package keeper import ( sdk "github.com/cosmos/cosmos-sdk/types" "github.com/kava-labs/kava/x/cdp/types" ) const ( // factor for setting the initial value of gov tokens to sell at debt auctions -- assuming stable token is ~1 usd, this starts the auction with a price of $0.01 KAVA dump = 100 ) // AuctionCollateral creates auctions from the input deposits which attempt to raise the corresponding amount of debt func (k Keeper) AuctionCollateral(ctx sdk.Context, deposits types.Deposits, collateralType string, debt sdk.Int, bidDenom string) error { auctionSize := k.getAuctionSize(ctx, collateralType) totalCollateral := deposits.SumCollateral() for _, deposit := range deposits { debtCoveredByDeposit := (sdk.NewDecFromInt(deposit.Amount.Amount).Quo(sdk.NewDecFromInt(totalCollateral))).Mul(sdk.NewDecFromInt(debt)).RoundInt() err := k.CreateAuctionsFromDeposit(ctx, deposit.Amount, collateralType, deposit.Depositor, debtCoveredByDeposit, auctionSize, bidDenom) if err != nil { return err } } return nil } // CreateAuctionsFromDeposit creates auctions from the input deposit func (k Keeper) CreateAuctionsFromDeposit( ctx sdk.Context, collateral sdk.Coin, collateralType string, returnAddr sdk.AccAddress, debt, auctionSize sdk.Int, principalDenom string) error { // number of auctions of auctionSize numberOfAuctions := collateral.Amount.Quo(auctionSize) debtPerAuction := debt.Mul(auctionSize).Quo(collateral.Amount) // last auction for remaining collateral (collateral < auctionSize) lastAuctionCollateral := collateral.Amount.Mod(auctionSize) lastAuctionDebt := debt.Mul(lastAuctionCollateral).Quo(collateral.Amount) // amount of debt that has not been allocated due to // rounding error (unallocated debt is less than numberOfAuctions + 1) unallocatedDebt := debt.Sub(numberOfAuctions.Mul(debtPerAuction).Add(lastAuctionDebt)) // rounding error for whole and last auctions in units of collateral // higher value means a larger truncation wholeAuctionError := debt.Mul(auctionSize).Mod(collateral.Amount) lastAuctionError := debt.Mul(lastAuctionCollateral).Mod(collateral.Amount) // if last auction has larger rounding error, then allocate one debt to last auction first // follows the largest remainder method https://en.wikipedia.org/wiki/Largest_remainder_method if lastAuctionError.GT(wholeAuctionError) { lastAuctionDebt = lastAuctionDebt.Add(sdk.OneInt()) unallocatedDebt = unallocatedDebt.Sub(sdk.OneInt()) } debtDenom := k.GetDebtDenom(ctx) numAuctions := numberOfAuctions.Int64() // create whole auctions for i := int64(0); i < numAuctions; i++ { debtAmount := debtPerAuction // distribute unallocated debt left over starting with first auction created if unallocatedDebt.IsPositive() { debtAmount = debtAmount.Add(sdk.OneInt()) unallocatedDebt = unallocatedDebt.Sub(sdk.OneInt()) } penalty := k.ApplyLiquidationPenalty(ctx, collateralType, debtAmount) _, err := k.auctionKeeper.StartCollateralAuction( ctx, types.LiquidatorMacc, sdk.NewCoin(collateral.Denom, auctionSize), sdk.NewCoin(principalDenom, debtAmount.Add(penalty)), []sdk.AccAddress{returnAddr}, []sdk.Int{auctionSize}, sdk.NewCoin(debtDenom, debtAmount), ) if err != nil { return err } } // skip last auction if there is no collateral left to auction if !lastAuctionCollateral.IsPositive() { return nil } // if the last auction had a larger rounding error than whole auctions, // then unallocatedDebt will be zero since we will have already distributed // all of the unallocated debt if unallocatedDebt.IsPositive() { lastAuctionDebt = lastAuctionDebt.Add(sdk.OneInt()) unallocatedDebt = unallocatedDebt.Sub(sdk.OneInt()) } penalty := k.ApplyLiquidationPenalty(ctx, collateralType, lastAuctionDebt) _, err := k.auctionKeeper.StartCollateralAuction( ctx, types.LiquidatorMacc, sdk.NewCoin(collateral.Denom, lastAuctionCollateral), sdk.NewCoin(principalDenom, lastAuctionDebt.Add(penalty)), []sdk.AccAddress{returnAddr}, []sdk.Int{lastAuctionCollateral}, sdk.NewCoin(debtDenom, lastAuctionDebt), ) return err } // NetSurplusAndDebt burns surplus and debt coins equal to the minimum of surplus and debt balances held by the liquidator module account // for example, if there is 1000 debt and 100 surplus, 100 surplus and 100 debt are burned, netting to 900 debt func (k Keeper) NetSurplusAndDebt(ctx sdk.Context) error { totalSurplus := k.GetTotalSurplus(ctx, types.LiquidatorMacc) debt := k.GetTotalDebt(ctx, types.LiquidatorMacc) netAmount := sdk.MinInt(totalSurplus, debt) if netAmount.IsZero() { return nil } // burn debt coins equal to netAmount err := k.supplyKeeper.BurnCoins(ctx, types.LiquidatorMacc, sdk.NewCoins(sdk.NewCoin(k.GetDebtDenom(ctx), netAmount))) if err != nil { return err } // burn stable coins equal to min(balance, netAmount) dp := k.GetParams(ctx).DebtParam balance := k.supplyKeeper.GetModuleAccount(ctx, types.LiquidatorMacc).GetCoins().AmountOf(dp.Denom) burnAmount := sdk.MinInt(balance, netAmount) return k.supplyKeeper.BurnCoins(ctx, types.LiquidatorMacc, sdk.NewCoins(sdk.NewCoin(dp.Denom, burnAmount))) } // GetTotalSurplus returns the total amount of surplus tokens held by the liquidator module account func (k Keeper) GetTotalSurplus(ctx sdk.Context, accountName string) sdk.Int { acc := k.supplyKeeper.GetModuleAccount(ctx, accountName) dp := k.GetParams(ctx).DebtParam return acc.GetCoins().AmountOf(dp.Denom) } // GetTotalDebt returns the total amount of debt tokens held by the liquidator module account func (k Keeper) GetTotalDebt(ctx sdk.Context, accountName string) sdk.Int { acc := k.supplyKeeper.GetModuleAccount(ctx, accountName) return acc.GetCoins().AmountOf(k.GetDebtDenom(ctx)) } // RunSurplusAndDebtAuctions nets the surplus and debt balances and then creates surplus or debt auctions if the remaining balance is above the auction threshold parameter func (k Keeper) RunSurplusAndDebtAuctions(ctx sdk.Context) error { if err := k.NetSurplusAndDebt(ctx); err != nil { return err } remainingDebt := k.GetTotalDebt(ctx, types.LiquidatorMacc) params := k.GetParams(ctx) if remainingDebt.GTE(params.DebtAuctionThreshold) { debtLot := sdk.NewCoin(k.GetDebtDenom(ctx), params.DebtAuctionLot) bidCoin := sdk.NewCoin(params.DebtParam.Denom, debtLot.Amount) initialLot := sdk.NewCoin(k.GetGovDenom(ctx), debtLot.Amount.Mul(sdk.NewInt(dump))) _, err := k.auctionKeeper.StartDebtAuction(ctx, types.LiquidatorMacc, bidCoin, initialLot, debtLot) if err != nil { return err } } surplus := k.supplyKeeper.GetModuleAccount(ctx, types.LiquidatorMacc).GetCoins().AmountOf(params.DebtParam.Denom) if !surplus.GTE(params.SurplusAuctionThreshold) { return nil } surplusLot := sdk.NewCoin(params.DebtParam.Denom, sdk.MinInt(params.SurplusAuctionLot, surplus)) _, err := k.auctionKeeper.StartSurplusAuction(ctx, types.LiquidatorMacc, surplusLot, k.GetGovDenom(ctx)) return err }