// SPDX-License-Identifier: MIT
    // File: @openzeppelin/contracts/utils/Counters.sol

    pragma solidity ^0.8.0;

    /**
    * @title Counters
    * @author Matt Condon (@shrugs)
    * @dev Provides counters that can only be incremented, decremented or reset. This can be used e.g. to track the number
    * of elements in a mapping, issuing ERC721 ids, or counting request ids.
    *
    * Include with `using Counters for Counters.Counter;`
    */
    library Counters {
        struct Counter {
            // This variable should never be directly accessed by users of the library: interactions must be restricted to
            // the library's function. As of Solidity v0.5.2, this cannot be enforced, though there is a proposal to add
            // this feature: see https://github.com/ethereum/solidity/issues/4637
            uint256 _value; // default: 0
        }

        function current(Counter storage counter) internal view returns (uint256) {
            return counter._value;
        }

        function increment(Counter storage counter) internal {
            unchecked {
                counter._value += 1;
            }
        }

        function decrement(Counter storage counter) internal {
            uint256 value = counter._value;
            require(value > 0, "Counter: decrement overflow");
            unchecked {
                counter._value = value - 1;
            }
        }

        function reset(Counter storage counter) internal {
            counter._value = 0;
        }
    }

    // File: @openzeppelin/contracts/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/utils/introspection/IERC165.sol

    pragma solidity ^0.8.0;

    /**
    * @dev Interface of the ERC165 standard, as defined in the
    * https://eips.ethereum.org/EIPS/eip-165[EIP].
    *
    * Implementers can declare support of contract interfaces, which can then be
    * queried by others ({ERC165Checker}).
    *
    * For an implementation, see {ERC165}.
    */
    interface IERC165 {
        /**
        * @dev Returns true if this contract implements the interface defined by
        * `interfaceId`. See the corresponding
        * https://eips.ethereum.org/EIPS/eip-165#how-interfaces-are-identified[EIP section]
        * to learn more about how these ids are created.
        *
        * This function call must use less than 30 000 gas.
        */
        function supportsInterface(bytes4 interfaceId) external view returns (bool);
    }

    // File: @openzeppelin/contracts/token/ERC721/IERC721.sol

    pragma solidity ^0.8.0;

    /**
    * @dev Required interface of an ERC721 compliant contract.
    */
    interface IERC721 is IERC165 {
        /**
        * @dev Emitted when `tokenId` token is transferred from `from` to `to`.
        */
        event Transfer(
            address indexed from,
            address indexed to,
            uint256 indexed tokenId
        );

        /**
        * @dev Emitted when `owner` enables `approved` to manage the `tokenId` token.
        */
        event Approval(
            address indexed owner,
            address indexed approved,
            uint256 indexed tokenId
        );

        /**
        * @dev Emitted when `owner` enables or disables (`approved`) `operator` to manage all of its assets.
        */
        event ApprovalForAll(
            address indexed owner,
            address indexed operator,
            bool approved
        );

        /**
        * @dev Returns the number of tokens in ``owner``'s account.
        */
        function balanceOf(address owner) external view returns (uint256 balance);

        /**
        * @dev Returns the owner of the `tokenId` token.
        *
        * Requirements:
        *
        * - `tokenId` must exist.
        */
        function ownerOf(uint256 tokenId) external view returns (address owner);

        /**
        * @dev Safely transfers `tokenId` token from `from` to `to`, checking first that contract recipients
        * are aware of the ERC721 protocol to prevent tokens from being forever locked.
        *
        * Requirements:
        *
        * - `from` cannot be the zero address.
        * - `to` cannot be the zero address.
        * - `tokenId` token must exist and be owned by `from`.
        * - If the caller is not `from`, it must be have been allowed to move this token by either {approve} or {setApprovalForAll}.
        * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
        *
        * Emits a {Transfer} event.
        */
        function safeTransferFrom(
            address from,
            address to,
            uint256 tokenId
        ) external;

        /**
        * @dev Transfers `tokenId` token from `from` to `to`.
        *
        * WARNING: Usage of this method is discouraged, use {safeTransferFrom} whenever possible.
        *
        * Requirements:
        *
        * - `from` cannot be the zero address.
        * - `to` cannot be the zero address.
        * - `tokenId` token must be owned by `from`.
        * - If the caller is not `from`, it must be approved to move this token by either {approve} or {setApprovalForAll}.
        *
        * Emits a {Transfer} event.
        */
        function transferFrom(
            address from,
            address to,
            uint256 tokenId
        ) external;

        /**
        * @dev Gives permission to `to` to transfer `tokenId` token to another account.
        * The approval is cleared when the token is transferred.
        *
        * Only a single account can be approved at a time, so approving the zero address clears previous approvals.
        *
        * Requirements:
        *
        * - The caller must own the token or be an approved operator.
        * - `tokenId` must exist.
        *
        * Emits an {Approval} event.
        */
        function approve(address to, uint256 tokenId) external;

        /**
        * @dev Returns the account approved for `tokenId` token.
        *
        * Requirements:
        *
        * - `tokenId` must exist.
        */
        function getApproved(uint256 tokenId)
            external
            view
            returns (address operator);

        /**
        * @dev Approve or remove `operator` as an operator for the caller.
        * Operators can call {transferFrom} or {safeTransferFrom} for any token owned by the caller.
        *
        * Requirements:
        *
        * - The `operator` cannot be the caller.
        *
        * Emits an {ApprovalForAll} event.
        */
        function setApprovalForAll(address operator, bool _approved) external;

        /**
        * @dev Returns if the `operator` is allowed to manage all of the assets of `owner`.
        *
        * See {setApprovalForAll}
        */
        function isApprovedForAll(address owner, address operator)
            external
            view
            returns (bool);

        /**
        * @dev Safely transfers `tokenId` token from `from` to `to`.
        *
        * Requirements:
        *
        * - `from` cannot be the zero address.
        * - `to` cannot be the zero address.
        * - `tokenId` token must exist and be owned by `from`.
        * - If the caller is not `from`, it must be approved to move this token by either {approve} or {setApprovalForAll}.
        * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
        *
        * Emits a {Transfer} event.
        */
        function safeTransferFrom(
            address from,
            address to,
            uint256 tokenId,
            bytes calldata data
        ) external;
    }

    // File: @openzeppelin/contracts/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() {
            _setOwner(_msgSender());
        }

        /**
        * @dev Returns the address of the current owner.
        */
        function owner() public view virtual returns (address) {
            return _owner;
        }

        /**
        * @dev Throws if called by any account other than the owner.
        */
        modifier onlyOwner() {
            require(owner() == _msgSender(), "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 {
            _setOwner(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"
            );
            _setOwner(newOwner);
        }

        function _setOwner(address newOwner) private {
            address oldOwner = _owner;
            _owner = newOwner;
            emit OwnershipTransferred(oldOwner, newOwner);
        }
    }

    // File: @openzeppelin/contracts/token/ERC721/extensions/IERC721Enumerable.sol

    pragma solidity ^0.8.0;

    /**
    * @title ERC-721 Non-Fungible Token Standard, optional enumeration extension
    * @dev See https://eips.ethereum.org/EIPS/eip-721
    */
    interface IERC721Enumerable is IERC721 {
        /**
        * @dev Returns the total amount of tokens stored by the contract.
        */
        function totalSupply() external view returns (uint256);

        /**
        * @dev Returns a token ID owned by `owner` at a given `index` of its token list.
        * Use along with {balanceOf} to enumerate all of ``owner``'s tokens.
        */
        function tokenOfOwnerByIndex(address owner, uint256 index)
            external
            view
            returns (uint256 tokenId);

        /**
        * @dev Returns a token ID at a given `index` of all the tokens stored by the contract.
        * Use along with {totalSupply} to enumerate all tokens.
        */
        function tokenByIndex(uint256 index) external view returns (uint256);
    }

    // File: @openzeppelin/contracts/utils/introspection/ERC165.sol

    pragma solidity ^0.8.0;

    /**
    * @dev Implementation of the {IERC165} interface.
    *
    * Contracts that want to implement ERC165 should inherit from this contract and override {supportsInterface} to check
    * for the additional interface id that will be supported. For example:
    *
    * ```solidity
    * function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
    *     return interfaceId == type(MyInterface).interfaceId || super.supportsInterface(interfaceId);
    * }
    * ```
    *
    * Alternatively, {ERC165Storage} provides an easier to use but more expensive implementation.
    */
    abstract contract ERC165 is IERC165 {
        /**
        * @dev See {IERC165-supportsInterface}.
        */
        function supportsInterface(bytes4 interfaceId)
            public
            view
            virtual
            override
            returns (bool)
        {
            return interfaceId == type(IERC165).interfaceId;
        }
    }

    // File: @openzeppelin/contracts/utils/Strings.sol

    pragma solidity ^0.8.0;

    /**
    * @dev String operations.
    */
    library Strings {
        bytes16 private constant _HEX_SYMBOLS = "0123456789abcdef";

        /**
        * @dev Converts a `uint256` to its ASCII `string` decimal representation.
        */
        function toString(uint256 value) internal pure returns (string memory) {
            // Inspired by OraclizeAPI's implementation - MIT licence
            // https://github.com/oraclize/ethereum-api/blob/b42146b063c7d6ee1358846c198246239e9360e8/oraclizeAPI_0.4.25.sol

            if (value == 0) {
                return "0";
            }
            uint256 temp = value;
            uint256 digits;
            while (temp != 0) {
                digits++;
                temp /= 10;
            }
            bytes memory buffer = new bytes(digits);
            while (value != 0) {
                digits -= 1;
                buffer[digits] = bytes1(uint8(48 + uint256(value % 10)));
                value /= 10;
            }
            return string(buffer);
        }

        /**
        * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation.
        */
        function toHexString(uint256 value) internal pure returns (string memory) {
            if (value == 0) {
                return "0x00";
            }
            uint256 temp = value;
            uint256 length = 0;
            while (temp != 0) {
                length++;
                temp >>= 8;
            }
            return toHexString(value, length);
        }

        /**
        * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation with fixed length.
        */
        function toHexString(uint256 value, uint256 length)
            internal
            pure
            returns (string memory)
        {
            bytes memory buffer = new bytes(2 * length + 2);
            buffer[0] = "0";
            buffer[1] = "x";
            for (uint256 i = 2 * length + 1; i > 1; --i) {
                buffer[i] = _HEX_SYMBOLS[value & 0xf];
                value >>= 4;
            }
            require(value == 0, "Strings: hex length insufficient");
            return string(buffer);
        }
    }

    // File: @openzeppelin/contracts/utils/Address.sol

    pragma solidity ^0.8.0;

    /**
    * @dev Collection of functions related to the address type
    */
    library Address {
        /**
        * @dev Returns true if `account` is a contract.
        *
        * [IMPORTANT]
        * ====
        * It is unsafe to assume that an address for which this function returns
        * false is an externally-owned account (EOA) and not a contract.
        *
        * Among others, `isContract` will return false for the following
        * types of addresses:
        *
        *  - an externally-owned account
        *  - a contract in construction
        *  - an address where a contract will be created
        *  - an address where a contract lived, but was destroyed
        * ====
        */
        function isContract(address account) internal view returns (bool) {
            // This method relies on extcodesize, which returns 0 for contracts in
            // construction, since the code is only stored at the end of the
            // constructor execution.

            uint256 size;
            assembly {
                size := extcodesize(account)
            }
            return size > 0;
        }

        /**
        * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
        * `recipient`, forwarding all available gas and reverting on errors.
        *
        * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
        * of certain opcodes, possibly making contracts go over the 2300 gas limit
        * imposed by `transfer`, making them unable to receive funds via
        * `transfer`. {sendValue} removes this limitation.
        *
        * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
        *
        * IMPORTANT: because control is transferred to `recipient`, care must be
        * taken to not create reentrancy vulnerabilities. Consider using
        * {ReentrancyGuard} or the
        * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
        */
        function sendValue(address payable recipient, uint256 amount) internal {
            require(
                address(this).balance >= amount,
                "Address: insufficient balance"
            );

            (bool success, ) = recipient.call{value: amount}("");
            require(
                success,
                "Address: unable to send value, recipient may have reverted"
            );
        }

        /**
        * @dev Performs a Solidity function call using a low level `call`. A
        * plain `call` is an unsafe replacement for a function call: use this
        * function instead.
        *
        * If `target` reverts with a revert reason, it is bubbled up by this
        * function (like regular Solidity function calls).
        *
        * Returns the raw returned data. To convert to the expected return value,
        * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
        *
        * Requirements:
        *
        * - `target` must be a contract.
        * - calling `target` with `data` must not revert.
        *
        * _Available since v3.1._
        */
        function functionCall(address target, bytes memory data)
            internal
            returns (bytes memory)
        {
            return functionCall(target, data, "Address: low-level call failed");
        }

        /**
        * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
        * `errorMessage` as a fallback revert reason when `target` reverts.
        *
        * _Available since v3.1._
        */
        function functionCall(
            address target,
            bytes memory data,
            string memory errorMessage
        ) internal returns (bytes memory) {
            return functionCallWithValue(target, data, 0, errorMessage);
        }

        /**
        * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
        * but also transferring `value` wei to `target`.
        *
        * Requirements:
        *
        * - the calling contract must have an ETH balance of at least `value`.
        * - the called Solidity function must be `payable`.
        *
        * _Available since v3.1._
        */
        function functionCallWithValue(
            address target,
            bytes memory data,
            uint256 value
        ) internal returns (bytes memory) {
            return
                functionCallWithValue(
                    target,
                    data,
                    value,
                    "Address: low-level call with value failed"
                );
        }

        /**
        * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
        * with `errorMessage` as a fallback revert reason when `target` reverts.
        *
        * _Available since v3.1._
        */
        function functionCallWithValue(
            address target,
            bytes memory data,
            uint256 value,
            string memory errorMessage
        ) internal returns (bytes memory) {
            require(
                address(this).balance >= value,
                "Address: insufficient balance for call"
            );
            require(isContract(target), "Address: call to non-contract");

            (bool success, bytes memory returndata) = target.call{value: value}(
                data
            );
            return _verifyCallResult(success, returndata, errorMessage);
        }

        /**
        * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
        * but performing a static call.
        *
        * _Available since v3.3._
        */
        function functionStaticCall(address target, bytes memory data)
            internal
            view
            returns (bytes memory)
        {
            return
                functionStaticCall(
                    target,
                    data,
                    "Address: low-level static call failed"
                );
        }

        /**
        * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
        * but performing a static call.
        *
        * _Available since v3.3._
        */
        function functionStaticCall(
            address target,
            bytes memory data,
            string memory errorMessage
        ) internal view returns (bytes memory) {
            require(isContract(target), "Address: static call to non-contract");

            (bool success, bytes memory returndata) = target.staticcall(data);
            return _verifyCallResult(success, returndata, errorMessage);
        }

        /**
        * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
        * but performing a delegate call.
        *
        * _Available since v3.4._
        */
        function functionDelegateCall(address target, bytes memory data)
            internal
            returns (bytes memory)
        {
            return
                functionDelegateCall(
                    target,
                    data,
                    "Address: low-level delegate call failed"
                );
        }

        /**
        * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
        * but performing a delegate call.
        *
        * _Available since v3.4._
        */
        function functionDelegateCall(
            address target,
            bytes memory data,
            string memory errorMessage
        ) internal returns (bytes memory) {
            require(isContract(target), "Address: delegate call to non-contract");

            (bool success, bytes memory returndata) = target.delegatecall(data);
            return _verifyCallResult(success, returndata, errorMessage);
        }

        function _verifyCallResult(
            bool success,
            bytes memory returndata,
            string memory errorMessage
        ) private pure returns (bytes memory) {
            if (success) {
                return returndata;
            } else {
                // Look for revert reason and bubble it up if present
                if (returndata.length > 0) {
                    // The easiest way to bubble the revert reason is using memory via assembly

                    assembly {
                        let returndata_size := mload(returndata)
                        revert(add(32, returndata), returndata_size)
                    }
                } else {
                    revert(errorMessage);
                }
            }
        }
    }

    // File: @openzeppelin/contracts/token/ERC721/extensions/IERC721Metadata.sol

    pragma solidity ^0.8.0;

    /**
    * @title ERC-721 Non-Fungible Token Standard, optional metadata extension
    * @dev See https://eips.ethereum.org/EIPS/eip-721
    */
    interface IERC721Metadata is IERC721 {
        /**
        * @dev Returns the token collection name.
        */
        function name() external view returns (string memory);

        /**
        * @dev Returns the token collection symbol.
        */
        function symbol() external view returns (string memory);

        /**
        * @dev Returns the Uniform Resource Identifier (URI) for `tokenId` token.
        */
        function tokenURI(uint256 tokenId) external view returns (string memory);
    }

    // File: @openzeppelin/contracts/token/ERC721/IERC721Receiver.sol

    pragma solidity ^0.8.0;

    /**
    * @title ERC721 token receiver interface
    * @dev Interface for any contract that wants to support safeTransfers
    * from ERC721 asset contracts.
    */
    interface IERC721Receiver {
        /**
        * @dev Whenever an {IERC721} `tokenId` token is transferred to this contract via {IERC721-safeTransferFrom}
        * by `operator` from `from`, this function is called.
        *
        * It must return its Solidity selector to confirm the token transfer.
        * If any other value is returned or the interface is not implemented by the recipient, the transfer will be reverted.
        *
        * The selector can be obtained in Solidity with `IERC721.onERC721Received.selector`.
        */
        function onERC721Received(
            address operator,
            address from,
            uint256 tokenId,
            bytes calldata data
        ) external returns (bytes4);
    }

    // File: @openzeppelin/contracts/token/ERC721/ERC721.sol

    pragma solidity ^0.8.0;

    /**
    * @dev Implementation of https://eips.ethereum.org/EIPS/eip-721[ERC721] Non-Fungible Token Standard, including
    * the Metadata extension, but not including the Enumerable extension, which is available separately as
    * {ERC721Enumerable}.
    */
    contract ERC721 is Context, ERC165, IERC721, IERC721Metadata {
        using Address for address;
        using Strings for uint256;

        // Token name
        string private _name;

        // Token symbol
        string private _symbol;

        // Mapping from token ID to owner address
        mapping(uint256 => address) private _owners;

        // Mapping owner address to token count
        mapping(address => uint256) private _balances;

        // Mapping from token ID to approved address
        mapping(uint256 => address) private _tokenApprovals;

        // Mapping from owner to operator approvals
        mapping(address => mapping(address => bool)) private _operatorApprovals;

        /**
        * @dev Initializes the contract by setting a `name` and a `symbol` to the token collection.
        */
        constructor(string memory name_, string memory symbol_) {
            _name = name_;
            _symbol = symbol_;
        }

        /**
        * @dev See {IERC165-supportsInterface}.
        */
        function supportsInterface(bytes4 interfaceId)
            public
            view
            virtual
            override(ERC165, IERC165)
            returns (bool)
        {
            return
                interfaceId == type(IERC721).interfaceId ||
                interfaceId == type(IERC721Metadata).interfaceId ||
                super.supportsInterface(interfaceId);
        }

        /**
        * @dev See {IERC721-balanceOf}.
        */
        function balanceOf(address owner)
            public
            view
            virtual
            override
            returns (uint256)
        {
            require(
                owner != address(0),
                "ERC721: balance query for the zero address"
            );
            return _balances[owner];
        }

        /**
        * @dev See {IERC721-ownerOf}.
        */
        function ownerOf(uint256 tokenId)
            public
            view
            virtual
            override
            returns (address)
        {
            address owner = _owners[tokenId];
            require(
                owner != address(0),
                "ERC721: owner query for nonexistent token"
            );
            return owner;
        }

        /**
        * @dev See {IERC721Metadata-name}.
        */
        function name() public view virtual override returns (string memory) {
            return _name;
        }

        /**
        * @dev See {IERC721Metadata-symbol}.
        */
        function symbol() public view virtual override returns (string memory) {
            return _symbol;
        }

        /**
        * @dev See {IERC721Metadata-tokenURI}.
        */
        function tokenURI(uint256 tokenId)
            public
            view
            virtual
            override
            returns (string memory)
        {
            require(
                _exists(tokenId),
                "ERC721Metadata: URI query for nonexistent token"
            );

            string memory baseURI = _baseURI();
            return
                bytes(baseURI).length > 0
                    ? string(abi.encodePacked(baseURI, tokenId.toString()))
                    : "";
        }

        /**
        * @dev Base URI for computing {tokenURI}. If set, the resulting URI for each
        * token will be the concatenation of the `baseURI` and the `tokenId`. Empty
        * by default, can be overriden in child contracts.
        */
        function _baseURI() internal view virtual returns (string memory) {
            return "";
        }

        /**
        * @dev See {IERC721-approve}.
        */
        function approve(address to, uint256 tokenId) public virtual override {
            address owner = ERC721.ownerOf(tokenId);
            require(to != owner, "ERC721: approval to current owner");

            require(
                _msgSender() == owner || isApprovedForAll(owner, _msgSender()),
                "ERC721: approve caller is not owner nor approved for all"
            );

            _approve(to, tokenId);
        }

        /**
        * @dev See {IERC721-getApproved}.
        */
        function getApproved(uint256 tokenId)
            public
            view
            virtual
            override
            returns (address)
        {
            require(
                _exists(tokenId),
                "ERC721: approved query for nonexistent token"
            );

            return _tokenApprovals[tokenId];
        }

        /**
        * @dev See {IERC721-setApprovalForAll}.
        */
        function setApprovalForAll(address operator, bool approved)
            public
            virtual
            override
        {
            require(operator != _msgSender(), "ERC721: approve to caller");

            _operatorApprovals[_msgSender()][operator] = approved;
            emit ApprovalForAll(_msgSender(), operator, approved);
        }

        /**
        * @dev See {IERC721-isApprovedForAll}.
        */
        function isApprovedForAll(address owner, address operator)
            public
            view
            virtual
            override
            returns (bool)
        {
            return _operatorApprovals[owner][operator];
        }

        /**
        * @dev See {IERC721-transferFrom}.
        */
        function transferFrom(
            address from,
            address to,
            uint256 tokenId
        ) public virtual override {
            //solhint-disable-next-line max-line-length
            require(
                _isApprovedOrOwner(_msgSender(), tokenId),
                "ERC721: transfer caller is not owner nor approved"
            );

            _transfer(from, to, tokenId);
        }

        /**
        * @dev See {IERC721-safeTransferFrom}.
        */
        function safeTransferFrom(
            address from,
            address to,
            uint256 tokenId
        ) public virtual override {
            safeTransferFrom(from, to, tokenId, "");
        }

        /**
        * @dev See {IERC721-safeTransferFrom}.
        */
        function safeTransferFrom(
            address from,
            address to,
            uint256 tokenId,
            bytes memory _data
        ) public virtual override {
            require(
                _isApprovedOrOwner(_msgSender(), tokenId),
                "ERC721: transfer caller is not owner nor approved"
            );
            _safeTransfer(from, to, tokenId, _data);
        }

        /**
        * @dev Safely transfers `tokenId` token from `from` to `to`, checking first that contract recipients
        * are aware of the ERC721 protocol to prevent tokens from being forever locked.
        *
        * `_data` is additional data, it has no specified format and it is sent in call to `to`.
        *
        * This internal function is equivalent to {safeTransferFrom}, and can be used to e.g.
        * implement alternative mechanisms to perform token transfer, such as signature-based.
        *
        * Requirements:
        *
        * - `from` cannot be the zero address.
        * - `to` cannot be the zero address.
        * - `tokenId` token must exist and be owned by `from`.
        * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
        *
        * Emits a {Transfer} event.
        */
        function _safeTransfer(
            address from,
            address to,
            uint256 tokenId,
            bytes memory _data
        ) internal virtual {
            _transfer(from, to, tokenId);
            require(
                _checkOnERC721Received(from, to, tokenId, _data),
                "ERC721: transfer to non ERC721Receiver implementer"
            );
        }

        /**
        * @dev Returns whether `tokenId` exists.
        *
        * Tokens can be managed by their owner or approved accounts via {approve} or {setApprovalForAll}.
        *
        * Tokens start existing when they are minted (`_mint`),
        * and stop existing when they are burned (`_burn`).
        */
        function _exists(uint256 tokenId) internal view virtual returns (bool) {
            return _owners[tokenId] != address(0);
        }

        /**
        * @dev Returns whether `spender` is allowed to manage `tokenId`.
        *
        * Requirements:
        *
        * - `tokenId` must exist.
        */
        function _isApprovedOrOwner(address spender, uint256 tokenId)
            internal
            view
            virtual
            returns (bool)
        {
            require(
                _exists(tokenId),
                "ERC721: operator query for nonexistent token"
            );
            address owner = ERC721.ownerOf(tokenId);
            return (spender == owner ||
                getApproved(tokenId) == spender ||
                isApprovedForAll(owner, spender));
        }

        /**
        * @dev Safely mints `tokenId` and transfers it to `to`.
        *
        * Requirements:
        *
        * - `tokenId` must not exist.
        * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
        *
        * Emits a {Transfer} event.
        */
        function _safeMint(address to, uint256 tokenId) internal virtual {
            _safeMint(to, tokenId, "");
        }

        /**
        * @dev Same as {xref-ERC721-_safeMint-address-uint256-}[`_safeMint`], with an additional `data` parameter which is
        * forwarded in {IERC721Receiver-onERC721Received} to contract recipients.
        */
        function _safeMint(
            address to,
            uint256 tokenId,
            bytes memory _data
        ) internal virtual {
            _mint(to, tokenId);
            require(
                _checkOnERC721Received(address(0), to, tokenId, _data),
                "ERC721: transfer to non ERC721Receiver implementer"
            );
        }

        /**
        * @dev Mints `tokenId` and transfers it to `to`.
        *
        * WARNING: Usage of this method is discouraged, use {_safeMint} whenever possible
        *
        * Requirements:
        *
        * - `tokenId` must not exist.
        * - `to` cannot be the zero address.
        *
        * Emits a {Transfer} event.
        */
        function _mint(address to, uint256 tokenId) internal virtual {
            require(to != address(0), "ERC721: mint to the zero address");
            require(!_exists(tokenId), "ERC721: token already minted");

            _beforeTokenTransfer(address(0), to, tokenId);

            _balances[to] += 1;
            _owners[tokenId] = to;

            emit Transfer(address(0), to, tokenId);
        }

        /**
        * @dev Destroys `tokenId`.
        * The approval is cleared when the token is burned.
        *
        * Requirements:
        *
        * - `tokenId` must exist.
        *
        * Emits a {Transfer} event.
        */
        function _burn(uint256 tokenId) internal virtual {
            address owner = ERC721.ownerOf(tokenId);

            _beforeTokenTransfer(owner, address(0), tokenId);

            // Clear approvals
            _approve(address(0), tokenId);

            _balances[owner] -= 1;
            delete _owners[tokenId];

            emit Transfer(owner, address(0), tokenId);
        }

        /**
        * @dev Transfers `tokenId` from `from` to `to`.
        *  As opposed to {transferFrom}, this imposes no restrictions on msg.sender.
        *
        * Requirements:
        *
        * - `to` cannot be the zero address.
        * - `tokenId` token must be owned by `from`.
        *
        * Emits a {Transfer} event.
        */
        function _transfer(
            address from,
            address to,
            uint256 tokenId
        ) internal virtual {
            require(
                ERC721.ownerOf(tokenId) == from,
                "ERC721: transfer of token that is not own"
            );
            require(to != address(0), "ERC721: transfer to the zero address");

            _beforeTokenTransfer(from, to, tokenId);

            // Clear approvals from the previous owner
            _approve(address(0), tokenId);

            _balances[from] -= 1;
            _balances[to] += 1;
            _owners[tokenId] = to;

            emit Transfer(from, to, tokenId);
        }

        /**
        * @dev Approve `to` to operate on `tokenId`
        *
        * Emits a {Approval} event.
        */
        function _approve(address to, uint256 tokenId) internal virtual {
            _tokenApprovals[tokenId] = to;
            emit Approval(ERC721.ownerOf(tokenId), to, tokenId);
        }

        /**
        * @dev Internal function to invoke {IERC721Receiver-onERC721Received} on a target address.
        * The call is not executed if the target address is not a contract.
        *
        * @param from address representing the previous owner of the given token ID
        * @param to target address that will receive the tokens
        * @param tokenId uint256 ID of the token to be transferred
        * @param _data bytes optional data to send along with the call
        * @return bool whether the call correctly returned the expected magic value
        */
        function _checkOnERC721Received(
            address from,
            address to,
            uint256 tokenId,
            bytes memory _data
        ) private returns (bool) {
            if (to.isContract()) {
                try
                    IERC721Receiver(to).onERC721Received(
                        _msgSender(),
                        from,
                        tokenId,
                        _data
                    )
                returns (bytes4 retval) {
                    return retval == IERC721Receiver(to).onERC721Received.selector;
                } catch (bytes memory reason) {
                    if (reason.length == 0) {
                        revert(
                            "ERC721: transfer to non ERC721Receiver implementer"
                        );
                    } else {
                        assembly {
                            revert(add(32, reason), mload(reason))
                        }
                    }
                }
            } else {
                return true;
            }
        }

        /**
        * @dev Hook that is called before any token transfer. This includes minting
        * and burning.
        *
        * Calling conditions:
        *
        * - When `from` and `to` are both non-zero, ``from``'s `tokenId` will be
        * transferred to `to`.
        * - When `from` is zero, `tokenId` will be minted for `to`.
        * - When `to` is zero, ``from``'s `tokenId` will be burned.
        * - `from` and `to` are never both zero.
        *
        * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
        */
        function _beforeTokenTransfer(
            address from,
            address to,
            uint256 tokenId
        ) internal virtual {}
    }

    // File: @openzeppelin/contracts/token/ERC721/extensions/ERC721Enumerable.sol

    pragma solidity ^0.8.0;

    /**
    * @dev This implements an optional extension of {ERC721} defined in the EIP that adds
    * enumerability of all the token ids in the contract as well as all token ids owned by each
    * account.
    */
    abstract contract ERC721Enumerable is ERC721, IERC721Enumerable {
        // Mapping from owner to list of owned token IDs
        mapping(address => mapping(uint256 => uint256)) private _ownedTokens;

        // Mapping from token ID to index of the owner tokens list
        mapping(uint256 => uint256) private _ownedTokensIndex;

        // Array with all token ids, used for enumeration
        uint256[] private _allTokens;

        // Mapping from token id to position in the allTokens array
        mapping(uint256 => uint256) private _allTokensIndex;

        /**
        * @dev See {IERC165-supportsInterface}.
        */
        function supportsInterface(bytes4 interfaceId)
            public
            view
            virtual
            override(IERC165, ERC721)
            returns (bool)
        {
            return
                interfaceId == type(IERC721Enumerable).interfaceId ||
                super.supportsInterface(interfaceId);
        }

        /**
        * @dev See {IERC721Enumerable-tokenOfOwnerByIndex}.
        */
        function tokenOfOwnerByIndex(address owner, uint256 index)
            public
            view
            virtual
            override
            returns (uint256)
        {
            require(
                index < ERC721.balanceOf(owner),
                "ERC721Enumerable: owner index out of bounds"
            );
            return _ownedTokens[owner][index];
        }

        /**
        * @dev See {IERC721Enumerable-totalSupply}.
        */
        function totalSupply() public view virtual override returns (uint256) {
            return _allTokens.length;
        }

        /**
        * @dev See {IERC721Enumerable-tokenByIndex}.
        */
        function tokenByIndex(uint256 index)
            public
            view
            virtual
            override
            returns (uint256)
        {
            require(
                index < ERC721Enumerable.totalSupply(),
                "ERC721Enumerable: global index out of bounds"
            );
            return _allTokens[index];
        }

        /**
        * @dev Hook that is called before any token transfer. This includes minting
        * and burning.
        *
        * Calling conditions:
        *
        * - When `from` and `to` are both non-zero, ``from``'s `tokenId` will be
        * transferred to `to`.
        * - When `from` is zero, `tokenId` will be minted for `to`.
        * - When `to` is zero, ``from``'s `tokenId` will be burned.
        * - `from` cannot be the zero address.
        * - `to` cannot be the zero address.
        *
        * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
        */
        function _beforeTokenTransfer(
            address from,
            address to,
            uint256 tokenId
        ) internal virtual override {
            super._beforeTokenTransfer(from, to, tokenId);

            if (from == address(0)) {
                _addTokenToAllTokensEnumeration(tokenId);
            } else if (from != to) {
                _removeTokenFromOwnerEnumeration(from, tokenId);
            }
            if (to == address(0)) {
                _removeTokenFromAllTokensEnumeration(tokenId);
            } else if (to != from) {
                _addTokenToOwnerEnumeration(to, tokenId);
            }
        }

        /**
        * @dev Private function to add a token to this extension's ownership-tracking data structures.
        * @param to address representing the new owner of the given token ID
        * @param tokenId uint256 ID of the token to be added to the tokens list of the given address
        */
        function _addTokenToOwnerEnumeration(address to, uint256 tokenId) private {
            uint256 length = ERC721.balanceOf(to);
            _ownedTokens[to][length] = tokenId;
            _ownedTokensIndex[tokenId] = length;
        }

        /**
        * @dev Private function to add a token to this extension's token tracking data structures.
        * @param tokenId uint256 ID of the token to be added to the tokens list
        */
        function _addTokenToAllTokensEnumeration(uint256 tokenId) private {
            _allTokensIndex[tokenId] = _allTokens.length;
            _allTokens.push(tokenId);
        }

        /**
        * @dev Private function to remove a token from this extension's ownership-tracking data structures. Note that
        * while the token is not assigned a new owner, the `_ownedTokensIndex` mapping is _not_ updated: this allows for
        * gas optimizations e.g. when performing a transfer operation (avoiding double writes).
        * This has O(1) time complexity, but alters the order of the _ownedTokens array.
        * @param from address representing the previous owner of the given token ID
        * @param tokenId uint256 ID of the token to be removed from the tokens list of the given address
        */
        function _removeTokenFromOwnerEnumeration(address from, uint256 tokenId)
            private
        {
            // To prevent a gap in from's tokens array, we store the last token in the index of the token to delete, and
            // then delete the last slot (swap and pop).

            uint256 lastTokenIndex = ERC721.balanceOf(from) - 1;
            uint256 tokenIndex = _ownedTokensIndex[tokenId];

            // When the token to delete is the last token, the swap operation is unnecessary
            if (tokenIndex != lastTokenIndex) {
                uint256 lastTokenId = _ownedTokens[from][lastTokenIndex];

                _ownedTokens[from][tokenIndex] = lastTokenId; // Move the last token to the slot of the to-delete token
                _ownedTokensIndex[lastTokenId] = tokenIndex; // Update the moved token's index
            }

            // This also deletes the contents at the last position of the array
            delete _ownedTokensIndex[tokenId];
            delete _ownedTokens[from][lastTokenIndex];
        }

        /**
        * @dev Private function to remove a token from this extension's token tracking data structures.
        * This has O(1) time complexity, but alters the order of the _allTokens array.
        * @param tokenId uint256 ID of the token to be removed from the tokens list
        */
        function _removeTokenFromAllTokensEnumeration(uint256 tokenId) private {
            // To prevent a gap in the tokens array, we store the last token in the index of the token to delete, and
            // then delete the last slot (swap and pop).

            uint256 lastTokenIndex = _allTokens.length - 1;
            uint256 tokenIndex = _allTokensIndex[tokenId];

            // When the token to delete is the last token, the swap operation is unnecessary. However, since this occurs so
            // rarely (when the last minted token is burnt) that we still do the swap here to avoid the gas cost of adding
            // an 'if' statement (like in _removeTokenFromOwnerEnumeration)
            uint256 lastTokenId = _allTokens[lastTokenIndex];

            _allTokens[tokenIndex] = lastTokenId; // Move the last token to the slot of the to-delete token
            _allTokensIndex[lastTokenId] = tokenIndex; // Update the moved token's index

            // This also deletes the contents at the last position of the array
            delete _allTokensIndex[tokenId];
            _allTokens.pop();
        }
    }

    pragma solidity ^0.8.0;

    contract ShibElonNFT is ERC721Enumerable, Ownable {
        using Counters for Counters.Counter;
        Counters.Counter private _tokenId;

        uint256 public MAX_SUPPLY = 3000;
        uint256 public lastSupply;
        uint256 public MAX_ALLOWED = 10;
        uint256 public price = 0.04 ether;
        uint256 public BUYBACK_PERCENTAGE = 10;
        string baseTokenURI;
        
        bool public saleOpen = false;
        
        uint256[3000] public remainingIds;
        mapping(uint256 => address) public minters;

        uint256[] public mintedIDs;

        event NFTMinted(uint256 totalMinted);

        constructor(string memory baseURI) ERC721("ShibElon NFT", "SHIBELON") {
            setBaseURI(baseURI);
            lastSupply = MAX_SUPPLY;
        }

        //Get token Ids of all tokens owned by _owner
        function getTokenIds(address _owner)
            external
            view
            returns (uint256[] memory)
        {
            uint256 tokenCount = balanceOf(_owner);

            uint256[] memory tokensId = new uint256[](tokenCount);
            for (uint256 i = 0; i < tokenCount; i++) {
                tokensId[i] = tokenOfOwnerByIndex(_owner, i);
            }

            return tokensId;
        }

        function _randomMint(address _walletAddress) internal returns (uint256) {
            uint256 _index = _getRandom() % lastSupply;
            uint256 _realIndex = getValue(_index) + 1;
            mintedIDs.push(_realIndex);
            lastSupply--;
            remainingIds[_index] = getValue(lastSupply);
            
            _safeMint(_walletAddress, _realIndex);
            minters[_realIndex] = _walletAddress;

            return _realIndex;
        }

        function randomAirdrop(address _walletAddress, uint256 _mintCount) external onlyOwner {
            require(_walletAddress != address(0), "Cannot airdrop to null address");
            require(_mintCount > 0, "Invalid mint count");
            require(lastSupply != 0,  "The collection is sold out");
            // Mint random NFTs for airdrop
            for (uint256 i = 1; i <= _mintCount; i++) {
                _randomMint(_walletAddress);
            }
        }

        function randomAirdropBulk(address[] calldata _walletAddresses) external onlyOwner {
            for (uint256 i = 0; i < _walletAddresses.length; i++) {
                require(lastSupply != 0,  "The collection is sold out");
                // Mint random NFTs for airdrop
                _randomMint(_walletAddresses[i]);  
            }
        }

        function getMintedIds() public view returns (uint256[] memory){
            return mintedIDs;
        }

        // Get value from a remaining id node
        function getValue(uint _index) internal view returns(uint256){
            if(remainingIds[_index] != 0) return remainingIds[_index];
            else return _index;
        }

        // Create a random id for minting
        function _getRandom() internal view returns (uint256) {
            return
            uint256(
                keccak256(
                abi.encodePacked(block.prevrandao, block.timestamp, lastSupply)
                )
            );
        }

        function setBaseURI(string memory baseURI) public onlyOwner {
            baseTokenURI = baseURI;
        }

        function setPrice(uint256 _newPrice) public onlyOwner {
            price = _newPrice;
        }

        function setMaxAllowd(uint256 _maxAllowed) public onlyOwner {
            MAX_ALLOWED = _maxAllowed;
        }
        
        function setMaxSupply(uint256 _max_supply) public onlyOwner {
            MAX_SUPPLY = _max_supply;
        }

        function getPrice() external view returns(uint256){
            return price;
        }
        
        //Close sale
        function pauseSale() public onlyOwner {
            saleOpen = false;
        }
        
        //Open sale
        function unpauseSale() public onlyOwner {
            saleOpen = true;
        }

        function withdrawAll() public onlyOwner {
            (bool success, ) = msg.sender.call{value: address(this).balance}("");
            require(success, "Transfer failed.");
        }
        
        //mint NFT
        function mintNFT(uint256 _count) public payable{
            if (msg.sender != owner()) {
                require((saleOpen == true), "Sale is not open please try again later");
            }
            
            require(
                _count <= MAX_ALLOWED,
            "You have reached the NFT minting limit per transaction"
            );
            
        
            require(
                totalSupply() + _count < (MAX_SUPPLY),
                "All NFTs sold"
            );
         
            require(
                msg.value >= price * _count,
                "Ether sent with this transaction is not correct"
            );
            
            address _to = msg.sender;

            for (uint256 i = 0; i < _count; i++) {
                _randomMint(_to);
            }
        }
        
        function _baseURI() internal view virtual override returns (string memory) {
            return baseTokenURI;
        }
    }