Implement mqtt last will message. #267

lib/mqtt.js

@@ -12,7 +12,14 @@ class MQTT {
         const mqttSettings = settings.get().mqtt;
         logger.info(`Connecting to MQTT server at ${mqttSettings.server}`);
 
-        const options = {};
+        const options = {
+            will: {
+                topic: this.prefixTopic('bridge/state'),
+                payload: 'offline',
+                retain: true,
+            },
+        };
+
         if (mqttSettings.user && mqttSettings.password) {
             options.username = mqttSettings.user;
             options.password = mqttSettings.password;
@@ -68,8 +75,7 @@ class MQTT {
     }
 
     publish(topic, payload, options, callback, baseTopic) {
-        baseTopic = baseTopic ? baseTopic : settings.get().mqtt.base_topic;
-        topic = `${baseTopic}/${topic}`;
+        topic = this.prefixTopic(topic, baseTopic);
 
         if (!this.client || this.client.reconnecting) {
             logger.error(`Not connected to MQTT server!`);
@@ -81,6 +87,11 @@ class MQTT {
         this.client.publish(topic, payload, options, callback);
     }
 
+    prefixTopic(topic, baseTopic) {
+        baseTopic = baseTopic ? baseTopic : settings.get().mqtt.base_topic;
+        return `${baseTopic}/${topic}`;
+    }
+
     log(type, message) {
         const payload = {type: type, message: message};
         this.publish('bridge/log', JSON.stringify(payload), {retain: false});