Ibis Chess Club

// SPDX-License-Identifier: MIT
// File: @openzeppelin/contracts/utils/cryptography/MerkleProof.sol


// OpenZeppelin Contracts (last updated v4.5.0) (utils/cryptography/MerkleProof.sol)

pragma solidity ^0.8.0;

/**
 * @dev These functions deal with verification of Merkle Trees proofs.
 *
 * The proofs can be generated using the JavaScript library
 * https://github.com/miguelmota/merkletreejs[merkletreejs].
 * Note: the hashing algorithm should be keccak256 and pair sorting should be enabled.
 *
 * See `test/utils/cryptography/MerkleProof.test.js` for some examples.
 */
library MerkleProof {
    /**
     * @dev Returns true if a `leaf` can be proved to be a part of a Merkle tree
     * defined by `root`. For this, a `proof` must be provided, containing
     * sibling hashes on the branch from the leaf to the root of the tree. Each
     * pair of leaves and each pair of pre-images are assumed to be sorted.
     */
    function verify(
        bytes32[] memory proof,
        bytes32 root,
        bytes32 leaf
    ) internal pure returns (bool) {
        return processProof(proof, leaf) == root;
    }

    /**
     * @dev Returns the rebuilt hash obtained by traversing a Merklee tree up
     * from `leaf` using `proof`. A `proof` is valid if and only if the rebuilt
     * hash matches the root of the tree. When processing the proof, the pairs
     * of leafs & pre-images are assumed to be sorted.
     *
     * _Available since v4.4._
     */
    function processProof(bytes32[] memory proof, bytes32 leaf) internal pure returns (bytes32) {
        bytes32 computedHash = leaf;
        for (uint256 i = 0; i < proof.length; i++) {
            bytes32 proofElement = proof[i];
            if (computedHash <= proofElement) {
                // Hash(current computed hash + current element of the proof)
                computedHash = _efficientHash(computedHash, proofElement);
            } else {
                // Hash(current element of the proof + current computed hash)
                computedHash = _efficientHash(proofElement, computedHash);
            }
        }
        return computedHash;
    }

    function _efficientHash(bytes32 a, bytes32 b) private pure returns (bytes32 value) {
        assembly {
            mstore(0x00, a)
            mstore(0x20, b)
            value := keccak256(0x00, 0x40)
        }
    }
}

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


// OpenZeppelin Contracts v4.4.1 (utils/Strings.sol)

pragma solidity ^0.8.0;

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

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

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

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

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

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


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


// OpenZeppelin Contracts (last updated v4.5.0) (utils/Address.sol)

pragma solidity ^0.8.1;

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

        return account.code.length > 0;
    }

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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


// OpenZeppelin Contracts v4.4.1 (token/ERC721/IERC721Receiver.sol)

pragma solidity ^0.8.0;

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

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


// OpenZeppelin Contracts v4.4.1 (utils/introspection/IERC165.sol)

pragma solidity ^0.8.0;

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

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


// OpenZeppelin Contracts v4.4.1 (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/token/ERC721/IERC721.sol


// OpenZeppelin Contracts v4.4.1 (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/IERC721Metadata.sol


// OpenZeppelin Contracts v4.4.1 (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/ERC721.sol


// OpenZeppelin Contracts (last updated v4.5.0) (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 {
        _setApprovalForAll(_msgSender(), operator, approved);
    }

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

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

        _transfer(from, to, tokenId);
    }

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

        _beforeTokenTransfer(from, to, tokenId);

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

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

        emit Transfer(from, to, tokenId);

        _afterTokenTransfer(from, to, tokenId);
    }

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

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

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

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

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

// File: IBISChessclub.sol


pragma solidity ^0.8.7;

abstract contract CATS {
    function balanceOf(address owner) external virtual view returns (uint256 balance);
}

abstract contract FLS {
    function balanceOf(address owner) external virtual view returns (uint256 balance);
}

contract IBISChessclub is ERC721, Ownable {
    CATS private cats;
    FLS private fls;

    using Strings for uint256;

    address catsAdress = 0x568a1f8554Edcea5CB5F94E463ac69A9C49c0A2d;
    address flsAddress = 0xf11B3a52e636dD04aa740cC97C5813CAAb0b75d0;

    uint256 public firstPawnId = 382;
    uint256 public firstKnightId = 748;
    uint256 public firstBishopId = 1196;
    uint256 public firstRookId = 1617;
    uint256 public firstQueenId = 2053;
    uint256 public firstKingId = 2517;
    uint256 public firstSpecialId = 2967;

    uint256 public MAX_SUPPLY_PAWNS = 366;
    uint256 public MAX_SUPPLY_KNIGHTS = 448;
    uint256 public MAX_SUPPLY_BISHOPS = 421;
    uint256 public MAX_SUPPLY_ROOKS = 436;
    uint256 public MAX_SUPPLY_QUEENS = 464;
    uint256 public MAX_SUPPLY_KINGS = 450;
    uint256 public MAX_SUPPLY_SPECIAL = 175;

    uint256 public numSpecial = 0;
    uint256 public numKings = 0;
    uint256 public numQueens = 0;
    uint256 public numRooks = 0;
    uint256 public numBishops = 0;
    uint256 public numKnights = 0;
    uint256 public numPawns = 0;

    uint256 public pawnPrice =     31400000000000000;
    uint256 public knightPrice =   42000000000000000;
    uint256 public bishopPrice =   69000000000000000;
    uint256 public rookPrice =     89000000000000000;
    uint256 public queenPrice =   111100000000000000;
    uint256 public kingPrice =    130000000000000000;
    uint256 public specialPrice = 210000000000000000;

    uint256 public saleState = 0; // 0 = no sale, 1 = freemint, 2 = presale, 3 = public sale

    string private baseURI;

    bytes32 public freeMintRoot = 0x2b97f8602f78fbab8ac7bb9fef77d88b04f5c2b152c727328ced917ffae3ca13;
    bytes32 public whitelistRoot;

    mapping(address => uint256) public whiteListTx;
    mapping(address => uint256) public freemintTx;

    enum ChessPiece { Pawn, Knight, Bishop, Rook, Queen, King, Special }

    constructor() ERC721("Ibis Chess Club", "IBIS") {
        baseURI = "http://ibis.mintthepieces.com/metadata/";

        cats = CATS(catsAdress);
        fls = FLS(flsAddress);
    }

    function setSaleStatus(uint256 _saleState) external onlyOwner {  // 0 = no sale, 1 = freemint, 2 = presale, 3 = public sale
        require(_saleState >= 0 && _saleState < 4, "No such sale state");
        saleState = _saleState;
    }

    function getPiecePrices() external view returns(uint256[7] memory prices) {
        return [pawnPrice, knightPrice, bishopPrice, rookPrice, queenPrice, kingPrice, specialPrice];
    }

    function reservePieces(uint256 amount) external onlyOwner {
        uint256 nonce = 0;
        uint256 rand;
        for (uint256 i = 0; i < amount; i++) {
            rand = uint256(keccak256(abi.encodePacked(block.timestamp, msg.sender, nonce))) % 100;
            if (rand < 14) {
                // pawn
                randomMintPiece(ChessPiece.Pawn, 1);
            } else if (rand < 29) {
                // knight
                randomMintPiece(ChessPiece.Knight, 1);
            } else if (rand < 44) {
                // bishop
                randomMintPiece(ChessPiece.Bishop, 1);
            } else if (rand < 60) {
                // rook
                randomMintPiece(ChessPiece.Rook, 1);
            } else if (rand < 78) {
                // queen
                randomMintPiece(ChessPiece.Queen, 1);
            } else if (rand < 93) {
                // king
                randomMintPiece(ChessPiece.King, 1);
            } else {
                // special
                randomMintPiece(ChessPiece.Special, 1);
            }
            nonce++;
        }
    }

    function setPiecePrices(uint256[] calldata prices) external onlyOwner {
        require(prices.length == 7, "Wrong number of parameters given");
        if (prices[0] > 0) {
            pawnPrice = prices[0];
        }
        if (prices[1] > 0) {
            knightPrice = prices[1];
        }
        if (prices[2] > 0) {
            bishopPrice = prices[2];
        }
        if (prices[3] > 0) {
            rookPrice = prices[3];
        }
        if (prices[4] > 0) {
            queenPrice = prices[4];
        }
        if (prices[5] > 0) {
            kingPrice = prices[5];
        }
        if (prices[6] > 0) {
            kingPrice = prices[6];
        }
    }

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

    function tokenURI(uint256 tokenId) public override view returns (string memory) {
        return bytes(baseURI).length > 0 ? string(abi.encodePacked(baseURI, tokenId.toString(), ".json")) : "";
    }

    // set new freemint root
    function setFreeMintRoot(bytes32 _root) external onlyOwner {
        freeMintRoot = _root;
    }

    // set new whitelist root
    function setWhitelistRoot(bytes32 _root) external onlyOwner {
        whitelistRoot = _root;
    }

    function setBaseURI(string memory uri) public onlyOwner {
        baseURI = uri;
    }

    // emergency claim function if someone forgets to claim their free token
    function ownerClaimToken(uint256 id) external onlyOwner {
        require(!_exists(id), "Token already exists");
        _safeMint(msg.sender, id);
    }

    function freeClaimMint(bytes32[] calldata proof, uint256[] calldata tokenIds) external {
        require(saleState == 1, "Free claim not available right now");
        require(freemintTx[msg.sender] == 0, "Already claimed your tokens");
        bytes32 node = keccak256(abi.encodePacked(msg.sender));       
        require(MerkleProof.verify(proof, freeMintRoot, node), "Address is not available for free claim mint");

        for (uint256 i = 0; i < tokenIds.length; i++) {
            require(!_exists(tokenIds[i]), "Token already claimed");
        }
        freemintTx[msg.sender] = 1;
        for (uint256 i = 0; i < tokenIds.length; i++) {
            _safeMint(msg.sender, tokenIds[i]);
        }
    }

    function whitelistMint(bytes32[] calldata proof, uint256 typeId) external payable {
        require(saleState == 2, "Whitelist minting closed");
        require(whiteListTx[msg.sender] == 0, "Already have minted during presale");
        require(hasEnoughTokensSingle(typeId), "Would exceed maximum supply of this piece");
        require(checkValueOne(typeId, msg.value), "Incorrect value sent");
        bytes32 node = keccak256(abi.encodePacked(msg.sender));
        require(MerkleProof.verify(proof, whitelistRoot, node), "Address is not on whitelist");

        whiteListTx[msg.sender] = 1;
        randomMintPiece(ChessPiece(typeId), 1);
    }

    function mintFlsCats(uint256 typeId) external payable {
        require(saleState == 2, "Whitelist minting closed");
        require(whiteListTx[msg.sender] == 0, "Already have minted during presale");
        require(hasEnoughTokensSingle(typeId), "Would exceed maximum supply of this piece");
        require(checkValueOne(typeId, msg.value), "Incorrect value sent");
        require(fls.balanceOf(msg.sender) > 0 || cats.balanceOf(msg.sender) > 0, "Address does not own a Stranger nor a Cat");

        whiteListTx[msg.sender] = 1;
        randomMintPiece(ChessPiece(typeId), 1);
    }

    function randomNumber(uint256 max, uint256 offset, uint256 nonce) private view returns(uint256) {
        uint256 rand = uint256(keccak256(abi.encodePacked(block.timestamp, msg.sender, nonce))) % max + offset;
        return rand;
    }

    function randomMintPiece(ChessPiece piece, uint256 amount) private {
        uint256 index;
        uint256 nonce = 0;

        if (piece == ChessPiece.Pawn) {
            for (uint256 i = 0; i < amount; i++) {
                nonce = randomNumber(MAX_SUPPLY_PAWNS, firstPawnId, nonce);
                index = randomNumber(MAX_SUPPLY_PAWNS, firstPawnId, nonce);
                while (_exists(index)) {
                    nonce++;
                    index = randomNumber(MAX_SUPPLY_PAWNS, firstPawnId, nonce);
                }
                numPawns++;
                _safeMint(msg.sender, index);
            }
        }

        if (piece == ChessPiece.Knight) {
            for (uint256 i = 0; i < amount; i++) {
                nonce = randomNumber(MAX_SUPPLY_KNIGHTS, firstKnightId, nonce);
                index = randomNumber(MAX_SUPPLY_KNIGHTS, firstKnightId, nonce);
                while (_exists(index)) {
                    nonce++;
                    index = randomNumber(MAX_SUPPLY_KNIGHTS, firstKnightId, nonce);
                }
                numKnights++;
                _safeMint(msg.sender, index);
            }
        }

        if (piece == ChessPiece.Bishop) {
            for (uint256 i = 0; i < amount; i++) {
                nonce = randomNumber(MAX_SUPPLY_BISHOPS, firstBishopId, nonce);
                index = randomNumber(MAX_SUPPLY_BISHOPS, firstBishopId, nonce);
                while (_exists(index)) {
                    nonce++;
                    index = randomNumber(MAX_SUPPLY_BISHOPS, firstBishopId, nonce);
                }
                numBishops++;
                _safeMint(msg.sender, index);
            }
        }

        if (piece == ChessPiece.Rook) {
            for (uint256 i = 0; i < amount; i++) {
                nonce = randomNumber(MAX_SUPPLY_ROOKS, firstRookId, nonce);
                index = randomNumber(MAX_SUPPLY_ROOKS, firstRookId, nonce);
                while (_exists(index)) {
                    nonce++;
                    index = randomNumber(MAX_SUPPLY_ROOKS, firstRookId, nonce);
                }
                numRooks++;
                _safeMint(msg.sender, index);
            }
        }

        if (piece == ChessPiece.Queen) {
            for (uint256 i = 0; i < amount; i++) {
                nonce = randomNumber(MAX_SUPPLY_QUEENS, firstQueenId, nonce);
                index = randomNumber(MAX_SUPPLY_QUEENS, firstQueenId, nonce);
                while (_exists(index)) {
                    nonce++;
                    index = randomNumber(MAX_SUPPLY_QUEENS, firstQueenId, nonce);
                }
                numQueens++;
                _safeMint(msg.sender, index);
            }
        }

        if (piece == ChessPiece.King) {
            for (uint256 i = 0; i < amount; i++) {
                nonce = randomNumber(MAX_SUPPLY_KINGS, firstKingId, nonce);
                index = randomNumber(MAX_SUPPLY_KINGS, firstKingId, nonce);
                while (_exists(index)) {
                    nonce++;
                    index = randomNumber(MAX_SUPPLY_KINGS, firstKingId, nonce);
                }
                numKings++;
                _safeMint(msg.sender, index);
            }
        }

        if (piece == ChessPiece.Special) {
            for (uint256 i = 0; i < amount; i++) {
                nonce = randomNumber(MAX_SUPPLY_SPECIAL, firstSpecialId, nonce);
                index = randomNumber(MAX_SUPPLY_SPECIAL, firstSpecialId, nonce);
                while (_exists(index)) {
                    nonce++;
                    index = randomNumber(MAX_SUPPLY_SPECIAL, firstSpecialId, nonce);
                }
                numSpecial++;
                _safeMint(msg.sender, index);
            }
        }
    }

    function hasEnoughTokensMultiple(uint256[] calldata ids) private view returns(bool) {
        return ids[0] + numPawns <= MAX_SUPPLY_PAWNS
                && ids[1] + numKnights <= MAX_SUPPLY_KNIGHTS 
                && ids[2] + numBishops <= MAX_SUPPLY_BISHOPS 
                && ids[3] + numRooks <= MAX_SUPPLY_ROOKS 
                && ids[4] + numQueens <= MAX_SUPPLY_QUEENS 
                && ids[5] + numKings <= MAX_SUPPLY_KINGS
                && ids[6] + numSpecial <= MAX_SUPPLY_SPECIAL;
    }

    function hasEnoughTokensSingle(uint256 typeId) private view returns(bool) {
        if (typeId == 0) {
            return numPawns + 1 <= MAX_SUPPLY_PAWNS;
        } else if (typeId == 1) {
            return numKnights + 1 <= MAX_SUPPLY_KNIGHTS;
        } else if (typeId == 2) {
            return numBishops + 1 <= MAX_SUPPLY_BISHOPS;
        } else if (typeId == 3) {
            return numRooks + 1 <= MAX_SUPPLY_ROOKS;
        } else if (typeId == 4) {
            return numQueens + 1 <= MAX_SUPPLY_QUEENS;
        } else if (typeId == 5) {
            return numKings + 1 <= MAX_SUPPLY_KINGS;
        } else {
            return numSpecial + 1 <= MAX_SUPPLY_SPECIAL;
        }
    }

    function checkValueMultiple(uint256[] calldata ids, uint256 value) private view returns(bool) {
        uint256 price = (ids[0] * pawnPrice) + (ids[1] * knightPrice) + (ids[2] * bishopPrice) + (ids[3] * rookPrice) + (ids[4] * queenPrice) + (ids[5] * kingPrice) + (ids[6] * specialPrice);
        return price == value;
    }

    function checkValueOne(uint256 typeId, uint256 value) private view returns(bool) {
        uint256 price;

        if (typeId == 0) {
            price = pawnPrice;
        } else if (typeId == 1) {
            price = knightPrice;
        } else if (typeId == 2) {
            price = bishopPrice;
        } else if (typeId == 3) {
            price = rookPrice;
        } else if (typeId == 4) {
            price = queenPrice;
        } else if (typeId == 5) {
            price = kingPrice;
        } else {
            price = specialPrice;
        }
        
        return price == value;
    }

    function publicMint(uint256[] calldata ids) external payable {
        require(saleState == 3, "Sale currently closed");
        require(checkValueMultiple(ids, msg.value), "Incorrect value sent");
        require(hasEnoughTokensMultiple(ids), "Order will exceed max number of tokens");


        if (ids[0] > 0) {
            randomMintPiece(ChessPiece.Pawn, ids[0]);
        }

        if (ids[1] > 0) {
            randomMintPiece(ChessPiece.Knight, ids[1]);
        }

        if (ids[2] > 0) {
            randomMintPiece(ChessPiece.Bishop, ids[2]);
        }

        if (ids[3] > 0) {
            randomMintPiece(ChessPiece.Rook, ids[3]);
        }

        if (ids[4] > 0) {
            randomMintPiece(ChessPiece.Queen, ids[4]);
        }
        
        if (ids[5] > 0) {
            randomMintPiece(ChessPiece.King, ids[5]);
        }

        if (ids[6] > 0) {
            randomMintPiece(ChessPiece.Special, ids[6]);
        }
    }

    function withdraw() public onlyOwner {
        uint256 balance = address(this).balance;

        address acct = 0x88110386fC2e19C7aECb9Ed242E65d5eEd165EE0;
        address studio = 0x388CcBf8c1A37F444DcFF6eDE0014DfA85BeDC1B;

        uint256 acct_share = balance / 100 * 85;
        uint256 studio_share = balance / 100 * 15;

        payable(acct).transfer(acct_share);
        payable(studio).transfer(studio_share);
    }

    function burn(uint256 tokenId) public virtual {
        require(_isApprovedOrOwner(_msgSender(), tokenId), "ERC721Burnable: caller is not owner nor approved");
        _burn(tokenId);
    }
}

{
  "compilationTarget": {
    "IBISChessclub.sol": "IBISChessclub"
  },
  "evmVersion": "london",
  "libraries": {},
  "metadata": {
    "bytecodeHash": "ipfs"
  },
  "optimizer": {
    "enabled": true,
    "runs": 200
  },
  "remappings": []
}