// SPDX-License-Identifier: MIT pragma solidity ^0.8.19; import "@openzeppelin/contracts/token/ERC20/IERC20.sol"; import "@openzeppelin/contracts/token/ERC20/ERC20.sol"; import "@openzeppelin/contracts/utils/ReentrancyGuard.sol"; import "@openzeppelin/contracts/utils/math/Math.sol"; /** * @title MiniSwapAMM * @dev 简单的自动做市商 (AMM) 实现，基于 x * y = k 公式 */ contract MiniSwapAMM is ERC20, ReentrancyGuard { IERC20 public immutable tokenA; IERC20 public immutable tokenB; uint256 public reserveA; uint256 public reserveB; uint256 private constant MINIMUM_LIQUIDITY = 10**3; event AddLiquidity( address indexed provider, uint256 amountA, uint256 amountB, uint256 liquidity ); event RemoveLiquidity( address indexed provider, uint256 amountA, uint256 amountB, uint256 liquidity ); event Swap( address indexed trader, address tokenIn, address tokenOut, uint256 amountIn, uint256 amountOut ); constructor(address _tokenA, address _tokenB) ERC20("MiniSwap LP Token", "MSLP") { tokenA = IERC20(_tokenA); tokenB = IERC20(_tokenB); } /** * @dev 添加流动性 * @param amountADesired 期望添加的 tokenA 数量 * @param amountBDesired 期望添加的 tokenB 数量 * @param amountAMin 最小添加的 tokenA 数量 * @param amountBMin 最小添加的 tokenB 数量 * @return amountA 实际添加的 tokenA 数量 * @return amountB 实际添加的 tokenB 数量 * @return liquidity 获得的 LP 代币数量 */ function addLiquidity( uint256 amountADesired, uint256 amountBDesired, uint256 amountAMin, uint256 amountBMin ) external nonReentrant returns (uint256 amountA, uint256 amountB, uint256 liquidity) { (amountA, amountB) = _calculateOptimalAmounts( amountADesired, amountBDesired, amountAMin, amountBMin ); // 转移代币到合约 tokenA.transferFrom(msg.sender, address(this), amountA); tokenB.transferFrom(msg.sender, address(this), amountB); liquidity = _mintLiquidity(amountA, amountB); emit AddLiquidity(msg.sender, amountA, amountB, liquidity); } /** * @dev 移除流动性 * @param liquidity 要移除的 LP 代币数量 * @param amountAMin 最小获得的 tokenA 数量 * @param amountBMin 最小获得的 tokenB 数量 * @return amountA 获得的 tokenA 数量 * @return amountB 获得的 tokenB 数量 */ function removeLiquidity( uint256 liquidity, uint256 amountAMin, uint256 amountBMin ) external nonReentrant returns (uint256 amountA, uint256 amountB) { require(liquidity > 0, "MiniSwapAMM: INSUFFICIENT_LIQUIDITY"); uint256 totalSupply = totalSupply(); amountA = (liquidity * reserveA) / totalSupply; amountB = (liquidity * reserveB) / totalSupply; require(amountA >= amountAMin, "MiniSwapAMM: INSUFFICIENT_A_AMOUNT"); require(amountB >= amountBMin, "MiniSwapAMM: INSUFFICIENT_B_AMOUNT"); _burn(msg.sender, liquidity); tokenA.transfer(msg.sender, amountA); tokenB.transfer(msg.sender, amountB); _updateReserves(); emit RemoveLiquidity(msg.sender, amountA, amountB, liquidity); } /** * @dev 交换代币 A 到代币 B * @param amountAIn 输入的 tokenA 数量 * @param amountBOutMin 最小输出的 tokenB 数量 * @return amountBOut 实际输出的 tokenB 数量 */ function swapAForB(uint256 amountAIn, uint256 amountBOutMin) external nonReentrant returns (uint256 amountBOut) { require(amountAIn > 0, "MiniSwapAMM: INSUFFICIENT_INPUT_AMOUNT"); amountBOut = getAmountOut(amountAIn, reserveA, reserveB); require(amountBOut >= amountBOutMin, "MiniSwapAMM: INSUFFICIENT_OUTPUT_AMOUNT"); tokenA.transferFrom(msg.sender, address(this), amountAIn); tokenB.transfer(msg.sender, amountBOut); _updateReserves(); emit Swap(msg.sender, address(tokenA), address(tokenB), amountAIn, amountBOut); } /** * @dev 交换代币 B 到代币 A * @param amountBIn 输入的 tokenB 数量 * @param amountAOutMin 最小输出的 tokenA 数量 * @return amountAOut 实际输出的 tokenA 数量 */ function swapBForA(uint256 amountBIn, uint256 amountAOutMin) external nonReentrant returns (uint256 amountAOut) { require(amountBIn > 0, "MiniSwapAMM: INSUFFICIENT_INPUT_AMOUNT"); amountAOut = getAmountOut(amountBIn, reserveB, reserveA); require(amountAOut >= amountAOutMin, "MiniSwapAMM: INSUFFICIENT_OUTPUT_AMOUNT"); tokenB.transferFrom(msg.sender, address(this), amountBIn); tokenA.transfer(msg.sender, amountAOut); _updateReserves(); emit Swap(msg.sender, address(tokenB), address(tokenA), amountBIn, amountAOut); } /** * @dev 根据输入数量计算输出数量 (基于 x * y = k 公式) * @param amountIn 输入数量 * @param reserveIn 输入代币储备量 * @param reserveOut 输出代币储备量 * @return amountOut 输出数量 */ function getAmountOut(uint256 amountIn, uint256 reserveIn, uint256 reserveOut) public pure returns (uint256 amountOut) { require(amountIn > 0, "MiniSwapAMM: INSUFFICIENT_INPUT_AMOUNT"); require(reserveIn > 0 && reserveOut > 0, "MiniSwapAMM: INSUFFICIENT_LIQUIDITY"); // 考虑 0.3% 的交易费用 uint256 amountInWithFee = amountIn * 997; uint256 numerator = amountInWithFee * reserveOut; uint256 denominator = (reserveIn * 1000) + amountInWithFee; amountOut = numerator / denominator; } /** * @dev 获取当前储备量 */ function getReserves() external view returns (uint256 _reserveA, uint256 _reserveB) { return (reserveA, reserveB); } /** * @dev 计算最优的代币数量比例 */ function _calculateOptimalAmounts( uint256 amountADesired, uint256 amountBDesired, uint256 amountAMin, uint256 amountBMin ) internal view returns (uint256 amountA, uint256 amountB) { if (reserveA == 0 && reserveB == 0) { // 首次添加流动性 return (amountADesired, amountBDesired); } else { uint256 amountBOptimal = (amountADesired * reserveB) / reserveA; if (amountBOptimal <= amountBDesired) { require(amountBOptimal >= amountBMin, "MiniSwapAMM: INSUFFICIENT_B_AMOUNT"); return (amountADesired, amountBOptimal); } else { uint256 amountAOptimal = (amountBDesired * reserveA) / reserveB; require(amountAOptimal <= amountADesired && amountAOptimal >= amountAMin, "MiniSwapAMM: INSUFFICIENT_A_AMOUNT"); return (amountAOptimal, amountBDesired); } } } /** * @dev 铸造流动性代币 */ function _mintLiquidity(uint256 amountA, uint256 amountB) internal returns (uint256 liquidity) { uint256 totalSupply = totalSupply(); if (totalSupply == 0) { // 首次添加流动性 liquidity = Math.sqrt(amountA * amountB); require(liquidity > MINIMUM_LIQUIDITY, "MiniSwapAMM: INSUFFICIENT_LIQUIDITY_MINTED"); // 从流动性中减去最小流动性，永久锁定 liquidity = liquidity - MINIMUM_LIQUIDITY; } else { liquidity = Math.min( (amountA * totalSupply) / reserveA, (amountB * totalSupply) / reserveB ); } require(liquidity > 0, "MiniSwapAMM: INSUFFICIENT_LIQUIDITY_MINTED"); _mint(msg.sender, liquidity); _updateReserves(); } /** * @dev 更新储备量 */ function _updateReserves() internal { reserveA = tokenA.balanceOf(address(this)); reserveB = tokenB.balanceOf(address(this)); } }