Remove prefix from QR code scans (#121)

* Remove prefix from QR code scans

* Remove query parameters from address and parse amount

Did not modify PaymentUriInfo to avoid issues with segwit variants

lib/screens/portfolio/coin_detail/steps_withdraw.dart/amount_address_step/amount_address_step.dart

@@ -188,6 +188,10 @@ class _AmountAddressStepState extends State<AmountAddressStep> {
     widget.addressController.text = address;
   }
 
+  set qrAmount(String amount) {
+    widget.amountController.text = amount;
+  }
+
   void showWrongCoinDialog(PaymentUriInfo uriInfo) {
     dialogBloc.dialog = showDialog<void>(
         context: context,
@@ -301,15 +305,17 @@ class _AmountAddressStepState extends State<AmountAddressStep> {
         barcode = 'Error';
       });
     } else {
-      final address = result;
-      final uri = Uri.tryParse(address.trim());
+      final String address = getAddressFromUri(result.trim());
+      final String amount = getParameterValue(result.trim(), 'amount');
+      final Uri uri = Uri.tryParse(result.trim());
 
       setState(() {
         final PaymentUriInfo uriInfo = PaymentUriInfo.fromUri(uri);
         if (uriInfo != null) {
           handlePaymentData(uriInfo);
         } else {
           handleQrAdress(address);
+          qrAmount = amount ?? '';
         }
       });
     }

lib/utils/utils.dart

@@ -711,6 +711,35 @@ class PaymentUriInfo {
   final String amount;
 }
 
+/// Returns the value of a [parameter] from the [address].
+/// Returns null if the [parameter] is not found.
+/// [address] is expected to be a blockchain address or URL with parameters,
+/// e.g. '?amount=123'
+///
+/// Example usage:
+/// ```dart
+/// getParameterValue('litecoin:NPZcaiggQTy6uxL?amount=0.2', 'amount') == '0.2'
+/// ```
+String getParameterValue(String address, String parameter) {
+  final RegExp regExp = RegExp('(?<=$parameter=)(.*?)(?=&|\$)');
+  final RegExpMatch match = regExp.firstMatch(address);
+  return match?.group(0);
+}
+
+/// Returns the address from the [uri].
+/// Returns the [uri] if no address is found.
+/// [uri] is expected to be a blockchain address or URL with parameters,
+/// e.g. '?amount=123'
+/// Example usage:
+/// ```dart
+/// getAddressFromUri('litecoin:NPZcaiggQTy6uxL?amount=0.2') == 'NPZcaiggQTy6uxL'
+/// ```
+String getAddressFromUri(String uri) {
+  final RegExp regExp = RegExp(r'(?<=:)(.*?)(?=\?|$)');
+  final RegExpMatch match = regExp.firstMatch(uri);
+  return match?.group(0) ?? uri.split(':').last;
+}
+
 void showUriDetailsDialog(
     BuildContext context, PaymentUriInfo uriInfo, Function callbackIfAccepted) {
   if (uriInfo == null) return;

test/utils/utils_test.dart

@@ -0,0 +1,50 @@
+import 'package:flutter_test/flutter_test.dart';
+import 'package:komodo_dex/model/coin.dart';
+import 'package:komodo_dex/utils/utils.dart';
+
+void main() {
+  group('removeBlockchainPrefix', () {
+    test('removes blockchain prefix from address', () {
+      const String address = 'eth:0x1234567890abcdef';
+      final String result = getAddressFromUri(address);
+      expect(result, '0x1234567890abcdef');
+    });
+
+    test('removes blackcoin prefix from address', () {
+      const String address = 'blackcoin:B8Q9aZ4Mz1ZwWYaknJdZ8t3Z6z9F3Fz1Zz';
+      final String result = getAddressFromUri(address);
+      expect(result, 'B8Q9aZ4Mz1ZwWYaknJdZ8t3Z6z9F3Fz1Zz');
+    });
+
+    test('returns the same address if no prefix is present', () {
+      const String address = '0x1234567890abcdef';
+      final String result = getAddressFromUri(address);
+      expect(result, '0x1234567890abcdef');
+    });
+  });
+
+  group('getParameterValue', () {
+    test('returns the parameter value from the address', () {
+      const String address =
+          'eth:0x1234567890abcdef?param1=value1&param2=value2';
+      const String parameter = 'param1';
+      final String result = getParameterValue(address, parameter);
+      expect(result, 'value1');
+    });
+
+    test('returns null if the parameter is not present in the address', () {
+      const String address =
+          'eth:0x1234567890abcdef?param1=value1&param2=value2';
+      const String parameter = 'param3';
+      final String result = getParameterValue(address, parameter);
+      expect(result, isNull);
+    });
+
+    test('returns null if the address does not contain any parameters', () {
+      const String address = 'eth:0x1234567890abcdef';
+      const String parameter = 'param1';
+      final String result = getParameterValue(address, parameter);
+      expect(result, isNull);
+    });
+  });
+}