CW-1069-implement-deuro-dapp-support (#2304)

* feat: started dEuro Savings integration

* fix: merge conflict regarding theming

* feat: Add dEuro Savings Screen

* feat: Change DEuro Savings UI

* feat: Complete DEuro Savings integration with UI enhancements and transaction support

* style: remove forgotten print statements

* feat: localize dEuro subtitle

* feat: add approval flow and priority handling to DEuro Savings integration

- Introduced approval flow for DEuro Savings to enable token approvals.
- Added priority handling for deposit and withdrawal operations.
- Updated UI to support approval state and interactions.
- Localized new strings for multiple languages.
- Enhanced transaction handling with separate approval and commit actions.

* feat: add support for ERC20 token approval transactions

- Introduced `signApprovalTransaction` and `createApprovalTransaction` methods.
- Added handling for infinite approvals.
- Implemented encoding for approval transaction data.
- Enhanced transaction creation flow with approval-specific functionality.

* Update UI

* feat: enhance DEuro Savings logic and UI with computed property and fix gradient background

* feat: localize transaction confirmation content for DEuro Savings

* feat: enable interest collection for DEuro Savings with localized support

* fix reformatting [skip ci]

---------

Co-authored-by: tuxsudo <tuxsudo@tux.pizza>
Co-authored-by: OmarHatem <omarh.ismail1@gmail.com>

cw_ethereum/lib/deuro/deuro_savings.dart

@@ -0,0 +1,121 @@
+import 'dart:convert';
+import 'dart:typed_data';
+
+import 'package:crypto/crypto.dart';
+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_transaction_priority.dart';
+import 'package:cw_evm/pending_evm_chain_transaction.dart';
+import 'package:web3dart/web3dart.dart';
+
+const String savingsGatewayAddress =
+    "0x073493d73258C4BEb6542e8dd3e1b2891C972303";
+
+const String dEuroAddress = "0xbA3f535bbCcCcA2A154b573Ca6c5A49BAAE0a3ea";
+
+class DEuro {
+  final SavingsGateway _savingsGateway;
+  final ERC20 _dEuro;
+  final EthereumWallet _wallet;
+
+  DEuro(EthereumWallet wallet)
+      : _wallet = wallet,
+        _savingsGateway = _getSavingsGateway(wallet.getWeb3Client()!),
+        _dEuro = _getDEuroToken(wallet.getWeb3Client()!);
+
+  static SavingsGateway _getSavingsGateway(Web3Client client) => SavingsGateway(
+        address: EthereumAddress.fromHex(savingsGatewayAddress),
+        client: client,
+      );
+
+  static ERC20 _getDEuroToken(Web3Client client) => ERC20(
+        address: EthereumAddress.fromHex(dEuroAddress),
+        client: client,
+      );
+
+  final frontendCode =
+      Uint8List.fromList(sha256.convert(utf8.encode("wallet")).bytes);
+
+  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 interestRate => _savingsGateway.currentRatePPM();
+
+  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,
+    );
+
+    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);
+  }
+
+  Future<PendingEVMChainTransaction> withdrawSavings(
+      BigInt amount, EVMChainTransactionPriority priority) async {
+    final signedTransaction = await _savingsGateway.withdraw(
+      (target: _address, 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);
+  }
+
+  // Set an infinite approval to save gas in the future
+  Future<PendingEVMChainTransaction> enableSavings(
+          EVMChainTransactionPriority priority) async =>
+      (await _wallet.createApprovalTransaction(
+        BigInt.parse(
+          'ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff',
+          radix: 16,
+        ),
+        _savingsGateway.self.address.hexEip55,
+        CryptoCurrency.deuro,
+        priority,
+      )) as PendingEVMChainTransaction;
+}

cw_ethereum/pubspec.yaml

@@ -6,7 +6,7 @@ author: Cake Wallet
 homepage: https://cakewallet.com
 
 environment:
-  sdk: '>=2.18.2 <3.0.0'
+  sdk: ^3.5.0
   flutter: ">=1.17.0"
 
 dependencies: