Implement bep3 evm native conversion logic (#1848)

* Implement bep3 evm native conversion logic

* Update changelog

* Fix indentation

* Add bep3 conversion keeper tests

* make DefaultBEP3ConversionDenoms private

* refactor bep3 conversion

* update bep3 tests to cover all bep3 assets

* minor refactor

CHANGELOG.md

@@ -45,6 +45,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 - (validator-vesting) [#1832] Add grpc query service to replace removed legacy querier
 - (incentive) [#1836] Update x/incentive cli to use grpc query client
 - (ibc) [#1839] Add ibc packet forward middleware for ibc transfers
+- (evmutil) [#1848] Update evm native conversion logic to handle bep3 assets
 
 ## [v0.25.0]
 
@@ -328,6 +329,7 @@ the [changelog](https://github.com/cosmos/cosmos-sdk/blob/v0.38.4/CHANGELOG.md).
   large-scale simulations remotely using aws-batch
 
 [#1846]: https://github.com/Kava-Labs/kava/pull/1846
+[#1848]: https://github.com/Kava-Labs/kava/pull/1848
 [#1839]: https://github.com/Kava-Labs/kava/pull/1839
 [#1836]: https://github.com/Kava-Labs/kava/pull/1836
 [#1832]: https://github.com/Kava-Labs/kava/pull/1832

x/evmutil/keeper/conversion_evm_native.go

@@ -71,7 +71,15 @@ func (k Keeper) ConvertCoinToERC20(
 		return err
 	}
 
-	if err := k.UnlockERC20Tokens(ctx, pair, coin.Amount.BigInt(), receiverAccount); err != nil {
+	// handle bep3 conversion pair (8 decimals sdk.Coin -> 18 decimals erc20)
+	// when converting bep3 bank coins to erc20, we will need to unlock the 18
+	// decimals erc20 equivalent of the 8 decimals bep3 sdk.Coins
+	amountToUnlock := coin.Amount.BigInt()
+	if isBep3Asset(pair.Denom) {
+		amountToUnlock = convertBep3CoinAmountToERC20Amount(coin.Amount.BigInt())
+	}
+
+	if err := k.UnlockERC20Tokens(ctx, pair, amountToUnlock, receiverAccount); err != nil {
 		return err
 	}
 
@@ -102,13 +110,23 @@ func (k Keeper) ConvertERC20ToCoin(
 		return err
 	}
 
+	amountToLock := amount.BigInt()
+	amountToMint := amount.BigInt()
+
+	if isBep3Asset(pair.Denom) {
+		amountToMint, amountToLock, err = bep3ERC20AmountToCoinMintAndERC20LockAmount(amount.BigInt())
+		if err != nil {
+			return err
+		}
+	}
+
 	// lock erc20 tokens
-	if err := k.LockERC20Tokens(ctx, pair, amount.BigInt(), initiator); err != nil {
+	if err := k.LockERC20Tokens(ctx, pair, amountToLock, initiator); err != nil {
 		return err
 	}
 
 	// mint conversion pair coin
-	coin, err := k.MintConversionPairCoin(ctx, pair, amount.BigInt(), receiver)
+	coin, err := k.MintConversionPairCoin(ctx, pair, amountToMint, receiver)
 	if err != nil {
 		return err
 	}

x/evmutil/keeper/conversion_evm_native_bep3.go

@@ -0,0 +1,55 @@
+package keeper
+
+import (
+	"math/big"
+
+	errorsmod "cosmossdk.io/errors"
+	"github.com/kava-labs/kava/x/evmutil/types"
+)
+
+var (
+	bep3Denoms = map[string]bool{
+		"bnb":  true,
+		"busd": true,
+		"btcb": true,
+		"xrpb": true,
+	}
+
+	bep3ConversionFactor = new(big.Int).Exp(big.NewInt(10), big.NewInt(10), nil)
+)
+
+func isBep3Asset(denom string) bool {
+	return bep3Denoms[denom]
+}
+
+// convertBep3CoinAmountToERC20Amount converts a bep3 coin amount with 8 decimals
+// to the equivalent ERC20 token with 18 decimals.
+func convertBep3CoinAmountToERC20Amount(amount *big.Int) (erc20Amount *big.Int) {
+	return new(big.Int).Mul(amount, bep3ConversionFactor)
+}
+
+// convertBep3ERC20AmountToCoinAmount converts a bep3 ERC20 token with 18 decimals
+// to the equivalent coin amount with 8 decimals, and dropping the remainder.
+func convertBep3ERC20AmountToCoinAmount(amount *big.Int) (coinAmount *big.Int) {
+	return new(big.Int).Div(amount, bep3ConversionFactor)
+}
+
+// bep3ERC20AmountToCoinMintAndERC20LockAmount converts 18 decimals erc20 bep3
+// amount to the equivalent 8 decimals coin amount to mint, and the
+// 18 decimals erc20 bep3 amount to lock for the converted coin amount.
+func bep3ERC20AmountToCoinMintAndERC20LockAmount(amount *big.Int) (
+	amountToMint *big.Int, amountToLock *big.Int, err error,
+) {
+	amountToMint = convertBep3ERC20AmountToCoinAmount(amount)
+
+	// make sure we have at least 1 sdk.Coin to mint
+	if amountToMint.Cmp(big.NewInt(0)) == 0 {
+		err := errorsmod.Wrapf(
+			types.ErrInsufficientConversionAmount,
+			"unable to convert bep3 coin due converting less than 1 native unit",
+		)
+		return nil, nil, err
+	}
+	amountToLock = convertBep3CoinAmountToERC20Amount(amountToMint)
+	return amountToMint, amountToLock, nil
+}