package market

import (
	"context"
	"fmt"
	"sync"
	"time"

	"github.com/your-username/mev-beta/internal/config"
	"github.com/your-username/mev-beta/internal/logger"
	"github.com/ethereum/go-ethereum/common"
	"github.com/holiman/uint256"
	"golang.org/x/sync/singleflight"
)

// MarketManager manages market data and pool information
type MarketManager struct {
	config        *config.UniswapConfig
	logger        *logger.Logger
	pools         map[string]*PoolData
	mu            sync.RWMutex
	cacheGroup    singleflight.Group
	cacheDuration time.Duration
	maxCacheSize  int
}

// PoolData represents data for a Uniswap V3 pool
type PoolData 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
}

// NewMarketManager creates a new market manager
func NewMarketManager(cfg *config.UniswapConfig, logger *logger.Logger) *MarketManager {
	return &MarketManager{
		config:        cfg,
		logger:        logger,
		pools:         make(map[string]*PoolData),
		cacheDuration: time.Duration(cfg.Cache.Expiration) * time.Second,
		maxCacheSize:  cfg.Cache.MaxSize,
	}
}

// GetPool retrieves pool data, either from cache or by fetching it
func (mm *MarketManager) GetPool(ctx context.Context, poolAddress common.Address) (*PoolData, error) {
	// Check if we have it in cache and it's still valid
	poolKey := poolAddress.Hex()
	
	mm.mu.RLock()
	if pool, exists := mm.pools[poolKey]; exists {
		// Check if cache is still valid
		if time.Since(pool.LastUpdated) < mm.cacheDuration {
			mm.mu.RUnlock()
			return pool, nil
		}
	}
	mm.mu.RUnlock()

	// Use singleflight to prevent duplicate requests for the same pool
	result, err, _ := mm.cacheGroup.Do(poolKey, func() (interface{}, error) {
		return mm.fetchPoolData(ctx, poolAddress)
	})
	
	if err != nil {
		return nil, err
	}
	
	pool := result.(*PoolData)
	
	// Update cache
	mm.mu.Lock()
	// Check if we need to evict old entries
	if len(mm.pools) >= mm.maxCacheSize {
		mm.evictOldest()
	}
	mm.pools[poolKey] = pool
	mm.mu.Unlock()
	
	return pool, nil
}

// fetchPoolData fetches pool data from the blockchain
func (mm *MarketManager) fetchPoolData(ctx context.Context, poolAddress common.Address) (*PoolData, error) {
	// This is a simplified implementation
	// In practice, you would interact with the Ethereum blockchain to get real data
	
	// For now, we'll return mock data
	pool := &PoolData{
		Address:      poolAddress,
		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(),
	}
	
	mm.logger.Debug(fmt.Sprintf("Fetched pool data for %s", poolAddress.Hex()))
	
	return pool, nil
}

// evictOldest removes the oldest entry from the cache
func (mm *MarketManager) evictOldest() {
	oldestKey := ""
	var oldestTime time.Time
	
	for key, pool := range mm.pools {
		if oldestKey == "" || pool.LastUpdated.Before(oldestTime) {
			oldestKey = key
			oldestTime = pool.LastUpdated
		}
	}
	
	if oldestKey != "" {
		delete(mm.pools, oldestKey)
		mm.logger.Debug(fmt.Sprintf("Evicted pool %s from cache", oldestKey))
	}
}

// UpdatePool updates pool data
func (mm *MarketManager) UpdatePool(poolAddress common.Address, liquidity *uint256.Int, sqrtPriceX96 *uint256.Int, tick int) {
	poolKey := poolAddress.Hex()
	
	mm.mu.Lock()
	defer mm.mu.Unlock()
	
	if pool, exists := mm.pools[poolKey]; exists {
		pool.Liquidity = liquidity
		pool.SqrtPriceX96 = sqrtPriceX96
		pool.Tick = tick
		pool.LastUpdated = time.Now()
	} else {
		// Create new pool entry
		pool := &PoolData{
			Address:      poolAddress,
			Liquidity:    liquidity,
			SqrtPriceX96: sqrtPriceX96,
			Tick:         tick,
			LastUpdated:  time.Now(),
		}
		mm.pools[poolKey] = pool
	}
}

// GetPoolsByTokens retrieves pools for a pair of tokens
func (mm *MarketManager) GetPoolsByTokens(token0, token1 common.Address) []*PoolData {
	mm.mu.RLock()
	defer mm.mu.RUnlock()
	
	pools := make([]*PoolData, 0)
	
	for _, pool := range mm.pools {
		// Check if this pool contains the token pair
		if (pool.Token0 == token0 && pool.Token1 == token1) || 
		   (pool.Token0 == token1 && pool.Token1 == token0) {
			pools = append(pools, pool)
		}
	}
	
	return pools
}

// GetAllPools returns all cached pools
func (mm *MarketManager) GetAllPools() []*PoolData {
	mm.mu.RLock()
	defer mm.mu.RUnlock()
	
	pools := make([]*PoolData, 0, len(mm.pools))
	for _, pool := range mm.pools {
		pools = append(pools, pool)
	}
	
	return pools
}

// ClearCache clears all cached pool data
func (mm *MarketManager) ClearCache() {
	mm.mu.Lock()
	defer mm.mu.Unlock()
	
	mm.pools = make(map[string]*PoolData)
	mm.logger.Info("Cleared pool cache")
}

// GetCacheStats returns cache statistics
func (mm *MarketManager) GetCacheStats() (int, int) {
	mm.mu.RLock()
	defer mm.mu.RUnlock()
	
	return len(mm.pools), mm.maxCacheSize
}