NFT 경매

NFT 관련 글이 길어 경매 파트는 따로 정리

 

event Start();
    event Bid(address indexed sender, uint amount);
    event Withdraw(address indexed bidder, uint amount);
    event End(address winner, uint amount);
    event Endedat(uint a);
    

    struct Auction {
            bool started;
            address owner;
            uint nftId;
            bool status;
            uint endAt;
            address highestBidder;
            uint highestBid;
            bool ended;
            
        }
    mapping(uint => Auction) auction;
    mapping(uint => mapping(address => uint)) public bids;
    
    function startAuction(uint nftId, address owner, uint _startingBid) public {
         auction[nftId].nftId = nftId;
         auction[nftId].owner = owner;
         auction[nftId].started = true;
         auction[nftId].highestBid = _startingBid;
         transferFrom(owner, address(this), nftId);
         auction[nftId].endAt = block.timestamp + 1 days;

         emit Endedat(auction[nftId].endAt);
      }

    function bid(uint nftId, address buyer, uint amount) public {
        require(auction[nftId].started, "not started");
        require(block.timestamp < auction[nftId].endAt, "ended");
        require(amount > auction[nftId].highestBid, "value < highest");

        if (auction[nftId].highestBidder != address(0)) {
            bids[nftId][auction[nftId].highestBidder] += auction[nftId].highestBid;

        }
        token.transferFrom(buyer, address(this), amount);
        auction[nftId].highestBidder = buyer;
        auction[nftId].highestBid = amount;

    }

    function withdraw(address addr, uint nftId) public {
        uint bal = bids[nftId][addr];
        bids[nftId][addr] = 0;
        token.transferFrom(address(this), addr , bal);
        emit Withdraw(addr, bal);
    }

    function end(uint nftId) public {
        require(auction[nftId].started, "not started");
        require(block.timestamp >= auction[nftId].endAt, "not ended");
        require(!auction[nftId].ended, "ended");

        auction[nftId].ended = true;
        if (auction[nftId].highestBidder != address(0)) {
            safeTransferFrom(address(this), auction[nftId].highestBidder, nftId);
            token.transferFrom(address(this), auction[nftId].owner, auction[nftId].highestBid);
        } else {
            safeTransferFrom(address(this), auction[nftId].owner, nftId);
        }
        emit End(auction[nftId].highestBidder, auction[nftId].highestBid);
    }

---

event 와 Auction 구조체 설정

 

mapping(uint => Auction) auction;

auction[uint] = Auction;

mapping(uint => mapping(address => uint)) public bids;

bids[uint][address] = uint;

uint 배열에 해당하는 address 값이 가르키는 uint => bids

---

function startAuction

function startAuction(uint nftId, address owner, uint _startingBid) public {

auction[nftId].nftId = nftId;

auction[nftId].owner = owner;

auction[nftId].started = true;

auction[nftId].highestBid = _startingBid;

transferFrom(owner, address(this), nftId);

• nft의 소유주가 auction을 진행하기 위해서 nft 컨트렉트에게 nft를 먼저 전달한다.

auction[nftId].endAt = block.timestamp + 1 days;

• 경매 기간 설정 : +1days; 부분
• block.timestamp 보안 설정 필요

emit Endedat(auction[nftId].endAt);

}

---

function bid

• 입찰 함수

function bid(uint nftId, address buyer, uint amount) public {

require(auction[nftId].started, "not started");

require(block.timestamp < auction[nftId].endAt, "ended");

require(amount > auction[nftId].highestBid, "value < highest");

if (auction[nftId].highestBidder != address(0)) {

bids[nftId][auction[nftId].highestBidder] += auction[nftId].highestBid;

• 해당 nftId에 action[nftId].highestBidder가 제시한 bids 값에 갱신된 highestBid를 더해준다

}

token.transferFrom(buyer, address(this), amount);

• ERC-20 transferForm을 이용해 입찰금 amount를 nft 컨트렉트로 전송시켜주고

auction[nftId].highestBidder = buyer;

auction[nftId].highestBid = amount;

• 갱신

}

---

function withdraw

• 최고 입찰자가 아닌 유저는 입찰금 회수 기능 제공

function withdraw(address addr, uint nftId) public {

uint bal = bids[nftId][addr];

• 해당 nftId에 회수를 실행한 유저의 bids를 빼기 위해서 먼저 bal로 저장해주고

bids[nftId][addr] = 0;

• bids를 초기화 시켜줌

token.transferFrom(address(this), addr , bal);

• transferForm으로 저장시킨 bal 값을 전송

emit Withdraw(addr, bal);

• event로 기록

}

---

function end

• 입찰 종료 실행 함수 : 판매자만 호출 가능

function end(uint nftId) public {

require(auction[nftId].started, "not started");

require(block.timestamp >= auction[nftId].endAt, "not ended");

require(!auction[nftId].ended, "ended");

• require 문으로 걸리는것들 거르고

auction[nftId].ended = true;

if (auction[nftId].highestBidder != address(0)) {

safeTransferFrom(address(this), auction[nftId].highestBidder, nftId);

• nft 컨트렉트가 최고 입찰자에게 입찰에 해당하는 nftId 값을 추적해서 전달

token.transferFrom(address(this), auction[nftId].owner, auction[nftId].highestBid);

• nft 컨트렉트가 경매를 시작한 판매자에게 최고 입찰금을 전달

} else {

safeTransferFrom(address(this), auction[nftId].owner, nftId);

}

emit End(auction[nftId].highestBidder, auction[nftId].highestBid);

• End 이벤트로 기록

}

---