Switch completely to connection state machine

This makes use of the state machine in the UI and implements all states
and transitions planned so far.

2 files changed, 39 insertions, 27 deletions

diff --git a/lib/data.dart b/lib/data.dart
index 415e61e..eaf301a 100644
--- a/lib/data.dart
+++ b/lib/data.dart
@@ -9,11 +9,17 @@ 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 {
@@ -23,16 +29,23 @@ class AppState with ChangeNotifier {
     },
     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 MqttServerClient _client;
-  bool _brokerConnected = false;
-  bool get brokerConnected => _brokerConnected;
-  bool _serverConnected = false;
-  bool get serverConnected => _serverConnected;
 
   AppState();
 
@@ -105,23 +118,20 @@ class AppState with ChangeNotifier {
   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) {
@@ -135,13 +145,11 @@ 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);
         }
       }
 
diff --git a/lib/ui.dart b/lib/ui.dart
index e14895b..7a97f32 100644
--- a/lib/ui.dart
+++ b/lib/ui.dart
@@ -98,18 +98,22 @@ class ConnectionStatus extends StatelessWidget {
     return  SafeArea(
       child: Consumer<AppState>(
         builder: (BuildContext context, AppState state, Widget? child) {
-          Icon icon;
-          Text text;
+          Icon icon = const Icon(Icons.cloud_off, color: Colors.grey);
+          Text text = const Text('Disconnected');
 
-          if (state.brokerConnected && state.serverConnected) {
-            icon = const Icon(Icons.cloud, color: Colors.green);
-            text = const Text('Connected');
-          } else if (state.brokerConnected && !state.serverConnected) {
-            icon = const Icon(Icons.cloud_off, color: Colors.orange);
-            text = const Text('Connection issue');
-          } else {
-            icon = const Icon(Icons.cloud_off, color: Colors.red);
-            text = const Text('Disconnected');
+          switch (state.state) {
+            case MachineState.init:
+              icon = const Icon(Icons.cloud_off, color: Colors.grey);
+              text = const Text('Off');
+            case MachineState.disconnected:
+              icon = const Icon(Icons.cloud_off, color: Colors.red);
+              text = const Text('Disconnected');
+            case MachineState.unreachable:
+              icon = const Icon(Icons.cloud_off, color: Colors.orange);
+              text = const Text('Unreachable');
+            case MachineState.reachable:
+              icon = const Icon(Icons.cloud, color: Colors.green);
+              text = const Text('Connected');
           }
 
           MachineEvent event = MachineEvent.disconnect;