package monitor

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

	"github.com/fraktal/mev-beta/internal/config"
	"github.com/fraktal/mev-beta/internal/logger"
	"github.com/fraktal/mev-beta/internal/ratelimit"
	"github.com/fraktal/mev-beta/pkg/market"
	"github.com/fraktal/mev-beta/pkg/scanner"
	"github.com/ethereum/go-ethereum/common"
	"github.com/ethereum/go-ethereum/core/types"
	"github.com/ethereum/go-ethereum/ethclient"
	"golang.org/x/time/rate"
)

// ArbitrumMonitor monitors the Arbitrum sequencer for transactions with concurrency support
type ArbitrumMonitor struct {
	config       *config.ArbitrumConfig
	botConfig    *config.BotConfig
	client       *ethclient.Client
	logger       *logger.Logger
	rateLimiter  *ratelimit.LimiterManager
	marketMgr    *market.MarketManager
	scanner      *scanner.MarketScanner
	pipeline     *market.Pipeline
	fanManager   *market.FanManager
	limiter      *rate.Limiter
	pollInterval time.Duration
	running      bool
	mu           sync.RWMutex
}

// NewArbitrumMonitor creates a new Arbitrum monitor with rate limiting
func NewArbitrumMonitor(
	arbCfg *config.ArbitrumConfig,
	botCfg *config.BotConfig,
	logger *logger.Logger,
	rateLimiter *ratelimit.LimiterManager,
	marketMgr *market.MarketManager,
	scanner *scanner.MarketScanner,
) (*ArbitrumMonitor, error) {
	// Create Ethereum client
	client, err := ethclient.Dial(arbCfg.RPCEndpoint)
	if err != nil {
		return nil, fmt.Errorf("failed to connect to Arbitrum node: %v", err)
	}

	// Create rate limiter based on config
	limiter := rate.NewLimiter(
		rate.Limit(arbCfg.RateLimit.RequestsPerSecond),
		arbCfg.RateLimit.Burst,
	)

	// Create pipeline
	pipeline := market.NewPipeline(botCfg, logger, marketMgr, scanner)
	
	// Add default stages
	pipeline.AddDefaultStages()

	// Create fan manager
	fanManager := market.NewFanManager(
		&config.Config{
			Arbitrum: *arbCfg,
			Bot:      *botCfg,
		},
		logger,
		rateLimiter,
	)

	return &ArbitrumMonitor{
		config:       arbCfg,
		botConfig:    botCfg,
		client:       client,
		logger:       logger,
		rateLimiter:  rateLimiter,
		marketMgr:    marketMgr,
		scanner:      scanner,
		pipeline:     pipeline,
		fanManager:   fanManager,
		limiter:      limiter,
		pollInterval: time.Duration(botCfg.PollingInterval) * time.Second,
		running:      false,
	}, nil
}

// Start begins monitoring the Arbitrum sequencer
func (m *ArbitrumMonitor) Start(ctx context.Context) error {
	m.mu.Lock()
	m.running = true
	m.mu.Unlock()

	m.logger.Info("Starting Arbitrum sequencer monitoring...")

	// Get the latest block to start from
	if err := m.rateLimiter.WaitForLimit(ctx, m.config.RPCEndpoint); err != nil {
		return fmt.Errorf("rate limit error: %v", err)
	}

	header, err := m.client.HeaderByNumber(ctx, nil)
	if err != nil {
		return fmt.Errorf("failed to get latest block header: %v", err)
	}

	lastBlock := header.Number.Uint64()
	m.logger.Info(fmt.Sprintf("Starting from block: %d", lastBlock))

	for {
		m.mu.RLock()
		running := m.running
		m.mu.RUnlock()

		if !running {
			break
		}

		select {
		case <-ctx.Done():
			m.Stop()
			return nil
		case <-time.After(m.pollInterval):
			// Get the latest block
			if err := m.rateLimiter.WaitForLimit(ctx, m.config.RPCEndpoint); err != nil {
				m.logger.Error(fmt.Sprintf("Rate limit error: %v", err))
				continue
			}

			header, err := m.client.HeaderByNumber(ctx, nil)
			if err != nil {
				m.logger.Error(fmt.Sprintf("Failed to get latest block header: %v", err))
				continue
			}

			currentBlock := header.Number.Uint64()

			// Process blocks from lastBlock+1 to currentBlock
			for blockNum := lastBlock + 1; blockNum <= currentBlock; blockNum++ {
				if err := m.processBlock(ctx, blockNum); err != nil {
					m.logger.Error(fmt.Sprintf("Failed to process block %d: %v", blockNum, err))
				}
			}

			lastBlock = currentBlock
		}
	}

	return nil
}

// Stop stops the monitor
func (m *ArbitrumMonitor) Stop() {
	m.mu.Lock()
	defer m.mu.Unlock()
	m.running = false
	m.logger.Info("Stopping Arbitrum monitor...")
}

// processBlock processes a single block for potential swap transactions
func (m *ArbitrumMonitor) processBlock(ctx context.Context, blockNumber uint64) error {
	m.logger.Debug(fmt.Sprintf("Processing block %d", blockNumber))

	// Wait for rate limiter
	if err := m.rateLimiter.WaitForLimit(ctx, m.config.RPCEndpoint); err != nil {
		return fmt.Errorf("rate limit error: %v", err)
	}

	// Get block by number
	block, err := m.client.BlockByNumber(ctx, big.NewInt(int64(blockNumber)))
	if err != nil {
		return fmt.Errorf("failed to get block %d: %v", blockNumber, err)
	}

	// Process transactions through the pipeline
	transactions := block.Transactions()
	
	// Process transactions through the pipeline with block number and timestamp
	if err := m.pipeline.ProcessTransactions(ctx, transactions, blockNumber, block.Time()); err != nil {
		m.logger.Error(fmt.Sprintf("Pipeline processing error: %v", err))
	}

	return nil
}

// processTransaction analyzes a transaction for potential swap opportunities
func (m *ArbitrumMonitor) processTransaction(ctx context.Context, tx *types.Transaction) error {
	// Check if this is a potential swap transaction
	// This is a simplified check - in practice, you would check for
	// specific function signatures of Uniswap-like contracts

	// For now, we'll just log all transactions
	from, err := m.client.TransactionSender(ctx, tx, common.Hash{}, 0)
	if err != nil {
		// This can happen for pending transactions
		from = common.HexToAddress("0x0")
	}

	m.logger.Debug(fmt.Sprintf("Transaction: %s, From: %s, To: %s, Value: %s ETH",
		tx.Hash().Hex(),
		from.Hex(),
		func() string {
			if tx.To() != nil {
				return tx.To().Hex()
			}
			return "contract creation"
		}(),
		new(big.Float).Quo(new(big.Float).SetInt(tx.Value()), big.NewFloat(1e18)).String(),
	))

	// TODO: Add logic to detect swap transactions and analyze them
	// This would involve:
	// 1. Checking if the transaction is calling a Uniswap-like contract
	// 2. Decoding the swap function call
	// 3. Extracting the token addresses and amounts
	// 4. Calculating potential price impact

	return nil
}

// GetPendingTransactions retrieves pending transactions from the mempool
func (m *ArbitrumMonitor) GetPendingTransactions(ctx context.Context) ([]*types.Transaction, error) {
	// This is a simplified implementation
	// In practice, you might need to use a different approach to access pending transactions

	// Query for pending transactions
	txs := make([]*types.Transaction, 0)

	// Note: ethclient doesn't directly expose pending transactions
	// You might need to use a different approach or a custom RPC call

	return txs, nil
}