pragma solidity 0.4.26;


library Buffer {
    
    struct buffer {
        bytes buf;
        uint capacity;
    }

    
    function init(buffer memory buf, uint capacity) internal pure returns(buffer memory) {
        if (capacity % 32 != 0) {
            capacity += 32 - (capacity % 32);
        }
        
        buf.capacity = capacity;
        assembly {
            let ptr := mload(0x40)
            mstore(buf, ptr)
            mstore(ptr, 0)
            mstore(0x40, add(32, add(ptr, capacity)))
        }
        return buf;
    }

    
    function fromBytes(bytes memory b) internal pure returns(buffer memory) {
        buffer memory buf;
        buf.buf = b;
        buf.capacity = b.length;
        return buf;
    }

    function resize(buffer memory buf, uint capacity) private pure {
        bytes memory oldbuf = buf.buf;
        init(buf, capacity);
        append(buf, oldbuf);
    }

    function max(uint a, uint b) private pure returns(uint) {
        if (a > b) {
            return a;
        }
        return b;
    }

    
    function truncate(buffer memory buf) internal pure returns (buffer memory) {
        assembly {
            let bufptr := mload(buf)
            mstore(bufptr, 0)
        }
        return buf;
    }

    
    function write(buffer memory buf, uint off, bytes memory data, uint len) internal pure returns(buffer memory) {
        require(len <= data.length);

        if (off + len > buf.capacity) {
            resize(buf, max(buf.capacity, len + off) * 2);
        }

        uint dest;
        uint src;
        assembly {
            
            let bufptr := mload(buf)
            
            let buflen := mload(bufptr)
            
            dest := add(add(bufptr, 32), off)
            
            if gt(add(len, off), buflen) {
                mstore(bufptr, add(len, off))
            }
            src := add(data, 32)
        }

        
        for (; len >= 32; len -= 32) {
            assembly {
                mstore(dest, mload(src))
            }
            dest += 32;
            src += 32;
        }

        
        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))
        }

        return buf;
    }

    
    function append(buffer memory buf, bytes memory data, uint len) internal pure returns (buffer memory) {
        return write(buf, buf.buf.length, data, len);
    }

    
    function append(buffer memory buf, bytes memory data) internal pure returns (buffer memory) {
        return write(buf, buf.buf.length, data, data.length);
    }

    
    function writeUint8(buffer memory buf, uint off, uint8 data) internal pure returns(buffer memory) {
        if (off >= buf.capacity) {
            resize(buf, buf.capacity * 2);
        }

        assembly {
            
            let bufptr := mload(buf)
            
            let buflen := mload(bufptr)
            
            let dest := add(add(bufptr, off), 32)
            mstore8(dest, data)
            
            if eq(off, buflen) {
                mstore(bufptr, add(buflen, 1))
            }
        }
        return buf;
    }

    
    function appendUint8(buffer memory buf, uint8 data) internal pure returns(buffer memory) {
        return writeUint8(buf, buf.buf.length, data);
    }

    
    function write(buffer memory buf, uint off, bytes32 data, uint len) private pure returns(buffer memory) {
        if (len + off > buf.capacity) {
            resize(buf, (len + off) * 2);
        }

        uint mask = 256 ** len - 1;
        
        data = data >> (8 * (32 - len));
        assembly {
            
            let bufptr := mload(buf)
            
            let dest := add(add(bufptr, off), len)
            mstore(dest, or(and(mload(dest), not(mask)), data))
            
            if gt(add(off, len), mload(bufptr)) {
                mstore(bufptr, add(off, len))
            }
        }
        return buf;
    }

    
    function writeBytes20(buffer memory buf, uint off, bytes20 data) internal pure returns (buffer memory) {
        return write(buf, off, bytes32(data), 20);
    }

    
    function appendBytes20(buffer memory buf, bytes20 data) internal pure returns (buffer memory) {
        return write(buf, buf.buf.length, bytes32(data), 20);
    }

    
    function appendBytes32(buffer memory buf, bytes32 data) internal pure returns (buffer memory) {
        return write(buf, buf.buf.length, data, 32);
    }

    
    function writeInt(buffer memory buf, uint off, uint data, uint len) private pure returns(buffer memory) {
        if (len + off > buf.capacity) {
            resize(buf, (len + off) * 2);
        }

        uint mask = 256 ** len - 1;
        assembly {
            
            let bufptr := mload(buf)
            
            let dest := add(add(bufptr, off), len)
            mstore(dest, or(and(mload(dest), not(mask)), data))
            
            if gt(add(off, len), mload(bufptr)) {
                mstore(bufptr, add(off, len))
            }
        }
        return buf;
    }

    
    function appendInt(buffer memory buf, uint data, uint len) internal pure returns(buffer memory) {
        return writeInt(buf, buf.buf.length, data, len);
    }
}

library CBOR {
    using Buffer for Buffer.buffer;

    uint8 private constant MAJOR_TYPE_INT = 0;
    uint8 private constant MAJOR_TYPE_NEGATIVE_INT = 1;
    uint8 private constant MAJOR_TYPE_BYTES = 2;
    uint8 private constant MAJOR_TYPE_STRING = 3;
    uint8 private constant MAJOR_TYPE_ARRAY = 4;
    uint8 private constant MAJOR_TYPE_MAP = 5;
    uint8 private constant MAJOR_TYPE_CONTENT_FREE = 7;

    function encodeType(Buffer.buffer memory buf, uint8 major, uint value) private pure {
        if(value <= 23) {
            buf.appendUint8(uint8((major << 5) | value));
        } else if(value <= 0xFF) {
            buf.appendUint8(uint8((major << 5) | 24));
            buf.appendInt(value, 1);
        } else if(value <= 0xFFFF) {
            buf.appendUint8(uint8((major << 5) | 25));
            buf.appendInt(value, 2);
        } else if(value <= 0xFFFFFFFF) {
            buf.appendUint8(uint8((major << 5) | 26));
            buf.appendInt(value, 4);
        } else if(value <= 0xFFFFFFFFFFFFFFFF) {
            buf.appendUint8(uint8((major << 5) | 27));
            buf.appendInt(value, 8);
        }
    }

    function encodeIndefiniteLengthType(Buffer.buffer memory buf, uint8 major) private pure {
        buf.appendUint8(uint8((major << 5) | 31));
    }

    function encodeUInt(Buffer.buffer memory buf, uint value) internal pure {
        encodeType(buf, MAJOR_TYPE_INT, value);
    }

    function encodeInt(Buffer.buffer memory buf, int value) internal pure {
        if(value >= 0) {
            encodeType(buf, MAJOR_TYPE_INT, uint(value));
        } else {
            encodeType(buf, MAJOR_TYPE_NEGATIVE_INT, uint(-1 - value));
        }
    }

    function encodeBytes(Buffer.buffer memory buf, bytes value) internal pure {
        encodeType(buf, MAJOR_TYPE_BYTES, value.length);
        buf.append(value);
    }

    function encodeString(Buffer.buffer memory buf, string value) internal pure {
        encodeType(buf, MAJOR_TYPE_STRING, bytes(value).length);
        buf.append(bytes(value));
    }

    function startArray(Buffer.buffer memory buf) internal pure {
        encodeIndefiniteLengthType(buf, MAJOR_TYPE_ARRAY);
    }

    function startMap(Buffer.buffer memory buf) internal pure {
        encodeIndefiniteLengthType(buf, MAJOR_TYPE_MAP);
    }

    function endSequence(Buffer.buffer memory buf) internal pure {
        encodeIndefiniteLengthType(buf, MAJOR_TYPE_CONTENT_FREE);
    }
}

library Chainlink {
  uint256 internal constant defaultBufferSize = 256;

  using CBOR for Buffer.buffer;

  struct Request {
    bytes32 id;
    address callbackAddress;
    bytes4 callbackFunctionId;
    uint256 nonce;
    Buffer.buffer buf;
  }

  
  function initialize(
    Request memory self,
    bytes32 _id,
    address _callbackAddress,
    bytes4 _callbackFunction
  ) internal pure returns (Chainlink.Request memory) {
    Buffer.init(self.buf, defaultBufferSize);
    self.id = _id;
    self.callbackAddress = _callbackAddress;
    self.callbackFunctionId = _callbackFunction;
    return self;
  }

  
  function setBuffer(Request memory self, bytes _data)
    internal pure
  {
    Buffer.init(self.buf, _data.length);
    Buffer.append(self.buf, _data);
  }

  
  function add(Request memory self, string _key, string _value)
    internal pure
  {
    self.buf.encodeString(_key);
    self.buf.encodeString(_value);
  }

  
  function addBytes(Request memory self, string _key, bytes _value)
    internal pure
  {
    self.buf.encodeString(_key);
    self.buf.encodeBytes(_value);
  }

  
  function addInt(Request memory self, string _key, int256 _value)
    internal pure
  {
    self.buf.encodeString(_key);
    self.buf.encodeInt(_value);
  }

  
  function addUint(Request memory self, string _key, uint256 _value)
    internal pure
  {
    self.buf.encodeString(_key);
    self.buf.encodeUInt(_value);
  }

  
  function addStringArray(Request memory self, string _key, string[] memory _values)
    internal pure
  {
    self.buf.encodeString(_key);
    self.buf.startArray();
    for (uint256 i = 0; i < _values.length; i++) {
      self.buf.encodeString(_values[i]);
    }
    self.buf.endSequence();
  }
}

contract ENSResolver {
  function addr(bytes32 node) public view returns (address);
}

interface ENSInterface {

    
    event NewOwner(bytes32 indexed node, bytes32 indexed label, address owner);

    
    event Transfer(bytes32 indexed node, address owner);

    
    event NewResolver(bytes32 indexed node, address resolver);

    
    event NewTTL(bytes32 indexed node, uint64 ttl);


    function setSubnodeOwner(bytes32 node, bytes32 label, address owner) external;
    function setResolver(bytes32 node, address resolver) external;
    function setOwner(bytes32 node, address owner) external;
    function setTTL(bytes32 node, uint64 ttl) external;
    function owner(bytes32 node) external view returns (address);
    function resolver(bytes32 node) external view returns (address);
    function ttl(bytes32 node) external view returns (uint64);

}

interface LinkTokenInterface {
  function allowance(address owner, address spender) external returns (bool success);
  function approve(address spender, uint256 value) external returns (bool success);
  function balanceOf(address owner) external returns (uint256 balance);
  function decimals() external returns (uint8 decimalPlaces);
  function decreaseApproval(address spender, uint256 addedValue) external returns (bool success);
  function increaseApproval(address spender, uint256 subtractedValue) external;
  function name() external returns (string tokenName);
  function symbol() external returns (string tokenSymbol);
  function totalSupply() external returns (uint256 totalTokensIssued);
  function transfer(address to, uint256 value) external returns (bool success);
  function transferAndCall(address to, uint256 value, bytes data) external returns (bool success);
  function transferFrom(address from, address to, uint256 value) external returns (bool success);
}

interface ChainlinkRequestInterface {
  function oracleRequest(
    address sender,
    uint256 payment,
    bytes32 id,
    address callbackAddress,
    bytes4 callbackFunctionId,
    uint256 nonce,
    uint256 version,
    bytes data
  ) external;

  function cancelOracleRequest(
    bytes32 requestId,
    uint256 payment,
    bytes4 callbackFunctionId,
    uint256 expiration
  ) external;
}

interface PointerInterface {
  function getAddress() external view returns (address);
}

library SafeMath {

  
  function mul(uint256 _a, uint256 _b) internal pure returns (uint256 c) {
    
    
    
    if (_a == 0) {
      return 0;
    }

    c = _a * _b;
    assert(c / _a == _b);
    return c;
  }

  
  function div(uint256 _a, uint256 _b) internal pure returns (uint256) {
    
    
    
    return _a / _b;
  }

  
  function sub(uint256 _a, uint256 _b) internal pure returns (uint256) {
    assert(_b <= _a);
    return _a - _b;
  }

  
  function add(uint256 _a, uint256 _b) internal pure returns (uint256 c) {
    c = _a + _b;
    assert(c >= _a);
    return c;
  }
}

contract ChainlinkClient {
  using Chainlink for Chainlink.Request;
  using SafeMath for uint256;

  uint256 constant internal LINK = 10**18;
  uint256 constant private AMOUNT_OVERRIDE = 0;
  address constant private SENDER_OVERRIDE = 0x0;
  uint256 constant private ARGS_VERSION = 1;
  bytes32 constant private ENS_TOKEN_SUBNAME = keccak256("link");
  bytes32 constant private ENS_ORACLE_SUBNAME = keccak256("oracle");
  address constant private LINK_TOKEN_POINTER = 0xC89bD4E1632D3A43CB03AAAd5262cbe4038Bc571;

  ENSInterface private ens;
  bytes32 private ensNode;
  LinkTokenInterface private link;
  ChainlinkRequestInterface private oracle;
  uint256 private requests = 1;
  mapping(bytes32 => address) private pendingRequests;

  event ChainlinkRequested(bytes32 indexed id);
  event ChainlinkFulfilled(bytes32 indexed id);
  event ChainlinkCancelled(bytes32 indexed id);

  
  function buildChainlinkRequest(
    bytes32 _specId,
    address _callbackAddress,
    bytes4 _callbackFunctionSignature
  ) internal pure returns (Chainlink.Request memory) {
    Chainlink.Request memory req;
    return req.initialize(_specId, _callbackAddress, _callbackFunctionSignature);
  }

  
  function sendChainlinkRequest(Chainlink.Request memory _req, uint256 _payment)
    internal
    returns (bytes32)
  {
    return sendChainlinkRequestTo(oracle, _req, _payment);
  }

  
  function sendChainlinkRequestTo(address _oracle, Chainlink.Request memory _req, uint256 _payment)
    internal
    returns (bytes32 requestId)
  {
    requestId = keccak256(abi.encodePacked(this, requests));
    _req.nonce = requests;
    pendingRequests[requestId] = _oracle;
    emit ChainlinkRequested(requestId);
    require(link.transferAndCall(_oracle, _payment, encodeRequest(_req)), "unable to transferAndCall to oracle");
    requests += 1;

    return requestId;
  }

  
  function cancelChainlinkRequest(
    bytes32 _requestId,
    uint256 _payment,
    bytes4 _callbackFunc,
    uint256 _expiration
  )
    internal
  {
    ChainlinkRequestInterface requested = ChainlinkRequestInterface(pendingRequests[_requestId]);
    delete pendingRequests[_requestId];
    emit ChainlinkCancelled(_requestId);
    requested.cancelOracleRequest(_requestId, _payment, _callbackFunc, _expiration);
  }

  
  function setChainlinkOracle(address _oracle) internal {
    oracle = ChainlinkRequestInterface(_oracle);
  }

  
  function setChainlinkToken(address _link) internal {
    link = LinkTokenInterface(_link);
  }

  
  function setPublicChainlinkToken() internal {
    setChainlinkToken(PointerInterface(LINK_TOKEN_POINTER).getAddress());
  }

  
  function chainlinkTokenAddress()
    internal
    view
    returns (address)
  {
    return address(link);
  }

  
  function chainlinkOracleAddress()
    internal
    view
    returns (address)
  {
    return address(oracle);
  }

  
  function addChainlinkExternalRequest(address _oracle, bytes32 _requestId)
    internal
    notPendingRequest(_requestId)
  {
    pendingRequests[_requestId] = _oracle;
  }

  
  function useChainlinkWithENS(address _ens, bytes32 _node)
    internal
  {
    ens = ENSInterface(_ens);
    ensNode = _node;
    bytes32 linkSubnode = keccak256(abi.encodePacked(ensNode, ENS_TOKEN_SUBNAME));
    ENSResolver resolver = ENSResolver(ens.resolver(linkSubnode));
    setChainlinkToken(resolver.addr(linkSubnode));
    updateChainlinkOracleWithENS();
  }

  
  function updateChainlinkOracleWithENS()
    internal
  {
    bytes32 oracleSubnode = keccak256(abi.encodePacked(ensNode, ENS_ORACLE_SUBNAME));
    ENSResolver resolver = ENSResolver(ens.resolver(oracleSubnode));
    setChainlinkOracle(resolver.addr(oracleSubnode));
  }

  
  function encodeRequest(Chainlink.Request memory _req)
    private
    view
    returns (bytes memory)
  {
    return abi.encodeWithSelector(
      oracle.oracleRequest.selector,
      SENDER_OVERRIDE, 
      AMOUNT_OVERRIDE, 
      _req.id,
      _req.callbackAddress,
      _req.callbackFunctionId,
      _req.nonce,
      ARGS_VERSION,
      _req.buf.buf);
  }

  
  function validateChainlinkCallback(bytes32 _requestId)
    internal
    recordChainlinkFulfillment(_requestId)
    
  {}

  
  modifier recordChainlinkFulfillment(bytes32 _requestId) {
    require(msg.sender == pendingRequests[_requestId], "Source must be the oracle of the request");
    delete pendingRequests[_requestId];
    emit ChainlinkFulfilled(_requestId);
    _;
  }

  
  modifier notPendingRequest(bytes32 _requestId) {
    require(pendingRequests[_requestId] == address(0), "Request is already pending");
    _;
  }
}

contract DSMath {
    
    

    function add(uint256 x, uint256 y) pure internal returns (uint256 z) {
        assert((z = x + y) >= x);
    }

    function sub(uint256 x, uint256 y) pure internal returns (uint256 z) {
        assert((z = x - y) <= x);
    }

    function mul(uint256 x, uint256 y) pure internal returns (uint256 z) {
        assert((z = x * y) >= x);
    }
    
    function div(uint256 x, uint256 y) pure internal returns (uint256 z) {
        require(y > 0);
        z = x / y;
    }
    
    function min(uint256 x, uint256 y) pure internal returns (uint256 z) {
        return x <= y ? x : y;
    }
    function max(uint256 x, uint256 y) pure internal returns (uint256 z) {
        return x >= y ? x : y;
    }

    


    function hadd(uint128 x, uint128 y) pure internal returns (uint128 z) {
        assert((z = x + y) >= x);
    }

    function hsub(uint128 x, uint128 y) pure internal returns (uint128 z) {
        assert((z = x - y) <= x);
    }

    function hmul(uint128 x, uint128 y) pure internal returns (uint128 z) {
        assert((z = x * y) >= x);
    }

    function hdiv(uint128 x, uint128 y) pure internal returns (uint128 z) {
        assert(y > 0);
        z = x / y;
    }

    function hmin(uint128 x, uint128 y) pure internal returns (uint128 z) {
        return x <= y ? x : y;
    }
    function hmax(uint128 x, uint128 y) pure internal returns (uint128 z) {
        return x >= y ? x : y;
    }


    

    function imin(int256 x, int256 y) pure internal returns (int256 z) {
        return x <= y ? x : y;
    }
    function imax(int256 x, int256 y) pure internal returns (int256 z) {
        return x >= y ? x : y;
    }

    

    uint128 constant WAD = 10 ** 18;

    function wadd(uint128 x, uint128 y) pure internal returns (uint128) {
        return hadd(x, y);
    }

    function wsub(uint128 x, uint128 y) pure internal returns (uint128) {
        return hsub(x, y);
    }

    function wmul(uint128 x, uint128 y) view internal returns (uint128 z) {
        z = cast((uint256(x) * y + WAD / 2) / WAD);
    }

    function wdiv(uint128 x, uint128 y) view internal returns (uint128 z) {
        z = cast((uint256(x) * WAD + y / 2) / y);
    }

    function wmin(uint128 x, uint128 y) pure internal returns (uint128) {
        return hmin(x, y);
    }
    function wmax(uint128 x, uint128 y) pure internal returns (uint128) {
        return hmax(x, y);
    }

    

    uint128 constant RAY = 10 ** 27;

    function radd(uint128 x, uint128 y) pure internal returns (uint128) {
        return hadd(x, y);
    }

    function rsub(uint128 x, uint128 y) pure internal returns (uint128) {
        return hsub(x, y);
    }

    function rmul(uint128 x, uint128 y) view internal returns (uint128 z) {
        z = cast((uint256(x) * y + RAY / 2) / RAY);
    }

    function rdiv(uint128 x, uint128 y) view internal returns (uint128 z) {
        z = cast((uint256(x) * RAY + y / 2) / y);
    }

    function rpow(uint128 x, uint64 n) view internal returns (uint128 z) {
        
        
        
        
        
        
        
        
        
        
        
        
        
        

        z = n % 2 != 0 ? x : RAY;

        for (n /= 2; n != 0; n /= 2) {
            x = rmul(x, x);

            if (n % 2 != 0) {
                z = rmul(z, x);
            }
        }
    }

    function rmin(uint128 x, uint128 y) pure internal returns (uint128) {
        return hmin(x, y);
    }
    function rmax(uint128 x, uint128 y) pure internal returns (uint128) {
        return hmax(x, y);
    }

    function cast(uint256 x) pure internal returns (uint128 z) {
        assert((z = uint128(x)) == x);
    }

}

contract ERC20Basic {
  uint256 public totalSupply;
  function balanceOf(address who) public view returns (uint256);
  function transfer(address to, uint256 value) public returns (bool);
  event Transfer(address indexed from, address indexed to, uint256 value);
}

contract ERC20 is ERC20Basic {
  function allowance(address owner, address spender) public view returns (uint256);
  function transferFrom(address from, address to, uint256 value) public returns (bool);
  function approve(address spender, uint256 value) public returns (bool);
  event Approval(address indexed owner, address indexed spender, uint256 value);
}

interface MedianizerInterface {
    function oracles(uint256) public view returns (address);
    function peek() public view returns (bytes32, bool);
    function read() public returns (bytes32);
    function poke() public;
    function poke(bytes32) public;
    function fund (uint256 amount, ERC20 token) public;
}

contract Oracle is DSMath {
    uint32  constant public DELAY = 900; 
    uint128 constant public prem = 1100000000000000000; 
    uint128 constant public turn = 1010000000000000000; 

    MedianizerInterface med; 

    uint32 public expiry;
    uint32 public timeout;
    uint128 assetPrice;
    uint128 public paymentTokenPrice;
    uint256 rewardAmount;

    mapping(bytes32 => AsyncRequest) asyncRequests;

    
    struct AsyncRequest {
        address rewardee;
        uint128 payment;
        uint128 disbursement;
        ERC20 token;
        bool assetPriceSet;
        bool paymentTokenPriceSet;
    }

    event SetAssetPrice(bytes32 queryId, uint128 assetPrice_, uint32 expiry_);

    event SetPaymentTokenPrice(bytes32 queryId, uint128 paymentTokenPrice_);

    event Reward(bytes32 queryId);

    
    function peek() public view returns (bytes32,bool) {
        return (bytes32(uint(assetPrice)), now < expiry);
    }

    
    function read() public view returns (bytes32) {
        assert(now < expiry);
        return bytes32(uint(assetPrice));
    }

    
    function setAssetPrice(bytes32 queryId, uint128 assetPrice_, uint32 expiry_) internal {
        asyncRequests[queryId].disbursement = 0;
        if (assetPrice_ >= wmul(assetPrice, turn) || assetPrice_ <= wdiv(assetPrice, turn)) {
            asyncRequests[queryId].disbursement = asyncRequests[queryId].payment;
        }
        assetPrice = assetPrice_;
        expiry = expiry_;
        med.poke();
        asyncRequests[queryId].assetPriceSet = true;
        if (asyncRequests[queryId].paymentTokenPriceSet) {reward(queryId);}

        emit SetAssetPrice(queryId, assetPrice_, expiry_);
    }

    
    function setPaymentTokenPrice(bytes32 queryId, uint128 paymentTokenPrice_) internal {
        paymentTokenPrice = paymentTokenPrice_;
        asyncRequests[queryId].paymentTokenPriceSet = true;
        if (asyncRequests[queryId].assetPriceSet) {reward(queryId);}

        emit SetPaymentTokenPrice(queryId, paymentTokenPrice_);
    }

    
    function reward(bytes32 queryId) internal {
        rewardAmount = wmul(wmul(paymentTokenPrice, asyncRequests[queryId].disbursement), prem);
        if (asyncRequests[queryId].token.balanceOf(address(this)) >= rewardAmount && asyncRequests[queryId].disbursement > 0) {
            require(asyncRequests[queryId].token.transfer(asyncRequests[queryId].rewardee, rewardAmount), "Oracle.reward: token transfer failed");
        }
        delete(asyncRequests[queryId]);

        emit Reward(queryId);
    }

    
    function setMaxReward(uint256 maxReward_) public;

    
    function setGasLimit(uint256 gasLimit_) public;
}

contract ChainLink is ChainlinkClient, Oracle {
    ERC20 link;
    uint256 maxReward; 

    bytes32 public lastQueryId;

    uint256 public constant DEFAULT_LINK_PAYMENT = 2 * LINK; 
    uint256 public constant ORACLE_EXPIRY = 12 hours; 

    mapping(bytes32 => bytes32) linkIdToQueryId;

    event Update(uint128 payment_, ERC20 token_);

    event ReturnAssetPrice(bytes32 requestId_, uint256 price_);

    event ReturnPaymentTokenPrice(bytes32 requestId_, uint256 price_);

    event Reward(bytes32 queryId);

    
    constructor(MedianizerInterface med_, ERC20 link_, address oracle_) public {
        med = med_;
        link = link_;
        setChainlinkToken(address(link_));
        setChainlinkOracle(oracle_);
        asyncRequests[lastQueryId].payment = uint128(DEFAULT_LINK_PAYMENT);
    }

    
    function bill() public view returns (uint256) {
        return asyncRequests[lastQueryId].payment;
    }

    
    function update(uint128 payment_, ERC20 token_) public { 
        require(uint32(now) > timeout, "ChainLink.update: now is less than timeout");
        require(link.transferFrom(msg.sender, address(this), uint(payment_)), "ChainLink.update: failed to transfer link from msg.sender");
        bytes32 queryId = getAssetPrice(payment_);
        lastQueryId = queryId;
        bytes32 linkId = getPaymentTokenPrice(payment_, queryId);
        linkIdToQueryId[linkId] = queryId;
        asyncRequests[queryId].rewardee = msg.sender;
        asyncRequests[queryId].payment = payment_;
        asyncRequests[queryId].token = token_;
        timeout = uint32(now) + DELAY;

        emit Update(payment_, token_);
    }

    function getAssetPrice(uint128) internal returns (bytes32);

    function getPaymentTokenPrice(uint128, bytes32) internal returns (bytes32);

    
    function returnAssetPrice(bytes32 requestId_, uint256 price_) public recordChainlinkFulfillment(requestId_) {
        setAssetPrice(requestId_, uint128(price_), uint32(now + ORACLE_EXPIRY));

        emit ReturnAssetPrice(requestId_, price_);
    }

    
    function returnPaymentTokenPrice(bytes32 requestId_, uint256 price_) public recordChainlinkFulfillment(requestId_) {
        setPaymentTokenPrice(linkIdToQueryId[requestId_], uint128(price_));

        emit ReturnPaymentTokenPrice(requestId_, price_);
    }

    
    function reward(bytes32 queryId) internal {
        rewardAmount = wmul(wmul(paymentTokenPrice, asyncRequests[queryId].disbursement), prem);
        if (asyncRequests[queryId].token.balanceOf(address(this)) >= min(maxReward, rewardAmount) && asyncRequests[queryId].disbursement > 0) {
            require(asyncRequests[queryId].token.transfer(asyncRequests[queryId].rewardee, min(maxReward, rewardAmount)), "ChainLink.reward: token transfer failed");
        }

        emit Reward(queryId);
    }

    
    function setMaxReward(uint256 maxReward_) public {
        require(msg.sender == address(med), "ChainLink.setMaxReward: msg.sender isn't medianizer address");
        maxReward = maxReward_;
    }

    
    function setGasLimit(uint256) public {
        require(msg.sender == address(med), "Oraclize.setGasLimit: msg.sender isn't medianizer address");
    }
}

contract Gemini is ChainLink {
    
    bytes32 constant UINT256_MUL_JOB = bytes32("f291f8597d174f4aa1983b0e27ae160f");

    
    

    
    bytes32 constant UINT256_MUL_JOB__LINK = bytes32("513907f96955437a8ac02a5d70e5bdea");

    
    

    
    constructor(MedianizerInterface med_, ERC20 link_, address oracle_) public ChainLink(med_, link_, oracle_) {}

    
    function getAssetPrice(uint128 payment_) internal returns (bytes32 queryId) {
        Chainlink.Request memory req = buildChainlinkRequest(UINT256_MUL_JOB, this, this.returnAssetPrice.selector);
        req.add("get", "https://api.gemini.com/v1/pubticker/btcusd");
        req.add("path", "last");
        req.addInt("times", WAD); 
        queryId = sendChainlinkRequest(req, div(payment_, 2)); 
    }

    
    function getPaymentTokenPrice(uint128 payment_, bytes32 queryId) internal returns (bytes32) {
        Chainlink.Request memory req = buildChainlinkRequest(UINT256_MUL_JOB__LINK, this, this.returnPaymentTokenPrice.selector);
        req.add("endpoint", "price");
        req.add("fsym", "LINK");
        req.add("tsyms", "USD");
        req.add("copyPath", "USD");
        req.addInt("times", WAD); 
        bytes32 linkId = sendChainlinkRequest(req, div(payment_, 2)); 
        linkIdToQueryId[linkId] = queryId;
        return linkId;
    }
}