feat: PDF and document file viewing support

Matthias Nott

3 days ago cda5ac96c4802f7c33f8f0099a8c9c34423dde4a

 lib/services/mqtt_service.dart
..
..
@@ -68,6 +68,13 @@
68
68
   // (Per-session subscriptions removed — single pailot/out topic now)
69
69
   static const int _maxSeenIds = 500;
70
70
 
71
+  // Reconnect backoff
72
+  Timer? _reconnectTimer;
73
+  Timer? _stabilityTimer;
74
+  int _reconnectAttempt = 0;
75
+  static const int _maxReconnectDelay = 30000; // 30s cap
76
+  static const int _stabilityThresholdMs = 10000; // 10s stable = reset backoff
77
+
71
78
   // Callbacks
72
79
   void Function(ConnectionStatus status)? onStatusChanged;
73
80
   void Function(String detail)? onStatusDetail; // "Probing local...", "Scanning network..."
..
..
@@ -120,16 +127,16 @@
120
127
   }
121
128
 
122
129
   /// Fast reconnect to a known host — skips discovery, short timeout.
123
-  Future<void> _fastReconnect(String host) async {
130
+  /// Returns true if connected, false if failed.
131
+  Future<bool> _fastReconnect(String host) async {
124
132
     _mqttLog('MQTT: fast reconnect to $host');
125
133
     final clientId = await _getClientId();
126
134
     if (await _tryConnect(host, clientId, timeout: 2000)) {
127
135
       connectedHost = host;
128
-      return;
136
+      return true;
129
137
     }
130
-    // Fast path failed — fall back to full connect
131
-    _mqttLog('MQTT: fast reconnect failed, full connect...');
132
-    connect();
138
+    _mqttLog('MQTT: fast reconnect failed');
139
+    return false;
133
140
   }
134
141
 
135
142
   /// Connect to the MQTT broker.
..
..
@@ -440,7 +447,9 @@
440
447
       );
441
448
       _mqttLog('MQTT: connect result=${result?.state}');
442
449
       if (result?.state == MqttConnectionState.connected) {
443
-        client.autoReconnect = true;
450
+        // Don't use autoReconnect — it has no backoff and causes tight reconnect loops.
451
+        // We handle reconnection manually in _onDisconnected with exponential backoff.
452
+        _reconnectAttempt = 0;
444
453
         return true;
445
454
       }
446
455
       _client = null;
..
..
@@ -454,6 +463,17 @@
454
463
 
455
464
   void _onConnected() {
456
465
     _mqttLog('MQTT: _onConnected fired');
466
+    _reconnectTimer?.cancel();
467
+    // Don't reset _reconnectAttempt here — only after the connection has been
468
+    // STABLE for 10+ seconds. This prevents flap loops where each brief connect
469
+    // resets the backoff and we hammer the server every 5s forever.
470
+    _stabilityTimer?.cancel();
471
+    _stabilityTimer = Timer(const Duration(milliseconds: _stabilityThresholdMs), () {
472
+      if (_status == ConnectionStatus.connected) {
473
+        _mqttLog('MQTT: connection stable for ${_stabilityThresholdMs}ms — resetting backoff');
474
+        _reconnectAttempt = 0;
475
+      }
476
+    });
457
477
     _setStatus(ConnectionStatus.connected);
458
478
     _subscribe();
459
479
     _listenMessages();
..
..
@@ -461,6 +481,7 @@
461
481
   }
462
482
 
463
483
   void _onDisconnected() {
484
+    _stabilityTimer?.cancel();
464
485
     _updatesSub?.cancel();
465
486
     _updatesSub = null;
466
487
 
..
..
@@ -470,15 +491,41 @@
470
491
     } else {
471
492
       _setStatus(ConnectionStatus.reconnecting);
472
493
       onReconnecting?.call();
494
+      _scheduleReconnect();
473
495
     }
474
496
   }
475
497
 
498
+  void _scheduleReconnect() {
499
+    _reconnectTimer?.cancel();
500
+    // Exponential backoff: 1s, 2s, 4s, 8s, 16s, 30s cap
501
+    final delayMs = (1000 * (1 << _reconnectAttempt)).clamp(1000, _maxReconnectDelay);
502
+    _reconnectAttempt++;
503
+    _mqttLog('MQTT: scheduling reconnect in ${delayMs}ms (attempt $_reconnectAttempt)');
504
+    _reconnectTimer = Timer(Duration(milliseconds: delayMs), () async {
505
+      if (_intentionalClose || _status == ConnectionStatus.connected) return;
506
+      final host = connectedHost ?? _lastDiscoveredHost;
507
+      if (host != null) {
508
+        _mqttLog('MQTT: reconnect attempt $_reconnectAttempt to $host');
509
+        final ok = await _fastReconnect(host);
510
+        if (!ok && !_intentionalClose) {
511
+          _scheduleReconnect(); // Try again with increased backoff
512
+        }
513
+      } else {
514
+        _mqttLog('MQTT: no known host, running full connect');
515
+        await connect();
516
+      }
517
+    });
518
+  }
519
+
476
520
   void _onAutoReconnect() {
521
+    // Unused — autoReconnect is disabled, but keep callback for safety
477
522
     _setStatus(ConnectionStatus.reconnecting);
478
523
     onReconnecting?.call();
479
524
   }
480
525
 
481
526
   void _onAutoReconnected() {
527
+    // Unused — autoReconnect is disabled, but keep callback for safety
528
+    _reconnectAttempt = 0;
482
529
     _setStatus(ConnectionStatus.connected);
483
530
     _subscribe();
484
531
     _listenMessages();
..
..
@@ -764,6 +811,11 @@
764
811
   /// Disconnect intentionally.
765
812
   void disconnect() {
766
813
     _intentionalClose = true;
814
+    _reconnectTimer?.cancel();
815
+    _reconnectTimer = null;
816
+    _stabilityTimer?.cancel();
817
+    _stabilityTimer = null;
818
+    _reconnectAttempt = 0;
767
819
     _updatesSub?.cancel();
768
820
     _updatesSub = null;
769
821
     _connectivitySub?.cancel();
..
..
@@ -799,8 +851,12 @@
799
851
       case AppLifecycleState.resumed:
800
852
         if (_intentionalClose) break;
801
853
         _mqttLog('MQTT: app resumed');
802
-        // Let autoReconnect handle dead connections (keepalive timeout).
803
-        // Just trigger catch_up to fetch missed messages and rebuild UI.
854
+        // If disconnected, trigger immediate reconnect (reset backoff).
855
+        if (_status != ConnectionStatus.connected) {
856
+          _reconnectAttempt = 0;
857
+          _scheduleReconnect();
858
+        }
859
+        // Trigger catch_up to fetch missed messages and rebuild UI.
804
860
         onResume?.call();
805
861
       case AppLifecycleState.paused:
806
862
         break;