buy warning popup refactor for desktop style/size

lib/pages/buy_view/sub_widgets/buy_warning_popup.dart

@@ -18,16 +18,28 @@ import 'package:stackwallet/widgets/desktop/secondary_button.dart';
 import 'package:stackwallet/widgets/rounded_white_container.dart';
 import 'package:stackwallet/widgets/stack_dialog.dart';
 
-class BuyWarningPopup extends StatelessWidget {
+class BuyWarningPopup extends StatefulWidget {
-  BuyWarningPopup({
+  const BuyWarningPopup({
     Key? key,
     required this.quote,
     this.order,
   }) : super(key: key);
-
   final SimplexQuote quote;
+  final SimplexOrder? order;
+  @override
+  State<BuyWarningPopup> createState() => _BuyWarningPopupState();
+}
+
+class _BuyWarningPopupState extends State<BuyWarningPopup> {
+  late final bool isDesktop;
   SimplexOrder? order;
 
+  String get title => "Buy ${widget.quote.crypto.ticker}";
+  String get message =>
+      "This purchase is provided and fulfilled by Simplex by nuvei "
+      "(a third party). You will be taken to their website. Please follow "
+      "their instructions.";
+
   Future<BuyResponse<SimplexOrder>> newOrder(SimplexQuote quote) async {
     final orderResponse = await SimplexAPI.instance.newOrder(quote);
 
@@ -38,10 +50,6 @@ class BuyWarningPopup extends StatelessWidget {
     return SimplexAPI.instance.redirect(order);
   }
 
-  @override
-  Widget build(BuildContext context) {
-    final isDesktop = Util.isDesktop;
-
   Future<void> _buyInvoice() async {
     await showDialog<void>(
       context: context,
@@ -98,26 +106,16 @@ class BuyWarningPopup extends StatelessWidget {
             : BuyOrderDetailsView(
                 order: order as SimplexOrder,
               );
-          });
+      },
+    );
   }
 
-    return StackDialog(
+  Future<void> onContinue() async {
-      title: "Buy ${quote.crypto.ticker}",
+    BuyResponse<SimplexOrder> orderResponse = await newOrder(widget.quote);
-      message: "This purchase is provided and fulfilled by Simplex by nuvei "
-          "(a third party). You will be taken to their website. Please follow "
-          "their instructions.",
-      leftButton: SecondaryButton(
-        label: "Cancel",
-        onPressed: Navigator.of(context, rootNavigator: isDesktop).pop,
-      ),
-      rightButton: PrimaryButton(
-        label: "Continue",
-        onPressed: () async {
-          BuyResponse<SimplexOrder> orderResponse = await newOrder(quote);
     if (orderResponse.exception == null) {
       await redirect(orderResponse.value as SimplexOrder)
           .then((_response) async {
-              this.order = orderResponse.value as SimplexOrder;
+        order = orderResponse.value as SimplexOrder;
         Navigator.of(context, rootNavigator: isDesktop).pop();
         Navigator.of(context, rootNavigator: isDesktop).pop();
         await _buyInvoice();
@@ -197,7 +195,87 @@ class BuyWarningPopup extends StatelessWidget {
         },
       );
     }
-        },
+  }
+
+  @override
+  void initState() {
+    order = widget.order;
+    isDesktop = Util.isDesktop;
+    super.initState();
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    if (isDesktop) {
+      return DesktopDialog(
+        maxWidth: 580,
+        maxHeight: 350,
+        child: Padding(
+          padding: const EdgeInsets.all(32),
+          child: Column(
+            crossAxisAlignment: CrossAxisAlignment.start,
+            children: [
+              Row(
+                mainAxisAlignment: MainAxisAlignment.spaceBetween,
+                children: [
+                  Text(
+                    title,
+                    style: STextStyles.desktopH3(context),
+                  ),
+                  SizedBox(
+                    width: 64,
+                    height: 32,
+                    child: SvgPicture.asset(
+                      Assets.buy.simplexLogo(context),
+                    ),
+                  ),
+                ],
+              ),
+              const Spacer(),
+              Text(
+                message,
+                style: STextStyles.desktopTextSmall(context),
+              ),
+              const Spacer(
+                flex: 2,
+              ),
+              Row(
+                children: [
+                  Expanded(
+                    child: SecondaryButton(
+                      label: "Cancel",
+                      buttonHeight: ButtonHeight.l,
+                      onPressed:
+                          Navigator.of(context, rootNavigator: isDesktop).pop,
+                    ),
+                  ),
+                  const SizedBox(
+                    width: 16,
+                  ),
+                  Expanded(
+                    child: PrimaryButton(
+                      buttonHeight: ButtonHeight.l,
+                      label: "Continue",
+                      onPressed: onContinue,
+                    ),
+                  ),
+                ],
+              )
+            ],
+          ),
+        ),
+      );
+    } else {
+      return StackDialog(
+        title: title,
+        message: message,
+        leftButton: SecondaryButton(
+          label: "Cancel",
+          onPressed: Navigator.of(context, rootNavigator: isDesktop).pop,
+        ),
+        rightButton: PrimaryButton(
+          label: "Continue",
+          onPressed: onContinue,
         ),
         icon: SizedBox(
           width: 64,
@@ -208,4 +286,5 @@ class BuyWarningPopup extends StatelessWidget {
         ),
       );
     }
+  }
 }