package execution

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

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

	"github.com/your-org/mev-bot/pkg/arbitrage"
)

// UniswapV3 SwapRouter address on Arbitrum
var UniswapV3SwapRouterAddress = common.HexToAddress("0xE592427A0AEce92De3Edee1F18E0157C05861564")

// UniswapV3Encoder encodes transactions for UniswapV3
type UniswapV3Encoder struct {
	swapRouterAddress common.Address
}

// NewUniswapV3Encoder creates a new UniswapV3 encoder
func NewUniswapV3Encoder() *UniswapV3Encoder {
	return &UniswapV3Encoder{
		swapRouterAddress: UniswapV3SwapRouterAddress,
	}
}

// ExactInputSingleParams represents parameters for exactInputSingle
type ExactInputSingleParams struct {
	TokenIn           common.Address
	TokenOut          common.Address
	Fee               uint32
	Recipient         common.Address
	Deadline          *big.Int
	AmountIn          *big.Int
	AmountOutMinimum  *big.Int
	SqrtPriceLimitX96 *big.Int
}

// EncodeSwap encodes a single UniswapV3 swap
func (e *UniswapV3Encoder) EncodeSwap(
	tokenIn common.Address,
	tokenOut common.Address,
	amountIn *big.Int,
	minAmountOut *big.Int,
	poolAddress common.Address,
	fee uint32,
	recipient common.Address,
	deadline time.Time,
) (common.Address, []byte, error) {
	// exactInputSingle((address,address,uint24,address,uint256,uint256,uint256,uint160))
	methodID := crypto.Keccak256([]byte("exactInputSingle((address,address,uint24,address,uint256,uint256,uint256,uint160))"))[:4]

	data := make([]byte, 0)
	data = append(data, methodID...)

	// Struct offset (always 32 bytes for single struct parameter)
	data = append(data, padLeft(big.NewInt(32).Bytes(), 32)...)

	// TokenIn
	data = append(data, padLeft(tokenIn.Bytes(), 32)...)

	// TokenOut
	data = append(data, padLeft(tokenOut.Bytes(), 32)...)

	// Fee (uint24)
	data = append(data, padLeft(big.NewInt(int64(fee)).Bytes(), 32)...)

	// Recipient
	data = append(data, padLeft(recipient.Bytes(), 32)...)

	// Deadline
	deadlineUnix := big.NewInt(deadline.Unix())
	data = append(data, padLeft(deadlineUnix.Bytes(), 32)...)

	// AmountIn
	data = append(data, padLeft(amountIn.Bytes(), 32)...)

	// AmountOutMinimum
	data = append(data, padLeft(minAmountOut.Bytes(), 32)...)

	// SqrtPriceLimitX96 (0 = no limit)
	data = append(data, padLeft(big.NewInt(0).Bytes(), 32)...)

	return e.swapRouterAddress, data, nil
}

// EncodeMultiHopSwap encodes a multi-hop UniswapV3 swap using exactInput
func (e *UniswapV3Encoder) EncodeMultiHopSwap(
	opp *arbitrage.Opportunity,
	recipient common.Address,
	minAmountOut *big.Int,
	deadline time.Time,
) (common.Address, []byte, error) {
	if len(opp.Path) < 2 {
		return common.Address{}, nil, fmt.Errorf("multi-hop requires at least 2 steps")
	}

	// Build encoded path for UniswapV3
	// Format: tokenIn | fee | tokenOut | fee | tokenOut | ...
	encodedPath := e.buildEncodedPath(opp)

	// exactInput((bytes,address,uint256,uint256,uint256))
	methodID := crypto.Keccak256([]byte("exactInput((bytes,address,uint256,uint256,uint256))"))[:4]

	data := make([]byte, 0)
	data = append(data, methodID...)

	// Struct offset
	data = append(data, padLeft(big.NewInt(32).Bytes(), 32)...)

	// Offset to path bytes (5 * 32 bytes)
	data = append(data, padLeft(big.NewInt(160).Bytes(), 32)...)

	// Recipient
	data = append(data, padLeft(recipient.Bytes(), 32)...)

	// Deadline
	deadlineUnix := big.NewInt(deadline.Unix())
	data = append(data, padLeft(deadlineUnix.Bytes(), 32)...)

	// AmountIn
	data = append(data, padLeft(opp.InputAmount.Bytes(), 32)...)

	// AmountOutMinimum
	data = append(data, padLeft(minAmountOut.Bytes(), 32)...)

	// Path bytes length
	data = append(data, padLeft(big.NewInt(int64(len(encodedPath))).Bytes(), 32)...)

	// Path bytes (padded to 32-byte boundary)
	data = append(data, encodedPath...)

	// Pad path to 32-byte boundary
	remainder := len(encodedPath) % 32
	if remainder != 0 {
		padding := make([]byte, 32-remainder)
		data = append(data, padding...)
	}

	return e.swapRouterAddress, data, nil
}

// buildEncodedPath builds the encoded path for UniswapV3 multi-hop swaps
func (e *UniswapV3Encoder) buildEncodedPath(opp *arbitrage.Opportunity) []byte {
	// Format: token (20 bytes) | fee (3 bytes) | token (20 bytes) | fee (3 bytes) | ...
	// Total: 20 + (23 * (n-1)) bytes for n tokens

	path := make([]byte, 0)

	// First token
	path = append(path, opp.Path[0].TokenIn.Bytes()...)

	// For each step, append fee + tokenOut
	for _, step := range opp.Path {
		// Fee (3 bytes, uint24)
		fee := make([]byte, 3)
		feeInt := big.NewInt(int64(step.Fee))
		feeBytes := feeInt.Bytes()
		copy(fee[3-len(feeBytes):], feeBytes)
		path = append(path, fee...)

		// TokenOut (20 bytes)
		path = append(path, step.TokenOut.Bytes()...)
	}

	return path
}

// EncodeExactOutput encodes an exactOutputSingle swap (output amount specified)
func (e *UniswapV3Encoder) EncodeExactOutput(
	tokenIn common.Address,
	tokenOut common.Address,
	amountOut *big.Int,
	maxAmountIn *big.Int,
	fee uint32,
	recipient common.Address,
	deadline time.Time,
) (common.Address, []byte, error) {
	// exactOutputSingle((address,address,uint24,address,uint256,uint256,uint256,uint160))
	methodID := crypto.Keccak256([]byte("exactOutputSingle((address,address,uint24,address,uint256,uint256,uint256,uint160))"))[:4]

	data := make([]byte, 0)
	data = append(data, methodID...)

	// Struct offset
	data = append(data, padLeft(big.NewInt(32).Bytes(), 32)...)

	// TokenIn
	data = append(data, padLeft(tokenIn.Bytes(), 32)...)

	// TokenOut
	data = append(data, padLeft(tokenOut.Bytes(), 32)...)

	// Fee
	data = append(data, padLeft(big.NewInt(int64(fee)).Bytes(), 32)...)

	// Recipient
	data = append(data, padLeft(recipient.Bytes(), 32)...)

	// Deadline
	deadlineUnix := big.NewInt(deadline.Unix())
	data = append(data, padLeft(deadlineUnix.Bytes(), 32)...)

	// AmountOut
	data = append(data, padLeft(amountOut.Bytes(), 32)...)

	// AmountInMaximum
	data = append(data, padLeft(maxAmountIn.Bytes(), 32)...)

	// SqrtPriceLimitX96 (0 = no limit)
	data = append(data, padLeft(big.NewInt(0).Bytes(), 32)...)

	return e.swapRouterAddress, data, nil
}

// EncodeMulticall encodes multiple calls into a single transaction
func (e *UniswapV3Encoder) EncodeMulticall(
	calls [][]byte,
	deadline time.Time,
) (common.Address, []byte, error) {
	// multicall(uint256 deadline, bytes[] data)
	methodID := crypto.Keccak256([]byte("multicall(uint256,bytes[])"))[:4]

	data := make([]byte, 0)
	data = append(data, methodID...)

	// Deadline
	deadlineUnix := big.NewInt(deadline.Unix())
	data = append(data, padLeft(deadlineUnix.Bytes(), 32)...)

	// Offset to bytes array (64 bytes: 32 for deadline + 32 for offset)
	data = append(data, padLeft(big.NewInt(64).Bytes(), 32)...)

	// Array length
	data = append(data, padLeft(big.NewInt(int64(len(calls))).Bytes(), 32)...)

	// Calculate offsets for each call
	currentOffset := int64(32 * len(calls)) // Space for all offsets
	offsets := make([]int64, len(calls))

	for i, call := range calls {
		offsets[i] = currentOffset
		// Each call takes: 32 bytes for length + length (padded to 32)
		currentOffset += 32 + int64((len(call)+31)/32*32)
	}

	// Write offsets
	for _, offset := range offsets {
		data = append(data, padLeft(big.NewInt(offset).Bytes(), 32)...)
	}

	// Write call data
	for _, call := range calls {
		// Length
		data = append(data, padLeft(big.NewInt(int64(len(call))).Bytes(), 32)...)

		// Data
		data = append(data, call...)

		// Padding
		remainder := len(call) % 32
		if remainder != 0 {
			padding := make([]byte, 32-remainder)
			data = append(data, padding...)
		}
	}

	return e.swapRouterAddress, data, nil
}