add minimum staking amount limitation for farming

Author: keithsue

api/side/farming/params.pulsar.go

@@ -18,6 +18,11 @@ message Asset {
       (gogoproto.customtype) = "cosmossdk.io/math.LegacyDec",
       (gogoproto.nullable)   = false
     ];
+    // Minimum staking amount
+    string min_staking_amount = 3 [
+      (gogoproto.customtype) = "cosmossdk.io/math.Int",
+      (gogoproto.nullable) = false
+    ];
 }
 
 // Params defines the parameters for the module.

proto/side/farming/params.proto

@@ -32,6 +32,11 @@ func (m msgServer) Stake(goCtx context.Context, msg *types.MsgStake) (*types.Msg
 		return nil, errorsmod.Wrapf(types.ErrAssetNotEligible, "asset %s not eligible", msg.Amount.Denom)
 	}
 
+	asset := m.Asset(ctx, msg.Amount.Denom)
+	if msg.Amount.Amount.LT(asset.MinStakingAmount) {
+		return nil, errorsmod.Wrapf(types.ErrInvalidAmount, "amount cannot be less than min staking amount %s", asset.MinStakingAmount)
+	}
+
 	if !m.LockDurationExists(ctx, msg.LockDuration) {
 		return nil, types.ErrInvalidLockDuration
 	}

x/farming/keeper/msg_server.go

@@ -50,6 +50,17 @@ func (k Keeper) IsEligibleAsset(ctx sdk.Context, denom string) bool {
 	return false
 }
 
+// Asset gets the asset by the given denom
+func (k Keeper) Asset(ctx sdk.Context, denom string) types.Asset {
+	for _, asset := range k.EligibleAssets(ctx) {
+		if asset.Denom == denom {
+			return asset
+		}
+	}
+
+	return types.Asset{}
+}
+
 // OnParamsChanged is called when the params are changed
 func (k Keeper) OnParamsChanged(ctx sdk.Context, params types.Params, newParams types.Params) {
 	if !params.Enabled && newParams.Enabled {

x/farming/keeper/params.go

@@ -132,12 +132,12 @@ func validateEligibleAssets(p Params) error {
 			return errorsmod.Wrapf(ErrInvalidParams, "invalid asset denom: %v", err)
 		}
 
-		if asset.RewardRatio.IsNegative() {
-			return errorsmod.Wrap(ErrInvalidParams, "asset reward ratio cannot be negative")
+		if err := validateRewardRatio(asset.RewardRatio); err != nil {
+			return err
 		}
 
-		if asset.RewardRatio.GT(sdkmath.LegacyOneDec()) {
-			return errorsmod.Wrap(ErrInvalidParams, "asset reward ratio cannot be greater than 1")
+		if !asset.MinStakingAmount.IsPositive() {
+			return errorsmod.Wrapf(ErrInvalidParams, "min staking amount must be positive")
 		}
 
 		totalRewardRatio = totalRewardRatio.Add(asset.RewardRatio)
@@ -150,3 +150,16 @@ func validateEligibleAssets(p Params) error {
 
 	return nil
 }
+
+// validateRewardRatio validates the given reward ratio
+func validateRewardRatio(rewardRatio sdkmath.LegacyDec) error {
+	if rewardRatio.IsNegative() {
+		return errorsmod.Wrap(ErrInvalidParams, "asset reward ratio cannot be negative")
+	}
+
+	if rewardRatio.GT(sdkmath.LegacyOneDec()) {
+		return errorsmod.Wrap(ErrInvalidParams, "asset reward ratio cannot be greater than 1")
+	}
+
+	return nil
+}