1 files changed, 83 insertions, 25 deletions

diff --git a/lib/data.dart b/lib/data.dart
index 2583d1a..365f5bc 100644
--- a/lib/data.dart
+++ b/lib/data.dart
@@ -1,23 +1,82 @@
-import 'dart:async';
-
 import 'package:flutter/foundation.dart';
 import 'package:mqtt_client/mqtt_client.dart';
 import 'package:mqtt_client/mqtt_server_client.dart';
 
-const String brokerHostname = 'sia.xengineering.eu';
 const int brokerPort = 1883;
 const String topicPrefix = 'sia';
 
+enum MachineState {
+  init,          // user does not want connection MQTT not connected
+  disconnected,  // user wants connection but MQTT not (yet) connected
+  unreachable,   // connected to MQTT broker but Sia server not reachable
+  reachable,     // connected to MQTT and Sia server reachable
+}
+
+enum MachineEvent {
+  connect,       // user wants to connect
+  disconnect,    // user does not want an connection anymore
+  connected,     // connection to MQTT broker established
+  disconnected,  // connection to MQTT broker lost
+  reachable,     // Sia server is reachable via MQTT
+  unreachable,   // Sia server not reachable via MQTT
+}
+
 class AppState with ChangeNotifier {
+  static const Map<MachineState, Map<MachineEvent, MachineState>> machine = <MachineState, Map<MachineEvent, MachineState>> {
+    MachineState.init: <MachineEvent, MachineState> {
+      MachineEvent.connect: MachineState.disconnected,
+    },
+    MachineState.disconnected: <MachineEvent, MachineState> {
+      MachineEvent.disconnect: MachineState.init,
+      MachineEvent.connected: MachineState.unreachable,
+    },
+    MachineState.unreachable: <MachineEvent, MachineState> {
+      MachineEvent.disconnect: MachineState.init,
+      MachineEvent.disconnected: MachineState.disconnected,
+      MachineEvent.reachable: MachineState.reachable,
+    },
+    MachineState.reachable: <MachineEvent, MachineState> {
+      MachineEvent.disconnect: MachineState.init,
+      MachineEvent.disconnected: MachineState.disconnected,
+      MachineEvent.unreachable: MachineState.unreachable,
+    },
+  };
+  MachineState state = MachineState.init;
+
   Map<String, bool> contacts = <String, bool>{};
-  late final MqttServerClient _client;
-  bool _brokerConnected = false;
-  bool get brokerConnected => _brokerConnected;
-  bool _serverConnected = false;
-  bool get serverConnected => _serverConnected;
+  late MqttServerClient _client;
+
+  String fqdn = '';
+
+  AppState();
 
-  AppState() {
-    _initMqtt();
+  void process(MachineEvent event) {
+    MachineState lastState = state;
+
+    Map<MachineEvent, MachineState>? transitions = machine[lastState];
+    if (transitions == null) {
+      return;
+    }
+
+    MachineState? nextState = transitions[event];
+    if (nextState == null) {
+      return;
+    }
+
+    if (nextState == lastState) {
+      return;
+    }
+
+    if (lastState == MachineState.init) {
+      _initMqtt();
+    }
+
+    if (nextState == MachineState.init) {
+      _deinitMqtt();
+    }
+
+    state = nextState;
+    notifyListeners();
   }
 
   @override
@@ -26,9 +85,9 @@ class AppState with ChangeNotifier {
     super.dispose();
   }
 
-  Future<void> _initMqtt() async {
+  void _initMqtt() {
     _client = MqttServerClient(
-      brokerHostname,
+      fqdn,
       'sia_app_${DateTime.now().millisecondsSinceEpoch}',
     );
 
@@ -44,7 +103,7 @@ class AppState with ChangeNotifier {
     _client.onAutoReconnected = _onAutoReconnected;
 
     try {
-      await _client.connect();
+      _client.connect();
     } catch (e) {
       _client.disconnect();
       return;
@@ -53,26 +112,27 @@ class AppState with ChangeNotifier {
     _client.updates?.listen(_onMessage);
   }
 
+  void _deinitMqtt() {
+    _client.disconnect();
+  }
+
   void _onConnected() {
     _client.subscribe('$topicPrefix/contact/+/state', MqttQos.exactlyOnce);
     _client.subscribe('$topicPrefix/server/health', MqttQos.exactlyOnce);
-    _brokerConnected = true;
-    notifyListeners();
+
+    process(MachineEvent.connected);
   }
 
   void _onDisconnected() {
-    _brokerConnected = false;
-    notifyListeners();
+    process(MachineEvent.disconnected);
   }
 
   void _onAutoReconnect() {
-    _brokerConnected = false;
-    notifyListeners();
+    process(MachineEvent.disconnected);
   }
 
   void _onAutoReconnected() {
-    _brokerConnected = true;
-    notifyListeners();
+    process(MachineEvent.connected);
   }
 
   void _onMessage(List<MqttReceivedMessage<MqttMessage>> messages) {
@@ -86,13 +146,11 @@ class AppState with ChangeNotifier {
 
       if (topic == '$topicPrefix/server/health') {
         if (payload == 'good') {
-          _serverConnected = true;
-          notifyListeners();
+          process(MachineEvent.reachable);
         }
 
         if (payload == 'bad') {
-          _serverConnected = false;
-          notifyListeners();
+          process(MachineEvent.unreachable);
         }
       }