// File: Squares.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.11;

import "@openzeppelin/contracts/token/ERC721/IERC721.sol";
import "@openzeppelin/contracts/access/Ownable.sol";
import "@openzeppelin/contracts/utils/math/SafeMath.sol";
import "./AdAuction.sol";
import "./SportsDataAPIConsumer.sol";
import "./RandomGameBoard.sol";
import "./SquaresNFT.sol";
import "./Tag.sol";

/** 
  * @author Atlas Corporation
  * @title Squares on Chain
  */
contract Squares is Ownable, SquaresNFT, RandomGameBoard, SportsDataAPIConsumer, AdAuction {

    using SafeMath for uint256;

    mapping(uint256 => bool) public quarterPrizeClaimed;
    uint256 public totalPrizeCollected;

    constructor()
    SportsDataAPIConsumer(0x0aefab6f66d0278B99B6eCbFa8a03f9828cD90b0)
    AdAuction("Atlas Corp",0xe64581F067Cfdce58657E3c0F58175e638C30f2B)
    {
    }

    function getGameBoardRandomness() public override(RandomGameBoard) onlyOwner returns (bytes32) {
        return super.getGameBoardRandomness();
    }

    function assignGameBoard() public override(RandomGameBoard) onlyOwner {
        super.assignGameBoard();
    }

    function getGameScores() public override(SportsDataAPIConsumer) onlyOwner {
        super.getGameScores();
    }

    function getTile(uint256 _homeScore, uint256 _awayScore) public view returns (uint256) {
        require(gameState == GameState.Set, "Game not set");
        require(_homeScore >= 0 && _homeScore <= 9,"Home score must be within the bounds 0 to 9");
        require(_awayScore >= 0 && _awayScore <= 9,"Home score must be within the bounds 0 to 9");
        
        if(teamAssignment){
            return calculateTileNumber(homeTeamMap[_homeScore], awayTeamMap[_awayScore]);
        }
        else{
            return calculateTileNumber(awayTeamMap[_awayScore], homeTeamMap[_homeScore]);
        }
    }

    function calculateTileNumber(uint256 _x, uint256 _y) public pure returns (uint256){
        require(_x >= 0 && _x <= 9, "X out of bounds");
        require(_y >= 0 && _y <= 9, "Y out of bounds");
        return _y.mul(10).add(_x).add(1);
    }

    function getScorePair(uint256 _tokenId) public view returns (uint256 _homeScore, uint256 _awayScore){
        require(gameState == GameState.Set, "Game not set");
        require(_tokenId > 0, "TokenID must be greater than 0");
        require(_tokenId <= 100, "TokenID must be less than 100");

        uint256 x = _tokenId.sub(1).mod(10);
        uint256 y = _tokenId.sub(1).sub(x).div(10);

        if(teamAssignment){
            return (homeTeam[x],awayTeam[y]);
        }
        else{
            return (homeTeam[y],awayTeam[x]);
        }
    }

    function startAdSale() public override(AdAuction) onlyOwner {
        require(gameState != GameState.Complete, "Game is complete. No more ads");
        super.startAdSale();
    }

    function stopAdSale() public override(AdAuction) onlyOwner {
        totalPrizeCollected = address(this).balance;
        super.stopAdSale();
    }

    function claimPrize(uint256 _quarter) public {
        require(_quarter >= 1 && _quarter <= 4, "Quarter must be 1 through 4");
        require(quarter[_quarter].homeDataState == DataState.Complete, "Home Score Not Set");
        require(quarter[_quarter].awayDataState == DataState.Complete, "Away Score Not Set");
        require(!quarterPrizeClaimed[_quarter],"Prize already claimed");
        require(ownerOf(quarterWinner(_quarter))==msg.sender,"Caller does not own winning tile");
        require(!adSaleActive,"Prizes cannot be claimed while Ad Auction is live");
        require(totalPrizeCollected!=0,"No prize pool");
        require(payable(msg.sender).send(totalPrizeCollected.div(4)));
        quarterPrizeClaimed[_quarter] = true;
    }

    function quarterWinner(uint256 _quarter) public view returns (uint256) {
        require(_quarter >= 1 && _quarter <= 4, "Quarter must be 1 through 4");
        require(quarter[_quarter].homeDataState == DataState.Complete, "Home Score Not Set");
        require(quarter[_quarter].awayDataState == DataState.Complete, "Away Score Not Set");

        if(_quarter == 4){
            return getTile(
                quarter[5].homeScoreTotal.mod(10),
                quarter[5].awayScoreTotal.mod(10)
            );
        }
        else {
            return getTile(
                quarter[_quarter].homeScoreTotal.mod(10),
                quarter[_quarter].awayScoreTotal.mod(10)
            );
        }
        
    }

    function setBaseURI(string memory _URI) public override(SquaresNFT) onlyOwner {
        super.setBaseURI(_URI);
    }

    function startClaim() public override(SquaresNFT) onlyOwner {
        super.startClaim();
    }

    function withdrawBalance() public onlyOwner {
        require(quarterPrizeClaimed[1],"Quarter 1  prize not claimed");
        require(quarterPrizeClaimed[2],"Quarter 1  prize not claimed");
        require(quarterPrizeClaimed[3],"Quarter 1  prize not claimed");
        require(quarterPrizeClaimed[4],"Quarter 1  prize not claimed");
        require(payable(owner()).send(address(this).balance));
    }

    // To be used in the event of an emergency. Should there be a contract failure, having this
    // function in place will allow winners to be paid manually. 
    // If this function is called, expect a post mortem from: MorrisMustang.eth, howieDoin.eth

    function emergencyRug() public onlyOwner {
        require(payable(owner()).send(address(this).balance));
    }

}
// File: Tag.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.10;

//                      ---------------[ ]---------------
//                      -------[ ]-------------[ ]-------
//                      ---------------------------------
//                      ----[ ]--------[ ]--------[ ]----
//                      ---------------------------------
//                      -------[ ]-------------[ ]-------
//                      ---------------[ ]---------------


// File: SquaresNFT.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.11;

import "@openzeppelin/contracts/token/ERC721/ERC721.sol";
import "@openzeppelin/contracts/token/ERC721/extensions/ERC721Enumerable.sol";
import "@openzeppelin/contracts/utils/math/SafeMath.sol";
import "@openzeppelin/contracts/utils/Counters.sol";
import "@openzeppelin/contracts/utils/Address.sol";

enum ClaimState {
        Off,
        Active,
        SoldOut
    }

contract SquaresNFT is ERC721, ERC721Enumerable  {

    using SafeMath for uint256;
    using Address for address;
    using Counters for Counters.Counter;

    uint256 public constant MAX_TILE_NUMBER = 100;
    Counters.Counter private tileCounter; 

    ClaimState public claimState;
    string public baseURI;

    mapping(uint256 => bool) public tilePurchased;
    mapping(address => bool) public addressHasPurchased;

    constructor() ERC721("SQUARES", "SQUARES") {
        claimState = ClaimState.Off;
    }

    function mint(uint256 _tile) external payable {
        require(claimState == ClaimState.Active, "Sale not active");
        require(_tile <= MAX_TILE_NUMBER, "Tile number must be below 100");
        require(_tile > 0,"Tile 0 is not valid");
        require(!tilePurchased[_tile], "Tile already purchased");
        require(!addressHasPurchased[msg.sender], "Caller has already purchased a tile");
        require(!msg.sender.isContract(),"Caller cannot be a smart contract");

        _safeMint(msg.sender, _tile);
        tileCounter.increment();
        addressHasPurchased[msg.sender] = true;
        tilePurchased[_tile] = true;

        if(tileCounter.current()==100){
            stopClaim();
        }
        
    }

    function startClaim() public virtual{
        require(claimState == ClaimState.Off, "Sale already started and/or completed");
        claimState = ClaimState.Active;
    }
    
    function stopClaim() private {
        claimState = ClaimState.SoldOut;
    }

    function setBaseURI(string memory _URI) public virtual {
        baseURI = _URI;
    }

    function _baseURI() internal view override(ERC721) returns (string memory) {
        return baseURI;
    }

    // Read only, not to be used in smart contract calls
    function getTileOwners(uint256 _lower, uint256 _upper) public view returns (address[] memory) {
        require(_upper < 101, "Upper cannot exceed 100");
        require(_lower > 0, "Lower must be greater than zero");
        require(_upper > _lower, "Upper must be larger than lower");
        address[] memory tileOwners = new address[](100);
        for(uint256 i = _lower; i <= _upper; i++ ){
            if(tilePurchased[i]){
                tileOwners[i-1] = ownerOf(i);
            }
            else{
                tileOwners[i-1] = address(0);
            }
        }
        return tileOwners;

    }

    function _beforeTokenTransfer(address from, address to, uint256 tokenId)
        internal
        override(ERC721, ERC721Enumerable)
    {
        super._beforeTokenTransfer(from, to, tokenId);
    }

    function supportsInterface(bytes4 interfaceId)
        public
        view
        override(ERC721, ERC721Enumerable)
        returns (bool)
    {
        return super.supportsInterface(interfaceId);
    }
}
// File: RandomGameBoard.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.11;

import "@openzeppelin/contracts/utils/math/SafeMath.sol";
import "@chainlink/contracts/src/v0.8/VRFConsumerBase.sol";

enum GameState {
    PreReveal,
    GettingVRF,
    ReceivedVRF,
    Set,
    Complete
}

contract RandomGameBoard is VRFConsumerBase {

    using SafeMath for uint256;

    GameState public gameState;

    uint256[] internal homeTeam = new uint256[](10);
    uint256[] internal awayTeam = new uint256[](10);
    mapping(uint256 => uint256) public homeTeamMap;
    mapping(uint256 => uint256) public awayTeamMap;
    bool public teamAssignment;
    uint256[] public possibleScores = [0,1,2,3,4,5,6,7,8,9];

    uint256[] public homeTeamRandomness;
    uint256[] public awayTeamRandomness;
    uint256 public teamAssignmentRandomness;

    bytes32 internal keyHash;
    uint256 internal VRFfee;
    bytes32 internal VRFRequestId;

    constructor()
    VRFConsumerBase(
        0xf0d54349aDdcf704F77AE15b96510dEA15cb7952, // VRF Coordinator
        0x514910771AF9Ca656af840dff83E8264EcF986CA  // LINK Token
    ) 
    {
        gameState = GameState.PreReveal;

        keyHash = 0xAA77729D3466CA35AE8D28B3BBAC7CC36A5031EFDC430821C02BC31A238AF445;
        VRFfee = 2 ether;

        homeTeamRandomness = new uint256[](9);
        awayTeamRandomness = new uint256[](9);
    }

    function getGameBoardRandomness() public virtual returns (bytes32) {
        require(LINK.balanceOf(address(this)) >= VRFfee, "Not enough LINK - fill contract with faucet");
        return requestRandomness(keyHash, VRFfee);
    }

    /**
     * Callback function used by VRF Coordinator
     */
    function fulfillRandomness(bytes32 requestId, uint256 randomness) internal override {
        require(gameState == GameState.PreReveal,"Game must be in initial state");
        gameState = GameState.GettingVRF;
        assignRandomness(randomness);
    }

    function assignRandomness(uint256 _randomness) internal {
        require(gameState == GameState.GettingVRF,"Game must be in initial state");
        gameState = GameState.ReceivedVRF;

        uint256 nextRandomNumber = uint256(keccak256(abi.encode(_randomness)));

        for(uint256 i=0; i < 9; i++){
            nextRandomNumber = uint256(keccak256(abi.encode(nextRandomNumber)));
            homeTeamRandomness[i] = nextRandomNumber;
            
        }

        for(uint256 i=0; i < 9; i++){
            nextRandomNumber = uint256(keccak256(abi.encode(nextRandomNumber)));
            awayTeamRandomness[i] = nextRandomNumber;
        }

        nextRandomNumber = uint256(keccak256(abi.encode(nextRandomNumber)));
        teamAssignmentRandomness = nextRandomNumber;

    }

    function assignGameBoard() public virtual {
        require(gameState == GameState.ReceivedVRF, "Game in wrong state");
        gameState = GameState.Set;
        
        uint256[] memory digits = possibleScores;
        uint256 randomNumberInRange = 0;

        for(uint256 i = 0; i < 9; i++){
            randomNumberInRange = getRandomNumberInRange(homeTeamRandomness[i],0+i,9);
            digits = swapArrayElement(digits,i,randomNumberInRange);
            homeTeamMap[digits[i]] = i;
        }
        homeTeam = digits;

        digits = possibleScores;

        for(uint256 i = 0; i < 9; i++){
            randomNumberInRange = getRandomNumberInRange(awayTeamRandomness[i],0+i,9);
            digits = swapArrayElement(digits,i,randomNumberInRange);
            awayTeamMap[digits[i]] = i;
        }
        awayTeam = digits;

        randomNumberInRange = getRandomNumberInRange(teamAssignmentRandomness, 0, 1);
        
        if(randomNumberInRange == 0){
            teamAssignment = false;
        }
        else{
            teamAssignment = true;
        }

    }

    function swapArrayElement(uint256[] memory initialArray, uint256 firstElement, uint256 secondElement) public pure returns (uint256[] memory){
        uint256 temp = initialArray[firstElement];
        initialArray[firstElement] = initialArray[secondElement];
        initialArray[secondElement] = temp;
        return initialArray;
    }

    function getRandomNumberInRange(uint256 randomness, uint256 lowerBound, uint256 upperBound) public pure returns (uint256){
        return randomness.mod(upperBound.sub(lowerBound).add(1)).add(lowerBound);
    }

    function getHomeTeamArray() public view returns (uint256[] memory){
        uint256[] memory homeTeamArray = new uint256[](10);
        for(uint256 i = 0; i < 10; i++){
            homeTeamArray[i] = homeTeam[i];
        }
        return homeTeamArray;
    }

    function getAwayTeamArray() public view returns (uint256[] memory){
        uint256[] memory awayTeamArray = new uint256[](10);
        for(uint256 i = 0; i < 10; i++){
            awayTeamArray[i] = awayTeam[i];
        }
        return awayTeamArray;
    }
    

}
// File: SportsDataAPIConsumer.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.11;

import "@chainlink/contracts/src/v0.8/ChainlinkClient.sol";
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";

enum DataState {
    Waiting,
    Getting,
    SetRaw,
    Complete
}

struct Quarter {
    uint256 homeScoreQuarter;
    uint256 awayScoreQuarter;
    uint256 homeScoreTotal;
    uint256 awayScoreTotal;
    DataState homeDataState;
    DataState awayDataState;
    string homePath;
    string awayPath;
}

contract SportsDataAPIConsumer is ChainlinkClient  {

    using Chainlink for Chainlink.Request;

    struct JobSpec {
        uint256 quarter;
        // 1 - home, 2 - away
        uint256 team;
    }

    mapping(uint256 => Quarter) public quarter;
    mapping(bytes32 => JobSpec) public jobSpecs;

    bytes32 private jobId;
    uint256 public dataFee;
    DataState public gameScoreDataState;

    event ScoresReceived(uint256 _quarter, uint256 _team, uint256 _score);

    /**
     * Network: Mainnet
     * Oracle: 0x0aefab6f66d0278B99B6eCbFa8a03f9828cD90b0 (Atlas Chainlink Node) 
     * Job ID: 47a7f197fec844fc8c1fe259441bd3dc
     * Fee: 2 LINK
     */
    constructor(address _oracleAddress){
        setPublicChainlinkToken();
        setChainlinkOracle(_oracleAddress);
        // Mainnet
        jobId = "47a7f197fec844fc8c1fe259441bd3dc";

        dataFee = 2 ether;  

        gameScoreDataState = DataState.Waiting;

        quarter[1].homePath = "0,HomeScoreQuarter1";
        quarter[1].awayPath = "0,AwayScoreQuarter1";
        quarter[2].homePath = "0,HomeScoreQuarter2";
        quarter[2].awayPath = "0,AwayScoreQuarter2";
        quarter[3].homePath = "0,HomeScoreQuarter3";
        quarter[3].awayPath = "0,AwayScoreQuarter3";
        quarter[4].homePath = "0,HomeScoreQuarter4";
        quarter[4].awayPath = "0,AwayScoreQuarter4";
        quarter[5].homePath = "0,HomeScoreOvertime";
        quarter[5].awayPath = "0,AwayScoreOvertime";

    }

    function getGameScores() public virtual {
        for(uint256 i = 1; i <= 5; i++){
            requestQuarterScoreData(i);
        }
    }

    function requestQuarterScoreData(uint256 _quarter) internal {
        require(_quarter > 0, "Quarter must be greater than 0");
        require(_quarter <= 5, "Quarter must be less than or equal to 5, includes overtime");
        require(quarter[_quarter].homeDataState == DataState.Waiting, "Quarter score lookup already initiated");
        require(quarter[_quarter].awayDataState == DataState.Waiting, "Quarter score lookup already initiated");
        jobSpecs[requestScoreData(quarter[_quarter].homePath)] = JobSpec({quarter: _quarter, team: 1});
        jobSpecs[requestScoreData(quarter[_quarter].awayPath)] = JobSpec({quarter: _quarter, team: 2});

        quarter[_quarter].homeDataState = DataState.Getting;
        quarter[_quarter].awayDataState = DataState.Getting;
    }

    function requestScoreData(string memory _dataPath) private returns (bytes32 requestId) 
    {
        require(IERC20(chainlinkTokenAddress()).balanceOf(address(this)) >= dataFee, "Not enough LINK - fill contract with faucet");
        Chainlink.Request memory request = buildChainlinkRequest(jobId, address(this), this.fulfill.selector);
    
        request.add("path", _dataPath);
        
        return sendChainlinkRequest(request, dataFee);
    }
    
    /**
     * Receive the response in the form of uint256
     */ 
    function fulfill(bytes32 _requestId, uint256 _score) public recordChainlinkFulfillment(_requestId)
    {
        // home team score
        if(jobSpecs[_requestId].team==1){
            quarter[jobSpecs[_requestId].quarter].homeScoreQuarter = _score;
            quarter[jobSpecs[_requestId].quarter].homeDataState = DataState.SetRaw;
            emit ScoresReceived(jobSpecs[_requestId].quarter, 1, _score);
        }
        else if (jobSpecs[_requestId].team==2){
            quarter[jobSpecs[_requestId].quarter].awayScoreQuarter = _score;
            quarter[jobSpecs[_requestId].quarter].awayDataState = DataState.SetRaw;
            emit ScoresReceived(jobSpecs[_requestId].quarter, 2, _score);
        }

        if(allQuartersScoresReturned()){
            sumQuarterScores();
            gameScoreDataState = DataState.Complete;
        }
        
    }

    function sumQuarterScores() private {

        quarter[1].homeScoreTotal = quarter[1].homeScoreQuarter;
        quarter[1].homeDataState = DataState.Complete;
        quarter[1].awayScoreTotal = quarter[1].awayScoreQuarter;
        quarter[1].awayDataState = DataState.Complete;

        for(uint256 i = 2; i <= 5; i++ ){
            quarter[i].homeScoreTotal = quarter[i].homeScoreQuarter + quarter[i-1].homeScoreTotal;
            quarter[i].homeDataState = DataState.Complete;
            quarter[i].awayScoreTotal = quarter[i].awayScoreQuarter + quarter[i-1].awayScoreTotal;
            quarter[i].awayDataState = DataState.Complete;
        }

    }

    function allQuartersScoresReturned() private view returns (bool){
        for(uint256 i = 1; i <= 5; i++){
            if (
                quarter[i].homeDataState != DataState.SetRaw ||
                quarter[i].awayDataState != DataState.SetRaw 
            )
            {
                return false;
            }
            
        }
        return true;
    }

}
// File: AdAuction.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.11;

import "@openzeppelin/contracts/utils/Counters.sol";
import "@openzeppelin/contracts/utils/structs/EnumerableSet.sol";

contract AdAuction {

    using Counters for Counters.Counter;
    using EnumerableSet for EnumerableSet.AddressSet;

    bool public adSaleActive;

    string public diamondSponsorAd;
    address public diamondSponsor;
    uint256 public lastAmountPaid;
    uint256 public diamondSponsorshipBlockNumber;
    uint256 public minimumAirtimeInBlocks;
    Counters.Counter private diamondSponsorshipCounter;

    EnumerableSet.AddressSet private platinumSponsors;
    uint256 public platinumSponsorshipRate;

    EnumerableSet.AddressSet private goldSponsors;
    uint256 public goldSponsorshipRate;

    EnumerableSet.AddressSet private silverSponsors;
    uint256 public silverSponsorshipRate;

    event DiamondSponsorReplaced(address _address, uint256 _amount);
    event PlatinumSponsorAdded(address _address);
    event GoldSponsorAdded(address _address);
    event SilverSponsorAdded(address _address);

    constructor(string memory _initialDiamondSponsorAd, address _initialDiamondSponsor){
        diamondSponsorAd = _initialDiamondSponsorAd;
        diamondSponsor = _initialDiamondSponsor;
        lastAmountPaid = 0;
        minimumAirtimeInBlocks = 20;

        platinumSponsorshipRate = 0.25 ether;
        goldSponsorshipRate = 0.1 ether;
        silverSponsorshipRate = 0.05 ether;
    }

    function diamondSponsorship(string calldata _ad) public payable {
        require(bytes(_ad).length<=32,"Ad cannot be greater than 32 characters");
        require(msg.value > lastAmountPaid, "Caller must pay more than previous Advertiser");
        require(block.timestamp >= diamondSponsorshipBlockNumber + minimumAirtimeInBlocks,"Must wait at leaast 10 blocks between ads");
        require(adSaleActive,"Ad sale not active");
        diamondSponsorAd = _ad;
        diamondSponsor = msg.sender;
        diamondSponsorshipBlockNumber = block.timestamp;
        lastAmountPaid = msg.value;
        diamondSponsorshipCounter.increment();

        emit DiamondSponsorReplaced(msg.sender, msg.value);
    }

    function platinumSponsorship() public payable {
        require(msg.value >= platinumSponsorshipRate, "Caller must send correct amount");
        require(platinumSponsors.add(msg.sender),"Caller already a Platinum Sponsor");
        require(adSaleActive,"Ad sale not active");

        emit PlatinumSponsorAdded(msg.sender);
    }

    function goldSponsorship() public payable {
        require(msg.value >= goldSponsorshipRate, "Caller must send correct amount");
        require(goldSponsors.add(msg.sender),"Caller already a Gold Sponsor");
        require(adSaleActive,"Ad sale not active");

        emit GoldSponsorAdded(msg.sender);
    }

    function silverSponsorship() public payable {
        require(msg.value >= silverSponsorshipRate, "Caller must send correct amount");
        require(silverSponsors.add(msg.sender),"Caller already a Silver Sponsor");
        require(adSaleActive,"Ad sale not active");

        emit SilverSponsorAdded(msg.sender);
    }

    function startAdSale() public virtual {
        require(!adSaleActive, "Ad sale already active");
        adSaleActive = true;
    }

    function stopAdSale() public virtual {
        require(adSaleActive, "Ad sale off");
        adSaleActive = false;
    }

    function getPlatinumSponsors() public view returns (address[] memory){
        return platinumSponsors.values();
    }

    function getGoldSponsors() public view returns (address[] memory){
        return goldSponsors.values();
    }

    function getSilverSponsors() public view returns (address[] memory){
        return silverSponsors.values();
    }

}
// File: @openzeppelin/contracts/utils/math/SafeMath.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/math/SafeMath.sol)

pragma solidity ^0.8.0;

// CAUTION
// This version of SafeMath should only be used with Solidity 0.8 or later,
// because it relies on the compiler's built in overflow checks.

/**
 * @dev Wrappers over Solidity's arithmetic operations.
 *
 * NOTE: `SafeMath` is generally not needed starting with Solidity 0.8, since the compiler
 * now has built in overflow checking.
 */
library SafeMath {
    /**
     * @dev Returns the addition of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryAdd(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            uint256 c = a + b;
            if (c < a) return (false, 0);
            return (true, c);
        }
    }

    /**
     * @dev Returns the substraction of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function trySub(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            if (b > a) return (false, 0);
            return (true, a - b);
        }
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryMul(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            // 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-contracts/pull/522
            if (a == 0) return (true, 0);
            uint256 c = a * b;
            if (c / a != b) return (false, 0);
            return (true, c);
        }
    }

    /**
     * @dev Returns the division of two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryDiv(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            if (b == 0) return (false, 0);
            return (true, a / b);
        }
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryMod(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            if (b == 0) return (false, 0);
            return (true, a % b);
        }
    }

    /**
     * @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) {
        return a + b;
    }

    /**
     * @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) {
        return a - b;
    }

    /**
     * @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) {
        return a * b;
    }

    /**
     * @dev Returns the integer division of two unsigned integers, reverting on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator.
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        return a / b;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting 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) {
        return a % b;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {trySub}.
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(
        uint256 a,
        uint256 b,
        string memory errorMessage
    ) internal pure returns (uint256) {
        unchecked {
            require(b <= a, errorMessage);
            return a - b;
        }
    }

    /**
     * @dev Returns the integer division of two unsigned integers, reverting with custom message 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,
        string memory errorMessage
    ) internal pure returns (uint256) {
        unchecked {
            require(b > 0, errorMessage);
            return a / b;
        }
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting with custom message when dividing by zero.
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {tryMod}.
     *
     * 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,
        string memory errorMessage
    ) internal pure returns (uint256) {
        unchecked {
            require(b > 0, errorMessage);
            return a % b;
        }
    }
}

// File: @openzeppelin/contracts/access/Ownable.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (access/Ownable.sol)

pragma solidity ^0.8.0;

import "../utils/Context.sol";

/**
 * @dev Contract module which provides a basic access control mechanism, where
 * there is an account (an owner) that can be granted exclusive access to
 * specific functions.
 *
 * By default, the owner account will be the one that deploys the contract. This
 * can later be changed with {transferOwnership}.
 *
 * This module is used through inheritance. It will make available the modifier
 * `onlyOwner`, which can be applied to your functions to restrict their use to
 * the owner.
 */
abstract contract Ownable is Context {
    address private _owner;

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    constructor() {
        _transferOwnership(_msgSender());
    }

    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view virtual returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        require(owner() == _msgSender(), "Ownable: caller is not the owner");
        _;
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions anymore. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby removing any functionality that is only available to the owner.
     */
    function renounceOwnership() public virtual onlyOwner {
        _transferOwnership(address(0));
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public virtual onlyOwner {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        _transferOwnership(newOwner);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Internal function without access restriction.
     */
    function _transferOwnership(address newOwner) internal virtual {
        address oldOwner = _owner;
        _owner = newOwner;
        emit OwnershipTransferred(oldOwner, newOwner);
    }
}

// File: @openzeppelin/contracts/token/ERC721/IERC721.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC721/IERC721.sol)

pragma solidity ^0.8.0;

import "../../utils/introspection/IERC165.sol";

/**
 * @dev Required interface of an ERC721 compliant contract.
 */
interface IERC721 is IERC165 {
    /**
     * @dev Emitted when `tokenId` token is transferred from `from` to `to`.
     */
    event Transfer(address indexed from, address indexed to, uint256 indexed tokenId);

    /**
     * @dev Emitted when `owner` enables `approved` to manage the `tokenId` token.
     */
    event Approval(address indexed owner, address indexed approved, uint256 indexed tokenId);

    /**
     * @dev Emitted when `owner` enables or disables (`approved`) `operator` to manage all of its assets.
     */
    event ApprovalForAll(address indexed owner, address indexed operator, bool approved);

    /**
     * @dev Returns the number of tokens in ``owner``'s account.
     */
    function balanceOf(address owner) external view returns (uint256 balance);

    /**
     * @dev Returns the owner of the `tokenId` token.
     *
     * Requirements:
     *
     * - `tokenId` must exist.
     */
    function ownerOf(uint256 tokenId) external view returns (address owner);

    /**
     * @dev Safely transfers `tokenId` token from `from` to `to`, checking first that contract recipients
     * are aware of the ERC721 protocol to prevent tokens from being forever locked.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `tokenId` token must exist and be owned by `from`.
     * - If the caller is not `from`, it must be have been allowed to move this token by either {approve} or {setApprovalForAll}.
     * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
     *
     * Emits a {Transfer} event.
     */
    function safeTransferFrom(
        address from,
        address to,
        uint256 tokenId
    ) external;

    /**
     * @dev Transfers `tokenId` token from `from` to `to`.
     *
     * WARNING: Usage of this method is discouraged, use {safeTransferFrom} whenever possible.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `tokenId` token must be owned by `from`.
     * - If the caller is not `from`, it must be approved to move this token by either {approve} or {setApprovalForAll}.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(
        address from,
        address to,
        uint256 tokenId
    ) external;

    /**
     * @dev Gives permission to `to` to transfer `tokenId` token to another account.
     * The approval is cleared when the token is transferred.
     *
     * Only a single account can be approved at a time, so approving the zero address clears previous approvals.
     *
     * Requirements:
     *
     * - The caller must own the token or be an approved operator.
     * - `tokenId` must exist.
     *
     * Emits an {Approval} event.
     */
    function approve(address to, uint256 tokenId) external;

    /**
     * @dev Returns the account approved for `tokenId` token.
     *
     * Requirements:
     *
     * - `tokenId` must exist.
     */
    function getApproved(uint256 tokenId) external view returns (address operator);

    /**
     * @dev Approve or remove `operator` as an operator for the caller.
     * Operators can call {transferFrom} or {safeTransferFrom} for any token owned by the caller.
     *
     * Requirements:
     *
     * - The `operator` cannot be the caller.
     *
     * Emits an {ApprovalForAll} event.
     */
    function setApprovalForAll(address operator, bool _approved) external;

    /**
     * @dev Returns if the `operator` is allowed to manage all of the assets of `owner`.
     *
     * See {setApprovalForAll}
     */
    function isApprovedForAll(address owner, address operator) external view returns (bool);

    /**
     * @dev Safely transfers `tokenId` token from `from` to `to`.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `tokenId` token must exist and be owned by `from`.
     * - If the caller is not `from`, it must be approved to move this token by either {approve} or {setApprovalForAll}.
     * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
     *
     * Emits a {Transfer} event.
     */
    function safeTransferFrom(
        address from,
        address to,
        uint256 tokenId,
        bytes calldata data
    ) external;
}

// File: @openzeppelin/contracts/utils/Address.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.5.0) (utils/Address.sol)

pragma solidity ^0.8.1;

/**
 * @dev Collection of functions related to the address type
 */
library Address {
    /**
     * @dev Returns true if `account` is a contract.
     *
     * [IMPORTANT]
     * ====
     * It is unsafe to assume that an address for which this function returns
     * false is an externally-owned account (EOA) and not a contract.
     *
     * Among others, `isContract` will return false for the following
     * types of addresses:
     *
     *  - an externally-owned account
     *  - a contract in construction
     *  - an address where a contract will be created
     *  - an address where a contract lived, but was destroyed
     * ====
     *
     * [IMPORTANT]
     * ====
     * You shouldn't rely on `isContract` to protect against flash loan attacks!
     *
     * Preventing calls from contracts is highly discouraged. It breaks composability, breaks support for smart wallets
     * like Gnosis Safe, and does not provide security since it can be circumvented by calling from a contract
     * constructor.
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize/address.code.length, which returns 0
        // for contracts in construction, since the code is only stored at the end
        // of the constructor execution.

        return account.code.length > 0;
    }

    /**
     * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
     * `recipient`, forwarding all available gas and reverting on errors.
     *
     * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
     * of certain opcodes, possibly making contracts go over the 2300 gas limit
     * imposed by `transfer`, making them unable to receive funds via
     * `transfer`. {sendValue} removes this limitation.
     *
     * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
     *
     * IMPORTANT: because control is transferred to `recipient`, care must be
     * taken to not create reentrancy vulnerabilities. Consider using
     * {ReentrancyGuard} or the
     * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");

        (bool success, ) = recipient.call{value: amount}("");
        require(success, "Address: unable to send value, recipient may have reverted");
    }

    /**
     * @dev Performs a Solidity function call using a low level `call`. A
     * plain `call` is an unsafe replacement for a function call: use this
     * function instead.
     *
     * If `target` reverts with a revert reason, it is bubbled up by this
     * function (like regular Solidity function calls).
     *
     * Returns the raw returned data. To convert to the expected return value,
     * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
     *
     * Requirements:
     *
     * - `target` must be a contract.
     * - calling `target` with `data` must not revert.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionCall(target, data, "Address: low-level call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
     * `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but also transferring `value` wei to `target`.
     *
     * Requirements:
     *
     * - the calling contract must have an ETH balance of at least `value`.
     * - the called Solidity function must be `payable`.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(
        address target,
        bytes memory data,
        uint256 value
    ) internal returns (bytes memory) {
        return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
    }

    /**
     * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
     * with `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(
        address target,
        bytes memory data,
        uint256 value,
        string memory errorMessage
    ) internal returns (bytes memory) {
        require(address(this).balance >= value, "Address: insufficient balance for call");
        require(isContract(target), "Address: call to non-contract");

        (bool success, bytes memory returndata) = target.call{value: value}(data);
        return verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
        return functionStaticCall(target, data, "Address: low-level static call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal view returns (bytes memory) {
        require(isContract(target), "Address: static call to non-contract");

        (bool success, bytes memory returndata) = target.staticcall(data);
        return verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionDelegateCall(target, data, "Address: low-level delegate call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        require(isContract(target), "Address: delegate call to non-contract");

        (bool success, bytes memory returndata) = target.delegatecall(data);
        return verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Tool to verifies that a low level call was successful, and revert if it wasn't, either by bubbling the
     * revert reason using the provided one.
     *
     * _Available since v4.3._
     */
    function verifyCallResult(
        bool success,
        bytes memory returndata,
        string memory errorMessage
    ) internal pure returns (bytes memory) {
        if (success) {
            return returndata;
        } else {
            // Look for revert reason and bubble it up if present
            if (returndata.length > 0) {
                // The easiest way to bubble the revert reason is using memory via assembly

                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}

// File: @openzeppelin/contracts/utils/Counters.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/Counters.sol)

pragma solidity ^0.8.0;

/**
 * @title Counters
 * @author Matt Condon (@shrugs)
 * @dev Provides counters that can only be incremented, decremented or reset. This can be used e.g. to track the number
 * of elements in a mapping, issuing ERC721 ids, or counting request ids.
 *
 * Include with `using Counters for Counters.Counter;`
 */
library Counters {
    struct Counter {
        // This variable should never be directly accessed by users of the library: interactions must be restricted to
        // the library's function. As of Solidity v0.5.2, this cannot be enforced, though there is a proposal to add
        // this feature: see https://github.com/ethereum/solidity/issues/4637
        uint256 _value; // default: 0
    }

    function current(Counter storage counter) internal view returns (uint256) {
        return counter._value;
    }

    function increment(Counter storage counter) internal {
        unchecked {
            counter._value += 1;
        }
    }

    function decrement(Counter storage counter) internal {
        uint256 value = counter._value;
        require(value > 0, "Counter: decrement overflow");
        unchecked {
            counter._value = value - 1;
        }
    }

    function reset(Counter storage counter) internal {
        counter._value = 0;
    }
}

// File: @openzeppelin/contracts/token/ERC721/extensions/ERC721Enumerable.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC721/extensions/ERC721Enumerable.sol)

pragma solidity ^0.8.0;

import "../ERC721.sol";
import "./IERC721Enumerable.sol";

/**
 * @dev This implements an optional extension of {ERC721} defined in the EIP that adds
 * enumerability of all the token ids in the contract as well as all token ids owned by each
 * account.
 */
abstract contract ERC721Enumerable is ERC721, IERC721Enumerable {
    // Mapping from owner to list of owned token IDs
    mapping(address => mapping(uint256 => uint256)) private _ownedTokens;

    // Mapping from token ID to index of the owner tokens list
    mapping(uint256 => uint256) private _ownedTokensIndex;

    // Array with all token ids, used for enumeration
    uint256[] private _allTokens;

    // Mapping from token id to position in the allTokens array
    mapping(uint256 => uint256) private _allTokensIndex;

    /**
     * @dev See {IERC165-supportsInterface}.
     */
    function supportsInterface(bytes4 interfaceId) public view virtual override(IERC165, ERC721) returns (bool) {
        return interfaceId == type(IERC721Enumerable).interfaceId || super.supportsInterface(interfaceId);
    }

    /**
     * @dev See {IERC721Enumerable-tokenOfOwnerByIndex}.
     */
    function tokenOfOwnerByIndex(address owner, uint256 index) public view virtual override returns (uint256) {
        require(index < ERC721.balanceOf(owner), "ERC721Enumerable: owner index out of bounds");
        return _ownedTokens[owner][index];
    }

    /**
     * @dev See {IERC721Enumerable-totalSupply}.
     */
    function totalSupply() public view virtual override returns (uint256) {
        return _allTokens.length;
    }

    /**
     * @dev See {IERC721Enumerable-tokenByIndex}.
     */
    function tokenByIndex(uint256 index) public view virtual override returns (uint256) {
        require(index < ERC721Enumerable.totalSupply(), "ERC721Enumerable: global index out of bounds");
        return _allTokens[index];
    }

    /**
     * @dev Hook that is called before any token transfer. This includes minting
     * and burning.
     *
     * Calling conditions:
     *
     * - When `from` and `to` are both non-zero, ``from``'s `tokenId` will be
     * transferred to `to`.
     * - When `from` is zero, `tokenId` will be minted for `to`.
     * - When `to` is zero, ``from``'s `tokenId` will be burned.
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     *
     * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
     */
    function _beforeTokenTransfer(
        address from,
        address to,
        uint256 tokenId
    ) internal virtual override {
        super._beforeTokenTransfer(from, to, tokenId);

        if (from == address(0)) {
            _addTokenToAllTokensEnumeration(tokenId);
        } else if (from != to) {
            _removeTokenFromOwnerEnumeration(from, tokenId);
        }
        if (to == address(0)) {
            _removeTokenFromAllTokensEnumeration(tokenId);
        } else if (to != from) {
            _addTokenToOwnerEnumeration(to, tokenId);
        }
    }

    /**
     * @dev Private function to add a token to this extension's ownership-tracking data structures.
     * @param to address representing the new owner of the given token ID
     * @param tokenId uint256 ID of the token to be added to the tokens list of the given address
     */
    function _addTokenToOwnerEnumeration(address to, uint256 tokenId) private {
        uint256 length = ERC721.balanceOf(to);
        _ownedTokens[to][length] = tokenId;
        _ownedTokensIndex[tokenId] = length;
    }

    /**
     * @dev Private function to add a token to this extension's token tracking data structures.
     * @param tokenId uint256 ID of the token to be added to the tokens list
     */
    function _addTokenToAllTokensEnumeration(uint256 tokenId) private {
        _allTokensIndex[tokenId] = _allTokens.length;
        _allTokens.push(tokenId);
    }

    /**
     * @dev Private function to remove a token from this extension's ownership-tracking data structures. Note that
     * while the token is not assigned a new owner, the `_ownedTokensIndex` mapping is _not_ updated: this allows for
     * gas optimizations e.g. when performing a transfer operation (avoiding double writes).
     * This has O(1) time complexity, but alters the order of the _ownedTokens array.
     * @param from address representing the previous owner of the given token ID
     * @param tokenId uint256 ID of the token to be removed from the tokens list of the given address
     */
    function _removeTokenFromOwnerEnumeration(address from, uint256 tokenId) private {
        // To prevent a gap in from's tokens array, we store the last token in the index of the token to delete, and
        // then delete the last slot (swap and pop).

        uint256 lastTokenIndex = ERC721.balanceOf(from) - 1;
        uint256 tokenIndex = _ownedTokensIndex[tokenId];

        // When the token to delete is the last token, the swap operation is unnecessary
        if (tokenIndex != lastTokenIndex) {
            uint256 lastTokenId = _ownedTokens[from][lastTokenIndex];

            _ownedTokens[from][tokenIndex] = lastTokenId; // Move the last token to the slot of the to-delete token
            _ownedTokensIndex[lastTokenId] = tokenIndex; // Update the moved token's index
        }

        // This also deletes the contents at the last position of the array
        delete _ownedTokensIndex[tokenId];
        delete _ownedTokens[from][lastTokenIndex];
    }

    /**
     * @dev Private function to remove a token from this extension's token tracking data structures.
     * This has O(1) time complexity, but alters the order of the _allTokens array.
     * @param tokenId uint256 ID of the token to be removed from the tokens list
     */
    function _removeTokenFromAllTokensEnumeration(uint256 tokenId) private {
        // To prevent a gap in the tokens array, we store the last token in the index of the token to delete, and
        // then delete the last slot (swap and pop).

        uint256 lastTokenIndex = _allTokens.length - 1;
        uint256 tokenIndex = _allTokensIndex[tokenId];

        // When the token to delete is the last token, the swap operation is unnecessary. However, since this occurs so
        // rarely (when the last minted token is burnt) that we still do the swap here to avoid the gas cost of adding
        // an 'if' statement (like in _removeTokenFromOwnerEnumeration)
        uint256 lastTokenId = _allTokens[lastTokenIndex];

        _allTokens[tokenIndex] = lastTokenId; // Move the last token to the slot of the to-delete token
        _allTokensIndex[lastTokenId] = tokenIndex; // Update the moved token's index

        // This also deletes the contents at the last position of the array
        delete _allTokensIndex[tokenId];
        _allTokens.pop();
    }
}

// File: @openzeppelin/contracts/token/ERC721/ERC721.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.5.0) (token/ERC721/ERC721.sol)

pragma solidity ^0.8.0;

import "./IERC721.sol";
import "./IERC721Receiver.sol";
import "./extensions/IERC721Metadata.sol";
import "../../utils/Address.sol";
import "../../utils/Context.sol";
import "../../utils/Strings.sol";
import "../../utils/introspection/ERC165.sol";

/**
 * @dev Implementation of https://eips.ethereum.org/EIPS/eip-721[ERC721] Non-Fungible Token Standard, including
 * the Metadata extension, but not including the Enumerable extension, which is available separately as
 * {ERC721Enumerable}.
 */
contract ERC721 is Context, ERC165, IERC721, IERC721Metadata {
    using Address for address;
    using Strings for uint256;

    // Token name
    string private _name;

    // Token symbol
    string private _symbol;

    // Mapping from token ID to owner address
    mapping(uint256 => address) private _owners;

    // Mapping owner address to token count
    mapping(address => uint256) private _balances;

    // Mapping from token ID to approved address
    mapping(uint256 => address) private _tokenApprovals;

    // Mapping from owner to operator approvals
    mapping(address => mapping(address => bool)) private _operatorApprovals;

    /**
     * @dev Initializes the contract by setting a `name` and a `symbol` to the token collection.
     */
    constructor(string memory name_, string memory symbol_) {
        _name = name_;
        _symbol = symbol_;
    }

    /**
     * @dev See {IERC165-supportsInterface}.
     */
    function supportsInterface(bytes4 interfaceId) public view virtual override(ERC165, IERC165) returns (bool) {
        return
            interfaceId == type(IERC721).interfaceId ||
            interfaceId == type(IERC721Metadata).interfaceId ||
            super.supportsInterface(interfaceId);
    }

    /**
     * @dev See {IERC721-balanceOf}.
     */
    function balanceOf(address owner) public view virtual override returns (uint256) {
        require(owner != address(0), "ERC721: balance query for the zero address");
        return _balances[owner];
    }

    /**
     * @dev See {IERC721-ownerOf}.
     */
    function ownerOf(uint256 tokenId) public view virtual override returns (address) {
        address owner = _owners[tokenId];
        require(owner != address(0), "ERC721: owner query for nonexistent token");
        return owner;
    }

    /**
     * @dev See {IERC721Metadata-name}.
     */
    function name() public view virtual override returns (string memory) {
        return _name;
    }

    /**
     * @dev See {IERC721Metadata-symbol}.
     */
    function symbol() public view virtual override returns (string memory) {
        return _symbol;
    }

    /**
     * @dev See {IERC721Metadata-tokenURI}.
     */
    function tokenURI(uint256 tokenId) public view virtual override returns (string memory) {
        require(_exists(tokenId), "ERC721Metadata: URI query for nonexistent token");

        string memory baseURI = _baseURI();
        return bytes(baseURI).length > 0 ? string(abi.encodePacked(baseURI, tokenId.toString())) : "";
    }

    /**
     * @dev Base URI for computing {tokenURI}. If set, the resulting URI for each
     * token will be the concatenation of the `baseURI` and the `tokenId`. Empty
     * by default, can be overriden in child contracts.
     */
    function _baseURI() internal view virtual returns (string memory) {
        return "";
    }

    /**
     * @dev See {IERC721-approve}.
     */
    function approve(address to, uint256 tokenId) public virtual override {
        address owner = ERC721.ownerOf(tokenId);
        require(to != owner, "ERC721: approval to current owner");

        require(
            _msgSender() == owner || isApprovedForAll(owner, _msgSender()),
            "ERC721: approve caller is not owner nor approved for all"
        );

        _approve(to, tokenId);
    }

    /**
     * @dev See {IERC721-getApproved}.
     */
    function getApproved(uint256 tokenId) public view virtual override returns (address) {
        require(_exists(tokenId), "ERC721: approved query for nonexistent token");

        return _tokenApprovals[tokenId];
    }

    /**
     * @dev See {IERC721-setApprovalForAll}.
     */
    function setApprovalForAll(address operator, bool approved) public virtual override {
        _setApprovalForAll(_msgSender(), operator, approved);
    }

    /**
     * @dev See {IERC721-isApprovedForAll}.
     */
    function isApprovedForAll(address owner, address operator) public view virtual override returns (bool) {
        return _operatorApprovals[owner][operator];
    }

    /**
     * @dev See {IERC721-transferFrom}.
     */
    function transferFrom(
        address from,
        address to,
        uint256 tokenId
    ) public virtual override {
        //solhint-disable-next-line max-line-length
        require(_isApprovedOrOwner(_msgSender(), tokenId), "ERC721: transfer caller is not owner nor approved");

        _transfer(from, to, tokenId);
    }

    /**
     * @dev See {IERC721-safeTransferFrom}.
     */
    function safeTransferFrom(
        address from,
        address to,
        uint256 tokenId
    ) public virtual override {
        safeTransferFrom(from, to, tokenId, "");
    }

    /**
     * @dev See {IERC721-safeTransferFrom}.
     */
    function safeTransferFrom(
        address from,
        address to,
        uint256 tokenId,
        bytes memory _data
    ) public virtual override {
        require(_isApprovedOrOwner(_msgSender(), tokenId), "ERC721: transfer caller is not owner nor approved");
        _safeTransfer(from, to, tokenId, _data);
    }

    /**
     * @dev Safely transfers `tokenId` token from `from` to `to`, checking first that contract recipients
     * are aware of the ERC721 protocol to prevent tokens from being forever locked.
     *
     * `_data` is additional data, it has no specified format and it is sent in call to `to`.
     *
     * This internal function is equivalent to {safeTransferFrom}, and can be used to e.g.
     * implement alternative mechanisms to perform token transfer, such as signature-based.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `tokenId` token must exist and be owned by `from`.
     * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
     *
     * Emits a {Transfer} event.
     */
    function _safeTransfer(
        address from,
        address to,
        uint256 tokenId,
        bytes memory _data
    ) internal virtual {
        _transfer(from, to, tokenId);
        require(_checkOnERC721Received(from, to, tokenId, _data), "ERC721: transfer to non ERC721Receiver implementer");
    }

    /**
     * @dev Returns whether `tokenId` exists.
     *
     * Tokens can be managed by their owner or approved accounts via {approve} or {setApprovalForAll}.
     *
     * Tokens start existing when they are minted (`_mint`),
     * and stop existing when they are burned (`_burn`).
     */
    function _exists(uint256 tokenId) internal view virtual returns (bool) {
        return _owners[tokenId] != address(0);
    }

    /**
     * @dev Returns whether `spender` is allowed to manage `tokenId`.
     *
     * Requirements:
     *
     * - `tokenId` must exist.
     */
    function _isApprovedOrOwner(address spender, uint256 tokenId) internal view virtual returns (bool) {
        require(_exists(tokenId), "ERC721: operator query for nonexistent token");
        address owner = ERC721.ownerOf(tokenId);
        return (spender == owner || getApproved(tokenId) == spender || isApprovedForAll(owner, spender));
    }

    /**
     * @dev Safely mints `tokenId` and transfers it to `to`.
     *
     * Requirements:
     *
     * - `tokenId` must not exist.
     * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
     *
     * Emits a {Transfer} event.
     */
    function _safeMint(address to, uint256 tokenId) internal virtual {
        _safeMint(to, tokenId, "");
    }

    /**
     * @dev Same as {xref-ERC721-_safeMint-address-uint256-}[`_safeMint`], with an additional `data` parameter which is
     * forwarded in {IERC721Receiver-onERC721Received} to contract recipients.
     */
    function _safeMint(
        address to,
        uint256 tokenId,
        bytes memory _data
    ) internal virtual {
        _mint(to, tokenId);
        require(
            _checkOnERC721Received(address(0), to, tokenId, _data),
            "ERC721: transfer to non ERC721Receiver implementer"
        );
    }

    /**
     * @dev Mints `tokenId` and transfers it to `to`.
     *
     * WARNING: Usage of this method is discouraged, use {_safeMint} whenever possible
     *
     * Requirements:
     *
     * - `tokenId` must not exist.
     * - `to` cannot be the zero address.
     *
     * Emits a {Transfer} event.
     */
    function _mint(address to, uint256 tokenId) internal virtual {
        require(to != address(0), "ERC721: mint to the zero address");
        require(!_exists(tokenId), "ERC721: token already minted");

        _beforeTokenTransfer(address(0), to, tokenId);

        _balances[to] += 1;
        _owners[tokenId] = to;

        emit Transfer(address(0), to, tokenId);

        _afterTokenTransfer(address(0), to, tokenId);
    }

    /**
     * @dev Destroys `tokenId`.
     * The approval is cleared when the token is burned.
     *
     * Requirements:
     *
     * - `tokenId` must exist.
     *
     * Emits a {Transfer} event.
     */
    function _burn(uint256 tokenId) internal virtual {
        address owner = ERC721.ownerOf(tokenId);

        _beforeTokenTransfer(owner, address(0), tokenId);

        // Clear approvals
        _approve(address(0), tokenId);

        _balances[owner] -= 1;
        delete _owners[tokenId];

        emit Transfer(owner, address(0), tokenId);

        _afterTokenTransfer(owner, address(0), tokenId);
    }

    /**
     * @dev Transfers `tokenId` from `from` to `to`.
     *  As opposed to {transferFrom}, this imposes no restrictions on msg.sender.
     *
     * Requirements:
     *
     * - `to` cannot be the zero address.
     * - `tokenId` token must be owned by `from`.
     *
     * Emits a {Transfer} event.
     */
    function _transfer(
        address from,
        address to,
        uint256 tokenId
    ) internal virtual {
        require(ERC721.ownerOf(tokenId) == from, "ERC721: transfer from incorrect owner");
        require(to != address(0), "ERC721: transfer to the zero address");

        _beforeTokenTransfer(from, to, tokenId);

        // Clear approvals from the previous owner
        _approve(address(0), tokenId);

        _balances[from] -= 1;
        _balances[to] += 1;
        _owners[tokenId] = to;

        emit Transfer(from, to, tokenId);

        _afterTokenTransfer(from, to, tokenId);
    }

    /**
     * @dev Approve `to` to operate on `tokenId`
     *
     * Emits a {Approval} event.
     */
    function _approve(address to, uint256 tokenId) internal virtual {
        _tokenApprovals[tokenId] = to;
        emit Approval(ERC721.ownerOf(tokenId), to, tokenId);
    }

    /**
     * @dev Approve `operator` to operate on all of `owner` tokens
     *
     * Emits a {ApprovalForAll} event.
     */
    function _setApprovalForAll(
        address owner,
        address operator,
        bool approved
    ) internal virtual {
        require(owner != operator, "ERC721: approve to caller");
        _operatorApprovals[owner][operator] = approved;
        emit ApprovalForAll(owner, operator, approved);
    }

    /**
     * @dev Internal function to invoke {IERC721Receiver-onERC721Received} on a target address.
     * The call is not executed if the target address is not a contract.
     *
     * @param from address representing the previous owner of the given token ID
     * @param to target address that will receive the tokens
     * @param tokenId uint256 ID of the token to be transferred
     * @param _data bytes optional data to send along with the call
     * @return bool whether the call correctly returned the expected magic value
     */
    function _checkOnERC721Received(
        address from,
        address to,
        uint256 tokenId,
        bytes memory _data
    ) private returns (bool) {
        if (to.isContract()) {
            try IERC721Receiver(to).onERC721Received(_msgSender(), from, tokenId, _data) returns (bytes4 retval) {
                return retval == IERC721Receiver.onERC721Received.selector;
            } catch (bytes memory reason) {
                if (reason.length == 0) {
                    revert("ERC721: transfer to non ERC721Receiver implementer");
                } else {
                    assembly {
                        revert(add(32, reason), mload(reason))
                    }
                }
            }
        } else {
            return true;
        }
    }

    /**
     * @dev Hook that is called before any token transfer. This includes minting
     * and burning.
     *
     * Calling conditions:
     *
     * - When `from` and `to` are both non-zero, ``from``'s `tokenId` will be
     * transferred to `to`.
     * - When `from` is zero, `tokenId` will be minted for `to`.
     * - When `to` is zero, ``from``'s `tokenId` will be burned.
     * - `from` and `to` are never both zero.
     *
     * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
     */
    function _beforeTokenTransfer(
        address from,
        address to,
        uint256 tokenId
    ) internal virtual {}

    /**
     * @dev Hook that is called after any transfer of tokens. This includes
     * minting and burning.
     *
     * Calling conditions:
     *
     * - when `from` and `to` are both non-zero.
     * - `from` and `to` are never both zero.
     *
     * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
     */
    function _afterTokenTransfer(
        address from,
        address to,
        uint256 tokenId
    ) internal virtual {}
}

// File: @openzeppelin/contracts/token/ERC20/IERC20.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.5.0) (token/ERC20/IERC20.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns the amount of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);

    /**
     * @dev Moves `amount` tokens from the caller's account to `to`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address to, uint256 amount) external returns (bool);

    /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}. This is
     * zero by default.
     *
     * This value changes when {approve} or {transferFrom} are called.
     */
    function allowance(address owner, address spender) external view returns (uint256);

    /**
     * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * IMPORTANT: Beware that changing an allowance with this method brings the risk
     * that someone may use both the old and the new allowance by unfortunate
     * transaction ordering. One possible solution to mitigate this race
     * condition is to first reduce the spender's allowance to 0 and set the
     * desired value afterwards:
     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
     *
     * Emits an {Approval} event.
     */
    function approve(address spender, uint256 amount) external returns (bool);

    /**
     * @dev Moves `amount` tokens from `from` to `to` using the
     * allowance mechanism. `amount` is then deducted from the caller's
     * allowance.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(
        address from,
        address to,
        uint256 amount
    ) external returns (bool);

    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}. `value` is the new allowance.
     */
    event Approval(address indexed owner, address indexed spender, uint256 value);
}

// File: @chainlink/contracts/src/v0.8/ChainlinkClient.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import "./Chainlink.sol";
import "./interfaces/ENSInterface.sol";
import "./interfaces/LinkTokenInterface.sol";
import "./interfaces/ChainlinkRequestInterface.sol";
import "./interfaces/OperatorInterface.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
 */
abstract contract ChainlinkClient {
  using Chainlink for Chainlink.Request;

  uint256 internal constant LINK_DIVISIBILITY = 10**18;
  uint256 private constant AMOUNT_OVERRIDE = 0;
  address private constant SENDER_OVERRIDE = address(0);
  uint256 private constant ORACLE_ARGS_VERSION = 1;
  uint256 private constant OPERATOR_ARGS_VERSION = 2;
  bytes32 private constant ENS_TOKEN_SUBNAME = keccak256("link");
  bytes32 private constant ENS_ORACLE_SUBNAME = keccak256("oracle");
  address private constant LINK_TOKEN_POINTER = 0xC89bD4E1632D3A43CB03AAAd5262cbe4038Bc571;

  ENSInterface private s_ens;
  bytes32 private s_ensNode;
  LinkTokenInterface private s_link;
  OperatorInterface private s_oracle;
  uint256 private s_requestCount = 1;
  mapping(bytes32 => address) private s_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 callbackAddr address to operate the callback on
   * @param callbackFunctionSignature function signature to use for the callback
   * @return A Chainlink Request struct in memory
   */
  function buildChainlinkRequest(
    bytes32 specId,
    address callbackAddr,
    bytes4 callbackFunctionSignature
  ) internal pure returns (Chainlink.Request memory) {
    Chainlink.Request memory req;
    return req.initialize(specId, callbackAddr, callbackFunctionSignature);
  }

  /**
   * @notice Creates a request that can hold additional parameters
   * @param specId The Job Specification ID that the request will be created for
   * @param callbackFunctionSignature function signature to use for the callback
   * @return A Chainlink Request struct in memory
   */
  function buildOperatorRequest(bytes32 specId, bytes4 callbackFunctionSignature)
    internal
    view
    returns (Chainlink.Request memory)
  {
    Chainlink.Request memory req;
    return req.initialize(specId, address(this), 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(s_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 oracleAddress 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 oracleAddress,
    Chainlink.Request memory req,
    uint256 payment
  ) internal returns (bytes32 requestId) {
    uint256 nonce = s_requestCount;
    s_requestCount = nonce + 1;
    bytes memory encodedRequest = abi.encodeWithSelector(
      ChainlinkRequestInterface.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,
      address(this),
      req.callbackFunctionId,
      nonce,
      ORACLE_ARGS_VERSION,
      req.buf.buf
    );
    return _rawRequest(oracleAddress, nonce, payment, encodedRequest);
  }

  /**
   * @notice Creates a Chainlink request to the stored oracle address
   * @dev This function supports multi-word response
   * @dev Calls `sendOperatorRequestTo` 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 sendOperatorRequest(Chainlink.Request memory req, uint256 payment) internal returns (bytes32) {
    return sendOperatorRequestTo(address(s_oracle), req, payment);
  }

  /**
   * @notice Creates a Chainlink request to the specified oracle address
   * @dev This function supports multi-word response
   * @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 oracleAddress 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 sendOperatorRequestTo(
    address oracleAddress,
    Chainlink.Request memory req,
    uint256 payment
  ) internal returns (bytes32 requestId) {
    uint256 nonce = s_requestCount;
    s_requestCount = nonce + 1;
    bytes memory encodedRequest = abi.encodeWithSelector(
      OperatorInterface.operatorRequest.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.callbackFunctionId,
      nonce,
      OPERATOR_ARGS_VERSION,
      req.buf.buf
    );
    return _rawRequest(oracleAddress, nonce, payment, encodedRequest);
  }

  /**
   * @notice Make a request to an oracle
   * @param oracleAddress The address of the oracle for the request
   * @param nonce used to generate the request ID
   * @param payment The amount of LINK to send for the request
   * @param encodedRequest data encoded for request type specific format
   * @return requestId The request ID
   */
  function _rawRequest(
    address oracleAddress,
    uint256 nonce,
    uint256 payment,
    bytes memory encodedRequest
  ) private returns (bytes32 requestId) {
    requestId = keccak256(abi.encodePacked(this, nonce));
    s_pendingRequests[requestId] = oracleAddress;
    emit ChainlinkRequested(requestId);
    require(s_link.transferAndCall(oracleAddress, payment, encodedRequest), "unable to transferAndCall to oracle");
  }

  /**
   * @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 {
    OperatorInterface requested = OperatorInterface(s_pendingRequests[requestId]);
    delete s_pendingRequests[requestId];
    emit ChainlinkCancelled(requestId);
    requested.cancelOracleRequest(requestId, payment, callbackFunc, expiration);
  }

  /**
   * @notice the next request count to be used in generating a nonce
   * @dev starts at 1 in order to ensure consistent gas cost
   * @return returns the next request count to be used in a nonce
   */
  function getNextRequestCount() internal view returns (uint256) {
    return s_requestCount;
  }

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

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

  /**
   * @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(s_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(s_oracle);
  }

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

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

  /**
   * @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 == s_pendingRequests[requestId], "Source must be the oracle of the request");
    delete s_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(s_pendingRequests[requestId] == address(0), "Request is already pending");
    _;
  }
}

// File: @chainlink/contracts/src/v0.8/VRFConsumerBase.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

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     constructor(<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 {
  /**
   * @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 private constant 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] + 1;
    return makeRequestId(_keyHash, vRFSeed);
  }

  LinkTokenInterface internal immutable LINK;
  address private immutable vrfCoordinator;

  // Nonces for each VRF key from which randomness has been requested.
  //
  // Must stay in sync with VRFCoordinator[_keyHash][this]
  mapping(bytes32 => uint256) /* keyHash */ /* 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) {
    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: @openzeppelin/contracts/utils/structs/EnumerableSet.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/structs/EnumerableSet.sol)

pragma solidity ^0.8.0;

/**
 * @dev Library for managing
 * https://en.wikipedia.org/wiki/Set_(abstract_data_type)[sets] of primitive
 * types.
 *
 * Sets have the following properties:
 *
 * - Elements are added, removed, and checked for existence in constant time
 * (O(1)).
 * - Elements are enumerated in O(n). No guarantees are made on the ordering.
 *
 * ```
 * contract Example {
 *     // Add the library methods
 *     using EnumerableSet for EnumerableSet.AddressSet;
 *
 *     // Declare a set state variable
 *     EnumerableSet.AddressSet private mySet;
 * }
 * ```
 *
 * As of v3.3.0, sets of type `bytes32` (`Bytes32Set`), `address` (`AddressSet`)
 * and `uint256` (`UintSet`) are supported.
 */
library EnumerableSet {
    // To implement this library for multiple types with as little code
    // repetition as possible, we write it in terms of a generic Set type with
    // bytes32 values.
    // The Set implementation uses private functions, and user-facing
    // implementations (such as AddressSet) are just wrappers around the
    // underlying Set.
    // This means that we can only create new EnumerableSets for types that fit
    // in bytes32.

    struct Set {
        // Storage of set values
        bytes32[] _values;
        // Position of the value in the `values` array, plus 1 because index 0
        // means a value is not in the set.
        mapping(bytes32 => uint256) _indexes;
    }

    /**
     * @dev Add a value to a set. O(1).
     *
     * Returns true if the value was added to the set, that is if it was not
     * already present.
     */
    function _add(Set storage set, bytes32 value) private returns (bool) {
        if (!_contains(set, value)) {
            set._values.push(value);
            // The value is stored at length-1, but we add 1 to all indexes
            // and use 0 as a sentinel value
            set._indexes[value] = set._values.length;
            return true;
        } else {
            return false;
        }
    }

    /**
     * @dev Removes a value from a set. O(1).
     *
     * Returns true if the value was removed from the set, that is if it was
     * present.
     */
    function _remove(Set storage set, bytes32 value) private returns (bool) {
        // We read and store the value's index to prevent multiple reads from the same storage slot
        uint256 valueIndex = set._indexes[value];

        if (valueIndex != 0) {
            // Equivalent to contains(set, value)
            // To delete an element from the _values array in O(1), we swap the element to delete with the last one in
            // the array, and then remove the last element (sometimes called as 'swap and pop').
            // This modifies the order of the array, as noted in {at}.

            uint256 toDeleteIndex = valueIndex - 1;
            uint256 lastIndex = set._values.length - 1;

            if (lastIndex != toDeleteIndex) {
                bytes32 lastvalue = set._values[lastIndex];

                // Move the last value to the index where the value to delete is
                set._values[toDeleteIndex] = lastvalue;
                // Update the index for the moved value
                set._indexes[lastvalue] = valueIndex; // Replace lastvalue's index to valueIndex
            }

            // Delete the slot where the moved value was stored
            set._values.pop();

            // Delete the index for the deleted slot
            delete set._indexes[value];

            return true;
        } else {
            return false;
        }
    }

    /**
     * @dev Returns true if the value is in the set. O(1).
     */
    function _contains(Set storage set, bytes32 value) private view returns (bool) {
        return set._indexes[value] != 0;
    }

    /**
     * @dev Returns the number of values on the set. O(1).
     */
    function _length(Set storage set) private view returns (uint256) {
        return set._values.length;
    }

    /**
     * @dev Returns the value stored at position `index` in the set. O(1).
     *
     * Note that there are no guarantees on the ordering of values inside the
     * array, and it may change when more values are added or removed.
     *
     * Requirements:
     *
     * - `index` must be strictly less than {length}.
     */
    function _at(Set storage set, uint256 index) private view returns (bytes32) {
        return set._values[index];
    }

    /**
     * @dev Return the entire set in an array
     *
     * WARNING: This operation will copy the entire storage to memory, which can be quite expensive. This is designed
     * to mostly be used by view accessors that are queried without any gas fees. Developers should keep in mind that
     * this function has an unbounded cost, and using it as part of a state-changing function may render the function
     * uncallable if the set grows to a point where copying to memory consumes too much gas to fit in a block.
     */
    function _values(Set storage set) private view returns (bytes32[] memory) {
        return set._values;
    }

    // Bytes32Set

    struct Bytes32Set {
        Set _inner;
    }

    /**
     * @dev Add a value to a set. O(1).
     *
     * Returns true if the value was added to the set, that is if it was not
     * already present.
     */
    function add(Bytes32Set storage set, bytes32 value) internal returns (bool) {
        return _add(set._inner, value);
    }

    /**
     * @dev Removes a value from a set. O(1).
     *
     * Returns true if the value was removed from the set, that is if it was
     * present.
     */
    function remove(Bytes32Set storage set, bytes32 value) internal returns (bool) {
        return _remove(set._inner, value);
    }

    /**
     * @dev Returns true if the value is in the set. O(1).
     */
    function contains(Bytes32Set storage set, bytes32 value) internal view returns (bool) {
        return _contains(set._inner, value);
    }

    /**
     * @dev Returns the number of values in the set. O(1).
     */
    function length(Bytes32Set storage set) internal view returns (uint256) {
        return _length(set._inner);
    }

    /**
     * @dev Returns the value stored at position `index` in the set. O(1).
     *
     * Note that there are no guarantees on the ordering of values inside the
     * array, and it may change when more values are added or removed.
     *
     * Requirements:
     *
     * - `index` must be strictly less than {length}.
     */
    function at(Bytes32Set storage set, uint256 index) internal view returns (bytes32) {
        return _at(set._inner, index);
    }

    /**
     * @dev Return the entire set in an array
     *
     * WARNING: This operation will copy the entire storage to memory, which can be quite expensive. This is designed
     * to mostly be used by view accessors that are queried without any gas fees. Developers should keep in mind that
     * this function has an unbounded cost, and using it as part of a state-changing function may render the function
     * uncallable if the set grows to a point where copying to memory consumes too much gas to fit in a block.
     */
    function values(Bytes32Set storage set) internal view returns (bytes32[] memory) {
        return _values(set._inner);
    }

    // AddressSet

    struct AddressSet {
        Set _inner;
    }

    /**
     * @dev Add a value to a set. O(1).
     *
     * Returns true if the value was added to the set, that is if it was not
     * already present.
     */
    function add(AddressSet storage set, address value) internal returns (bool) {
        return _add(set._inner, bytes32(uint256(uint160(value))));
    }

    /**
     * @dev Removes a value from a set. O(1).
     *
     * Returns true if the value was removed from the set, that is if it was
     * present.
     */
    function remove(AddressSet storage set, address value) internal returns (bool) {
        return _remove(set._inner, bytes32(uint256(uint160(value))));
    }

    /**
     * @dev Returns true if the value is in the set. O(1).
     */
    function contains(AddressSet storage set, address value) internal view returns (bool) {
        return _contains(set._inner, bytes32(uint256(uint160(value))));
    }

    /**
     * @dev Returns the number of values in the set. O(1).
     */
    function length(AddressSet storage set) internal view returns (uint256) {
        return _length(set._inner);
    }

    /**
     * @dev Returns the value stored at position `index` in the set. O(1).
     *
     * Note that there are no guarantees on the ordering of values inside the
     * array, and it may change when more values are added or removed.
     *
     * Requirements:
     *
     * - `index` must be strictly less than {length}.
     */
    function at(AddressSet storage set, uint256 index) internal view returns (address) {
        return address(uint160(uint256(_at(set._inner, index))));
    }

    /**
     * @dev Return the entire set in an array
     *
     * WARNING: This operation will copy the entire storage to memory, which can be quite expensive. This is designed
     * to mostly be used by view accessors that are queried without any gas fees. Developers should keep in mind that
     * this function has an unbounded cost, and using it as part of a state-changing function may render the function
     * uncallable if the set grows to a point where copying to memory consumes too much gas to fit in a block.
     */
    function values(AddressSet storage set) internal view returns (address[] memory) {
        bytes32[] memory store = _values(set._inner);
        address[] memory result;

        assembly {
            result := store
        }

        return result;
    }

    // UintSet

    struct UintSet {
        Set _inner;
    }

    /**
     * @dev Add a value to a set. O(1).
     *
     * Returns true if the value was added to the set, that is if it was not
     * already present.
     */
    function add(UintSet storage set, uint256 value) internal returns (bool) {
        return _add(set._inner, bytes32(value));
    }

    /**
     * @dev Removes a value from a set. O(1).
     *
     * Returns true if the value was removed from the set, that is if it was
     * present.
     */
    function remove(UintSet storage set, uint256 value) internal returns (bool) {
        return _remove(set._inner, bytes32(value));
    }

    /**
     * @dev Returns true if the value is in the set. O(1).
     */
    function contains(UintSet storage set, uint256 value) internal view returns (bool) {
        return _contains(set._inner, bytes32(value));
    }

    /**
     * @dev Returns the number of values on the set. O(1).
     */
    function length(UintSet storage set) internal view returns (uint256) {
        return _length(set._inner);
    }

    /**
     * @dev Returns the value stored at position `index` in the set. O(1).
     *
     * Note that there are no guarantees on the ordering of values inside the
     * array, and it may change when more values are added or removed.
     *
     * Requirements:
     *
     * - `index` must be strictly less than {length}.
     */
    function at(UintSet storage set, uint256 index) internal view returns (uint256) {
        return uint256(_at(set._inner, index));
    }

    /**
     * @dev Return the entire set in an array
     *
     * WARNING: This operation will copy the entire storage to memory, which can be quite expensive. This is designed
     * to mostly be used by view accessors that are queried without any gas fees. Developers should keep in mind that
     * this function has an unbounded cost, and using it as part of a state-changing function may render the function
     * uncallable if the set grows to a point where copying to memory consumes too much gas to fit in a block.
     */
    function values(UintSet storage set) internal view returns (uint256[] memory) {
        bytes32[] memory store = _values(set._inner);
        uint256[] memory result;

        assembly {
            result := store
        }

        return result;
    }
}

// File: @openzeppelin/contracts/utils/introspection/IERC165.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/introspection/IERC165.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC165 standard, as defined in the
 * https://eips.ethereum.org/EIPS/eip-165[EIP].
 *
 * Implementers can declare support of contract interfaces, which can then be
 * queried by others ({ERC165Checker}).
 *
 * For an implementation, see {ERC165}.
 */
interface IERC165 {
    /**
     * @dev Returns true if this contract implements the interface defined by
     * `interfaceId`. See the corresponding
     * https://eips.ethereum.org/EIPS/eip-165#how-interfaces-are-identified[EIP section]
     * to learn more about how these ids are created.
     *
     * This function call must use less than 30 000 gas.
     */
    function supportsInterface(bytes4 interfaceId) external view returns (bool);
}

// File: @openzeppelin/contracts/utils/Context.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/Context.sol)

pragma solidity ^0.8.0;

/**
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with meta-transactions the account sending and
 * paying for execution may not be the actual sender (as far as an application
 * is concerned).
 *
 * This contract is only required for intermediate, library-like contracts.
 */
abstract contract Context {
    function _msgSender() internal view virtual returns (address) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes calldata) {
        return msg.data;
    }
}

// File: @openzeppelin/contracts/token/ERC721/extensions/IERC721Enumerable.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.5.0) (token/ERC721/extensions/IERC721Enumerable.sol)

pragma solidity ^0.8.0;

import "../IERC721.sol";

/**
 * @title ERC-721 Non-Fungible Token Standard, optional enumeration extension
 * @dev See https://eips.ethereum.org/EIPS/eip-721
 */
interface IERC721Enumerable is IERC721 {
    /**
     * @dev Returns the total amount of tokens stored by the contract.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns a token ID owned by `owner` at a given `index` of its token list.
     * Use along with {balanceOf} to enumerate all of ``owner``'s tokens.
     */
    function tokenOfOwnerByIndex(address owner, uint256 index) external view returns (uint256);

    /**
     * @dev Returns a token ID at a given `index` of all the tokens stored by the contract.
     * Use along with {totalSupply} to enumerate all tokens.
     */
    function tokenByIndex(uint256 index) external view returns (uint256);
}

// File: @openzeppelin/contracts/utils/introspection/ERC165.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/introspection/ERC165.sol)

pragma solidity ^0.8.0;

import "./IERC165.sol";

/**
 * @dev Implementation of the {IERC165} interface.
 *
 * Contracts that want to implement ERC165 should inherit from this contract and override {supportsInterface} to check
 * for the additional interface id that will be supported. For example:
 *
 * ```solidity
 * function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
 *     return interfaceId == type(MyInterface).interfaceId || super.supportsInterface(interfaceId);
 * }
 * ```
 *
 * Alternatively, {ERC165Storage} provides an easier to use but more expensive implementation.
 */
abstract contract ERC165 is IERC165 {
    /**
     * @dev See {IERC165-supportsInterface}.
     */
    function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
        return interfaceId == type(IERC165).interfaceId;
    }
}

// File: @openzeppelin/contracts/utils/Strings.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/Strings.sol)

pragma solidity ^0.8.0;

/**
 * @dev String operations.
 */
library Strings {
    bytes16 private constant _HEX_SYMBOLS = "0123456789abcdef";

    /**
     * @dev Converts a `uint256` to its ASCII `string` decimal representation.
     */
    function toString(uint256 value) internal pure returns (string memory) {
        // Inspired by OraclizeAPI's implementation - MIT licence
        // https://github.com/oraclize/ethereum-api/blob/b42146b063c7d6ee1358846c198246239e9360e8/oraclizeAPI_0.4.25.sol

        if (value == 0) {
            return "0";
        }
        uint256 temp = value;
        uint256 digits;
        while (temp != 0) {
            digits++;
            temp /= 10;
        }
        bytes memory buffer = new bytes(digits);
        while (value != 0) {
            digits -= 1;
            buffer[digits] = bytes1(uint8(48 + uint256(value % 10)));
            value /= 10;
        }
        return string(buffer);
    }

    /**
     * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation.
     */
    function toHexString(uint256 value) internal pure returns (string memory) {
        if (value == 0) {
            return "0x00";
        }
        uint256 temp = value;
        uint256 length = 0;
        while (temp != 0) {
            length++;
            temp >>= 8;
        }
        return toHexString(value, length);
    }

    /**
     * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation with fixed length.
     */
    function toHexString(uint256 value, uint256 length) internal pure returns (string memory) {
        bytes memory buffer = new bytes(2 * length + 2);
        buffer[0] = "0";
        buffer[1] = "x";
        for (uint256 i = 2 * length + 1; i > 1; --i) {
            buffer[i] = _HEX_SYMBOLS[value & 0xf];
            value >>= 4;
        }
        require(value == 0, "Strings: hex length insufficient");
        return string(buffer);
    }
}

// File: @openzeppelin/contracts/token/ERC721/extensions/IERC721Metadata.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC721/extensions/IERC721Metadata.sol)

pragma solidity ^0.8.0;

import "../IERC721.sol";

/**
 * @title ERC-721 Non-Fungible Token Standard, optional metadata extension
 * @dev See https://eips.ethereum.org/EIPS/eip-721
 */
interface IERC721Metadata is IERC721 {
    /**
     * @dev Returns the token collection name.
     */
    function name() external view returns (string memory);

    /**
     * @dev Returns the token collection symbol.
     */
    function symbol() external view returns (string memory);

    /**
     * @dev Returns the Uniform Resource Identifier (URI) for `tokenId` token.
     */
    function tokenURI(uint256 tokenId) external view returns (string memory);
}

// File: @openzeppelin/contracts/token/ERC721/IERC721Receiver.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC721/IERC721Receiver.sol)

pragma solidity ^0.8.0;

/**
 * @title ERC721 token receiver interface
 * @dev Interface for any contract that wants to support safeTransfers
 * from ERC721 asset contracts.
 */
interface IERC721Receiver {
    /**
     * @dev Whenever an {IERC721} `tokenId` token is transferred to this contract via {IERC721-safeTransferFrom}
     * by `operator` from `from`, this function is called.
     *
     * It must return its Solidity selector to confirm the token transfer.
     * If any other value is returned or the interface is not implemented by the recipient, the transfer will be reverted.
     *
     * The selector can be obtained in Solidity with `IERC721.onERC721Received.selector`.
     */
    function onERC721Received(
        address operator,
        address from,
        uint256 tokenId,
        bytes calldata data
    ) external returns (bytes4);
}

// File: @chainlink/contracts/src/v0.8/VRFRequestIDBase.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

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/v0.8/interfaces/LinkTokenInterface.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

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/v0.8/vendor/ENSResolver.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

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

// File: @chainlink/contracts/src/v0.8/interfaces/PointerInterface.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

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

// File: @chainlink/contracts/src/v0.8/interfaces/OperatorInterface.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import "./OracleInterface.sol";
import "./ChainlinkRequestInterface.sol";

interface OperatorInterface is OracleInterface, ChainlinkRequestInterface {
  function operatorRequest(
    address sender,
    uint256 payment,
    bytes32 specId,
    bytes4 callbackFunctionId,
    uint256 nonce,
    uint256 dataVersion,
    bytes calldata data
  ) external;

  function fulfillOracleRequest2(
    bytes32 requestId,
    uint256 payment,
    address callbackAddress,
    bytes4 callbackFunctionId,
    uint256 expiration,
    bytes calldata data
  ) external returns (bool);

  function ownerTransferAndCall(
    address to,
    uint256 value,
    bytes calldata data
  ) external returns (bool success);

  function distributeFunds(address payable[] calldata receivers, uint256[] calldata amounts) external payable;

  function getAuthorizedSenders() external returns (address[] memory);

  function setAuthorizedSenders(address[] calldata senders) external;

  function getForwarder() external returns (address);
}

// File: @chainlink/contracts/src/v0.8/interfaces/ChainlinkRequestInterface.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

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/v0.8/interfaces/ENSInterface.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

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/v0.8/Chainlink.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

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 jobId The Job Specification ID
   * @param callbackAddr The callback address
   * @param callbackFunc The callback function signature
   * @return The initialized request
   */
  function initialize(
    Request memory self,
    bytes32 jobId,
    address callbackAddr,
    bytes4 callbackFunc
  ) internal pure returns (Chainlink.Request memory) {
    BufferChainlink.init(self.buf, defaultBufferSize);
    self.id = jobId;
    self.callbackAddress = callbackAddr;
    self.callbackFunctionId = callbackFunc;
    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/v0.8/interfaces/OracleInterface.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

interface OracleInterface {
  function fulfillOracleRequest(
    bytes32 requestId,
    uint256 payment,
    address callbackAddress,
    bytes4 callbackFunctionId,
    uint256 expiration,
    bytes32 data
  ) external returns (bool);

  function isAuthorizedSender(address node) external view returns (bool);

  function withdraw(address recipient, uint256 amount) external;

  function withdrawable() external view returns (uint256);
}

// File: @chainlink/contracts/src/v0.8/vendor/BufferChainlink.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

/**
 * @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;
    uint256 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, uint256 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, uint256 capacity) private pure {
    bytes memory oldbuf = buf.buf;
    init(buf, capacity);
    append(buf, oldbuf);
  }

  function max(uint256 a, uint256 b) private pure returns (uint256) {
    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,
    uint256 off,
    bytes memory data,
    uint256 len
  ) internal pure returns (buffer memory) {
    require(len <= data.length);

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

    uint256 dest;
    uint256 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
    unchecked {
      uint256 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,
    uint256 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,
    uint256 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,
    uint256 off,
    bytes32 data,
    uint256 len
  ) private pure returns (buffer memory) {
    if (len + off > buf.capacity) {
      resize(buf, (len + off) * 2);
    }

    unchecked {
      uint256 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,
    uint256 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,
    uint256 off,
    uint256 data,
    uint256 len
  ) private pure returns (buffer memory) {
    if (len + off > buf.capacity) {
      resize(buf, (len + off) * 2);
    }

    uint256 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,
    uint256 data,
    uint256 len
  ) internal pure returns (buffer memory) {
    return writeInt(buf, buf.buf.length, data, len);
  }
}

// File: @chainlink/contracts/src/v0.8/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 encodeFixedNumeric(BufferChainlink.buffer memory buf, uint8 major, uint64 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 {
      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 {
    if(value > 0xFFFFFFFFFFFFFFFF) {
      encodeBigNum(buf, value);
    } else {
      encodeFixedNumeric(buf, MAJOR_TYPE_INT, uint64(value));
    }
  }

  function encodeInt(BufferChainlink.buffer memory buf, int value) internal pure {
    if(value < -0x10000000000000000) {
      encodeSignedBigNum(buf, value);
    } else if(value > 0xFFFFFFFFFFFFFFFF) {
      encodeBigNum(buf, uint(value));
    } else if(value >= 0) {
      encodeFixedNumeric(buf, MAJOR_TYPE_INT, uint64(uint256(value)));
    } else {
      encodeFixedNumeric(buf, MAJOR_TYPE_NEGATIVE_INT, uint64(uint256(-1 - value)));
    }
  }

  function encodeBytes(BufferChainlink.buffer memory buf, bytes memory value) internal pure {
    encodeFixedNumeric(buf, MAJOR_TYPE_BYTES, uint64(value.length));
    buf.append(value);
  }

  function encodeBigNum(BufferChainlink.buffer memory buf, uint value) internal pure {
    buf.appendUint8(uint8((MAJOR_TYPE_TAG << 5) | TAG_TYPE_BIGNUM));
    encodeBytes(buf, abi.encode(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(uint256(-1 - input)));
  }

  function encodeString(BufferChainlink.buffer memory buf, string memory value) internal pure {
    encodeFixedNumeric(buf, MAJOR_TYPE_STRING, uint64(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);
  }
}