Send DC info for syncState (#88)

* dc private methods

* impl

* pub

* id

* fix test

lib/src/core/engine.dart

@@ -529,6 +529,7 @@ class Engine extends Disposable with EventsEmittable<EngineEvent> {
       answer: answer,
       subscription: subscription,
       publishTracks: publishTracks,
+      dataChannelInfo: dataChannelInfo(),
     );
   }
 
@@ -643,7 +644,16 @@ class Engine extends Disposable with EventsEmittable<EngineEvent> {
             )));
 }
 
-extension EngineInternalMethods on Engine {
+extension EnginePrivateMethods on Engine {
+  // publisher data channel for the reliability
+  rtc.RTCDataChannel? _publisherDataChannel(Reliability reliability) =>
+      reliability == Reliability.reliable ? _reliableDCPub : _lossyDCPub;
+
+  // state of the publisher data channel
+  rtc.RTCDataChannelState _publisherDataChannelState(Reliability reliability) =>
+      _publisherDataChannel(reliability)?.state ??
+      rtc.RTCDataChannelState.RTCDataChannelClosed;
+
   void _updateConnectionState(ConnectionState newValue) {
     if (_connectionState == newValue) return;
 
@@ -664,13 +674,10 @@ extension EngineInternalMethods on Engine {
   }
 }
 
-extension EnginePrivateMethods on Engine {
-  // publisher data channel for the reliability
-  rtc.RTCDataChannel? _publisherDataChannel(Reliability reliability) =>
-      reliability == Reliability.reliable ? _reliableDCPub : _lossyDCPub;
-
-  // state of the publisher data channel
-  rtc.RTCDataChannelState _publisherDataChannelState(Reliability reliability) =>
-      _publisherDataChannel(reliability)?.state ??
-      rtc.RTCDataChannelState.RTCDataChannelClosed;
+extension EngineInternalMethods on Engine {
+  @internal
+  List<lk_rtc.DataChannelInfo> dataChannelInfo() => [
+        _reliableDCPub,
+        _lossyDCPub
+      ].whereNotNull().map((e) => e.toLKInfoType()).toList();
 }

lib/src/core/signal_client.dart

@@ -352,12 +352,14 @@ extension SignalClientRequests on SignalClient {
     required lk_rtc.SessionDescription? answer,
     required lk_rtc.UpdateSubscription subscription,
     required Iterable<lk_rtc.TrackPublishedResponse>? publishTracks,
+    required Iterable<lk_rtc.DataChannelInfo>? dataChannelInfo,
   }) =>
       _sendRequest(lk_rtc.SignalRequest(
         syncState: lk_rtc.SyncState(
           answer: answer,
           subscription: subscription,
           publishTracks: publishTracks,
+          dataChannels: dataChannelInfo,
         ),
       ));
 

lib/src/extensions.dart

@@ -53,6 +53,13 @@ extension ReliabilityExt on Reliability {
       }[this]!;
 }
 
+extension RTCDataChannelExt on rtc.RTCDataChannel {
+  lk_rtc.DataChannelInfo toLKInfoType() => lk_rtc.DataChannelInfo(
+        id: id,
+        label: label,
+      );
+}
+
 extension RTCIceCandidateExt on rtc.RTCIceCandidate {
   static rtc.RTCIceCandidate fromJson(String jsonString) {
     final map = json.decode(jsonString) as Map<String, dynamic>;