DeFi Trading Platform

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.19;

contract AMMPool {
    uint256 public constant MINIMUM_LIQUIDITY = 10**3;
    
    function swap(
        uint256 amountIn,
        uint256 amountOutMin,
        address tokenIn,
        address tokenOut,
        address to
    ) external returns (uint256 amountOut) {
        require(amountIn > 0, "Insufficient input amount");
        
        (uint256 reserveIn, uint256 reserveOut) = getReserves(tokenIn, tokenOut);
        
        // Calculate output amount using constant product formula
        amountOut = getAmountOut(amountIn, reserveIn, reserveOut);
        require(amountOut >= amountOutMin, "Insufficient output amount");
        
        // Execute swap
        IERC20(tokenIn).transferFrom(msg.sender, address(this), amountIn);
        IERC20(tokenOut).transfer(to, amountOut);
        
        emit Swap(msg.sender, tokenIn, tokenOut, amountIn, amountOut);
    }
    
    function getAmountOut(
        uint256 amountIn,
        uint256 reserveIn,
        uint256 reserveOut
    ) public pure returns (uint256 amountOut) {
        uint256 amountInWithFee = amountIn * 997; // 0.3% fee
        uint256 numerator = amountInWithFee * reserveOut;
        uint256 denominator = (reserveIn * 1000) + amountInWithFee;
        amountOut = numerator / denominator;
    }
}

import { useState, useCallback } from 'react';
import { useSwap } from '../hooks/useSwap';
import { useTokenBalance } from '../hooks/useTokenBalance';

export const SwapComponent: React.FC = () => {
  const [amountIn, setAmountIn] = useState('');
  const [tokenIn, setTokenIn] = useState('ETH');
  const [tokenOut, setTokenOut] = useState('USDC');
  
  const { swap, isLoading, estimateGas } = useSwap();
  const balance = useTokenBalance(tokenIn);
  
  const handleSwap = useCallback(async () => {
    try {
      const gasEstimate = await estimateGas(amountIn, tokenIn, tokenOut);
      await swap({
        amountIn,
        tokenIn,
        tokenOut,
        slippage: 0.5, // 0.5%
        gasLimit: gasEstimate * 1.2
      });
    } catch (error) {
      console.error('Swap failed:', error);
    }
  }, [amountIn, tokenIn, tokenOut, swap, estimateGas]);
  
  return (
    <div className="swap-container">
      <TokenInput
        value={amountIn}
        onChange={setAmountIn}
        token={tokenIn}
        onTokenChange={setTokenIn}
        balance={balance}
      />
      <SwapButton onClick={handleSwap} disabled={isLoading} />
    </div>
  );
};