Lottery

contract Lottery {
    uint startBlock;
    uint numParticipants;
    address[] participants;
    uint64[] secrets;
    mapping (address => bytes32) hashes;
    mapping (address => uint) amounts;

    function Lottery() { startBlock = block.number; }

    function submitSecret(uint64 secret) {
        if (!(block.number % 88 < 0x44 && block.number % 88 >= 0x30)) return;
        if (sha3(bytes8(secret)) != hashes[msg.sender]) return;
        participants.length++;
        participants[participants.length - 1] = msg.sender;
        secrets.length++;
        secrets[secrets.length - 1] = secret;
    }

    function random() returns (uint64 r) {
        for (uint i = 0; i < secrets.length; i++) {
            r ^= secrets[i];
        }
    }

    function payout() {
        if (!payoutReady()) return;
        uint winner = random() % participants.length;
        participants[winner].call.value(this.balance - tx.gasprice * 25000)();
        startBlock = block.number;
        participants.length = 0;
        secrets.length = 0;
        numParticipants = 0;
    }

    function payoutReady() returns (bool) {
        return block.number % 88 > 0x44 && block.number - startBlock > 0x44;
    }

    function buyTicket(bytes32 hash) {
        if (block.number % 88 >= 0x28) return;
        hashes[msg.sender] = hash;
        amounts[msg.sender] += msg.value;
        numParticipants++;
    }
}