Jedi Ethereum Betting Smart Contract

Bet.sol

pragma solidity ^0.4.8;
  contract Bet {

    //jedi bet status
    uint constant STATUS_WIN = 1;
    uint constant STATUS_LOSE = 2;
    uint constant STATUS_TIE = 3;
    uint constant STATUS_PENDING = 4;

    //game status
    uint constant STATUS_NOT_STARTED = 1;
    uint constant STATUS_STARTED = 2;
    uint constant STATUS_COMPLETE = 3;

    //general status
    uint constant STATUS_ERROR = 4;

    //the 'better' structure
    struct JediBet {
      uint guess;
      address addr;
      uint status;
    }

    //the 'game' structure
    struct Game {
      uint256 betAmount;
      uint outcome;
      uint status;
      JediBet originator;
      JediBet taker;
    }

    //the game
    Game game;

    //fallback function
    function() public payable {}

    function createBet(uint _guess) public payable {
      game = Game(msg.value, 0, STATUS_STARTED, JediBet(_guess, msg.sender, STATUS_PENDING), JediBet(0, 0, STATUS_NOT_STARTED));
      game.originator = JediBet(_guess, msg.sender, STATUS_PENDING);
    }

    function takeBet(uint _guess) public payable { 
      //requires the taker to make the same bet amount     
      require(msg.value == game.betAmount);
      game.taker = JediBet(_guess, msg.sender, STATUS_PENDING);
      generateBetOutcome();
    }

    function payout() public payable {

      checkPermissions(msg.sender);
     
     if (game.originator.status == STATUS_TIE && game.taker.status == STATUS_TIE) {
       game.originator.addr.transfer(game.betAmount);
       game.taker.addr.transfer(game.betAmount);
     } else {
        if (game.originator.status == STATUS_WIN) {
          game.originator.addr.transfer(game.betAmount*2);
        } else if (game.taker.status == STATUS_WIN) {
          game.taker.addr.transfer(game.betAmount*2);
        } else {
          game.originator.addr.transfer(game.betAmount);
          game.taker.addr.transfer(game.betAmount);
        }
     }
   }

    function checkPermissions(address sender) view private {
     //only the originator or taker can call this function
     require(sender == game.originator.addr || sender == game.taker.addr);  
    }

    function getBetAmount() public view returns (uint) {
      checkPermissions(msg.sender);
      return game.betAmount;
    }

     function getOriginatorGuess() public view returns (uint) {
       checkPermissions(msg.sender);
       return game.originator.guess;
     }

     function getTakerGuess() public view returns (uint) {
       checkPermissions(msg.sender);
       return game.taker.guess;
     }

     function getPot() public view returns (uint256) {
        checkPermissions(msg.sender);
        return this.balance;
     }

    function generateBetOutcome() private {
        //todo - not a great way to generate a random number but ok for now
        game.outcome = uint(block.blockhash(block.number-1))%10 + 1;
        game.status = STATUS_COMPLETE;

        if (game.originator.guess == game.taker.guess) {
          game.originator.status = STATUS_TIE;
          game.taker.status = STATUS_TIE;
        } else if (game.originator.guess > game.outcome && game.taker.guess > game.outcome) {
          game.originator.status = STATUS_TIE;
          game.taker.status = STATUS_TIE;
        } else {
           if ((game.outcome - game.originator.guess) < (game.outcome - game.taker.guess)) {
             game.originator.status = STATUS_WIN;
             game.taker.status = STATUS_LOSE;
           } else if ((game.outcome - game.taker.guess) < (game.outcome - game.originator.guess)) {
             game.originator.status = STATUS_LOSE;
             game.taker.status = STATUS_WIN;
           } else {
             game.originator.status = STATUS_ERROR;
             game.taker.status = STATUS_ERROR;
             game.status = STATUS_ERROR;
           }
        }
    }

     //returns - [<description>, 'originator', <originator status>, 'taker', <taker status>]
     function getBetOutcome() public view returns
     (string description, string originatorKey, uint originatorStatus, string takerKey, uint takerStatus) 
     {
        if (game.originator.status == STATUS_TIE || game.taker.status == STATUS_TIE) {
          description = "Both bets were the same or were over the number, the pot will be split";
        } else {
            if (game.originator.status == STATUS_WIN) {
             description = "Bet originator guess was closer to the number and will receive the pot";
           } else if (game.taker.status == STATUS_WIN) {
             description = "Bet taker guess was closer to the number and will receive the pot";
           } else {
             description = "Unknown Bet Outcome";
           }
        }
        originatorKey = "originator";
        originatorStatus = game.originator.status;
        takerKey = "taker";
        takerStatus = game.taker.status;
     }
  }