import EVM from 0xe467b9dd11fa00df import FlowToken from 0x1654653399040a61 import FungibleToken from 0xf233dcee88fe0abe import FlowEVMBridgeConfig from 0x1e4aa0b87d10b141 import FlowEVMBridgeUtils from 0x1e4aa0b87d10b141 import ScopedFTProviders from 0x1e4aa0b87d10b141 access(all) contract FlowEVMUtil { access(all) fun approveAndSwap(_ coa: auth(EVM.Call) &EVM.CadenceOwnedAccount, tokenAddress: EVM.EVMAddress, amount: UInt256, contractAddress: EVM.EVMAddress, txdata: [UInt8], gasLimit: UInt64): [UInt8] { self.approveERC20(coa, tokenAddress: tokenAddress, spenderAddress: contractAddress, amount: amount) return self.runCall(coa, contractAddress: contractAddress, txdata: txdata, gasLimit: gasLimit, value: EVM.Balance(attoflow: 0)) } access(all) fun runCall(_ coa: auth(EVM.Call) &EVM.CadenceOwnedAccount, contractAddress: EVM.EVMAddress, txdata: [UInt8], gasLimit: UInt64, value: EVM.Balance): [UInt8] { let runResult = coa.call(to: contractAddress, data: txdata, gasLimit: gasLimit, value: value) assert(runResult.status == EVM.Status.successful, message: "tx failed. ".concat(self.formatResultError(runResult))) return runResult.data } access(all) fun approveERC20(_ coa: auth(EVM.Call) &EVM.CadenceOwnedAccount, tokenAddress: EVM.EVMAddress, spenderAddress: EVM.EVMAddress, amount: UInt256) { let runResult = coa.call(to: tokenAddress, data: EVM.encodeABIWithSignature("approve(address,uint256)", [spenderAddress, amount]), gasLimit: 60_000, value: EVM.Balance(attoflow: 0)) assert(runResult.status == EVM.Status.successful, message: "approve failed. ".concat(self.formatResultError(runResult))) } access(all) fun balanceOf(_ coa: auth(EVM.Call) &EVM.CadenceOwnedAccount, tokenAddress: EVM.EVMAddress, address: EVM.EVMAddress): UInt256 { let runResult = coa.call(to: tokenAddress, data: EVM.encodeABIWithSignature("balanceOf(address)", [address]), gasLimit: 35_000, value: EVM.Balance(attoflow: 0)) assert(runResult.status == EVM.Status.successful, message: "balanceOf failed. ".concat(FlowEVMUtil.formatResultError(runResult))) return FlowEVMUtil.convertBytesToUInt256(runResult.data) } access(all) fun convertToAttoFLOW(_ value: UFix64): UInt256 { let converted = EVM.Balance(attoflow: 0) converted.setFLOW(flow: value) return UInt256(converted.inAttoFLOW()) } access(all) fun convertBytesToUInt256(_ bytes: [UInt8]): UInt256 { var value: UInt256 = 0 for byte in bytes { value = (value << 8) | UInt256(byte) } return value } access(all) fun roundForCadence(_ value: UInt256, _ tokenAddr: EVM.EVMAddress): UInt256 { let ufixedAmount = FlowEVMBridgeUtils.convertERC20AmountToCadenceAmount(value, erc20Address: tokenAddr) return FlowEVMBridgeUtils.convertCadenceAmountToERC20Amount(ufixedAmount, erc20Address: tokenAddr) } access(all) fun formatResultError(_ callResult: EVM.Result): String { if callResult.status == EVM.Status.successful { return "success" } var status = "failed" if callResult.status == EVM.Status.invalid { status = "invalid" } else if callResult.status == EVM.Status.unknown { status = "unknown" } return "status: ".concat(status).concat(" [").concat(callResult.errorCode.toString()).concat("]: ").concat(callResult.errorMessage) } access(all) fun bridgeTokenToEVM(_ coa: auth(EVM.Bridge) &EVM.CadenceOwnedAccount, capCopy: Capability, vault: @{FungibleToken.Vault}): UInt256 { let tokenAddr = FlowEVMBridgeConfig.getEVMAddressAssociated(with: vault.getType())! let evmAmount = FlowEVMBridgeUtils.convertCadenceAmountToERC20Amount(vault.balance, erc20Address: tokenAddr) let scopedProvider <- ScopedFTProviders.createScopedFTProvider( provider: capCopy, filters: [ ScopedFTProviders.AllowanceFilter(FlowEVMBridgeUtils.calculateBridgeFee(bytes: 0)) ], expiration: getCurrentBlock().timestamp + 1.0 ) coa.depositTokens( vault: <-vault, feeProvider: &scopedProvider as auth(FungibleToken.Withdraw) &{FungibleToken.Provider} ) destroy scopedProvider return evmAmount } access(all) fun bridgeTokenToCadence(_ coa: auth(EVM.Bridge) &EVM.CadenceOwnedAccount, capCopy: Capability, vaultType: Type, amount: UInt256): @{FungibleToken.Vault} { let scopedProvider <- ScopedFTProviders.createScopedFTProvider( provider: capCopy, filters: [ ScopedFTProviders.AllowanceFilter(FlowEVMBridgeUtils.calculateBridgeFee(bytes: 0)) ], expiration: getCurrentBlock().timestamp + 1.0 ) let bridgedVault: @{FungibleToken.Vault} <- coa.withdrawTokens( type: vaultType, amount: amount, feeProvider: &scopedProvider as auth(FungibleToken.Withdraw) &{FungibleToken.Provider} ) destroy scopedProvider return <-bridgedVault } access(all) fun bridgeFlowToCadence(_ coa: auth(EVM.Withdraw) &EVM.CadenceOwnedAccount, amount: UInt256): @FlowToken.Vault { let rounded = self.roundForCadence(amount, EVM.addressFromString("0xd3bF53DAC106A0290B0483EcBC89d40FcC961f3e")) return <- coa.withdraw(balance: EVM.Balance(attoflow: UInt(rounded))) } }

Contract