// File: contracts/Edworm.sol



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

import '@openzeppelin/contracts/token/ERC721/ERC721.sol';
import '@openzeppelin/contracts/token/ERC721/extensions/ERC721Enumerable.sol';

import '@openzeppelin/contracts/access/Ownable.sol';
import '@openzeppelin/contracts/utils/Counters.sol';
import '@openzeppelin/contracts/utils/Strings.sol';

import 'base64-sol/base64.sol';

// In memory of my sweet cat Edwin. I told him he could live forever and now he can.

contract Edworm is Ownable, ERC721Enumerable {
	using Counters for Counters.Counter;
	using Strings for uint256;
	Counters.Counter private _tokenIdTracker;

	// Truth:
	string public constant R = 'Healing the world with comedy. Making a literal difference metaphorically.';

	// can the worm be released
	bool public hasItBegun = false;

	// the true cost is priceless
	uint public priceToRelease = 6.0 ether;

	// art & meta stuff
	mapping(bytes8 => string) meta;
	mapping(bytes8 => string) svg;
	bytes8[] svg0rig;
	bytes8[] svgHolo;

	//
	constructor() ERC721('Edworm', 'WORM') {
		//
		svg[
			'head'
		] = "<svg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 346 346' stroke-linecap='round' stroke-linejoin='round'>";
		svg[
			'font'
		] = "<style type='text/css'>@font-face { font-family: 'COMPUTER Robot'; font-weight: normal; src: url(data:application/font-woff2;charset=utf-8;base64,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) format('woff2'); }</style>";
		svg[
			'defs'
		] = "<defs><linearGradient id='_overlay' x1='0' x2='0' y1='0' y2='1'><stop offset='57%' stop-color='#080702'/><stop offset='71%' stop-color='#080702' stop-opacity='.75'/><stop offset='93%' stop-color='#080702' stop-opacity='0'/></linearGradient><linearGradient id='_text' x1='0' x2='0' y1='0' y2='1'><stop offset='30%' stop-color='#adff2f'/><stop offset='45%' stop-color='#adff2f'/><stop offset='77%' stop-color='#fff'/></linearGradient><clipPath id='_box'><path d='M0 0h346v346H0z'/></clipPath></defs>";
		svg[
			'back'
		] = "<g id='back' clip-path='url(#_box)'><path id='bg' fill='#080702' d='M0 0h346v346H0z'/><path id='lines' fill='none' stroke='#adff2f' stroke-width='6' d='M138 346V64M54.75 346L138 64M-22 335L138 64M-102 335L138 64M221.25 346L138 64M304.5 346L138 64M378 335L138 64M458 335L138 64M538 335L138 64M0 318h346M0 278h346M0 248.75l346 .13M346 226.74l-346-.16M346 209.3H0'/><path id='overlay' fill='url(#_overlay)' d='M0 0h346v346H0z'/></g>";
		svg[
			'text_a'
		] = "<g id='text' font-family='COMPUTER Robot' fill='url(#_text)'><text x='21.27' y='88.31' font-size='112'>T</text><text x='62.22' y='86.88' font-size='80'>HE</text><text x='22.05' y='138.22' font-size='80'>WOR</text><text x='149.27' y='139.68' font-size='112'>M</text><text x='24.22' y='162.16' fill='#ec008c' font-size='32'>#";
		svg[
			'text_b'
		] = "</text></g>";
		svg[
			'worm'
		] = "<g id='worm'><path fill='none' stroke='#ec008c' stroke-width='48' d='M65 247c6.25 30.96 49.37 33.85 59.7 4l10.06-29.09c11.46-33.11 58.26-33.2 69.83-.12l10.58 30.24c11.94 34.1 61.15 27.41 64.83-8.53.51-5 2.5-4.5-.86-151.5'/><path fill='none' stroke='#231f20' stroke-width='3.25' d='M276.92 104.27s-.32 3.57 2.92 3.57c3.25 0 2.92-3.9 2.92-3.9'/><path fill='#231f20' d='M271.59 97.16c1.33 0 2.42-1.1 2.43-2.43 0-1.34-1.1-2.43-2.43-2.44a2.46 2.46 0 00-2.44 2.43 2.48 2.48 0 002.44 2.44zm15.87-.25h.01a2.43 2.43 0 10-2.44-2.44 2.48 2.48 0 002.44 2.44z'/></g>";
		svg[
			'holo'
		] = "<g id='holo'><path fill='#080702' stroke='#adff2f' stroke-linecap='butt' stroke-width='3.3' d='M41.47 251.75c11.09 54.92 87.59 60.05 105.9 7.1l10.07-29.09c4.02-11.62 20.44-11.65 24.5-.04l10.58 30.23c20.48 58.54 105.04 47.69 111.35-14 .53-5.1 2.69-4.6-.73-154.5a24.01 24.01 0 00-48 1.1c3.3 144.1 1.49 143.6.99 148.5 0 0 0 0 0 0-1.05 10.2-14.92 12.72-18.3 3.05l-10.58-30.24c-19.09-54.54-96.28-54.4-115.17.2L102 243.17c-2.33 6.74-12.07 6.09-13.48-.9a24.01 24.01 0 00-47.06 9.49z'/><path fill='none' stroke='#adff2f' stroke-width='3.25' d='M276.92 104.27s-.32 3.57 2.92 3.57c3.25 0 2.92-3.9 2.92-3.9'/><path fill='#adff2f' d='M271.59 97.16c1.33 0 2.42-1.1 2.43-2.43 0-1.34-1.1-2.43-2.43-2.44a2.46 2.46 0 00-2.44 2.43 2.48 2.48 0 002.44 2.44zm15.87-.25h.01a2.43 2.43 0 10-2.44-2.44 2.48 2.48 0 002.44 2.44z'/></g>";
		svg[
			'tail'
		] = "</svg>";

		svg0rig = [
			//
			bytes8('head'),
			bytes8('font'),
			bytes8('defs'),
			bytes8('back'),
			bytes8('text_a'),
			bytes8('token_id'),
			bytes8('text_b'),
			bytes8('worm'),
			bytes8('tail')
		];

		svgHolo = [
			//
			bytes8('head'),
			bytes8('font'),
			bytes8('defs'),
			bytes8('back'),
			bytes8('text_a'),
			bytes8('token_id'),
			bytes8('text_b'),
			bytes8('holo'),
			bytes8('tail')
		];

		meta[
			'desc0rig'
		] = "The Worm is building a cult as he travels through the Ethereum blockchain. Help him on his journey by passing him along.";
		meta[
			'descHolo'
		] = "I've left this beautiful Hologram of myself as a memento of our special time together. Joining my cult was the best decision you ever made. You can never leave. Best Wishes. - The Worm.";
		meta['ext_url'] = "https://theworm.wtf/#";
	}

	//
	// managing
	//

	// withdraw balance
	function getPaid() public payable onlyOwner {
		require(payable(_msgSender()).send(address(this).balance));
	}

	function setPrice(uint256 price) external onlyOwner {
		priceToRelease = price;
	}

	function setBegun(bool yes) external onlyOwner {
		hasItBegun = yes;
	}

	function setArt(bytes8 key, string memory value) external onlyOwner {
		svg[key] = value;
	}

	function setLayers(bool isWorm, bytes8[] memory values) external onlyOwner {
		if (isWorm) {
			svg0rig = values;
		} else {
			svgHolo = values;
		}
	}

	function setMeta(bytes8 key, string memory value) external onlyOwner {
		meta[key] = value;
	}
	
	//
	// main
	//

	// don't release the worm
	function release() public payable {
		uint newTokenId = _tokenIdTracker.current();

		require(
			// ensure minting is only possible once it has begun
			hasItBegun == true,
			'TOO EARLY: it has not begun yet.'
		);

		require(
			// ensure only the 0riginal is ever minted
			newTokenId == 0,
			'TOO LATE: the 0riginal can only be minted once.'
		);

		require(
			// ensure the price was paid in full
			msg.value >= priceToRelease,
			'TOO POOR: send moar ether.'
		);

		mint(msg.sender);
	}

	//
	// transferring
	//

	function transferFrom(
		address from,
		address to,
		uint256 tokenId
	) public override {
		transferOverride(from, to, tokenId);
	}

	function safeTransferFrom(
		address from,
		address to,
		uint256 tokenId
	) public override {
		transferOverride(from, to, tokenId);
	}

	function safeTransferFrom(
		address from,
		address to,
		uint256 tokenId,
		bytes memory _data
	) public override {
		transferOverride(from, to, tokenId, _data);
	}

	function transferOverride(
		address from,
		address to,
		uint256 tokenId
	) internal {
		transferOverride(from, to, tokenId, '');
	}

	function transferOverride(
		address from,
		address to,
		uint256 tokenId,
		bytes memory _data
	) internal {
		//
		transfer(from, to, tokenId, _data);
		//
		mint(from);
	}

	// THIS is the main transfer function
	function propagate(address to) public {
		// enforce requirements
		transferOverride(msg.sender, to, 0);
	}

	// internal transfer
	function transfer(
		address from,
		address to,
		uint256 tokenId,
		bytes memory _data
	) internal {
		require(
			// require that the address isnt zero (not necessary) but
			// it's not about the gas, it's about sending a message
			to != address(0),
			'TOO BAD: cant burn me.'
		);

		require(
			// require that the token is the 0riginal
			tokenId == 0,
			'TOO BAD: only the 0riginal can be transferred.'
		);

		require(
			// require that the owner wasnt previously an owner
			balanceOf(to) == 0,
			'TOO BAD: you already had the 0riginal.'
		);

		require(
			// require because we overrode safeTransferFrom
			_isApprovedOrOwner(_msgSender(), tokenId),
			'ERC721: transfer caller is not owner nor approved'
		);

		_safeTransfer(from, to, tokenId, _data);
	}

	// internal mint a copy
	function mint(address to) internal {
		// do the mint
		uint newTokenId = _tokenIdTracker.current();
		_safeMint(to, newTokenId);

		// increment AFTER because starts at 0
		_tokenIdTracker.increment();
	}

	//
	// displaying
	//

	function getArt(uint256 _tokenId) public view returns (string memory) {
		string memory acc;
		bytes8[] memory layers;

		if (_tokenId == 0) {
			layers = svg0rig;
		} else {
			layers = svgHolo;
		}

		for (uint i = 0; i < layers.length; i++) {
			if (layers[i] == bytes8('token_id')) {
				acc = join(acc, _tokenId.toString());
			} else {
				acc = join(acc, svg[layers[i]]);
			}
		}

		return acc;
	}

	function join(string memory _a, string memory _b)
		internal
		pure
		returns (string memory result)
	{
		result = string(abi.encodePacked(bytes(_a), bytes(_b)));
	}

	function getMeta(uint256 _tokenId) public view returns (string memory) {
		string memory name;
		string memory desc;

		string memory image = Base64.encode(bytes(getArt(_tokenId)));

		if (_tokenId == 0) {
			name = 'The Worm';
			desc = meta['desc0rig'];
		} else {
			name = join('The Worm Hologram #', _tokenId.toString());
			desc = meta['descHolo'];
		}

		return string(abi.encodePacked(
			'data:application/json;base64,',
			Base64.encode(
				bytes(abi.encodePacked(
					'{',
						'"name": "', name, '",',
						'"description": "', desc, '",',
						'"image": "data:image/svg+xml;base64,', image, '",',
						'"external_url": "', meta['ext_url'], _tokenId.toString(), '"',
					'}'
				))
			)
		));
	}

	function tokenURI(uint256 _tokenId)
		public
		view
		override
		returns (string memory)
	{
		return getMeta(_tokenId);
	}

	// accept ether sent
	receive() external payable {}
}

// 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 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}. 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(to).onERC721Received.selector;
            } catch (bytes memory reason) {
                if (reason.length == 0) {
                    revert("ERC721: transfer to non ERC721Receiver implementer");
                } else {
                    // solhint-disable-next-line no-inline-assembly
                    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` 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 { }
}

// 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/access/Ownable.sol



// SPDX-License-Identifier: MIT

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 () {
        address msgSender = _msgSender();
        _owner = msgSender;
        emit OwnershipTransferred(address(0), 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 {
        emit OwnershipTransferred(_owner, address(0));
        _owner = 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");
        emit OwnershipTransferred(_owner, newOwner);
        _owner = newOwner;
    }
}

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



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @title Counters
 * @author Matt Condon (@shrugs)
 * @dev Provides counters that can only be incremented or decremented by one. 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;
        }
    }
}

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



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @dev String operations.
 */
library Strings {
    bytes16 private constant alphabet = "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] = alphabet[value & 0xf];
            value >>= 4;
        }
        require(value == 0, "Strings: hex length insufficient");
        return string(buffer);
    }

}

// File: base64-sol/base64.sol



// SPDX-License-Identifier: MIT

/// @title Base64
/// @author Brecht Devos - <brecht@loopring.org>
/// @notice Provides a function for encoding some bytes in base64
library Base64 {
    string internal constant TABLE = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/';

    function encode(bytes memory data) internal pure returns (string memory) {
        if (data.length == 0) return '';
        
        // load the table into memory
        string memory table = TABLE;

        // multiply by 4/3 rounded up
        uint256 encodedLen = 4 * ((data.length + 2) / 3);

        // add some extra buffer at the end required for the writing
        string memory result = new string(encodedLen + 32);

        assembly {
            // set the actual output length
            mstore(result, encodedLen)
            
            // prepare the lookup table
            let tablePtr := add(table, 1)
            
            // input ptr
            let dataPtr := data
            let endPtr := add(dataPtr, mload(data))
            
            // result ptr, jump over length
            let resultPtr := add(result, 32)
            
            // run over the input, 3 bytes at a time
            for {} lt(dataPtr, endPtr) {}
            {
               dataPtr := add(dataPtr, 3)
               
               // read 3 bytes
               let input := mload(dataPtr)
               
               // write 4 characters
               mstore(resultPtr, shl(248, mload(add(tablePtr, and(shr(18, input), 0x3F)))))
               resultPtr := add(resultPtr, 1)
               mstore(resultPtr, shl(248, mload(add(tablePtr, and(shr(12, input), 0x3F)))))
               resultPtr := add(resultPtr, 1)
               mstore(resultPtr, shl(248, mload(add(tablePtr, and(shr( 6, input), 0x3F)))))
               resultPtr := add(resultPtr, 1)
               mstore(resultPtr, shl(248, mload(add(tablePtr, and(        input,  0x3F)))))
               resultPtr := add(resultPtr, 1)
            }
            
            // padding with '='
            switch mod(mload(data), 3)
            case 1 { mstore(sub(resultPtr, 2), shl(240, 0x3d3d)) }
            case 2 { mstore(sub(resultPtr, 1), shl(248, 0x3d)) }
        }
        
        return result;
    }
}

// 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/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;
        // solhint-disable-next-line no-inline-assembly
        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");

        // solhint-disable-next-line avoid-low-level-calls, avoid-call-value
        (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");

        // solhint-disable-next-line avoid-low-level-calls
        (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");

        // solhint-disable-next-line avoid-low-level-calls
        (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");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.delegatecall(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    function _verifyCallResult(bool success, bytes memory returndata, string memory errorMessage) private 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

                // solhint-disable-next-line no-inline-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) {
        this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
        return msg.data;
    }
}

// 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);
}

// 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);
}