package risk

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

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

// RiskManager manages risk for MEV operations
type RiskManager struct {
	logger           *logger.Logger
	mu               sync.RWMutex
	decimalConverter *math.DecimalConverter

	// Position limits
	maxPositionSize           *big.Int // Maximum position size in wei
	dailyLossLimit            *big.Int // Maximum daily loss in wei
	maxConcurrent             int      // Maximum concurrent positions
	maxPositionSizeDecimal    *math.UniversalDecimal
	dailyLossLimitDecimal     *math.UniversalDecimal
	minProfitThresholdDecimal *math.UniversalDecimal
	maxGasPriceDecimal        *math.UniversalDecimal

	// Current state
	currentPositions int
	dailyLoss        *big.Int
	lastReset        time.Time

	// Risk metrics
	totalTrades        uint64
	successfulTrades   uint64
	failedTrades       uint64
	totalProfit        *big.Int
	totalLoss          *big.Int
	totalProfitDecimal *math.UniversalDecimal
	totalLossDecimal   *math.UniversalDecimal

	// Configuration
	minProfitThreshold *big.Int // Minimum profit threshold in wei
	maxSlippage        float64  // Maximum acceptable slippage
	maxGasPrice        *big.Int // Maximum gas price willing to pay

	// Circuit breaker
	circuitBreaker *CircuitBreaker
}

func (rm *RiskManager) fromWei(value *big.Int, symbol string) *math.UniversalDecimal {
	if value == nil {
		zero, _ := math.NewUniversalDecimal(big.NewInt(0), 18, symbol)
		return zero
	}
	decimals := uint8(18)
	if symbol == "GWEI" {
		decimals = 9
	}
	return rm.decimalConverter.FromWei(value, decimals, symbol)
}

// RiskAssessment represents a risk assessment for an MEV opportunity
type RiskAssessment struct {
	OpportunityID          string
	RiskScore              float64  // 0-1, higher = riskier
	Confidence             float64  // 0-1, higher = more confident
	MaxPositionSize        *big.Int // Maximum position size for this opportunity
	RecommendedGas         *big.Int // Recommended gas price
	SlippageLimit          float64  // Maximum slippage for this opportunity
	Profitability          float64  // Expected ROI percentage
	Acceptable             bool     // Whether the opportunity passes risk checks
	Reason                 string   // Reason for acceptance/rejection
	MaxPositionSizeDecimal *math.UniversalDecimal
	RecommendedGasDecimal  *math.UniversalDecimal
}

// CircuitBreaker manages circuit breaking for risk control
type CircuitBreaker struct {
	failures         int
	lastFailure      time.Time
	resetTimeout     time.Duration
	failureThreshold int
	open             bool
	mu               sync.RWMutex
}

// NewRiskManager creates a new risk manager
func NewRiskManager(logger *logger.Logger) *RiskManager {
	dc := math.NewDecimalConverter()

	rm := &RiskManager{
		logger:             logger,
		decimalConverter:   dc,
		maxPositionSize:    big.NewInt(1000000000000000000), // 1 ETH
		dailyLossLimit:     big.NewInt(100000000000000000),  // 0.1 ETH
		maxConcurrent:      5,
		currentPositions:   0,
		dailyLoss:          big.NewInt(0),
		lastReset:          time.Now(),
		totalTrades:        0,
		successfulTrades:   0,
		failedTrades:       0,
		totalProfit:        big.NewInt(0),
		totalLoss:          big.NewInt(0),
		minProfitThreshold: big.NewInt(10000000000000000), // 0.01 ETH
		maxSlippage:        0.01,                          // 1%
		maxGasPrice:        big.NewInt(20000000000),       // 20 gwei
		circuitBreaker: &CircuitBreaker{
			resetTimeout:     5 * time.Minute,
			failureThreshold: 3,
		},
	}

	rm.maxPositionSizeDecimal, _ = math.NewUniversalDecimal(new(big.Int).Set(rm.maxPositionSize), 18, "ETH")
	rm.dailyLossLimitDecimal, _ = math.NewUniversalDecimal(new(big.Int).Set(rm.dailyLossLimit), 18, "ETH")
	rm.minProfitThresholdDecimal, _ = math.NewUniversalDecimal(new(big.Int).Set(rm.minProfitThreshold), 18, "ETH")
	rm.maxGasPriceDecimal, _ = math.NewUniversalDecimal(new(big.Int).Set(rm.maxGasPrice), 9, "GWEI")
	rm.totalProfitDecimal, _ = math.NewUniversalDecimal(big.NewInt(0), 18, "ETH")
	rm.totalLossDecimal, _ = math.NewUniversalDecimal(big.NewInt(0), 18, "ETH")

	// Start daily reset timer
	go rm.dailyReset()

	return rm
}

// AssessOpportunity assesses the risk of an MEV opportunity
func (rm *RiskManager) AssessOpportunity(opportunityID string, expectedProfit, gasCost *big.Int, slippage float64, gasPrice *big.Int) *RiskAssessment {
	rm.mu.Lock()
	defer rm.mu.Unlock()

	assessment := &RiskAssessment{
		OpportunityID:          opportunityID,
		RiskScore:              0.0,
		Confidence:             0.0,
		MaxPositionSize:        big.NewInt(0),
		RecommendedGas:         big.NewInt(0),
		SlippageLimit:          0.0,
		Profitability:          0.0,
		Acceptable:             false,
		Reason:                 "",
		MaxPositionSizeDecimal: rm.maxPositionSizeDecimal,
		RecommendedGasDecimal:  rm.maxGasPriceDecimal,
	}

	// Check circuit breaker
	if rm.circuitBreaker.IsOpen() {
		assessment.Reason = "Circuit breaker is open"
		return assessment
	}

	expectedProfitDec := rm.fromWei(expectedProfit, "ETH")
	gasPriceDec := rm.fromWei(gasPrice, "GWEI")
	dailyLossDec := rm.fromWei(rm.dailyLoss, "ETH")

	// Check if we've exceeded concurrent position limits
	if rm.currentPositions >= rm.maxConcurrent {
		assessment.Reason = fmt.Sprintf("Maximum concurrent positions reached: %d", rm.maxConcurrent)
		return assessment
	}

	// Check if we've exceeded daily loss limits
	if cmp, err := rm.decimalConverter.Compare(dailyLossDec, rm.dailyLossLimitDecimal); err == nil && cmp > 0 {
		assessment.Reason = fmt.Sprintf("Daily loss limit exceeded: %s > %s",
			rm.decimalConverter.ToHumanReadable(dailyLossDec),
			rm.decimalConverter.ToHumanReadable(rm.dailyLossLimitDecimal))
		return assessment
	}

	// Check minimum profit threshold
	if cmp, err := rm.decimalConverter.Compare(expectedProfitDec, rm.minProfitThresholdDecimal); err == nil && cmp < 0 {
		assessment.Reason = fmt.Sprintf("Profit below minimum threshold: %s < %s",
			rm.decimalConverter.ToHumanReadable(expectedProfitDec),
			rm.decimalConverter.ToHumanReadable(rm.minProfitThresholdDecimal))
		return assessment
	}

	// Check slippage tolerance
	if slippage > rm.maxSlippage {
		assessment.Reason = fmt.Sprintf("Slippage exceeds limit: %.2f%% > %.2f%%",
			slippage*100, rm.maxSlippage*100)
		return assessment
	}

	// Check gas price limits
	if cmp, err := rm.decimalConverter.Compare(gasPriceDec, rm.maxGasPriceDecimal); err == nil && cmp > 0 {
		assessment.Reason = fmt.Sprintf("Gas price exceeds limit: %s > %s",
			rm.decimalConverter.ToHumanReadable(gasPriceDec),
			rm.decimalConverter.ToHumanReadable(rm.maxGasPriceDecimal))
		return assessment
	}

	// Calculate risk score based on multiple factors
	riskScore := rm.calculateRiskScore(expectedProfit, gasCost, slippage, gasPrice)
	assessment.RiskScore = riskScore

	// Calculate confidence based on historical performance
	confidence := rm.calculateConfidence()
	assessment.Confidence = confidence

	// Calculate profitability (ROI percentage)
	profitability := rm.calculateProfitability(expectedProfit, gasCost)
	assessment.Profitability = profitability

	// Determine maximum position size based on risk
	maxPosition := rm.calculateMaxPositionSize(riskScore, expectedProfit, gasCost)
	assessment.MaxPositionSize = maxPosition
	assessment.MaxPositionSizeDecimal = rm.fromWei(maxPosition, "ETH")

	// Recommend gas price based on network conditions and risk
	recommendedGas := rm.calculateRecommendedGas(gasPrice, riskScore)
	assessment.RecommendedGas = recommendedGas
	assessment.RecommendedGasDecimal = rm.fromWei(recommendedGas, "GWEI")

	// Set slippage limit based on risk tolerance
	slippageLimit := rm.calculateSlippageLimit(riskScore)
	assessment.SlippageLimit = slippageLimit

	// Determine if opportunity is acceptable
	acceptable := rm.isAcceptable(riskScore, profitability, confidence)
	assessment.Acceptable = acceptable

	if acceptable {
		assessment.Reason = "Opportunity passes all risk checks"
	} else {
		assessment.Reason = fmt.Sprintf("Risk score too high: %.2f", riskScore)
	}

	rm.logger.Debug(fmt.Sprintf("Risk assessment for %s: Risk=%.2f, Confidence=%.2f, Profitability=%.2f%%, Acceptable=%t",
		opportunityID, riskScore, confidence, profitability, acceptable))

	return assessment
}

// RecordTrade records the result of a trade for risk management
func (rm *RiskManager) RecordTrade(success bool, profit, gasCost *big.Int) {
	rm.mu.Lock()
	defer rm.mu.Unlock()

	rm.totalTrades++
	if success {
		rm.successfulTrades++
		if profit != nil {
			rm.totalProfit.Add(rm.totalProfit, profit)
			profitDec := rm.fromWei(profit, "ETH")
			rm.totalProfitDecimal, _ = rm.decimalConverter.Add(rm.totalProfitDecimal, profitDec)
		}
	} else {
		rm.failedTrades++
		if gasCost != nil {
			rm.totalLoss.Add(rm.totalLoss, gasCost)
			rm.dailyLoss.Add(rm.dailyLoss, gasCost)
			lossDec := rm.fromWei(gasCost, "ETH")
			rm.totalLossDecimal, _ = rm.decimalConverter.Add(rm.totalLossDecimal, lossDec)
		}
	}

	// Update circuit breaker
	if !success {
		rm.circuitBreaker.RecordFailure()
	} else {
		rm.circuitBreaker.RecordSuccess()
	}

	rm.logger.Debug(fmt.Sprintf("Trade recorded: Success=%t, Profit=%s, Gas=%s, DailyLoss=%s",
		success,
		rm.decimalConverter.ToHumanReadable(rm.fromWei(profit, "ETH")),
		rm.decimalConverter.ToHumanReadable(rm.fromWei(gasCost, "ETH")),
		rm.decimalConverter.ToHumanReadable(rm.fromWei(rm.dailyLoss, "ETH"))))
}

// UpdatePositionCount updates the current position count
func (rm *RiskManager) UpdatePositionCount(delta int) {
	rm.mu.Lock()
	defer rm.mu.Unlock()

	rm.currentPositions += delta
	if rm.currentPositions < 0 {
		rm.currentPositions = 0
	}

	rm.logger.Debug(fmt.Sprintf("Position count updated: %d", rm.currentPositions))
}

// GetStatistics returns risk management statistics
func (rm *RiskManager) GetStatistics() map[string]interface{} {
	rm.mu.RLock()
	defer rm.mu.RUnlock()

	return map[string]interface{}{
		"total_trades":         rm.totalTrades,
		"successful_trades":    rm.successfulTrades,
		"failed_trades":        rm.failedTrades,
		"success_rate":         float64(rm.successfulTrades) / float64(max(1, rm.totalTrades)),
		"total_profit":         rm.decimalConverter.ToHumanReadable(rm.totalProfitDecimal),
		"total_loss":           rm.decimalConverter.ToHumanReadable(rm.totalLossDecimal),
		"daily_loss":           rm.decimalConverter.ToHumanReadable(rm.fromWei(rm.dailyLoss, "ETH")),
		"daily_loss_limit":     rm.decimalConverter.ToHumanReadable(rm.dailyLossLimitDecimal),
		"current_positions":    rm.currentPositions,
		"max_concurrent":       rm.maxConcurrent,
		"circuit_breaker_open": rm.circuitBreaker.IsOpen(),
		"min_profit_threshold": rm.decimalConverter.ToHumanReadable(rm.minProfitThresholdDecimal),
		"max_slippage":         rm.maxSlippage * 100, // Convert to percentage
		"max_gas_price":        rm.decimalConverter.ToHumanReadable(rm.maxGasPriceDecimal),
	}
}

// dailyReset resets daily counters
func (rm *RiskManager) dailyReset() {
	ticker := time.NewTicker(24 * time.Hour)
	defer ticker.Stop()

	for {
		<-ticker.C
		rm.mu.Lock()
		rm.dailyLoss = big.NewInt(0)
		rm.lastReset = time.Now()
		rm.mu.Unlock()
		rm.logger.Info("Daily risk counters reset")
	}
}

// calculateRiskScore calculates a risk score based on multiple factors
func (rm *RiskManager) calculateRiskScore(expectedProfit, gasCost *big.Int, slippage float64, gasPrice *big.Int) float64 {
	// Base risk (0-0.3)
	baseRisk := 0.1

	// Gas risk (0-0.3) - higher gas = higher risk
	gasRisk := 0.0
	if gasPrice != nil && rm.maxGasPrice != nil && rm.maxGasPrice.Sign() > 0 {
		gasRatio := new(big.Float).Quo(new(big.Float).SetInt(gasPrice), new(big.Float).SetInt(rm.maxGasPrice))
		gasRatioFloat, _ := gasRatio.Float64()
		gasRisk = gasRatioFloat * 0.3
		if gasRisk > 0.3 {
			gasRisk = 0.3
		}
	}

	// Slippage risk (0-0.2) - higher slippage = higher risk
	slippageRisk := slippage * 0.2
	if slippageRisk > 0.2 {
		slippageRisk = 0.2
	}

	// Profit risk (0-0.2) - lower profit = higher relative risk
	profitRisk := 0.0
	if expectedProfit != nil && expectedProfit.Sign() > 0 {
		// Lower profits are riskier relative to gas costs
		if gasCost != nil && gasCost.Sign() > 0 {
			profitRatio := new(big.Float).Quo(new(big.Float).SetInt(gasCost), new(big.Float).SetInt(expectedProfit))
			profitRatioFloat, _ := profitRatio.Float64()
			profitRisk = profitRatioFloat * 0.2
			if profitRisk > 0.2 {
				profitRisk = 0.2
			}
		}
	}

	totalRisk := baseRisk + gasRisk + slippageRisk + profitRisk
	if totalRisk > 1.0 {
		totalRisk = 1.0
	}

	return totalRisk
}

// calculateConfidence calculates confidence based on historical performance
func (rm *RiskManager) calculateConfidence() float64 {
	if rm.totalTrades == 0 {
		return 0.5 // Default confidence for new system
	}

	successRate := float64(rm.successfulTrades) / float64(rm.totalTrades)
	confidence := successRate * 0.8 // Weight success rate at 80%

	// Add bonus for high volume of trades
	volumeBonus := float64(min(rm.totalTrades, 1000)) / 1000.0 * 0.2 // Max 20% bonus
	confidence += volumeBonus

	if confidence > 1.0 {
		confidence = 1.0
	}

	return confidence
}

// calculateProfitability calculates profitability as ROI percentage
func (rm *RiskManager) calculateProfitability(expectedProfit, gasCost *big.Int) float64 {
	if expectedProfit == nil || expectedProfit.Sign() <= 0 {
		return 0.0
	}

	netProfit := new(big.Int).Sub(expectedProfit, gasCost)
	if netProfit.Sign() <= 0 {
		return 0.0
	}

	// For profitability calculation, we need an investment amount
	// Use a reasonable default investment (e.g., 1 ETH)
	investment := big.NewInt(1000000000000000000) // 1 ETH

	roi := new(big.Float).Quo(new(big.Float).SetInt(netProfit), new(big.Float).SetInt(investment))
	roi.Mul(roi, big.NewFloat(100))

	roiFloat, _ := roi.Float64()
	return roiFloat
}

// calculateMaxPositionSize calculates maximum position size based on risk
func (rm *RiskManager) calculateMaxPositionSize(riskScore float64, expectedProfit, gasCost *big.Int) *big.Int {
	// Start with maximum position size
	maxPosition := new(big.Int).Set(rm.maxPositionSize)

	// Reduce position size based on risk score
	riskMultiplier := 1.0 - riskScore
	maxPositionFloat := new(big.Float).SetInt(maxPosition)
	maxPositionFloat.Mul(maxPositionFloat, big.NewFloat(riskMultiplier))

	result := new(big.Int)
	maxPositionFloat.Int(result)
	return result
}

// calculateRecommendedGas calculates recommended gas price based on risk
func (rm *RiskManager) calculateRecommendedGas(gasPrice *big.Int, riskScore float64) *big.Int {
	if gasPrice == nil {
		return big.NewInt(0)
	}

	// For high-risk opportunities, recommend higher gas price for faster execution
	// For low-risk opportunities, can use lower gas price
	gasMultiplier := 1.0 + (riskScore * 0.5) // Up to 50% increase for high risk

	recommendedGas := new(big.Float).SetInt(gasPrice)
	recommendedGas.Mul(recommendedGas, big.NewFloat(gasMultiplier))

	result := new(big.Int)
	recommendedGas.Int(result)
	return result
}

// calculateSlippageLimit calculates slippage limit based on risk
func (rm *RiskManager) calculateSlippageLimit(riskScore float64) float64 {
	// For high-risk opportunities, allow less slippage
	// For low-risk opportunities, can tolerate more slippage
	slippageLimit := rm.maxSlippage * (1.0 - riskScore*0.5) // Reduce by up to 50% for high risk
	return slippageLimit
}

// isAcceptable determines if an opportunity is acceptable based on risk criteria
func (rm *RiskManager) isAcceptable(riskScore, profitability, confidence float64) bool {
	// Must pass all individual criteria AND overall risk threshold
	if riskScore > 0.7 {
		return false // Too risky regardless of other factors
	}

	if profitability < 1.0 {
		return false // Less than 1% ROI
	}

	if confidence < 0.3 {
		return false // Low confidence
	}

	// Overall weighted score
	weightedScore := (riskScore * 0.4) + ((100 - profitability) * 0.3) + ((1 - confidence) * 0.3)
	return weightedScore < 0.5
}

// max returns the larger of two integers
func max(a, b uint64) uint64 {
	if a > b {
		return a
	}
	return b
}

// min returns the smaller of two integers
func min(a, b uint64) uint64 {
	if a < b {
		return a
	}
	return b
}

// formatEther formats a big.Int wei amount as ETH string
func formatEther(wei *big.Int) string {
	if wei == nil {
		return "0"
	}

	ether := new(big.Float).Quo(new(big.Float).SetInt(wei), big.NewFloat(1e18))
	result, _ := ether.Float64()
	return fmt.Sprintf("%.6f", result)
}

// formatGwei formats a big.Int wei amount as Gwei string
func formatGwei(wei *big.Int) string {
	if wei == nil {
		return "0"
	}

	gwei := new(big.Float).Quo(new(big.Float).SetInt(wei), big.NewFloat(1e9))
	result, _ := gwei.Float64()
	return fmt.Sprintf("%.2f", result)
}

// IsOpen checks if the circuit breaker is open
func (cb *CircuitBreaker) IsOpen() bool {
	cb.mu.RLock()
	defer cb.mu.RUnlock()
	return cb.open
}

// RecordFailure records a failure in the circuit breaker
func (cb *CircuitBreaker) RecordFailure() {
	cb.mu.Lock()
	defer cb.mu.Unlock()

	cb.failures++
	cb.lastFailure = time.Now()

	if cb.failures >= cb.failureThreshold {
		cb.open = true
	}
}

// RecordSuccess records a success in the circuit breaker and potentially closes it
func (cb *CircuitBreaker) RecordSuccess() {
	cb.mu.Lock()
	defer cb.mu.Unlock()

	// Reset failures if enough time has passed
	if time.Since(cb.lastFailure) > cb.resetTimeout {
		cb.failures = 0
		cb.open = false
	}
}