fix: Fix getNativeHandle not return correctly

lib/src/impl/agora_rtc_engine_impl.dart

@@ -971,6 +971,46 @@ class RtcEngineImpl extends rtc_engine_ex_binding.RtcEngineExImpl
     }
   }
 
+  @override
+  Future<int> getNativeHandle() async {
+    final apiType =
+        '${isOverrideClassName ? className : 'RtcEngine'}_getNativeHandle';
+
+    final param = createParams({});
+    final callApiResult =
+        await apiCaller.callIrisApi(apiType, jsonEncode(param), buffers: null);
+    if (callApiResult.irisReturnCode < 0) {
+      throw AgoraRtcException(code: callApiResult.irisReturnCode);
+    }
+
+    // In 64-bits system, the native handle ptr value (unsigned long 64) can be 2^64 - 1,
+    // which may greater than the dart int max value (2^63 - 1), so we can not decode
+    // the json with big int native handle ptr value and parse it directly.
+    //
+    // After dart sdk 2.0 support parse hexadecimal in unsigned int64 range.
+    // https://github.com/dart-lang/language/blob/ee1135e0c22391cee17bf3ee262d6a04582d25de/archive/newsletter/20170929.md#semantics
+    //
+    // So we retrive the native handle ptr value from the json string directly, and
+    // parse an int from hexadecimal here.
+    final rawJsonStr = callApiResult.rawData;
+    // TODO(littlegnal): Replace retrive nativeHandleIntPtr logic after EP-253 landed.
+    final rawJsonStrSplit = rawJsonStr.split(',');
+    String resultStr = '';
+    for (final s in rawJsonStrSplit) {
+      if (s.contains('result')) {
+        resultStr = s;
+      }
+    }
+    final nativeHandleIntPtr =
+        resultStr.substring(resultStr.indexOf(':') + 1, resultStr.length - 1);
+
+    BigInt nativeHandleBI = BigInt.parse(nativeHandleIntPtr);
+    int nativeHandleBIHexInt =
+        int.parse('0x${nativeHandleBI.toRadixString(16)}');
+
+    return nativeHandleBIHexInt;
+  }
+
   /////////// debug ////////
 
   /// [type] see [VideoSourceType], only [VideoSourceType.videoSourceCamera], [VideoSourceType.videoSourceRemote] supported

lib/src/impl/api_caller.dart

@@ -29,11 +29,14 @@ void setMockIrisApiEngineIntPtr(int? mockIrisApiEngineIntPtr) {
 const int kBasicResultLength = 64 * 1024;
 
 class CallApiResult {
-  CallApiResult({required this.irisReturnCode, required this.data});
+  CallApiResult({required this.irisReturnCode, required this.data, this.rawData = ''});
 
   final int irisReturnCode;
 
   final Map<String, dynamic> data;
+
+  // TODO(littlegnal): Remove rawData after EP-253 landed.
+  final String rawData;
 }
 
 Uint8List uint8ListFromPtr(int intPtr, int length) {
@@ -448,7 +451,7 @@ class _ApiCallExecutorInternal implements _ApiCallExecutorBase {
 
         final resultMap = Map<String, dynamic>.from(jsonDecode(result));
 
-        return CallApiResult(irisReturnCode: irisReturnCode, data: resultMap);
+        return CallApiResult(irisReturnCode: irisReturnCode, data: resultMap, rawData: result);
       } catch (e) {
         debugPrint(
             '[_ApiCallExecutor] $funcName, params: $params\nerror: ${e.toString()}');