package keeper import ( errorsmod "cosmossdk.io/errors" sdk "github.com/cosmos/cosmos-sdk/types" "github.com/kava-labs/kava/x/hard/types" ) // Repay borrowed funds func (k Keeper) Repay(ctx sdk.Context, sender, owner sdk.AccAddress, coins sdk.Coins) error { // Check borrow exists here to avoid duplicating store read in ValidateRepay borrow, found := k.GetBorrow(ctx, owner) if !found { return types.ErrBorrowNotFound } // Call incentive hook k.BeforeBorrowModified(ctx, borrow) // Sync borrow interest so loan is up-to-date k.SyncBorrowInterest(ctx, owner) // Refresh borrow after syncing interest borrow, _ = k.GetBorrow(ctx, owner) // cap the repayment by what's available to repay (the borrow amount) payment, err := k.CalculatePaymentAmount(borrow.Amount, coins) if err != nil { return err } // Validate that sender holds coins for repayment err = k.ValidateRepay(ctx, sender, owner, payment) if err != nil { return err } // Sends coins from user to Hard module account err = k.bankKeeper.SendCoinsFromAccountToModule(ctx, sender, types.ModuleAccountName, payment) if err != nil { return err } // If any coin denoms have been completely repaid reset the denom's borrow index factor for _, coin := range payment { if coin.Amount.Equal(borrow.Amount.AmountOf(coin.Denom)) { borrowIndex, removed := borrow.Index.RemoveInterestFactor(coin.Denom) if !removed { return errorsmod.Wrapf(types.ErrInvalidIndexFactorDenom, "%s", coin.Denom) } borrow.Index = borrowIndex } } // Update user's borrow in store borrow.Amount = borrow.Amount.Sub(payment...) if borrow.Amount.Empty() { k.DeleteBorrow(ctx, borrow) } else { k.SetBorrow(ctx, borrow) } // Update total borrowed amount err = k.DecrementBorrowedCoins(ctx, payment) if err != nil { return err } // Call incentive hook k.AfterBorrowModified(ctx, borrow) ctx.EventManager().EmitEvent( sdk.NewEvent( types.EventTypeHardRepay, sdk.NewAttribute(types.AttributeKeySender, sender.String()), sdk.NewAttribute(types.AttributeKeyOwner, owner.String()), sdk.NewAttribute(types.AttributeKeyRepayCoins, payment.String()), ), ) return nil } // ValidateRepay validates a requested loan repay func (k Keeper) ValidateRepay(ctx sdk.Context, sender, owner sdk.AccAddress, coins sdk.Coins) error { assetPriceCache := map[string]sdk.Dec{} // Get the total USD value of user's existing borrows existingBorrowUSDValue := sdk.ZeroDec() existingBorrow, found := k.GetBorrow(ctx, owner) if found { for _, coin := range existingBorrow.Amount { moneyMarket, found := k.GetMoneyMarket(ctx, coin.Denom) if !found { return errorsmod.Wrapf(types.ErrMarketNotFound, "no money market found for denom %s", coin.Denom) } assetPrice, ok := assetPriceCache[coin.Denom] if !ok { // Fetch current asset price and store in local cache assetPriceInfo, err := k.pricefeedKeeper.GetCurrentPrice(ctx, moneyMarket.SpotMarketID) if err != nil { return errorsmod.Wrapf(types.ErrPriceNotFound, "no price found for market %s", moneyMarket.SpotMarketID) } assetPriceCache[coin.Denom] = assetPriceInfo.Price assetPrice = assetPriceInfo.Price } // Calculate this borrow coin's USD value and add it to the total previous borrowed USD value coinUSDValue := sdk.NewDecFromInt(coin.Amount).Quo(sdk.NewDecFromInt(moneyMarket.ConversionFactor)).Mul(assetPrice) existingBorrowUSDValue = existingBorrowUSDValue.Add(coinUSDValue) } } senderCoins := k.bankKeeper.SpendableCoins(ctx, sender) repayTotalUSDValue := sdk.ZeroDec() for _, repayCoin := range coins { // Check that sender holds enough tokens to make the proposed payment if senderCoins.AmountOf(repayCoin.Denom).LT(repayCoin.Amount) { return errorsmod.Wrapf(types.ErrInsufficientBalanceForRepay, "account can only repay up to %s%s", senderCoins.AmountOf(repayCoin.Denom), repayCoin.Denom) } moneyMarket, found := k.GetMoneyMarket(ctx, repayCoin.Denom) if !found { return errorsmod.Wrapf(types.ErrMarketNotFound, "no money market found for denom %s", repayCoin.Denom) } // Calculate this coin's USD value and add it to the repay's total USD value assetPrice, ok := assetPriceCache[repayCoin.Denom] if !ok { // Fetch current asset price and store in local cache assetPriceInfo, err := k.pricefeedKeeper.GetCurrentPrice(ctx, moneyMarket.SpotMarketID) if err != nil { return errorsmod.Wrapf(types.ErrPriceNotFound, "no price found for market %s", moneyMarket.SpotMarketID) } assetPriceCache[repayCoin.Denom] = assetPriceInfo.Price assetPrice = assetPriceInfo.Price } coinUSDValue := sdk.NewDecFromInt(repayCoin.Amount).Quo(sdk.NewDecFromInt(moneyMarket.ConversionFactor)).Mul(assetPrice) repayTotalUSDValue = repayTotalUSDValue.Add(coinUSDValue) } // If the proposed repayment would results in a borrowed USD value below the minimum borrow USD value, reject it. // User can overpay their loan to close it out, but underpaying by such a margin that the USD value is in an // invalid range is not allowed // Unless the user is fully repaying their loan proposedBorrowNewUSDValue := existingBorrowUSDValue.Sub(repayTotalUSDValue) isFullRepayment := coins.IsEqual(existingBorrow.Amount) if proposedBorrowNewUSDValue.LT(k.GetMinimumBorrowUSDValue(ctx)) && !isFullRepayment { return errorsmod.Wrapf(types.ErrBelowMinimumBorrowValue, "the proposed borrow's USD value $%s is below the minimum borrow limit $%s", proposedBorrowNewUSDValue, k.GetMinimumBorrowUSDValue(ctx)) } return nil } // CalculatePaymentAmount prevents overpayment when repaying borrowed coins func (k Keeper) CalculatePaymentAmount(owed sdk.Coins, payment sdk.Coins) (sdk.Coins, error) { repayment := sdk.Coins{} if !payment.DenomsSubsetOf(owed) { return repayment, types.ErrInvalidRepaymentDenom } for _, coin := range payment { if coin.Amount.GT(owed.AmountOf(coin.Denom)) { repayment = append(repayment, sdk.NewCoin(coin.Denom, owed.AmountOf(coin.Denom))) } else { repayment = append(repayment, coin) } } return repayment, nil }