package keeper import ( "fmt" sdk "github.com/cosmos/cosmos-sdk/types" sdkerrors "github.com/cosmos/cosmos-sdk/types/errors" "github.com/kava-labs/kava/x/cdp/types" ) // AddPrincipal adds debt to a cdp if the additional debt does not put the cdp below the liquidation ratio func (k Keeper) AddPrincipal(ctx sdk.Context, owner sdk.AccAddress, denom string, principal sdk.Coin) error { // validation cdp, found := k.GetCdpByOwnerAndDenom(ctx, owner, denom) if !found { return sdkerrors.Wrapf(types.ErrCdpNotFound, "owner %s, denom %s", owner, denom) } err := k.ValidatePrincipalDraw(ctx, principal, cdp.Principal.Denom) if err != nil { return err } err = k.ValidateDebtLimit(ctx, cdp.Collateral.Denom, principal) if err != nil { return err } err = k.ValidateCollateralizationRatio(ctx, cdp.Collateral, cdp.Principal.Add(principal), cdp.AccumulatedFees) if err != nil { return err } // mint the principal and send it to the cdp owner err = k.supplyKeeper.MintCoins(ctx, types.ModuleName, sdk.NewCoins(principal)) if err != nil { panic(err) } err = k.supplyKeeper.SendCoinsFromModuleToAccount(ctx, types.ModuleName, owner, sdk.NewCoins(principal)) if err != nil { panic(err) } // mint the corresponding amount of debt coins in the cdp module account err = k.MintDebtCoins(ctx, types.ModuleName, k.GetDebtDenom(ctx), principal) if err != nil { panic(err) } // emit cdp draw event ctx.EventManager().EmitEvent( sdk.NewEvent( types.EventTypeCdpDraw, sdk.NewAttribute(sdk.AttributeKeyAmount, principal.String()), sdk.NewAttribute(types.AttributeKeyCdpID, fmt.Sprintf("%d", cdp.ID)), ), ) // remove old collateral:debt index oldCollateralToDebtRatio := k.CalculateCollateralToDebtRatio(ctx, cdp.Collateral, cdp.Principal.Add(cdp.AccumulatedFees)) k.RemoveCdpCollateralRatioIndex(ctx, denom, cdp.ID, oldCollateralToDebtRatio) // update cdp state cdp.Principal = cdp.Principal.Add(principal) // increment total principal for the input collateral type k.IncrementTotalPrincipal(ctx, cdp.Collateral.Denom, principal) // set cdp state and indexes in the store collateralToDebtRatio := k.CalculateCollateralToDebtRatio(ctx, cdp.Collateral, cdp.Principal.Add(cdp.AccumulatedFees)) err = k.SetCdpAndCollateralRatioIndex(ctx, cdp, collateralToDebtRatio) if err != nil { return err } return nil } // RepayPrincipal removes debt from the cdp // If all debt is repaid, the collateral is returned to depositors and the cdp is removed from the store func (k Keeper) RepayPrincipal(ctx sdk.Context, owner sdk.AccAddress, denom string, payment sdk.Coin) error { // validation cdp, found := k.GetCdpByOwnerAndDenom(ctx, owner, denom) if !found { return sdkerrors.Wrapf(types.ErrCdpNotFound, "owner %s, denom %s", owner, denom) } err := k.ValidatePaymentCoins(ctx, cdp, payment) if err != nil { return err } // calculate fee and principal payment feePayment, principalPayment := k.calculatePayment(ctx, cdp.Principal.Add(cdp.AccumulatedFees), cdp.AccumulatedFees, payment) err = k.validatePrincipalPayment(ctx, cdp, principalPayment) if err != nil { return err } // send the payment from the sender to the cpd module err = k.supplyKeeper.SendCoinsFromAccountToModule(ctx, owner, types.ModuleName, sdk.NewCoins(feePayment.Add(principalPayment))) if err != nil { return err } // burn the payment coins err = k.supplyKeeper.BurnCoins(ctx, types.ModuleName, sdk.NewCoins(feePayment.Add(principalPayment))) if err != nil { panic(err) } // burn the corresponding amount of debt coins cdpDebt := k.getModAccountDebt(ctx, types.ModuleName) paymentAmount := feePayment.Amount.Add(principalPayment.Amount) coinsToBurn := sdk.NewCoin(k.GetDebtDenom(ctx), paymentAmount) if paymentAmount.GT(cdpDebt) { coinsToBurn = sdk.NewCoin(k.GetDebtDenom(ctx), cdpDebt) } err = k.BurnDebtCoins(ctx, types.ModuleName, k.GetDebtDenom(ctx), coinsToBurn) if err != nil { panic(err) } // emit repayment event ctx.EventManager().EmitEvent( sdk.NewEvent( types.EventTypeCdpRepay, sdk.NewAttribute(sdk.AttributeKeyAmount, feePayment.Add(principalPayment).String()), sdk.NewAttribute(types.AttributeKeyCdpID, fmt.Sprintf("%d", cdp.ID)), ), ) // remove the old collateral:debt ratio index oldCollateralToDebtRatio := k.CalculateCollateralToDebtRatio(ctx, cdp.Collateral, cdp.Principal.Add(cdp.AccumulatedFees)) k.RemoveCdpCollateralRatioIndex(ctx, denom, cdp.ID, oldCollateralToDebtRatio) // update cdp state if !principalPayment.IsZero() { cdp.Principal = cdp.Principal.Sub(principalPayment) } cdp.AccumulatedFees = cdp.AccumulatedFees.Sub(feePayment) // decrement the total principal for the input collateral type k.DecrementTotalPrincipal(ctx, denom, feePayment.Add(principalPayment)) // if the debt is fully paid, return collateral to depositors, // and remove the cdp and indexes from the store if cdp.Principal.IsZero() && cdp.AccumulatedFees.IsZero() { k.ReturnCollateral(ctx, cdp) if err := k.DeleteCDP(ctx, cdp); err != nil { return err } k.RemoveCdpOwnerIndex(ctx, cdp) // emit cdp close event ctx.EventManager().EmitEvent( sdk.NewEvent( types.EventTypeCdpClose, sdk.NewAttribute(types.AttributeKeyCdpID, fmt.Sprintf("%d", cdp.ID)), ), ) return nil } // set cdp state and update indexes collateralToDebtRatio := k.CalculateCollateralToDebtRatio(ctx, cdp.Collateral, cdp.Principal.Add(cdp.AccumulatedFees)) err = k.SetCdpAndCollateralRatioIndex(ctx, cdp, collateralToDebtRatio) if err != nil { return err } return nil } // ValidatePaymentCoins validates that the input coins are valid for repaying debt func (k Keeper) ValidatePaymentCoins(ctx sdk.Context, cdp types.CDP, payment sdk.Coin) error { debt := cdp.Principal.Add(cdp.AccumulatedFees) if payment.Denom != debt.Denom { return sdkerrors.Wrapf(types.ErrInvalidPayment, "cdp %d: expected %s, got %s", cdp.ID, debt.Denom, payment.Denom) } _, found := k.GetDebtParam(ctx, payment.Denom) if !found { return sdkerrors.Wrapf(types.ErrInvalidPayment, "payment denom %s not found", payment.Denom) } return nil } // ReturnCollateral returns collateral to depositors on a cdp and removes deposits from the store func (k Keeper) ReturnCollateral(ctx sdk.Context, cdp types.CDP) { deposits := k.GetDeposits(ctx, cdp.ID) for _, deposit := range deposits { err := k.supplyKeeper.SendCoinsFromModuleToAccount(ctx, types.ModuleName, deposit.Depositor, sdk.NewCoins(deposit.Amount)) if err != nil { panic(err) } k.DeleteDeposit(ctx, cdp.ID, deposit.Depositor) } } // calculatePayment divides the input payment into the portions that will be used to repay fees and principal // owed - Principal + AccumulatedFees // fees - AccumulatedFees // CONTRACT: owned and payment denoms must be checked before calling this function. func (k Keeper) calculatePayment(ctx sdk.Context, owed, fees, payment sdk.Coin) (sdk.Coin, sdk.Coin) { // divides repayment into principal and fee components, with fee payment applied first. feePayment := sdk.NewCoin(payment.Denom, sdk.ZeroInt()) principalPayment := sdk.NewCoin(payment.Denom, sdk.ZeroInt()) var overpayment sdk.Coin // return zero value coins if payment amount is invalid if !payment.Amount.IsPositive() { return feePayment, principalPayment } // check for over payment if payment.Amount.GT(owed.Amount) { overpayment = payment.Sub(owed) payment = payment.Sub(overpayment) } // if no fees, 100% of payment is principal payment if fees.IsZero() { return feePayment, payment } // pay fees before repaying principal if payment.Amount.GT(fees.Amount) { feePayment = fees principalPayment = payment.Sub(fees) } else { feePayment = payment } return feePayment, principalPayment } // validatePrincipalPayment checks that the payment is either full or does not put the cdp below the debt floor // CONTRACT: payment denom must be checked before calling this function. func (k Keeper) validatePrincipalPayment(ctx sdk.Context, cdp types.CDP, payment sdk.Coin) error { proposedBalance := cdp.Principal.Amount.Sub(payment.Amount) dp, _ := k.GetDebtParam(ctx, payment.Denom) if proposedBalance.GT(sdk.ZeroInt()) && proposedBalance.LT(dp.DebtFloor) { return sdkerrors.Wrapf(types.ErrBelowDebtFloor, "proposed %s < minimum %s", sdk.NewCoin(payment.Denom, proposedBalance), dp.DebtFloor) } return nil }