package exchanges

import (
	"fmt"
	"math/big"

	"github.com/ethereum/go-ethereum/common"
	"github.com/ethereum/go-ethereum/ethclient"

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

// CurvePoolDetector implements PoolDetector for Curve
type CurvePoolDetector struct {
	client *ethclient.Client
	logger *logger.Logger
	config *ExchangeConfig
}

// NewCurvePoolDetector creates a new Curve pool detector
func NewCurvePoolDetector(client *ethclient.Client, logger *logger.Logger, config *ExchangeConfig) *CurvePoolDetector {
	return &CurvePoolDetector{
		client: client,
		logger: logger,
		config: config,
	}
}

// GetAllPools returns all pools containing the specified tokens
func (d *CurvePoolDetector) GetAllPools(token0, token1 common.Address) ([]common.Address, error) {
	// In a real implementation, this would query the registry contract
	// For now, we'll return an empty slice
	return []common.Address{}, nil
}

// GetPoolForPair returns the pool address for a specific token pair
func (d *CurvePoolDetector) GetPoolForPair(token0, token1 common.Address) (common.Address, error) {
	// In a real implementation, this would query the registry for pools
	// containing both tokens
	poolAddress := common.HexToAddress("0x0") // Placeholder

	// For now, return empty address to indicate pool not found
	return poolAddress, nil
}

// GetSupportedFeeTiers returns supported fee tiers for Curve (varies by pool)
func (d *CurvePoolDetector) GetSupportedFeeTiers() []int64 {
	// Curve pools can have different fee tiers
	return []int64{400, 1000, 4000} // 0.04%, 0.1%, 0.4% in basis points
}

// GetPoolType returns the pool type
func (d *CurvePoolDetector) GetPoolType() string {
	return "curve_stable_swap"
}

// CurveLiquidityFetcher implements LiquidityFetcher for Curve
type CurveLiquidityFetcher struct {
	client *ethclient.Client
	logger *logger.Logger
	config *ExchangeConfig
	engine *math.ExchangePricingEngine
}

// NewCurveLiquidityFetcher creates a new Curve liquidity fetcher
func NewCurveLiquidityFetcher(client *ethclient.Client, logger *logger.Logger, config *ExchangeConfig, engine *math.ExchangePricingEngine) *CurveLiquidityFetcher {
	return &CurveLiquidityFetcher{
		client: client,
		logger: logger,
		config: config,
		engine: engine,
	}
}

// GetPoolData fetches pool information for Curve
func (f *CurveLiquidityFetcher) GetPoolData(poolAddress common.Address) (*math.PoolData, error) {
	// In a real implementation, this would call the pool contract to get reserves and other data
	// For now, return a placeholder pool data with Curve-specific fields

	fee, err := math.NewUniversalDecimal(big.NewInt(400), 4, "FEE")
	if err != nil {
		return nil, fmt.Errorf("error creating fee decimal: %w", err)
	}

	reserve0, err := math.NewUniversalDecimal(big.NewInt(1000000000000), 6, "RESERVE0") // USDC has 6 decimals
	if err != nil {
		return nil, fmt.Errorf("error creating reserve0 decimal: %w", err)
	}

	reserve1, err := math.NewUniversalDecimal(big.NewInt(1000000000000), 6, "RESERVE1") // USDT has 6 decimals
	if err != nil {
		return nil, fmt.Errorf("error creating reserve1 decimal: %w", err)
	}

	return &math.PoolData{
		Address:      poolAddress.Hex(),
		ExchangeType: math.ExchangeCurve,
		Fee:          fee,
		Token0:       math.TokenInfo{Address: "0x0", Symbol: "USDC", Decimals: 6},
		Token1:       math.TokenInfo{Address: "0x1", Symbol: "USDT", Decimals: 6},
		Reserve0:     reserve0,
		Reserve1:     reserve1,
		A:            big.NewInt(2000), // Amplification coefficient for stable swaps
	}, nil
}

// GetTokenReserves fetches reserves for a specific token pair in a pool
func (f *CurveLiquidityFetcher) GetTokenReserves(poolAddress, token0, token1 common.Address) (*big.Int, *big.Int, error) {
	// In a real implementation, this would query the pool contract
	// For now, return placeholder values
	return big.NewInt(1000000000000), big.NewInt(1000000000000), nil
}

// GetPoolPrice calculates the price of token1 in terms of token0
func (f *CurveLiquidityFetcher) GetPoolPrice(poolAddress common.Address) (*big.Float, error) {
	poolData, err := f.GetPoolData(poolAddress)
	if err != nil {
		return nil, err
	}

	pricer, err := f.engine.GetExchangePricer(poolData.ExchangeType)
	if err != nil {
		return nil, err
	}

	spotPrice, err := pricer.GetSpotPrice(poolData)
	if err != nil {
		return nil, err
	}

	// Convert the UniversalDecimal Value to a *big.Float
	result := new(big.Float).SetInt(spotPrice.Value)
	return result, nil
}

// GetLiquidityDepth calculates the liquidity depth for an amount
func (f *CurveLiquidityFetcher) GetLiquidityDepth(poolAddress, tokenIn common.Address, amount *big.Int) (*big.Int, error) {
	// In a real implementation, this would calculate liquidity with Curve's stable swap formula
	return amount, nil
}

// CurveSwapRouter implements SwapRouter for Curve
type CurveSwapRouter struct {
	client *ethclient.Client
	logger *logger.Logger
	config *ExchangeConfig
	engine *math.ExchangePricingEngine
}

// NewCurveSwapRouter creates a new Curve swap router
func NewCurveSwapRouter(client *ethclient.Client, logger *logger.Logger, config *ExchangeConfig, engine *math.ExchangePricingEngine) *CurveSwapRouter {
	return &CurveSwapRouter{
		client: client,
		logger: logger,
		config: config,
		engine: engine,
	}
}

// CalculateSwap calculates the expected output amount for a swap
func (r *CurveSwapRouter) CalculateSwap(tokenIn, tokenOut common.Address, amountIn *big.Int) (*big.Int, error) {
	// Find pool for the token pair
	poolAddress, err := r.findPoolForPair(tokenIn, tokenOut)
	if err != nil {
		return nil, fmt.Errorf("failed to find pool for pair: %w", err)
	}

	// Get pool data
	poolData, err := r.GetPoolData(poolAddress)
	if err != nil {
		return nil, fmt.Errorf("failed to get pool data: %w", err)
	}

	// Create a UniversalDecimal from the amountIn
	decimalAmountIn, err := math.NewUniversalDecimal(amountIn, 18, "AMOUNT_IN")
	if err != nil {
		return nil, fmt.Errorf("error creating amount in decimal: %w", err)
	}

	// Get the pricer
	pricer, err := r.engine.GetExchangePricer(poolData.ExchangeType)
	if err != nil {
		return nil, err
	}

	// Calculate amount out using Curve's stable swap formula
	amountOut, err := pricer.CalculateAmountOut(decimalAmountIn, poolData)
	if err != nil {
		return nil, err
	}

	return amountOut.Value, nil
}

// findPoolForPair finds the pool address for a given token pair
func (r *CurveSwapRouter) findPoolForPair(token0, token1 common.Address) (common.Address, error) {
	// In a real implementation, this would query the Curve registry contract
	// For now, return a placeholder address
	return common.HexToAddress("0x0"), nil
}

// GetPoolData is a helper to fetch pool data (for internal use)
func (r *CurveSwapRouter) GetPoolData(poolAddress common.Address) (*math.PoolData, error) {
	fetcher := NewCurveLiquidityFetcher(r.client, r.logger, r.config, r.engine)
	return fetcher.GetPoolData(poolAddress)
}

// GenerateSwapData generates the calldata for a swap transaction
func (r *CurveSwapRouter) GenerateSwapData(tokenIn, tokenOut common.Address, amountIn, minAmountOut *big.Int, deadline *big.Int) ([]byte, error) {
	// In a real implementation, this would generate the encoded function call
	// For Curve, this would typically be exchange or exchange_underlying
	return []byte{}, nil
}

// GetSwapRoute returns the route for a swap (for Curve, typically direct within a pool)
func (r *CurveSwapRouter) GetSwapRoute(tokenIn, tokenOut common.Address) ([]common.Address, error) {
	// For Curve, the route is usually direct within a multi-token stable pool
	// For now, return the token pair as a direct route
	return []common.Address{tokenIn, tokenOut}, nil
}

// ValidateSwap validates a swap before execution
func (r *CurveSwapRouter) ValidateSwap(tokenIn, tokenOut common.Address, amountIn *big.Int) error {
	if amountIn.Sign() <= 0 {
		return fmt.Errorf("amountIn must be positive")
	}

	if tokenIn == tokenOut {
		return fmt.Errorf("tokenIn and tokenOut cannot be the same")
	}

	if tokenIn == common.HexToAddress("0x0") || tokenOut == common.HexToAddress("0x0") {
		return fmt.Errorf("invalid token addresses")
	}

	return nil
}

// RegisterCurveWithRegistry registers Curve implementation with the exchange registry
func RegisterCurveWithRegistry(registry *ExchangeRegistry) error {
	config := &ExchangeConfig{
		Type:                   math.ExchangeCurve,
		Name:                   "Curve",
		FactoryAddress:         common.HexToAddress("0xb9fc157394af804a3578134a6585c0dc9cc990d4"), // Curve Factory
		RouterAddress:          common.HexToAddress("0x90d12d24ff684b6ae6d2c8ca6ad8e0c7e7ab0675"), // Curve Router placeholder
		PoolInitCodeHash:       "",
		SwapSelector:           []byte{0x5b, 0x40, 0x2d, 0x3c}, // exchange
		StableSwapSelector:     []byte{0x79, 0x1a, 0xc9, 0x47}, // exchange_underlying
		ChainID:                1,                              // Ethereum mainnet
		SupportsFlashSwaps:     false,
		RequiresApproval:       true,
		MaxHops:                2,
		DefaultSlippagePercent: 0.1,
		Url:                    "https://curve.fi",
		ApiUrl:                 "https://api.curve.fi",
	}

	registry.exchanges[math.ExchangeCurve] = config

	// Register the implementations as well
	return nil
}