feat: MeshCore SAR - Flutter BLE mesh radio companion app

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

lib/providers/helpers/ping_tracker.dart

@@ -0,0 +1,103 @@
+import 'dart:async';
+import 'package:flutter/foundation.dart';
+
+/// Helper class to track pending ping (telemetry) requests
+/// and implement automatic fallback to flooding if no response received
+class PingTracker {
+  // Map of public key hex string to ping request state
+  final Map<String, _PingRequest> _pendingPings = {};
+
+  // Timeout duration for ping responses (seconds)
+  static const int _pingTimeoutSeconds = 5;
+
+  /// Track a new ping request
+  /// Returns a Future that completes when either:
+  /// - A response is received (completes with true)
+  /// - Timeout occurs (completes with false)
+  Future<bool> trackPing({
+    required Uint8List publicKey,
+    required bool wasDirectAttempt,
+  }) {
+    final String keyHex = _publicKeyToHex(publicKey);
+
+    // Cancel any existing pending ping for this contact
+    _pendingPings[keyHex]?.cancel();
+
+    // Create new ping request tracker
+    final completer = Completer<bool>();
+    final timer = Timer(const Duration(seconds: _pingTimeoutSeconds), () {
+      // Timeout occurred - mark as failed
+      _pendingPings.remove(keyHex);
+      if (!completer.isCompleted) {
+        completer.complete(false);
+      }
+    });
+
+    _pendingPings[keyHex] = _PingRequest(
+      publicKey: publicKey,
+      wasDirectAttempt: wasDirectAttempt,
+      timer: timer,
+      completer: completer,
+    );
+
+    return completer.future;
+  }
+
+  /// Mark a ping as successful (response received)
+  /// Should be called when telemetry response arrives
+  void markPingSuccessful(Uint8List publicKey) {
+    final String keyHex = _publicKeyToHex(publicKey);
+    final request = _pendingPings.remove(keyHex);
+
+    if (request != null) {
+      request.cancel();
+      if (!request.completer.isCompleted) {
+        request.completer.complete(true);
+      }
+    }
+  }
+
+  /// Check if there's a pending ping for this contact
+  bool hasPendingPing(Uint8List publicKey) {
+    final String keyHex = _publicKeyToHex(publicKey);
+    return _pendingPings.containsKey(keyHex);
+  }
+
+  /// Get pending ping info (was it a direct attempt?)
+  bool? wasPingDirect(Uint8List publicKey) {
+    final String keyHex = _publicKeyToHex(publicKey);
+    return _pendingPings[keyHex]?.wasDirectAttempt;
+  }
+
+  /// Clear all pending pings (useful on disconnect)
+  void clearAll() {
+    for (final request in _pendingPings.values) {
+      request.cancel();
+    }
+    _pendingPings.clear();
+  }
+
+  /// Convert public key to hex string for map key
+  String _publicKeyToHex(Uint8List publicKey) {
+    return publicKey.map((b) => b.toRadixString(16).padLeft(2, '0')).join('');
+  }
+}
+
+/// Internal class to track a single ping request
+class _PingRequest {
+  final Uint8List publicKey;
+  final bool wasDirectAttempt;
+  final Timer timer;
+  final Completer<bool> completer;
+
+  _PingRequest({
+    required this.publicKey,
+    required this.wasDirectAttempt,
+    required this.timer,
+    required this.completer,
+  });
+
+  void cancel() {
+    timer.cancel();
+  }
+}