package ante

import (
	"fmt"

	"github.com/cosmos/cosmos-sdk/crypto/keys/ed25519"
	"github.com/cosmos/cosmos-sdk/crypto/keys/secp256k1"
	"github.com/cosmos/cosmos-sdk/crypto/types/multisig"
	sdk "github.com/cosmos/cosmos-sdk/types"
	sdkerrors "github.com/cosmos/cosmos-sdk/types/errors"
	"github.com/cosmos/cosmos-sdk/types/tx/signing"
	authante "github.com/cosmos/cosmos-sdk/x/auth/ante"
	authsigning "github.com/cosmos/cosmos-sdk/x/auth/signing"
	authtypes "github.com/cosmos/cosmos-sdk/x/auth/types"

	"github.com/cosmos/ethermint/crypto/ethsecp256k1"
	evmtypes "github.com/cosmos/ethermint/x/evm/types"
)

const (
	// TODO: Use this cost per byte through parameter or overriding NewConsumeGasForTxSizeDecorator
	// which currently defaults at 10, if intended
	// memoCostPerByte     sdk.Gas = 3
	secp256k1VerifyCost uint64 = 21000
)

// AccountKeeper defines an expected keeper interface for the auth module's AccountKeeper
type AccountKeeper interface {
	authante.AccountKeeper
	NewAccountWithAddress(ctx sdk.Context, addr sdk.AccAddress) authtypes.AccountI
}

// BankKeeper defines an expected keeper interface for the bank module's Keeper
type BankKeeper interface {
	authtypes.BankKeeper
	GetBalance(ctx sdk.Context, addr sdk.AccAddress, denom string) sdk.Coin
	SetBalance(ctx sdk.Context, addr sdk.AccAddress, balance sdk.Coin) error
}

// NewAnteHandler returns an ante handler responsible for attempting to route an
// Ethereum or SDK transaction to an internal ante handler for performing
// transaction-level processing (e.g. fee payment, signature verification) before
// being passed onto it's respective handler.
func NewAnteHandler(
	ak AccountKeeper, bankKeeper BankKeeper, evmKeeper EVMKeeper, signModeHandler authsigning.SignModeHandler,
) sdk.AnteHandler {
	return func(
		ctx sdk.Context, tx sdk.Tx, sim bool,
	) (newCtx sdk.Context, err error) {
		var anteHandler sdk.AnteHandler
		switch tx.(type) {
		case *evmtypes.MsgEthereumTx:
			anteHandler = sdk.ChainAnteDecorators(
				NewEthSetupContextDecorator(), // outermost AnteDecorator. EthSetUpContext must be called first
				authante.NewRejectExtensionOptionsDecorator(),
				NewEthMempoolFeeDecorator(evmKeeper),
				authante.NewValidateBasicDecorator(),
				NewEthSigVerificationDecorator(),
				NewAccountVerificationDecorator(ak, bankKeeper, evmKeeper),
				NewNonceVerificationDecorator(ak),
				NewEthGasConsumeDecorator(ak, bankKeeper, evmKeeper),
				NewIncrementSenderSequenceDecorator(ak), // innermost AnteDecorator.
			)

		case sdk.Tx:
			anteHandler = sdk.ChainAnteDecorators(
				authante.NewSetUpContextDecorator(), // outermost AnteDecorator. SetUpContext must be called first
				authante.NewRejectExtensionOptionsDecorator(),
				authante.NewMempoolFeeDecorator(),
				authante.NewValidateBasicDecorator(),
				authante.TxTimeoutHeightDecorator{},
				authante.NewValidateMemoDecorator(ak),
				authante.NewConsumeGasForTxSizeDecorator(ak),
				authante.NewRejectFeeGranterDecorator(),
				authante.NewSetPubKeyDecorator(ak), // SetPubKeyDecorator must be called before all signature verification decorators
				authante.NewValidateSigCountDecorator(ak),
				authante.NewDeductFeeDecorator(ak, bankKeeper),
				authante.NewSigGasConsumeDecorator(ak, DefaultSigVerificationGasConsumer),
				authante.NewSigVerificationDecorator(ak, signModeHandler),
				authante.NewIncrementSequenceDecorator(ak), // innermost AnteDecorator
			)
		default:
			return ctx, sdkerrors.Wrapf(sdkerrors.ErrUnknownRequest, "invalid transaction type: %T", tx)
		}

		return anteHandler(ctx, tx, sim)
	}
}

var _ = DefaultSigVerificationGasConsumer

// DefaultSigVerificationGasConsumer is the default implementation of SignatureVerificationGasConsumer. It consumes gas
// for signature verification based upon the public key type. The cost is fetched from the given params and is matched
// by the concrete type.
func DefaultSigVerificationGasConsumer(
	meter sdk.GasMeter, sig signing.SignatureV2, params authtypes.Params,
) error {
	pubkey := sig.PubKey
	switch pubkey := pubkey.(type) {
	case *ed25519.PubKey:
		meter.ConsumeGas(params.SigVerifyCostED25519, "ante verify: ed25519")
		return nil

	case *secp256k1.PubKey:
		meter.ConsumeGas(params.SigVerifyCostSecp256k1, "ante verify: secp256k1")
		return nil

	// support for etherum ECDSA secp256k1 keys
	case *ethsecp256k1.PubKey:
		meter.ConsumeGas(secp256k1VerifyCost, "ante verify: eth_secp256k1")
		return nil

	case multisig.PubKey:
		multisignature, ok := sig.Data.(*signing.MultiSignatureData)
		if !ok {
			return fmt.Errorf("expected %T, got, %T", &signing.MultiSignatureData{}, sig.Data)
		}
		err := authante.ConsumeMultisignatureVerificationGas(meter, multisignature, pubkey, params, sig.Sequence)
		if err != nil {
			return err
		}
		return nil
	default:
		return sdkerrors.Wrapf(sdkerrors.ErrInvalidPubKey, "unrecognized public key type: %T", pubkey)
	}
}