feat: [DRGO - 76] Adding subscription for crypto estimations

lib/api/response/crypto_estimations_response_extended.dart

@@ -0,0 +1,57 @@
+import 'package:deriv_dependency_injector/dependency_injector.dart';
+import 'package:flutter_deriv_api/api/exceptions/base_api_exception.dart';
+import 'package:flutter_deriv_api/api/models/base_exception_model.dart';
+import 'package:flutter_deriv_api/api/response/crypto_estimations_response_result.dart';
+import 'package:flutter_deriv_api/basic_api/generated/crypto_estimations_receive.dart';
+import 'package:flutter_deriv_api/basic_api/generated/crypto_estimations_send.dart';
+import 'package:flutter_deriv_api/basic_api/generated/forget_receive.dart';
+import 'package:flutter_deriv_api/basic_api/response.dart';
+import 'package:flutter_deriv_api/helpers/miscellaneous_helper.dart';
+import 'package:flutter_deriv_api/services/connection/api_manager/base_api.dart';
+import 'package:flutter_deriv_api/services/connection/call_manager/base_call_manager.dart';
+
+/// Extended functionality for [CryptoEstimationsResponse] class.
+
+class CryptoEstimationsResponseExtended extends CryptoEstimationsResponse {
+  static final BaseAPI _api = Injector()<BaseAPI>();
+
+  /// This will subscribe to crypto estimations.<br>
+  /// Inside [CryptoEstimationsRequest] class:
+  /// Incase of error, It will throw [BaseAPIException].
+  static Stream<CryptoEstimationsResponse?> subscribeToCryptoEstimates(
+    CryptoEstimationsRequest request, {
+    RequestCompareFunction? comparePredicate,
+  }) =>
+      _api
+          .subscribe(request: request, comparePredicate: comparePredicate)!
+          .map<CryptoEstimationsResponse?>(
+        (Response response) {
+          checkException(
+            response: response,
+            exceptionCreator: ({BaseExceptionModel? baseExceptionModel}) =>
+                BaseAPIException(baseExceptionModel: baseExceptionModel),
+          );
+
+          if (response is CryptoEstimationsReceive) {
+            return CryptoEstimationsResponse.fromJson(
+                response.cryptoEstimations, response.subscription);
+          } else {
+            throw Exception('Bad response received');
+          }
+        },
+      );
+
+  /// unsubscribe from the subscribed Crypto Estimates <br>
+  /// In case of error, It will throw [BaseAPIException].
+  static Future<bool> unsubscribeFromCryptoEstimates(
+      String subscriptionId) async {
+    final ForgetReceive response =
+        await _api.unsubscribe(subscriptionId: subscriptionId);
+    checkException(
+      response: response,
+      exceptionCreator: ({BaseExceptionModel? baseExceptionModel}) =>
+          BaseAPIException(baseExceptionModel: baseExceptionModel),
+    );
+    return response.forget!;
+  }
+}