update invoice

lib/pages/discount/discount_list.dart

@@ -11,6 +11,9 @@ import 'package:provider/provider.dart';
 import 'discount_editor.dart';
 
 class DiscountList extends StatefulWidget {
+  final bool selected;
+
+  const DiscountList({Key key, this.selected}) : super(key: key);
   @override
   _DiscountListState createState() => _DiscountListState();
 }
@@ -50,13 +53,15 @@ class _DiscountListState extends State<DiscountList> {
             var discount = discountModel.discounts[index];
             return InkWell(
               onTap: () {
-                Navigator.push(
-                  context,
-                  CupertinoPageRoute(
-                      builder: (context) => DiscountEditor(
-                            discount: discount,
-                          )),
-                );
+                widget.selected
+                    ? Navigator.pop(context, discount)
+                    : Navigator.push(
+                        context,
+                        CupertinoPageRoute(
+                            builder: (context) => DiscountEditor(
+                                  discount: discount,
+                                )),
+                      );
               },
               child: Padding(
                 padding: const EdgeInsets.all(10.0),