// File: /F/Dropbox/Code/CCNFT/contracts/PixlSoV.sol



//                                                                                                                                               
//  This is an ERC721 compliant smart contract for:
//   https://pix.ls
//
//  Bug Bounty:
//   Please see the details of our bug bounty program below.  
//   https://pix.ls/bug_bounty
//
//  Disclaimer:
//   We take the greatest of care when making our smart contracts but this is crypto and the future 
//   is always unknown. Even if it is exciting and full of wonderful possibilities, anything can happen,  
//   blockchains will evolve, vulnerabilities can arise, and markets can go up and down. Pix.ls and its  
//   owners accept no liability for any issues related to the use of this contract or any losses that may occur. 
//   This contract should be used for fun, art, and playing with collectables. It should not be used as an  
//   investment contract. Please see our full terms here: 
//   https://pix.ls/terms


// SPDX-License-Identifier: MIT
pragma solidity 0.8.7;
import "./base/ERC721Tradeable.sol";

contract PixlSoV is ERC721Tradeable 
{   
    // the mint marshal authorises all mints
    // if set to 0 then minting is disabled
    address private _mintMarshal;

    // only authorized burners can burn tokens
    // this allows nft game contracts to reclaim sov tokens when when minting game tokens
    mapping (address => bool) public isBurner; 

    constructor(address _owner, address _recovery, address _treasury,address _mmarshal, address _proxyRegistry) 
        ERC721Extended(_owner, _recovery, _treasury, "https://pix.ls/meta/sov/", _proxyRegistry) 
        ERC721("Bricks", unicode"⬢Bricks")    
    {        
        // set the mint marshal
        _mintMarshal = _mmarshal;    
           
    }

    

    
    /// MINTING

    // the mint marshal will need to approve all mints
    // set to 0 to disable minting
    function setMintMarshal(address newMarshal) external onlyOwner {
        _mintMarshal = newMarshal;
    }
    
    // ERC721 standard checks:
    // can't mint while the contract is paused (checked in _beforeTokenTransfer())
    // token id's can't already exist 
    // cant mint to address(0)
    // if 'to' refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.

    event Commission(address indexed earner, uint earned, uint tokenId); 

    // mint a single token
    function mint(address to, uint256 tokenId, uint256 expiry, address commissionTo, uint256 commissionWei, address feeTo, bytes memory marshalSignature) external payable reentrancyGuard   
    {       
        // CHECKS
        // check the details match what the marshal has signed
        validMint(_msgSender(), to, tokenId, msg.value, expiry, commissionTo, commissionWei, feeTo, marshalSignature);

        // EFFECTS
        _safeMint(to, tokenId);

        // INTERACTIONS
        // handle payments
        // the amounts have already been checked in hashMintDetails()

        //   security note: calls to a receivers below should only revert if insufficient gas is sent by the minter
        //   receivers can't be smart contracts IF we get them to sign a message before being added as a receiver
        //    - currently only EOA's (externally owned accounts) can sign a message on the ethereum network
        //    - smart contracts don't have a private key and can't sign a message
        //    - this means we should get all commission receivers to sign a message before they can receive commission

        uint _paidComm = 0;
        uint _paidFee = 0;

        // only pay out comm if address provided
        if(commissionTo!=address(0)){
            _paidComm = commissionWei;

            (bool success, ) = commissionTo.call{value:_paidComm}("");    
            require(success, "pay comm failed");        

            emit Commission(commissionTo, _paidComm, tokenId); 
        }

        // if no feeTo is provided then the fee will be retained by the contract
        if(feeTo!=address(0)){            
            _paidFee = msg.value - _paidComm;

            // we could pay the whole fee as commission above, so check for 0
            if(_paidFee>0){
                (bool success, ) = feeTo.call{value:_paidFee}("");    
                require(success, "pay fee failed");    
            }
        }

        // safety check  (should never be hit)
        assert(_paidComm + _paidFee <= msg.value);
    }

    function validMint(address minter, address to, uint256 tokenId, uint256 feeWei, uint256 expiry, address commissionTo, uint256 commissionWei, address feeTo, bytes memory marshalSignature) public view returns(bool)   
    {        
        // get the mint details hash 
        bytes32 _mint_hash = hashMintDetails(minter, to, tokenId, feeWei, expiry, commissionTo, commissionWei, feeTo);

        // check the marshal signed this mint hash
        require(_mintMarshal == signerOfHash(_mint_hash, marshalSignature), "bad hash");  

        // the details and signature are valid
        return true;
    }

    // this generates a hash of a mint details that can then be signed by the mint marshal
    function hashMintDetails(address minter, address to, uint256 tokenId, uint256 feeWei, uint256 expiry, address commissionTo, uint256 commissionWei, address feeTo) public view returns (bytes32){

        // check not already minted
        require(!_exists(tokenId), "already minted");

        // if the marshal is set to 0 then minting is disabled
        require(_mintMarshal!=address(0), "minting off");

        // the mint must not be expired yet
        require(block.timestamp < expiry, "expired");

        // if we must pay commission then we must have a valid amount
        if(commissionTo!=address(0)){           
            require(feeWei>0 && commissionWei>0 && commissionWei<=feeWei, "bad comm");
            require(commissionTo!=minter, "comm self");
        } 

        // if we must pay the fee onwards then we must have a valid fee
        if(feeTo!=address(0)){           
            require(feeWei>0, "feeTo no fee");
        }  

        // nonce is not required because mint's can't be replayed due to the tokenId being used 
        // also, the expiry timestamps are likely to change between all mints

        // now return the hash
        return keccak256(abi.encode(
            minter,
            to,
            tokenId,
            feeWei,
            expiry,
            commissionTo, 
            commissionWei, 
            feeTo,
            address(this)        // including the contract address prevents cross-contract replays  
        ));
    }

    /// BURNING

    // the contract owner can burn tokens it owns
    // or an authorized burner contract can burn any token
    // the contract owner can't burn someone elses tokens
    // normal users can't burn tokens

    // ERC721 standard checks:
    // can't burn while the contract is paused (checked in _beforeTokenTransfer())
    // the token id must exist
    
    // emitted when an authorization changes
    event BurnerSet(address indexed burner, bool auth);
   
    // changes a burners authorization
    function setBurner(address burner, bool authorized) external onlyOwner 
    { 
        isBurner[burner] = authorized;        
        emit BurnerSet(burner, authorized);        
    }

    // burn a single token
    function burn(uint256 tokenId, address belongsTo) external reentrancyGuard  
    {        
        address tokenOwner = ownerOf(tokenId);
        address contractOwner = owner();

        require(belongsTo == tokenOwner, "wrong owner");
        require(isBurner[_msgSender()]==true || 
                (tokenOwner == contractOwner && contractOwner == _msgSender() ), "not authed");
        _burn(tokenId);
    }
}


// File: /F/Dropbox/Code/CCNFT/contracts/base/ERC721Extended.sol



// SPDX-License-Identifier: MIT
pragma solidity 0.8.7;

import "@openzeppelin/contracts/token/ERC721/extensions/ERC721Enumerable.sol";
import "@openzeppelin/contracts/security/Pausable.sol";
import "../base/OwnableRecoverable.sol";

// ERC721Extended wraps multiple commonly used base contracts into a single contract
// 
// it includes:
//  ERC721 with Enumerable
//  contract ownership & recovery
//  contract pausing
//  base uri management
//  treasury 
//  proxy registry for opensea
//  ERC2981 

abstract contract ERC721Extended is ERC721Enumerable, Pausable, OwnableRecoverable 
{   
    // the treasure address that can make withdrawals from the contract balance
    address public treasury;

    // the base url used for all meta data 
    // used for tokens and for the contract
    string private _baseTokenURI;

    // support for ERC2981
    uint16 private _royaltyFee;
    address private _royaltyReciever;    

    // the opensea proxy registry contract (can be changed if this registry ever moves to a new contract)
    // 0xa5409ec958C83C3f309868babACA7c86DCB077c1  mainnet
    // 0xF57B2c51dED3A29e6891aba85459d600256Cf317  rinkeby
    // 0x0000000000000000000000000000000000000000  local
    address private _proxyRegistryAddress;
    
    constructor(address _owner, address _recovery, address _treasury, string memory _baseUri, address proxyRegistryAddress)  
    {
        // set the owner, recovery & treasury addresses
        transferOwnership(_owner);
        recovery = _recovery;
        treasury = _treasury;

        // set the meta base url
        _baseTokenURI = _baseUri;

        // set the open sea proxy registry address
        _proxyRegistryAddress = proxyRegistryAddress;

        // royalties
        _royaltyFee = 250;
        _royaltyReciever = _owner;
    }

    // used to stop a contract function from being reentrant-called 
    bool private _reentrancyLock = false;
    modifier reentrancyGuard {
        require(!_reentrancyLock, "reentrant");
 
        _reentrancyLock = true;
        _;
        _reentrancyLock = false;
    }


    /// PAUSING

    // only the contract owner can pause and unpause
    // can't pause if already paused
    // can't unpause if already unpaused
    // disables minting, burning, transfers (including marketplace accepted offers)

    function pause(bool on_off) external virtual onlyOwner {        
        if (on_off) _pause(); 
        else _unpause();      
    }
    // function unpause() external virtual onlyOwner {
    //     _unpause();
    // }

    // this hook is called by _mint, _burn & _transfer 
    // it allows us to block these actions while the contract is paused
    // also prevent transfers to the contract address
    function _beforeTokenTransfer(address from, address to, uint256 tokenId) internal virtual override {
        require(to != address(this), "to is contract");
        
        super._beforeTokenTransfer(from, to, tokenId);

        require(!paused(), "contract paused");
    }


    /// NAMES

    function setName(string memory name_, string memory symbol_) external onlyOwner {
        ERC721._name = name_;
        ERC721._symbol = symbol_;
    }

    /// TREASURY

    // can only be called by the contract owner
    // withdrawals can only be made to the treasury account

    // allows for a dedicated address to be used for withdrawals
    function setTreasury(address newTreasury) external onlyOwner { 
        require(newTreasury!=address(0), "0 address");
        treasury = newTreasury;
    }

    // funds can be withdrawn to the treasury account for safe keeping
    function treasuryOut(uint amount) external onlyOwner reentrancyGuard {
        
        // can withdraw any amount up to the account balance (0 will withdraw everything)
        uint balance = address(this).balance;
        if(amount == 0 || amount > balance) amount = balance;

        // make the withdrawal
        (bool success, ) = treasury.call{value:amount}("");
        require(success, "call fail");
    }
    
    // the owner can pay funds in at any time although this is not needed
    // perhaps the contract needs to hold a certain balance in future for some external requirement
    function treasuryIn() external payable onlyOwner {

    } 


    /// BASE URI

    // base uri is where the metadata lives
    // only the owner can change this

    function setBaseURI(string memory baseTokenURI) external onlyOwner {
        _baseTokenURI = baseTokenURI;
    }
    function _baseURI() internal view virtual override returns (string memory) {
        return _baseTokenURI;
    }
    function contractURI() public view returns (string memory) {
        return bytes(_baseTokenURI).length > 0 ? string(abi.encodePacked(_baseTokenURI, "contract")) : "";
    }


    /// PROXY REGISTRY

    // registers a proxy address for OpenSea or others
    // can only be changed by the contract owner
    // setting address to 0 will disable the proxy 

    function setProxyRegistry(address proxyRegistry) external onlyOwner { 

        // check the contract address is correct (will revert if not)
        if(proxyRegistry!= address(0)) {
            ProxyRegistry(proxyRegistry).proxies(address(0));
        }

        _proxyRegistryAddress = proxyRegistry;    
    }

    // this override allows us to whitelist user's OpenSea proxy accounts to enable gas-less listings
    function isApprovedForAll(address token_owner, address operator) public view override returns (bool)
    {
        // whitelist OpenSea proxy contract for easy trading.
        if(_proxyRegistryAddress!= address(0)) {
            ProxyRegistry proxyRegistry = ProxyRegistry(_proxyRegistryAddress);
            if (address(proxyRegistry.proxies(token_owner)) == operator) {
                return true;
            }
        }

        return super.isApprovedForAll(token_owner, operator);
    }


    /// ERC2981 support

    function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
        return interfaceId == 0x2a55205a  // ERC2981
               || super.supportsInterface(interfaceId);
    }

    function royaltyInfo(uint256, uint256 salePrice) external view returns (address receiver, uint256 royaltyAmount)
    {
        return (_royaltyReciever, (salePrice * _royaltyFee) / 10000);
    }

    // the royalties fee is set in basis points (eg. 250 basis points = 2.5%)
    function setRoyalties(address newReceiver, uint16 basisPoints) external onlyOwner {
        require(basisPoints <= 10000);
        _royaltyReciever = newReceiver;
        _royaltyFee = basisPoints;
    }

}

// used to whitelist proxy accounts of OpenSea users so that they are automatically able to trade any item on OpenSea
contract OwnableDelegateProxy {}
contract ProxyRegistry {
    mapping(address => OwnableDelegateProxy) public proxies;
} 

// File: /F/Dropbox/Code/CCNFT/contracts/base/ERC721Tradeable.sol



// SPDX-License-Identifier: MIT
pragma solidity 0.8.7;

import "../base/ERC721Extended.sol";

// ERC721Extended wraps multiple commonly used base contracts into a single contract
// 
// it includes:
//  ERC721 with Enumerable
//  contract ownership & recovery
//  contract pausing
//  base uri management
//  treasury 
//  proxy registry for opensea
//  ERC2981 
//  maker/taker off-chain trading system

abstract contract ERC721Tradeable is ERC721Extended 
{   
    // pausing the market disables the built-in maker/taker offer system 
    // it does not affect normal ERC721 transfers 
    bool public marketPaused;

    // the marketplace fee for any internal paid trades (stored in basis points eg. 250 = 2.5% fee) 
    uint16 public marketFee;

    // the marketplace witness is used to validate marketplace offers 
    address private _marketWitness;

    // offer that can no longer be used any more
    mapping (bytes32 => bool) private _cancelledOrCompletedOffers;

    constructor(){
        
        // market starts disabled
        marketPaused = true;       
        marketFee = 250; 
    }


    /// MARKETPLACE

    // this contract includes a maker / taker offerplace
    // (similar to those seen in OpenSea, 0x Protocol and other NFT projects) 
    //
    // offers are made by makers off-chain and filled by callers on-chain
    // makers do this by signing their offer with their wallet 
    // smart contracts can't be makers because they can't sign messages
    // if a witness address is set then it must sign the offer hash too (eg. the website marketplace)

    // there are two types of offers depending on whether the maker specifies a taker in their offer:
    // maker / taker       (peer-to-peer offer:  two users agreeing to trade items)
    // maker / no taker    (open offer:  one user listing their items in the marketplace)

    // if eth is paid then it will always be on the taker side (the maker never pays eth in this simplified model)
    // a market fee is charged if eth is paid
    // trading tokens with no eth is free and no fee is deducted

    // allowed exchanges:

    //   maker tokens  > <  eth                          (maker sells their tokens to anyone)
    //   maker tokens  >                                 (maker gives their tokens away to anyone)

    //   maker tokens  >    taker                        (maker gives their tokens to a specific taker)
    //   maker tokens  > <  taker tokens                     .. for specific tokens back
    //   maker tokens  > <  taker tokens & eth               .. for specific tokens and eth back 
    //   maker tokens  > <  taker eth                        .. for eth only

    //   maker           <  taker tokens                 (taker gives their tokens to the maker)
    //   maker           <  taker tokens & eth               .. and with eth    

    event OfferAccepted(bytes32 indexed hash, address indexed maker, address indexed taker, uint[] makerIds, uint[] takerIds, uint takerWei, uint marketFee);    
    event OfferCancelled(bytes32 indexed hash);
    
    struct Offer {
        address maker;
        address taker;
        uint256[] makerIds;        
        uint256[] takerIds;
        uint256 takerWei;
        uint256 expiry;
        uint256 nonce;
    }

    // pausing the market will stop offers from being able to be accepted (they can still be generated or cancelled)
    function pauseMarket(bool pauseTrading) external onlyOwner {
        marketPaused = pauseTrading;
    }

    // the market fee is set in basis points (eg. 250 basis points = 2.5%)
    function setMarketFee(uint16 basisPoints) external onlyOwner {
        require(basisPoints <= 10000);
        marketFee = basisPoints;
    }

    // if a market witness is set then it will need to sign all offers too (set to 0 to disable)
    function setMarketWitness(address newWitness) external onlyOwner {
        _marketWitness = newWitness;
    }

    // recovers the signer address from a hash and signature
    function signerOfHash(bytes32 _hash, bytes memory signature) public pure returns (address signer){
        require(signature.length == 65, "sig wrong length");

        bytes32 geth_modified_hash = keccak256(abi.encodePacked("\x19Ethereum Signed Message:\n32", _hash));
        bytes32 r;
        bytes32 s;
        uint8 v;

        assembly {
            r := mload(add(signature, 32))
            s := mload(add(signature, 64))
            v := byte(0, mload(add(signature, 96)))
        }

        if (v < 27) {
            v += 27;
        }

        require(v == 27 || v == 28, "bad sig v");

        return ecrecover(geth_modified_hash, v, r, s);
    }
 

    // this generates a hash of an offer that can then be signed by a maker
    // the offer has to have basic validity before it can be hashed
    // if checking ids then the tokens need to be owned by the parties too 
    function hashOffer(Offer memory offer, bool checkIds) public view returns (bytes32){

        // the maker can't be 0
        require(offer.maker!=address(0), "maker is 0");

        // maker and taker can't be the same
        require(offer.maker!=offer.taker, "same maker / taker");

        // the offer must not be expired yet
        require(block.timestamp < offer.expiry, "expired");

        // token id must be in the offer
        require(offer.makerIds.length>0 || offer.takerIds.length>0, "no ids");

        // if checking ids then maker must own the maker token ids
        if(checkIds){
            for(uint i=0; i<offer.makerIds.length; i++){
                require(ownerOf(offer.makerIds[i])==offer.maker, "bad maker ids");
            }
        }

        // if no taker has been specified (open offer - i.e. typical marketplace listing)
        if(offer.taker==address(0)){

            // then there can't be taker token ids in the offer
            require(offer.takerIds.length==0, "taker ids with no taker");
        }

        // if a taker has been specified (peer-to-peer offer - i.e. direct trade between two users)
        else{

            if(checkIds){
                // then the taker must own all the taker token ids   
                for(uint i=0; i<offer.takerIds.length; i++){
                    require(ownerOf(offer.takerIds[i])==offer.taker, "bad taker ids");
                }
            }
        }

        // now return the hash
        return keccak256(abi.encode(
            offer.maker,
            offer.taker,
            keccak256(abi.encodePacked(offer.makerIds)),            
            keccak256(abi.encodePacked(offer.takerIds)),
            offer.takerWei,
            offer.expiry,
            offer.nonce,
            address(this)        // including the contract address prevents cross-contract replays  
        ));
    }

    // an offer is valid if:
    //  it's maker / taker details are valid 
    //  it has been signed by the maker
    //  it has not been cancelled or completed yet
    //  the parties own their tokens (if checking ids)
    //  the witness has signed it (if witnessing is enabled)
    //  the trade is valid (if requested)
    function validOffer(Offer memory offer, bytes memory signature, bytes memory witnessSignature, bool checkIds, bool checkTradeValid, uint checkValue) external view returns (bool){

        // will revert if the offer or signer is not valid or checks fail
        bytes32 _offer_hash = _getValidOfferHash(offer, signature, checkIds, checkTradeValid, checkValue);

        // check the witness if needed
        _validWitness(_offer_hash, witnessSignature);

        return true;
    }

    // if a market witness is set then they need to sign the offer hash too
    function _validWitness(bytes32 _offer_hash, bytes memory witnessSignature) internal view {
        if(_marketWitness!=address(0)){       
            require(_marketWitness == signerOfHash(_offer_hash, witnessSignature), "wrong witness");  
        }
    }

    // gets the hash of an offer and checks that it has been signed by the maker
    function _getValidOfferHash(Offer memory offer, bytes memory signature, bool checkIds, bool checkTradeValid, uint checkValue) internal view returns (bytes32){

        // get the offer signer 
        bytes32 _offer_hash = hashOffer(offer, checkIds);
        address _signer = signerOfHash(_offer_hash, signature);
        
        // the signer must be the maker
        require(offer.maker==_signer, "maker not signer");
        
        // the offer can't be cancelled or completed already
        require(_cancelledOrCompletedOffers[_offer_hash]!=true, "offer cancelled or completed");

        // if checking the trade then we need to check the taker side too
        if(checkTradeValid){

            address caller = _msgSender();

            // no trading when paused
            require(!marketPaused, "marketplace paused");

            // caller can't be the maker
            require(caller!=offer.maker, "caller is the maker");

            // if there is a taker specified then they must be the caller
            require(caller==offer.taker || offer.taker==address(0), "caller not the taker");

            // check the correct wei has been provided by the taker (can be 0)
            require(checkValue==offer.takerWei, "wrong payment sent");
        }

        return _offer_hash;
    }
      
    
    // (gas: these functions can run out of gas if too many id's are provided
    //       not limiting them here because block gas limits change over time and we don't know what they will be in future)

    // stops the offer hash from being usable in future
    // can only be cancelled by the maker or the contract owner    
    function cancelOffer(Offer memory offer) external {
        address caller = _msgSender();
        require(caller == offer.maker || caller == owner(), "caller not maker or contract owner");

        // get the offer hash 
        bytes32 _offer_hash = hashOffer(offer, false);
                
        // set the offer hash as cancelled
        _cancelledOrCompletedOffers[_offer_hash]=true;
    
        emit OfferCancelled(_offer_hash);       
    }

    // fills an offer
    
    // offers can't be traded when the market is paused or the contract is paused
    // offers must be valid and signed by the maker 
    // the caller has to be the taker or can be an unknown party if no taker is set
    // eth may or may not be required by the offer
    // tokens must belong to the makers and takers

    function acceptOffer(Offer memory offer, bytes memory signature, bytes memory witnessSignature) external payable reentrancyGuard {
        
        // CHECKS
        
        // will revert if the offer or signer is not valid 
        // will also check token ids to make sure they belong to the parties
        // will check the caller and eth matches the offer taker details 
        bytes32 _offer_hash = _getValidOfferHash(offer, signature, true, true, msg.value);
       
        // check the witness if needed
        _validWitness(_offer_hash, witnessSignature);
       
        // EFFECTS

        address caller = _msgSender();

        // transfer the maker tokens to the caller
        for(uint i=0; i<offer.makerIds.length; i++){
             _safeTransfer(offer.maker, caller, offer.makerIds[i], "");
        }

        // transfer the taker tokens to the maker 
        for(uint i=0; i<offer.takerIds.length; i++){
             _safeTransfer(caller, offer.maker, offer.takerIds[i], "");
        }

        // set the offer as completed (stops the offer from being reused)
        _cancelledOrCompletedOffers[_offer_hash]=true;

        // INTERACTIONS

        // transfer the payment if one is present
        uint _fee = 0;
        if(msg.value>0){

            // calculate the marketplace fee (stored as basis points)
            // eg. 250 basis points is 2.5%  (250/10000) 
            _fee = msg.value * marketFee / 10000;
            uint _earned = msg.value - _fee;

            // safety check (should never be hit)
            assert(_earned<= msg.value && _fee+_earned==msg.value);
            
            // send the payment to the maker
            //   security note: calls to a maker should only revert if insufficient gas is sent by the caller/taker
            //   makers can't be smart contracts because makers need to sign the offer hash for us
            //    - currently only EOA's (externally owned accounts) can sign a message on the ethereum network
            //    - smart contracts don't have a private key and can't sign a message, so they can't be makers here
            //    - offers for specific makers can be blacklisted in the marketplace if required

            (bool success, ) = offer.maker.call{value:_earned}("");    
            require(success, "payment to maker failed");            
        }

        emit OfferAccepted(_offer_hash, offer.maker, caller, offer.makerIds, offer.takerIds, offer.takerWei, _fee);
    } 

}

// File: /F/Dropbox/Code/CCNFT/contracts/base/OwnableRecoverable.sol



// SPDX-License-Identifier: MIT

pragma solidity 0.8.7;

import "@openzeppelin/contracts/utils/Context.sol";
/**
 * This is a modified version of the standard OpenZeppelin Ownable contract that allows for a recovery address to be used to recover ownership
 * 
 * 
 * @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 OwnableRecoverable is Context {
    address private _owner;

    // the recovery address can be used to recover ownership if the owner wallet is ever lost
    // it should be a cold-storage wallet stored in a vault and never used for any other operation
    // it should be set in the parent constructor
    // if ownership moves to a new organization then the recovery address should be moved too
    address public recovery;

    // initializes the contract setting the deployer as the initial owner.
    constructor () {
        _setOwner(_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(), "caller not owner");
        _;
    }

    modifier onlyOwnerOrRecovery() {
        require(_msgSender() == owner() || _msgSender() == recovery, "caller not owner/recovery");
        _;
    }

    /**
     * @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 onlyOwnerOrRecovery {
        require(newOwner != address(0), "cant use 0 addr");
        _setOwner(newOwner);
    }

    function _setOwner(address newOwner) private {
        _owner = newOwner;
    }   

    // the recovery address can be changed by the owner or the recovery address
    function setRecovery(address newRecovery) public virtual onlyOwnerOrRecovery {   
        require(newRecovery != address(0), "cant use 0 addr");
        recovery = newRecovery;
    }
    

}

// File: @openzeppelin/contracts/security/Pausable.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

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

/**
 * @dev Contract module which allows children to implement an emergency stop
 * mechanism that can be triggered by an authorized account.
 *
 * This module is used through inheritance. It will make available the
 * modifiers `whenNotPaused` and `whenPaused`, which can be applied to
 * the functions of your contract. Note that they will not be pausable by
 * simply including this module, only once the modifiers are put in place.
 */
abstract contract Pausable is Context {
    /**
     * @dev Emitted when the pause is triggered by `account`.
     */
    event Paused(address account);

    /**
     * @dev Emitted when the pause is lifted by `account`.
     */
    event Unpaused(address account);

    bool private _paused;

    /**
     * @dev Initializes the contract in unpaused state.
     */
    constructor() {
        _paused = false;
    }

    /**
     * @dev Returns true if the contract is paused, and false otherwise.
     */
    function paused() public view virtual returns (bool) {
        return _paused;
    }

    /**
     * @dev Modifier to make a function callable only when the contract is not paused.
     *
     * Requirements:
     *
     * - The contract must not be paused.
     */
    modifier whenNotPaused() {
        require(!paused(), "Pausable: paused");
        _;
    }

    /**
     * @dev Modifier to make a function callable only when the contract is paused.
     *
     * Requirements:
     *
     * - The contract must be paused.
     */
    modifier whenPaused() {
        require(paused(), "Pausable: not paused");
        _;
    }

    /**
     * @dev Triggers stopped state.
     *
     * Requirements:
     *
     * - The contract must not be paused.
     */
    function _pause() internal virtual whenNotPaused {
        _paused = true;
        emit Paused(_msgSender());
    }

    /**
     * @dev Returns to normal state.
     *
     * Requirements:
     *
     * - The contract must be paused.
     */
    function _unpause() internal virtual whenPaused {
        _paused = false;
        emit Unpaused(_msgSender());
    }
}

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



// SPDX-License-Identifier: MIT

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 internal _name;

    // Token symbol
    string internal _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 {
        require(operator != _msgSender(), "ERC721: approve to caller");

        _operatorApprovals[_msgSender()][operator] = approved;
        emit ApprovalForAll(_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);
    }

    /**
     * @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);
    }

    /**
     * @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 of token that is not own");
        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);
    }

    /**
     * @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 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 {}
}

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



// SPDX-License-Identifier: MIT

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/token/ERC721/IERC721Receiver.sol



// SPDX-License-Identifier: MIT

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



// SPDX-License-Identifier: MIT

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/extensions/IERC721Enumerable.sol



// SPDX-License-Identifier: MIT

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 tokenId);

    /**
     * @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/token/ERC721/extensions/IERC721Metadata.sol



// SPDX-License-Identifier: MIT

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/utils/Address.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @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
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize, which returns 0 for contracts in
        // construction, since the code is only stored at the end of the
        // constructor execution.

        uint256 size;
        assembly {
            size := extcodesize(account)
        }
        return size > 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/Context.sol



// SPDX-License-Identifier: MIT

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/utils/Strings.sol



// SPDX-License-Identifier: MIT

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/utils/introspection/ERC165.sol



// SPDX-License-Identifier: MIT

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/introspection/IERC165.sol



// SPDX-License-Identifier: MIT

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);
}