mev-beta/pkg/contracts/executor.go

// Package contracts provides integration with MEV smart contracts for arbitrage execution
package contracts

import (
	"context"
	"fmt"
	"math/big"
	"time"

	"github.com/ethereum/go-ethereum/accounts/abi/bind"
	"github.com/ethereum/go-ethereum/common"
	etypes "github.com/ethereum/go-ethereum/core/types"
	"github.com/ethereum/go-ethereum/ethclient"
	"github.com/fraktal/mev-beta/bindings/arbitrage"
	"github.com/fraktal/mev-beta/bindings/flashswap"
	"github.com/fraktal/mev-beta/bindings/interfaces"
	"github.com/fraktal/mev-beta/internal/config"
	"github.com/fraktal/mev-beta/internal/logger"
	stypes "github.com/fraktal/mev-beta/pkg/types"
)

// ContractExecutor handles execution of arbitrage opportunities through smart contracts
type ContractExecutor struct {
	config          *config.BotConfig
	logger          *logger.Logger
	client          *ethclient.Client
	arbitrage       *arbitrage.ArbitrageExecutor
	flashSwapper    *flashswap.BaseFlashSwapper
	privateKey      string
	accountAddress  common.Address
	chainID         *big.Int
	gasPrice        *big.Int
	pendingNonce    uint64
	lastNonceUpdate time.Time
}

// NewContractExecutor creates a new contract executor
func NewContractExecutor(
	cfg *config.Config,
	logger *logger.Logger,
) (*ContractExecutor, error) {
	// Connect to Ethereum client
	client, err := ethclient.Dial(cfg.Arbitrum.RPCEndpoint)
	if err != nil {
		return nil, fmt.Errorf("failed to connect to Ethereum node: %w", err)
	}

	// Parse contract addresses from config
	arbitrageAddr := common.HexToAddress(cfg.Contracts.ArbitrageExecutor)
	flashSwapperAddr := common.HexToAddress(cfg.Contracts.FlashSwapper)

	// Create contract instances
	arbitrageContract, err := arbitrage.NewArbitrageExecutor(arbitrageAddr, client)
	if err != nil {
		return nil, fmt.Errorf("failed to instantiate arbitrage contract: %w", err)
	}

	flashSwapperContract, err := flashswap.NewBaseFlashSwapper(flashSwapperAddr, client)
	if err != nil {
		return nil, fmt.Errorf("failed to instantiate flash swapper contract: %w", err)
	}

	// Get chain ID
	chainID, err := client.ChainID(context.Background())
	if err != nil {
		return nil, fmt.Errorf("failed to get chain ID: %w", err)
	}

	executor := &ContractExecutor{
		config:         &cfg.Bot,
		logger:         logger,
		client:         client,
		arbitrage:      arbitrageContract,
		flashSwapper:   flashSwapperContract,
		privateKey:     cfg.Ethereum.PrivateKey,
		accountAddress: common.HexToAddress(cfg.Ethereum.AccountAddress),
		chainID:        chainID,
		gasPrice:       big.NewInt(0),
		pendingNonce:   0,
	}

	// Initialize gas price
	if err := executor.updateGasPrice(); err != nil {
		logger.Warn(fmt.Sprintf("Failed to initialize gas price: %v", err))
	}

	logger.Info("Contract executor initialized successfully")
	return executor, nil
}

// ExecuteArbitrage executes a standard arbitrage opportunity
func (ce *ContractExecutor) ExecuteArbitrage(ctx context.Context, opportunity stypes.ArbitrageOpportunity) (*etypes.Transaction, error) {
	ce.logger.Info(fmt.Sprintf("Executing arbitrage opportunity: %+v", opportunity))

	// Convert opportunity to contract parameters
	params := ce.convertToArbitrageParams(opportunity)

	// Prepare transaction options
	opts, err := ce.prepareTransactionOpts(ctx)
	if err != nil {
		return nil, fmt.Errorf("failed to prepare transaction options: %w", err)
	}

	// Execute arbitrage through contract
	tx, err := ce.arbitrage.ExecuteArbitrage(opts, params)
	if err != nil {
		return nil, fmt.Errorf("failed to execute arbitrage: %w", err)
	}

	ce.logger.Info(fmt.Sprintf("Arbitrage transaction submitted: %s", tx.Hash().Hex()))
	return tx, nil
}

// ExecuteTriangularArbitrage executes a triangular arbitrage opportunity
func (ce *ContractExecutor) ExecuteTriangularArbitrage(ctx context.Context, opportunity stypes.ArbitrageOpportunity) (*etypes.Transaction, error) {
	ce.logger.Info(fmt.Sprintf("Executing triangular arbitrage opportunity: %+v", opportunity))

	// Convert opportunity to contract parameters
	params := ce.convertToTriangularArbitrageParams(opportunity)

	// Prepare transaction options
	opts, err := ce.prepareTransactionOpts(ctx)
	if err != nil {
		return nil, fmt.Errorf("failed to prepare transaction options: %w", err)
	}

	// Execute triangular arbitrage through contract
	tx, err := ce.arbitrage.ExecuteTriangularArbitrage(opts, params)
	if err != nil {
		return nil, fmt.Errorf("failed to execute triangular arbitrage: %w", err)
	}

	ce.logger.Info(fmt.Sprintf("Triangular arbitrage transaction submitted: %s", tx.Hash().Hex()))
	return tx, nil
}

// convertToArbitrageParams converts a scanner opportunity to contract parameters
func (ce *ContractExecutor) convertToArbitrageParams(opportunity stypes.ArbitrageOpportunity) interfaces.IArbitrageArbitrageParams {
	// Convert token addresses
	tokens := make([]common.Address, len(opportunity.Path))
	for i, token := range opportunity.Path {
		tokens[i] = common.HexToAddress(token)
	}

	// Convert pool addresses
	pools := make([]common.Address, len(opportunity.Pools))
	for i, pool := range opportunity.Pools {
		pools[i] = common.HexToAddress(pool)
	}

	// Convert amounts (simplified for now)
	amounts := make([]*big.Int, len(pools))
	for i := range amounts {
		// Use a default amount for now - in practice this should be calculated based on optimal trade size
		amounts[i] = big.NewInt(1000000000000000000) // 1 ETH equivalent
	}

	// Convert swap data (empty for now - in practice this would contain encoded swap parameters)
	swapData := make([][]byte, len(pools))
	for i := range swapData {
		swapData[i] = []byte{}
	}

	// Create parameters struct
	params := interfaces.IArbitrageArbitrageParams{
		Tokens:    tokens,
		Pools:     pools,
		Amounts:   amounts,
		SwapData:  swapData,
		MinProfit: opportunity.Profit, // Use estimated profit as minimum required profit
	}

	return params
}

// convertToTriangularArbitrageParams converts a scanner opportunity to triangular arbitrage parameters
func (ce *ContractExecutor) convertToTriangularArbitrageParams(opportunity stypes.ArbitrageOpportunity) interfaces.IArbitrageTriangularArbitrageParams {
	// For triangular arbitrage, we expect exactly 3 tokens forming a triangle
	if len(opportunity.Path) < 3 {
		ce.logger.Error("Invalid triangular arbitrage path - insufficient tokens")
		return interfaces.IArbitrageTriangularArbitrageParams{}
	}

	// Extract the three tokens
	tokenA := common.HexToAddress(opportunity.Path[0])
	tokenB := common.HexToAddress(opportunity.Path[1])
	tokenC := common.HexToAddress(opportunity.Path[2])

	// Extract pools (should be 3 for triangular arbitrage)
	if len(opportunity.Pools) < 3 {
		ce.logger.Error("Invalid triangular arbitrage pools - insufficient pools")
		return interfaces.IArbitrageTriangularArbitrageParams{}
	}

	poolAB := common.HexToAddress(opportunity.Pools[0])
	poolBC := common.HexToAddress(opportunity.Pools[1])
	poolCA := common.HexToAddress(opportunity.Pools[2])

	// Create parameters struct
	params := interfaces.IArbitrageTriangularArbitrageParams{
		TokenA:     tokenA,
		TokenB:     tokenB,
		TokenC:     tokenC,
		PoolAB:     poolAB,
		PoolBC:     poolBC,
		PoolCA:     poolCA,
		AmountIn:   big.NewInt(1000000000000000000), // 1 ETH equivalent (placeholder)
		MinProfit:  opportunity.Profit,              // Use estimated profit as minimum required profit
		SwapDataAB: []byte{},                        // Placeholder for actual swap data
		SwapDataBC: []byte{},                        // Placeholder for actual swap data
		SwapDataCA: []byte{},                        // Placeholder for actual swap data
	}

	return params
}

// prepareTransactionOpts prepares transaction options with proper gas pricing and nonce
func (ce *ContractExecutor) prepareTransactionOpts(ctx context.Context) (*bind.TransactOpts, error) {
	// Update gas price if needed
	if err := ce.updateGasPrice(); err != nil {
		ce.logger.Warn(fmt.Sprintf("Failed to update gas price: %v", err))
	}

	// Get current nonce
	nonce, err := ce.client.PendingNonceAt(ctx, ce.accountAddress)
	if err != nil {
		return nil, fmt.Errorf("failed to get account nonce: %w", err)
	}

	// Create transaction options
	opts := &bind.TransactOpts{
		From:     ce.accountAddress,
		Nonce:    big.NewInt(int64(nonce)),
		Signer:   ce.signTransaction, // Custom signer function
		Value:    big.NewInt(0),      // No ETH value for arbitrage transactions
		GasPrice: ce.gasPrice,
		GasLimit: 0, // Let the node estimate gas limit
		Context:  ctx,
		NoSend:   false,
	}

	return opts, nil
}

// updateGasPrice updates the gas price estimate
func (ce *ContractExecutor) updateGasPrice() error {
	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
	defer cancel()

	// Get suggested gas price from node
	gasPrice, err := ce.client.SuggestGasPrice(ctx)
	if err != nil {
		return fmt.Errorf("failed to suggest gas price: %w", err)
	}

	// Apply gas price multiplier from config (if set)
	if ce.config.Ethereum.GasPriceMultiplier > 1.0 {
		multiplier := big.NewFloat(ce.config.Ethereum.GasPriceMultiplier)
		gasPriceFloat := new(big.Float).SetInt(gasPrice)
		adjustedGasPriceFloat := new(big.Float).Mul(gasPriceFloat, multiplier)
		adjustedGasPrice, _ := adjustedGasPriceFloat.Int(nil)
		ce.gasPrice = adjustedGasPrice
	} else {
		ce.gasPrice = gasPrice
	}

	return nil
}

// signTransaction signs a transaction with the configured private key
func (ce *ContractExecutor) signTransaction(address common.Address, tx *etypes.Transaction) (*etypes.Transaction, error) {
	// In a production implementation, you would use the private key to sign the transaction
	// For now, we'll return the transaction as-is since we're using the client's built-in signing
	ce.logger.Debug("Signing transaction (placeholder)")
	return tx, nil
}

// Close closes the contract executor and releases resources
func (ce *ContractExecutor) Close() {
	if ce.client != nil {
		ce.client.Close()
	}
}