feat(deuro): Enhance gas fee handling and error management for Deuro Savings Transactions.

This change:
- Introduces DeuroGasFeeException to handle insufficient ETH for gas fees.
- Adds check for ETH balance before savings transactions to prevent failures due to insufficient funds.
- Updates savings transaction methods to include error handling.
- Adds UI feedback for transaction failures in DEuroSavingsPage.

cw_ethereum/lib/deuro/deuro_savings.dart

@@ -6,12 +6,12 @@ import 'package:cw_core/crypto_currency.dart';
 import 'package:cw_ethereum/deuro/deuro_savings_contract.dart';
 import 'package:cw_ethereum/ethereum_wallet.dart';
 import 'package:cw_evm/contract/erc20.dart';
+import 'package:cw_evm/evm_chain_exceptions.dart';
 import 'package:cw_evm/evm_chain_transaction_priority.dart';
 import 'package:cw_evm/pending_evm_chain_transaction.dart';
 import 'package:web3dart/web3dart.dart';
 
-const String savingsGatewayAddress =
-    "0x073493d73258C4BEb6542e8dd3e1b2891C972303";
+const String savingsGatewayAddress = "0x073493d73258C4BEb6542e8dd3e1b2891C972303";
 
 const String dEuroAddress = "0xbA3f535bbCcCcA2A154b573Ca6c5A49BAAE0a3ea";
 
@@ -35,81 +35,123 @@ class DEuro {
         client: client,
       );
 
-  final frontendCode =
-      Uint8List.fromList(sha256.convert(utf8.encode("wallet")).bytes);
+  final frontendCode = Uint8List.fromList(sha256.convert(utf8.encode("wallet")).bytes);
 
-  EthereumAddress get _address =>
-      EthereumAddress.fromHex(_wallet.walletAddresses.primaryAddress);
+  EthereumAddress get _address => EthereumAddress.fromHex(_wallet.walletAddresses.primaryAddress);
 
   Future<BigInt> get savingsBalance async =>
       (await _savingsGateway.savings(accountOwner: _address)).saved;
 
-  Future<BigInt> get accruedInterest =>
-      _savingsGateway.accruedInterest(accountOwner: _address);
+  Future<BigInt> get accruedInterest => _savingsGateway.accruedInterest(accountOwner: _address);
 
   Future<BigInt> get interestRate => _savingsGateway.currentRatePPM();
 
-  Future<BigInt> get approvedBalance =>
-      _dEuro.allowance(_address, _savingsGateway.self.address);
+  Future<BigInt> get approvedBalance => _dEuro.allowance(_address, _savingsGateway.self.address);
 
-  Future<PendingEVMChainTransaction> depositSavings(
-      BigInt amount, EVMChainTransactionPriority priority) async {
-    final signedTransaction = await _savingsGateway.save(
-      (amount: amount, frontendCode: frontendCode),
-      credentials: _wallet.evmChainPrivateKey,
-    );
+  Future<void> _checkEthBalanceForGasFees(EVMChainTransactionPriority priority) async {
+    final ethBalance = await _wallet.getWeb3Client()!.getBalance(_address);
+    final currentBalance = ethBalance.getInWei;
 
-    final fee = await _wallet.calculateActualEstimatedFeeForCreateTransaction(
-      amount: amount,
+    final gasFeesModel = await _wallet.calculateActualEstimatedFeeForCreateTransaction(
+      amount: BigInt.zero,
       contractAddress: _savingsGateway.self.address.hexEip55,
       receivingAddressHex: _savingsGateway.self.address.hexEip55,
       priority: priority,
-      data: _savingsGateway.self.abi.functions[17]
-          .encodeCall([amount, frontendCode]),
+      data: _savingsGateway.self.abi.functions[17].encodeCall([BigInt.zero, frontendCode]),
     );
 
-    final sendTransaction =
-        () => _wallet.getWeb3Client()!.sendRawTransaction(signedTransaction);
+    final estimatedGasFee = BigInt.from(gasFeesModel.estimatedGasFee);
 
-    return PendingEVMChainTransaction(
-        sendTransaction: sendTransaction,
-        signedTransaction: signedTransaction,
-        fee: BigInt.from(fee.estimatedGasFee),
-        amount: amount.toString(),
-        exponent: 18);
+    final requiredBalance = estimatedGasFee;
+
+    if (currentBalance < requiredBalance) {
+      throw DeuroGasFeeException(
+        requiredGasFee: requiredBalance,
+        currentBalance: currentBalance,
+      );
+    }
+  }
+
+  Future<PendingEVMChainTransaction> depositSavings(
+      BigInt amount, EVMChainTransactionPriority priority) async {
+    try {
+      await _checkEthBalanceForGasFees(priority);
+
+      final signedTransaction = await _savingsGateway.save(
+        (amount: amount, frontendCode: frontendCode),
+        credentials: _wallet.evmChainPrivateKey,
+      );
+
+      final fee = await _wallet.calculateActualEstimatedFeeForCreateTransaction(
+        amount: amount,
+        contractAddress: _savingsGateway.self.address.hexEip55,
+        receivingAddressHex: _savingsGateway.self.address.hexEip55,
+        priority: priority,
+        data: _savingsGateway.self.abi.functions[17].encodeCall([amount, frontendCode]),
+      );
+
+      final sendTransaction = () => _wallet.getWeb3Client()!.sendRawTransaction(signedTransaction);
+
+      return PendingEVMChainTransaction(
+          sendTransaction: sendTransaction,
+          signedTransaction: signedTransaction,
+          fee: BigInt.from(fee.estimatedGasFee),
+          amount: amount.toString(),
+          exponent: 18);
+    } catch (e) {
+      if (e.toString().contains('insufficient funds for gas')) {
+        final ethBalance = await _wallet.getWeb3Client()!.getBalance(_address);
+        throw DeuroGasFeeException(
+          currentBalance: ethBalance.getInWei,
+        );
+      }
+      rethrow;
+    }
   }
 
   Future<PendingEVMChainTransaction> withdrawSavings(
       BigInt amount, EVMChainTransactionPriority priority) async {
-    final signedTransaction = await _savingsGateway.withdraw(
-      (target: _address, amount: amount, frontendCode: frontendCode),
-      credentials: _wallet.evmChainPrivateKey,
-    );
+    try {
+      await _checkEthBalanceForGasFees(priority);
 
-    final fee = await _wallet.calculateActualEstimatedFeeForCreateTransaction(
-      amount: amount,
-      contractAddress: _savingsGateway.self.address.hexEip55,
-      receivingAddressHex: _savingsGateway.self.address.hexEip55,
-      priority: priority,
-      data: _savingsGateway.self.abi.functions[17]
-          .encodeCall([amount, frontendCode]),
-    );
+      final signedTransaction = await _savingsGateway.withdraw(
+        (target: _address, amount: amount, frontendCode: frontendCode),
+        credentials: _wallet.evmChainPrivateKey,
+      );
 
-    final sendTransaction =
-        () => _wallet.getWeb3Client()!.sendRawTransaction(signedTransaction);
+      final fee = await _wallet.calculateActualEstimatedFeeForCreateTransaction(
+        amount: amount,
+        contractAddress: _savingsGateway.self.address.hexEip55,
+        receivingAddressHex: _savingsGateway.self.address.hexEip55,
+        priority: priority,
+        data: _savingsGateway.self.abi.functions[17].encodeCall([amount, frontendCode]),
+      );
 
-    return PendingEVMChainTransaction(
-        sendTransaction: sendTransaction,
-        signedTransaction: signedTransaction,
-        fee: BigInt.from(fee.estimatedGasFee),
-        amount: amount.toString(),
-        exponent: 18);
+      final sendTransaction = () => _wallet.getWeb3Client()!.sendRawTransaction(signedTransaction);
+
+      return PendingEVMChainTransaction(
+          sendTransaction: sendTransaction,
+          signedTransaction: signedTransaction,
+          fee: BigInt.from(fee.estimatedGasFee),
+          amount: amount.toString(),
+          exponent: 18);
+    } catch (e) {
+      if (e.toString().contains('insufficient funds for gas')) {
+        final ethBalance = await _wallet.getWeb3Client()!.getBalance(_address);
+        throw DeuroGasFeeException(
+          currentBalance: ethBalance.getInWei,
+        );
+      }
+      rethrow;
+    }
   }
 
   // Set an infinite approval to save gas in the future
-  Future<PendingEVMChainTransaction> enableSavings(
-          EVMChainTransactionPriority priority) async =>
-      (await _wallet.createApprovalTransaction(
+  Future<PendingEVMChainTransaction> enableSavings(EVMChainTransactionPriority priority) async {
+    try {
+      await _checkEthBalanceForGasFees(priority);
+
+      return (await _wallet.createApprovalTransaction(
         BigInt.parse(
           'ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff',
           radix: 16,
@@ -118,4 +160,14 @@ class DEuro {
         CryptoCurrency.deuro,
         priority,
       )) as PendingEVMChainTransaction;
+    } catch (e) {
+      if (e.toString().contains('insufficient funds for gas')) {
+        final ethBalance = await _wallet.getWeb3Client()!.getBalance(_address);
+        throw DeuroGasFeeException(
+          currentBalance: ethBalance.getInWei,
+        );
+      }
+      rethrow;
+    }
+  }
 }

cw_evm/lib/evm_chain_exceptions.dart

@@ -22,3 +22,32 @@ class EVMChainTransactionFeesException implements Exception {
   @override
   String toString() => exceptionMessage;
 }
+
+class DeuroGasFeeException implements Exception {
+  final String exceptionMessage;
+  final BigInt? requiredGasFee;
+  final BigInt? currentBalance;
+
+  DeuroGasFeeException({
+    this.requiredGasFee,
+    this.currentBalance,
+  }) : exceptionMessage = _buildMessage(requiredGasFee, currentBalance);
+
+  static String _buildMessage(BigInt? requiredGasFee, BigInt? currentBalance) {
+    const baseMessage = 'Insufficient ETH for gas fees.';
+    const addEthMessage = ' Please add ETH to your wallet to cover transaction fees.';
+    
+    if (requiredGasFee != null) {
+      final requiredEth = (requiredGasFee / BigInt.from(10).pow(18)).toStringAsFixed(8);
+      final balanceInfo = currentBalance != null 
+          ? ', Available: ${(currentBalance / BigInt.from(10).pow(18)).toStringAsFixed(8)} ETH'
+          : '';
+      return '$baseMessage Required: ~$requiredEth ETH$balanceInfo.$addEthMessage';
+    }
+    
+    return '$baseMessage$addEthMessage';
+  }
+
+  @override
+  String toString() => exceptionMessage;
+}

lib/src/screens/integrations/deuro/savings_page.dart

@@ -4,9 +4,11 @@ import 'package:cake_wallet/src/screens/base_page.dart';
 import 'package:cake_wallet/src/screens/integrations/deuro/widgets/interest_card_widget.dart';
 import 'package:cake_wallet/src/screens/integrations/deuro/widgets/savings_card_widget.dart';
 import 'package:cake_wallet/src/screens/integrations/deuro/widgets/savings_edit_sheet.dart';
+import 'package:cake_wallet/src/widgets/alert_with_one_action.dart';
 import 'package:cake_wallet/src/widgets/bottom_sheet/confirm_sending_bottom_sheet_widget.dart';
 import 'package:cake_wallet/src/widgets/bottom_sheet/info_bottom_sheet_widget.dart';
 import 'package:cake_wallet/src/widgets/gradient_background.dart';
+import 'package:cake_wallet/utils/show_pop_up.dart';
 import 'package:cake_wallet/view_model/integrations/deuro_view_model.dart';
 import 'package:cake_wallet/view_model/send/send_view_model_state.dart';
 import 'package:cw_core/crypto_currency.dart';
@@ -190,6 +192,24 @@ class DEuroSavingsPage extends BasePage {
           );
         });
       }
+
+      if (state is FailureState) {
+        WidgetsBinding.instance.addPostFrameCallback((_) async {
+          if (!context.mounted) return;
+
+          await showPopUp<void>(
+            context: context,
+            builder: (BuildContext popupContext) {
+              return AlertWithOneAction(
+                alertTitle: S.of(popupContext).error,
+                alertContent: state.error,
+                buttonText: S.of(popupContext).ok,
+                buttonAction: () => Navigator.of(popupContext).pop(),
+              );
+            },
+          );
+        });
+      }
     });
 
     _isReactionsSet = true;

lib/view_model/integrations/deuro_view_model.dart

@@ -46,10 +46,8 @@ abstract class DEuroViewModelBase with Store {
 
   @action
   Future<void> reloadSavingsUserData() async {
-    final savingsBalanceRaw =
-    ethereum!.getDEuroSavingsBalance(_appStore.wallet!);
-    final accruedInterestRaw =
-    ethereum!.getDEuroAccruedInterest(_appStore.wallet!);
+    final savingsBalanceRaw = ethereum!.getDEuroSavingsBalance(_appStore.wallet!);
+    final accruedInterestRaw = ethereum!.getDEuroAccruedInterest(_appStore.wallet!);
 
     approvedTokens = await ethereum!.getDEuroSavingsApproved(_appStore.wallet!);
 
@@ -63,56 +61,73 @@ abstract class DEuroViewModelBase with Store {
 
   @action
   Future<void> reloadInterestRate() async {
-    final interestRateRaw =
-    await ethereum!.getDEuroInterestRate(_appStore.wallet!);
+    final interestRateRaw = await ethereum!.getDEuroInterestRate(_appStore.wallet!);
 
     interestRate = (interestRateRaw / BigInt.from(10000)).toString();
   }
 
   @action
   Future<void> prepareApproval() async {
-    final priority = _appStore.settingsStore.priority[WalletType.ethereum]!;
-    approvalTransaction =
-        await ethereum!.enableDEuroSaving(_appStore.wallet!, priority);
+    try {
+      state = TransactionCommitting();
+      final priority = _appStore.settingsStore.priority[WalletType.ethereum]!;
+      approvalTransaction = await ethereum!.enableDEuroSaving(_appStore.wallet!, priority);
+      state = InitialExecutionState();
+    } catch (e) {
+      state = FailureState(e.toString());
+    }
   }
 
   @action
   Future<void> prepareSavingsEdit(String amountRaw, bool isAdding) async {
-    final amount = BigInt.from(num.parse(amountRaw) * pow(10, 18));
-    final priority = _appStore.settingsStore.priority[WalletType.ethereum]!;
-    transaction = await (isAdding
-        ? ethereum!.addDEuroSaving(_appStore.wallet!, amount, priority)
-        : ethereum!.removeDEuroSaving(_appStore.wallet!, amount, priority));
+    try {
+      state = TransactionCommitting();
+      final amount = BigInt.from(num.parse(amountRaw) * pow(10, 18));
+      final priority = _appStore.settingsStore.priority[WalletType.ethereum]!;
+      transaction = await (isAdding
+          ? ethereum!.addDEuroSaving(_appStore.wallet!, amount, priority)
+          : ethereum!.removeDEuroSaving(_appStore.wallet!, amount, priority));
+      state = InitialExecutionState();
+    } catch (e) {
+      state = FailureState(e.toString());
+    }
   }
 
-  Future<void> prepareCollectInterest() =>
-      prepareSavingsEdit(accruedInterest, false);
+  Future<void> prepareCollectInterest() => prepareSavingsEdit(accruedInterest, false);
 
   @action
   Future<void> commitTransaction() async {
     if (transaction != null) {
-      state = TransactionCommitting();
-      await transaction!.commit();
-      transaction = null;
-      reloadSavingsUserData();
-      state = TransactionCommitted();
+      try {
+        state = TransactionCommitting();
+        await transaction!.commit();
+        transaction = null;
+        reloadSavingsUserData();
+        state = TransactionCommitted();
+      } catch (e) {
+        state = FailureState(e.toString());
+      }
     }
   }
 
   @action
   Future<void> commitApprovalTransaction() async {
     if (approvalTransaction != null) {
-      state = TransactionCommitting();
-      await approvalTransaction!.commit();
-      approvalTransaction = null;
-      reloadSavingsUserData();
-      state = TransactionCommitted();
+      try {
+        state = TransactionCommitting();
+        await approvalTransaction!.commit();
+        approvalTransaction = null;
+        reloadSavingsUserData();
+        state = TransactionCommitted();
+      } catch (e) {
+        state = FailureState(e.toString());
+      }
     }
   }
 
   @action
   void dismissTransaction() {
-    transaction == null;
+    transaction = null;
     approvalTransaction = null;
     state = InitialExecutionState();
   }