completed first web iteration

lib/screens/gateway/gateway_screen.dart

@@ -1,5 +1,3 @@
-import 'dart:io';
-
 import 'package:flutter/material.dart';
 import 'package:flutter_dotenv/flutter_dotenv.dart';
 import 'package:go_router/go_router.dart';
@@ -17,6 +15,7 @@ class _GatewayScreenState extends State<GatewayScreen> {
   late WebViewController _webViewController;
   late GatewayController controller;
   late String url;
+  String? sessionID;
 
   bool integrationStarted = false;
 
@@ -24,63 +23,71 @@ class _GatewayScreenState extends State<GatewayScreen> {
   void initState() {
     super.initState();
     controller = GatewayController(context);
+    // https://na.gateway.mastercard.com/checkout/pay/SESSION0002220827459I8059951J88?checkoutVersion=1.0.0
+
     url = controller.transactionController.model.receiptData?['targetUrl'];
-    _initWebView(url);
+
+    _initWebView();
+  }
+
+  void _initWebView() async {
+    _webViewController = WebViewController()
+      ..setJavaScriptMode(JavaScriptMode.unrestricted)
+      ..setNavigationDelegate(
+        NavigationDelegate(
+          onProgress: (int progress) {
+            // Update loading bar.
+          },
+          onPageStarted: (String url) {
+            controller.startLoading();
+          },
+          onPageFinished: (String url) {
+            controller.finishLoading();
+          },
+          onHttpError: (HttpResponseError error) {},
+          onWebResourceError: (WebResourceError error) {},
+          onUrlChange: (UrlChange url) async {
+            print("URL Changed to ${url.url!}");
+
+            _navigateWhenDone(url.url!);
+          },
+        ),
+      )
+      ..loadRequest(Uri.parse(url));
 
     bool simulate = bool.parse(dotenv.env['SIMULATE_PAYMENT_SUCCESS']!);
-    if(simulate) {
-      sleep(Duration(seconds: 10));
+    if (simulate) {
+      await Future.delayed(Duration(seconds: 10));
       String targetUrl = url.replaceAll("/pay/", "/receipt/");
       _webViewController.loadRequest(Uri.parse(targetUrl));
     }
   }
 
-  void _initWebView(String url) {
-    _webViewController =
-        WebViewController()
-          ..setJavaScriptMode(JavaScriptMode.unrestricted)
-          ..setNavigationDelegate(
-            NavigationDelegate(
-              onProgress: (int progress) {
-                // Update loading bar.
-              },
-              onPageStarted: (String url) {
-                controller.startLoading();
-              },
-              onPageFinished: (String url) {
-                controller.finishLoading();
-              },
-              onHttpError: (HttpResponseError error) {},
-              onWebResourceError: (WebResourceError error) {},
-              onUrlChange: (UrlChange url) async {
-                print("URL Changed to ${url.url!}");
+  void _navigateWhenDone(String url) {
+    if (url.contains("/checkout/receipt/")) {
+      if (integrationStarted) {
+        return;
+      }
 
-                if(url.url!.contains("/checkout/receipt/")){
-                  if(integrationStarted) {
-                    return;
-                  }
+      ScaffoldMessenger.of(context).showSnackBar(
+        SnackBar(
+          content: Text(
+            "Payment was successful, please wait while we process your order.",
+          ),
+          behavior: SnackBarBehavior.floating,
+          backgroundColor: Colors.black87,
+          duration: const Duration(seconds: 10),
+        ),
+      );
 
-                  ScaffoldMessenger.of(context).showSnackBar(
-                    SnackBar(
-                      content: Text("Payment was successful, please wait while we process your order."),
-                      behavior: SnackBarBehavior.floating,
-                      backgroundColor: Colors.black87,
-                      duration: const Duration(seconds: 10),
-                    ),
-                  );
+      setState(() {
+        integrationStarted = true;
+      });
 
-                  setState(() {
-                    integrationStarted = true;
-                  });
-
-                  WidgetsBinding.instance.addPostFrameCallback((_) {
-                    context.go('/integration');
-                  });
-                }
-              }
-            ),
-          )
-          ..loadRequest(Uri.parse(url));
+      WidgetsBinding.instance.addPostFrameCallback((_) {
+        context.go('/integration');
+      });
+    }
   }
 
   @override
@@ -94,15 +101,14 @@ class _GatewayScreenState extends State<GatewayScreen> {
     return Scaffold(
       appBar: AppBar(
         title: const Text('Complete your payment'),
-        leading:
-            context.canPop()
-                ? IconButton(
-                  onPressed: () {
-                    context.pop();
-                  },
-                  icon: const Icon(Icons.arrow_back),
-                )
-                : SizedBox.shrink(),
+        leading: context.canPop()
+            ? IconButton(
+                onPressed: () {
+                  context.pop();
+                },
+                icon: const Icon(Icons.arrow_back),
+              )
+            : SizedBox.shrink(),
       ),
       body: ListenableBuilder(
         listenable: controller,
@@ -112,9 +118,12 @@ class _GatewayScreenState extends State<GatewayScreen> {
               context.go('/integration');
             });
           }
+
           return controller.model.isLoading
               ? const Center(child: CircularProgressIndicator(strokeWidth: 5))
-              : WebViewWidget(controller: _webViewController);
+              : SizedBox.expand(
+                  child: WebViewWidget(controller: _webViewController),
+                );
         },
       ),
     );