mev-beta/pkg/parsers/example_usage.go

//go:build examples
// +build examples

package parsers

// This file demonstrates how to use the parser factory with multiple protocol parsers,
// swap logging, and Arbiscan validation for MEV bot operations.

import (
	"context"
	"fmt"
	"log/slog"
	"math/big"
	"os"

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

	"github.com/your-org/mev-bot/pkg/cache"
	"github.com/your-org/mev-bot/pkg/observability"
	mevtypes "github.com/your-org/mev-bot/pkg/types"
	"github.com/your-org/mev-bot/pkg/validation"
)

// ExampleSetup demonstrates complete parser setup with all supported protocols
func ExampleSetup() {
	ctx := context.Background()

	// 1. Create logger
	logger := observability.NewLogger(slog.LevelInfo)

	// 2. Create pool cache
	poolCache := cache.NewPoolCache()

	// 3. Populate cache with known pools (would come from pool discovery in production)
	populatePoolCache(ctx, poolCache)

	// 4. Create parser factory
	factory := NewFactory()

	// 5. Register all protocol parsers
	uniswapV2Parser := NewUniswapV2Parser(poolCache, logger)
	uniswapV3Parser := NewUniswapV3Parser(poolCache, logger)
	curveParser := NewCurveParser(poolCache, logger)

	factory.RegisterParser(mevtypes.ProtocolUniswapV2, uniswapV2Parser)
	factory.RegisterParser(mevtypes.ProtocolUniswapV3, uniswapV3Parser)
	factory.RegisterParser(mevtypes.ProtocolCurve, curveParser)

	// 6. Create swap logger for testing and validation
	swapLogger, _ := NewSwapLogger("./logs/swaps", logger)

	// 7. Create Arbiscan validator
	arbiscanAPIKey := os.Getenv("ARBISCAN_API_KEY")
	arbiscanValidator := NewArbiscanValidator(arbiscanAPIKey, logger, swapLogger)

	// 8. Create validator with rules
	validationRules := validation.DefaultValidationRules()
	validator := validation.NewValidator(validationRules)

	// Now ready to parse transactions
	fmt.Println("✅ Parser factory initialized with 3 protocols")
	fmt.Println("✅ Swap logging enabled")
	fmt.Println("✅ Arbiscan validation enabled")

	// Example usage (see ExampleParseTransaction)
	_ = factory
	_ = validator
	_ = swapLogger
	_ = arbiscanValidator
}

// ExampleParseTransaction shows how to parse a transaction with multiple swaps
func ExampleParseTransaction(
	factory *factory,
	tx *types.Transaction,
	receipt *types.Receipt,
	validator validation.Validator,
	swapLogger *SwapLogger,
) ([]*mevtypes.SwapEvent, error) {
	ctx := context.Background()

	// 1. Parse all swap events from the transaction
	events, err := factory.ParseTransaction(ctx, tx, receipt)
	if err != nil {
		return nil, fmt.Errorf("failed to parse transaction: %w", err)
	}

	// 2. Validate each event
	validEvents := validator.FilterValid(ctx, events)

	// 3. Log valid swaps for testing/analysis
	if len(validEvents) > 0 {
		swapLogger.LogSwapBatch(ctx, validEvents, "multi-protocol")
	}

	// 4. Return valid events for arbitrage detection
	return validEvents, nil
}

// ExampleArbitrageDetection shows how to detect arbitrage opportunities
func ExampleArbitrageDetection(events []*mevtypes.SwapEvent, poolCache cache.PoolCache) {
	ctx := context.Background()

	// Group events by token pairs
	type TokenPair struct {
		Token0, Token1 common.Address
	}

	eventsByPair := make(map[TokenPair][]*mevtypes.SwapEvent)

	for _, event := range events {
		pair := TokenPair{
			Token0: event.Token0,
			Token1: event.Token1,
		}
		eventsByPair[pair] = append(eventsByPair[pair], event)
	}

	// For each token pair, compare prices across protocols
	for pair, pairEvents := range eventsByPair {
		if len(pairEvents) < 2 {
			continue // Need at least 2 events to compare
		}

		// Compare V2 vs V3 prices
		for i, event1 := range pairEvents {
			for j, event2 := range pairEvents {
				if i >= j {
					continue
				}

				// Check if protocols are different
				if event1.Protocol == event2.Protocol {
					continue
				}

				// Calculate implied prices
				price1 := calculateImpliedPrice(event1)
				price2 := calculateImpliedPrice(event2)

				// Calculate price difference
				priceDiff := new(big.Float).Sub(price1, price2)
				priceDiff.Abs(priceDiff)

				// If price difference > threshold, we have an arbitrage opportunity
				threshold := big.NewFloat(0.001) // 0.1%
				if priceDiff.Cmp(threshold) > 0 {
					fmt.Printf("🎯 Arbitrage opportunity found!\n")
					fmt.Printf("  Pair: %s/%s\n", pair.Token0.Hex()[:10], pair.Token1.Hex()[:10])
					fmt.Printf("  %s price: %s\n", event1.Protocol, price1.Text('f', 6))
					fmt.Printf("  %s price: %s\n", event2.Protocol, price2.Text('f', 6))
					fmt.Printf("  Difference: %s\n", priceDiff.Text('f', 6))

					// Calculate potential profit
					profit := simulateArbitrage(ctx, event1, event2, poolCache)
					if profit.Sign() > 0 {
						fmt.Printf("  💰 Estimated profit: %s ETH\n", profit.Text('f', 6))
					}
				}
			}
		}
	}
}

// ExampleMultiHopArbitrage shows how to detect multi-hop arbitrage (A→B→C→A)
func ExampleMultiHopArbitrage(poolCache cache.PoolCache) {
	ctx := context.Background()

	// Example: WETH → USDC → DAI → WETH arbitrage on Uniswap V3

	// Pool 1: WETH/USDC
	poolWETH_USDC, _ := poolCache.GetByAddress(ctx, common.HexToAddress("0x1111"))

	// Pool 2: USDC/DAI
	poolUSDC_DAI, _ := poolCache.GetByAddress(ctx, common.HexToAddress("0x2222"))

	// Pool 3: DAI/WETH
	poolDAI_WETH, _ := poolCache.GetByAddress(ctx, common.HexToAddress("0x3333"))

	// Simulate route: 1 WETH → USDC → DAI → WETH
	startAmount := big.NewInt(1000000000000000000) // 1 WETH

	// Step 1: WETH → USDC
	usdcAmount, priceAfter1, _ := CalculateSwapAmounts(
		poolWETH_USDC.SqrtPriceX96,
		poolWETH_USDC.Liquidity,
		startAmount,
		true, // WETH = token0
		3000, // 0.3% fee
	)

	// Step 2: USDC → DAI
	daiAmount, priceAfter2, _ := CalculateSwapAmounts(
		poolUSDC_DAI.SqrtPriceX96,
		poolUSDC_DAI.Liquidity,
		usdcAmount,
		true, // USDC = token0
		500, // 0.05% fee (Curve-like)
	)

	// Step 3: DAI → WETH
	finalWETH, priceAfter3, _ := CalculateSwapAmounts(
		poolDAI_WETH.SqrtPriceX96,
		poolDAI_WETH.Liquidity,
		daiAmount,
		false, // WETH = token1
		3000,  // 0.3% fee
	)

	// Calculate profit
	profit := new(big.Int).Sub(finalWETH, startAmount)

	if profit.Sign() > 0 {
		fmt.Printf("🚀 Multi-hop arbitrage opportunity!\n")
		fmt.Printf("  Route: WETH → USDC → DAI → WETH\n")
		fmt.Printf("  Input: %s WETH\n", formatAmount(startAmount, 18))
		fmt.Printf("  Output: %s WETH\n", formatAmount(finalWETH, 18))
		fmt.Printf("  💰 Profit: %s WETH\n", formatAmount(profit, 18))
		fmt.Printf("  Prices: %v → %v → %v\n", priceAfter1, priceAfter2, priceAfter3)
	} else {
		fmt.Printf("❌ No profit: %s WETH loss\n", formatAmount(new(big.Int).Abs(profit), 18))
	}
}

// Helper functions

func populatePoolCache(ctx context.Context, poolCache cache.PoolCache) {
	// Example pools (would come from discovery service in production)

	// Uniswap V2: WETH/USDC
	poolCache.Add(ctx, &mevtypes.PoolInfo{
		Address:        common.HexToAddress("0xC31E54c7a869B9FcBEcc14363CF510d1c41fa443"),
		Protocol:       mevtypes.ProtocolUniswapV2,
		Token0:         common.HexToAddress("0x82aF49447D8a07e3bd95BD0d56f35241523fBab1"), // WETH
		Token1:         common.HexToAddress("0xFF970A61A04b1cA14834A43f5dE4533eBDDB5CC8"), // USDC
		Token0Decimals: 18,
		Token1Decimals: 6,
		Fee:            30, // 0.3%
		IsActive:       true,
	})

	// Uniswap V3: WETH/USDC 0.05%
	poolCache.Add(ctx, &mevtypes.PoolInfo{
		Address:        common.HexToAddress("0xC31E54c7a869B9FcBEcc14363CF510d1c41fa444"),
		Protocol:       mevtypes.ProtocolUniswapV3,
		Token0:         common.HexToAddress("0x82aF49447D8a07e3bd95BD0d56f35241523fBab1"), // WETH
		Token1:         common.HexToAddress("0xFF970A61A04b1cA14834A43f5dE4533eBDDB5CC8"), // USDC
		Token0Decimals: 18,
		Token1Decimals: 6,
		Fee:            500, // 0.05%
		SqrtPriceX96:   new(big.Int).Lsh(big.NewInt(1), 96),
		Liquidity:      big.NewInt(1000000000000),
		IsActive:       true,
	})

	// Curve: USDC/USDT
	poolCache.Add(ctx, &mevtypes.PoolInfo{
		Address:        common.HexToAddress("0x7f90122BF0700F9E7e1F688fe926940E8839F353"),
		Protocol:       mevtypes.ProtocolCurve,
		Token0:         common.HexToAddress("0xFF970A61A04b1cA14834A43f5dE4533eBDDB5CC8"), // USDC
		Token1:         common.HexToAddress("0xFd086bC7CD5C481DCC9C85ebE478A1C0b69FCbb9"), // USDT
		Token0Decimals: 6,
		Token1Decimals: 6,
		Fee:            4, // 0.04%
		AmpCoefficient: big.NewInt(2000),
		IsActive:       true,
	})
}

func calculateImpliedPrice(event *mevtypes.SwapEvent) *big.Float {
	// Calculate price as amountOut / amountIn
	var amountIn, amountOut *big.Int

	if event.Amount0In.Sign() > 0 {
		amountIn = event.Amount0In
		amountOut = event.Amount1Out
	} else {
		amountIn = event.Amount1In
		amountOut = event.Amount0Out
	}

	if amountIn.Sign() == 0 {
		return big.NewFloat(0)
	}

	amountInFloat := new(big.Float).SetInt(amountIn)
	amountOutFloat := new(big.Float).SetInt(amountOut)

	price := new(big.Float).Quo(amountOutFloat, amountInFloat)
	return price
}

func simulateArbitrage(
	ctx context.Context,
	event1, event2 *mevtypes.SwapEvent,
	poolCache cache.PoolCache,
) *big.Float {
	// Simplified arbitrage simulation
	// In production, this would:
	// 1. Calculate optimal trade size
	// 2. Account for gas costs
	// 3. Account for slippage
	// 4. Check liquidity constraints

	// For now, return mock profit
	return big.NewFloat(0.05) // 0.05 ETH profit
}

func formatAmount(amount *big.Int, decimals uint8) string {
	// Convert to float and format
	amountFloat := new(big.Float).SetInt(amount)
	divisor := new(big.Float).SetInt(new(big.Int).Exp(big.NewInt(10), big.NewInt(int64(decimals)), nil))
	result := new(big.Float).Quo(amountFloat, divisor)
	return result.Text('f', 6)
}

// ExampleRealTimeMonitoring shows how to monitor pending transactions
func ExampleRealTimeMonitoring() {
	fmt.Println("📡 Real-time MEV bot monitoring pattern:")
	fmt.Println("")
	fmt.Println("1. Subscribe to pending transactions (mempool)")
	fmt.Println("2. Parse swaps using factory.ParseTransaction()")
	fmt.Println("3. Validate using validator.FilterValid()")
	fmt.Println("4. Detect arbitrage across protocols")
	fmt.Println("5. Calculate profitability (profit - gas)")
	fmt.Println("6. Execute if profitable (front-run, sandwich, or arbitrage)")
	fmt.Println("7. Log results with swapLogger for analysis")
	fmt.Println("8. Validate accuracy with arbiscanValidator")
	fmt.Println("")
	fmt.Println("Performance targets:")
	fmt.Println("  - Parse: < 5ms")
	fmt.Println("  - Validate: < 2ms")
	fmt.Println("  - Detect: < 10ms")
	fmt.Println("  - Execute: < 30ms")
	fmt.Println("  - Total: < 50ms end-to-end")
}