import FungibleToken from 0xf233dcee88fe0abe import FungibleTokenMetadataViews from 0xf233dcee88fe0abe import ViewResolver from 0x1d7e57aa55817448 import MetadataViews from 0x1d7e57aa55817448 import FlowToken from 0x1654653399040a61 import ScopedFTProviders from 0x1e4aa0b87d10b141 import EVM from 0xe467b9dd11fa00df import FlowEVMBridge from 0x1e4aa0b87d10b141 import FlowEVMBridgeConfig from 0x1e4aa0b87d10b141 import FlowEVMBridgeUtils from 0x1e4aa0b87d10b141 /// This transaction bridges fungible tokens from EVM to Cadence assuming it has already been onboarded to the /// FlowEVMBridge. /// /// NOTE: The ERC721 must have first been onboarded to the bridge. This can be checked via the method /// FlowEVMBridge.evmAddressRequiresOnboarding(address: self.evmContractAddress) /// /// @param tokenContractAddress: The Flow account address hosting the FT-defining Cadence contract /// @param tokenContractName: The name of the Vault-defining Cadence contract /// @param amount: The amount of tokens to bridge from EVM /// transaction(tokenContractAddress: Address, tokenContractName: String, amount: UInt256) { let vaultType: Type let receiver: &{FungibleToken.Vault} let scopedProvider: @ScopedFTProviders.ScopedFTProvider let coa: auth(EVM.Bridge) &EVM.CadenceOwnedAccount prepare(signer: auth(BorrowValue, CopyValue, IssueStorageCapabilityController, PublishCapability, SaveValue, UnpublishCapability) &Account) { /* --- Reference the signer's CadenceOwnedAccount --- */ // // Borrow a reference to the signer's COA self.coa = signer.storage.borrow(from: /storage/evm) ?? panic("Could not borrow COA from provided gateway address") // Get the ERC20 contract address for the given FungibleToken Vault type self.vaultType = FlowEVMBridgeUtils.buildCompositeType( address: tokenContractAddress, contractName: tokenContractName, resourceName: "Vault" ) ?? panic("Could not construct Vault type of: " .concat(tokenContractAddress.toString()).concat(".").concat(tokenContractName).concat(".Vault")) /* --- Reference the signer's Vault --- */ // // Borrow a reference to the FungibleToken Vault, configuring if necessary let viewResolver = getAccount(tokenContractAddress).contracts.borrow<&{ViewResolver}>(name: tokenContractName) ?? panic("Could not borrow ViewResolver from FungibleToken contract") let vaultData = viewResolver.resolveContractView( resourceType: self.vaultType, viewType: Type() ) as! FungibleTokenMetadataViews.FTVaultData? ?? panic("Could not resolve FTVaultData view") // If the vault does not exist, create it and publish according to the contract's defined configuration if signer.storage.borrow<&{FungibleToken.Vault}>(from: vaultData.storagePath) == nil { signer.storage.save(<-vaultData.createEmptyVault(), to: vaultData.storagePath) signer.capabilities.unpublish(vaultData.receiverPath) signer.capabilities.unpublish(vaultData.metadataPath) let receiverCap = signer.capabilities.storage.issue<&{FungibleToken.Vault}>(vaultData.storagePath) let metadataCap = signer.capabilities.storage.issue<&{FungibleToken.Vault}>(vaultData.storagePath) signer.capabilities.publish(receiverCap, at: vaultData.receiverPath) signer.capabilities.publish(metadataCap, at: vaultData.metadataPath) } self.receiver = signer.storage.borrow<&{FungibleToken.Vault}>(from: vaultData.storagePath) ?? panic("Could not borrow Vault from storage path") /* --- Configure a ScopedFTProvider --- */ // // Calculate the bridge fee - bridging from EVM consumes no storage, so flat fee let approxFee = FlowEVMBridgeUtils.calculateBridgeFee(bytes: 0) // Issue and store bridge-dedicated Provider Capability in storage if necessary if signer.storage.type(at: FlowEVMBridgeConfig.providerCapabilityStoragePath) == nil { let providerCap = signer.capabilities.storage.issue( /storage/flowTokenVault ) signer.storage.save(providerCap, to: FlowEVMBridgeConfig.providerCapabilityStoragePath) } // Copy the stored Provider capability and create a ScopedFTProvider let providerCapCopy = signer.storage.copy>( from: FlowEVMBridgeConfig.providerCapabilityStoragePath ) ?? panic("Invalid Provider Capability found in storage.") let providerFilter = ScopedFTProviders.AllowanceFilter(approxFee) self.scopedProvider <- ScopedFTProviders.createScopedFTProvider( provider: providerCapCopy, filters: [ providerFilter ], expiration: getCurrentBlock().timestamp + 1.0 ) } execute { // Execute the bridge request let vault: @{FungibleToken.Vault} <- self.coa.withdrawTokens( type: self.vaultType, amount: amount, feeProvider: &self.scopedProvider as auth(FungibleToken.Withdraw) &{FungibleToken.Provider} ) // Deposit the bridged token into the signer's vault self.receiver.deposit(from: <-vault) // Destroy the ScopedFTProvider destroy self.scopedProvider } }

Transaction