feat: add support for Ethereum EIP-681 URIs in PaymentRequest and implement test coverage (#2375)

* feat: add support for Ethereum EIP-681 URIs in PaymentRequest and implement test coverage

* test: add unit test for EIP-681 URI handling with contract and no chainId [skip-ci]

* fix(CW-1114): rounding error for really large numbers

* fix: wrong decimals for eth fee display

* fix: limit fractional digits to a maximum of `decimals` in `format_fixed` function [skip-ci]

* test: add unit tests for `formatFixed` function

cw_core/lib/format_fixed.dart

@@ -0,0 +1,42 @@
+import 'package:cw_core/parse_fixed.dart';
+
+String formatFixed(BigInt value, int? decimals,
+    {int? fractionalDigits, bool trimZeros = true}) {
+  decimals ??= 0;
+  fractionalDigits ??= decimals;
+
+  var multiplier = getMultiplier(decimals);
+  // Make sure wei is a big number (convert as necessary)
+  var negative = value.isNegative;
+  if (negative) value = value * BigInt.from(-1);
+
+  var fraction = value
+      .modPow(BigInt.one, BigInt.parse(multiplier))
+      .toString()
+      .padLeft(decimals, "0");
+
+  if (fractionalDigits < 0) fractionalDigits = 0;
+  if (fractionalDigits > decimals) fractionalDigits = decimals;
+  fraction = fraction.substring(0, fractionalDigits);
+
+  if (trimZeros) {
+    fraction = removeTrailing("0", fraction);
+  }
+
+  final whole = (value ~/ BigInt.parse(multiplier));
+
+  final valString = fraction.isEmpty ? "$whole" : "$whole.$fraction";
+
+  if (negative) return "-$valString";
+
+  return valString;
+}
+
+String removeTrailing(String pattern, String from) {
+  if (pattern.isEmpty) return from;
+  var i = from.length;
+  while (i > 0 && from.startsWith(pattern, i - pattern.length)) {
+    i -= pattern.length;
+  }
+  return from.substring(0, i);
+}

cw_core/test/format_fixed_test.dart

@@ -0,0 +1,64 @@
+import 'package:cw_core/format_fixed.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+void main() {
+  group('formatFixed', () {
+    group('formatFixed, no fractional digits and trimming zeros', () {
+      test('should format 1000000 into 1',
+          () => expect(formatFixed(BigInt.parse("1000000"), 6), '1'));
+
+      test('should format 1000001 into 1.000001',
+          () => expect(formatFixed(BigInt.parse("1000001"), 6), '1.000001'));
+    });
+
+    group('formatFixed, different fractional digits and trimming zeros', () {
+      test(
+        'should format 1000001 into 1',
+        () => expect(
+            formatFixed(BigInt.parse("1000001"), 6, fractionalDigits: 5), '1'),
+      );
+
+      test(
+        'should format 1000000 into 1, fractionalDigits > decimals',
+        () => expect(
+            formatFixed(BigInt.parse("1000000"), 6, fractionalDigits: 12), '1'),
+      );
+
+      test(
+        'should format 1000001 into 1.000001, fractionalDigits > decimals',
+        () => expect(
+          formatFixed(BigInt.parse("1000001"), 6, fractionalDigits: 12),
+          '1.000001',
+        ),
+      );
+    });
+
+    group('formatFixed, less fractional digits and not trimming zeros', () {
+      test(
+        'should format 1000000 into 1.000000',
+        () => expect(
+          formatFixed(BigInt.parse("1000000"), 6, trimZeros: false),
+          '1.000000',
+        ),
+      );
+
+      test(
+        'should format 1000001 into 1.00000',
+        () => expect(
+          formatFixed(BigInt.parse("1000001"), 6,
+              fractionalDigits: 5, trimZeros: false),
+          '1.00000',
+        ),
+      );
+
+      test(
+        'should format 1000000 into 1.000000',
+        () => expect(
+          formatFixed(BigInt.parse("1000000"), 6,
+              fractionalDigits: 12, trimZeros: false),
+          '1.000000',
+        ),
+      );
+    });
+  });
+}

cw_evm/lib/pending_evm_chain_transaction.dart

@@ -1,6 +1,6 @@
-import 'dart:math';
 import 'dart:typed_data';
 
+import 'package:cw_core/format_fixed.dart';
 import 'package:cw_core/pending_transaction.dart';
 import 'package:web3dart/crypto.dart';
 import 'package:hex/hex.dart' as Hex;
@@ -27,23 +27,17 @@ class PendingEVMChainTransaction with PendingTransaction {
   @override
   String get amountFormatted {
     if (isInfiniteApproval) return "∞";
-    final _amount = (BigInt.parse(amount) / BigInt.from(pow(10, exponent))).toString();
-    return _amount.substring(0, min(10, _amount.length));
+    return formatFixed(BigInt.parse(amount), exponent);
   }
 
   @override
   Future<void> commit() async => await sendTransaction();
 
   @override
-  String get feeFormatted {
-    return "$feeFormattedValue $feeCurrency";
-  }
+  String get feeFormatted => "$feeFormattedValue $feeCurrency";
 
   @override
-  String get feeFormattedValue {
-    final _fee = (fee / BigInt.from(pow(10, 18))).toString();
-    return _fee.substring(0, min(10, _fee.length));
-  }
+  String get feeFormattedValue => formatFixed(fee, 18, fractionalDigits: 10);
 
   @override
   String get hex => bytesToHex(signedTransaction, include0x: true);
@@ -53,7 +47,7 @@ class PendingEVMChainTransaction with PendingTransaction {
     final String eip1559Hex = '0x02${hex.substring(2)}';
     final Uint8List bytes = Uint8List.fromList(Hex.HEX.decode(eip1559Hex.substring(2)));
 
-    var txid = keccak256(bytes);
+    final txid = keccak256(bytes);
 
     return '0x${Hex.HEX.encode(txid)}';
   }

lib/utils/payment_request.dart

@@ -1,4 +1,6 @@
 import 'package:cake_wallet/nano/nano.dart';
+import 'package:cake_wallet/view_model/wallet_address_list/wallet_address_list_view_model.dart';
+import 'package:cw_core/format_fixed.dart';
 
 class PaymentRequest {
   PaymentRequest(this.address, this.amount, this.note, this.scheme, this.pjUri,
@@ -26,12 +28,21 @@ class PaymentRequest {
       callbackUrl = uri.queryParameters['callback'];
       callbackMessage = uri.queryParameters['callbackMessage'];
       walletType = uri.queryParameters['type'];
+
+      if (scheme == "ethereum") {
+        final paymentUri = ERC681URI.fromUri(uri);
+
+        address = paymentUri.address;
+        amount = paymentUri.amount;
+      }
     }
 
     if (scheme == "nano-gpt") {
       scheme = walletType ?? "nano";
     }
 
+
+
     if (nano != null) {
       if (amount.isNotEmpty) {
         if (address.contains("nano")) {
@@ -61,3 +72,54 @@ class PaymentRequest {
   final String? callbackUrl;
   final String? callbackMessage;
 }
+
+class ERC681URI extends PaymentURI {
+  final int chainId;
+  final String? contractAddress;
+
+  ERC681URI({
+    required this.chainId,
+    required super.address,
+    required super.amount,
+    required this.contractAddress,
+  });
+
+  factory ERC681URI.fromUri(Uri uri) {
+    final (isContract, targetAddress) = _getTargetAddress(uri.path);
+    final chainId = _getChainID(uri.path);
+
+    final address = isContract ? uri.queryParameters["address"] ?? '' : targetAddress;
+    final amount = isContract
+        ? uri.queryParameters["uint256"]
+        : uri.queryParameters["value"];
+
+    var formatedAmount = "";
+
+    if (amount != null) {
+      formatedAmount = formatFixed(BigInt.parse(amount), 18);
+    } else {
+      formatedAmount = uri.queryParameters["amount"] ?? "";
+    }
+
+    return ERC681URI(
+      chainId: chainId,
+      address: address,
+      amount: formatedAmount,
+      contractAddress: isContract ? targetAddress : null,
+    );
+  }
+
+  static int _getChainID(String path) {
+    return int.parse(RegExp(
+      r'@\d*',
+    ).firstMatch(path)?.group(0)?.replaceAll("@", "") ??
+        "1");
+  }
+
+  static (bool, String) _getTargetAddress(String path) {
+    final targetAddress = RegExp(r'^(0x)?[0-9a-f]{40}', caseSensitive: false)
+        .firstMatch(path)!
+        .group(0)!;
+    return (path.contains("/"), targetAddress);
+  }
+}

test/utils/payment_request_test.dart

@@ -0,0 +1,61 @@
+import 'package:cake_wallet/utils/payment_request.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+void main() {
+  group('PaymentRequest', () {
+    group('Ethereum URIs', () {
+      test("extract address and amount from EIP681 Uri with contract", () {
+        final uri = Uri.parse(
+            "ethereum:0x2791Bca1f2de4661ED88A30C99A7a9449Aa84174@1/transfer?address=0xCfc1650da7C961FD82998e7e30ca5f699D0aBf41&uint256=2000000000000000000");
+        final paymentRequest = PaymentRequest.fromUri(uri);
+
+        expect(paymentRequest.address, "0xCfc1650da7C961FD82998e7e30ca5f699D0aBf41");
+        expect(paymentRequest.amount, "2");
+      });
+
+      test("extract address and amount from EIP681 Uri", () {
+        final uri = Uri.parse(
+            "ethereum:0xCfc1650da7C961FD82998e7e30ca5f699D0aBf41@1?value=2000000000000000000");
+        final paymentRequest = PaymentRequest.fromUri(uri);
+
+        expect(paymentRequest.address, "0xCfc1650da7C961FD82998e7e30ca5f699D0aBf41");
+        expect(paymentRequest.amount, "2");
+      });
+
+      test("extract address and amount from Cake Style Uri", () {
+        final uri =
+            Uri.parse("ethereum:0xCfc1650da7C961FD82998e7e30ca5f699D0aBf41@1?amount=2.00");
+        final paymentRequest = PaymentRequest.fromUri(uri);
+
+        expect(paymentRequest.address, "0xCfc1650da7C961FD82998e7e30ca5f699D0aBf41");
+        expect(paymentRequest.amount, "2.00");
+      });
+
+      test("extract address from EIP681 Uri with contract", () {
+        final uri = Uri.parse(
+            "ethereum:0x2791Bca1f2de4661ED88A30C99A7a9449Aa84174@1/transfer?address=0xCfc1650da7C961FD82998e7e30ca5f699D0aBf41");
+        final paymentRequest = PaymentRequest.fromUri(uri);
+
+        expect(paymentRequest.address, "0xCfc1650da7C961FD82998e7e30ca5f699D0aBf41");
+        expect(paymentRequest.amount, "");
+      });
+
+      test("extract address and amount from EIP681 Uri with contract and no chainId", () {
+        final uri = Uri.parse(
+            "ethereum:0x1234567890abcdef1234567890abcdef12345678/transfer?address=0xabcdef1234567890abcdef1234567890abcdef12&uint256=1000000000000000000");
+        final paymentRequest = PaymentRequest.fromUri(uri);
+
+        expect(paymentRequest.address, "0xabcdef1234567890abcdef1234567890abcdef12");
+        expect(paymentRequest.amount, "1");
+      });
+
+      test("extract address from minimal EIP681 Uri", () {
+        final uri = Uri.parse("ethereum:0xCfc1650da7C961FD82998e7e30ca5f699D0aBf41");
+        final paymentRequest = PaymentRequest.fromUri(uri);
+
+        expect(paymentRequest.address, "0xCfc1650da7C961FD82998e7e30ca5f699D0aBf41");
+        expect(paymentRequest.amount, "");
+      });
+    });
+  });
+}