[DO NOT MERGE] Extra confirm callback proposal for Apple Pay

pay/example/lib/main.dart

@@ -72,8 +72,10 @@ class _PaySampleAppState extends State<PaySampleApp> {
     debugPrint(paymentResult.toString());
   }
 
-  void onApplePayResult(paymentResult) {
+  onApplePayResultWithConfirm(
+      Map<String, dynamic> paymentResult, PaymentConfirmation handler) {
     debugPrint(paymentResult.toString());
+    handler.confirmPayment(true);
   }
 
   @override
@@ -149,7 +151,7 @@ class _PaySampleAppState extends State<PaySampleApp> {
             style: ApplePayButtonStyle.black,
             type: ApplePayButtonType.buy,
             margin: const EdgeInsets.only(top: 15.0),
-            onPaymentResult: onApplePayResult,
+            onPaymentResultWithConfirm: onApplePayResultWithConfirm,
             loadingIndicator: const Center(
               child: CircularProgressIndicator(),
             ),

pay/lib/src/widgets/apple_pay_button.dart

@@ -3,6 +3,18 @@
 
 part of '../../pay.dart';
 
+class PaymentConfirmation {
+  final Pay _payClient;
+  PaymentConfirmation(Pay payClient) : _payClient = payClient;
+
+  void confirmPayment(bool completedSuccessfully) {
+    _payClient.userCanPay(PayProvider.google_pay);
+  }
+}
+
+typedef PaymentConfirmCallback = Function(
+    Map<String, dynamic> result, PaymentConfirmation handler);
+
 /// A widget to show the Apple Pay button according to the rules and constraints
 /// specified in [PayButton].
 ///
@@ -29,7 +41,8 @@ class ApplePayButton extends PayButton {
         'Prefer to use [paymentConfiguration]. Take a look at the readme to see examples')
     String? paymentConfigurationAsset,
     PaymentConfiguration? paymentConfiguration,
-    required void Function(Map<String, dynamic> result) onPaymentResult,
+    PaymentResultCallback? onPaymentResult,
+    PaymentConfirmCallback? onPaymentResultWithConfirm,
     required List<PaymentItem> paymentItems,
     ApplePayButtonStyle style = ApplePayButtonStyle.black,
     ApplePayButtonType type = ApplePayButtonType.plain,
@@ -59,6 +72,12 @@ class ApplePayButton extends PayButton {
         style: style,
         type: type,
         onPressed: _defaultOnPressed(onPressed, paymentItems));
+
+    paymentCallback = (result) => {
+          onPaymentResult?.call(result),
+          onPaymentResultWithConfirm?.call(
+              result, PaymentConfirmation(_payClient))
+        };
   }
 
   @override

pay/lib/src/widgets/google_pay_button.dart

@@ -28,7 +28,7 @@ class GooglePayButton extends PayButton {
         'Prefer to use [paymentConfiguration]. Take a look at the readme to see examples')
     String? paymentConfigurationAsset,
     PaymentConfiguration? paymentConfiguration,
-    required void Function(Map<String, dynamic> result) onPaymentResult,
+    PaymentResultCallback? onPaymentResult,
     required List<PaymentItem> paymentItems,
     GooglePayButtonType type = GooglePayButtonType.pay,
     double width = RawGooglePayButton.minimumButtonWidth,

pay/lib/src/widgets/pay_button.dart

@@ -14,6 +14,8 @@
 
 part of '../../pay.dart';
 
+typedef PaymentResultCallback = Function(Map<String, dynamic> result);
+
 /// A widget that handles the API logic to facilitate the integration.
 ///
 /// This widget provides an alternative UI-based integration path that wraps
@@ -27,13 +29,13 @@ part of '../../pay.dart';
 /// method which starts the payment process.
 abstract class PayButton extends StatefulWidget {
   /// A resident client to issue requests against the APIs.
-  late final Pay _payClient;
+  final Pay _payClient;
 
   /// Specifies the payment provider supported by the button
   final PayProvider buttonProvider;
 
   /// A function called when the payment process yields a result.
-  final void Function(Map<String, dynamic> result) onPaymentResult;
+  late final PaymentResultCallback? paymentCallback;
 
   final double width;
   final double height;
@@ -59,7 +61,7 @@ abstract class PayButton extends StatefulWidget {
         'Prefer to use [paymentConfiguration]. Take a look at the readme to see examples')
     final String? paymentConfigurationAsset,
     final PaymentConfiguration? paymentConfiguration,
-    this.onPaymentResult,
+    this.paymentCallback,
     this.width,
     this.height,
     this.margin,
@@ -83,7 +85,7 @@ abstract class PayButton extends StatefulWidget {
       try {
         final result =
             await _payClient.showPaymentSelector(buttonProvider, paymentItems);
-        onPaymentResult(result);
+        paymentCallback?.call(result);
       } catch (error) {
         onError?.call(error);
       }