconnect(MQTT_DISCONNECT_TIMEOUT_US)
+
+	for message := range tx {
+		client.Publish(message.Topic, QOS, RETAINED, message.Payload)
+	}
+}
+
+func MQTTOnConnectHandler(c mqtt.Client) {
+	log.Printf("Connected to MQTT broker (%s)", BROKER)
+}