Add connection health indicator

backend/src/DataSource/DataSourceState.ts

@@ -25,16 +25,17 @@ export class DataSourceStateMachine {
 
   public setError(error: Error) {
     this.state = {
+      ...this.state,
       error: error.message,
-      connected: false,
-      connecting: false,
+      // connected: false,
+      // connecting: false,
     }
     this.onUpdate.dispatch(this.state)
   }
 
   public setConnecting() {
     this.state = {
-      error: undefined,
+      ...this.state,
       connected: false,
       connecting: true,
     }

backend/src/DataSource/MqttSource.ts

@@ -55,6 +55,10 @@ export class MqttSource implements DataSource<MqttOptions> {
       this.stateMachine.setConnected(false)
     })
 
+    client.on('end', () => {
+      this.stateMachine.setConnected(false)
+    })
+
     client.on('reconnect', () => {
       this.stateMachine.setConnecting()
     })

backend/src/index.ts

@@ -61,6 +61,7 @@ export class ConnectionManager {
     if (connection) {
       connection.disconnect()
       delete this.connections[hash]
+      connection.stateMachine.onUpdate.removeAllListeners()
     }
   }