yesnovoting.sol

contract SimpleYesNoVotingContract {

    event voteStarted();
    event voted(address voter);
    event voteEnded(uint yesVotes, uint noVotes)

    address public officialAddress;

    enum State { Created, Voting, Ended }
    State public state;

    modifier inState(State _state) {
        require(state == _state);
        _;
    }

    modifier onlyOfficial() {
        require(msg.sender == officialAddress);
        _;
    }

    modifier notAlreadyVoted() {
        require(!voteRegister(msg.sender));
        _;
    }

    constructor() public {
        officialAddress = msg.sender;
        state = State.Created;
    }
    
    mapping(address => bool) public voteRegister;
    uint public yesVotes = 0;
    uint public noVotes = 0;

    function startVote()
        public
        inState(State.Created)
        onlyOfficial
    {
        state = State.Voting;
        emit voteStarted();
    }


    function vote(bool yes)
        public
        inState(State.Voting)
        notAlreadyVoted
        returns (bool voted)
    {
        if (yes){
            yesVotes++;
        } else {
            noVotes++;
        }
        voteRegister[msg.sender] = true;
        emit voted(msg.sender);
    }

    function endVote()
        public
        inState(State.Voting)
        onlyOfficial
    {
        state = State.Ended;
        emit voteEnded(yesVotes, noVotes);
    }
}