Looksrare合约讲解

Looksrare合约讲解

因为做了一个NFT市场，所以对opensea，rarible，looksrare合约都研究了下，记录如下

合约架构

https://etherscan.io/accounts/label/looksrare

三家的合约高度相似，只不过是将代码重构的好看一些。再加些最近才有的EIP。looksare基本上是把能拆的都拆了，比如手续费、版权（EIP2981）、transfer，对比下另外两家，舒服很多

业务逻辑

基本都是链下操作，只有在真正mint nft，撮合交易成功，取消交易才会上链。甚至现在mint nft都不上链，第一次transfer时才会mint nft。进一步减少gas消耗。
创建订单：使用订单参数+salt进行EIP712 signature，transfer时在合约中验证签名，这样能减少Gas和保证订单没问题。。。。。才怪，open就出了有人拿到signature后，等订单过期了再去调用合约，把人家的nft低价撸走的bug。
取消订单：链上不保存创建订单。就像上面说的，防止bug出现，就要链上保存取消的订单，但是opensea没有判断 currentTime>expireTime 所以拿过期的signature还是可以完成交易
取消所有订单，减少gas，理论上也不是取消所有，一次的上限是500000
版权费：使用EIP2981，原因是像opensea，有版权费上限，如果我要收100%的版权费，没辙，所以要一个链上保存版权费的功能

代码结构

共两个cancelOrder
三个撮合函数
好几个update周边合约函数
两个transfer token函数
一个transfer nft函数
一个校验函数

//取消订单
cancelAllOrdersForSender
cancelMultipleMakerOrders
//撮合函数
//卖家挂单
matchAskWithTakerBidUsingETHAndWETH
matchAskWithTakerBid
//买家询价
matchBidWithTakerAsk
//转钱
_transferFeesAndFunds
_transferFeesAndFundsWithWETH
//转nft
_transferNonFungibleToken
//校验订单
_validateOrder

从上面函数名可以看出，好几个都是相似的内容，所以合约还是比较容易看懂的

Exchange合约注释

因为做了一个NFT市场，所以对opensea，rarible，looksrare合约都研究了下，记录如下

合约架构

https://etherscan.io/accounts/label/looksrare

三家的合约高度相似，只不过是将代码重构的好看一些。再加些最近才有的EIP。looksare基本上是把能拆的都拆了，比如手续费、版权（EIP2981）、transfer，对比下另外两家，舒服很多

业务逻辑

基本都是链下操作，只有在真正mint nft，撮合交易成功，取消交易才会上链。甚至现在mint nft都不上链，第一次transfer时才会mint nft。进一步减少gas消耗。
创建订单：使用订单参数+salt进行EIP712 signature，transfer时在合约中验证签名，这样能减少Gas和保证订单没问题。。。。。才怪，open就出了有人拿到signature后，等订单过期了再去调用合约，把人家的nft低价撸走的bug。
取消订单：链上不保存创建订单。就像上面说的，防止bug出现，就要链上保存取消的订单，但是opensea没有判断 currentTime>expireTime 所以拿过期的signature还是可以完成交易
取消所有订单，减少gas，理论上也不是取消所有，一次的上限是500000
版权费：使用EIP2981，原因是像opensea，有版权费上限，如果我要收100%的版权费，没辙，所以要一个链上保存版权费的功能

代码结构

共两个cancelOrder
三个撮合函数
好几个update周边合约函数
两个transfer token函数
一个transfer nft函数
一个校验函数

//取消订单
cancelAllOrdersForSender
cancelMultipleMakerOrders
//撮合函数
//卖家挂单
matchAskWithTakerBidUsingETHAndWETH
matchAskWithTakerBid
//买家询价
matchBidWithTakerAsk
//转钱
_transferFeesAndFunds
_transferFeesAndFundsWithWETH
//转nft
_transferNonFungibleToken
//校验订单
_validateOrder

从上面函数名可以看出，好几个都是相似的内容，所以合约还是比较容易看懂的

Exchange合约注释

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

// OpenZeppelin contracts
import {Ownable} from "@openzeppelin/contracts/access/Ownable.sol";
import {ReentrancyGuard} from "@openzeppelin/contracts/security/ReentrancyGuard.sol";
import {IERC20, SafeERC20} from "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";

// LooksRare interfaces
import {ICurrencyManager} from "./interfaces/ICurrencyManager.sol";
import {IExecutionManager} from "./interfaces/IExecutionManager.sol";
import {IExecutionStrategy} from "./interfaces/IExecutionStrategy.sol";
import {IRoyaltyFeeManager} from "./interfaces/IRoyaltyFeeManager.sol";
import {ILooksRareExchange} from "./interfaces/ILooksRareExchange.sol";
import {ITransferManagerNFT} from "./interfaces/ITransferManagerNFT.sol";
import {ITransferSelectorNFT} from "./interfaces/ITransferSelectorNFT.sol";
import {IWETH} from "./interfaces/IWETH.sol";

// LooksRare libraries
import {OrderTypes} from "./libraries/OrderTypes.sol";
import {SignatureChecker} from "./libraries/SignatureChecker.sol";


contract LooksRareExchange is ILooksRareExchange, ReentrancyGuard, Ownable {
    using SafeERC20 for IERC20;
    //订单的卖家和买家信息
    using OrderTypes for OrderTypes.MakerOrder;
    using OrderTypes for OrderTypes.TakerOrder;
    //weth的地址
    address public immutable WETH;
    、、EIP712的信息
    bytes32 public immutable DOMAIN_SEPARATOR;
    //手续费地址
    address public protocolFeeRecipient;
    //looksrare的周边合约地址
    ICurrencyManager public currencyManager;
    IExecutionManager public executionManager;
    IRoyaltyFeeManager public royaltyFeeManager;
    ITransferSelectorNFT public transferSelectorNFT;
    //用于取消订单和校验订单是否合法的逻辑
    mapping(address => uint256) public userMinOrderNonce;
    mapping(address => mapping(uint256 => bool)) private _isUserOrderNonceExecutedOrCancelled;

    event CancelAllOrders(address indexed user, uint256 newMinNonce);
    event CancelMultipleOrders(address indexed user, uint256[] orderNonces);
    event NewCurrencyManager(address indexed currencyManager);
    event NewExecutionManager(address indexed executionManager);
    event NewProtocolFeeRecipient(address indexed protocolFeeRecipient);
    event NewRoyaltyFeeManager(address indexed royaltyFeeManager);
    event NewTransferSelectorNFT(address indexed transferSelectorNFT);

    event RoyaltyPayment(
        address indexed collection,
        uint256 indexed tokenId,
        address indexed royaltyRecipient,
        address currency,
        uint256 amount
    );

    event TakerAsk(
        bytes32 orderHash, // bid hash of the maker order
        uint256 orderNonce, // user order nonce
        address indexed taker, // sender address for the taker ask order
        address indexed maker, // maker address of the initial bid order
        address indexed strategy, // strategy that defines the execution
        address currency, // currency address
        address collection, // collection address
        uint256 tokenId, // tokenId transferred
        uint256 amount, // amount of tokens transferred
        uint256 price // final transacted price
    );

    event TakerBid(
        bytes32 orderHash, // ask hash of the maker order
        uint256 orderNonce, // user order nonce
        address indexed taker, // sender address for the taker bid order
        address indexed maker, // maker address of the initial ask order
        address indexed strategy, // strategy that defines the execution
        address currency, // currency address
        address collection, // collection address
        uint256 tokenId, // tokenId transferred
        uint256 amount, // amount of tokens transferred
        uint256 price // final transacted price
    );

    /**
     * @notice Constructor 保存好签名校验需要的参数，保存周边合约的地址
     * @param _currencyManager currency manager address
     * @param _executionManager execution manager address
     * @param _royaltyFeeManager royalty fee manager address
     * @param _WETH wrapped ether address (for other chains, use wrapped native asset)
     * @param _protocolFeeRecipient protocol fee recipient
     */
    constructor(
        address _currencyManager,
        address _executionManager,
        address _royaltyFeeManager,
        address _WETH,
        address _protocolFeeRecipient
    ) {
        // Calculate the domain separator
        DOMAIN_SEPARATOR = keccak256(
            abi.encode(
                0x8b73c3c69bb8fe3d512ecc4cf759cc79239f7b179b0ffacaa9a75d522b39400f, // keccak256("EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)")
                0xda9101ba92939daf4bb2e18cd5f942363b9297fbc3232c9dd964abb1fb70ed71, // keccak256("LooksRareExchange")
                0xc89efdaa54c0f20c7adf612882df0950f5a951637e0307cdcb4c672f298b8bc6, // keccak256(bytes("1")) for versionId = 1
                block.chainid,
                address(this)
            )
        );

        currencyManager = ICurrencyManager(_currencyManager);
        executionManager = IExecutionManager(_executionManager);
        royaltyFeeManager = IRoyaltyFeeManager(_royaltyFeeManager);
        WETH = _WETH;
        protocolFeeRecipient = _protocolFeeRecipient;
    }

    /**
     * @notice Cancel all pending orders for a sender
        取消所有订单
     * @param minNonce minimum user nonce
     */
    function cancelAllOrdersForSender(uint256 minNonce) external {
        require(minNonce > userMinOrderNonce[msg.sender], "Cancel: Order nonce lower than current");
        require(minNonce < userMinOrderNonce[msg.sender] + 500000, "Cancel: Cannot cancel more orders");
        userMinOrderNonce[msg.sender] = minNonce;

        emit CancelAllOrders(msg.sender, minNonce);
    }

    /**
     * @notice Cancel maker orders
      根据需要取消订单
     * @param orderNonces array of order nonces
     */
    function cancelMultipleMakerOrders(uint256[] calldata orderNonces) external {
        require(orderNonces.length > 0, "Cancel: Cannot be empty");

        for (uint256 i = 0; i < orderNonces.length; i++) {
            require(orderNonces[i] >= userMinOrderNonce[msg.sender], "Cancel: Order nonce lower than current");
            _isUserOrderNonceExecutedOrCancelled[msg.sender][orderNonces[i]] = true;
        }

        emit CancelMultipleOrders(msg.sender, orderNonces);
    }

    /**
     * @notice Match ask with a taker bid order using ETH
        核心exchange业务逻辑并且eth和weth混合支付，可能你的weth不足，不要紧，再用点eth，这里面会将eth换成weth，就不用你先去兑换了，节省gas
     * @param takerBid taker bid order
     * @param makerAsk maker ask order
     */
    function matchAskWithTakerBidUsingETHAndWETH(
        OrderTypes.TakerOrder calldata takerBid,
        OrderTypes.MakerOrder calldata makerAsk
    ) external payable override nonReentrant {
     //确定是卖家挂单才行，因为买家询价是不能用eth支付的
        require((makerAsk.isOrderAsk) && (!takerBid.isOrderAsk), "Order: Wrong sides");
        require(makerAsk.currency == WETH, "Order: Currency must be WETH");
        require(msg.sender == takerBid.taker, "Order: Taker must be the sender");
    //eth不足，先将weth转移给卖家
        // If not enough ETH to cover the price, use WETH
        if (takerBid.price > msg.value) {
            IERC20(WETH).safeTransferFrom(msg.sender, address(this), (takerBid.price - msg.value));
        } else {
            require(takerBid.price == msg.value, "Order: Msg.value too high");
        }
        //将eth兑换成weth来交易
        // Wrap ETH sent to this contract
        IWETH(WETH).deposit{value: msg.value}();
        //使用eip712校验订单
        // Check the maker ask order
        bytes32 askHash = makerAsk.hash();
        _validateOrder(makerAsk, askHash);
         //挂单，拍卖有不同的交易费费率，从这取出来
        // Retrieve execution parameters
        (bool isExecutionValid, uint256 tokenId, uint256 amount) = IExecutionStrategy(makerAsk.strategy)
            .canExecuteTakerBid(takerBid, makerAsk);

        require(isExecutionValid, "Strategy: Execution invalid");

        // Update maker ask order status to true (prevents replay)
        //先将订单置为已完成，防止重入
        _isUserOrderNonceExecutedOrCancelled[makerAsk.signer][makerAsk.nonce] = true;

        // Execution part 1/2
        //真正开始交易的地方，分两步，转移钱，再转移nft
        _transferFeesAndFundsWithWETH(
            makerAsk.strategy,
            makerAsk.collection,
            tokenId,
            makerAsk.signer,
            takerBid.price,
            makerAsk.minPercentageToAsk
        );

        // Execution part 2/2
        _transferNonFungibleToken(makerAsk.collection, makerAsk.signer, takerBid.taker, tokenId, amount);

        emit TakerBid(
            askHash,
            makerAsk.nonce,
            takerBid.taker,
            makerAsk.signer,
            makerAsk.strategy,
            makerAsk.currency,
            makerAsk.collection,
            tokenId,
            amount,
            takerBid.price
        );
    }

    /**
     * @notice Match a takerBid with a matchAsk
       基础撮合订单，和上面的区别就是这里只能用weth
     * @param takerBid taker bid order
     * @param makerAsk maker ask order
     */
    function matchAskWithTakerBid(OrderTypes.TakerOrder calldata takerBid, OrderTypes.MakerOrder calldata makerAsk)
        external
        override
        nonReentrant
    {
        require((makerAsk.isOrderAsk) && (!takerBid.isOrderAsk), "Order: Wrong sides");
        require(msg.sender == takerBid.taker, "Order: Taker must be the sender");

        // Check the maker ask order
        bytes32 askHash = makerAsk.hash();
        _validateOrder(makerAsk, askHash);

        (bool isExecutionValid, uint256 tokenId, uint256 amount) = IExecutionStrategy(makerAsk.strategy)
            .canExecuteTakerBid(takerBid, makerAsk);

        require(isExecutionValid, "Strategy: Execution invalid");

        // Update maker ask order status to true (prevents replay)
        _isUserOrderNonceExecutedOrCancelled[makerAsk.signer][makerAsk.nonce] = true;

        // Execution part 1/2
        _transferFeesAndFunds(
            makerAsk.strategy,
            makerAsk.collection,
            tokenId,
            makerAsk.currency,
            msg.sender,
            makerAsk.signer,
            takerBid.price,
            makerAsk.minPercentageToAsk
        );

        // Execution part 2/2
        _transferNonFungibleToken(makerAsk.collection, makerAsk.signer, takerBid.taker, tokenId, amount);

        emit TakerBid(
            askHash,
            makerAsk.nonce,
            takerBid.taker,
            makerAsk.signer,
            makerAsk.strategy,
            makerAsk.currency,
            makerAsk.collection,
            tokenId,
            amount,
            takerBid.price
        );
    }

    /**
     * @notice Match a takerAsk with a makerBid
        撮合订单，这里和上面一个的区别是这里是买家询价，上面是卖家挂单，这里的签名者是买家，上面的是卖家
     * @param takerAsk taker ask order
     * @param makerBid maker bid order
     */
    function matchBidWithTakerAsk(OrderTypes.TakerOrder calldata takerAsk, OrderTypes.MakerOrder calldata makerBid)
        external
        override
        nonReentrant
    {
        require((!makerBid.isOrderAsk) && (takerAsk.isOrderAsk), "Order: Wrong sides");
        require(msg.sender == takerAsk.taker, "Order: Taker must be the sender");

        // Check the maker bid order
        bytes32 bidHash = makerBid.hash();
        _validateOrder(makerBid, bidHash);

        (bool isExecutionValid, uint256 tokenId, uint256 amount) = IExecutionStrategy(makerBid.strategy)
            .canExecuteTakerAsk(takerAsk, makerBid);

        require(isExecutionValid, "Strategy: Execution invalid");

        // Update maker bid order status to true (prevents replay)
        _isUserOrderNonceExecutedOrCancelled[makerBid.signer][makerBid.nonce] = true;

        // Execution part 1/2
        _transferNonFungibleToken(makerBid.collection, msg.sender, makerBid.signer, tokenId, amount);

        // Execution part 2/2
        _transferFeesAndFunds(
            makerBid.strategy,
            makerBid.collection,
            tokenId,
            makerBid.currency,
            makerBid.signer,
            takerAsk.taker,
            takerAsk.price,
            takerAsk.minPercentageToAsk
        );

        emit TakerAsk(
            bidHash,
            makerBid.nonce,
            takerAsk.taker,
            makerBid.signer,
            makerBid.strategy,
            makerBid.currency,
            makerBid.collection,
            tokenId,
            amount,
            takerAsk.price
        );
    }
    //修改周边合约的地址，用于升级或者出bug用
    /**
     * @notice Update currency manager
     * @param _currencyManager new currency manager address
     */
    function updateCurrencyManager(address _currencyManager) external onlyOwner {
        require(_currencyManager != address(0), "Owner: Cannot be null address");
        currencyManager = ICurrencyManager(_currencyManager);
        emit NewCurrencyManager(_currencyManager);
    }

    /**
     * @notice Update execution manager
     * @param _executionManager new execution manager address
     */
    function updateExecutionManager(address _executionManager) external onlyOwner {
        require(_executionManager != address(0), "Owner: Cannot be null address");
        executionManager = IExecutionManager(_executionManager);
        emit NewExecutionManager(_executionManager);
    }

    /**
     * @notice Update protocol fee and recipient
     * @param _protocolFeeRecipient new recipient for protocol fees
     */
    function updateProtocolFeeRecipient(address _protocolFeeRecipient) external onlyOwner {
        protocolFeeRecipient = _protocolFeeRecipient;
        emit NewProtocolFeeRecipient(_protocolFeeRecipient);
    }

    /**
     * @notice Update royalty fee manager
     * @param _royaltyFeeManager new fee manager address
     */
    function updateRoyaltyFeeManager(address _royaltyFeeManager) external onlyOwner {
        require(_royaltyFeeManager != address(0), "Owner: Cannot be null address");
        royaltyFeeManager = IRoyaltyFeeManager(_royaltyFeeManager);
        emit NewRoyaltyFeeManager(_royaltyFeeManager);
    }

    /**
     * @notice Update transfer selector NFT
     * @param _transferSelectorNFT new transfer selector address
     */
    function updateTransferSelectorNFT(address _transferSelectorNFT) external onlyOwner {
        require(_transferSelectorNFT != address(0), "Owner: Cannot be null address");
        transferSelectorNFT = ITransferSelectorNFT(_transferSelectorNFT);

        emit NewTransferSelectorNFT(_transferSelectorNFT);
    }

    //订单是否取消
    /**
     * @notice Check whether user order nonce is executed or cancelled
     * @param user address of user
     * @param orderNonce nonce of the order
     */
    function isUserOrderNonceExecutedOrCancelled(address user, uint256 orderNonce) external view returns (bool) {
        return _isUserOrderNonceExecutedOrCancelled[user][orderNonce];
    }


    /**
       N个费用处理，转移钱，用传入的代币交易
     * @notice Transfer fees and funds to royalty recipient, protocol, and seller
     * @param strategy address of the execution strategy
     * @param collection non fungible token address for the transfer
     * @param tokenId tokenId
     * @param currency currency being used for the purchase (e.g., WETH/USDC)
     * @param from sender of the funds
     * @param to seller's recipient
     * @param amount amount being transferred (in currency)
     * @param minPercentageToAsk minimum percentage of the gross amount that goes to ask
     */
    function _transferFeesAndFunds(
        address strategy,
        address collection,
        uint256 tokenId,
        address currency,
        address from,
        address to,
        uint256 amount,
        uint256 minPercentageToAsk
    ) internal {
        // Initialize the final amount that is transferred to seller
        //最终的给卖家的钱，会经过一层又一层的吃拿卡要
        uint256 finalSellerAmount = amount;

        // 1. Protocol fee 官方手续费
        {
            uint256 protocolFeeAmount = _calculateProtocolFee(strategy, amount);

            // Check if the protocol fee is different than 0 for this strategy
            if ((protocolFeeRecipient != address(0)) && (protocolFeeAmount != 0)) {
                IERC20(currency).safeTransferFrom(from, protocolFeeRecipient, protocolFeeAmount);
                finalSellerAmount -= protocolFeeAmount;
            }
        }

        // 2. Royalty fee 版权费
        {
            (address royaltyFeeRecipient, uint256 royaltyFeeAmount) = royaltyFeeManager
                .calculateRoyaltyFeeAndGetRecipient(collection, tokenId, amount);

            // Check if there is a royalty fee and that it is different to 0
            if ((royaltyFeeRecipient != address(0)) && (royaltyFeeAmount != 0)) {
                IERC20(currency).safeTransferFrom(from, royaltyFeeRecipient, royaltyFeeAmount);
                finalSellerAmount -= royaltyFeeAmount;

                emit RoyaltyPayment(collection, tokenId, royaltyFeeRecipient, currency, royaltyFeeAmount);
            }
        }

        //保证给卖家的钱的最小值，要有人性，手动狗头
        require((finalSellerAmount * 10000) >= (minPercentageToAsk * amount), "Fees: Higher than expected");

        // 3. Transfer final amount (post-fees) to seller
        {
            IERC20(currency).safeTransferFrom(from, to, finalSellerAmount);
        }
    }

    /**
      和上面的类似，只是用了weth
     * @notice Transfer fees and funds to royalty recipient, protocol, and seller
     * @param strategy address of the execution strategy
     * @param collection non fungible token address for the transfer
     * @param tokenId tokenId
     * @param to seller's recipient
     * @param amount amount being transferred (in currency)
     * @param minPercentageToAsk minimum percentage of the gross amount that goes to ask
     */
    function _transferFeesAndFundsWithWETH(
        address strategy,
        address collection,
        uint256 tokenId,
        address to,
        uint256 amount,
        uint256 minPercentageToAsk
    ) internal {
        // Initialize the final amount that is transferred to seller
        uint256 finalSellerAmount = amount;

        // 1. Protocol fee
        {
            uint256 protocolFeeAmount = _calculateProtocolFee(strategy, amount);

            // Check if the protocol fee is different than 0 for this strategy
            if ((protocolFeeRecipient != address(0)) && (protocolFeeAmount != 0)) {
                IERC20(WETH).safeTransfer(protocolFeeRecipient, protocolFeeAmount);
                finalSellerAmount -= protocolFeeAmount;
            }
        }

        // 2. Royalty fee
        {
            (address royaltyFeeRecipient, uint256 royaltyFeeAmount) = royaltyFeeManager
                .calculateRoyaltyFeeAndGetRecipient(collection, tokenId, amount);

            // Check if there is a royalty fee and that it is different to 0
            if ((royaltyFeeRecipient != address(0)) && (royaltyFeeAmount != 0)) {
                IERC20(WETH).safeTransfer(royaltyFeeRecipient, royaltyFeeAmount);
                finalSellerAmount -= royaltyFeeAmount;

                emit RoyaltyPayment(collection, tokenId, royaltyFeeRecipient, address(WETH), royaltyFeeAmount);
            }
        }

        require((finalSellerAmount * 10000) >= (minPercentageToAsk * amount), "Fees: Higher than expected");

        // 3. Transfer final amount (post-fees) to seller
        {
            IERC20(WETH).safeTransfer(to, finalSellerAmount);
        }
    }

    /**
     * @notice Transfer NFT
        那到官方规定的NFT转移合约，转移NFT
     * @param collection address of the token collection
     * @param from address of the sender
     * @param to address of the recipient
     * @param tokenId tokenId
     * @param amount amount of tokens (1 for ERC721, 1+ for ERC1155)
     * @dev For ERC721, amount is not used
     */
    function _transferNonFungibleToken(
        address collection,
        address from,
        address to,
        uint256 tokenId,
        uint256 amount
    ) internal {
        // Retrieve the transfer manager address
        address transferManager = transferSelectorNFT.checkTransferManagerForToken(collection);

        // If no transfer manager found, it returns address(0)
        require(transferManager != address(0), "Transfer: No NFT transfer manager available");

        // If one is found, transfer the token
        ITransferManagerNFT(transferManager).transferNonFungibleToken(collection, from, to, tokenId, amount);
    }

    /**
     * @notice Calculate protocol fee for an execution strategy
     * @param executionStrategy strategy
     * @param amount amount to transfer
     */
    function _calculateProtocolFee(address executionStrategy, uint256 amount) internal view returns (uint256) {
        uint256 protocolFee = IExecutionStrategy(executionStrategy).viewProtocolFee();
        return (protocolFee * amount) / 10000;
    }

    /**
        校验订单
     * @notice Verify the validity of the maker order
     * @param makerOrder maker order
     * @param orderHash computed hash for the order
     */
    function _validateOrder(OrderTypes.MakerOrder calldata makerOrder, bytes32 orderHash) internal view {
        // Verify whether order nonce has expired
        require(
  //订单是否取消，并且订单的nonce>合约记录的订单签名者的nonce值，因为可能其他人恶意取消订单，这里取签名者保证别人恶意取消没用       (!_isUserOrderNonceExecutedOrCancelled[makerOrder.signer][makerOrder.nonce]) &&
                (makerOrder.nonce >= userMinOrderNonce[makerOrder.signer]),
            "Order: Matching order expired"
        );

        // Verify the signer is not address(0)
        require(makerOrder.signer != address(0), "Order: Invalid signer");

        // Verify the amount is not 0
        require(makerOrder.amount > 0, "Order: Amount cannot be 0");

        // Verify the validity of the signature
        require(
            SignatureChecker.verify(
                orderHash,
                makerOrder.signer,
                makerOrder.v,
                makerOrder.r,
                makerOrder.s,
                DOMAIN_SEPARATOR
            ),
            "Signature: Invalid"
        );

        // Verify whether the currency is whitelisted
        require(currencyManager.isCurrencyWhitelisted(makerOrder.currency), "Currency: Not whitelisted");

        // Verify whether strategy can be executed
        require(executionManager.isStrategyWhitelisted(makerOrder.strategy), "Strategy: Not whitelisted");
    }
}

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

// OpenZeppelin contracts
import {Ownable} from "@openzeppelin/contracts/access/Ownable.sol";
import {ReentrancyGuard} from "@openzeppelin/contracts/security/ReentrancyGuard.sol";
import {IERC20, SafeERC20} from "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";

// LooksRare interfaces
import {ICurrencyManager} from "./interfaces/ICurrencyManager.sol";
import {IExecutionManager} from "./interfaces/IExecutionManager.sol";
import {IExecutionStrategy} from "./interfaces/IExecutionStrategy.sol";
import {IRoyaltyFeeManager} from "./interfaces/IRoyaltyFeeManager.sol";
import {ILooksRareExchange} from "./interfaces/ILooksRareExchange.sol";
import {ITransferManagerNFT} from "./interfaces/ITransferManagerNFT.sol";
import {ITransferSelectorNFT} from "./interfaces/ITransferSelectorNFT.sol";
import {IWETH} from "./interfaces/IWETH.sol";

// LooksRare libraries
import {OrderTypes} from "./libraries/OrderTypes.sol";
import {SignatureChecker} from "./libraries/SignatureChecker.sol";


contract LooksRareExchange is ILooksRareExchange, ReentrancyGuard, Ownable {
    using SafeERC20 for IERC20;
    //订单的卖家和买家信息
    using OrderTypes for OrderTypes.MakerOrder;
    using OrderTypes for OrderTypes.TakerOrder;
    //weth的地址
    address public immutable WETH;
    、、EIP712的信息
    bytes32 public immutable DOMAIN_SEPARATOR;
    //手续费地址
    address public protocolFeeRecipient;
    //looksrare的周边合约地址
    ICurrencyManager public currencyManager;
    IExecutionManager public executionManager;
    IRoyaltyFeeManager public royaltyFeeManager;
    ITransferSelectorNFT public transferSelectorNFT;
    //用于取消订单和校验订单是否合法的逻辑
    mapping(address => uint256) public userMinOrderNonce;
    mapping(address => mapping(uint256 => bool)) private _isUserOrderNonceExecutedOrCancelled;

    event CancelAllOrders(address indexed user, uint256 newMinNonce);
    event CancelMultipleOrders(address indexed user, uint256[] orderNonces);
    event NewCurrencyManager(address indexed currencyManager);
    event NewExecutionManager(address indexed executionManager);
    event NewProtocolFeeRecipient(address indexed protocolFeeRecipient);
    event NewRoyaltyFeeManager(address indexed royaltyFeeManager);
    event NewTransferSelectorNFT(address indexed transferSelectorNFT);

    event RoyaltyPayment(
        address indexed collection,
        uint256 indexed tokenId,
        address indexed royaltyRecipient,
        address currency,
        uint256 amount
    );

    event TakerAsk(
        bytes32 orderHash, // bid hash of the maker order
        uint256 orderNonce, // user order nonce
        address indexed taker, // sender address for the taker ask order
        address indexed maker, // maker address of the initial bid order
        address indexed strategy, // strategy that defines the execution
        address currency, // currency address
        address collection, // collection address
        uint256 tokenId, // tokenId transferred
        uint256 amount, // amount of tokens transferred
        uint256 price // final transacted price
    );

    event TakerBid(
        bytes32 orderHash, // ask hash of the maker order
        uint256 orderNonce, // user order nonce
        address indexed taker, // sender address for the taker bid order
        address indexed maker, // maker address of the initial ask order
        address indexed strategy, // strategy that defines the execution
        address currency, // currency address
        address collection, // collection address
        uint256 tokenId, // tokenId transferred
        uint256 amount, // amount of tokens transferred
        uint256 price // final transacted price
    );

    /**
     * @notice Constructor 保存好签名校验需要的参数，保存周边合约的地址
     * @param _currencyManager currency manager address
     * @param _executionManager execution manager address
     * @param _royaltyFeeManager royalty fee manager address
     * @param _WETH wrapped ether address (for other chains, use wrapped native asset)
     * @param _protocolFeeRecipient protocol fee recipient
     */
    constructor(
        address _currencyManager,
        address _executionManager,
        address _royaltyFeeManager,
        address _WETH,
        address _protocolFeeRecipient
    ) {
        // Calculate the domain separator
        DOMAIN_SEPARATOR = keccak256(
            abi.encode(
                0x8b73c3c69bb8fe3d512ecc4cf759cc79239f7b179b0ffacaa9a75d522b39400f, // keccak256("EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)")
                0xda9101ba92939daf4bb2e18cd5f942363b9297fbc3232c9dd964abb1fb70ed71, // keccak256("LooksRareExchange")
                0xc89efdaa54c0f20c7adf612882df0950f5a951637e0307cdcb4c672f298b8bc6, // keccak256(bytes("1")) for versionId = 1
                block.chainid,
                address(this)
            )
        );

        currencyManager = ICurrencyManager(_currencyManager);
        executionManager = IExecutionManager(_executionManager);
        royaltyFeeManager = IRoyaltyFeeManager(_royaltyFeeManager);
        WETH = _WETH;
        protocolFeeRecipient = _protocolFeeRecipient;
    }

    /**
     * @notice Cancel all pending orders for a sender
        取消所有订单
     * @param minNonce minimum user nonce
     */
    function cancelAllOrdersForSender(uint256 minNonce) external {
        require(minNonce > userMinOrderNonce[msg.sender], "Cancel: Order nonce lower than current");
        require(minNonce < userMinOrderNonce[msg.sender] + 500000, "Cancel: Cannot cancel more orders");
        userMinOrderNonce[msg.sender] = minNonce;

        emit CancelAllOrders(msg.sender, minNonce);
    }

    /**
     * @notice Cancel maker orders
      根据需要取消订单
     * @param orderNonces array of order nonces
     */
    function cancelMultipleMakerOrders(uint256[] calldata orderNonces) external {
        require(orderNonces.length > 0, "Cancel: Cannot be empty");

        for (uint256 i = 0; i < orderNonces.length; i++) {
            require(orderNonces[i] >= userMinOrderNonce[msg.sender], "Cancel: Order nonce lower than current");
            _isUserOrderNonceExecutedOrCancelled[msg.sender][orderNonces[i]] = true;
        }

        emit CancelMultipleOrders(msg.sender, orderNonces);
    }

    /**
     * @notice Match ask with a taker bid order using ETH
        核心exchange业务逻辑并且eth和weth混合支付，可能你的weth不足，不要紧，再用点eth，这里面会将eth换成weth，就不用你先去兑换了，节省gas
     * @param takerBid taker bid order
     * @param makerAsk maker ask order
     */
    function matchAskWithTakerBidUsingETHAndWETH(
        OrderTypes.TakerOrder calldata takerBid,
        OrderTypes.MakerOrder calldata makerAsk
    ) external payable override nonReentrant {
     //确定是卖家挂单才行，因为买家询价是不能用eth支付的
        require((makerAsk.isOrderAsk) && (!takerBid.isOrderAsk), "Order: Wrong sides");
        require(makerAsk.currency == WETH, "Order: Currency must be WETH");
        require(msg.sender == takerBid.taker, "Order: Taker must be the sender");
    //eth不足，先将weth转移给卖家
        // If not enough ETH to cover the price, use WETH
        if (takerBid.price > msg.value) {
            IERC20(WETH).safeTransferFrom(msg.sender, address(this), (takerBid.price - msg.value));
        } else {
            require(takerBid.price == msg.value, "Order: Msg.value too high");
        }
        //将eth兑换成weth来交易
        // Wrap ETH sent to this contract
        IWETH(WETH).deposit{value: msg.value}();
        //使用eip712校验订单
        // Check the maker ask order
        bytes32 askHash = makerAsk.hash();
        _validateOrder(makerAsk, askHash);
         //挂单，拍卖有不同的交易费费率，从这取出来
        // Retrieve execution parameters
        (bool isExecutionValid, uint256 tokenId, uint256 amount) = IExecutionStrategy(makerAsk.strategy)
            .canExecuteTakerBid(takerBid, makerAsk);

        require(isExecutionValid, "Strategy: Execution invalid");

        // Update maker ask order status to true (prevents replay)
        //先将订单置为已完成，防止重入
        _isUserOrderNonceExecutedOrCancelled[makerAsk.signer][makerAsk.nonce] = true;

        // Execution part 1/2
        //真正开始交易的地方，分两步，转移钱，再转移nft
        _transferFeesAndFundsWithWETH(
            makerAsk.strategy,
            makerAsk.collection,
            tokenId,
            makerAsk.signer,
            takerBid.price,
            makerAsk.minPercentageToAsk
        );

        // Execution part 2/2
        _transferNonFungibleToken(makerAsk.collection, makerAsk.signer, takerBid.taker, tokenId, amount);

        emit TakerBid(
            askHash,
            makerAsk.nonce,
            takerBid.taker,
            makerAsk.signer,
            makerAsk.strategy,
            makerAsk.currency,
            makerAsk.collection,
            tokenId,
            amount,
            takerBid.price
        );
    }

    /**
     * @notice Match a takerBid with a matchAsk
       基础撮合订单，和上面的区别就是这里只能用weth
     * @param takerBid taker bid order
     * @param makerAsk maker ask order
     */
    function matchAskWithTakerBid(OrderTypes.TakerOrder calldata takerBid, OrderTypes.MakerOrder calldata makerAsk)
        external
        override
        nonReentrant
    {
        require((makerAsk.isOrderAsk) && (!takerBid.isOrderAsk), "Order: Wrong sides");
        require(msg.sender == takerBid.taker, "Order: Taker must be the sender");

        // Check the maker ask order
        bytes32 askHash = makerAsk.hash();
        _validateOrder(makerAsk, askHash);

        (bool isExecutionValid, uint256 tokenId, uint256 amount) = IExecutionStrategy(makerAsk.strategy)
            .canExecuteTakerBid(takerBid, makerAsk);

        require(isExecutionValid, "Strategy: Execution invalid");

        // Update maker ask order status to true (prevents replay)
        _isUserOrderNonceExecutedOrCancelled[makerAsk.signer][makerAsk.nonce] = true;

        // Execution part 1/2
        _transferFeesAndFunds(
            makerAsk.strategy,
            makerAsk.collection,
            tokenId,
            makerAsk.currency,
            msg.sender,
            makerAsk.signer,
            takerBid.price,
            makerAsk.minPercentageToAsk
        );

        // Execution part 2/2
        _transferNonFungibleToken(makerAsk.collection, makerAsk.signer, takerBid.taker, tokenId, amount);

        emit TakerBid(
            askHash,
            makerAsk.nonce,
            takerBid.taker,
            makerAsk.signer,
            makerAsk.strategy,
            makerAsk.currency,
            makerAsk.collection,
            tokenId,
            amount,
            takerBid.price
        );
    }

    /**
     * @notice Match a takerAsk with a makerBid
        撮合订单，这里和上面一个的区别是这里是买家询价，上面是卖家挂单，这里的签名者是买家，上面的是卖家
     * @param takerAsk taker ask order
     * @param makerBid maker bid order
     */
    function matchBidWithTakerAsk(OrderTypes.TakerOrder calldata takerAsk, OrderTypes.MakerOrder calldata makerBid)
        external
        override
        nonReentrant
    {
        require((!makerBid.isOrderAsk) && (takerAsk.isOrderAsk), "Order: Wrong sides");
        require(msg.sender == takerAsk.taker, "Order: Taker must be the sender");

        // Check the maker bid order
        bytes32 bidHash = makerBid.hash();
        _validateOrder(makerBid, bidHash);

        (bool isExecutionValid, uint256 tokenId, uint256 amount) = IExecutionStrategy(makerBid.strategy)
            .canExecuteTakerAsk(takerAsk, makerBid);

        require(isExecutionValid, "Strategy: Execution invalid");

        // Update maker bid order status to true (prevents replay)
        _isUserOrderNonceExecutedOrCancelled[makerBid.signer][makerBid.nonce] = true;

        // Execution part 1/2
        _transferNonFungibleToken(makerBid.collection, msg.sender, makerBid.signer, tokenId, amount);

        // Execution part 2/2
        _transferFeesAndFunds(
            makerBid.strategy,
            makerBid.collection,
            tokenId,
            makerBid.currency,
            makerBid.signer,
            takerAsk.taker,
            takerAsk.price,
            takerAsk.minPercentageToAsk
        );

        emit TakerAsk(
            bidHash,
            makerBid.nonce,
            takerAsk.taker,
            makerBid.signer,
            makerBid.strategy,
            makerBid.currency,
            makerBid.collection,
            tokenId,
            amount,
            takerAsk.price
        );
    }
    //修改周边合约的地址，用于升级或者出bug用
    /**
     * @notice Update currency manager
     * @param _currencyManager new currency manager address
     */
    function updateCurrencyManager(address _currencyManager) external onlyOwner {
        require(_currencyManager != address(0), "Owner: Cannot be null address");
        currencyManager = ICurrencyManager(_currencyManager);
        emit NewCurrencyManager(_currencyManager);
    }

    /**
     * @notice Update execution manager
     * @param _executionManager new execution manager address
     */
    function updateExecutionManager(address _executionManager) external onlyOwner {
        require(_executionManager != address(0), "Owner: Cannot be null address");
        executionManager = IExecutionManager(_executionManager);
        emit NewExecutionManager(_executionManager);
    }

    /**
     * @notice Update protocol fee and recipient
     * @param _protocolFeeRecipient new recipient for protocol fees
     */
    function updateProtocolFeeRecipient(address _protocolFeeRecipient) external onlyOwner {
        protocolFeeRecipient = _protocolFeeRecipient;
        emit NewProtocolFeeRecipient(_protocolFeeRecipient);
    }

    /**
     * @notice Update royalty fee manager
     * @param _royaltyFeeManager new fee manager address
     */
    function updateRoyaltyFeeManager(address _royaltyFeeManager) external onlyOwner {
        require(_royaltyFeeManager != address(0), "Owner: Cannot be null address");
        royaltyFeeManager = IRoyaltyFeeManager(_royaltyFeeManager);
        emit NewRoyaltyFeeManager(_royaltyFeeManager);
    }

    /**
     * @notice Update transfer selector NFT
     * @param _transferSelectorNFT new transfer selector address
     */
    function updateTransferSelectorNFT(address _transferSelectorNFT) external onlyOwner {
        require(_transferSelectorNFT != address(0), "Owner: Cannot be null address");
        transferSelectorNFT = ITransferSelectorNFT(_transferSelectorNFT);

        emit NewTransferSelectorNFT(_transferSelectorNFT);
    }

    //订单是否取消
    /**
     * @notice Check whether user order nonce is executed or cancelled
     * @param user address of user
     * @param orderNonce nonce of the order
     */
    function isUserOrderNonceExecutedOrCancelled(address user, uint256 orderNonce) external view returns (bool) {
        return _isUserOrderNonceExecutedOrCancelled[user][orderNonce];
    }


    /**
       N个费用处理，转移钱，用传入的代币交易
     * @notice Transfer fees and funds to royalty recipient, protocol, and seller
     * @param strategy address of the execution strategy
     * @param collection non fungible token address for the transfer
     * @param tokenId tokenId
     * @param currency currency being used for the purchase (e.g., WETH/USDC)
     * @param from sender of the funds
     * @param to seller's recipient
     * @param amount amount being transferred (in currency)
     * @param minPercentageToAsk minimum percentage of the gross amount that goes to ask
     */
    function _transferFeesAndFunds(
        address strategy,
        address collection,
        uint256 tokenId,
        address currency,
        address from,
        address to,
        uint256 amount,
        uint256 minPercentageToAsk
    ) internal {
        // Initialize the final amount that is transferred to seller
        //最终的给卖家的钱，会经过一层又一层的吃拿卡要
        uint256 finalSellerAmount = amount;

        // 1. Protocol fee 官方手续费
        {
            uint256 protocolFeeAmount = _calculateProtocolFee(strategy, amount);

            // Check if the protocol fee is different than 0 for this strategy
            if ((protocolFeeRecipient != address(0)) && (protocolFeeAmount != 0)) {
                IERC20(currency).safeTransferFrom(from, protocolFeeRecipient, protocolFeeAmount);
                finalSellerAmount -= protocolFeeAmount;
            }
        }

        // 2. Royalty fee 版权费
        {
            (address royaltyFeeRecipient, uint256 royaltyFeeAmount) = royaltyFeeManager
                .calculateRoyaltyFeeAndGetRecipient(collection, tokenId, amount);

            // Check if there is a royalty fee and that it is different to 0
            if ((royaltyFeeRecipient != address(0)) && (royaltyFeeAmount != 0)) {
                IERC20(currency).safeTransferFrom(from, royaltyFeeRecipient, royaltyFeeAmount);
                finalSellerAmount -= royaltyFeeAmount;

                emit RoyaltyPayment(collection, tokenId, royaltyFeeRecipient, currency, royaltyFeeAmount);
            }
        }

        //保证给卖家的钱的最小值，要有人性，手动狗头
        require((finalSellerAmount * 10000) >= (minPercentageToAsk * amount), "Fees: Higher than expected");

        // 3. Transfer final amount (post-fees) to seller
        {
            IERC20(currency).safeTransferFrom(from, to, finalSellerAmount);
        }
    }

    /**
      和上面的类似，只是用了weth
     * @notice Transfer fees and funds to royalty recipient, protocol, and seller
     * @param strategy address of the execution strategy
     * @param collection non fungible token address for the transfer
     * @param tokenId tokenId
     * @param to seller's recipient
     * @param amount amount being transferred (in currency)
     * @param minPercentageToAsk minimum percentage of the gross amount that goes to ask
     */
    function _transferFeesAndFundsWithWETH(
        address strategy,
        address collection,
        uint256 tokenId,
        address to,
        uint256 amount,
        uint256 minPercentageToAsk
    ) internal {
        // Initialize the final amount that is transferred to seller
        uint256 finalSellerAmount = amount;

        // 1. Protocol fee
        {
            uint256 protocolFeeAmount = _calculateProtocolFee(strategy, amount);

            // Check if the protocol fee is different than 0 for this strategy
            if ((protocolFeeRecipient != address(0)) && (protocolFeeAmount != 0)) {
                IERC20(WETH).safeTransfer(protocolFeeRecipient, protocolFeeAmount);
                finalSellerAmount -= protocolFeeAmount;
            }
        }

        // 2. Royalty fee
        {
            (address royaltyFeeRecipient, uint256 royaltyFeeAmount) = royaltyFeeManager
                .calculateRoyaltyFeeAndGetRecipient(collection, tokenId, amount);

            // Check if there is a royalty fee and that it is different to 0
            if ((royaltyFeeRecipient != address(0)) && (royaltyFeeAmount != 0)) {
                IERC20(WETH).safeTransfer(royaltyFeeRecipient, royaltyFeeAmount);
                finalSellerAmount -= royaltyFeeAmount;

                emit RoyaltyPayment(collection, tokenId, royaltyFeeRecipient, address(WETH), royaltyFeeAmount);
            }
        }

        require((finalSellerAmount * 10000) >= (minPercentageToAsk * amount), "Fees: Higher than expected");

        // 3. Transfer final amount (post-fees) to seller
        {
            IERC20(WETH).safeTransfer(to, finalSellerAmount);
        }
    }

    /**
     * @notice Transfer NFT
        那到官方规定的NFT转移合约，转移NFT
     * @param collection address of the token collection
     * @param from address of the sender
     * @param to address of the recipient
     * @param tokenId tokenId
     * @param amount amount of tokens (1 for ERC721, 1+ for ERC1155)
     * @dev For ERC721, amount is not used
     */
    function _transferNonFungibleToken(
        address collection,
        address from,
        address to,
        uint256 tokenId,
        uint256 amount
    ) internal {
        // Retrieve the transfer manager address
        address transferManager = transferSelectorNFT.checkTransferManagerForToken(collection);

        // If no transfer manager found, it returns address(0)
        require(transferManager != address(0), "Transfer: No NFT transfer manager available");

        // If one is found, transfer the token
        ITransferManagerNFT(transferManager).transferNonFungibleToken(collection, from, to, tokenId, amount);
    }

    /**
     * @notice Calculate protocol fee for an execution strategy
     * @param executionStrategy strategy
     * @param amount amount to transfer
     */
    function _calculateProtocolFee(address executionStrategy, uint256 amount) internal view returns (uint256) {
        uint256 protocolFee = IExecutionStrategy(executionStrategy).viewProtocolFee();
        return (protocolFee * amount) / 10000;
    }

    /**
        校验订单
     * @notice Verify the validity of the maker order
     * @param makerOrder maker order
     * @param orderHash computed hash for the order
     */
    function _validateOrder(OrderTypes.MakerOrder calldata makerOrder, bytes32 orderHash) internal view {
        // Verify whether order nonce has expired
        require(
  //订单是否取消，并且订单的nonce>合约记录的订单签名者的nonce值，因为可能其他人恶意取消订单，这里取签名者保证别人恶意取消没用       (!_isUserOrderNonceExecutedOrCancelled[makerOrder.signer][makerOrder.nonce]) &&
                (makerOrder.nonce >= userMinOrderNonce[makerOrder.signer]),
            "Order: Matching order expired"
        );

        // Verify the signer is not address(0)
        require(makerOrder.signer != address(0), "Order: Invalid signer");

        // Verify the amount is not 0
        require(makerOrder.amount > 0, "Order: Amount cannot be 0");

        // Verify the validity of the signature
        require(
            SignatureChecker.verify(
                orderHash,
                makerOrder.signer,
                makerOrder.v,
                makerOrder.r,
                makerOrder.s,
                DOMAIN_SEPARATOR
            ),
            "Signature: Invalid"
        );

        // Verify whether the currency is whitelisted
        require(currencyManager.isCurrencyWhitelisted(makerOrder.currency), "Currency: Not whitelisted");

        // Verify whether strategy can be executed
        require(executionManager.isStrategyWhitelisted(makerOrder.strategy), "Strategy: Not whitelisted");
    }
}