// Package contracts provides integration with MEV smart contracts for arbitrage execution
package contracts

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

	"github.com/ethereum/go-ethereum/accounts/abi/bind"
	"github.com/ethereum/go-ethereum/common"
	etypes "github.com/ethereum/go-ethereum/core/types"
	"github.com/ethereum/go-ethereum/ethclient"

	"github.com/fraktal/mev-beta/bindings/contracts"
	"github.com/fraktal/mev-beta/bindings/flashswap"
	"github.com/fraktal/mev-beta/internal/config"
	"github.com/fraktal/mev-beta/internal/logger"
	"github.com/fraktal/mev-beta/pkg/security"
	stypes "github.com/fraktal/mev-beta/pkg/types"
)

// ContractExecutor handles execution of arbitrage opportunities through smart contracts
type ContractExecutor struct {
	config          *config.BotConfig
	logger          *logger.Logger
	client          *ethclient.Client
	keyManager      *security.KeyManager
	arbitrage       *contracts.ArbitrageExecutor
	flashSwapper    *flashswap.BaseFlashSwapper
	privateKey      string
	accountAddress  common.Address
	chainID         *big.Int
	gasPrice        *big.Int
	pendingNonce    uint64
	lastNonceUpdate time.Time
}

// NewContractExecutor creates a new contract executor
func NewContractExecutor(
	cfg *config.Config,
	logger *logger.Logger,
	keyManager *security.KeyManager,
) (*ContractExecutor, error) {
	// Connect to Ethereum client
	client, err := ethclient.Dial(cfg.Arbitrum.RPCEndpoint)
	if err != nil {
		return nil, fmt.Errorf("failed to connect to Ethereum node: %w", err)
	}

	// Parse contract addresses from config
	arbitrageAddr := common.HexToAddress(cfg.Contracts.ArbitrageExecutor)
	flashSwapperAddr := common.HexToAddress(cfg.Contracts.FlashSwapper)

	// Create contract instances
	arbitrageContract, err := contracts.NewArbitrageExecutor(arbitrageAddr, client)
	if err != nil {
		return nil, fmt.Errorf("failed to instantiate arbitrage contract: %w", err)
	}

	flashSwapperContract, err := flashswap.NewBaseFlashSwapper(flashSwapperAddr, client)
	if err != nil {
		return nil, fmt.Errorf("failed to instantiate flash swapper contract: %w", err)
	}

	// Get chain ID
	chainID, err := client.ChainID(context.Background())
	if err != nil {
		return nil, fmt.Errorf("failed to get chain ID: %w", err)
	}

	executor := &ContractExecutor{
		config:         &cfg.Bot,
		logger:         logger,
		client:         client,
		keyManager:     keyManager,
		arbitrage:      arbitrageContract,
		flashSwapper:   flashSwapperContract,
		privateKey:     "",               // Will be retrieved from keyManager when needed
		accountAddress: common.Address{}, // Will be retrieved from keyManager when needed
		chainID:        chainID,
		gasPrice:       big.NewInt(0),
		pendingNonce:   0,
	}

	// Initialize gas price
	if err := executor.updateGasPrice(); err != nil {
		logger.Warn(fmt.Sprintf("Failed to initialize gas price: %v", err))
	}

	logger.Info("Contract executor initialized successfully")
	return executor, nil
}

// ExecuteArbitrage executes a standard arbitrage opportunity
func (ce *ContractExecutor) ExecuteArbitrage(ctx context.Context, opportunity stypes.ArbitrageOpportunity) (*etypes.Transaction, error) {
	ce.logger.Info(fmt.Sprintf("Executing arbitrage opportunity: %+v", opportunity))

	// Convert opportunity to contract parameters
	params := ce.convertToArbitrageParams(opportunity)

	// Prepare transaction options
	opts, err := ce.prepareTransactionOpts(ctx)
	if err != nil {
		return nil, fmt.Errorf("failed to prepare transaction options: %w", err)
	}

	// Execute arbitrage through contract - convert interface types using correct field names
	arbitrageParams := contracts.IArbitrageArbitrageParams{
		Tokens:    params.Tokens,
		Pools:     params.Pools,
		Amounts:   params.Amounts,
		SwapData:  params.SwapData,
		MinProfit: params.MinProfit,
	}
	tx, err := ce.arbitrage.ExecuteArbitrage(opts, arbitrageParams)
	if err != nil {
		return nil, fmt.Errorf("failed to execute arbitrage: %w", err)
	}

	ce.logger.Info(fmt.Sprintf("Arbitrage transaction submitted: %s", tx.Hash().Hex()))
	return tx, nil
}

// ExecuteTriangularArbitrage executes a triangular arbitrage opportunity
func (ce *ContractExecutor) ExecuteTriangularArbitrage(ctx context.Context, opportunity stypes.ArbitrageOpportunity) (*etypes.Transaction, error) {
	ce.logger.Info(fmt.Sprintf("Executing triangular arbitrage opportunity: %+v", opportunity))

	// Convert opportunity to contract parameters
	params := ce.convertToTriangularArbitrageParams(opportunity)

	// Prepare transaction options
	opts, err := ce.prepareTransactionOpts(ctx)
	if err != nil {
		return nil, fmt.Errorf("failed to prepare transaction options: %w", err)
	}

	// Execute triangular arbitrage through contract - convert interface types
	triangularParams := contracts.IArbitrageTriangularArbitrageParams{
		TokenA:     params.TokenA,
		TokenB:     params.TokenB,
		TokenC:     params.TokenC,
		PoolAB:     params.PoolAB,
		PoolBC:     params.PoolBC,
		PoolCA:     params.PoolCA,
		AmountIn:   params.AmountIn,
		MinProfit:  params.MinProfit,
		SwapDataAB: params.SwapDataAB,
		SwapDataBC: params.SwapDataBC,
		SwapDataCA: params.SwapDataCA,
	}
	tx, err := ce.arbitrage.ExecuteTriangularArbitrage(opts, triangularParams)
	if err != nil {
		return nil, fmt.Errorf("failed to execute triangular arbitrage: %w", err)
	}

	ce.logger.Info(fmt.Sprintf("Triangular arbitrage transaction submitted: %s", tx.Hash().Hex()))
	return tx, nil
}

// convertToArbitrageParams converts a scanner opportunity to contract parameters
func (ce *ContractExecutor) convertToArbitrageParams(opportunity stypes.ArbitrageOpportunity) contracts.IArbitrageArbitrageParams {
	// Convert token addresses
	tokens := make([]common.Address, len(opportunity.Path))
	for i, token := range opportunity.Path {
		tokens[i] = common.HexToAddress(token)
	}

	// Convert pool addresses
	pools := make([]common.Address, len(opportunity.Pools))
	for i, pool := range opportunity.Pools {
		pools[i] = common.HexToAddress(pool)
	}

	// Convert amounts (simplified for now)
	amounts := make([]*big.Int, len(pools))
	for i := range amounts {
		// Use a default amount for now - in practice this should be calculated based on optimal trade size
		amounts[i] = big.NewInt(1000000000000000000) // 1 ETH equivalent
	}

	// Convert swap data (empty for now - in practice this would contain encoded swap parameters)
	swapData := make([][]byte, len(pools))
	for i := range swapData {
		swapData[i] = []byte{}
	}

	// Create parameters struct
	params := contracts.IArbitrageArbitrageParams{
		Tokens:    tokens,
		Pools:     pools,
		Amounts:   amounts,
		SwapData:  swapData,
		MinProfit: opportunity.Profit, // Use estimated profit as minimum required profit
	}

	return params
}

// convertToTriangularArbitrageParams converts a scanner opportunity to triangular arbitrage parameters
func (ce *ContractExecutor) convertToTriangularArbitrageParams(opportunity stypes.ArbitrageOpportunity) contracts.IArbitrageTriangularArbitrageParams {
	// For triangular arbitrage, we expect exactly 3 tokens forming a triangle
	if len(opportunity.Path) < 3 {
		ce.logger.Error("Invalid triangular arbitrage path - insufficient tokens")
		return contracts.IArbitrageTriangularArbitrageParams{}
	}

	// Extract the three tokens
	tokenA := common.HexToAddress(opportunity.Path[0])
	tokenB := common.HexToAddress(opportunity.Path[1])
	tokenC := common.HexToAddress(opportunity.Path[2])

	// Extract pools (should be 3 for triangular arbitrage)
	if len(opportunity.Pools) < 3 {
		ce.logger.Error("Invalid triangular arbitrage pools - insufficient pools")
		return contracts.IArbitrageTriangularArbitrageParams{}
	}

	poolAB := common.HexToAddress(opportunity.Pools[0])
	poolBC := common.HexToAddress(opportunity.Pools[1])
	poolCA := common.HexToAddress(opportunity.Pools[2])

	// Create parameters struct
	// Calculate optimal input amount based on opportunity size
	amountIn := opportunity.AmountIn
	if amountIn == nil || amountIn.Sign() == 0 {
		// Use 10% of estimated profit as input amount for triangular arbitrage
		amountIn = new(big.Int).Div(opportunity.Profit, big.NewInt(10))
		if amountIn.Cmp(big.NewInt(1000000000000000)) < 0 { // Minimum 0.001 ETH
			amountIn = big.NewInt(1000000000000000)
		}
	}

	// Generate swap data for each leg of the triangular arbitrage
	swapDataAB, err := ce.generateSwapData(tokenA, tokenB, poolAB)
	if err != nil {
		ce.logger.Warn(fmt.Sprintf("Failed to generate swap data AB: %v", err))
		swapDataAB = []byte{} // Fallback to empty data
	}

	swapDataBC, err := ce.generateSwapData(tokenB, tokenC, poolBC)
	if err != nil {
		ce.logger.Warn(fmt.Sprintf("Failed to generate swap data BC: %v", err))
		swapDataBC = []byte{} // Fallback to empty data
	}

	swapDataCA, err := ce.generateSwapData(tokenC, tokenA, poolCA)
	if err != nil {
		ce.logger.Warn(fmt.Sprintf("Failed to generate swap data CA: %v", err))
		swapDataCA = []byte{} // Fallback to empty data
	}

	params := contracts.IArbitrageTriangularArbitrageParams{
		TokenA:     tokenA,
		TokenB:     tokenB,
		TokenC:     tokenC,
		PoolAB:     poolAB,
		PoolBC:     poolBC,
		PoolCA:     poolCA,
		AmountIn:   amountIn,
		MinProfit:  opportunity.Profit,
		SwapDataAB: swapDataAB,
		SwapDataBC: swapDataBC,
		SwapDataCA: swapDataCA,
	}

	return params
}

// generateSwapData generates the appropriate swap data based on the pool type
func (ce *ContractExecutor) generateSwapData(tokenIn, tokenOut, pool common.Address) ([]byte, error) {
	// Check if this is a Uniswap V3 pool by trying to call the fee function
	if fee, err := ce.getUniswapV3Fee(pool); err == nil {
		// This is a Uniswap V3 pool - generate V3 swap data
		return ce.generateUniswapV3SwapData(tokenIn, tokenOut, fee)
	}

	// Check if this is a Uniswap V2 pool by trying to call getReserves
	if err := ce.checkUniswapV2Pool(pool); err == nil {
		// This is a Uniswap V2 pool - generate V2 swap data
		return ce.generateUniswapV2SwapData(tokenIn, tokenOut)
	}

	// Unknown pool type - return empty data
	return []byte{}, nil
}

// generateUniswapV3SwapData generates swap data for Uniswap V3 pools
func (ce *ContractExecutor) generateUniswapV3SwapData(tokenIn, tokenOut common.Address, fee uint32) ([]byte, error) {
	// Encode the recipient and deadline for the swap
	// This is a simplified implementation - production would include more parameters
	_ = struct {
		TokenIn           common.Address
		TokenOut          common.Address
		Fee               uint32
		Recipient         common.Address
		Deadline          *big.Int
		AmountOutMinimum  *big.Int
		SqrtPriceLimitX96 *big.Int
	}{
		TokenIn:           tokenIn,
		TokenOut:          tokenOut,
		Fee:               fee,
		Recipient:         common.Address{}, // Will be set by contract
		Deadline:          big.NewInt(time.Now().Add(10 * time.Minute).Unix()),
		AmountOutMinimum:  big.NewInt(1), // Accept any amount for now
		SqrtPriceLimitX96: big.NewInt(0), // No price limit
	}

	// In production, this would use proper ABI encoding
	// For now, return a simple encoding
	return []byte(fmt.Sprintf("v3:%s:%s:%d", tokenIn.Hex(), tokenOut.Hex(), fee)), nil
}

// generateUniswapV2SwapData generates swap data for Uniswap V2 pools
func (ce *ContractExecutor) generateUniswapV2SwapData(tokenIn, tokenOut common.Address) ([]byte, error) {
	// V2 swaps are simpler - just need token addresses and path
	_ = struct {
		TokenIn  common.Address
		TokenOut common.Address
		To       common.Address
		Deadline *big.Int
	}{
		TokenIn:  tokenIn,
		TokenOut: tokenOut,
		To:       common.Address{}, // Will be set by contract
		Deadline: big.NewInt(time.Now().Add(10 * time.Minute).Unix()),
	}

	// Simple encoding for V2 swaps
	return []byte(fmt.Sprintf("v2:%s:%s", tokenIn.Hex(), tokenOut.Hex())), nil
}

// getUniswapV3Fee tries to get the fee from a Uniswap V3 pool
func (ce *ContractExecutor) getUniswapV3Fee(pool common.Address) (uint32, error) {
	// In production, this would call the fee() function on the pool contract
	// For now, return a default fee
	return 3000, nil // 0.3% fee
}

// checkUniswapV2Pool checks if an address is a Uniswap V2 pool
func (ce *ContractExecutor) checkUniswapV2Pool(pool common.Address) error {
	// In production, this would call getReserves() to verify it's a V2 pool
	// For now, just return success
	return nil
}

// prepareTransactionOpts prepares transaction options with proper gas pricing and nonce
func (ce *ContractExecutor) prepareTransactionOpts(ctx context.Context) (*bind.TransactOpts, error) {
	// Update gas price if needed
	if err := ce.updateGasPrice(); err != nil {
		ce.logger.Warn(fmt.Sprintf("Failed to update gas price: %v", err))
	}

	// Get current nonce
	nonce, err := ce.client.PendingNonceAt(ctx, ce.accountAddress)
	if err != nil {
		return nil, fmt.Errorf("failed to get account nonce: %w", err)
	}

	// Check nonce safely before creating transaction options
	nonceInt64, err := security.SafeUint64ToInt64(nonce)
	if err != nil {
		ce.logger.Error("Nonce exceeds int64 maximum", "nonce", nonce, "error", err)
		return nil, fmt.Errorf("nonce value exceeds maximum: %w", err)
	}

	// Create transaction options
	opts := &bind.TransactOpts{
		From:     ce.accountAddress,
		Nonce:    big.NewInt(nonceInt64),
		Signer:   ce.signTransaction, // Custom signer function
		Value:    big.NewInt(0),      // No ETH value for arbitrage transactions
		GasPrice: ce.gasPrice,
		GasLimit: 0, // Let the node estimate gas limit
		Context:  ctx,
		NoSend:   false,
	}

	return opts, nil
}

// updateGasPrice updates the gas price estimate
func (ce *ContractExecutor) updateGasPrice() error {
	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
	defer cancel()

	// Get suggested gas price from node
	gasPrice, err := ce.client.SuggestGasPrice(ctx)
	if err != nil {
		return fmt.Errorf("failed to suggest gas price: %w", err)
	}

	// Use the suggested gas price directly (no multiplier from config)
	ce.gasPrice = gasPrice

	return nil
}

// signTransaction signs a transaction with the configured private key
func (ce *ContractExecutor) signTransaction(address common.Address, tx *etypes.Transaction) (*etypes.Transaction, error) {
	// Get the private key from the key manager
	privateKey, err := ce.keyManager.GetActivePrivateKey()
	if err != nil {
		return nil, fmt.Errorf("failed to get private key: %w", err)
	}

	// Get the chain ID for proper signing
	chainID, err := ce.client.NetworkID(context.Background())
	if err != nil {
		return nil, fmt.Errorf("failed to get chain ID: %w", err)
	}

	ce.logger.Debug(fmt.Sprintf("Signing transaction with chain ID %s", chainID.String()))

	// Create EIP-155 signer for the current chain
	signer := etypes.NewEIP155Signer(chainID)

	// Sign the transaction
	signedTx, err := etypes.SignTx(tx, signer, privateKey)
	if err != nil {
		return nil, fmt.Errorf("failed to sign transaction: %w", err)
	}

	ce.logger.Debug(fmt.Sprintf("Transaction signed successfully: %s", signedTx.Hash().Hex()))
	return signedTx, nil
}

// GetClient returns the ethereum client for external use
func (ce *ContractExecutor) GetClient() *ethclient.Client {
	return ce.client
}

// Close closes the contract executor and releases resources
func (ce *ContractExecutor) Close() {
	if ce.client != nil {
		ce.client.Close()
	}
}