package keeper import ( "fmt" sdk "github.com/cosmos/cosmos-sdk/types" sdkerrors "github.com/cosmos/cosmos-sdk/types/errors" evmtypes "github.com/evmos/ethermint/x/evm/types" "github.com/kava-labs/kava/x/evmutil/types" ) const ( // EvmDenom is the gas denom used by the evm EvmDenom = "akava" // CosmosDenom is the gas denom used by the kava app CosmosDenom = "ukava" ) // ConversionMultiplier is the conversion multiplier between akava and ukava var ConversionMultiplier = sdk.NewInt(1_000_000_000_000) var _ evmtypes.BankKeeper = EvmBankKeeper{} // EvmBankKeeper is a BankKeeper wrapper for the x/evm module to allow the use // of the 18 decimal akava coin on the evm. // x/evm consumes gas and send coins by minting and burning akava coins in its module // account and then sending the funds to the target account. // This keeper uses both the ukava coin and a separate akava balance to manage the // extra percision needed by the evm. type EvmBankKeeper struct { akavaKeeper Keeper bk types.BankKeeper ak types.AccountKeeper } func NewEvmBankKeeper(akavaKeeper Keeper, bk types.BankKeeper, ak types.AccountKeeper) EvmBankKeeper { return EvmBankKeeper{ akavaKeeper: akavaKeeper, bk: bk, ak: ak, } } // GetBalance returns the total **spendable** balance of akava for a given account by address. func (k EvmBankKeeper) GetBalance(ctx sdk.Context, addr sdk.AccAddress, denom string) sdk.Coin { if denom != EvmDenom { panic(fmt.Errorf("only evm denom %s is supported by EvmBankKeeper", EvmDenom)) } spendableCoins := k.bk.SpendableCoins(ctx, addr) ukava := spendableCoins.AmountOf(CosmosDenom) akava := k.akavaKeeper.GetBalance(ctx, addr) total := ukava.Mul(ConversionMultiplier).Add(akava) return sdk.NewCoin(EvmDenom, total) } // SendCoins transfers akava coins from a AccAddress to an AccAddress. func (k EvmBankKeeper) SendCoins(ctx sdk.Context, senderAddr sdk.AccAddress, recipientAddr sdk.AccAddress, amt sdk.Coins) error { // SendCoins method is not used by the evm module, but is required by the // evmtypes.BankKeeper interface. This must be updated if the evm module // is updated to use SendCoins. panic("not implemented") } // SendCoinsFromModuleToAccount transfers akava coins from a ModuleAccount to an AccAddress. // It will panic if the module account does not exist. An error is returned if the recipient // address is black-listed or if sending the tokens fails. func (k EvmBankKeeper) SendCoinsFromModuleToAccount(ctx sdk.Context, senderModule string, recipientAddr sdk.AccAddress, amt sdk.Coins) error { ukava, akava, err := SplitAkavaCoins(amt) if err != nil { return err } if ukava.Amount.IsPositive() { if err := k.bk.SendCoinsFromModuleToAccount(ctx, senderModule, recipientAddr, sdk.NewCoins(ukava)); err != nil { return err } } senderAddr := k.GetModuleAddress(senderModule) if err := k.ConvertOneUkavaToAkavaIfNeeded(ctx, senderAddr, akava); err != nil { return err } if err := k.akavaKeeper.SendBalance(ctx, senderAddr, recipientAddr, akava); err != nil { return err } return k.ConvertAkavaToUkava(ctx, recipientAddr) } // SendCoinsFromAccountToModule transfers akava coins from an AccAddress to a ModuleAccount. // It will panic if the module account does not exist. func (k EvmBankKeeper) SendCoinsFromAccountToModule(ctx sdk.Context, senderAddr sdk.AccAddress, recipientModule string, amt sdk.Coins) error { ukava, akavaNeeded, err := SplitAkavaCoins(amt) if err != nil { return err } if ukava.IsPositive() { if err := k.bk.SendCoinsFromAccountToModule(ctx, senderAddr, recipientModule, sdk.NewCoins(ukava)); err != nil { return err } } if err := k.ConvertOneUkavaToAkavaIfNeeded(ctx, senderAddr, akavaNeeded); err != nil { return err } recipientAddr := k.GetModuleAddress(recipientModule) if err := k.akavaKeeper.SendBalance(ctx, senderAddr, recipientAddr, akavaNeeded); err != nil { return err } return k.ConvertAkavaToUkava(ctx, recipientAddr) } // MintCoins mints akava coins by minting the equivalent ukava coins and any remaining akava coins. // It will panic if the module account does not exist or is unauthorized. func (k EvmBankKeeper) MintCoins(ctx sdk.Context, moduleName string, amt sdk.Coins) error { ukava, akava, err := SplitAkavaCoins(amt) if err != nil { return err } if ukava.IsPositive() { if err := k.bk.MintCoins(ctx, moduleName, sdk.NewCoins(ukava)); err != nil { return err } } recipientAddr := k.GetModuleAddress(moduleName) if err := k.akavaKeeper.AddBalance(ctx, recipientAddr, akava); err != nil { return err } return k.ConvertAkavaToUkava(ctx, recipientAddr) } // BurnCoins burns akava coins by burning the equivalent ukava coins and any remaining akava coins. // It will panic if the module account does not exist or is unauthorized. func (k EvmBankKeeper) BurnCoins(ctx sdk.Context, moduleName string, amt sdk.Coins) error { ukava, akava, err := SplitAkavaCoins(amt) if err != nil { return err } if ukava.IsPositive() { if err := k.bk.BurnCoins(ctx, moduleName, sdk.NewCoins(ukava)); err != nil { return err } } moduleAddr := k.GetModuleAddress(moduleName) if err := k.ConvertOneUkavaToAkavaIfNeeded(ctx, moduleAddr, akava); err != nil { return err } return k.akavaKeeper.RemoveBalance(ctx, moduleAddr, akava) } // ConvertOneUkavaToAkavaIfNeeded converts 1 ukava to akava for an address if // its akava balance is smaller than the akavaNeeded amount. func (k EvmBankKeeper) ConvertOneUkavaToAkavaIfNeeded(ctx sdk.Context, addr sdk.AccAddress, akavaNeeded sdk.Int) error { akavaBal := k.akavaKeeper.GetBalance(ctx, addr) if akavaBal.GTE(akavaNeeded) { return nil } ukavaToStore := sdk.NewCoins(sdk.NewCoin(CosmosDenom, sdk.OneInt())) if err := k.bk.SendCoinsFromAccountToModule(ctx, addr, types.ModuleName, ukavaToStore); err != nil { return err } // add 1ukava equivalent of akava to addr akavaToReceive := ConversionMultiplier if err := k.akavaKeeper.AddBalance(ctx, addr, akavaToReceive); err != nil { return err } return nil } // ConvertAkavaToUkava converts all available akava to ukava for a given AccAddress. func (k EvmBankKeeper) ConvertAkavaToUkava(ctx sdk.Context, addr sdk.AccAddress) error { totalAkava := k.akavaKeeper.GetBalance(ctx, addr) ukava, _, err := SplitAkavaCoins(sdk.NewCoins(sdk.NewCoin(EvmDenom, totalAkava))) if err != nil { return err } // do nothing if account does not have enough akava for a single ukava ukavaToReceive := ukava.Amount if !ukavaToReceive.IsPositive() { return nil } // remove akava used for converting to ukava akavaToBurn := ukavaToReceive.Mul(ConversionMultiplier) finalBal := totalAkava.Sub(akavaToBurn) if err := k.akavaKeeper.SetBalance(ctx, addr, finalBal); err != nil { return err } fromAddr := k.GetModuleAddress(types.ModuleName) if err := k.bk.SendCoins(ctx, fromAddr, addr, sdk.NewCoins(ukava)); err != nil { return err } return nil } func (k EvmBankKeeper) GetModuleAddress(moduleName string) sdk.AccAddress { addr := k.ak.GetModuleAddress(moduleName) if addr == nil { panic(sdkerrors.Wrapf(sdkerrors.ErrUnknownAddress, "module account %s does not exist", moduleName)) } return addr } // SplitAkavaCoins splits akava coins to the equivalent ukava coins and any remaining akava balance. // An error will be returned if the coins are not valid or if the coins are not the akava denom. func SplitAkavaCoins(coins sdk.Coins) (sdk.Coin, sdk.Int, error) { akava := sdk.ZeroInt() ukava := sdk.NewCoin(CosmosDenom, sdk.ZeroInt()) if len(coins) == 0 { return ukava, akava, nil } if err := ValidateEvmCoins(coins); err != nil { return ukava, akava, err } // note: we should always have len(coins) == 1 here since coins cannot have dup denoms after we validate. coin := coins[0] remainingBalance := coin.Amount.Mod(ConversionMultiplier) if remainingBalance.IsPositive() { akava = remainingBalance } ukavaAmount := coin.Amount.Quo(ConversionMultiplier) if ukavaAmount.IsPositive() { ukava = sdk.NewCoin(CosmosDenom, ukavaAmount) } return ukava, akava, nil } // ValidateEvmCoins validates the coins from evm is valid and is the EvmDenom (akava). func ValidateEvmCoins(coins sdk.Coins) error { if len(coins) == 0 { return nil } // validate that coins are non-negative, sorted, and no dup denoms if err := coins.Validate(); err != nil { return sdkerrors.Wrap(sdkerrors.ErrInvalidCoins, coins.String()) } // validate that coin denom is akava if len(coins) != 1 || coins[0].Denom != EvmDenom { errMsg := fmt.Sprintf("invalid evm coin denom, only %s is supported", EvmDenom) return sdkerrors.Wrap(sdkerrors.ErrInvalidCoins, errMsg) } return nil }