// Vulnerability label: time manipulation
// solium-disable linebreak-style
pragma solidity ^0.4.24;

contract AceDice {
  /// *** Constants section
  
  // Each bet is deducted 1% in favour of the house, but no less than some minimum.
  // The lower bound is dictated by gas costs of the settleBet transaction, providing
  // headroom for up to 10 Gwei prices.
  uint constant HOUSE_EDGE_PERCENT = 1;
  uint constant HOUSE_EDGE_MINIMUM_AMOUNT = 0.0004 ether;
  
  // Bets lower than this amount do not participate in jackpot rolls (and are
  // not deducted JACKPOT_FEE).
  uint constant MIN_JACKPOT_BET = 0.1 ether;
  
  // Chance to win jackpot (currently 0.1%) and fee deducted into jackpot fund.
  uint constant JACKPOT_MODULO = 1000;
  uint constant JACKPOT_FEE = 0.001 ether;
  
  // There is minimum and maximum bets.
  uint constant MIN_BET = 0.01 ether;
  uint constant MAX_AMOUNT = 300000 ether;
  
  // Modulo is a number of equiprobable outcomes in a game:
  // - 2 for coin flip
  // - 6 for dice
  // - 6*6 = 36 for double dice
  // - 100 for etheroll
  // - 37 for roulette
  // etc.
  // It's called so because 256-bit entropy is treated like a huge integer and
  // the remainder of its division by modulo is considered bet outcome.
  // uint constant MAX_MODULO = 100;
  
  // For modulos below this threshold rolls are checked against a bit mask,
  // thus allowing betting on any combination of outcomes. For example, given
  // modulo 6 for dice, 101000 mask (base-2, big endian) means betting on
  // 4 and 6; for games with modulos higher than threshold (Etheroll), a simple
  // limit is used, allowing betting on any outcome in [0, N) range.
  //
  // The specific value is dictated by the fact that 256-bit intermediate
  // multiplication result allows implementing population count efficiently
  // for numbers that are up to 42 bits, and 40 is the highest multiple of
  // eight below 42.
  uint constant MAX_MASK_MODULO = 40;
  
  // This is a check on bet mask overflow.
  uint constant MAX_BET_MASK = 2 ** MAX_MASK_MODULO;
  
  // EVM BLOCKHASH opcode can query no further than 256 blocks into the
  // past. Given that settleBet uses block hash of placeBet as one of
  // complementary entropy sources, we cannot process bets older than this
  // threshold. On rare occasions AceDice croupier may fail to invoke
  // settleBet in this timespan due to technical issues or extreme Ethereum
  // congestion; such bets can be refunded via invoking refundBet.
  uint constant BET_EXPIRATION_BLOCKS = 250;
  
  // Some deliberately invalid address to initialize the secret signer with.
  // Forces maintainers to invoke setSecretSigner before processing any bets.
  address constant DUMMY_ADDRESS = 0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE;
  
  // Standard contract ownership transfer.
  address public owner;
  address private nextOwner;
  
  // Adjustable max bet profit. Used to cap bets against dynamic odds.
  uint public maxProfit;
  
  // The address corresponding to a private key used to sign placeBet commits.
  address public secretSigner;
  
  // Accumulated jackpot fund.
  uint128 public jackpotSize;
  
  uint public todaysRewardSize;

  // Funds that are locked in potentially winning bets. Prevents contract from
  // committing to bets it cannot pay out.
  uint128 public lockedInBets;
  
  // A structure representing a single bet.
  struct Bet {
    // Wager amount in wei.
    uint amount;
    // Modulo of a game.
    // uint8 modulo;
    // Number of winning outcomes, used to compute winning payment (* modulo/rollUnder),
    // and used instead of mask for games with modulo > MAX_MASK_MODULO.
    uint8 rollUnder;
    // Block number of placeBet tx.
    uint40 placeBlockNumber;
    // Bit mask representing winning bet outcomes (see MAX_MASK_MODULO comment).
    uint40 mask;
    // Address of a gambler, used to pay out winning bets.
    address gambler;
    // Address of inviter
    address inviter;
  }

  struct Profile{
    // picture index of profile avatar
    uint avatarIndex;
    // nickname of user
    string nickName;
  }
  
  // Mapping from commits to all currently active & processed bets.
  mapping (uint => Bet) bets;
  // Mapping for accumuldated bet amount and users
  mapping (address => uint) accuBetAmount;

  mapping (address => Profile) profiles;
  
  // Croupier account.
  address public croupier;
  
  // Events that are issued to make statistic recovery easier.
  event FailedPayment(address indexed beneficiary, uint amount);
  event Payment(address indexed beneficiary, uint amount, uint dice, uint rollUnder, uint betAmount);
  event JackpotPayment(address indexed beneficiary, uint amount, uint dice, uint rollUnder, uint betAmount);
  event VIPPayback(address indexed beneficiary, uint amount);
  
  // This event is emitted in placeBet to record commit in the logs.
  event Commit(uint commit);

  // 오늘의 랭킹 보상 지급 이벤트
  event TodaysRankingPayment(address indexed beneficiary, uint amount);
  
  // Constructor. Deliberately does not take any parameters.
  constructor () public {
    owner = msg.sender;
    secretSigner = DUMMY_ADDRESS;
    croupier = DUMMY_ADDRESS;
  }
  
  // Standard modifier on methods invokable only by contract owner.
  modifier onlyOwner {
    require (msg.sender == owner, "OnlyOwner methods called by non-owner.");
    _;
  }
  
  // Standard modifier on methods invokable only by contract owner.
  modifier onlyCroupier {
    require (msg.sender == croupier, "OnlyCroupier methods called by non-croupier.");
    _;
  }
  
  // Standard contract ownership transfer implementation,
  function approveNextOwner(address _nextOwner) external onlyOwner {
    require (_nextOwner != owner, "Cannot approve current owner.");
    nextOwner = _nextOwner;
  }
  
  function acceptNextOwner() external {
    require (msg.sender == nextOwner, "Can only accept preapproved new owner.");
    owner = nextOwner;
  }
  
  // Fallback function deliberately left empty. It's primary use case
  // is to top up the bank roll.
  function () public payable {
  }
  
  // See comment for "secretSigner" variable.
  function setSecretSigner(address newSecretSigner) external onlyOwner {
    secretSigner = newSecretSigner;
  }
  
  function getSecretSigner() external onlyOwner view returns(address){
    return secretSigner;
  }
  
  // Change the croupier address.
  function setCroupier(address newCroupier) external onlyOwner {
    croupier = newCroupier;
  }
  
  // Change max bet reward. Setting this to zero effectively disables betting.
  function setMaxProfit(uint _maxProfit) public onlyOwner {
    require (_maxProfit < MAX_AMOUNT, "maxProfit should be a sane number.");
    maxProfit = _maxProfit;
  }
  
  // This function is used to bump up the jackpot fund. Cannot be used to lower it.
  function increaseJackpot(uint increaseAmount) external onlyOwner {
    require (increaseAmount <= address(this).balance, "Increase amount larger than balance.");
    require (jackpotSize + lockedInBets + increaseAmount <= address(this).balance, "Not enough funds.");
    jackpotSize += uint128(increaseAmount);
  }
  
  // Funds withdrawal to cover costs of AceDice operation.
  function withdrawFunds(address beneficiary, uint withdrawAmount) external onlyOwner {
    require (withdrawAmount <= address(this).balance, "Increase amount larger than balance.");
    require (jackpotSize + lockedInBets + withdrawAmount <= address(this).balance, "Not enough funds.");
    sendFunds(beneficiary, withdrawAmount, withdrawAmount, 0, 0, 0);
  }
  
  // Contract may be destroyed only when there are no ongoing bets,
  // either settled or refunded. All funds are transferred to contract owner.
  function kill() external onlyOwner {
    require (lockedInBets == 0, "All bets should be processed (settled or refunded) before self-destruct.");
    selfdestruct(owner);
  }
  
  function encodePacketCommit(uint commitLastBlock, uint commit) private pure returns(bytes memory){
    return abi.encodePacked(uint40(commitLastBlock), commit);
  }
  
  function verifyCommit(uint commitLastBlock, uint commit, uint8 v, bytes32 r, bytes32 s) private view {
    // Check that commit is valid - it has not expired and its signature is valid.
    require (block.number <= commitLastBlock, "Commit has expired.");
    //bytes32 signatureHash = keccak256(abi.encodePacked(commitLastBlock, commit));
    bytes memory prefix = "\x19Ethereum Signed Message:\n32";
    bytes memory message = encodePacketCommit(commitLastBlock, commit);
    bytes32 messageHash = keccak256(abi.encodePacked(prefix, keccak256(message)));
    require (secretSigner == ecrecover(messageHash, v, r, s), "ECDSA signature is not valid.");
  }
  
  /// *** Betting logic
  
  // Bet states:
  // amount == 0 && gambler == 0 - 'clean' (can place a bet)
  // amount != 0 && gambler != 0 - 'active' (can be settled or refunded)
  // amount == 0 && gambler != 0 - 'processed' (can clean storage)
  //
  // NOTE: Storage cleaning is not implemented in this contract version; it will be added
  // with the next upgrade to prevent polluting Ethereum state with expired bets.
  
  // Bet placing transaction - issued by the player.
  // betMask - bet outcomes bit mask for modulo <= MAX_MASK_MODULO,
  // [0, betMask) for larger modulos.
  // modulo - game modulo.
  // commitLastBlock - number of the maximum block where "commit" is still considered valid.
  // commit - Keccak256 hash of some secret "reveal" random number, to be supplied
  // by the AceDice croupier bot in the settleBet transaction. Supplying
  // "commit" ensures that "reveal" cannot be changed behind the scenes
  // after placeBet have been mined.
  // r, s - components of ECDSA signature of (commitLastBlock, commit). v is
  // guaranteed to always equal 27.
  //
  // Commit, being essentially random 256-bit number, is used as a unique bet identifier in
  // the 'bets' mapping.
  //
  // Commits are signed with a block limit to ensure that they are used at most once - otherwise
  // it would be possible for a miner to place a bet with a known commit/reveal pair and tamper
  // with the blockhash. Croupier guarantees that commitLastBlock will always be not greater than
  // placeBet block number plus BET_EXPIRATION_BLOCKS. See whitepaper for details.
  function placeBet(uint betMask, uint commitLastBlock, uint commit, uint8 v, bytes32 r, bytes32 s) external payable {
    // Check that the bet is in 'clean' state.
    Bet storage bet = bets[commit];
    require (bet.gambler == address(0), "Bet should be in a 'clean' state.");
    
    // Validate input data ranges.
    uint amount = msg.value;
    //require (modulo > 1 && modulo <= MAX_MODULO, "Modulo should be within range.");
    require (amount >= MIN_BET && amount <= MAX_AMOUNT, "Amount should be within range.");
    require (betMask > 0 && betMask < MAX_BET_MASK, "Mask should be within range.");
    
    verifyCommit(commitLastBlock, commit, v, r, s);
    
    // uint rollUnder;
    uint mask;
    
    // if (modulo <= MAX_MASK_MODULO) {
    //   // Small modulo games specify bet outcomes via bit mask.
    //   // rollUnder is a number of 1 bits in this mask (population count).
    //   // This magic looking formula is an efficient way to compute population
    //   // count on EVM for numbers below 2**40. For detailed proof consult
    //   // the AceDice whitepaper.
    //   rollUnder = ((betMask * POPCNT_MULT) & POPCNT_MASK) % POPCNT_MODULO;
    //   mask = betMask;
    //   } else {
        // Larger modulos specify the right edge of half-open interval of
        // winning bet outcomes.
        require (betMask > 0 && betMask <= 100, "High modulo range, betMask larger than modulo.");
        // rollUnder = betMask;
      // }
      
      // Winning amount and jackpot increase.
      uint possibleWinAmount;
      uint jackpotFee;
      
      (possibleWinAmount, jackpotFee) = getDiceWinAmount(amount, betMask);
      
      // Enforce max profit limit.
      require (possibleWinAmount <= amount + maxProfit, "maxProfit limit violation. ");
      
      // Lock funds.
      lockedInBets += uint128(possibleWinAmount);
      jackpotSize += uint128(jackpotFee);
      
      // Check whether contract has enough funds to process this bet.
      require (jackpotSize + lockedInBets <= address(this).balance, "Cannot afford to lose this bet.");
      
      // Record commit in logs.
      emit Commit(commit);

      // Store bet parameters on blockchain.
      bet.amount = amount;
      // bet.modulo = uint8(modulo);
      bet.rollUnder = uint8(betMask);
      bet.placeBlockNumber = uint40(block.number);
      bet.mask = uint40(mask);
      bet.gambler = msg.sender;
      
      uint accuAmount = accuBetAmount[msg.sender];
      accuAmount = accuAmount + amount;
      accuBetAmount[msg.sender] = accuAmount;
    }

    function applyVIPLevel(address gambler, uint amount) private {
      uint accuAmount = accuBetAmount[gambler];
      uint rate;
      if(accuAmount >= 30 ether && accuAmount < 150 ether){
        rate = 1;
      } else if(accuAmount >= 150 ether && accuAmount < 300 ether){
        rate = 2;
      } else if(accuAmount >= 300 ether && accuAmount < 1500 ether){
        rate = 4;
      } else if(accuAmount >= 1500 ether && accuAmount < 3000 ether){
        rate = 6;
      } else if(accuAmount >= 3000 ether && accuAmount < 15000 ether){
        rate = 8;
      } else if(accuAmount >= 15000 ether && accuAmount < 30000 ether){
        rate = 10;
      } else if(accuAmount >= 30000 ether && accuAmount < 150000 ether){
        rate = 12;
      } else if(accuAmount >= 150000 ether){
        rate = 15;
      } else{
        return;
      }

      uint vipPayback = amount * rate / 10000;
      if(gambler.send(vipPayback)){
        emit VIPPayback(gambler, vipPayback);
      }
    }

    function placeBetWithInviter(uint betMask, uint commitLastBlock, uint commit, uint8 v, bytes32 r, bytes32 s, address inviter) external payable {
      // Check that the bet is in 'clean' state.
      Bet storage bet = bets[commit];
      require (bet.gambler == address(0), "Bet should be in a 'clean' state.");
      
      // Validate input data ranges.
      uint amount = msg.value;
      // require (modulo > 1 && modulo <= MAX_MODULO, "Modulo should be within range.");
      require (amount >= MIN_BET && amount <= MAX_AMOUNT, "Amount should be within range.");
      require (betMask > 0 && betMask < MAX_BET_MASK, "Mask should be within range.");
      require (address(this) != inviter && inviter != address(0), "cannot invite mysql");
      
      verifyCommit(commitLastBlock, commit, v, r, s);
      
      // uint rollUnder;
      uint mask;
      
      // if (modulo <= MAX_MASK_MODULO) {
      //   // Small modulo games specify bet outcomes via bit mask.
      //   // rollUnder is a number of 1 bits in this mask (population count).
      //   // This magic looking formula is an efficient way to compute population
      //   // count on EVM for numbers below 2**40. For detailed proof consult
      //   // the AceDice whitepaper.
      //   rollUnder = ((betMask * POPCNT_MULT) & POPCNT_MASK) % POPCNT_MODULO;
      //   mask = betMask;
      // } else {
        // Larger modulos specify the right edge of half-open interval of
        // winning bet outcomes.
        require (betMask > 0 && betMask <= 100, "High modulo range, betMask larger than modulo.");
        // rollUnder = betMask;
      // }
      
      // Winning amount and jackpot increase.
      uint possibleWinAmount;
      uint jackpotFee;
      
      (possibleWinAmount, jackpotFee) = getDiceWinAmount(amount, betMask);
      
      // Enforce max profit limit.
      require (possibleWinAmount <= amount + maxProfit, "maxProfit limit violation. ");
      
      // Lock funds.
      lockedInBets += uint128(possibleWinAmount);
      jackpotSize += uint128(jackpotFee);
      
      // Check whether contract has enough funds to process this bet.
      require (jackpotSize + lockedInBets <= address(this).balance, "Cannot afford to lose this bet.");
      
      // Record commit in logs.
      emit Commit(commit);

      // Store bet parameters on blockchain.
      bet.amount = amount;
      // bet.modulo = uint8(modulo);
      bet.rollUnder = uint8(betMask);
      bet.placeBlockNumber = uint40(block.number);
      bet.mask = uint40(mask);
      bet.gambler = msg.sender;
      bet.inviter = inviter;

      uint accuAmount = accuBetAmount[msg.sender];
      accuAmount = accuAmount + amount;
      accuBetAmount[msg.sender] = accuAmount;
    }

    function getMyAccuAmount() external view returns (uint){
      return accuBetAmount[msg.sender];
    }
    
    // This is the method used to settle 99% of bets. To process a bet with a specific
    // "commit", settleBet should supply a "reveal" number that would Keccak256-hash to
    // "commit". "blockHash" is the block hash of placeBet block as seen by croupier; it
    // is additionally asserted to prevent changing the bet outcomes on Ethereum reorgs.
    function settleBet(uint reveal, bytes32 blockHash) external onlyCroupier {
      uint commit = uint(keccak256(abi.encodePacked(reveal)));
      
      Bet storage bet = bets[commit];
      uint placeBlockNumber = bet.placeBlockNumber;
      
      // Check that bet has not expired yet (see comment to BET_EXPIRATION_BLOCKS).
      require (block.number > placeBlockNumber, "settleBet in the same block as placeBet, or before.");
      require (block.number <= placeBlockNumber + BET_EXPIRATION_BLOCKS, "Blockhash can't be queried by EVM.");
      require (blockhash(placeBlockNumber) == blockHash);
      
      // Settle bet using reveal and blockHash as entropy sources.
      settleBetCommon(bet, reveal, blockHash);
    }
    
    // This method is used to settle a bet that was mined into an uncle block. At this
    // point the player was shown some bet outcome, but the blockhash at placeBet height
    // is different because of Ethereum chain reorg. We supply a full merkle proof of the
    // placeBet transaction receipt to provide untamperable evidence that uncle block hash
    // indeed was present on-chain at some point.
    function settleBetUncleMerkleProof(uint reveal, uint40 canonicalBlockNumber) external onlyCroupier {
      // "commit" for bet settlement can only be obtained by hashing a "reveal".
      uint commit = uint(keccak256(abi.encodePacked(reveal)));
      
      Bet storage bet = bets[commit];
      
      // Check that canonical block hash can still be verified.
      require (block.number <= canonicalBlockNumber + BET_EXPIRATION_BLOCKS, "Blockhash can't be queried by EVM.");
      
      // Verify placeBet receipt.
      requireCorrectReceipt(4 + 32 + 32 + 4);
      
      // Reconstruct canonical & uncle block hashes from a receipt merkle proof, verify them.
      bytes32 canonicalHash;
      bytes32 uncleHash;
      (canonicalHash, uncleHash) = verifyMerkleProof(commit, 4 + 32 + 32);
      require (blockhash(canonicalBlockNumber) == canonicalHash);
      
      // Settle bet using reveal and uncleHash as entropy sources.
      settleBetCommon(bet, reveal, uncleHash);
    }
    
    // Common settlement code for settleBet & settleBetUncleMerkleProof.
    function settleBetCommon(Bet storage bet, uint reveal, bytes32 entropyBlockHash) private {
      // Fetch bet parameters into local variables (to save gas).
      uint amount = bet.amount;
      // uint modulo = bet.modulo;
      uint rollUnder = bet.rollUnder;
      address gambler = bet.gambler;
      
      // Check that bet is in 'active' state.
      require (amount != 0, "Bet should be in an 'active' state");

      applyVIPLevel(gambler, amount);
      
      // Move bet into 'processed' state already.
      bet.amount = 0;
      
      // The RNG - combine "reveal" and blockhash of placeBet using Keccak256. Miners
      // are not aware of "reveal" and cannot deduce it from "commit" (as Keccak256
      // preimage is intractable), and house is unable to alter the "reveal" after
      // placeBet have been mined (as Keccak256 collision finding is also intractable).
      bytes32 entropy = keccak256(abi.encodePacked(reveal, entropyBlockHash));
      
      // Do a roll by taking a modulo of entropy. Compute winning amount.
      uint modulo = 100;
      uint dice = uint(entropy) % modulo;
      
      uint diceWinAmount;
      uint _jackpotFee;
      (diceWinAmount, _jackpotFee) = getDiceWinAmount(amount, rollUnder);
      
      uint diceWin = 0;
      uint jackpotWin = 0;
      
      // Determine dice outcome.
      if (modulo <= MAX_MASK_MODULO) {
        // For small modulo games, check the outcome against a bit mask.
        if ((2 ** dice) & bet.mask != 0) {
          diceWin = diceWinAmount;
        }
        
        } else {
          // For larger modulos, check inclusion into half-open interval.
          if (dice < rollUnder) {
            diceWin = diceWinAmount;
          }
          
        }
        
        // Unlock the bet amount, regardless of the outcome.
        lockedInBets -= uint128(diceWinAmount);
        
        // Roll for a jackpot (if eligible).
        if (amount >= MIN_JACKPOT_BET) {
          // The second modulo, statistically independent from the "main" dice roll.
          // Effectively you are playing two games at once!
          // uint jackpotRng = (uint(entropy) / modulo) % JACKPOT_MODULO;
          
          // Bingo!
          if ((uint(entropy) / modulo) % JACKPOT_MODULO == 0) {
            jackpotWin = jackpotSize;
            jackpotSize = 0;
          }
        }
        
        // Log jackpot win.
        if (jackpotWin > 0) {
          emit JackpotPayment(gambler, jackpotWin, dice, rollUnder, amount);
        }
        
        if(bet.inviter != address(0)){
          // 친구 초대하면 친구한대 15% 때어줌
          // uint inviterFee = amount * HOUSE_EDGE_PERCENT / 100 * 15 /100;
          bet.inviter.transfer(amount * HOUSE_EDGE_PERCENT / 100 * 10 /100);
        }
        todaysRewardSize += amount * HOUSE_EDGE_PERCENT / 100 * 9 /100;
        // Send the funds to gambler.
        sendFunds(gambler, diceWin + jackpotWin == 0 ? 1 wei : diceWin + jackpotWin, diceWin, dice, rollUnder, amount);
      }
      
      // Refund transaction - return the bet amount of a roll that was not processed in a
      // due timeframe. Processing such blocks is not possible due to EVM limitations (see
      // BET_EXPIRATION_BLOCKS comment above for details). In case you ever find yourself
      // in a situation like this, just contact the AceDice support, however nothing
      // precludes you from invoking this method yourself.
      function refundBet(uint commit) external {
        // Check that bet is in 'active' state.
        Bet storage bet = bets[commit];
        uint amount = bet.amount;
        
        require (amount != 0, "Bet should be in an 'active' state");
        
        // Check that bet has already expired.
        require (block.number > bet.placeBlockNumber + BET_EXPIRATION_BLOCKS, "Blockhash can't be queried by EVM.");
        
        // Move bet into 'processed' state, release funds.
        bet.amount = 0;
        
        uint diceWinAmount;
        uint jackpotFee;
        (diceWinAmount, jackpotFee) = getDiceWinAmount(amount, bet.rollUnder);
        
        lockedInBets -= uint128(diceWinAmount);
        jackpotSize -= uint128(jackpotFee);
        
        // Send the refund.
        sendFunds(bet.gambler, amount, amount, 0, 0, 0);
      }
      
      // Get the expected win amount after house edge is subtracted.
      function getDiceWinAmount(uint amount, uint rollUnder) private pure returns (uint winAmount, uint jackpotFee) {
        require (0 < rollUnder && rollUnder <= 100, "Win probability out of range.");
        
        jackpotFee = amount >= MIN_JACKPOT_BET ? JACKPOT_FEE : 0;
        
        uint houseEdge = amount * HOUSE_EDGE_PERCENT / 100;
        
        if (houseEdge < HOUSE_EDGE_MINIMUM_AMOUNT) {
          houseEdge = HOUSE_EDGE_MINIMUM_AMOUNT;
        }
        
        require (houseEdge + jackpotFee <= amount, "Bet doesn't even cover house edge.");
        winAmount = (amount - houseEdge - jackpotFee) * 100 / rollUnder;
      }
      
      // Helper routine to process the payment.
      function sendFunds(address beneficiary, uint amount, uint successLogAmount, uint dice, uint rollUnder, uint betAmount) private {
        if (beneficiary.send(amount)) {
          emit Payment(beneficiary, successLogAmount, dice, rollUnder, betAmount);
          } else {
            emit FailedPayment(beneficiary, amount);
          }
        }
        
        // This are some constants making O(1) population count in placeBet possible.
        // See whitepaper for intuition and proofs behind it.
        uint constant POPCNT_MULT = 0x0000000000002000000000100000000008000000000400000000020000000001;
        uint constant POPCNT_MASK = 0x0001041041041041041041041041041041041041041041041041041041041041;
        uint constant POPCNT_MODULO = 0x3F;
        
        // *** Merkle proofs.
        
        // This helpers are used to verify cryptographic proofs of placeBet inclusion into
        // uncle blocks. They are used to prevent bet outcome changing on Ethereum reorgs without
        // compromising the security of the smart contract. Proof data is appended to the input data
        // in a simple prefix length format and does not adhere to the ABI.
        // Invariants checked:
        // - receipt trie entry contains a (1) successful transaction (2) directed at this smart
        // contract (3) containing commit as a payload.
        // - receipt trie entry is a part of a valid merkle proof of a block header
        // - the block header is a part of uncle list of some block on canonical chain
        // The implementation is optimized for gas cost and relies on the specifics of Ethereum internal data structures.
        // Read the whitepaper for details.
        
        // Helper to verify a full merkle proof starting from some seedHash (usually commit). "offset" is the location of the proof
        // beginning in the calldata.
        function verifyMerkleProof(uint seedHash, uint offset) pure private returns (bytes32 blockHash, bytes32 uncleHash) {
          // (Safe) assumption - nobody will write into RAM during this method invocation.
        uint scratchBuf1; assembly { scratchBuf1 := mload(0x40) }
        
        uint uncleHeaderLength; uint blobLength; uint shift; uint hashSlot;
        
        // Verify merkle proofs up to uncle block header. Calldata layout is:
        // - 2 byte big-endian slice length
        // - 2 byte big-endian offset to the beginning of previous slice hash within the current slice (should be zeroed)
        // - followed by the current slice verbatim
        for (;; offset += blobLength) {
        assembly { blobLength := and(calldataload(sub(offset, 30)), 0xffff) }
        if (blobLength == 0) {
          // Zero slice length marks the end of uncle proof.
          break;
        }
        
      assembly { shift := and(calldataload(sub(offset, 28)), 0xffff) }
      require (shift + 32 <= blobLength, "Shift bounds check.");
      
      offset += 4;
    assembly { hashSlot := calldataload(add(offset, shift)) }
    require (hashSlot == 0, "Non-empty hash slot.");
    
    assembly {
      calldatacopy(scratchBuf1, offset, blobLength)
      mstore(add(scratchBuf1, shift), seedHash)
      seedHash := sha3(scratchBuf1, blobLength)
      uncleHeaderLength := blobLength
    }
  }
  
  // At this moment the uncle hash is known.
  uncleHash = bytes32(seedHash);
  
  // Construct the uncle list of a canonical block.
  uint scratchBuf2 = scratchBuf1 + uncleHeaderLength;
uint unclesLength; assembly { unclesLength := and(calldataload(sub(offset, 28)), 0xffff) }
        uint unclesShift;  assembly { unclesShift := and(calldataload(sub(offset, 26)), 0xffff) }
        require (unclesShift + uncleHeaderLength <= unclesLength, "Shift bounds check.");

        offset += 6;
        assembly { calldatacopy(scratchBuf2, offset, unclesLength) }
        memcpy(scratchBuf2 + unclesShift, scratchBuf1, uncleHeaderLength);

        assembly { seedHash := sha3(scratchBuf2, unclesLength) }

        offset += unclesLength;

        // Verify the canonical block header using the computed sha3Uncles.
        assembly {
            blobLength := and(calldataload(sub(offset, 30)), 0xffff)
            shift := and(calldataload(sub(offset, 28)), 0xffff)
        }
        require (shift + 32 <= blobLength, "Shift bounds check.");

        offset += 4;
        assembly { hashSlot := calldataload(add(offset, shift)) }
        require (hashSlot == 0, "Non-empty hash slot.");

        assembly {
            calldatacopy(scratchBuf1, offset, blobLength)
            mstore(add(scratchBuf1, shift), seedHash)

            // At this moment the canonical block hash is known.
            blockHash := sha3(scratchBuf1, blobLength)
        }
    }

    // Helper to check the placeBet receipt. "offset" is the location of the proof beginning in the calldata.
    // RLP layout: [triePath, str([status, cumGasUsed, bloomFilter, [[address, [topics], data]])]
    function requireCorrectReceipt(uint offset) view private {
        uint leafHeaderByte; assembly { leafHeaderByte := byte(0, calldataload(offset)) }

        require (leafHeaderByte >= 0xf7, "Receipt leaf longer than 55 bytes.");
        offset += leafHeaderByte - 0xf6;

        uint pathHeaderByte; assembly { pathHeaderByte := byte(0, calldataload(offset)) }

        if (pathHeaderByte <= 0x7f) {
            offset += 1;

        } else {
            require (pathHeaderByte >= 0x80 && pathHeaderByte <= 0xb7, "Path is an RLP string.");
            offset += pathHeaderByte - 0x7f;
        }

        uint receiptStringHeaderByte; assembly { receiptStringHeaderByte := byte(0, calldataload(offset)) }
        require (receiptStringHeaderByte == 0xb9, "Receipt string is always at least 256 bytes long, but less than 64k.");
        offset += 3;

        uint receiptHeaderByte; assembly { receiptHeaderByte := byte(0, calldataload(offset)) }
        require (receiptHeaderByte == 0xf9, "Receipt is always at least 256 bytes long, but less than 64k.");
        offset += 3;

        uint statusByte; assembly { statusByte := byte(0, calldataload(offset)) }
        require (statusByte == 0x1, "Status should be success.");
        offset += 1;

        uint cumGasHeaderByte; assembly { cumGasHeaderByte := byte(0, calldataload(offset)) }
        if (cumGasHeaderByte <= 0x7f) {
            offset += 1;

        } else {
            require (cumGasHeaderByte >= 0x80 && cumGasHeaderByte <= 0xb7, "Cumulative gas is an RLP string.");
            offset += cumGasHeaderByte - 0x7f;
        }

        uint bloomHeaderByte; assembly { bloomHeaderByte := byte(0, calldataload(offset)) }
        require (bloomHeaderByte == 0xb9, "Bloom filter is always 256 bytes long.");
        offset += 256 + 3;

        uint logsListHeaderByte; assembly { logsListHeaderByte := byte(0, calldataload(offset)) }
        require (logsListHeaderByte == 0xf8, "Logs list is less than 256 bytes long.");
        offset += 2;

        uint logEntryHeaderByte; assembly { logEntryHeaderByte := byte(0, calldataload(offset)) }
        require (logEntryHeaderByte == 0xf8, "Log entry is less than 256 bytes long.");
        offset += 2;

        uint addressHeaderByte; assembly { addressHeaderByte := byte(0, calldataload(offset)) }
        require (addressHeaderByte == 0x94, "Address is 20 bytes long.");

        uint logAddress; assembly { logAddress := and(calldataload(sub(offset, 11)), 0xffffffffffffffffffffffffffffffffffffffff) }
        require (logAddress == uint(address(this)));
    }

    // Memory copy.
    function memcpy(uint dest, uint src, uint len) pure private {
        // Full 32 byte words
        for(; len >= 32; len -= 32) {
            assembly { mstore(dest, mload(src)) }
            dest += 32; src += 32;
        }

        // Remaining bytes
        uint mask = 256 ** (32 - len) - 1;
        assembly {
            let srcpart := and(mload(src), not(mask))
            let destpart := and(mload(dest), mask)
            mstore(dest, or(destpart, srcpart))
        }
    }

    function thisBalance() public view returns(uint) {
        return address(this).balance;
    }

    function setAvatarIndex(uint index) external{
      require (index >=0 && index <= 100, "avatar index should be in range");
      Profile storage profile = profiles[msg.sender];
      profile.avatarIndex = index;
    }

    function setNickName(string nickName) external{
      Profile storage profile = profiles[msg.sender];
      profile.nickName = nickName;
    }

    function getProfile() external view returns(uint, string){
      Profile storage profile = profiles[msg.sender];
      return (profile.avatarIndex, profile.nickName);
    }

    function payTodayReward(address to) external onlyOwner {
      uint prize = todaysRewardSize / 2;
      todaysRewardSize = todaysRewardSize - prize;
      if(to.send(prize)){
        emit TodaysRankingPayment(to, prize);
      }
    }
}