Merge pull request #611 from neutron-org/chore/split-dex-calc-and-exe…

…cution

x/dex/keeper/cancel_limit_order.go

@@ -0,0 +1,92 @@
+package keeper
+
+import (
+	"context"
+
+	sdkerrors "cosmossdk.io/errors"
+	sdk "github.com/cosmos/cosmos-sdk/types"
+
+	"github.com/neutron-org/neutron/v4/x/dex/types"
+)
+
+// CancelLimitOrderCore handles the logic for MsgCancelLimitOrder including bank operations and event emissions.
+func (k Keeper) CancelLimitOrderCore(
+	goCtx context.Context,
+	trancheKey string,
+	callerAddr sdk.AccAddress,
+) error {
+	ctx := sdk.UnwrapSDKContext(goCtx)
+
+	coinOut, tradePairID, err := k.ExecuteCancelLimitOrder(ctx, trancheKey, callerAddr)
+	if err != nil {
+		return err
+	}
+
+	err = k.bankKeeper.SendCoinsFromModuleToAccount(
+		ctx,
+		types.ModuleName,
+		callerAddr,
+		sdk.Coins{coinOut},
+	)
+	if err != nil {
+		return err
+	}
+
+	// This will never panic since TradePairID has already been successfully constructed by ExecuteCancelLimitOrder
+	pairID := tradePairID.MustPairID()
+	ctx.EventManager().EmitEvent(types.CancelLimitOrderEvent(
+		callerAddr,
+		pairID.Token0,
+		pairID.Token1,
+		tradePairID.MakerDenom,
+		tradePairID.TakerDenom,
+		coinOut.Amount,
+		trancheKey,
+	))
+
+	return nil
+}
+
+// ExecuteCancelLimitOrder handles the core logic for CancelLimitOrder -- removing remaining TokenIn from the
+// LimitOrderTranche and returning it to the user, updating the number of canceled shares on the LimitOrderTrancheUser.
+// IT DOES NOT PERFORM ANY BANKING OPERATIONS
+func (k Keeper) ExecuteCancelLimitOrder(
+	ctx sdk.Context,
+	trancheKey string,
+	callerAddr sdk.AccAddress,
+) (coinOut sdk.Coin, tradePairID *types.TradePairID, error error) {
+	trancheUser, found := k.GetLimitOrderTrancheUser(ctx, callerAddr.String(), trancheKey)
+	if !found {
+		return sdk.Coin{}, nil, types.ErrActiveLimitOrderNotFound
+	}
+
+	tradePairID, tickIndex := trancheUser.TradePairId, trancheUser.TickIndexTakerToMaker
+	tranche := k.GetLimitOrderTranche(
+		ctx,
+		&types.LimitOrderTrancheKey{
+			TradePairId:           tradePairID,
+			TickIndexTakerToMaker: tickIndex,
+			TrancheKey:            trancheKey,
+		},
+	)
+	if tranche == nil {
+		return sdk.Coin{}, nil, types.ErrActiveLimitOrderNotFound
+	}
+
+	amountToCancel := tranche.RemoveTokenIn(trancheUser)
+	trancheUser.SharesCancelled = trancheUser.SharesCancelled.Add(amountToCancel)
+
+	if !amountToCancel.IsPositive() {
+		return sdk.Coin{}, nil, sdkerrors.Wrapf(types.ErrCancelEmptyLimitOrder, "%s", tranche.Key.TrancheKey)
+	}
+
+	k.SaveTrancheUser(ctx, trancheUser)
+	k.SaveTranche(ctx, tranche)
+
+	if trancheUser.OrderType.HasExpiration() {
+		k.RemoveLimitOrderExpiration(ctx, *tranche.ExpirationTime, tranche.Key.KeyMarshal())
+	}
+	coinOut = sdk.NewCoin(tradePairID.MakerDenom, amountToCancel)
+
+	return coinOut, tradePairID, nil
+}