DeFi Protocol Architecture: Building Uniswap & SushiSwap Clones

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import "@openzeppelin/contracts/token/ERC20/ERC20.sol";
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts/security/ReentrancyGuard.sol";

contract LiquidityPool is ERC20, ReentrancyGuard {
    IERC20 public token0;
    IERC20 public token1;
    
    uint256 public reserve0;
    uint256 public reserve1;
    
    uint256 public constant MINIMUM_LIQUIDITY = 1000;
    uint256 private unlocked = 1;
    
    event Mint(address indexed sender, uint256 amount0, uint256 amount1);
    event Burn(address indexed sender, uint256 amount0, uint256 amount1, address indexed to);
    event Swap(
        address indexed sender,
        uint256 amount0In,
        uint256 amount1In,
        uint256 amount0Out,
        uint256 amount1Out,
        address indexed to
    );
    event Sync(uint256 reserve0, uint256 reserve1);
    
    constructor(address _token0, address _token1) ERC20("LP Token", "LP") {
        token0 = IERC20(_token0);
        token1 = IERC20(_token1);
    }
    
    modifier lock() {
        require(unlocked == 1, "LOCKED");
        unlocked = 0;
        _;
        unlocked = 1;
    }
    
    // Add liquidity to the pool
    function mint(address to) external lock returns (uint256 liquidity) {
        uint256 balance0 = token0.balanceOf(address(this));
        uint256 balance1 = token1.balanceOf(address(this));
        
        uint256 amount0 = balance0 - reserve0;
        uint256 amount1 = balance1 - reserve1;
        
        if (totalSupply() == 0) {
            liquidity = sqrt(amount0 * amount1) - MINIMUM_LIQUIDITY;
            _mint(address(0), MINIMUM_LIQUIDITY);
        } else {
            liquidity = min(
                (amount0 * totalSupply()) / reserve0,
                (amount1 * totalSupply()) / reserve1
            );
        }
        
        require(liquidity > 0, "INSUFFICIENT_LIQUIDITY_MINTED");
        _mint(to, liquidity);
        
        _update(balance0, balance1);
        emit Mint(msg.sender, amount0, amount1);
    }
    
    // Remove liquidity from the pool
    function burn(address to) external lock returns (uint256 amount0, uint256 amount1) {
        uint256 balance0 = token0.balanceOf(address(this));
        uint256 balance1 = token1.balanceOf(address(this));
        
        uint256 liquidity = balanceOf(address(this));
        
        amount0 = (liquidity * balance0) / totalSupply();
        amount1 = (liquidity * balance1) / totalSupply();
        
        require(amount0 > 0 && amount1 > 0, "INSUFFICIENT_LIQUIDITY_BURNED");
        
        _burn(address(this), liquidity);
        token0.transfer(to, amount0);
        token1.transfer(to, amount1);
        
        balance0 = token0.balanceOf(address(this));
        balance1 = token1.balanceOf(address(this));
        
        _update(balance0, balance1);
        emit Burn(msg.sender, amount0, amount1, to);
    }
    
    // Swap tokens
    function swap(
        uint256 amount0Out,
        uint256 amount1Out,
        address to,
        bytes calldata data
    ) external lock {
        require(amount0Out > 0 || amount1Out > 0, "INSUFFICIENT_OUTPUT_AMOUNT");
        require(amount0Out < reserve0 && amount1Out < reserve1, "INSUFFICIENT_LIQUIDITY");
        
        if (amount0Out > 0) token0.transfer(to, amount0Out);
        if (amount1Out > 0) token1.transfer(to, amount1Out);
        
        uint256 balance0 = token0.balanceOf(address(this));
        uint256 balance1 = token1.balanceOf(address(this));
        
        uint256 amount0In = balance0 > reserve0 - amount0Out ? balance0 - (reserve0 - amount0Out) : 0;
        uint256 amount1In = balance1 > reserve1 - amount1Out ? balance1 - (reserve1 - amount1Out) : 0;
        
        require(amount0In > 0 || amount1In > 0, "INSUFFICIENT_INPUT_AMOUNT");
        
        // Check constant product formula: (x + dx) * (y - dy) >= x * y
        uint256 balance0Adjusted = (balance0 * 1000) - (amount0In * 3);
        uint256 balance1Adjusted = (balance1 * 1000) - (amount1In * 3);
        
        require(
            balance0Adjusted * balance1Adjusted >= uint256(reserve0) * uint256(reserve1) * 1000000,
            "K"
        );
        
        _update(balance0, balance1);
        emit Swap(msg.sender, amount0In, amount1In, amount0Out, amount1Out, to);
    }
    
    function _update(uint256 balance0, uint256 balance1) private {
        reserve0 = balance0;
        reserve1 = balance1;
        emit Sync(reserve0, reserve1);
    }
    
    function sqrt(uint256 y) internal pure returns (uint256 z) {
        if (y > 3) {
            z = y;
            uint256 x = y / 2 + 1;
            while (x < z) {
                z = x;
                x = (y / x + x) / 2;
            }
        } else if (y != 0) {
            z = 1;
        }
    }
    
    function min(uint256 a, uint256 b) internal pure returns (uint256) {
        return a < b ? a : b;
    }
}

pragma solidity ^0.8.0;

interface ILiquidityPool {
    function swap(uint256 amount0Out, uint256 amount1Out, address to, bytes calldata data) external;
    function token0() external view returns (address);
    function token1() external view returns (address);
    function getReserves() external view returns (uint256, uint256);
}

contract Router {
    address[] public pools;
    
    function getAmountOut(
        uint256 amountIn,
        uint256 reserveIn,
        uint256 reserveOut
    ) public pure returns (uint256 amountOut) {
        require(amountIn > 0, "INSUFFICIENT_INPUT_AMOUNT");
        require(reserveIn > 0 && reserveOut > 0, "INSUFFICIENT_LIQUIDITY");
        
        uint256 amountInWithFee = amountIn * 997;
        uint256 numerator = amountInWithFee * reserveOut;
        uint256 denominator = (reserveIn * 1000) + amountInWithFee;
        amountOut = numerator / denominator;
    }
    
    function swapExactTokensForTokens(
        uint256 amountIn,
        uint256 amountOutMin,
        address[] calldata path,
        address to,
        uint256 deadline
    ) external returns (uint256[] memory amounts) {
        require(deadline >= block.timestamp, "EXPIRED");
        
        amounts = new uint256[](path.length);
        amounts[0] = amountIn;
        
        for (uint256 i = 0; i < path.length - 1; i++) {
            // Calculate output amount for each hop
            // Execute swap through pool
        }
        
        require(amounts[amounts.length - 1] >= amountOutMin, "INSUFFICIENT_OUTPUT_AMOUNT");
    }
}

pragma solidity ^0.8.0;

import "@openzeppelin/contracts/token/ERC20/ERC20.sol";
import "@openzeppelin/contracts/governance/Governor.sol";

contract GovernanceToken is ERC20 {
    constructor() ERC20("Protocol Token", "PROTO") {
        _mint(msg.sender, 1_000_000 * 10 ** 18);
    }
}

contract ProtocolGovernor is Governor {
    constructor(IVotes _token)
        Governor("Protocol Governor")
        GovernorSettings(
            1,      // voting delay (1 block)
            50400,  // voting period (1 week)
            100e18  // proposal threshold
        )
    {}
    
    function votingDelay() public pure override returns (uint256) {
        return 1;
    }
    
    function votingPeriod() public pure override returns (uint256) {
        return 50400;
    }
    
    function quorumNumerator() public pure override returns (uint256) {
        return 4; // 4% quorum
    }
}

pragma solidity ^0.8.0;

interface IFlashLoanReceiver {
    function executeOperation(
        address asset,
        uint256 amount,
        uint256 premium,
        address initiator,
        bytes calldata params
    ) external returns (bytes32);
}

contract FlashLoanPool {
    uint256 public constant FLASH_LOAN_FEE = 9; // 0.09%
    
    function flashLoan(
        address receiver,
        address token,
        uint256 amount,
        bytes calldata params
    ) external {
        uint256 balance = IERC20(token).balanceOf(address(this));
        require(balance >= amount, "INSUFFICIENT_BALANCE");
        
        uint256 fee = (amount * FLASH_LOAN_FEE) / 10000;
        
        IERC20(token).transfer(receiver, amount);
        
        IFlashLoanReceiver(receiver).executeOperation(
            token,
            amount,
            fee,
            msg.sender,
            params
        );
        
        require(
            IERC20(token).balanceOf(address(this)) >= balance + fee,
            "FLASH_LOAN_NOT_REPAID"
        );
    }
}

pragma solidity ^0.8.0;

struct Position {
    uint128 liquidity;
    uint256 feeGrowthInside0LastX128;
    uint256 feeGrowthInside1LastX128;
    uint128 tokensOwed0;
    uint128 tokensOwed1;
}

contract ConcentratedLiquidityPool {
    mapping(uint256 => Position) public positions;
    
    function mint(
        int24 tickLower,
        int24 tickUpper,
        uint128 amount,
        bytes calldata data
    ) external returns (uint256 tokenId) {
        // Calculate liquidity for price range
        // Update position state
        // Collect tokens from user
    }
    
    function burn(
        uint256 tokenId,
        uint128 liquidity
    ) external returns (uint256 amount0, uint256 amount1) {
        // Remove liquidity from position
        // Calculate fees earned
        // Return tokens to user
    }
}

LiquidityPool pool = new LiquidityPool(
    address(USDC),
    address(ETH)
);

// Approve tokens
USDC.approve(address(pool), 1_000_000e6);
ETH.approve(address(pool), 1000e18);

// Add initial liquidity
pool.mint(msg.sender);

// User swaps 100 USDC for ETH
USDC.approve(address(router), 100e6);
router.swapExactTokensForTokens(
    100e6,
    95e18,  // minimum ETH output
    [USDC, ETH],
    msg.sender,
    block.timestamp + 300
);