package ante

import (
	"errors"
	"math"
	"math/big"
	"strconv"

	sdkmath "cosmossdk.io/math"

	storetypes "github.com/cosmos/cosmos-sdk/store/types"
	sdk "github.com/cosmos/cosmos-sdk/types"
	sdkerrors "github.com/cosmos/cosmos-sdk/types/errors"
	authante "github.com/cosmos/cosmos-sdk/x/auth/ante"

	ethermint "github.com/evmos/ethermint/types"
	evmkeeper "github.com/evmos/ethermint/x/evm/keeper"
	"github.com/evmos/ethermint/x/evm/statedb"
	evmtypes "github.com/evmos/ethermint/x/evm/types"

	"github.com/ethereum/go-ethereum/common"
	ethtypes "github.com/ethereum/go-ethereum/core/types"
)

// EthSigVerificationDecorator validates an ethereum signatures
type EthSigVerificationDecorator struct {
	evmKeeper EVMKeeper
}

// NewEthSigVerificationDecorator creates a new EthSigVerificationDecorator
func NewEthSigVerificationDecorator(ek EVMKeeper) EthSigVerificationDecorator {
	return EthSigVerificationDecorator{
		evmKeeper: ek,
	}
}

// AnteHandle validates checks that the registered chain id is the same as the one on the message, and
// that the signer address matches the one defined on the message.
// It's not skipped for RecheckTx, because it set `From` address which is critical from other ante handler to work.
// Failure in RecheckTx will prevent tx to be included into block, especially when CheckTx succeed, in which case user
// won't see the error message.
func (esvd EthSigVerificationDecorator) AnteHandle(ctx sdk.Context, tx sdk.Tx, simulate bool, next sdk.AnteHandler) (newCtx sdk.Context, err error) {
	chainID := esvd.evmKeeper.ChainID()
	chainCfg := esvd.evmKeeper.GetChainConfig(ctx)
	ethCfg := chainCfg.EthereumConfig(chainID)
	blockNum := big.NewInt(ctx.BlockHeight())
	signer := ethtypes.MakeSigner(ethCfg, blockNum)

	for _, msg := range tx.GetMsgs() {
		msgEthTx, ok := msg.(*evmtypes.MsgEthereumTx)
		if !ok {
			return ctx, sdkerrors.Wrapf(sdkerrors.ErrUnknownRequest, "invalid message type %T, expected %T", msg, (*evmtypes.MsgEthereumTx)(nil))
		}

		allowUnprotectedTxs := esvd.evmKeeper.GetAllowUnprotectedTxs(ctx)
		ethTx := msgEthTx.AsTransaction()
		if !allowUnprotectedTxs && !ethTx.Protected() {
			return ctx, sdkerrors.Wrapf(
				sdkerrors.ErrNotSupported,
				"rejected unprotected Ethereum txs. Please EIP155 sign your transaction to protect it against replay-attacks")
		}

		sender, err := signer.Sender(ethTx)
		if err != nil {
			return ctx, sdkerrors.Wrapf(
				sdkerrors.ErrorInvalidSigner,
				"couldn't retrieve sender address from the ethereum transaction: %s",
				err.Error(),
			)
		}

		// set up the sender to the transaction field if not already
		msgEthTx.From = sender.Hex()
	}

	return next(ctx, tx, simulate)
}

// EthAccountVerificationDecorator validates an account balance checks
type EthAccountVerificationDecorator struct {
	ak        evmtypes.AccountKeeper
	evmKeeper EVMKeeper
}

// NewEthAccountVerificationDecorator creates a new EthAccountVerificationDecorator
func NewEthAccountVerificationDecorator(ak evmtypes.AccountKeeper, ek EVMKeeper) EthAccountVerificationDecorator {
	return EthAccountVerificationDecorator{
		ak:        ak,
		evmKeeper: ek,
	}
}

// AnteHandle validates checks that the sender balance is greater than the total transaction cost.
// The account will be set to store if it doesn't exis, i.e cannot be found on store.
// This AnteHandler decorator will fail if:
// - any of the msgs is not a MsgEthereumTx
// - from address is empty
// - account balance is lower than the transaction cost
func (avd EthAccountVerificationDecorator) AnteHandle(
	ctx sdk.Context,
	tx sdk.Tx,
	simulate bool,
	next sdk.AnteHandler,
) (newCtx sdk.Context, err error) {
	if !ctx.IsCheckTx() {
		return next(ctx, tx, simulate)
	}

	for i, msg := range tx.GetMsgs() {
		msgEthTx, ok := msg.(*evmtypes.MsgEthereumTx)
		if !ok {
			return ctx, sdkerrors.Wrapf(sdkerrors.ErrUnknownRequest, "invalid message type %T, expected %T", msg, (*evmtypes.MsgEthereumTx)(nil))
		}

		txData, err := evmtypes.UnpackTxData(msgEthTx.Data)
		if err != nil {
			return ctx, sdkerrors.Wrapf(err, "failed to unpack tx data any for tx %d", i)
		}

		// sender address should be in the tx cache from the previous AnteHandle call
		from := msgEthTx.GetFrom()
		if from.Empty() {
			return ctx, sdkerrors.Wrap(sdkerrors.ErrInvalidAddress, "from address cannot be empty")
		}

		// check whether the sender address is EOA
		fromAddr := common.BytesToAddress(from)
		acct := avd.evmKeeper.GetAccount(ctx, fromAddr)

		if acct == nil {
			acc := avd.ak.NewAccountWithAddress(ctx, from)
			avd.ak.SetAccount(ctx, acc)
			acct = statedb.NewEmptyAccount()
		} else if acct.IsContract() {
			return ctx, sdkerrors.Wrapf(sdkerrors.ErrInvalidType,
				"the sender is not EOA: address %s, codeHash <%s>", fromAddr, acct.CodeHash)
		}

		if err := evmkeeper.CheckSenderBalance(sdkmath.NewIntFromBigInt(acct.Balance), txData); err != nil {
			return ctx, sdkerrors.Wrap(err, "failed to check sender balance")
		}
	}
	return next(ctx, tx, simulate)
}

// EthGasConsumeDecorator validates enough intrinsic gas for the transaction and
// gas consumption.
type EthGasConsumeDecorator struct {
	evmKeeper    EVMKeeper
	maxGasWanted uint64
}

// NewEthGasConsumeDecorator creates a new EthGasConsumeDecorator
func NewEthGasConsumeDecorator(
	evmKeeper EVMKeeper,
	maxGasWanted uint64,
) EthGasConsumeDecorator {
	return EthGasConsumeDecorator{
		evmKeeper,
		maxGasWanted,
	}
}

// AnteHandle validates that the Ethereum tx message has enough to cover intrinsic gas
// (during CheckTx only) and that the sender has enough balance to pay for the gas cost.
//
// Intrinsic gas for a transaction is the amount of gas that the transaction uses before the
// transaction is executed. The gas is a constant value plus any cost incurred by additional bytes
// of data supplied with the transaction.
//
// This AnteHandler decorator will fail if:
// - the message is not a MsgEthereumTx
// - sender account cannot be found
// - transaction's gas limit is lower than the intrinsic gas
// - user doesn't have enough balance to deduct the transaction fees (gas_limit * gas_price)
// - transaction or block gas meter runs out of gas
// - sets the gas meter limit
// - gas limit is greater than the block gas meter limit
func (egcd EthGasConsumeDecorator) AnteHandle(ctx sdk.Context, tx sdk.Tx, simulate bool, next sdk.AnteHandler) (sdk.Context, error) {
	// gas consumption limit already checked during CheckTx so there's no need to
	// verify it again during ReCheckTx
	if ctx.IsReCheckTx() {
		return next(ctx, tx, simulate)
	}

	chainCfg := egcd.evmKeeper.GetChainConfig(ctx)
	ethCfg := chainCfg.EthereumConfig(egcd.evmKeeper.ChainID())

	blockHeight := big.NewInt(ctx.BlockHeight())
	homestead := ethCfg.IsHomestead(blockHeight)
	istanbul := ethCfg.IsIstanbul(blockHeight)
	london := ethCfg.IsLondon(blockHeight)
	gasWanted := uint64(0)
	var events sdk.Events

	// Use the lowest priority of all the messages as the final one.
	minPriority := int64(math.MaxInt64)

	for _, msg := range tx.GetMsgs() {
		msgEthTx, ok := msg.(*evmtypes.MsgEthereumTx)
		if !ok {
			return ctx, sdkerrors.Wrapf(sdkerrors.ErrUnknownRequest, "invalid message type %T, expected %T", msg, (*evmtypes.MsgEthereumTx)(nil))
		}

		txData, err := evmtypes.UnpackTxData(msgEthTx.Data)
		if err != nil {
			return ctx, sdkerrors.Wrap(err, "failed to unpack tx data")
		}

		if ctx.IsCheckTx() && egcd.maxGasWanted != 0 {
			// We can't trust the tx gas limit, because we'll refund the unused gas.
			if txData.GetGas() > egcd.maxGasWanted {
				gasWanted += egcd.maxGasWanted
			} else {
				gasWanted += txData.GetGas()
			}
		} else {
			gasWanted += txData.GetGas()
		}

		evmDenom := egcd.evmKeeper.GetEVMDenom(ctx)
		fees, priority, err := egcd.evmKeeper.DeductTxCostsFromUserBalance(
			ctx,
			*msgEthTx,
			txData,
			evmDenom,
			homestead,
			istanbul,
			london,
		)
		if err != nil {
			return ctx, sdkerrors.Wrapf(err, "failed to deduct transaction costs from user balance")
		}

		events = append(events,
			sdk.NewEvent(
				sdk.EventTypeTx,
				sdk.NewAttribute(sdk.AttributeKeyFee, fees.String()),
			),
		)

		if priority < minPriority {
			minPriority = priority
		}
	}

	ctx.EventManager().EmitEvents(events)

	blockGasLimit := ethermint.BlockGasLimit(ctx)

	// return error if the tx gas is greater than the block limit (max gas)

	// NOTE: it's important here to use the gas wanted instead of the gas consumed
	// from the tx gas pool. The later only has the value so far since the
	// EthSetupContextDecorator so it will never exceed the block gas limit.
	if gasWanted > blockGasLimit {
		return ctx, sdkerrors.Wrapf(
			sdkerrors.ErrOutOfGas,
			"tx gas (%d) exceeds block gas limit (%d)",
			gasWanted,
			blockGasLimit,
		)
	}

	// Set tx GasMeter with a limit of GasWanted (i.e gas limit from the Ethereum tx).
	// The gas consumed will be then reset to the gas used by the state transition
	// in the EVM.

	// FIXME: use a custom gas configuration that doesn't add any additional gas and only
	// takes into account the gas consumed at the end of the EVM transaction.
	newCtx := ctx.
		WithGasMeter(ethermint.NewInfiniteGasMeterWithLimit(gasWanted)).
		WithPriority(minPriority)

	// we know that we have enough gas on the pool to cover the intrinsic gas
	return next(newCtx, tx, simulate)
}

// CanTransferDecorator checks if the sender is allowed to transfer funds according to the EVM block
// context rules.
type CanTransferDecorator struct {
	evmKeeper EVMKeeper
}

// NewCanTransferDecorator creates a new CanTransferDecorator instance.
func NewCanTransferDecorator(evmKeeper EVMKeeper) CanTransferDecorator {
	return CanTransferDecorator{
		evmKeeper: evmKeeper,
	}
}

// AnteHandle creates an EVM from the message and calls the BlockContext CanTransfer function to
// see if the address can execute the transaction.
func (ctd CanTransferDecorator) AnteHandle(ctx sdk.Context, tx sdk.Tx, simulate bool, next sdk.AnteHandler) (sdk.Context, error) {
	params := ctd.evmKeeper.GetParams(ctx)
	ethCfg := params.ChainConfig.EthereumConfig(ctd.evmKeeper.ChainID())
	signer := ethtypes.MakeSigner(ethCfg, big.NewInt(ctx.BlockHeight()))

	for _, msg := range tx.GetMsgs() {
		msgEthTx, ok := msg.(*evmtypes.MsgEthereumTx)
		if !ok {
			return ctx, sdkerrors.Wrapf(sdkerrors.ErrUnknownRequest, "invalid message type %T, expected %T", msg, (*evmtypes.MsgEthereumTx)(nil))
		}

		baseFee := ctd.evmKeeper.GetBaseFee(ctx, ethCfg)

		coreMsg, err := msgEthTx.AsMessage(signer, baseFee)
		if err != nil {
			return ctx, sdkerrors.Wrapf(
				err,
				"failed to create an ethereum core.Message from signer %T", signer,
			)
		}

		if evmtypes.IsLondon(ethCfg, ctx.BlockHeight()) {
			if baseFee == nil {
				return ctx, sdkerrors.Wrap(
					evmtypes.ErrInvalidBaseFee,
					"base fee is supported but evm block context value is nil",
				)
			}
			if coreMsg.GasFeeCap().Cmp(baseFee) < 0 {
				return ctx, sdkerrors.Wrapf(
					sdkerrors.ErrInsufficientFee,
					"max fee per gas less than block base fee (%s < %s)",
					coreMsg.GasFeeCap(), baseFee,
				)
			}
		}

		// NOTE: pass in an empty coinbase address and nil tracer as we don't need them for the check below
		cfg := &evmtypes.EVMConfig{
			ChainConfig: ethCfg,
			Params:      params,
			CoinBase:    common.Address{},
			BaseFee:     baseFee,
		}
		stateDB := statedb.New(ctx, ctd.evmKeeper, statedb.NewEmptyTxConfig(common.BytesToHash(ctx.HeaderHash().Bytes())))
		evm := ctd.evmKeeper.NewEVM(ctx, coreMsg, cfg, evmtypes.NewNoOpTracer(), stateDB)

		// check that caller has enough balance to cover asset transfer for **topmost** call
		// NOTE: here the gas consumed is from the context with the infinite gas meter
		if coreMsg.Value().Sign() > 0 && !evm.Context().CanTransfer(stateDB, coreMsg.From(), coreMsg.Value()) {
			return ctx, sdkerrors.Wrapf(
				sdkerrors.ErrInsufficientFunds,
				"failed to transfer %s from address %s using the EVM block context transfer function",
				coreMsg.Value(),
				coreMsg.From(),
			)
		}
	}

	return next(ctx, tx, simulate)
}

// EthIncrementSenderSequenceDecorator increments the sequence of the signers.
type EthIncrementSenderSequenceDecorator struct {
	ak evmtypes.AccountKeeper
}

// NewEthIncrementSenderSequenceDecorator creates a new EthIncrementSenderSequenceDecorator.
func NewEthIncrementSenderSequenceDecorator(ak evmtypes.AccountKeeper) EthIncrementSenderSequenceDecorator {
	return EthIncrementSenderSequenceDecorator{
		ak: ak,
	}
}

// AnteHandle handles incrementing the sequence of the signer (i.e sender). If the transaction is a
// contract creation, the nonce will be incremented during the transaction execution and not within
// this AnteHandler decorator.
func (issd EthIncrementSenderSequenceDecorator) AnteHandle(ctx sdk.Context, tx sdk.Tx, simulate bool, next sdk.AnteHandler) (sdk.Context, error) {
	for _, msg := range tx.GetMsgs() {
		msgEthTx, ok := msg.(*evmtypes.MsgEthereumTx)
		if !ok {
			return ctx, sdkerrors.Wrapf(sdkerrors.ErrUnknownRequest, "invalid message type %T, expected %T", msg, (*evmtypes.MsgEthereumTx)(nil))
		}

		txData, err := evmtypes.UnpackTxData(msgEthTx.Data)
		if err != nil {
			return ctx, sdkerrors.Wrap(err, "failed to unpack tx data")
		}

		// increase sequence of sender
		acc := issd.ak.GetAccount(ctx, msgEthTx.GetFrom())
		if acc == nil {
			return ctx, sdkerrors.Wrapf(
				sdkerrors.ErrUnknownAddress,
				"account %s is nil", common.BytesToAddress(msgEthTx.GetFrom().Bytes()),
			)
		}
		nonce := acc.GetSequence()

		// we merged the nonce verification to nonce increment, so when tx includes multiple messages
		// with same sender, they'll be accepted.
		if txData.GetNonce() != nonce {
			return ctx, sdkerrors.Wrapf(
				sdkerrors.ErrInvalidSequence,
				"invalid nonce; got %d, expected %d", txData.GetNonce(), nonce,
			)
		}

		if err := acc.SetSequence(nonce + 1); err != nil {
			return ctx, sdkerrors.Wrapf(err, "failed to set sequence to %d", acc.GetSequence()+1)
		}

		issd.ak.SetAccount(ctx, acc)
	}

	return next(ctx, tx, simulate)
}

// EthValidateBasicDecorator is adapted from ValidateBasicDecorator from cosmos-sdk, it ignores ErrNoSignatures
type EthValidateBasicDecorator struct {
	evmKeeper EVMKeeper
}

// NewEthValidateBasicDecorator creates a new EthValidateBasicDecorator
func NewEthValidateBasicDecorator(ek EVMKeeper) EthValidateBasicDecorator {
	return EthValidateBasicDecorator{
		evmKeeper: ek,
	}
}

// AnteHandle handles basic validation of tx
func (vbd EthValidateBasicDecorator) AnteHandle(ctx sdk.Context, tx sdk.Tx, simulate bool, next sdk.AnteHandler) (sdk.Context, error) {
	// no need to validate basic on recheck tx, call next antehandler
	if ctx.IsReCheckTx() {
		return next(ctx, tx, simulate)
	}

	err := tx.ValidateBasic()
	// ErrNoSignatures is fine with eth tx
	if err != nil && !errors.Is(err, sdkerrors.ErrNoSignatures) {
		return ctx, sdkerrors.Wrap(err, "tx basic validation failed")
	}

	// For eth type cosmos tx, some fields should be veified as zero values,
	// since we will only verify the signature against the hash of the MsgEthereumTx.Data
	wrapperTx, ok := tx.(protoTxProvider)
	if !ok {
		return ctx, sdkerrors.Wrapf(sdkerrors.ErrUnknownRequest, "invalid tx type %T, didn't implement interface protoTxProvider", tx)
	}

	protoTx := wrapperTx.GetProtoTx()
	body := protoTx.Body
	if body.Memo != "" || body.TimeoutHeight != uint64(0) || len(body.NonCriticalExtensionOptions) > 0 {
		return ctx, sdkerrors.Wrap(sdkerrors.ErrInvalidRequest,
			"for eth tx body Memo TimeoutHeight NonCriticalExtensionOptions should be empty")
	}

	if len(body.ExtensionOptions) != 1 {
		return ctx, sdkerrors.Wrap(sdkerrors.ErrInvalidRequest, "for eth tx length of ExtensionOptions should be 1")
	}

	txFee := sdk.Coins{}
	txGasLimit := uint64(0)

	chainCfg := vbd.evmKeeper.GetChainConfig(ctx)
	chainID := vbd.evmKeeper.ChainID()
	ethCfg := chainCfg.EthereumConfig(chainID)
	baseFee := vbd.evmKeeper.GetBaseFee(ctx, ethCfg)
	enableCreate := vbd.evmKeeper.GetEnableCreate(ctx)
	enableCall := vbd.evmKeeper.GetEnableCall(ctx)
	evmDenom := vbd.evmKeeper.GetEVMDenom(ctx)

	for _, msg := range protoTx.GetMsgs() {
		msgEthTx, ok := msg.(*evmtypes.MsgEthereumTx)
		if !ok {
			return ctx, sdkerrors.Wrapf(sdkerrors.ErrUnknownRequest, "invalid message type %T, expected %T", msg, (*evmtypes.MsgEthereumTx)(nil))
		}

		// Validate `From` field
		if msgEthTx.From != "" {
			return ctx, sdkerrors.Wrapf(sdkerrors.ErrInvalidRequest, "invalid From %s, expect empty string", msgEthTx.From)
		}

		txGasLimit += msgEthTx.GetGas()

		txData, err := evmtypes.UnpackTxData(msgEthTx.Data)
		if err != nil {
			return ctx, sdkerrors.Wrap(err, "failed to unpack MsgEthereumTx Data")
		}

		// return error if contract creation or call are disabled through governance
		if !enableCreate && txData.GetTo() == nil {
			return ctx, sdkerrors.Wrap(evmtypes.ErrCreateDisabled, "failed to create new contract")
		} else if !enableCall && txData.GetTo() != nil {
			return ctx, sdkerrors.Wrap(evmtypes.ErrCallDisabled, "failed to call contract")
		}

		if baseFee == nil && txData.TxType() == ethtypes.DynamicFeeTxType {
			return ctx, sdkerrors.Wrap(ethtypes.ErrTxTypeNotSupported, "dynamic fee tx not supported")
		}

		txFee = txFee.Add(sdk.NewCoin(evmDenom, sdkmath.NewIntFromBigInt(txData.Fee())))
	}

	authInfo := protoTx.AuthInfo
	if len(authInfo.SignerInfos) > 0 {
		return ctx, sdkerrors.Wrap(sdkerrors.ErrInvalidRequest, "for eth tx AuthInfo SignerInfos should be empty")
	}

	if authInfo.Fee.Payer != "" || authInfo.Fee.Granter != "" {
		return ctx, sdkerrors.Wrap(sdkerrors.ErrInvalidRequest, "for eth tx AuthInfo Fee payer and granter should be empty")
	}

	if !authInfo.Fee.Amount.IsEqual(txFee) {
		return ctx, sdkerrors.Wrapf(sdkerrors.ErrInvalidRequest, "invalid AuthInfo Fee Amount (%s != %s)", authInfo.Fee.Amount, txFee)
	}

	if authInfo.Fee.GasLimit != txGasLimit {
		return ctx, sdkerrors.Wrapf(sdkerrors.ErrInvalidRequest, "invalid AuthInfo Fee GasLimit (%d != %d)", authInfo.Fee.GasLimit, txGasLimit)
	}

	sigs := protoTx.Signatures
	if len(sigs) > 0 {
		return ctx, sdkerrors.Wrap(sdkerrors.ErrInvalidRequest, "for eth tx Signatures should be empty")
	}

	return next(ctx, tx, simulate)
}

// EthSetupContextDecorator is adapted from SetUpContextDecorator from cosmos-sdk, it ignores gas consumption
// by setting the gas meter to infinite
type EthSetupContextDecorator struct {
	evmKeeper EVMKeeper
}

func NewEthSetUpContextDecorator(evmKeeper EVMKeeper) EthSetupContextDecorator {
	return EthSetupContextDecorator{
		evmKeeper: evmKeeper,
	}
}

func (esc EthSetupContextDecorator) AnteHandle(ctx sdk.Context, tx sdk.Tx, simulate bool, next sdk.AnteHandler) (newCtx sdk.Context, err error) {
	// all transactions must implement GasTx
	_, ok := tx.(authante.GasTx)
	if !ok {
		return newCtx, sdkerrors.Wrap(sdkerrors.ErrTxDecode, "Tx must be GasTx")
	}

	// We need to setup an empty gas config so that the gas is consistent with Ethereum.
	newCtx = ctx.WithGasMeter(sdk.NewInfiniteGasMeter()).
		WithKVGasConfig(storetypes.GasConfig{}).
		WithTransientKVGasConfig(storetypes.GasConfig{})

	// Reset transient gas used to prepare the execution of current cosmos tx.
	// Transient gas-used is necessary to sum the gas-used of cosmos tx, when it contains multiple eth msgs.
	esc.evmKeeper.ResetTransientGasUsed(ctx)
	return next(newCtx, tx, simulate)
}

// EthMempoolFeeDecorator will check if the transaction's effective fee is at least as large
// as the local validator's minimum gasFee (defined in validator config).
// If fee is too low, decorator returns error and tx is rejected from mempool.
// Note this only applies when ctx.CheckTx = true
// If fee is high enough or not CheckTx, then call next AnteHandler
// CONTRACT: Tx must implement FeeTx to use MempoolFeeDecorator
type EthMempoolFeeDecorator struct {
	evmKeeper EVMKeeper
}

func NewEthMempoolFeeDecorator(ek EVMKeeper) EthMempoolFeeDecorator {
	return EthMempoolFeeDecorator{
		evmKeeper: ek,
	}
}

// AnteHandle ensures that the provided fees meet a minimum threshold for the validator.
// This check only for local mempool purposes, and thus it is only run on (Re)CheckTx.
// The logic is also skipped if the London hard fork and EIP-1559 are enabled.
func (mfd EthMempoolFeeDecorator) AnteHandle(ctx sdk.Context, tx sdk.Tx, simulate bool, next sdk.AnteHandler) (newCtx sdk.Context, err error) {
	if !ctx.IsCheckTx() || simulate {
		return next(ctx, tx, simulate)
	}
	chainCfg := mfd.evmKeeper.GetChainConfig(ctx)
	ethCfg := chainCfg.EthereumConfig(mfd.evmKeeper.ChainID())

	baseFee := mfd.evmKeeper.GetBaseFee(ctx, ethCfg)
	// skip check as the London hard fork and EIP-1559 are enabled
	if baseFee != nil {
		return next(ctx, tx, simulate)
	}

	evmDenom := mfd.evmKeeper.GetEVMDenom(ctx)
	minGasPrice := ctx.MinGasPrices().AmountOf(evmDenom)

	for _, msg := range tx.GetMsgs() {
		ethMsg, ok := msg.(*evmtypes.MsgEthereumTx)
		if !ok {
			return ctx, sdkerrors.Wrapf(sdkerrors.ErrUnknownRequest, "invalid message type %T, expected %T", msg, (*evmtypes.MsgEthereumTx)(nil))
		}

		fee := sdk.NewDecFromBigInt(ethMsg.GetFee())
		gasLimit := sdk.NewDecFromBigInt(new(big.Int).SetUint64(ethMsg.GetGas()))
		requiredFee := minGasPrice.Mul(gasLimit)

		if fee.LT(requiredFee) {
			return ctx, sdkerrors.Wrapf(
				sdkerrors.ErrInsufficientFee,
				"insufficient fees; got: %s required: %s",
				fee, requiredFee,
			)
		}
	}

	return next(ctx, tx, simulate)
}

// EthEmitEventDecorator emit events in ante handler in case of tx execution failed (out of block gas limit).
type EthEmitEventDecorator struct {
	evmKeeper EVMKeeper
}

// NewEthEmitEventDecorator creates a new EthEmitEventDecorator
func NewEthEmitEventDecorator(evmKeeper EVMKeeper) EthEmitEventDecorator {
	return EthEmitEventDecorator{evmKeeper}
}

// AnteHandle emits some basic events for the eth messages
func (eeed EthEmitEventDecorator) AnteHandle(ctx sdk.Context, tx sdk.Tx, simulate bool, next sdk.AnteHandler) (newCtx sdk.Context, err error) {
	// After eth tx passed ante handler, the fee is deducted and nonce increased, it shouldn't be ignored by json-rpc,
	// we need to emit some basic events at the very end of ante handler to be indexed by tendermint.
	txIndex := eeed.evmKeeper.GetTxIndexTransient(ctx)
	for i, msg := range tx.GetMsgs() {
		msgEthTx, ok := msg.(*evmtypes.MsgEthereumTx)
		if !ok {
			return ctx, sdkerrors.Wrapf(sdkerrors.ErrUnknownRequest, "invalid message type %T, expected %T", msg, (*evmtypes.MsgEthereumTx)(nil))
		}

		// emit ethereum tx hash as event, should be indexed by tm tx indexer for query purpose.
		// it's emitted in ante handler so we can query failed transaction (out of block gas limit).
		ctx.EventManager().EmitEvent(sdk.NewEvent(
			evmtypes.EventTypeEthereumTx,
			sdk.NewAttribute(evmtypes.AttributeKeyEthereumTxHash, msgEthTx.Hash),
			sdk.NewAttribute(evmtypes.AttributeKeyTxIndex, strconv.FormatUint(txIndex+uint64(i), 10)),
		))
	}

	return next(ctx, tx, simulate)
}