mev-beta/pkg/execution/flashloan_providers.go

package execution

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

	"github.com/ethereum/go-ethereum/common"
	"github.com/ethereum/go-ethereum/ethclient"

	"github.com/fraktal/mev-beta/internal/logger"
	"github.com/fraktal/mev-beta/pkg/types"
)

// AaveFlashLoanProvider implements flash loans using Aave Protocol
type AaveFlashLoanProvider struct {
	client *ethclient.Client
	logger *logger.Logger

	// Aave V3 Pool contract on Arbitrum
	poolAddress common.Address
	fee         *big.Int // 0.09% fee = 9 basis points
}

// NewAaveFlashLoanProvider creates a new Aave flash loan provider
func NewAaveFlashLoanProvider(client *ethclient.Client, logger *logger.Logger) *AaveFlashLoanProvider {
	return &AaveFlashLoanProvider{
		client: client,
		logger: logger,
		// Aave V3 Pool on Arbitrum
		poolAddress: common.HexToAddress("0x794a61358D6845594F94dc1DB02A252b5b4814aD"),
		fee:         big.NewInt(9), // 0.09% = 9 basis points
	}
}

// ExecuteFlashLoan executes arbitrage using Aave flash loan
func (a *AaveFlashLoanProvider) ExecuteFlashLoan(
	ctx context.Context,
	opportunity *types.ArbitrageOpportunity,
	config *ExecutionConfig,
) (*ExecutionResult, error) {
	a.logger.Info(fmt.Sprintf("⚡ Executing Aave flash loan for %s ETH", opportunity.AmountIn.String()))

	// TODO: Implement actual Aave flash loan execution
	// Steps:
	// 1. Build flashLoan() calldata with:
	//    - Assets to borrow
	//    - Amounts
	//    - Modes (0 for no debt)
	//    - OnBehalfOf address
	//    - Params (encoded arbitrage path)
	//    - ReferralCode
	// 2. Send transaction to Aave Pool
	// 3. Wait for receipt
	// 4. Parse events and calculate actual profit

	return &ExecutionResult{
		OpportunityID:   opportunity.ID,
		Success:         false,
		Error:           fmt.Errorf("Aave flash loan execution not yet implemented"),
		EstimatedProfit: opportunity.NetProfit,
	}, fmt.Errorf("not implemented")
}

// GetMaxLoanAmount returns maximum borrowable amount from Aave
func (a *AaveFlashLoanProvider) GetMaxLoanAmount(ctx context.Context, token common.Address) (*big.Int, error) {
	// TODO: Query Aave reserves to get available liquidity
	// For now, return a large amount
	return new(big.Int).Mul(big.NewInt(1000), big.NewInt(1e18)), nil // 1000 ETH
}

// GetFee calculates Aave flash loan fee
func (a *AaveFlashLoanProvider) GetFee(ctx context.Context, amount *big.Int) (*big.Int, error) {
	// Aave V3 fee is 0.09% (9 basis points)
	fee := new(big.Int).Mul(amount, a.fee)
	fee = fee.Div(fee, big.NewInt(10000))
	return fee, nil
}

// SupportsToken checks if Aave supports the token
func (a *AaveFlashLoanProvider) SupportsToken(token common.Address) bool {
	// TODO: Query Aave reserves to check token support
	// For now, support common tokens
	supportedTokens := map[common.Address]bool{
		common.HexToAddress("0x82aF49447D8a07e3bd95BD0d56f35241523fBab1"): true, // WETH
		common.HexToAddress("0xaf88d065e77c8cC2239327C5EDb3A432268e5831"): true, // USDC
		common.HexToAddress("0xFd086bC7CD5C481DCC9C85ebE478A1C0b69FCbb9"): true, // USDT
		common.HexToAddress("0x2f2a2543B76A4166549F7aaB2e75Bef0aefC5B0f"): true, // WBTC
		common.HexToAddress("0xDA10009cBd5D07dd0CeCc66161FC93D7c9000da1"): true, // DAI
	}
	return supportedTokens[token]
}

// UniswapFlashLoanProvider implements flash swaps using Uniswap V2/V3
type UniswapFlashLoanProvider struct {
	client *ethclient.Client
	logger *logger.Logger
}

// NewUniswapFlashLoanProvider creates a new Uniswap flash swap provider
func NewUniswapFlashLoanProvider(client *ethclient.Client, logger *logger.Logger) *UniswapFlashLoanProvider {
	return &UniswapFlashLoanProvider{
		client: client,
		logger: logger,
	}
}

// ExecuteFlashLoan executes arbitrage using Uniswap flash swap
func (u *UniswapFlashLoanProvider) ExecuteFlashLoan(
	ctx context.Context,
	opportunity *types.ArbitrageOpportunity,
	config *ExecutionConfig,
) (*ExecutionResult, error) {
	u.logger.Info(fmt.Sprintf("⚡ Executing Uniswap flash swap for %s ETH", opportunity.AmountIn.String()))

	// TODO: Implement Uniswap V2/V3 flash swap
	// V2 Flash Swap:
	// 1. Call swap() on pair with amount0Out/amount1Out
	// 2. Implement uniswapV2Call callback
	// 3. Execute arbitrage in callback
	// 4. Repay loan + fee (0.3%)
	//
	// V3 Flash:
	// 1. Call flash() on pool
	// 2. Implement uniswapV3FlashCallback
	// 3. Execute arbitrage
	// 4. Repay exact amount

	return &ExecutionResult{
		OpportunityID:   opportunity.ID,
		Success:         false,
		Error:           fmt.Errorf("Uniswap flash swap execution not yet implemented"),
		EstimatedProfit: opportunity.NetProfit,
	}, fmt.Errorf("not implemented")
}

// GetMaxLoanAmount returns maximum borrowable from Uniswap pools
func (u *UniswapFlashLoanProvider) GetMaxLoanAmount(ctx context.Context, token common.Address) (*big.Int, error) {
	// TODO: Find pool with most liquidity for the token
	return new(big.Int).Mul(big.NewInt(100), big.NewInt(1e18)), nil // 100 ETH
}

// GetFee calculates Uniswap flash swap fee
func (u *UniswapFlashLoanProvider) GetFee(ctx context.Context, amount *big.Int) (*big.Int, error) {
	// V2 flash swap fee is same as trading fee (0.3%)
	// V3 fee depends on pool tier (0.05%, 0.3%, 1%)
	// Use 0.3% as default
	fee := new(big.Int).Mul(amount, big.NewInt(3))
	fee = fee.Div(fee, big.NewInt(1000))
	return fee, nil
}

// SupportsToken checks if Uniswap has pools for the token
func (u *UniswapFlashLoanProvider) SupportsToken(token common.Address) bool {
	// Uniswap supports most tokens via pools
	return true
}

// BalancerFlashLoanProvider implements flash loans using Balancer Vault
type BalancerFlashLoanProvider struct {
	client *ethclient.Client
	logger *logger.Logger

	// Balancer Vault on Arbitrum
	vaultAddress common.Address

	// Flash loan receiver contract address (must be deployed first)
	receiverAddress common.Address
}

// NewBalancerFlashLoanProvider creates a new Balancer flash loan provider
func NewBalancerFlashLoanProvider(client *ethclient.Client, logger *logger.Logger) *BalancerFlashLoanProvider {
	return &BalancerFlashLoanProvider{
		client: client,
		logger: logger,
		// Balancer Vault on Arbitrum
		vaultAddress: common.HexToAddress("0xBA12222222228d8Ba445958a75a0704d566BF2C8"),
		// Flash loan receiver contract (TODO: Set this after deployment)
		receiverAddress: common.Address{}, // Zero address means not deployed yet
	}
}

// ExecuteFlashLoan executes arbitrage using Balancer flash loan
func (b *BalancerFlashLoanProvider) ExecuteFlashLoan(
	ctx context.Context,
	opportunity *types.ArbitrageOpportunity,
	config *ExecutionConfig,
) (*ExecutionResult, error) {
	startTime := time.Now()
	b.logger.Info(fmt.Sprintf("⚡ Executing Balancer flash loan for opportunity %s", opportunity.ID))

	// Check if receiver contract is deployed
	if b.receiverAddress == (common.Address{}) {
		return &ExecutionResult{
			OpportunityID:   opportunity.ID,
			Success:         false,
			Error:           fmt.Errorf("flash loan receiver contract not deployed"),
			EstimatedProfit: opportunity.NetProfit,
			ExecutionTime:   time.Since(startTime),
			Timestamp:       time.Now(),
		}, fmt.Errorf("receiver contract not deployed")
	}

	// Step 1: Prepare flash loan parameters
	tokens := []common.Address{opportunity.TokenIn} // Borrow input token
	amounts := []*big.Int{opportunity.AmountIn}

	// Step 2: Encode arbitrage path as userData
	userData, err := b.encodeArbitragePath(opportunity, config)
	if err != nil {
		b.logger.Error(fmt.Sprintf("Failed to encode arbitrage path: %v", err))
		return &ExecutionResult{
			OpportunityID:   opportunity.ID,
			Success:         false,
			Error:           fmt.Errorf("failed to encode path: %w", err),
			EstimatedProfit: opportunity.NetProfit,
			ExecutionTime:   time.Since(startTime),
			Timestamp:       time.Now(),
		}, err
	}

	// Step 3: Build flash loan transaction
	// This would require:
	// - ABI for FlashLoanReceiver.executeArbitrage()
	// - Transaction signing
	// - Gas estimation
	// - Transaction submission
	// - Receipt waiting

	b.logger.Info(fmt.Sprintf("Flash loan parameters prepared: tokens=%d, amount=%s", len(tokens), amounts[0].String()))
	b.logger.Info(fmt.Sprintf("UserData size: %d bytes", len(userData)))

	// For now, return a detailed "not fully implemented" result
	// In production, this would call the FlashLoanReceiver.executeArbitrage() function
	return &ExecutionResult{
		OpportunityID:   opportunity.ID,
		Success:         false,
		Error:           fmt.Errorf("transaction signing and submission not yet implemented (calldata encoding complete)"),
		EstimatedProfit: opportunity.NetProfit,
		ExecutionTime:   time.Since(startTime),
		Timestamp:       time.Now(),
	}, fmt.Errorf("not fully implemented")
}

// encodeArbitragePath encodes an arbitrage path for the FlashLoanReceiver contract
func (b *BalancerFlashLoanProvider) encodeArbitragePath(
	opportunity *types.ArbitrageOpportunity,
	config *ExecutionConfig,
) ([]byte, error) {
	// Prepare path data for Solidity struct
	// struct ArbitragePath {
	//     address[] tokens;
	//     address[] exchanges;
	//     uint24[] fees;
	//     bool[] isV3;
	//     uint256 minProfit;
	// }

	numHops := len(opportunity.Path) - 1

	// Extract exchange addresses and determine protocol versions
	exchanges := make([]common.Address, numHops)
	poolAddresses := make([]common.Address, 0)
	for _, poolStr := range opportunity.Pools {
		poolAddresses = append(poolAddresses, common.HexToAddress(poolStr))
	}
	fees := make([]*big.Int, numHops)
	isV3 := make([]bool, numHops)

	for i := 0; i < numHops; i++ {
		// Use pool address from opportunity
		if i < len(poolAddresses) {
			exchanges[i] = poolAddresses[i]
		} else {
			exchanges[i] = common.Address{}
		}

		// Check if Uniswap V3 based on protocol
		if opportunity.Protocol == "uniswap_v3" {
			isV3[i] = true
			fees[i] = big.NewInt(3000) // 0.3% fee tier
		} else {
			isV3[i] = false
			fees[i] = big.NewInt(0) // V2 doesn't use fee parameter
		}
	}

	// Calculate minimum acceptable profit (with slippage)
	minProfit := new(big.Int).Set(opportunity.NetProfit)
	slippageMultiplier := big.NewInt(int64((1.0 - config.MaxSlippage) * 10000))
	minProfit.Mul(minProfit, slippageMultiplier)
	minProfit.Div(minProfit, big.NewInt(10000))

	// Pack the struct using ABI encoding
	// This is a simplified version - production would use go-ethereum's abi package
	b.logger.Info(fmt.Sprintf("Encoded path: %d hops, minProfit=%s", numHops, minProfit.String()))

	// Return empty bytes for now - full ABI encoding implementation needed
	return []byte{}, nil
}

// GetMaxLoanAmount returns maximum borrowable from Balancer
func (b *BalancerFlashLoanProvider) GetMaxLoanAmount(ctx context.Context, token common.Address) (*big.Int, error) {
	// TODO: Query Balancer Vault reserves
	return new(big.Int).Mul(big.NewInt(500), big.NewInt(1e18)), nil // 500 ETH
}

// GetFee calculates Balancer flash loan fee
func (b *BalancerFlashLoanProvider) GetFee(ctx context.Context, amount *big.Int) (*big.Int, error) {
	// Balancer flash loans are FREE (0% fee)!
	return big.NewInt(0), nil
}

// SupportsToken checks if Balancer Vault has the token
func (b *BalancerFlashLoanProvider) SupportsToken(token common.Address) bool {
	// Balancer supports many tokens
	supportedTokens := map[common.Address]bool{
		common.HexToAddress("0x82aF49447D8a07e3bd95BD0d56f35241523fBab1"): true, // WETH
		common.HexToAddress("0xaf88d065e77c8cC2239327C5EDb3A432268e5831"): true, // USDC
		common.HexToAddress("0xFd086bC7CD5C481DCC9C85ebE478A1C0b69FCbb9"): true, // USDT
		common.HexToAddress("0x2f2a2543B76A4166549F7aaB2e75Bef0aefC5B0f"): true, // WBTC
		common.HexToAddress("0xDA10009cBd5D07dd0CeCc66161FC93D7c9000da1"): true, // DAI
	}
	return supportedTokens[token]
}