reduce tokens in targetsupply when burning

app/keepers/keepers.go

@@ -525,7 +525,7 @@ func NewAppKeepers(
 	// 	return wasmkeeper.NewBurnCoinMessageHandler(customBurner)
 	// })
 
-	junoBurnerPlugin := junoburn.NewBurnerPlugin(appKeepers.BankKeeper)
+	junoBurnerPlugin := junoburn.NewBurnerPlugin(appKeepers.BankKeeper, appKeepers.MintKeeper)
 	burnOverride := wasmkeeper.WithMessageHandler(wasmkeeper.NewBurnCoinMessageHandler(junoBurnerPlugin))
 	wasmOpts = append(wasmOpts, burnOverride)
 

x/burn/burner.go

@@ -3,6 +3,7 @@ package burn
 import (
 	wasmtypes "github.com/CosmWasm/wasmd/x/wasm/types"
 
+	mintkeeper "github.com/CosmosContracts/juno/v17/x/mint/keeper"
 	sdk "github.com/cosmos/cosmos-sdk/types"
 	bankkeeper "github.com/cosmos/cosmos-sdk/x/bank/keeper"
 )
@@ -11,17 +12,34 @@ import (
 
 type BurnerWasmPlugin struct {
 	bk bankkeeper.Keeper
+	mk mintkeeper.Keeper
 }
 
 var _ wasmtypes.Burner = &BurnerWasmPlugin{}
 
-func NewBurnerPlugin(bk bankkeeper.Keeper) *BurnerWasmPlugin {
-	return &BurnerWasmPlugin{bk: bk}
+func NewBurnerPlugin(bk bankkeeper.Keeper, mk mintkeeper.Keeper) *BurnerWasmPlugin {
+	return &BurnerWasmPlugin{bk: bk, mk: mk}
 }
 
-func (k *BurnerWasmPlugin) BurnCoins(_ sdk.Context, _ string, _ sdk.Coins) error {
-	// instead of burning, we just hold in balance and subtract from the x/mint module's total supply
-	// return k.bk.BurnCoins(ctx, moduleName, amt)
+func (k *BurnerWasmPlugin) BurnCoins(ctx sdk.Context, moduleName string, amt sdk.Coins) error {
+	// first, try to burn the coins on bank module
+	err := k.bk.BurnCoins(ctx, moduleName, amt)
+	if err != nil {
+		return err
+	}
+
+	// get mint params
+	params := k.mk.GetParams(ctx)
+
+	// loop the burned coins
+	for _, amount := range amt {
+
+		// if we are burning mint denom, reduce the target staking supply
+		if amount.Denom == params.MintDenom {
+			k.mk.ReduceTargetSupply(ctx, amount)
+		}
+	}
+
 	return nil
 }
 

x/mint/keeper/keeper.go

@@ -153,6 +153,20 @@ func (k Keeper) MintCoins(ctx sdk.Context, newCoins sdk.Coins) error {
 	return k.bankKeeper.MintCoins(ctx, types.ModuleName, newCoins)
 }
 
+func (k Keeper) ReduceTargetSupply(ctx sdk.Context, burnCoin sdk.Coin) error {
+	params := k.GetParams(ctx)
+
+	if burnCoin.Denom != params.MintDenom {
+		return fmt.Errorf("Tried reducing target supply with non staking token")
+	}
+
+	minter := k.GetMinter(ctx)
+	minter.TargetSupply = minter.TargetSupply.Sub(burnCoin.Amount)
+	k.SetMinter(ctx, minter)
+
+	return nil
+}
+
 // AddCollectedFees implements an alias call to the underlying supply keeper's
 // AddCollectedFees to be used in BeginBlocker.
 func (k Keeper) AddCollectedFees(ctx sdk.Context, fees sdk.Coins) error {