ramin/make_proxy_aware_connection_configurable (#310)

* test HttpOverrides to pass the connection through the proxy server

* get system proxy and add it to HttpOverride

* add onProxy found callback

* create custom HttpClient for the websocket connection

* use flutter-system proxy dep

* make onProxyFound optional

* code cleanup

* revert unnessary changes

* remove debugging code

* remove debugging code

* use proxyAwareConnection flag in BinaryAPI

Author: ramin-deriv

lib/services/connection/api_manager/binary_api.dart

@@ -27,11 +27,15 @@ class BinaryAPI extends BaseAPI {
   BinaryAPI({
     String? key,
     bool enableDebug = false,
+    this.proxyAwareConnection = false,
   }) : super(key: key ?? '${UniqueKey()}', enableDebug: enableDebug);
 
   static const Duration _disconnectTimeOut = Duration(seconds: 5);
   static const Duration _websocketConnectTimeOut = Duration(seconds: 10);
 
+  /// A flag to indicate if the connection is proxy aware.
+  final bool proxyAwareConnection;
+
   /// Represents the active websocket connection.
   ///
   /// This is used to send and receive data from the websocket server.
@@ -77,10 +81,15 @@ class BinaryAPI extends BaseAPI {
     _logDebugInfo('connecting to $uri.');
 
     await _setUserAgent();
-    final String proxy = await FlutterSystemProxy.findProxyFromEnvironment(
-        uri.toString().replaceAll('wss', 'https'));
 
-    final HttpClient client = HttpClient()..findProxy = (Uri uri) => proxy;
+    HttpClient? client;
+
+    if (proxyAwareConnection) {
+      final String proxy = await FlutterSystemProxy.findProxyFromEnvironment(
+          uri.toString().replaceAll('wss', 'https'));
+
+      client = HttpClient()..findProxy = (Uri uri) => proxy;
+    }
 
     // Initialize connection to websocket server.
     _webSocketChannel = IOWebSocketChannel.connect('$uri',

lib/state/connection/connection_cubit.dart

@@ -22,12 +22,15 @@ class ConnectionCubit extends Cubit<ConnectionState> {
     ConnectionInformation connectionInformation, {
     BaseAPI? api,
     this.enableDebug = false,
+        // TODO(NA): Refactor to only get BinaryAPI instance. and printResponse and proxyAwareConnection can be part of BinaryAPI only.
     this.printResponse = false,
+    this.proxyAwareConnection = false,
   }) : super(const ConnectionInitialState()) {
     APIInitializer().initialize(
       api: api ??
           BinaryAPI(
             key: _key,
+            proxyAwareConnection: proxyAwareConnection,
             enableDebug: enableDebug,
           ),
     );
@@ -55,6 +58,9 @@ class ConnectionCubit extends Cubit<ConnectionState> {
   /// Default value is `false`.
   final bool printResponse;
 
+  /// A flag to indicate if the connection is proxy aware.
+  final bool proxyAwareConnection;
+
   // In some devices like Samsung J6 or Huawei Y7, the call manager doesn't response to the ping call less than 5 sec.
   final Duration _pingTimeout = const Duration(seconds: 5);