Remove automatic initial connection

The user should provide the fully qualified domain name (FQDN) of the
MQTT broker manually and then press connect to actually connect
including automated re-connects.

As a first step the initial connect is bound to the manual button in the
bottom bar. To reduce the scope the disconnect button is labeled
"(disabled)" to make clear this is not expected to work.

2 files changed, 19 insertions, 16 deletions

diff --git a/lib/data.dart b/lib/data.dart
index 53c3d01..89d8760 100644
--- a/lib/data.dart
+++ b/lib/data.dart
@@ -1,5 +1,3 @@
-import 'dart:async';
-
 import 'package:flutter/foundation.dart';
 import 'package:mqtt_client/mqtt_client.dart';
 import 'package:mqtt_client/mqtt_server_client.dart';
@@ -23,9 +21,6 @@ class AppState with ChangeNotifier {
     MachineState.init: <MachineEvent, MachineState> {
       MachineEvent.connect: MachineState.disconnected,
     },
-    MachineState.disconnected: <MachineEvent, MachineState> {
-      MachineEvent.disconnect: MachineState.init,
-    },
   };
   MachineState state = MachineState.init;
 
@@ -36,22 +31,30 @@ class AppState with ChangeNotifier {
   bool _serverConnected = false;
   bool get serverConnected => _serverConnected;
 
-  AppState() {
-    _initMqtt();
-  }
+  AppState();
 
   void process(MachineEvent event) {
-    Map<MachineEvent, MachineState>? ruleset = machine[state];
-    if (ruleset == null) {
+    MachineState lastState = state;
+
+    Map<MachineEvent, MachineState>? transitions = machine[lastState];
+    if (transitions == null) {
       return;
     }
 
-    MachineState? nextMachineState = ruleset[event];
-    if (nextMachineState == null) {
+    MachineState? nextState = transitions[event];
+    if (nextState == null) {
       return;
     }
 
-    state = nextMachineState;
+    if (nextState == lastState) {
+      return;
+    }
+
+    if (lastState == MachineState.init) {
+      _initMqtt();
+    }
+
+    state = nextState;
     notifyListeners();
   }
 
@@ -61,7 +64,7 @@ class AppState with ChangeNotifier {
     super.dispose();
   }
 
-  Future<void> _initMqtt() async {
+  void _initMqtt() {
     _client = MqttServerClient(
       brokerHostname,
       'sia_app_${DateTime.now().millisecondsSinceEpoch}',
@@ -79,7 +82,7 @@ class AppState with ChangeNotifier {
     _client.onAutoReconnected = _onAutoReconnected;
 
     try {
-      await _client.connect();
+      _client.connect();
     } catch (e) {
       _client.disconnect();
       return;
diff --git a/lib/ui.dart b/lib/ui.dart
index e14895b..1d2ad53 100644
--- a/lib/ui.dart
+++ b/lib/ui.dart
@@ -113,7 +113,7 @@ class ConnectionStatus extends StatelessWidget {
           }
 
           MachineEvent event = MachineEvent.disconnect;
-          String action = 'disconnect';
+          String action = '(disabled)';
           if (state.state == MachineState.init) {
             event = MachineEvent.connect;
             action = 'connect';