package scanner

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

	"github.com/fraktal/mev-beta/internal/config"
	"github.com/fraktal/mev-beta/internal/logger"
	"github.com/fraktal/mev-beta/pkg/events"
	"github.com/fraktal/mev-beta/pkg/uniswap"
	"github.com/ethereum/go-ethereum/common"
	"github.com/holiman/uint256"
	"golang.org/x/sync/singleflight"
)

// MarketScanner scans markets for price movement opportunities with concurrency
type MarketScanner struct {
	config     *config.BotConfig
	logger     *logger.Logger
	workerPool chan chan EventDetails
	workers    []*EventWorker
	wg         sync.WaitGroup
	cacheGroup singleflight.Group
	cache      map[string]*CachedData
	cacheMutex sync.RWMutex
	cacheTTL   time.Duration
}

// EventWorker represents a worker that processes event details
type EventWorker struct {
	ID         int
	WorkerPool chan chan EventDetails
	JobChannel chan EventDetails
	QuitChan   chan bool
	scanner    *MarketScanner
}

// NewMarketScanner creates a new market scanner with concurrency support
func NewMarketScanner(cfg *config.BotConfig, logger *logger.Logger) *MarketScanner {
	scanner := &MarketScanner{
		config:     cfg,
		logger:     logger,
		workerPool: make(chan chan EventDetails, cfg.MaxWorkers),
		workers:    make([]*EventWorker, 0, cfg.MaxWorkers),
		cache:      make(map[string]*CachedData),
		cacheTTL:   time.Duration(cfg.RPCTimeout) * time.Second,
	}

	// Create workers
	for i := 0; i < cfg.MaxWorkers; i++ {
		worker := NewEventWorker(i, scanner.workerPool, scanner)
		scanner.workers = append(scanner.workers, worker)
		worker.Start()
	}

	// Start cache cleanup routine
	go scanner.cleanupCache()

	return scanner
}

// NewEventWorker creates a new event worker
func NewEventWorker(id int, workerPool chan chan EventDetails, scanner *MarketScanner) *EventWorker {
	return &EventWorker{
		ID:         id,
		WorkerPool: workerPool,
		JobChannel: make(chan EventDetails),
		QuitChan:   make(chan bool),
		scanner:    scanner,
	}
}

// Start begins the worker
func (w *EventWorker) Start() {
	go func() {
		for {
			// Register the worker in the worker pool
			w.WorkerPool <- w.JobChannel

			select {
			case job := <-w.JobChannel:
				// Process the job
				w.Process(job)
			case <-w.QuitChan:
				// Stop the worker
				return
			}
		}
	}()
}

// Stop terminates the worker
func (w *EventWorker) Stop() {
	go func() {
		w.QuitChan <- true
	}()
}

// Process handles an event detail
func (w *EventWorker) Process(event EventDetails) {
	// Analyze the event in a separate goroutine to maintain throughput
	go func() {
		defer w.scanner.wg.Done()

		// Log the processing
		w.scanner.logger.Debug(fmt.Sprintf("Worker %d processing %s event in pool %s from protocol %s", 
			w.ID, event.Type.String(), event.PoolAddress, event.Protocol))

		// Analyze based on event type
		switch event.Type {
		case events.Swap:
			w.scanner.analyzeSwapEvent(event)
		case events.AddLiquidity:
			w.scanner.analyzeLiquidityEvent(event, true)
		case events.RemoveLiquidity:
			w.scanner.analyzeLiquidityEvent(event, false)
		case events.NewPool:
			w.scanner.analyzeNewPoolEvent(event)
		default:
			w.scanner.logger.Debug(fmt.Sprintf("Worker %d received unknown event type: %d", w.ID, event.Type))
		}
	}()
}

// SubmitEvent submits an event for processing by the worker pool
func (s *MarketScanner) SubmitEvent(event EventDetails) {
	s.wg.Add(1)

	// Get an available worker job channel
	jobChannel := <-s.workerPool

	// Send the job to the worker
	jobChannel <- event
}

// analyzeSwapEvent analyzes a swap event for arbitrage opportunities
func (s *MarketScanner) analyzeSwapEvent(event EventDetails) {
	s.logger.Debug(fmt.Sprintf("Analyzing swap event in pool %s", event.PoolAddress))

	// Get pool data with caching
	poolData, err := s.getPoolData(event.PoolAddress)
	if err != nil {
		s.logger.Error(fmt.Sprintf("Error getting pool data for %s: %v", event.PoolAddress, err))
		return
	}

	// Calculate price impact
	priceMovement, err := s.calculatePriceMovement(event, poolData)
	if err != nil {
		s.logger.Error(fmt.Sprintf("Error calculating price movement for pool %s: %v", event.PoolAddress, err))
		return
	}

	// Check if the movement is significant
	if s.isSignificantMovement(priceMovement, s.config.MinProfitThreshold) {
		s.logger.Info(fmt.Sprintf("Significant price movement detected in pool %s: %+v", event.PoolAddress, priceMovement))
		
		// Look for arbitrage opportunities
		opportunities := s.findArbitrageOpportunities(event, priceMovement)
		if len(opportunities) > 0 {
			s.logger.Info(fmt.Sprintf("Found %d arbitrage opportunities for pool %s", len(opportunities), event.PoolAddress))
			for _, opp := range opportunities {
				s.logger.Info(fmt.Sprintf("Arbitrage opportunity: %+v", opp))
			}
		}
	} else {
		s.logger.Debug(fmt.Sprintf("Price movement in pool %s is not significant: %f", event.PoolAddress, priceMovement.PriceImpact))
	}
}

// analyzeLiquidityEvent analyzes liquidity events (add/remove)
func (s *MarketScanner) analyzeLiquidityEvent(event EventDetails, isAdd bool) {
	action := "adding"
	if !isAdd {
		action = "removing"
	}
	s.logger.Debug(fmt.Sprintf("Analyzing liquidity event (%s) in pool %s", action, event.PoolAddress))

	// Update cached pool data
	s.updatePoolData(event)

	s.logger.Info(fmt.Sprintf("Liquidity %s event processed for pool %s", action, event.PoolAddress))
}

// analyzeNewPoolEvent analyzes new pool creation events
func (s *MarketScanner) analyzeNewPoolEvent(event EventDetails) {
	s.logger.Info(fmt.Sprintf("New pool created: %s (protocol: %s)", event.PoolAddress, event.Protocol))

	// Add to known pools
	// In a real implementation, you would want to fetch and cache the pool data
	s.logger.Debug(fmt.Sprintf("Added new pool %s to monitoring", event.PoolAddress))
}

// calculatePriceMovement calculates the price movement from a swap event
func (s *MarketScanner) calculatePriceMovement(event EventDetails, poolData *CachedData) (*PriceMovement, error) {
	// Calculate the price before the swap
	priceBefore := uniswap.SqrtPriceX96ToPrice(poolData.SqrtPriceX96.ToBig())

	priceMovement := &PriceMovement{
		Token0:      event.Token0,
		Token1:      event.Token1,
		Pool:        event.PoolAddress,
		Protocol:    event.Protocol,
		AmountIn:    new(big.Int).Add(event.Amount0In, event.Amount1In),
		AmountOut:   new(big.Int).Add(event.Amount0Out, event.Amount1Out),
		PriceBefore: priceBefore,
		TickBefore:  event.Tick,
		Timestamp:   event.Timestamp,
	}

	// Calculate price impact (simplified)
	// In practice, this would involve more complex calculations using Uniswap V3 math
	if priceMovement.AmountIn.Cmp(big.NewInt(0)) > 0 {
		impact := new(big.Float).Quo(
			new(big.Float).SetInt(priceMovement.AmountOut),
			new(big.Float).SetInt(priceMovement.AmountIn),
		)
		priceImpact, _ := impact.Float64()
		priceMovement.PriceImpact = priceImpact
	}

	return priceMovement, nil
}

// isSignificantMovement determines if a price movement is significant enough to exploit
func (s *MarketScanner) isSignificantMovement(movement *PriceMovement, threshold float64) bool {
	// Check if the price impact is above our threshold
	return movement.PriceImpact > threshold
}

// findArbitrageOpportunities looks for arbitrage opportunities based on price movements
func (s *MarketScanner) findArbitrageOpportunities(event EventDetails, movement *PriceMovement) []ArbitrageOpportunity {
	s.logger.Debug(fmt.Sprintf("Searching for arbitrage opportunities for pool %s", event.PoolAddress))

	opportunities := make([]ArbitrageOpportunity, 0)

	// This would contain logic to:
	// 1. Compare prices across different pools for the same token pair
	// 2. Calculate potential profit after gas costs
	// 3. Identify triangular arbitrage opportunities
	// 4. Check if the opportunity is profitable

	// For now, we'll return a mock opportunity for demonstration
	opp := ArbitrageOpportunity{
		Path:        []string{event.Token0, event.Token1},
		Pools:       []string{event.PoolAddress, "0xMockPoolAddress"},
		Profit:      big.NewInt(1000000000000000000), // 1 ETH
		GasEstimate: big.NewInt(200000000000000000),  // 0.2 ETH
		ROI:         5.0, // 500%
		Protocol:    event.Protocol,
	}
	opportunities = append(opportunities, opp)

	return opportunities
}

// Stop stops the market scanner and all workers
func (s *MarketScanner) Stop() {
	// Stop all workers
	for _, worker := range s.workers {
		worker.Stop()
	}

	// Wait for all jobs to complete
	s.wg.Wait()
}

// ArbitrageOpportunity represents a potential arbitrage opportunity
type ArbitrageOpportunity struct {
	Path        []string // Token path for the arbitrage
	Pools       []string // Pools involved in the arbitrage
	Profit      *big.Int // Estimated profit in wei
	GasEstimate *big.Int // Estimated gas cost
	ROI         float64  // Return on investment percentage
	Protocol    string   // DEX protocol
}

// PriceMovement represents a potential price movement
type PriceMovement struct {
	Token0      string     // Token address
	Token1      string     // Token address
	Pool        string     // Pool address
	Protocol    string     // DEX protocol
	AmountIn    *big.Int   // Amount of token being swapped in
	AmountOut   *big.Int   // Amount of token being swapped out
	PriceBefore *big.Float // Price before the swap
	PriceAfter  *big.Float // Price after the swap (to be calculated)
	PriceImpact float64    // Calculated price impact
	TickBefore  int        // Tick before the swap
	TickAfter   int        // Tick after the swap (to be calculated)
	Timestamp   time.Time  // Event timestamp
}

// EventDetails contains details about a detected event
type EventDetails struct {
	Type           events.EventType
	Protocol       string
	PoolAddress    string
	Token0         string
	Token1         string
	Amount0In      *big.Int
	Amount0Out     *big.Int
	Amount1In      *big.Int
	Amount1Out     *big.Int
	SqrtPriceX96   *uint256.Int
	Liquidity      *uint256.Int
	Tick           int
	Timestamp      time.Time
	TransactionHash common.Hash
}

// CachedData represents cached pool data
type CachedData struct {
	Address       common.Address
	Token0        common.Address
	Token1        common.Address
	Fee           int64
	Liquidity     *uint256.Int
	SqrtPriceX96  *uint256.Int
	Tick          int
	TickSpacing   int
	LastUpdated   time.Time
}

// getPoolData retrieves pool data with caching
func (s *MarketScanner) getPoolData(poolAddress string) (*CachedData, error) {
	// Check cache first
	cacheKey := fmt.Sprintf("pool_%s", poolAddress)
	
	s.cacheMutex.RLock()
	if data, exists := s.cache[cacheKey]; exists && time.Since(data.LastUpdated) < s.cacheTTL {
		s.cacheMutex.RUnlock()
		s.logger.Debug(fmt.Sprintf("Cache hit for pool %s", poolAddress))
		return data, nil
	}
	s.cacheMutex.RUnlock()

	// Use singleflight to prevent duplicate requests
	result, err, _ := s.cacheGroup.Do(cacheKey, func() (interface{}, error) {
		return s.fetchPoolData(poolAddress)
	})

	if err != nil {
		return nil, err
	}

	poolData := result.(*CachedData)

	// Update cache
	s.cacheMutex.Lock()
	s.cache[cacheKey] = poolData
	s.cacheMutex.Unlock()

	s.logger.Debug(fmt.Sprintf("Fetched and cached pool data for %s", poolAddress))
	return poolData, nil
}

// fetchPoolData fetches pool data from the blockchain
func (s *MarketScanner) fetchPoolData(poolAddress string) (*CachedData, error) {
	s.logger.Debug(fmt.Sprintf("Fetching pool data for %s", poolAddress))

	// This is a simplified implementation
	// In practice, you would interact with the Ethereum blockchain to get real data
	address := common.HexToAddress(poolAddress)

	// For now, we'll return mock data
	pool := &CachedData{
		Address:      address,
		Token0:       common.HexToAddress("0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48"), // USDC
		Token1:       common.HexToAddress("0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2"), // WETH
		Fee:          3000, // 0.3%
		Liquidity:    uint256.NewInt(1000000000000000000), // 1 ETH equivalent
		SqrtPriceX96: uint256.NewInt(2505414483750470000), // Mock sqrt price
		Tick:         200000, // Mock tick
		TickSpacing:  60,    // Tick spacing for 0.3% fee
		LastUpdated:  time.Now(),
	}

	s.logger.Debug(fmt.Sprintf("Fetched pool data for %s", poolAddress))
	return pool, nil
}

// updatePoolData updates cached pool data
func (s *MarketScanner) updatePoolData(event EventDetails) {
	cacheKey := fmt.Sprintf("pool_%s", event.PoolAddress)

	s.cacheMutex.Lock()
	defer s.cacheMutex.Unlock()

	// Update existing cache entry or create new one
	data := &CachedData{
		Address:      common.HexToAddress(event.PoolAddress),
		Token0:       common.HexToAddress(event.Token0),
		Token1:       common.HexToAddress(event.Token1),
		Liquidity:    event.Liquidity,
		SqrtPriceX96: event.SqrtPriceX96,
		Tick:         event.Tick,
		LastUpdated:  time.Now(),
	}

	s.cache[cacheKey] = data
	s.logger.Debug(fmt.Sprintf("Updated cache for pool %s", event.PoolAddress))
}

// cleanupCache removes expired cache entries
func (s *MarketScanner) cleanupCache() {
	ticker := time.NewTicker(10 * time.Minute)
	defer ticker.Stop()

	for {
		select {
		case <-ticker.C:
			s.cacheMutex.Lock()
			for key, data := range s.cache {
				if time.Since(data.LastUpdated) > s.cacheTTL {
					delete(s.cache, key)
					s.logger.Debug(fmt.Sprintf("Removed expired cache entry: %s", key))
				}
			}
			s.cacheMutex.Unlock()
		}
	}
}