[TRA-139] Add logic to transfer collateral when open/close isolated p…

…erpetual position.

protocol/x/subaccounts/keeper/isolated_subaccount.go

@@ -2,16 +2,35 @@ package keeper
 
 import (
 	"math"
+	"math/big"
 
 	errorsmod "cosmossdk.io/errors"
 	sdk "github.com/cosmos/cosmos-sdk/types"
 	"github.com/dydxprotocol/v4-chain/protocol/lib"
+	assettypes "github.com/dydxprotocol/v4-chain/protocol/x/assets/types"
 	perptypes "github.com/dydxprotocol/v4-chain/protocol/x/perpetuals/types"
 	"github.com/dydxprotocol/v4-chain/protocol/x/subaccounts/types"
 )
 
+type positionStateTransition uint
+
+const (
+	opened positionStateTransition = iota
+	closed
+)
+
+// Represents a state transition for an isolated perpetual.
+type isolatedPerpetualStateTranisition struct {
+	perpetualId uint32
+	// TODO(DEC-715): Support non-USDC assets.
+	// USDC position size of the subaccount that has a state change for an isolated perpetual.
+	usdcQuantumsBeforeUpdate *big.Int
+	transition               positionStateTransition
+}
+
 // checkIsolatedSubaccountConstaints will validate all `updates` to the relevant subaccounts against
-// isolated subaccount constraints.
+// isolated subaccount constraints and computes whether each update leads to a state change
+// (open / close) to an isolated perpetual occurred due to the updates if they are valid.
 // This function checks each update in isolation, so if multiple updates for the same subaccount id
 // are passed in, they are not evaluated separately.
 // The input subaccounts must be settled.
@@ -20,72 +39,88 @@ import (
 // Returns a `successPerUpdates` value, which is a slice of `UpdateResult`.
 // These map to the updates and are used to indicate which of the updates
 // caused a failure, if any.
+// Returns a `isolatedPerpetualStateTransitions` value, which is a slice of
+// `isolatedPerpetualStateTransition`.
+// These map to the updates and are used to indicate which of the updates opened or closed an
+// isolated perpetual position.
 func (k Keeper) checkIsolatedSubaccountConstraints(
 	ctx sdk.Context,
 	settledUpdates []settledUpdate,
 	perpetuals []perptypes.Perpetual,
 ) (
 	success bool,
 	successPerUpdate []types.UpdateResult,
+	isolatedPerpetualStateTranisitions []*isolatedPerpetualStateTranisition,
 	err error,
 ) {
 	success = true
 	successPerUpdate = make([]types.UpdateResult, len(settledUpdates))
+	isolatedPerpetualStateTranisitions = make([]*isolatedPerpetualStateTranisition, len(settledUpdates))
 	var perpIdToMarketType = make(map[uint32]perptypes.PerpetualMarketType)
 
 	for _, perpetual := range perpetuals {
 		perpIdToMarketType[perpetual.GetId()] = perpetual.Params.MarketType
 	}
 
 	for i, u := range settledUpdates {
-		result, err := isValidIsolatedPerpetualUpdates(u, perpIdToMarketType)
+		result, stateTransition, err := processIsolatedPerpetualUpdates(u, perpIdToMarketType)
 		if err != nil {
-			return false, nil, err
+			return false, nil, nil, err
 		}
 		if result != types.Success {
 			success = false
 		}
 
 		successPerUpdate[i] = result
+		isolatedPerpetualStateTranisitions[i] = stateTransition
 	}
 
-	return success, successPerUpdate, nil
+	return success, successPerUpdate, isolatedPerpetualStateTranisitions, nil
 }
 
-// Checks whether the perpetual updates to a settled subaccount violates constraints for isolated
-// perpetuals. This function assumes the settled subaccount is valid and does not violate the
-// the constraints.
+// processIsolatedPerpetualUpdates checks whether the perpetual updates to a settled subaccount
+// violates constraints for isolated perpetuals and computes whether the perpetual updates result in
+// a state change (open / close) for an isolated perpetual position if the updates are valid.
+// This function assumes the settled subaccount is valid and does not violate the constraints.
 // The constraint being checked is:
 //   - a subaccount with a position in an isolated perpetual cannot have updates for other
 //     perpetuals
 //   - a subaccount with a position in a non-isolated perpetual cannot have updates for isolated
 //     perpetuals
 //   - a subaccount with no positions cannot be updated to have positions in multiple isolated
 //     perpetuals or a combination of isolated and non-isolated perpetuals
-func isValidIsolatedPerpetualUpdates(
+//
+// If there is a state change (open / close) from the perpetual updates, it is returned along with
+// the perpetual id of the isolated perpetual and the size of the USDC position in the subaccount.
+func processIsolatedPerpetualUpdates(
 	settledUpdate settledUpdate,
 	perpIdToMarketType map[uint32]perptypes.PerpetualMarketType,
-) (types.UpdateResult, error) {
+) (types.UpdateResult, *isolatedPerpetualStateTranisition, error) {
 	// If there are no perpetual updates, then this update does not violate constraints for isolated
 	// markets.
 	if len(settledUpdate.PerpetualUpdates) == 0 {
-		return types.Success, nil
+		return types.Success, nil, nil
 	}
 
 	// Check if the updates contain an update to an isolated perpetual.
 	hasIsolatedUpdate := false
 	isolatedUpdatePerpetualId := uint32(math.MaxUint32)
+	isolatedUpdate := (*types.PerpetualUpdate)(nil)
 	for _, perpetualUpdate := range settledUpdate.PerpetualUpdates {
 		marketType, exists := perpIdToMarketType[perpetualUpdate.PerpetualId]
 		if !exists {
-			return types.UpdateCausedError, errorsmod.Wrap(
+			return types.UpdateCausedError, nil, errorsmod.Wrap(
 				perptypes.ErrPerpetualDoesNotExist, lib.UintToString(perpetualUpdate.PerpetualId),
 			)
 		}
 
 		if marketType == perptypes.PerpetualMarketType_PERPETUAL_MARKET_TYPE_ISOLATED {
 			hasIsolatedUpdate = true
 			isolatedUpdatePerpetualId = perpetualUpdate.PerpetualId
+			isolatedUpdate = &types.PerpetualUpdate{
+				PerpetualId:      perpetualUpdate.PerpetualId,
+				BigQuantumsDelta: perpetualUpdate.GetBigQuantums(),
+			}
 			break
 		}
 	}
@@ -94,38 +129,40 @@ func isValidIsolatedPerpetualUpdates(
 	// Assumes the subaccount itself does not violate the isolated perpetual constraints.
 	isIsolatedSubaccount := false
 	isolatedPositionPerpetualId := uint32(math.MaxUint32)
+	isolatedPerpetualPosition := (*types.PerpetualPosition)(nil)
 	hasPerpetualPositions := len(settledUpdate.SettledSubaccount.PerpetualPositions) > 0
 	for _, perpetualPosition := range settledUpdate.SettledSubaccount.PerpetualPositions {
 		marketType, exists := perpIdToMarketType[perpetualPosition.PerpetualId]
 		if !exists {
-			return types.UpdateCausedError, errorsmod.Wrap(
+			return types.UpdateCausedError, nil, errorsmod.Wrap(
 				perptypes.ErrPerpetualDoesNotExist, lib.UintToString(perpetualPosition.PerpetualId),
 			)
 		}
 
 		if marketType == perptypes.PerpetualMarketType_PERPETUAL_MARKET_TYPE_ISOLATED {
 			isIsolatedSubaccount = true
 			isolatedPositionPerpetualId = perpetualPosition.PerpetualId
+			isolatedPerpetualPosition = perpetualPosition
 			break
 		}
 	}
 
 	// A subaccount with a perpetual position in an isolated perpetual cannot have updates to other
 	// non-isolated perpetuals.
 	if isIsolatedSubaccount && !hasIsolatedUpdate {
-		return types.ViolatesIsolatedSubaccountConstraints, nil
+		return types.ViolatesIsolatedSubaccountConstraints, nil, nil
 	}
 
 	// A subaccount with perpetual positions in non-isolated perpetuals cannot have an update
 	// to an isolated perpetual.
 	if !isIsolatedSubaccount && hasPerpetualPositions && hasIsolatedUpdate {
-		return types.ViolatesIsolatedSubaccountConstraints, nil
+		return types.ViolatesIsolatedSubaccountConstraints, nil, nil
 	}
 
 	// There cannot be more than a single perpetual update if an update to an isolated perpetual
 	// exists in the slice of perpetual updates.
 	if hasIsolatedUpdate && len(settledUpdate.PerpetualUpdates) > 1 {
-		return types.ViolatesIsolatedSubaccountConstraints, nil
+		return types.ViolatesIsolatedSubaccountConstraints, nil, nil
 	}
 
 	// Note we can assume that if `hasIsolatedUpdate` is true, there is only a single perpetual
@@ -135,8 +172,130 @@ func isValidIsolatedPerpetualUpdates(
 	if isIsolatedSubaccount &&
 		hasIsolatedUpdate &&
 		isolatedPositionPerpetualId != isolatedUpdatePerpetualId {
-		return types.ViolatesIsolatedSubaccountConstraints, nil
+		return types.ViolatesIsolatedSubaccountConstraints, nil, nil
+	}
+
+	return types.Success,
+		getIsolatedPerpetualStateTransition(
+			settledUpdate.SettledSubaccount,
+			isolatedPerpetualPosition,
+			isolatedUpdate,
+		),
+		nil
+}
+
+// getIsolatedPerpetualStateTransition computes whether an isolated perpetual position will be
+// opened or closed for a subaccount given an isolated perpetual update for the subaccount.
+// Input subaccount account must be settled.
+func getIsolatedPerpetualStateTransition(
+	settledSubaccount types.Subaccount,
+	isolatedPerpetualPosition *types.PerpetualPosition,
+	isolatedPerpetualUpdate *types.PerpetualUpdate,
+) *isolatedPerpetualStateTranisition {
+	// If there is no update to an isolated perpetual position, then no state transitions have
+	// happened for the isolated perpetual.
+	if isolatedPerpetualUpdate == nil {
+		return nil
+	}
+
+	perpetualId := isolatedPerpetualUpdate.PerpetualId
+	// TODO(DEC-715): Support non-USDC assets.
+	usdcQuantumsBeforeUpdate := new(big.Int).Set(settledSubaccount.GetUsdcPosition())
+
+	// If the subaccount has no isolated perpetual position, then this update is opening an isolated
+	// perpetual position.
+	if isolatedPerpetualPosition == nil {
+		return &isolatedPerpetualStateTranisition{
+			perpetualId:              perpetualId,
+			usdcQuantumsBeforeUpdate: usdcQuantumsBeforeUpdate,
+			transition:               opened,
+		}
+	}
+
+	// If the position size after the update is zero, then this update is closing an isolated
+	// perpetual position.
+	if finalPositionSize := new(big.Int).Add(
+		isolatedPerpetualPosition.GetBigQuantums(),
+		isolatedPerpetualUpdate.GetBigQuantums(),
+	); finalPositionSize.Cmp(lib.BigInt0()) == 0 {
+		return &isolatedPerpetualStateTranisition{
+			perpetualId:              perpetualId,
+			usdcQuantumsBeforeUpdate: usdcQuantumsBeforeUpdate,
+			transition:               closed,
+		}
+	}
+
+	// If a position was not opened or closed, no state transition happened from the perpetual
+	// update.
+	return nil
+}
+
+// transferCollateralForIsolatedPerpetual transfers collateral between an isolated collateral pool
+// and the cross-perpetual collateral pool based on whether an isolated perpetual position was
+// opened or closed in a subaccount.
+// Note: This uses the `x/bank` keeper and modifies `x/bank` state.
+func (k *Keeper) transferCollateralForIsolatedPerpetual(
+	ctx sdk.Context,
+	updatedSubaccount types.Subaccount,
+	stateTransition *isolatedPerpetualStateTranisition,
+) error {
+	// No collateral to transfer if no state transition.
+	if stateTransition == nil {
+		return nil
+	}
+
+	isolatedCollateralPoolAddr, err := k.GetCollateralPoolFromPerpetualId(ctx, stateTransition.perpetualId)
+	if err != nil {
+		return err
+	}
+
+	// If an isolated perpetual position was opened in the subaccount, then move collateral equivalent
+	// to the USDC asset position size of the subaccount before the update from the
+	// cross-perpetual collateral pool to the isolated perpetual collateral pool.
+	if stateTransition.transition == opened {
+		_, coinToTransfer, err := k.assetsKeeper.ConvertAssetToCoin(
+			ctx,
+			// TODO(DEC-715): Support non-USDC assets.
+			assettypes.AssetUsdc.Id,
+			stateTransition.usdcQuantumsBeforeUpdate,
+		)
+		if err != nil {
+			return err
+		}
+
+		if err := k.bankKeeper.SendCoins(
+			ctx,
+			types.ModuleAddress,
+			isolatedCollateralPoolAddr,
+			[]sdk.Coin{coinToTransfer},
+		); err != nil {
+			return err
+		}
+		return nil
+		// If the isolated perpetual position was closed, then move collateral equivalent to the USDC
+		// asset position size of the subaccount after the update from the isolated perpetual collateral
+		// pool to the cross-perpetual collateral pool.
+	} else if stateTransition.transition == closed {
+		_, coinToTransfer, err := k.assetsKeeper.ConvertAssetToCoin(
+			ctx,
+			// TODO(DEC-715): Support non-USDC assets.
+			assettypes.AssetUsdc.Id,
+			updatedSubaccount.GetUsdcPosition(),
+		)
+		if err != nil {
+			return err
+		}
+
+		if err := k.bankKeeper.SendCoins(
+			ctx,
+			isolatedCollateralPoolAddr,
+			types.ModuleAddress,
+			[]sdk.Coin{coinToTransfer},
+		); err != nil {
+			return err
+		}
+		return nil
 	}
 
-	return types.Success, nil
+	return nil
 }