Display MQTT connection status

The user otherwise cannot trust the state of the contacts because the
app could just be disconnected from the broker.

1 files changed, 11 insertions, 1 deletions

diff --git a/lib/data.dart b/lib/data.dart
index 08f8881..f5a24e8 100644
--- a/lib/data.dart
+++ b/lib/data.dart
@@ -10,8 +10,9 @@ const String topicPrefix = 'sia';
 
 class AppState with ChangeNotifier {
   Map<String, bool> contacts = <String, bool>{};
-
   late final MqttServerClient _client;
+  bool _brokerConnected = false;
+  bool get brokerConnected => _brokerConnected;
 
   AppState() {
     _initMqtt();
@@ -31,9 +32,11 @@ class AppState with ChangeNotifier {
 
     _client.port = brokerPort;
     _client.keepAlivePeriod = 2;
+    _client.disconnectOnNoResponsePeriod = 1;
     _client.logging(on: false);
 
     _client.onConnected = _onConnected;
+    _client.onDisconnected = _onDisconnected;
 
     try {
       await _client.connect();
@@ -47,6 +50,13 @@ class AppState with ChangeNotifier {
 
   void _onConnected() {
     _client.subscribe('$topicPrefix/contact/+/state', MqttQos.exactlyOnce);
+    _brokerConnected = true;
+    notifyListeners();
+  }
+
+  void _onDisconnected() {
+    _brokerConnected = false;
+    notifyListeners();
   }
 
   void _onMessage(List<MqttReceivedMessage<MqttMessage>> messages) {