// SPDX-License-Identifier: MIT LICENSE

// OpenZeppelin Contracts v4.4.1 (utils/Context.sol)

pragma solidity ^0.8.0;

/**
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with meta-transactions the account sending and
 * paying for execution may not be the actual sender (as far as an application
 * is concerned).
 *
 * This contract is only required for intermediate, library-like contracts.
 */
abstract contract Context {
    function _msgSender() internal view virtual returns (address) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes calldata) {
        return msg.data;
    }
}

// File: @openzeppelin/contracts/access/Ownable.sol

// OpenZeppelin Contracts v4.4.1 (access/Ownable.sol)

pragma solidity ^0.8.0;

/**
 * @dev Contract module which provides a basic access control mechanism, where
 * there is an account (an owner) that can be granted exclusive access to
 * specific functions.
 *
 * By default, the owner account will be the one that deploys the contract. This
 * can later be changed with {transferOwnership}.
 *
 * This module is used through inheritance. It will make available the modifier
 * `onlyOwner`, which can be applied to your functions to restrict their use to
 * the owner.
 */
abstract contract Ownable is Context {
    address private _owner;

    event OwnershipTransferred(
        address indexed previousOwner,
        address indexed newOwner
    );

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    constructor() {
        _transferOwnership(_msgSender());
    }

    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view virtual returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        require(owner() == _msgSender(), "Ownable: caller is not the owner");
        _;
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions anymore. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby removing any functionality that is only available to the owner.
     */
    function renounceOwnership() public virtual onlyOwner {
        _transferOwnership(address(0));
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public virtual onlyOwner {
        require(
            newOwner != address(0),
            "Ownable: new owner is the zero address"
        );
        _transferOwnership(newOwner);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Internal function without access restriction.
     */
    function _transferOwnership(address newOwner) internal virtual {
        address oldOwner = _owner;
        _owner = newOwner;
        emit OwnershipTransferred(oldOwner, newOwner);
    }
}

// File: contracts/BGFVault.sol

// File: @openzeppelin/contracts/utils/introspection/IERC165.sol

pragma solidity ^0.8.0;

/**

 * @dev Interface of the ERC165 standard, as defined in the

 * https://eips.ethereum.org/EIPS/eip-165[EIP].

 *

 * Implementers can declare support of contract interfaces, which can then be

 * queried by others ({ERC165Checker}).

 *

 * For an implementation, see {ERC165}.

 */

interface IERC165 {
    /**

     * @dev Returns true if this contract implements the interface defined by

     * `interfaceId`. See the corresponding

     * https://eips.ethereum.org/EIPS/eip-165#how-interfaces-are-identified[EIP section]

     * to learn more about how these ids are created.

     *

     * This function call must use less than 30 000 gas.

     */

    function supportsInterface(bytes4 interfaceId) external view returns (bool);
}

// File: @openzeppelin/contracts/token/ERC721/IERC721.sol

pragma solidity ^0.8.0;

/**

 * @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/extensions/IERC721Enumerable.sol

pragma solidity ^0.8.0;

/**

 * @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/utils/introspection/ERC165.sol

pragma solidity ^0.8.0;

/**

 * @dev Implementation of the {IERC165} interface.

 *

 * Contracts that want to implement ERC165 should inherit from this contract and override {supportsInterface} to check

 * for the additional interface id that will be supported. For example:

 *

 * ```solidity

 * function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {

 *     return interfaceId == type(MyInterface).interfaceId || super.supportsInterface(interfaceId);

 * }

 * ```

 *

 * Alternatively, {ERC165Storage} provides an easier to use but more expensive implementation.

 */

abstract contract ERC165 is IERC165 {
    /**

     * @dev See {IERC165-supportsInterface}.

     */

    function supportsInterface(bytes4 interfaceId)
        public
        view
        virtual
        override
        returns (bool)
    {
        return interfaceId == type(IERC165).interfaceId;
    }
}

// File: @openzeppelin/contracts/utils/Strings.sol

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/Address.sol

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/token/ERC721/extensions/IERC721Metadata.sol

pragma solidity ^0.8.0;

/**

 * @title ERC-721 Non-Fungible Token Standard, optional metadata extension

 * @dev See https://eips.ethereum.org/EIPS/eip-721

 */

interface IERC721Metadata is IERC721 {
    /**

     * @dev Returns the token collection name.

     */

    function name() external view returns (string memory);

    /**

     * @dev Returns the token collection symbol.

     */

    function symbol() external view returns (string memory);

    /**

     * @dev Returns the Uniform Resource Identifier (URI) for `tokenId` token.

     */

    function tokenURI(uint256 tokenId) external view returns (string memory);
}

// File: @openzeppelin/contracts/token/ERC721/IERC721Receiver.sol

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/ERC721.sol

pragma solidity ^0.8.0;

/**

 * @dev Implementation of https://eips.ethereum.org/EIPS/eip-721[ERC721] Non-Fungible Token Standard, including

 * the Metadata extension, but not including the Enumerable extension, which is available separately as

 * {ERC721Enumerable}.

 */

contract ERC721 is Context, ERC165, IERC721, IERC721Metadata {
    using Address for address;

    using Strings for uint256;

    // Token name

    string private _name;

    // Token symbol

    string private _symbol;

    // Mapping from token ID to owner address

    mapping(uint256 => address) private _owners;

    // Mapping owner address to token count

    mapping(address => uint256) private _balances;

    // Mapping from token ID to approved address

    mapping(uint256 => address) private _tokenApprovals;

    // Mapping from owner to operator approvals

    mapping(address => mapping(address => bool)) private _operatorApprovals;

    /**

     * @dev Initializes the contract by setting a `name` and a `symbol` to the token collection.

     */

    constructor(string memory name_, string memory symbol_) {
        _name = name_;

        _symbol = symbol_;
    }

    /**

     * @dev See {IERC165-supportsInterface}.

     */

    function supportsInterface(bytes4 interfaceId)
        public
        view
        virtual
        override(ERC165, IERC165)
        returns (bool)
    {
        return
            interfaceId == type(IERC721).interfaceId ||
            interfaceId == type(IERC721Metadata).interfaceId ||
            super.supportsInterface(interfaceId);
    }

    /**

     * @dev See {IERC721-balanceOf}.

     */

    function balanceOf(address owner)
        public
        view
        virtual
        override
        returns (uint256)
    {
        require(
            owner != address(0),
            "ERC721: balance query for the zero address"
        );

        return _balances[owner];
    }

    /**

     * @dev See {IERC721-ownerOf}.

     */

    function ownerOf(uint256 tokenId)
        public
        view
        virtual
        override
        returns (address)
    {
        address owner = _owners[tokenId];

        require(
            owner != address(0),
            "ERC721: owner query for nonexistent token"
        );

        return owner;
    }

    /**

     * @dev See {IERC721Metadata-name}.

     */

    function name() public view virtual override returns (string memory) {
        return _name;
    }

    /**

     * @dev See {IERC721Metadata-symbol}.

     */

    function symbol() public view virtual override returns (string memory) {
        return _symbol;
    }

    /**

     * @dev See {IERC721Metadata-tokenURI}.

     */

    function tokenURI(uint256 tokenId)
        public
        view
        virtual
        override
        returns (string memory)
    {
        require(
            _exists(tokenId),
            "ERC721Metadata: URI query for nonexistent token"
        );

        string memory baseURI = _baseURI();

        return
            bytes(baseURI).length > 0
                ? string(abi.encodePacked(baseURI, tokenId.toString()))
                : "";
    }

    /**

     * @dev Base URI for computing {tokenURI}. If set, the resulting URI for each

     * token will be the concatenation of the `baseURI` and the `tokenId`. Empty

     * by default, can be overriden in child contracts.

     */

    function _baseURI() internal view virtual returns (string memory) {
        return "";
    }

    /**

     * @dev See {IERC721-approve}.

     */

    function approve(address to, uint256 tokenId) public virtual override {
        address owner = ERC721.ownerOf(tokenId);

        require(to != owner, "ERC721: approval to current owner");

        require(
            _msgSender() == owner || isApprovedForAll(owner, _msgSender()),
            "ERC721: approve caller is not owner nor approved for all"
        );

        _approve(to, tokenId);
    }

    /**

     * @dev See {IERC721-getApproved}.

     */

    function getApproved(uint256 tokenId)
        public
        view
        virtual
        override
        returns (address)
    {
        require(
            _exists(tokenId),
            "ERC721: approved query for nonexistent token"
        );

        return _tokenApprovals[tokenId];
    }

    /**

     * @dev See {IERC721-setApprovalForAll}.

     */

    function setApprovalForAll(address operator, bool approved)
        public
        virtual
        override
    {
        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/extensions/ERC721Enumerable.sol

pragma solidity ^0.8.0;

/**

 * @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();
    }
}

pragma solidity ^0.8.0;

interface HELLISHVAULT {
    function getBankBalance(address _address) external returns (uint256);
    function spendBalanceTowers(address _address, uint256 _amount) external;
}

contract BGFTOWERS is ERC721Enumerable, Ownable {
    using Strings for uint256;

    string public baseURI;
    string public baseExtension = "";
    uint256 public maxSupply = 600;
    uint256 public price = 800;
    bool public paused = true;
    address public bgfVault;

    HELLISHVAULT vaultContract;

    constructor() ERC721("Bad Girlfriend Project Towers", "BGFTOWERS") {}

    // internal
      function _baseURI() internal view virtual override returns (string memory) {
        return baseURI;
    }

    function setVaultAddress(address _address) public onlyOwner {
        bgfVault = _address;
        vaultContract = HELLISHVAULT(_address);
    }

    function mint() public {
        require(!paused, "Not allowed yet.");
        uint256 balance = vaultContract.getBankBalance(msg.sender);
        require(balance >= price, "Insufficient Balance.");
        uint256 supply = totalSupply();
        require(supply + 1 <= maxSupply, "Total supply would be reached.");
        vaultContract.spendBalanceTowers(msg.sender, price);
        _safeMint(msg.sender, supply + 1);
        if (supply + 1 == 100) {
            paused = true;
        }
        if (supply + 1 == 200) {
            paused = true;
        }
        if (supply + 1 == 300) {
            paused = true;
        }
        if (supply + 1 == 400) {
            paused = true;
        }
        if (supply + 1 == 500) {
            paused = true;
        }
    }

    function walletOfOwner(address _owner)
        public
        view
        returns (uint256[] memory)
    {
        uint256 ownerTokenCount = balanceOf(_owner);
        uint256[] memory tokenIds = new uint256[](ownerTokenCount);

        for (uint256 i; i < ownerTokenCount; i++) {
            tokenIds[i] = tokenOfOwnerByIndex(_owner, i);
        }

        return tokenIds;
    }

    function tokenURI(uint256 tokenId)
        public
        view
        virtual
        override
        returns (string memory)
    {
        require(_exists(tokenId), "Token doesn't exist.");

        string memory currentBaseURI = _baseURI();

        return
            bytes(currentBaseURI).length > 0
                ? string(
                    abi.encodePacked(
                        currentBaseURI,
                        tokenId.toString(),
                        baseExtension
                    )
                )
                : "";
    }

    // only owner
    function setBaseURI(string memory _newBaseURI) public onlyOwner {
        baseURI = _newBaseURI;
    }

    function setBaseExtension(string memory _newBaseExtension)
        public
        onlyOwner
    {
        baseExtension = _newBaseExtension;
    }

    function pause(bool _state) public onlyOwner {
        paused = _state;
    }

    function setPrice(uint256 _price) public onlyOwner {
        price = _price;
    }

    function withdraw() public payable onlyOwner {
        require(payable(msg.sender).send(address(this).balance));
    }
}