package types

import (
	"fmt"
	"math/big"

	"github.com/cosmos/cosmos-sdk/crypto/keyring"
	sdk "github.com/cosmos/cosmos-sdk/types"
	sdkerrors "github.com/cosmos/cosmos-sdk/types/errors"
	"github.com/cosmos/cosmos-sdk/x/auth/ante"

	"github.com/tharsis/ethermint/types"

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

var (
	_ sdk.Msg    = &MsgEthereumTx{}
	_ sdk.Tx     = &MsgEthereumTx{}
	_ ante.GasTx = &MsgEthereumTx{}
)

// message type and route constants
const (
	// TypeMsgEthereumTx defines the type string of an Ethereum transaction
	TypeMsgEthereumTx = "ethereum_tx"
)

// NewMsgEthereumTx returns a reference to a new Ethereum transaction message.
func NewMsgEthereumTx(
	chainID *big.Int, nonce uint64, to *common.Address, amount *big.Int,
	gasLimit uint64, gasPrice *big.Int, input []byte, accesses *ethtypes.AccessList,
) *MsgEthereumTx {
	return newMsgEthereumTx(chainID, nonce, to, amount, gasLimit, gasPrice, input, accesses)
}

// NewMsgEthereumTxContract returns a reference to a new Ethereum transaction
// message designated for contract creation.
func NewMsgEthereumTxContract(
	chainID *big.Int, nonce uint64, amount *big.Int,
	gasLimit uint64, gasPrice *big.Int, input []byte, accesses *ethtypes.AccessList,
) *MsgEthereumTx {
	return newMsgEthereumTx(chainID, nonce, nil, amount, gasLimit, gasPrice, input, accesses)
}

func newMsgEthereumTx(
	chainID *big.Int, nonce uint64, to *common.Address, amount *big.Int,
	gasLimit uint64, gasPrice *big.Int, input []byte, accesses *ethtypes.AccessList,
) *MsgEthereumTx {
	txData := newTxData(chainID, nonce, to, amount, gasLimit, gasPrice, input, accesses)
	return &MsgEthereumTx{Data: txData}
}

// fromEthereumTx populates the message fields from the given ethereum transaction
func (msg *MsgEthereumTx) FromEthereumTx(tx *ethtypes.Transaction) {
	msg.Data = &TxData{
		Nonce:    tx.Nonce(),
		Input:    tx.Data(),
		GasLimit: tx.Gas(),
	}

	v, r, s := tx.RawSignatureValues()
	if tx.To() != nil {
		msg.Data.To = tx.To().Hex()
	}
	if tx.Value() != nil {
		msg.Data.Amount = tx.Value().Bytes()
	}
	if tx.GasPrice() != nil {
		msg.Data.GasPrice = tx.GasPrice().Bytes()
	}
	if tx.AccessList() != nil {
		al := tx.AccessList()
		msg.Data.Accesses = NewAccessList(&al)
	}

	msg.Data.setSignatureValues(tx.ChainId(), v, r, s)

	msg.Size_ = float64(tx.Size())
	msg.Hash = tx.Hash().Hex()
}

// Route returns the route value of an MsgEthereumTx.
func (msg MsgEthereumTx) Route() string { return RouterKey }

// Type returns the type value of an MsgEthereumTx.
func (msg MsgEthereumTx) Type() string { return TypeMsgEthereumTx }

// ValidateBasic implements the sdk.Msg interface. It performs basic validation
// checks of a Transaction. If returns an error if validation fails.
func (msg MsgEthereumTx) ValidateBasic() error {
	if msg.From != "" {
		if err := types.ValidateAddress(msg.From); err != nil {
			return sdkerrors.Wrap(err, "invalid from address")
		}
	}

	return msg.Data.Validate()
}

// To returns the recipient address of the transaction. It returns nil if the
// transaction is a contract creation.
func (msg MsgEthereumTx) To() *common.Address {
	return msg.Data.to()
}

// GetMsgs returns a single MsgEthereumTx as an sdk.Msg.
func (msg *MsgEthereumTx) GetMsgs() []sdk.Msg {
	return []sdk.Msg{msg}
}

// GetSigners returns the expected signers for an Ethereum transaction message.
// For such a message, there should exist only a single 'signer'.
//
// NOTE: This method panics if 'Sign' hasn't been called first.
func (msg MsgEthereumTx) GetSigners() []sdk.AccAddress {
	v, r, s := msg.RawSignatureValues()

	if msg.From == "" || v == nil || r == nil || s == nil {
		panic("must use 'Sign' to get the signer address")
	}

	signer := sdk.AccAddress(common.HexToAddress(msg.From).Bytes())
	return []sdk.AccAddress{signer}
}

// GetSignBytes returns the Amino bytes of an Ethereum transaction message used
// for signing.
//
// NOTE: This method cannot be used as a chain ID is needed to create valid bytes
// to sign over. Use 'RLPSignBytes' instead.
func (msg MsgEthereumTx) GetSignBytes() []byte {
	panic("must use 'RLPSignBytes' with a chain ID to get the valid bytes to sign")
}

// Sign calculates a secp256k1 ECDSA signature and signs the transaction. It
// takes a keyring signer and the chainID to sign an Ethereum transaction according to
// EIP155 standard.
// This method mutates the transaction as it populates the V, R, S
// fields of the Transaction's Signature.
// The function will fail if the sender address is not defined for the msg or if
// the sender is not registered on the keyring
func (msg *MsgEthereumTx) Sign(ethSigner ethtypes.Signer, keyringSigner keyring.Signer) error {
	from := msg.GetFrom()
	if from.Empty() {
		return fmt.Errorf("sender address not defined for message")
	}

	tx := msg.AsTransaction()
	txHash := ethSigner.Hash(tx)

	sig, _, err := keyringSigner.SignByAddress(from, txHash.Bytes())
	if err != nil {
		return err
	}

	tx, err = tx.WithSignature(ethSigner, sig)
	if err != nil {
		return err
	}

	msg.FromEthereumTx(tx)
	return nil
}

// GetGas implements the GasTx interface. It returns the GasLimit of the transaction.
func (msg MsgEthereumTx) GetGas() uint64 {
	return msg.Data.gas()
}

// Fee returns gasprice * gaslimit.
func (msg MsgEthereumTx) Fee() *big.Int {
	gasPrice := msg.Data.gasPrice()
	gasLimit := new(big.Int).SetUint64(msg.Data.gas())
	return new(big.Int).Mul(gasPrice, gasLimit)
}

// ChainID returns which chain id this transaction was signed for (if at all)
func (msg *MsgEthereumTx) ChainID() *big.Int {
	return msg.Data.chainID()
}

// Cost returns amount + gasprice * gaslimit.
func (msg MsgEthereumTx) Cost() *big.Int {
	total := msg.Fee()
	if msg.Data.amount() != nil {
		total.Add(total, msg.Data.amount())
	}
	return total
}

// RawSignatureValues returns the V, R, S signature values of the transaction.
// The return values should not be modified by the caller.
func (msg MsgEthereumTx) RawSignatureValues() (v, r, s *big.Int) {
	return msg.Data.rawSignatureValues()
}

// GetFrom loads the ethereum sender address from the sigcache and returns an
// sdk.AccAddress from its bytes
func (msg *MsgEthereumTx) GetFrom() sdk.AccAddress {
	if msg.From == "" {
		return nil
	}

	return common.HexToAddress(msg.From).Bytes()
}

// AsTransaction creates an Ethereum Transaction type from the msg fields
func (msg MsgEthereumTx) AsTransaction() *ethtypes.Transaction {
	return ethtypes.NewTx(msg.Data.AsEthereumData())
}

// AsMessage creates an Ethereum core.Message from the msg fields
func (msg MsgEthereumTx) AsMessage(signer ethtypes.Signer) (core.Message, error) {
	return msg.AsTransaction().AsMessage(signer)
}