Auction.sol

pragma solidity ^0.4.19;

contract Auction {
    uint ask;
    uint startTime;
    uint timeLimit;
    address owner;
    bool completed;
    
    uint winningBid;
    address winningBidder;
    
    function Auction(uint _ask, uint _timeLimit) public {
        owner = msg.sender;
        ask = _ask;
        startTime = now;
        timeLimit = _timeLimit;
    }
    
    function isActive() view public returns (bool) {
        return timeLimit == 0 || now < (startTime + timeLimit);
    }
    
    function bid() payable public {
        require(isActive());
        require(ask <= msg.value);
        require(winningBid < msg.value);
        
        if (winningBidder > 0) {
            // Return winningBidder funds
            uint x = winningBid;
            winningBid = 0;
            winningBidder.transfer(x);
        }
        
        // Set new winning bid
        winningBid = msg.value;
        winningBidder = msg.sender;
    }
    
    function getAsk() public view returns (uint) {
        return ask;
    }
    
    function getWinningBid() public view returns (uint) {
        return winningBid;
    }
    
    function payOwner() public {
        require(!isActive());
        require(!completed);
        require(msg.sender == winningBidder);
        completed = true;
        
        if (!owner.send(winningBid)) revert();
        
    }
    
}