Add region management

This adds region management: the user can manage a list of available regions
and for each channel pick a region from that list to apply to messages.

Region discovery from nearby repeaters will be done in a separate PR.

This is a part of the work needed for #120.

lib/connector/meshcore_connector.dart

@@ -3,6 +3,7 @@ import 'dart:convert';
 import 'dart:math' as math;
 
 import 'package:crypto/crypto.dart' as crypto;
+import 'package:meshcore_open/storage/region_store.dart';
 import 'package:pointycastle/export.dart';
 import 'package:flutter/foundation.dart';
 import 'package:flutter_blue_plus/flutter_blue_plus.dart';
@@ -34,6 +35,7 @@ import 'meshcore_connector_tcp.dart';
 import '../storage/channel_message_store.dart';
 import '../storage/channel_order_store.dart';
 import '../storage/channel_settings_store.dart';
+import '../storage/channel_region_store.dart';
 import '../storage/channel_store.dart';
 import '../storage/contact_discovery_store.dart';
 import '../storage/contact_settings_store.dart';
@@ -276,6 +278,7 @@ class MeshCoreConnector extends ChangeNotifier {
   final MessageStore _messageStore = MessageStore();
   final ChannelOrderStore _channelOrderStore = ChannelOrderStore();
   final ChannelSettingsStore _channelSettingsStore = ChannelSettingsStore();
+  final ChannelRegionStore _channelRegionStore = ChannelRegionStore();
   final ContactSettingsStore _contactSettingsStore = ContactSettingsStore();
   final ContactStore _contactStore = ContactStore();
   final ContactDiscoveryStore _discoveryContactStore = ContactDiscoveryStore();
@@ -283,6 +286,7 @@ class MeshCoreConnector extends ChangeNotifier {
   final UnreadStore _unreadStore = UnreadStore();
   List<Channel> _cachedChannels = [];
   final Map<int, bool> _channelSmazEnabled = {};
+  final Map<int, Region> _channelRegions = {};
   bool _lastSentWasCliCommand =
       false; // Track if last sent message was a CLI command
   final Map<String, bool> _contactSmazEnabled = {};
@@ -603,6 +607,14 @@ class MeshCoreConnector extends ChangeNotifier {
     return _contactSmazEnabled[contactKeyHex] ?? false;
   }
 
+  bool hasChannelRegion(int channelIndex) {
+    return _channelRegions[channelIndex] != '';
+  }
+
+  Region getChannelRegion(int channelIndex) {
+    return _channelRegions[channelIndex] ?? '';
+  }
+
   void ensureContactSmazSettingLoaded(String contactKeyHex) {
     _ensureContactSmazSettingLoaded(contactKeyHex);
   }
@@ -692,6 +704,14 @@ class MeshCoreConnector extends ChangeNotifier {
     notifyListeners();
   }
 
+  Future<void> setChannelRegion(int channelIndex, String region) async {
+    _channelRegions[channelIndex] = await _channelRegionStore.saveRegion(
+      channelIndex,
+      region,
+    );
+    notifyListeners();
+  }
+
   Future<void> _loadChannelOrder() async {
     _channelOrder = await _channelOrderStore.loadChannelOrder();
     _applyChannelOrder();
@@ -840,9 +860,11 @@ class MeshCoreConnector extends ChangeNotifier {
 
   Future<void> loadChannelSettings({int? maxChannels}) async {
     _channelSmazEnabled.clear();
+    _channelRegions.clear();
     final channelCount = maxChannels ?? _maxChannels;
     for (int i = 0; i < channelCount; i++) {
       _channelSmazEnabled[i] = await _channelSettingsStore.loadSmazEnabled(i);
+      _channelRegions[i] = await _channelRegionStore.loadRegion(i);
     }
   }
 
@@ -2973,12 +2995,19 @@ class MeshCoreConnector extends ChangeNotifier {
       // Send the reaction to the device (don't add as a visible message)
       final reactionQueueId = _nextReactionSendQueueId();
       _pendingChannelSentQueue.add(reactionQueueId);
-      await _waitForRadioQuiet(lastInboundRxTime: _lastChannelMsgRxTime);
-      await sendFrame(
-        buildSendChannelTextMsgFrame(channel.index, text),
-        channelSendQueueId: reactionQueueId,
-        expectsGenericAck: true,
-      );
+      try {
+        await sendFrame(
+          buildSetFloodScopeFrame(getChannelRegion(channel.index)),
+        );
+        await _waitForRadioQuiet(lastInboundRxTime: _lastChannelMsgRxTime);
+        await sendFrame(
+          buildSendChannelTextMsgFrame(channel.index, text),
+          channelSendQueueId: reactionQueueId,
+          expectsGenericAck: true,
+        );
+      } finally {
+        await sendFrame(buildSetFloodScopeFrame(''));
+      }
       return;
     }
 
@@ -3001,12 +3030,17 @@ class MeshCoreConnector extends ChangeNotifier {
         (isChannelSmazEnabled(channel.index) && !isStructuredPayload)
         ? Smaz.encodeIfSmaller(text)
         : text;
-    await _waitForRadioQuiet(lastInboundRxTime: _lastChannelMsgRxTime);
-    await sendFrame(
-      buildSendChannelTextMsgFrame(channel.index, outboundText),
-      channelSendQueueId: message.messageId,
-      expectsGenericAck: true,
-    );
+    try {
+      await sendFrame(buildSetFloodScopeFrame(getChannelRegion(channel.index)));
+      await _waitForRadioQuiet(lastInboundRxTime: _lastChannelMsgRxTime);
+      await sendFrame(
+        buildSendChannelTextMsgFrame(channel.index, outboundText),
+        channelSendQueueId: message.messageId,
+        expectsGenericAck: true,
+      );
+    } finally {
+      await sendFrame(buildSetFloodScopeFrame(''));
+    }
   }
 
   Future<void> removeContact(Contact contact) async {
@@ -3680,6 +3714,7 @@ class MeshCoreConnector extends ChangeNotifier {
     _messageStore.setPublicKeyHex = selfPublicKeyHex;
     _channelOrderStore.setPublicKeyHex = selfPublicKeyHex;
     _channelSettingsStore.setPublicKeyHex = selfPublicKeyHex;
+    _channelRegionStore.setPublicKeyHex = selfPublicKeyHex;
     _contactSettingsStore.setPublicKeyHex = selfPublicKeyHex;
     _contactStore.setPublicKeyHex = selfPublicKeyHex;
     _channelStore.setPublicKeyHex = selfPublicKeyHex;

lib/connector/meshcore_protocol.dart

@@ -1,6 +1,7 @@
 import 'dart:convert';
 import 'dart:typed_data';
 
+import 'package:crypto/crypto.dart' as crypto;
 import 'package:flutter/widgets.dart';
 
 // Buffer Reader - sequential binary data reader with pointer tracking
@@ -211,6 +212,7 @@ const int cmdSendAnonReq = 57;
 const int cmdSetAutoAddConfig = 58;
 const int cmdGetAutoAddConfig = 59;
 const int cmdSetPathHashMode = 61;
+const int cmdSetFloodScope = 54;
 
 // Text message types
 const int txtTypePlain = 0;
@@ -955,3 +957,18 @@ Uint8List buildSendTelemetryReq(Uint8List? pubKey) {
   }
   return writer.toBytes();
 }
+
+//Build CMD_SET_FLOOD_SCOPE
+// Format: [cmd][scope]
+Uint8List buildSetFloodScopeFrame(String region) {
+  if (region == '') {
+    // reset scope
+    return Uint8List.fromList([cmdSetFloodScope, 0]);
+  }
+
+  final name = region.startsWith('#') ? region : '#$region';
+  final hash = crypto.sha256.convert(utf8.encode(name)).bytes;
+  final scope = Uint8List.fromList(hash.sublist(0, 16));
+
+  return Uint8List.fromList([cmdSetFloodScope, 0, ...scope]);
+}