// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @dev Collection of functions related to the address type
 */
library Address {
    /**
     * @dev Returns true if `account` is a contract.
     *
     * [IMPORTANT]
     * ====
     * It is unsafe to assume that an address for which this function returns
     * false is an externally-owned account (EOA) and not a contract.
     *
     * Among others, `isContract` will return false for the following
     * types of addresses:
     *
     *  - an externally-owned account
     *  - a contract in construction
     *  - an address where a contract will be created
     *  - an address where a contract lived, but was destroyed
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize, which returns 0 for contracts in
        // construction, since the code is only stored at the end of the
        // constructor execution.

        uint256 size;
        assembly {
            size := extcodesize(account)
        }
        return size > 0;
    }

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

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

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

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "./IERC165.sol";

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

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

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

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

    // Token name
    string private _name;

    // Token symbol
    string private _symbol;

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

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

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

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

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

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

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

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

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

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

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

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

    /**
     * @dev Base URI for computing {tokenURI}. 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 {}
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

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

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

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

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

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

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

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

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

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

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

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

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

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

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

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

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "../IERC721.sol";

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

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

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

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

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

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @dev Contract module that helps prevent reentrant calls to a function.
 *
 * Inheriting from `ReentrancyGuard` will make the {nonReentrant} modifier
 * available, which can be applied to functions to make sure there are no nested
 * (reentrant) calls to them.
 *
 * Note that because there is a single `nonReentrant` guard, functions marked as
 * `nonReentrant` may not call one another. This can be worked around by making
 * those functions `private`, and then adding `external` `nonReentrant` entry
 * points to them.
 *
 * TIP: If you would like to learn more about reentrancy and alternative ways
 * to protect against it, check out our blog post
 * https://blog.openzeppelin.com/reentrancy-after-istanbul/[Reentrancy After Istanbul].
 */
abstract contract ReentrancyGuard {
    // Booleans are more expensive than uint256 or any type that takes up a full
    // word because each write operation emits an extra SLOAD to first read the
    // slot's contents, replace the bits taken up by the boolean, and then write
    // back. This is the compiler's defense against contract upgrades and
    // pointer aliasing, and it cannot be disabled.

    // The values being non-zero value makes deployment a bit more expensive,
    // but in exchange the refund on every call to nonReentrant will be lower in
    // amount. Since refunds are capped to a percentage of the total
    // transaction's gas, it is best to keep them low in cases like this one, to
    // increase the likelihood of the full refund coming into effect.
    uint256 private constant _NOT_ENTERED = 1;
    uint256 private constant _ENTERED = 2;

    uint256 private _status;

    constructor() {
        _status = _NOT_ENTERED;
    }

    /**
     * @dev Prevents a contract from calling itself, directly or indirectly.
     * Calling a `nonReentrant` function from another `nonReentrant`
     * function is not supported. It is possible to prevent this from happening
     * by making the `nonReentrant` function external, and make it call a
     * `private` function that does the actual work.
     */
    modifier nonReentrant() {
        // On the first call to nonReentrant, _notEntered will be true
        require(_status != _ENTERED, "ReentrancyGuard: reentrant call");

        // Any calls to nonReentrant after this point will fail
        _status = _ENTERED;

        _;

        // By storing the original value once again, a refund is triggered (see
        // https://eips.ethereum.org/EIPS/eip-2200)
        _status = _NOT_ENTERED;
    }
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

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

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

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

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

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

// contracts/cryptoshack.sol
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.7;

import "./base_contracts/ERC721.sol";
import "@openzeppelin/contracts/security/ReentrancyGuard.sol";

interface IMulesquad {
    function ownerOf(uint256 tokenId) external view returns (address);
}

contract CryptoShack is ERC721, ReentrancyGuard {
    string _baseTokenURI;

    address public owner;

    IMulesquad internal mulesquadContract = IMulesquad(0xa088AC5a19c28c882D71725C268244b233CFFC62);

    uint constant public MAX_SUPPLY = 7200;
    uint constant public mintCost = 0.069 ether;
    uint constant public maxMintPerTx = 3;
    uint public maxPerWallet = 20;

    // external counter instead of ERC721Enumerable:totalSupply()
    uint256 public totalSupply;
    uint256 public publicMinted;

    uint256 public reserveMinted;
    uint256 public teamReserved = 300;

    uint256 public mulesquadClaimed;
    uint256 public mulesquadReserved = 690;

    // more random, rolled on noContracts
    bytes32 private entropySauce;
    uint private NOUNCE;

    // some numbers and trackers type-based
    uint[4][5] private typeToNumbers;
    bytes32[5] private typeToNames;

    // amount of tokens minted by wallet
    mapping(address => uint) private walletToMinted;
    // address to amount of tokens of every type owned
    mapping(address => uint[5]) private addressToTypesOwned;
    // address to last action block number
    mapping(address => uint) private callerToLastBlockAction;
    // map show if mulesquad ID was used to claim token or not
    mapping(uint => bool) private mulesquadIdToClaimed;

    bool public mintAllowed;
    bool public exchangeAllowed;
    bool public claimAllowed;
    bool public revealed;

    constructor() ERC721("CryptoShack", "SHACK") {
        owner=msg.sender;

        typeToNames[0]="gophers";
        typeToNames[1]="golden_gophers";
        typeToNames[2]="caddies";
        typeToNames[3]="legendaries";
        typeToNames[4]="members";

        // minted, burned, exchange scores, max amount
        typeToNumbers[0]=[0, 0, 1, 4700];     // GOPHER
        typeToNumbers[1]=[0, 0, 4, 150];      // GOLDEN_GOPHER
        typeToNumbers[2]=[0, 0, 2, 2350];     // CADDIE
        typeToNumbers[3]=[0, 0, 0, 18];       // LEGENDARIES
        typeToNumbers[4]=[0, 0, 0, 2500];     // MEMBER
    }

    //
    //  MINT
    //

    /// @dev mint tokens at public sale
    /// @param amount_ amount of tokens to mint
    function mintPublic(uint amount_) external payable onlyMintAllowed noContracts nonReentrant {
        require(msg.value == mintCost * amount_, "Invalid tx value!");                              //NOTE: check payment amount
        require(publicMinted + amount_ <= MAX_SUPPLY - teamReserved - mulesquadReserved, "No public mint available");                                                //NOTE: check if GOPHERS left to mint
        require(amount_ > 0 && amount_ <= maxMintPerTx, "Wrong mint amount");                      //NOTE: check if amount is correct
        require(walletToMinted[msg.sender] + amount_ <= maxPerWallet, "Wallet limit reached");      //NOTE: check max per wallet limit

        totalSupply+=amount_;
        publicMinted+=amount_;

        mintRandomInternal(amount_, msg.sender, false);
    }

    /// @dev mint tokens reserved for the team
    /// @param wallet wallet to mint tokens
    /// @param amount_ amount of tokens to mint
    function mintReserve(address wallet, uint amount_) external onlyOwner noContracts nonReentrant {
        require(reserveMinted + amount_ <= teamReserved);

        totalSupply+=amount_;
        reserveMinted+=amount_;

        mintRandomInternal(amount_,wallet, true);
    }

    /// @dev claim token with mulesquad token Id
    /// @param _mulesquadIds mulesquad token Id 
    function claimMulesquad(uint[] calldata _mulesquadIds) external onlyClaimAllowed noContracts nonReentrant {
        require(_mulesquadIds.length > 0, "Array can not be empty");
        require(mulesquadClaimed + _mulesquadIds.length <= mulesquadReserved); 
        require(walletToMinted[msg.sender] + _mulesquadIds.length <= maxPerWallet, "Wallet limit reached");

        totalSupply+=_mulesquadIds.length;
        mulesquadClaimed+=_mulesquadIds.length;

        for (uint i;i<_mulesquadIds.length;i++) {
            require(mulesquadContract.ownerOf(_mulesquadIds[i])==msg.sender, "You don't own the token");
            require(!mulesquadIdToClaimed[_mulesquadIds[i]], "Already used to claim");
            mulesquadIdToClaimed[_mulesquadIds[i]]=true;
        }

        mintRandomInternal(_mulesquadIds.length, msg.sender, false);
    }

    /// @dev exchange few tokens of type 0-2 to membership card (token types 3-4)
    /// @param _tokenIds array of tokens to be exchanged for membership
    function exchange(uint[] calldata _tokenIds) external onlyExchangeAllowed noContracts nonReentrant {
        require(_tokenIds.length>0, "Array can not be empty");
        uint scoresTotal;
        for (uint i;i<_tokenIds.length;i++) {
            require(_exists(_tokenIds[i]),"Token doesn't exists");
            require(msg.sender==ownerOf(_tokenIds[i]), "You are not the owner");
            uint scores = typeToNumbers[_tokenIds[i] / 10000][2];
            require(scores > 0, "Members can not be burned");
            scoresTotal+=scores;
        }

        require(scoresTotal == 4, "Scores total should be 4");

        totalSupply -= (_tokenIds.length-1);

        for (uint i;i<_tokenIds.length;i++) {
            burn(_tokenIds[i]);
        }

        // golden gopher burned, roll the special
        if (_tokenIds.length==1) {
            uint random = _getRandom(msg.sender, "exchange");
            // max golden gophers / golden gophers burned
            uint leftToMint = 150-typeToNumbers[1][1]+1;
            uint accumulated;

            for (uint j = 3; j<=4; j++) { 
                accumulated+=typeToNumbers[j][3]-typeToNumbers[j][0];
                if (random%leftToMint < accumulated) {
                    _mintInternal(msg.sender, j);
                    break;
                }
            }
        } else {
            _mintInternal(msg.sender, 4);
        }
    }

    /// @dev pick the random type (0-2) and mint it to specific address
    /// @param amount_ amount of tokens to be minted
    /// @param receiver wallet to get minted tokens
    function mintRandomInternal(uint amount_, address receiver, bool ignoreWalletRestriction) internal {
        if (!ignoreWalletRestriction) {
            walletToMinted[receiver]+=amount_;
        }

        uint leftToMint = MAX_SUPPLY - publicMinted - mulesquadClaimed - reserveMinted + amount_;
        uint accumulated;

        for (uint i = 0; i < amount_; i++) {
            uint random = _getRandom(msg.sender, "mint");

            accumulated = 0;
            // pick the type to mint
            for (uint j = 0; j<3; j++) { 
                accumulated+=typeToNumbers[j][3]-typeToNumbers[j][0];
                if (random%(leftToMint-i) < accumulated) {
                    _mintInternal(receiver, j);
                    break;
                }
            }
        }
    }

    /// @dev mint token of specific type to specified address
    /// @param receiver wallet to mint token to
    /// @param tokenType type of token to mint
    function _mintInternal(address receiver, uint tokenType) internal {
        uint mintId = ++typeToNumbers[tokenType][0] + tokenType*10000;
        _mint(receiver, mintId);
    }

    /// @dev burn the token specified
    /// @param _tokenId token Id to burn
    function burn(uint _tokenId) internal {
        uint tokenType=_tokenId / 10000;
        typeToNumbers[tokenType][1]++;
        _burn(_tokenId);
    }

    //
    //  VIEW
    //

    /// @dev return total amount of tokens of a type owned by wallet
    function ownedOfType(address address_, uint type_) external view noSameBlockAsAction returns(uint) {
        return addressToTypesOwned[address_][type_];
    }

    /// @dev return total amount of tokens minted
    function mintedTotal() external view returns (uint) {
        uint result;
        for (uint i=0;i<3;i++) {
            result+=typeToNumbers[i][0];
        }
        return result;
    }

    /// @dev return the array of tokens owned by wallet, never use from the contract (!)
    /// @param address_ wallet to check
    function walletOfOwner(address address_, uint type_) external view returns (uint[] memory) {
        require(callerToLastBlockAction[address_] < block.number, "Please try again on next block");
        uint[] memory _tokens = new uint[](addressToTypesOwned[address_][type_]);
        uint index;
        uint tokenId;
        uint type_minted=typeToNumbers[type_][0];
        for (uint j=1;j<=type_minted;j++) {
            tokenId=j+type_*10000;
            if (_exists(tokenId)) {
                if (ownerOf(tokenId)==address_) {_tokens[index++]=(tokenId);}
            }
        }
        return _tokens;
    }

    /// @dev return the metadata URI for specific token
    /// @param _tokenId token to get URI for
    function tokenURI(uint _tokenId) public view override noSameBlockAsAction returns (string memory) {
        require(_exists(_tokenId), "Token does not exist");
        if (!revealed) {
            return string(abi.encodePacked(_baseTokenURI, '/unrevealed/json/metadata.json'));
        }
        return string(abi.encodePacked(_baseTokenURI, '/', typeToNames[_tokenId/10000],'/','json/',Strings.toString(_tokenId%10000)));
    }

    /// @dev get the actual amount of tokens of specific type
    /// @param type_ token type (check typeToNumbers array)
    function getSupplyByType(uint type_) external view noSameBlockAsAction returns(uint) {
        return typeToNumbers[type_][0]-typeToNumbers[type_][1];
    }

    //
    // ONLY OWNER
    //

    /// @dev reveal the real links to metadata
    function reveal() external onlyOwner {
        revealed=true;
    }

    /// @dev free all Mulesquad reserved tokens for the public sale, can not be reverted
    function mulesquadClaimEnd() external onlyOwner {
        mulesquadReserved=mulesquadClaimed;
    }

    /// @dev switch mint allowed status
    function switchMintAllowed() external onlyOwner {
        mintAllowed=!mintAllowed;
    }

    /// @dev switch exchange allowed status
    function switchExchangeAllowed() external onlyOwner {
        exchangeAllowed=!exchangeAllowed;
    }

    /// @dev switch claim allowed status
    function switchClaimAllowed() external onlyOwner {
        claimAllowed=!claimAllowed;
    }

    /// @dev set wallet mint allowance
    /// @param maxPerWallet_ new wallet allowance, default is 20
    function setMaxPerWallet(uint maxPerWallet_) external onlyOwner {
        maxPerWallet=maxPerWallet_;
    }

    /// @dev Set base URI for tokenURI
    function setBaseTokenURI(string memory baseURI_) external onlyOwner {
        _baseTokenURI=baseURI_;
    }

    function setMulesquadContract(address mulesquadAddress_) external onlyOwner {
        mulesquadContract=IMulesquad(mulesquadAddress_);
    }

    /// @dev transfer ownership
    /// @param owner_ new contract owner
    function transferOwnership(address owner_) external onlyOwner {
        owner=owner_;
    }

    /// @dev withdraw all ETH accumulated, 10% share goes to solidity dev
    function withdrawEther() external onlyOwner {
        require(address(this).balance > 0);
        uint share = address(this).balance/10;
        payable(0xdA00D453F87db473BC84221063f4a27298F7FCca).transfer(share);
        payable(owner).transfer(address(this).balance);
    }

    //
    // HELPERS
    //

    /// @dev get pseudo random uint
    function _getRandom(address _address, bytes32 _addition) internal returns (uint){
        callerToLastBlockAction[tx.origin] = block.number;
        return uint256(
            keccak256(
                abi.encodePacked(
                    _address, 
                    block.timestamp, 
                    ++NOUNCE,
                    _addition,
                    block.basefee, 
                    block.timestamp, 
                    entropySauce)));
    }

    //
    //  MODIFIERS
    //

    /// @dev allow execution when mint allowed only
    modifier onlyMintAllowed() {
        require(mintAllowed, 'Mint not allowed');
        _;
    }

    /// @dev allow execution when claim only
    modifier onlyClaimAllowed() {
        require(claimAllowed, 'Claim not allowed');
        _;
    }

    /// @dev allow execution when exchange allowed only
    modifier onlyExchangeAllowed() {
        require(exchangeAllowed, "Exchange not allowed");
        _;
    }

    /// @dev allow execution when caller is owner only
    modifier onlyOwner() {
        require(owner == msg.sender, "You are not the owner");
        _;
    }

    /// @dev do not allow execution if caller is contract
    modifier noContracts() {
        uint256 size;
        address acc = msg.sender;
        assembly { size := extcodesize(acc)}

        require(msg.sender == tx.origin,  "tx.origin != msg.sender");
        require(size == 0,                "Contract calls are not allowed");
        _;

        // We'll use the last caller hash to add entropy to next caller
        entropySauce = keccak256(abi.encodePacked(acc, block.coinbase));
    }

    /// @dev don't allow view functions in same block as action that changed the state
    modifier noSameBlockAsAction() {
        require(callerToLastBlockAction[tx.origin] < block.number, "Please try again on next block");
        _;
    }

    //
    // OVERRIDE
    //

    /// @dev override to prohibit to get results in same block as random was rolled
    function balanceOf(address owner_) public view virtual override(ERC721) returns (uint256) {
        require(callerToLastBlockAction[owner_] < block.number, "Please try again on next block");
        return super.balanceOf(owner_);
    }

    /// @dev override to prohibit to get results in same block as random was rolled
    function ownerOf(uint256 tokenId) public view virtual override(ERC721) returns (address) {
        address addr = super.ownerOf(tokenId);
        require(callerToLastBlockAction[addr] < block.number, "Please try again on next block");
        return addr;
    }

    /// @dev override to track how many of a type wallet hold, required for custom walletOfOwner and ownedOfType
    function _beforeTokenTransfer(
        address from,
        address to,
        uint256 tokenId
    ) internal override virtual {
        uint tokenType = tokenId/10000;
        if (from!=address(0)) { addressToTypesOwned[from][tokenType]--; }
        if (to!=address(0)) { addressToTypesOwned[to][tokenType]++; }
    }
}

{
  "compilationTarget": {
    "contracts/cryptoshack.sol": "CryptoShack"
  },
  "evmVersion": "london",
  "libraries": {},
  "metadata": {
    "bytecodeHash": "ipfs"
  },
  "optimizer": {
    "enabled": false,
    "runs": 200
  },
  "remappings": []
}