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contracts...25_BlindAuction.sol

pragma solidity >=0.7.0 <0.9.0;

contract BlindAuction {

    // Variables

    struct Bid {
        bytes32 blindedBid;
        uint depositAmount;
    }

    address payable public beneficiary;
    uint public biddingEnd;
    uint public revealTime;
    bool  public ended;

    mapping(address => Bid[]) public bids;

    address public highestBidder;
    uint public highestBid;

    mapping(address => uint) pendingReturns;

    // Events
    
    event AuctionEnded(address winner, uint highestBid);

    // Modifiers

    modifier onlyBefore(uint _time) {
        require(block.timestamp < _time);
        _;
    }

    modifier onlyAfter(uint _time) {
        require(block.timestamp > _time);
        _;
    }

    // Functions

    constructor(address payable _beneficiary, uint _biddingEnd, uint _revealTime) {
        beneficiary = _beneficiary;
        biddingEnd = block.timestamp + _biddingEnd;
        revealTime = biddingEnd + _revealTime;
    }

    function generateBlindedBidBytes32(uint _value, bool fake) public pure returns(bytes32) {
      return keccak256(abi.encodePacked(_value, fake));
    }

    function bid(bytes32 _blindedBid) public payable onlyBefore(biddingEnd) {
      bids[msg.sender].push(Bid({ blindedBid: _blindedBid, depositAmount: msg.value }));
    }


    function placeBid(address _bidder, uint _value) internal returns(bool success)  {
      if (_value <= highestBid) {
          return false;
      }
       if (highestBidder != address(0)) {
          pendingReturns[highestBidder] += highestBid;
      }
      highestBidder = _bidder;
      highestBid = _value;
      return true;
    }

    function reveal(uint[] memory _values, bool[] memory _fake) public onlyAfter(biddingEnd) onlyBefore(revealTime) {
      uint length = bids[msg.sender].length;
      require (_values.length == length);
      require (_fake.length == length);

      for(uint i=0; i<length; i++) {
          Bid storage bidToCheck = bids[msg.sender][i];
          (uint value, bool fake) = (_values[i], _fake[i]);
          if(bidToCheck.blindedBid != keccak256(abi.encodePacked(value, fake))) {
              continue;
          }
          if(!fake && bidToCheck.depositAmount >= value) {
              if(!placeBid(msg.sender, value)) {
                payable(msg.sender).transfer(bidToCheck.depositAmount * (1 ether));
              }
          }
          bidToCheck.blindedBid = bytes32(0);
      }
    }


    function withdraw() public {
      uint amount = pendingReturns[msg.sender];
      if (amount > 0) {
          pendingReturns[msg.sender] = 0;
          payable(msg.sender).transfer(amount);
      }
    }
    
    function auctionEnd() public payable onlyAfter(revealTime) {
      require(!ended);
      emit AuctionEnded(highestBidder, highestBid);
      ended = true;
      beneficiary.transfer(highestBid);

    }    

}