// File: contracts/ape_lottery.sol



pragma solidity ^0.6.6;
import "@chainlink/contracts/src/v0.6/ChainlinkClient.sol";
import "@chainlink/contracts/src/v0.6/VRFConsumerBase.sol";


/*
Contract Created by

███████╗ ██╗   ██████╗░██╗██╗░░██╗██╗██╗░░░██╗███╗░░░███╗
███████║ ╚═╝   ██╔══██╗██║╚██╗██╔╝██║██║░░░██║████╗░████║
███████║ ██╗   ██████╔╝██║░╚███╔╝░██║██║░░░██║██╔████╔██║
████╔══╝ ╚═╝   ██╔═══╝░██║░██╔██╗░██║██║░░░██║██║╚██╔╝██║
████║██╗ ██╗   ██║░░░░░██║██╔╝╚██╗██║╚██████╔╝██║░╚═╝░██║
╚═══╝╚═╝ ╚═╝   ╚═╝░░░░░╚═╝╚═╝░░╚═╝╚═╝░╚═════╝░╚═╝░░░░░╚═╝

               █▄░█ █▀▀ ▀█▀   █░░ █▀█ ▀█▀ ▀█▀ █▀▀ █▀█ █▄█
               █░▀█ █▀░ ░█░   █▄▄ █▄█ ░█░ ░█░ ██▄ █▀▄ ░█░
               
Lottery on our website:
https://www.pixium-lottery.com

More Informations on our Medium articles:
https://medium.com/@PIXIUM
*/

interface INFTInterface {
    function transferFrom(address from, address to, uint256 tokenId) external payable;
}

contract Lottery is VRFConsumerBase {
    
    // The modifier allows certain functions to be used only by the owner
    modifier onlyBy(address _account)
    {
        require(msg.sender == _account);
        _;
        
    }

    // Constructor created in order to use Chainlink VRF (nb: more informations on our Medium article)
    constructor() 
        VRFConsumerBase(
            0xf0d54349aDdcf704F77AE15b96510dEA15cb7952, // VRF Coordinator Address
            0x514910771AF9Ca656af840dff83E8264EcF986CA  // LINK Token Address
        ) public
    
    // 
    {
        keyHash = 0xAA77729D3466CA35AE8D28B3BBAC7CC36A5031EFDC430821C02BC31A238AF445; // keyHash of Chainlink
        fee = 2 * 10 ** 18; 
    }
    //44444444444444444// modifier le constructor : adresses + fees=1 quand MainNet
    
    // Set up of the different variables and mappings (how to store the informations)
    address owner = address(0xFF577082f44d17721338BDFff52faA2D0C8f437E);
    address vrfCoordinator = address (0xf0d54349aDdcf704F77AE15b96510dEA15cb7952);
    address payable[] public players;
    address addressToSendNFT = OwnerOfTheNFT[1];

    enum LOTTERY_STATE { CLOSED, OPEN, CALCULATING_WINNER }
    enum WITHDRAWOWNER { OPEN, CLOSED }
    enum REFUND { CLOSED, OPEN }
    enum WITHDRAWNFT { OPEN, CLOSED }

    LOTTERY_STATE public lottery_state; 
    WITHDRAWOWNER public WithdrawOwner;
    REFUND public Refund;
    WITHDRAWNFT public WithdrawNFT;
    
    uint256 internal fee;
    uint256 public most_recent_random;
    uint256 public lotteryId;
    uint256 public totalTicketsSales = 0;
    uint256 public MINIMUM = 10000000000000000; // Price of the Ticket (0.01 eth)
    uint256 public TARGET = 8000000000000000000; // Target of the Lottery (8 eth)
    uint256 public ORACLE_PAYMENT = 2000000000000000000; // Chainlink Fees (2 link)

    mapping (address => uint) public QuantityOfTicket;
    mapping(uint => address) public ticketIndex;
    mapping (address => uint) public pendingWithdrawals;
    mapping (uint => address) public winners;
    mapping (uint => uint) public randomNumber;
    mapping (bytes32 => uint) public requestIds;
    mapping(uint256 => bool) public NFTIsDepositedInContract;
    mapping(uint256 => address) public OwnerOfTheNFT;
    
    bytes32 internal keyHash;

    bool private reentrancyLock = false;

    event Withdraw(address indexed account, uint amount);
    event DepositNFT(uint256 NFTId);
    event NFTGiven(uint256 NFTId);
    event TicketBought (address indexed account, uint NumberOfTicket);
    event initContract (address indexed account);
    event startLottery (address indexed account);
    event CloseLotteryAndPickWinner (address indexed account);
    event CancelLotteryAndRefund (address indexed account);
    
    // Interface of the BAYC contract (in order to interact with it)
    INFTInterface private NFTCore = INFTInterface(0xBC4CA0EdA7647A8aB7C2061c2E118A18a936f13D); //Address of the BAYC Contract
    
    /*

    █▀█ ▄▀█ █▀█ ▀█▀ █ █▀▀ █ █▀█ ▄▀█ ▀█▀ █ █▀█ █▄░█  
    █▀▀ █▀█ █▀▄ ░█░ █ █▄▄ █ █▀▀ █▀█ ░█░ █ █▄█ █░▀█  
    
        █▀█ ▄▀█ █▀█ ▀█▀
        █▀▀ █▀█ █▀▄ ░█░
    */

    /* 
    
    Fᴜɴᴄᴛɪᴏɴ ʙᴜʏᴛɪᴄᴋᴇᴛ
    
    Requires that the lottery has been launched, it allows participants to buy 1 or more tickets.
    The number of tickets increases your chance to win the big prize!
    /!\ WARNING /!\ the TotalToPay expect a value in WEI (the website makes automatically the conversion)
    */

    function BuyTicket (uint256 TotalToPay) public payable reentrancyGuard {
        require(TotalToPay % MINIMUM == 0);
        require(msg.sender != owner);
        require(msg.value >= TotalToPay, "Insufficient funds to purchase.");
        require(lottery_state == LOTTERY_STATE.OPEN);
        uint256 NumberOfTicket = div(TotalToPay,MINIMUM);
        for(uint256 i=0; i < NumberOfTicket; i++){
            totalTicketsSales+=1;
            ticketIndex[totalTicketsSales] = msg.sender;
        }
        QuantityOfTicket[msg.sender] += NumberOfTicket;
        pendingWithdrawals[owner] += msg.value;
        pendingWithdrawals[msg.sender] += msg.value;
        emit Withdraw(msg.sender, NumberOfTicket);
    } 
    
    /*
    
    █░░ █▀█ ▀█▀ ▀█▀ █▀▀ █▀█ █▄█
    █▄▄ █▄█ ░█░ ░█░ ██▄ █▀▄ ░█░
        
        █▀▄▀█ ▄▀█ █▄░█ ▄▀█ █▀▀ █▀▀ █▀▄▀█ █▀▀ █▄░█ ▀█▀
        █░▀░█ █▀█ █░▀█ █▀█ █▄█ ██▄ █░▀░█ ██▄ █░▀█ ░█░
    */
    
    /* 
    Fᴜɴᴄᴛɪᴏɴ sᴛᴀʀᴛʟᴏᴛᴛᴇʀʏ
        
    Can be launched by the Owner Address only.
    Allows the Owner to start the Lottery.
    */
    function StartLottery() public 
    onlyBy(owner)
    {
        require(lottery_state == LOTTERY_STATE.CLOSED, "can't start a new lottery yet");
        lottery_state = LOTTERY_STATE.OPEN;
        WithdrawOwner = WITHDRAWOWNER.CLOSED;
        Refund = REFUND.CLOSED;
        WithdrawNFT = WITHDRAWNFT.CLOSED;
        OwnerOfTheNFT[1] = owner;
        emit startLottery(msg.sender);
    }
    
    /* 
    
    Ｅｎｄｉｎｇ Ｐｏｓｓｉｂｉｌｉｔｉｅｓ

    As explained in our Medium article, 2 situations are possible:
        1) The target has been reached, so we have the possibility to close the lottery.
            The winner is randomly picked and the NFT is transferred to the winner
        2) The lottery has not reached its target, the lottery is canceled, and allows the participants to get a refund. 
            Also, the NFT is returned to the owner.
    */

    // Ｆｉｒｓｔ Ｓｉｔｕａｔｉｏｎ : The target has veen reached, the lottery will happen 
    function CloseLottery () public 
    onlyBy(owner) 
    {
        require(lottery_state == LOTTERY_STATE.OPEN, "The lottery hasn't even started!");
        require( mul(totalTicketsSales,MINIMUM) > TARGET, "Not enough players to choose a winner");
        lottery_state = LOTTERY_STATE.CALCULATING_WINNER;
        pickWinner();
        WithdrawOwner = WITHDRAWOWNER.OPEN;
        Refund = REFUND.CLOSED;
        WithdrawNFT = WITHDRAWNFT.OPEN;
        emit CloseLotteryAndPickWinner (msg.sender);
    } 

    // Ｓｅｃｏｎｄ Ｓｉｔｕａｔｉｏｎ : The target has not been reached, the lottery is canceled
    function CancelLottery () public
    onlyBy(owner)
    {
        require(lottery_state == LOTTERY_STATE.OPEN, "The lottery hasn't even started!");
        require( mul(totalTicketsSales,MINIMUM) < TARGET, "Enough players to choose a winner");
        WithdrawOwner = WITHDRAWOWNER.CLOSED;
        Refund = REFUND.OPEN;
        WithdrawNFT = WITHDRAWNFT.OPEN;
        emit CancelLotteryAndRefund (msg.sender);
    }

    /*
    
    █░█░█ █ ▀█▀ █░█ █▀▄ █▀█ ▄▀█ █░█░█
    ▀▄▀▄▀ █ ░█░ █▀█ █▄▀ █▀▄ █▀█ ▀▄▀▄▀
    */
    
    /* The  OwnerWithdraw allows the owner to withdraw the amount of ETH deposited by the participants.
        This function is usable ONLY if the target has been reached (the lottery is maintained)
    */
    function  OwnerWithdraw(uint256 amount) public payable
    onlyBy(owner)
    {
		require(WithdrawOwner == WITHDRAWOWNER.OPEN, "Owner can't withdraw");
        pendingWithdrawals[owner] -= amount;
        (bool success, ) = owner.call{value:amount}("");
        require(success);
        emit Withdraw(msg.sender, amount);
	}
	
    /* The GetRefund allows the participants to get a refund.
        This function is usable ONLY if the target has not been reached (the lottery is canceled)
    */
	function GetRefund() public payable reentrancyGuard {
    
        require(Refund == REFUND.OPEN, "Owner can't withdraw");
        uint amount = pendingWithdrawals[msg.sender]; 
        pendingWithdrawals[msg.sender] = 0;
        pendingWithdrawals[owner] -= amount;
        (bool success, ) = msg.sender.call{value:amount}("");
        require(success);
        emit Withdraw(msg.sender, amount);
    }

    /*
    
    █▄░█ █▀▀ ▀█▀
    █░▀█ █▀░ ░█░
    
        █▀█ ▄▀█ █▀█ ▀█▀
        █▀▀ █▀█ █▀▄ ░█░

    */

    // The NFT (BAYC) will be transferred to the winner.
    function GiveNFT(uint256 _NFTId) external 
    onlyBy(owner)
    {
        require(WithdrawNFT == WITHDRAWNFT.OPEN, "You aren't at that stage yet!");
        NFTCore.transferFrom(address(this), OwnerOfTheNFT[1], _NFTId);
        emit NFTGiven(_NFTId);
    }

    /*  
        █▀▀ █░█ ▄▀█ █ █▄░█ █░░ █ █▄░█ █▄▀
        █▄▄ █▀█ █▀█ █ █░▀█ █▄▄ █ █░▀█ █░█
    
    Chainlink VRF Tools to generate random number with on-chain verification of randomness
    More informations : https://docs.chain.link/docs/chainlink-vrf/

    */
    
    // The fonction called by CloseLottery to begin the selection of the winner
    function pickWinner() private {
        require(lottery_state == LOTTERY_STATE.CALCULATING_WINNER, "You aren't at that stage yet!");
        getRandom(lotteryId, lotteryId);
    }

    // To get a random number to Chainlink
    function getRandom(uint256 userProvidedSeed, uint256 lotteryId) public {
        require(lottery_state == LOTTERY_STATE.CALCULATING_WINNER, "You aren't at that stage yet!");
        require(LINK.balanceOf(address(this)) > fee, "Not enough LINK - fill contract with faucet");
        bytes32 _requestId = requestRandomness(keyHash, fee);
        requestIds[_requestId] = lotteryId;
    }

    // Called by the VRF Coordinator to ful fill the random number
    function fulfillRandomness(bytes32 requestId, uint256 randomness) internal override {
        require(lottery_state == LOTTERY_STATE.CALCULATING_WINNER, "You aren't at that stage yet!");
        require(msg.sender == vrfCoordinator, "Fulillment only permitted by Coordinator");
        most_recent_random = randomness;
        uint lotteryId = requestIds[requestId];
        randomNumber[lotteryId] = randomness;
        fulfill_random(randomness);
    }

    // To ful fill the randomness to choose the winner[1] and set the owner of the NFT to the winner
    function fulfill_random(uint256 randomness) internal {
        require(lottery_state == LOTTERY_STATE.CALCULATING_WINNER, "You aren't at that stage yet!");
        require(randomness > 0, "random-not-found");
        uint256 index = randomness % totalTicketsSales;
        address winner = ticketIndex[index];
        lottery_state = LOTTERY_STATE.CLOSED;
        winners[1] = address (winner);
        OwnerOfTheNFT[1] = address (winner);
    }

    /*
    
        █░█ ▀█▀ █ █░░ █ ▀█▀ █▄█
        █▄█ ░█░ █ █▄▄ █ ░█░ ░█░
    */

    // To avoid reentrancy
    modifier reentrancyGuard {
        if (reentrancyLock) {
            revert();
        }
        reentrancyLock = true;
        _;
        reentrancyLock = false;
    }

    // SafeMath library multiplication
    function mul(uint256 a, uint256 b) internal pure returns (uint256 c) {
        if (a == 0) {
            return 0;
        }
        c = a * b;
        require(c / a == b);
        return c;
    }

    // SafeMath library division
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b > 0, "SafeMath: division by zero");
        uint256 c = a / b;    
        return c;
    
    }
    
}
// File: @chainlink/contracts/src/v0.6/VRFConsumerBase.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.6.0;

import "./vendor/SafeMathChainlink.sol";

import "./interfaces/LinkTokenInterface.sol";

import "./VRFRequestIDBase.sol";

/** ****************************************************************************
 * @notice Interface for contracts using VRF randomness
 * *****************************************************************************
 * @dev PURPOSE
 *
 * @dev Reggie the Random Oracle (not his real job) wants to provide randomness
 * @dev to Vera the verifier in such a way that Vera can be sure he's not
 * @dev making his output up to suit himself. Reggie provides Vera a public key
 * @dev to which he knows the secret key. Each time Vera provides a seed to
 * @dev Reggie, he gives back a value which is computed completely
 * @dev deterministically from the seed and the secret key.
 *
 * @dev Reggie provides a proof by which Vera can verify that the output was
 * @dev correctly computed once Reggie tells it to her, but without that proof,
 * @dev the output is indistinguishable to her from a uniform random sample
 * @dev from the output space.
 *
 * @dev The purpose of this contract is to make it easy for unrelated contracts
 * @dev to talk to Vera the verifier about the work Reggie is doing, to provide
 * @dev simple access to a verifiable source of randomness.
 * *****************************************************************************
 * @dev USAGE
 *
 * @dev Calling contracts must inherit from VRFConsumerBase, and can
 * @dev initialize VRFConsumerBase's attributes in their constructor as
 * @dev shown:
 *
 * @dev   contract VRFConsumer {
 * @dev     constuctor(<other arguments>, address _vrfCoordinator, address _link)
 * @dev       VRFConsumerBase(_vrfCoordinator, _link) public {
 * @dev         <initialization with other arguments goes here>
 * @dev       }
 * @dev   }
 *
 * @dev The oracle will have given you an ID for the VRF keypair they have
 * @dev committed to (let's call it keyHash), and have told you the minimum LINK
 * @dev price for VRF service. Make sure your contract has sufficient LINK, and
 * @dev call requestRandomness(keyHash, fee, seed), where seed is the input you
 * @dev want to generate randomness from.
 *
 * @dev Once the VRFCoordinator has received and validated the oracle's response
 * @dev to your request, it will call your contract's fulfillRandomness method.
 *
 * @dev The randomness argument to fulfillRandomness is the actual random value
 * @dev generated from your seed.
 *
 * @dev The requestId argument is generated from the keyHash and the seed by
 * @dev makeRequestId(keyHash, seed). If your contract could have concurrent
 * @dev requests open, you can use the requestId to track which seed is
 * @dev associated with which randomness. See VRFRequestIDBase.sol for more
 * @dev details. (See "SECURITY CONSIDERATIONS" for principles to keep in mind,
 * @dev if your contract could have multiple requests in flight simultaneously.)
 *
 * @dev Colliding `requestId`s are cryptographically impossible as long as seeds
 * @dev differ. (Which is critical to making unpredictable randomness! See the
 * @dev next section.)
 *
 * *****************************************************************************
 * @dev SECURITY CONSIDERATIONS
 *
 * @dev A method with the ability to call your fulfillRandomness method directly
 * @dev could spoof a VRF response with any random value, so it's critical that
 * @dev it cannot be directly called by anything other than this base contract
 * @dev (specifically, by the VRFConsumerBase.rawFulfillRandomness method).
 *
 * @dev For your users to trust that your contract's random behavior is free
 * @dev from malicious interference, it's best if you can write it so that all
 * @dev behaviors implied by a VRF response are executed *during* your
 * @dev fulfillRandomness method. If your contract must store the response (or
 * @dev anything derived from it) and use it later, you must ensure that any
 * @dev user-significant behavior which depends on that stored value cannot be
 * @dev manipulated by a subsequent VRF request.
 *
 * @dev Similarly, both miners and the VRF oracle itself have some influence
 * @dev over the order in which VRF responses appear on the blockchain, so if
 * @dev your contract could have multiple VRF requests in flight simultaneously,
 * @dev you must ensure that the order in which the VRF responses arrive cannot
 * @dev be used to manipulate your contract's user-significant behavior.
 *
 * @dev Since the ultimate input to the VRF is mixed with the block hash of the
 * @dev block in which the request is made, user-provided seeds have no impact
 * @dev on its economic security properties. They are only included for API
 * @dev compatability with previous versions of this contract.
 *
 * @dev Since the block hash of the block which contains the requestRandomness
 * @dev call is mixed into the input to the VRF *last*, a sufficiently powerful
 * @dev miner could, in principle, fork the blockchain to evict the block
 * @dev containing the request, forcing the request to be included in a
 * @dev different block with a different hash, and therefore a different input
 * @dev to the VRF. However, such an attack would incur a substantial economic
 * @dev cost. This cost scales with the number of blocks the VRF oracle waits
 * @dev until it calls responds to a request.
 */
abstract contract VRFConsumerBase is VRFRequestIDBase {

  using SafeMathChainlink for uint256;

  /**
   * @notice fulfillRandomness handles the VRF response. Your contract must
   * @notice implement it. See "SECURITY CONSIDERATIONS" above for important
   * @notice principles to keep in mind when implementing your fulfillRandomness
   * @notice method.
   *
   * @dev VRFConsumerBase expects its subcontracts to have a method with this
   * @dev signature, and will call it once it has verified the proof
   * @dev associated with the randomness. (It is triggered via a call to
   * @dev rawFulfillRandomness, below.)
   *
   * @param requestId The Id initially returned by requestRandomness
   * @param randomness the VRF output
   */
  function fulfillRandomness(bytes32 requestId, uint256 randomness)
    internal virtual;

  /**
   * @dev In order to keep backwards compatibility we have kept the user
   * seed field around. We remove the use of it because given that the blockhash
   * enters later, it overrides whatever randomness the used seed provides.
   * Given that it adds no security, and can easily lead to misunderstandings,
   * we have removed it from usage and can now provide a simpler API.
   */
  uint256 constant private USER_SEED_PLACEHOLDER = 0;

  /**
   * @notice requestRandomness initiates a request for VRF output given _seed
   *
   * @dev The fulfillRandomness method receives the output, once it's provided
   * @dev by the Oracle, and verified by the vrfCoordinator.
   *
   * @dev The _keyHash must already be registered with the VRFCoordinator, and
   * @dev the _fee must exceed the fee specified during registration of the
   * @dev _keyHash.
   *
   * @dev The _seed parameter is vestigial, and is kept only for API
   * @dev compatibility with older versions. It can't *hurt* to mix in some of
   * @dev your own randomness, here, but it's not necessary because the VRF
   * @dev oracle will mix the hash of the block containing your request into the
   * @dev VRF seed it ultimately uses.
   *
   * @param _keyHash ID of public key against which randomness is generated
   * @param _fee The amount of LINK to send with the request
   *
   * @return requestId unique ID for this request
   *
   * @dev The returned requestId can be used to distinguish responses to
   * @dev concurrent requests. It is passed as the first argument to
   * @dev fulfillRandomness.
   */
  function requestRandomness(bytes32 _keyHash, uint256 _fee)
    internal returns (bytes32 requestId)
  {
    LINK.transferAndCall(vrfCoordinator, _fee, abi.encode(_keyHash, USER_SEED_PLACEHOLDER));
    // This is the seed passed to VRFCoordinator. The oracle will mix this with
    // the hash of the block containing this request to obtain the seed/input
    // which is finally passed to the VRF cryptographic machinery.
    uint256 vRFSeed  = makeVRFInputSeed(_keyHash, USER_SEED_PLACEHOLDER, address(this), nonces[_keyHash]);
    // nonces[_keyHash] must stay in sync with
    // VRFCoordinator.nonces[_keyHash][this], which was incremented by the above
    // successful LINK.transferAndCall (in VRFCoordinator.randomnessRequest).
    // This provides protection against the user repeating their input seed,
    // which would result in a predictable/duplicate output, if multiple such
    // requests appeared in the same block.
    nonces[_keyHash] = nonces[_keyHash].add(1);
    return makeRequestId(_keyHash, vRFSeed);
  }

  LinkTokenInterface immutable internal LINK;
  address immutable private vrfCoordinator;

  // Nonces for each VRF key from which randomness has been requested.
  //
  // Must stay in sync with VRFCoordinator[_keyHash][this]
  mapping(bytes32 /* keyHash */ => uint256 /* nonce */) private nonces;

  /**
   * @param _vrfCoordinator address of VRFCoordinator contract
   * @param _link address of LINK token contract
   *
   * @dev https://docs.chain.link/docs/link-token-contracts
   */
  constructor(address _vrfCoordinator, address _link) public {
    vrfCoordinator = _vrfCoordinator;
    LINK = LinkTokenInterface(_link);
  }

  // rawFulfillRandomness is called by VRFCoordinator when it receives a valid VRF
  // proof. rawFulfillRandomness then calls fulfillRandomness, after validating
  // the origin of the call
  function rawFulfillRandomness(bytes32 requestId, uint256 randomness) external {
    require(msg.sender == vrfCoordinator, "Only VRFCoordinator can fulfill");
    fulfillRandomness(requestId, randomness);
  }
}

// File: @chainlink/contracts/src/v0.6/ChainlinkClient.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.6.0;

import "./Chainlink.sol";
import "./interfaces/ENSInterface.sol";
import "./interfaces/LinkTokenInterface.sol";
import "./interfaces/ChainlinkRequestInterface.sol";
import "./interfaces/PointerInterface.sol";
import { ENSResolver as ENSResolver_Chainlink } from "./vendor/ENSResolver.sol";

/**
 * @title The ChainlinkClient contract
 * @notice Contract writers can inherit this contract in order to create requests for the
 * Chainlink network
 */
contract ChainlinkClient {
  using Chainlink for Chainlink.Request;

  uint256 constant internal LINK = 10**18;
  uint256 constant private AMOUNT_OVERRIDE = 0;
  address constant private SENDER_OVERRIDE = address(0);
  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 requestCount = 1;
  mapping(bytes32 => address) private pendingRequests;

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

  /**
   * @notice Creates a request that can hold additional parameters
   * @param _specId The Job Specification ID that the request will be created for
   * @param _callbackAddress The callback address that the response will be sent to
   * @param _callbackFunctionSignature The callback function signature to use for the callback address
   * @return A Chainlink Request struct in memory
   */
  function buildChainlinkRequest(
    bytes32 _specId,
    address _callbackAddress,
    bytes4 _callbackFunctionSignature
  ) internal pure returns (Chainlink.Request memory) {
    Chainlink.Request memory req;
    return req.initialize(_specId, _callbackAddress, _callbackFunctionSignature);
  }

  /**
   * @notice Creates a Chainlink request to the stored oracle address
   * @dev Calls `chainlinkRequestTo` with the stored oracle address
   * @param _req The initialized Chainlink Request
   * @param _payment The amount of LINK to send for the request
   * @return requestId The request ID
   */
  function sendChainlinkRequest(Chainlink.Request memory _req, uint256 _payment)
    internal
    returns (bytes32)
  {
    return sendChainlinkRequestTo(address(oracle), _req, _payment);
  }

  /**
   * @notice Creates a Chainlink request to the specified oracle address
   * @dev Generates and stores a request ID, increments the local nonce, and uses `transferAndCall` to
   * send LINK which creates a request on the target oracle contract.
   * Emits ChainlinkRequested event.
   * @param _oracle The address of the oracle for the request
   * @param _req The initialized Chainlink Request
   * @param _payment The amount of LINK to send for the request
   * @return requestId The request ID
   */
  function sendChainlinkRequestTo(address _oracle, Chainlink.Request memory _req, uint256 _payment)
    internal
    returns (bytes32 requestId)
  {
    requestId = keccak256(abi.encodePacked(this, requestCount));
    _req.nonce = requestCount;
    pendingRequests[requestId] = _oracle;
    emit ChainlinkRequested(requestId);
    require(link.transferAndCall(_oracle, _payment, encodeRequest(_req)), "unable to transferAndCall to oracle");
    requestCount += 1;

    return requestId;
  }

  /**
   * @notice Allows a request to be cancelled if it has not been fulfilled
   * @dev Requires keeping track of the expiration value emitted from the oracle contract.
   * Deletes the request from the `pendingRequests` mapping.
   * Emits ChainlinkCancelled event.
   * @param _requestId The request ID
   * @param _payment The amount of LINK sent for the request
   * @param _callbackFunc The callback function specified for the request
   * @param _expiration The time of the expiration for the request
   */
  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);
  }

  /**
   * @notice Sets the stored oracle address
   * @param _oracle The address of the oracle contract
   */
  function setChainlinkOracle(address _oracle) internal {
    oracle = ChainlinkRequestInterface(_oracle);
  }

  /**
   * @notice Sets the LINK token address
   * @param _link The address of the LINK token contract
   */
  function setChainlinkToken(address _link) internal {
    link = LinkTokenInterface(_link);
  }

  /**
   * @notice Sets the Chainlink token address for the public
   * network as given by the Pointer contract
   */
  function setPublicChainlinkToken() internal {
    setChainlinkToken(PointerInterface(LINK_TOKEN_POINTER).getAddress());
  }

  /**
   * @notice Retrieves the stored address of the LINK token
   * @return The address of the LINK token
   */
  function chainlinkTokenAddress()
    internal
    view
    returns (address)
  {
    return address(link);
  }

  /**
   * @notice Retrieves the stored address of the oracle contract
   * @return The address of the oracle contract
   */
  function chainlinkOracleAddress()
    internal
    view
    returns (address)
  {
    return address(oracle);
  }

  /**
   * @notice Allows for a request which was created on another contract to be fulfilled
   * on this contract
   * @param _oracle The address of the oracle contract that will fulfill the request
   * @param _requestId The request ID used for the response
   */
  function addChainlinkExternalRequest(address _oracle, bytes32 _requestId)
    internal
    notPendingRequest(_requestId)
  {
    pendingRequests[_requestId] = _oracle;
  }

  /**
   * @notice Sets the stored oracle and LINK token contracts with the addresses resolved by ENS
   * @dev Accounts for subnodes having different resolvers
   * @param _ens The address of the ENS contract
   * @param _node The ENS node hash
   */
  function useChainlinkWithENS(address _ens, bytes32 _node)
    internal
  {
    ens = ENSInterface(_ens);
    ensNode = _node;
    bytes32 linkSubnode = keccak256(abi.encodePacked(ensNode, ENS_TOKEN_SUBNAME));
    ENSResolver_Chainlink resolver = ENSResolver_Chainlink(ens.resolver(linkSubnode));
    setChainlinkToken(resolver.addr(linkSubnode));
    updateChainlinkOracleWithENS();
  }

  /**
   * @notice Sets the stored oracle contract with the address resolved by ENS
   * @dev This may be called on its own as long as `useChainlinkWithENS` has been called previously
   */
  function updateChainlinkOracleWithENS()
    internal
  {
    bytes32 oracleSubnode = keccak256(abi.encodePacked(ensNode, ENS_ORACLE_SUBNAME));
    ENSResolver_Chainlink resolver = ENSResolver_Chainlink(ens.resolver(oracleSubnode));
    setChainlinkOracle(resolver.addr(oracleSubnode));
  }

  /**
   * @notice Encodes the request to be sent to the oracle contract
   * @dev The Chainlink node expects values to be in order for the request to be picked up. Order of types
   * will be validated in the oracle contract.
   * @param _req The initialized Chainlink Request
   * @return The bytes payload for the `transferAndCall` method
   */
  function encodeRequest(Chainlink.Request memory _req)
    private
    view
    returns (bytes memory)
  {
    return abi.encodeWithSelector(
      oracle.oracleRequest.selector,
      SENDER_OVERRIDE, // Sender value - overridden by onTokenTransfer by the requesting contract's address
      AMOUNT_OVERRIDE, // Amount value - overridden by onTokenTransfer by the actual amount of LINK sent
      _req.id,
      _req.callbackAddress,
      _req.callbackFunctionId,
      _req.nonce,
      ARGS_VERSION,
      _req.buf.buf);
  }

  /**
   * @notice Ensures that the fulfillment is valid for this contract
   * @dev Use if the contract developer prefers methods instead of modifiers for validation
   * @param _requestId The request ID for fulfillment
   */
  function validateChainlinkCallback(bytes32 _requestId)
    internal
    recordChainlinkFulfillment(_requestId)
    // solhint-disable-next-line no-empty-blocks
  {}

  /**
   * @dev Reverts if the sender is not the oracle of the request.
   * Emits ChainlinkFulfilled event.
   * @param _requestId The request ID for fulfillment
   */
  modifier recordChainlinkFulfillment(bytes32 _requestId) {
    require(msg.sender == pendingRequests[_requestId],
            "Source must be the oracle of the request");
    delete pendingRequests[_requestId];
    emit ChainlinkFulfilled(_requestId);
    _;
  }

  /**
   * @dev Reverts if the request is already pending
   * @param _requestId The request ID for fulfillment
   */
  modifier notPendingRequest(bytes32 _requestId) {
    require(pendingRequests[_requestId] == address(0), "Request is already pending");
    _;
  }
}

// File: @chainlink/contracts/src/v0.6/VRFRequestIDBase.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.6.0;

contract VRFRequestIDBase {

  /**
   * @notice returns the seed which is actually input to the VRF coordinator
   *
   * @dev To prevent repetition of VRF output due to repetition of the
   * @dev user-supplied seed, that seed is combined in a hash with the
   * @dev user-specific nonce, and the address of the consuming contract. The
   * @dev risk of repetition is mostly mitigated by inclusion of a blockhash in
   * @dev the final seed, but the nonce does protect against repetition in
   * @dev requests which are included in a single block.
   *
   * @param _userSeed VRF seed input provided by user
   * @param _requester Address of the requesting contract
   * @param _nonce User-specific nonce at the time of the request
   */
  function makeVRFInputSeed(bytes32 _keyHash, uint256 _userSeed,
    address _requester, uint256 _nonce)
    internal pure returns (uint256)
  {
    return  uint256(keccak256(abi.encode(_keyHash, _userSeed, _requester, _nonce)));
  }

  /**
   * @notice Returns the id for this request
   * @param _keyHash The serviceAgreement ID to be used for this request
   * @param _vRFInputSeed The seed to be passed directly to the VRF
   * @return The id for this request
   *
   * @dev Note that _vRFInputSeed is not the seed passed by the consuming
   * @dev contract, but the one generated by makeVRFInputSeed
   */
  function makeRequestId(
    bytes32 _keyHash, uint256 _vRFInputSeed) internal pure returns (bytes32) {
    return keccak256(abi.encodePacked(_keyHash, _vRFInputSeed));
  }
}

// File: @chainlink/contracts/src/v0.6/interfaces/LinkTokenInterface.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.6.0;

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

// File: @chainlink/contracts/src/v0.6/vendor/SafeMathChainlink.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.6.0;

/**
 * @dev Wrappers over Solidity's arithmetic operations with added overflow
 * checks.
 *
 * Arithmetic operations in Solidity wrap on overflow. This can easily result
 * in bugs, because programmers usually assume that an overflow raises an
 * error, which is the standard behavior in high level programming languages.
 * `SafeMath` restores this intuition by reverting the transaction when an
 * operation overflows.
 *
 * Using this library instead of the unchecked operations eliminates an entire
 * class of bugs, so it's recommended to use it always.
 */
library SafeMathChainlink {
  /**
    * @dev Returns the addition of two unsigned integers, reverting on
    * overflow.
    *
    * Counterpart to Solidity's `+` operator.
    *
    * Requirements:
    * - Addition cannot overflow.
    */
  function add(uint256 a, uint256 b) internal pure returns (uint256) {
    uint256 c = a + b;
    require(c >= a, "SafeMath: addition overflow");

    return c;
  }

  /**
    * @dev Returns the subtraction of two unsigned integers, reverting on
    * overflow (when the result is negative).
    *
    * Counterpart to Solidity's `-` operator.
    *
    * Requirements:
    * - Subtraction cannot overflow.
    */
  function sub(uint256 a, uint256 b) internal pure returns (uint256) {
    require(b <= a, "SafeMath: subtraction overflow");
    uint256 c = a - b;

    return c;
  }

  /**
    * @dev Returns the multiplication of two unsigned integers, reverting on
    * overflow.
    *
    * Counterpart to Solidity's `*` operator.
    *
    * Requirements:
    * - Multiplication cannot overflow.
    */
  function mul(uint256 a, uint256 b) internal pure returns (uint256) {
    // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
    // benefit is lost if 'b' is also tested.
    // See: https://github.com/OpenZeppelin/openzeppelin-solidity/pull/522
    if (a == 0) {
      return 0;
    }

    uint256 c = a * b;
    require(c / a == b, "SafeMath: multiplication overflow");

    return c;
  }

  /**
    * @dev Returns the integer division of two unsigned integers. Reverts on
    * division by zero. The result is rounded towards zero.
    *
    * Counterpart to Solidity's `/` operator. Note: this function uses a
    * `revert` opcode (which leaves remaining gas untouched) while Solidity
    * uses an invalid opcode to revert (consuming all remaining gas).
    *
    * Requirements:
    * - The divisor cannot be zero.
    */
  function div(uint256 a, uint256 b) internal pure returns (uint256) {
    // Solidity only automatically asserts when dividing by 0
    require(b > 0, "SafeMath: division by zero");
    uint256 c = a / b;
    // assert(a == b * c + a % b); // There is no case in which this doesn't hold

    return c;
  }

  /**
    * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
    * Reverts when dividing by zero.
    *
    * Counterpart to Solidity's `%` operator. This function uses a `revert`
    * opcode (which leaves remaining gas untouched) while Solidity uses an
    * invalid opcode to revert (consuming all remaining gas).
    *
    * Requirements:
    * - The divisor cannot be zero.
    */
  function mod(uint256 a, uint256 b) internal pure returns (uint256) {
    require(b != 0, "SafeMath: modulo by zero");
    return a % b;
  }
}

// File: @chainlink/contracts/src/v0.6/vendor/ENSResolver.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.6.0;

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

// File: @chainlink/contracts/src/v0.6/interfaces/PointerInterface.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.6.0;

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

// File: @chainlink/contracts/src/v0.6/interfaces/ChainlinkRequestInterface.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.6.0;

interface ChainlinkRequestInterface {
  function oracleRequest(
    address sender,
    uint256 requestPrice,
    bytes32 serviceAgreementID,
    address callbackAddress,
    bytes4 callbackFunctionId,
    uint256 nonce,
    uint256 dataVersion,
    bytes calldata data
  ) external;

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

// File: @chainlink/contracts/src/v0.6/interfaces/ENSInterface.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.6.0;

interface ENSInterface {

  // Logged when the owner of a node assigns a new owner to a subnode.
  event NewOwner(bytes32 indexed node, bytes32 indexed label, address owner);

  // Logged when the owner of a node transfers ownership to a new account.
  event Transfer(bytes32 indexed node, address owner);

  // Logged when the resolver for a node changes.
  event NewResolver(bytes32 indexed node, address resolver);

  // Logged when the TTL of a node changes
  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);

}

// File: @chainlink/contracts/src/v0.6/Chainlink.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.6.0;

import { CBORChainlink } from "./vendor/CBORChainlink.sol";
import { BufferChainlink } from "./vendor/BufferChainlink.sol";

/**
 * @title Library for common Chainlink functions
 * @dev Uses imported CBOR library for encoding to buffer
 */
library Chainlink {
  uint256 internal constant defaultBufferSize = 256; // solhint-disable-line const-name-snakecase

  using CBORChainlink for BufferChainlink.buffer;

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

  /**
   * @notice Initializes a Chainlink request
   * @dev Sets the ID, callback address, and callback function signature on the request
   * @param self The uninitialized request
   * @param _id The Job Specification ID
   * @param _callbackAddress The callback address
   * @param _callbackFunction The callback function signature
   * @return The initialized request
   */
  function initialize(
    Request memory self,
    bytes32 _id,
    address _callbackAddress,
    bytes4 _callbackFunction
  ) internal pure returns (Chainlink.Request memory) {
    BufferChainlink.init(self.buf, defaultBufferSize);
    self.id = _id;
    self.callbackAddress = _callbackAddress;
    self.callbackFunctionId = _callbackFunction;
    return self;
  }

  /**
   * @notice Sets the data for the buffer without encoding CBOR on-chain
   * @dev CBOR can be closed with curly-brackets {} or they can be left off
   * @param self The initialized request
   * @param _data The CBOR data
   */
  function setBuffer(Request memory self, bytes memory _data)
    internal pure
  {
    BufferChainlink.init(self.buf, _data.length);
    BufferChainlink.append(self.buf, _data);
  }

  /**
   * @notice Adds a string value to the request with a given key name
   * @param self The initialized request
   * @param _key The name of the key
   * @param _value The string value to add
   */
  function add(Request memory self, string memory _key, string memory _value)
    internal pure
  {
    self.buf.encodeString(_key);
    self.buf.encodeString(_value);
  }

  /**
   * @notice Adds a bytes value to the request with a given key name
   * @param self The initialized request
   * @param _key The name of the key
   * @param _value The bytes value to add
   */
  function addBytes(Request memory self, string memory _key, bytes memory _value)
    internal pure
  {
    self.buf.encodeString(_key);
    self.buf.encodeBytes(_value);
  }

  /**
   * @notice Adds a int256 value to the request with a given key name
   * @param self The initialized request
   * @param _key The name of the key
   * @param _value The int256 value to add
   */
  function addInt(Request memory self, string memory _key, int256 _value)
    internal pure
  {
    self.buf.encodeString(_key);
    self.buf.encodeInt(_value);
  }

  /**
   * @notice Adds a uint256 value to the request with a given key name
   * @param self The initialized request
   * @param _key The name of the key
   * @param _value The uint256 value to add
   */
  function addUint(Request memory self, string memory _key, uint256 _value)
    internal pure
  {
    self.buf.encodeString(_key);
    self.buf.encodeUInt(_value);
  }

  /**
   * @notice Adds an array of strings to the request with a given key name
   * @param self The initialized request
   * @param _key The name of the key
   * @param _values The array of string values to add
   */
  function addStringArray(Request memory self, string memory _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();
  }
}

// File: @chainlink/contracts/src/v0.6/vendor/BufferChainlink.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.6.0;

/**
* @dev A library for working with mutable byte buffers in Solidity.
*
* Byte buffers are mutable and expandable, and provide a variety of primitives
* for writing to them. At any time you can fetch a bytes object containing the
* current contents of the buffer. The bytes object should not be stored between
* operations, as it may change due to resizing of the buffer.
*/
library BufferChainlink {
  /**
  * @dev Represents a mutable buffer. Buffers have a current value (buf) and
  *      a capacity. The capacity may be longer than the current value, in
  *      which case it can be extended without the need to allocate more memory.
  */
  struct buffer {
    bytes buf;
    uint capacity;
  }

  /**
  * @dev Initializes a buffer with an initial capacity.
  * @param buf The buffer to initialize.
  * @param capacity The number of bytes of space to allocate the buffer.
  * @return The buffer, for chaining.
  */
  function init(buffer memory buf, uint capacity) internal pure returns(buffer memory) {
    if (capacity % 32 != 0) {
      capacity += 32 - (capacity % 32);
    }
    // Allocate space for the buffer data
    buf.capacity = capacity;
    assembly {
      let ptr := mload(0x40)
      mstore(buf, ptr)
      mstore(ptr, 0)
      mstore(0x40, add(32, add(ptr, capacity)))
    }
    return buf;
  }

  /**
  * @dev Initializes a new buffer from an existing bytes object.
  *      Changes to the buffer may mutate the original value.
  * @param b The bytes object to initialize the buffer with.
  * @return A new buffer.
  */
  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;
  }

  /**
  * @dev Sets buffer length to 0.
  * @param buf The buffer to truncate.
  * @return The original buffer, for chaining..
  */
  function truncate(buffer memory buf) internal pure returns (buffer memory) {
    assembly {
      let bufptr := mload(buf)
      mstore(bufptr, 0)
    }
    return buf;
  }

  /**
  * @dev Writes a byte string to a buffer. Resizes if doing so would exceed
  *      the capacity of the buffer.
  * @param buf The buffer to append to.
  * @param off The start offset to write to.
  * @param data The data to append.
  * @param len The number of bytes to copy.
  * @return The original buffer, for chaining.
  */
  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 {
      // Memory address of the buffer data
      let bufptr := mload(buf)
      // Length of existing buffer data
      let buflen := mload(bufptr)
      // Start address = buffer address + offset + sizeof(buffer length)
      dest := add(add(bufptr, 32), off)
      // Update buffer length if we're extending it
      if gt(add(len, off), buflen) {
        mstore(bufptr, add(len, off))
      }
      src := add(data, 32)
    }

    // Copy word-length chunks while possible
    for (; len >= 32; len -= 32) {
      assembly {
        mstore(dest, mload(src))
      }
      dest += 32;
      src += 32;
    }

    // Copy 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))
    }

    return buf;
  }

  /**
  * @dev Appends a byte string to a buffer. Resizes if doing so would exceed
  *      the capacity of the buffer.
  * @param buf The buffer to append to.
  * @param data The data to append.
  * @param len The number of bytes to copy.
  * @return The original buffer, for chaining.
  */
  function append(buffer memory buf, bytes memory data, uint len) internal pure returns (buffer memory) {
    return write(buf, buf.buf.length, data, len);
  }

  /**
  * @dev Appends a byte string to a buffer. Resizes if doing so would exceed
  *      the capacity of the buffer.
  * @param buf The buffer to append to.
  * @param data The data to append.
  * @return The original buffer, for chaining.
  */
  function append(buffer memory buf, bytes memory data) internal pure returns (buffer memory) {
    return write(buf, buf.buf.length, data, data.length);
  }

  /**
  * @dev Writes a byte to the buffer. Resizes if doing so would exceed the
  *      capacity of the buffer.
  * @param buf The buffer to append to.
  * @param off The offset to write the byte at.
  * @param data The data to append.
  * @return The original buffer, for chaining.
  */
  function writeUint8(buffer memory buf, uint off, uint8 data) internal pure returns(buffer memory) {
    if (off >= buf.capacity) {
      resize(buf, buf.capacity * 2);
    }

    assembly {
      // Memory address of the buffer data
      let bufptr := mload(buf)
      // Length of existing buffer data
      let buflen := mload(bufptr)
      // Address = buffer address + sizeof(buffer length) + off
      let dest := add(add(bufptr, off), 32)
      mstore8(dest, data)
      // Update buffer length if we extended it
      if eq(off, buflen) {
        mstore(bufptr, add(buflen, 1))
      }
    }
    return buf;
  }

  /**
  * @dev Appends a byte to the buffer. Resizes if doing so would exceed the
  *      capacity of the buffer.
  * @param buf The buffer to append to.
  * @param data The data to append.
  * @return The original buffer, for chaining.
  */
  function appendUint8(buffer memory buf, uint8 data) internal pure returns(buffer memory) {
    return writeUint8(buf, buf.buf.length, data);
  }

  /**
  * @dev Writes up to 32 bytes to the buffer. Resizes if doing so would
  *      exceed the capacity of the buffer.
  * @param buf The buffer to append to.
  * @param off The offset to write at.
  * @param data The data to append.
  * @param len The number of bytes to write (left-aligned).
  * @return The original buffer, for chaining.
  */
  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;
    // Right-align data
    data = data >> (8 * (32 - len));
    assembly {
      // Memory address of the buffer data
      let bufptr := mload(buf)
      // Address = buffer address + sizeof(buffer length) + off + len
      let dest := add(add(bufptr, off), len)
      mstore(dest, or(and(mload(dest), not(mask)), data))
      // Update buffer length if we extended it
      if gt(add(off, len), mload(bufptr)) {
        mstore(bufptr, add(off, len))
      }
    }
    return buf;
  }

  /**
  * @dev Writes a bytes20 to the buffer. Resizes if doing so would exceed the
  *      capacity of the buffer.
  * @param buf The buffer to append to.
  * @param off The offset to write at.
  * @param data The data to append.
  * @return The original buffer, for chaining.
  */
  function writeBytes20(buffer memory buf, uint off, bytes20 data) internal pure returns (buffer memory) {
    return write(buf, off, bytes32(data), 20);
  }

  /**
  * @dev Appends a bytes20 to the buffer. Resizes if doing so would exceed
  *      the capacity of the buffer.
  * @param buf The buffer to append to.
  * @param data The data to append.
  * @return The original buffer, for chhaining.
  */
  function appendBytes20(buffer memory buf, bytes20 data) internal pure returns (buffer memory) {
    return write(buf, buf.buf.length, bytes32(data), 20);
  }

  /**
  * @dev Appends a bytes32 to the buffer. Resizes if doing so would exceed
  *      the capacity of the buffer.
  * @param buf The buffer to append to.
  * @param data The data to append.
  * @return The original buffer, for chaining.
  */
  function appendBytes32(buffer memory buf, bytes32 data) internal pure returns (buffer memory) {
    return write(buf, buf.buf.length, data, 32);
  }

  /**
  * @dev Writes an integer to the buffer. Resizes if doing so would exceed
  *      the capacity of the buffer.
  * @param buf The buffer to append to.
  * @param off The offset to write at.
  * @param data The data to append.
  * @param len The number of bytes to write (right-aligned).
  * @return The original buffer, for chaining.
  */
  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 {
      // Memory address of the buffer data
      let bufptr := mload(buf)
      // Address = buffer address + off + sizeof(buffer length) + len
      let dest := add(add(bufptr, off), len)
      mstore(dest, or(and(mload(dest), not(mask)), data))
      // Update buffer length if we extended it
      if gt(add(off, len), mload(bufptr)) {
        mstore(bufptr, add(off, len))
      }
    }
    return buf;
  }

  /**
    * @dev Appends a byte to the end of the buffer. Resizes if doing so would
    * exceed the capacity of the buffer.
    * @param buf The buffer to append to.
    * @param data The data to append.
    * @return The original buffer.
    */
  function appendInt(buffer memory buf, uint data, uint len) internal pure returns(buffer memory) {
    return writeInt(buf, buf.buf.length, data, len);
  }
}

// File: @chainlink/contracts/src/v0.6/vendor/CBORChainlink.sol



// SPDX-License-Identifier: MIT
pragma solidity >= 0.4.19;

import { BufferChainlink } from "./BufferChainlink.sol";

library CBORChainlink {
  using BufferChainlink for BufferChainlink.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_TAG = 6;
  uint8 private constant MAJOR_TYPE_CONTENT_FREE = 7;

  uint8 private constant TAG_TYPE_BIGNUM = 2;
  uint8 private constant TAG_TYPE_NEGATIVE_BIGNUM = 3;

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

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

  function encodeInt(
    BufferChainlink.buffer memory buf,
    int value
  )
    internal
    pure
  {
    if(value < -0x10000000000000000) {
      encodeSignedBigNum(buf, value);
    } else if(value > 0xFFFFFFFFFFFFFFFF) {
      encodeBigNum(buf, value);
    } else if(value >= 0) {
      encodeType(buf, MAJOR_TYPE_INT, uint(value));
    } else {
      encodeType(buf, MAJOR_TYPE_NEGATIVE_INT, uint(-1 - value));
    }
  }

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

  function encodeBigNum(
    BufferChainlink.buffer memory buf,
    int value
  )
    internal
    pure
  {
    buf.appendUint8(uint8((MAJOR_TYPE_TAG << 5) | TAG_TYPE_BIGNUM));
    encodeBytes(buf, abi.encode(uint(value)));
  }

  function encodeSignedBigNum(
    BufferChainlink.buffer memory buf,
    int input
  )
    internal
    pure
  {
    buf.appendUint8(uint8((MAJOR_TYPE_TAG << 5) | TAG_TYPE_NEGATIVE_BIGNUM));
    encodeBytes(buf, abi.encode(uint(-1 - input)));
  }

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

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

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

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