Dutch auction example

DutchAuction.sol

/**
 *Submitted for verification at Etherscan.io on 2021-10-31
*/

// File: https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/utils/Strings.sol


// OpenZeppelin Contracts v4.3.2 (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: https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/utils/Context.sol


// OpenZeppelin Contracts v4.3.2 (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: https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/access/Ownable.sol


// OpenZeppelin Contracts v4.3.2 (access/Ownable.sol)

pragma solidity ^0.8.0;


/**
 * @dev Contract module which provides a basic access control mechanism, where
 * there is an account (an owner) that can be granted exclusive access to
 * specific functions.
 *
 * By default, the owner account will be the one that deploys the contract. This
 * can later be changed with {transferOwnership}.
 *
 * This module is used through inheritance. It will make available the modifier
 * `onlyOwner`, which can be applied to your functions to restrict their use to
 * the owner.
 */
abstract contract Ownable is Context {
    address private _owner;

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    constructor() {
        _transferOwnership(_msgSender());
    }

    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view virtual returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        require(owner() == _msgSender(), "Ownable: caller is not the owner");
        _;
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions anymore. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby removing any functionality that is only available to the owner.
     */
    function renounceOwnership() public virtual onlyOwner {
        _transferOwnership(address(0));
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public virtual onlyOwner {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        _transferOwnership(newOwner);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Internal function without access restriction.
     */
    function _transferOwnership(address newOwner) internal virtual {
        address oldOwner = _owner;
        _owner = newOwner;
        emit OwnershipTransferred(oldOwner, newOwner);
    }
}

// File: https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/utils/Address.sol


// OpenZeppelin Contracts v4.3.2 (utils/Address.sol)

pragma solidity ^0.8.0;

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

// File: https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/token/ERC721/IERC721Receiver.sol


// OpenZeppelin Contracts v4.3.2 (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: https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/utils/introspection/IERC165.sol


// OpenZeppelin Contracts v4.3.2 (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: https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/utils/introspection/ERC165.sol


// OpenZeppelin Contracts v4.3.2 (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: https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/token/ERC721/IERC721.sol


// OpenZeppelin Contracts v4.3.2 (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: https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/token/ERC721/extensions/IERC721Enumerable.sol


// OpenZeppelin Contracts v4.3.2 (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: https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/token/ERC721/extensions/IERC721Metadata.sol


// OpenZeppelin Contracts v4.3.2 (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: https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/token/ERC721/ERC721.sol


// OpenZeppelin Contracts v4.3.2 (token/ERC721/ERC721.sol)

pragma solidity ^0.8.0;








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

    // Token name
    string private _name;

    // Token symbol
    string private _symbol;

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

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

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

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

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

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

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

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

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

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

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

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

    /**
     * @dev Base URI for computing {tokenURI}. If set, the resulting URI for each
     * token will be the concatenation of the `baseURI` and the `tokenId`. Empty
     * by default, can be overriden in child contracts.
     */
    function _baseURI() internal view virtual returns (string memory) {
        return "";
    }

    /**
     * @dev See {IERC721-approve}.
     */
    function approve(address to, uint256 tokenId) public virtual override {
        address owner = ERC721.ownerOf(tokenId);
        require(to != owner, "ERC721: approval to current owner");

        require(
            _msgSender() == owner || isApprovedForAll(owner, _msgSender()),
            "ERC721: approve caller is not owner nor approved for all"
        );

        _approve(to, tokenId);
    }

    /**
     * @dev See {IERC721-getApproved}.
     */
    function getApproved(uint256 tokenId) public view virtual override returns (address) {
        require(_exists(tokenId), "ERC721: approved query for nonexistent token");

        return _tokenApprovals[tokenId];
    }

    /**
     * @dev See {IERC721-setApprovalForAll}.
     */
    function setApprovalForAll(address operator, bool approved) public virtual override {
        _setApprovalForAll(_msgSender(), operator, approved);
    }

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

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

        _transfer(from, to, tokenId);
    }

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

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

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

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

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

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

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

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

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

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

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

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

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

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

// File: https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/token/ERC721/extensions/ERC721Enumerable.sol


// OpenZeppelin Contracts v4.3.2 (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();
    }
}

// File: mintPass.sol

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



// SafeMath for Safe calculation of UINT256
library SafeMath {
    function mul(uint256 a, uint256 b) internal pure returns (uint256 c) {
        if (a == 0) { return 0; }
        c = a * b;
        require(c / a == b);
        return c;
    }
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        return a / b;
    }
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b <= a);
        return a - b;
    }
    function add(uint256 a, uint256 b) internal pure returns (uint256 c) {
        c = a + b;
        require(c >= a);
        return c;
    }
}

contract nonFungibleFungiMintPass is ERC721Enumerable, Ownable {
    /* Created by: 0xInuarashi
    Discord: 0xInuarashi#1234
    Twitter: https://twitter.com/0xinuarashi */ 

    constructor() payable ERC721("NonFungibleFungiMintPass", "NFFMINT") {}

    // Initialize SafeMath library for UINT
    using SafeMath for uint;

    // General NFT Variables
    uint public maxTokens = 10000;

    uint public tokensReservedForWhitelist = 6695;
    uint public tokensMintedForWhitelist = 0;

    uint public tokensReservedForDutchAuction = 3000;
    uint public tokensMintedForDutchAuction = 0;

    uint public tokensReservedForReserved = 305;
    uint public tokensMintedForReserved = 0;

    string internal baseTokenURI;
    string internal baseTokenURI_EXT;

    event MintAsOwner(address indexed to, uint tokenId);
    event MintWhitelist(address indexed to, uint tokenId);
    event MintDutchAuction(address indexed to, uint price, uint tokenId);
    event MintRolloverSale(address indexed to, uint tokenId);

    // Modifiers
    modifier onlySender {
        require (msg.sender == tx.origin, "No smart contracts!");
        _;
    }
    
    // Contract Governance
    mapping(address => bool) internal shareholderToUnlockGovernance;

    address internal Shareholder_1 = 0x9eEFBb6759E48aAafd8a49d825abFdD0B22d5aD1;
    address internal Shareholder_2 = 0x506aeaEb48cA2E4145910606a6Fe97f294477d1B;
    address internal Shareholder_3 = 0x2f3Db2A40C01d1fDd6Fd4ac6040684292B8807e8;
    address internal Shareholder_4 = 0x458E0c06506eabE9C21074A46E7fAb70672D6205;
    address internal Shareholder_5 = 0x2cF855E17bD28Bb34982Ca1E4371ef7d3E6817e1;
    address internal Shareholder_6 = 0xB4C84F2848ba2FF988f4Ca33A5b37f0FCC4a60c2;
    address internal Shareholder_7 = 0x1eD3D146cb5945e1C894A70013Ed83F95693EA22; 

    uint internal Shareholder_1_Share = 7; 
    uint internal Shareholder_2_Share = 7;
    uint internal Shareholder_3_Share = 21; 
    uint internal Shareholder_4_Share = 35;
    uint internal Shareholder_5_Share = 12;
    uint internal Shareholder_6_Share = 10; 
    uint internal Shareholder_7_Share = 8; 

    // Receive Ether
    event Received(address from, uint amount);
    receive() external payable {
        emit Received(msg.sender, msg.value);
    }

    // Withdraw Ether 
    function withdrawEther() public onlyOwner {
        uint _totalETH = address(this).balance;
        
        uint _Shareholder_1_ETH = ((_totalETH * Shareholder_1_Share) / 100);
        uint _Shareholder_2_ETH = ((_totalETH * Shareholder_2_Share) / 100);
        uint _Shareholder_3_ETH = ((_totalETH * Shareholder_3_Share) / 100);
        uint _Shareholder_4_ETH = ((_totalETH * Shareholder_4_Share) / 100);
        uint _Shareholder_5_ETH = ((_totalETH * Shareholder_5_Share) / 100);
        uint _Shareholder_6_ETH = ((_totalETH * Shareholder_6_Share) / 100);
        uint _Shareholder_7_ETH = ((_totalETH * Shareholder_7_Share) / 100);
        
        payable(Shareholder_1).transfer(_Shareholder_1_ETH);
        payable(Shareholder_2).transfer(_Shareholder_2_ETH);
        payable(Shareholder_3).transfer(_Shareholder_3_ETH);
        payable(Shareholder_4).transfer(_Shareholder_4_ETH);
        payable(Shareholder_5).transfer(_Shareholder_5_ETH);
        payable(Shareholder_6).transfer(_Shareholder_6_ETH);
        payable(Shareholder_7).transfer(_Shareholder_7_ETH);
    }

    function viewWithdrawEtherAmounts() public view onlyOwner returns (uint[] memory) {
        uint _totalETH = address(this).balance;
        uint[] memory _ethToSendArray = new uint[](9);
        
        uint _Shareholder_1_ETH = ((_totalETH * Shareholder_1_Share) / 100);
        uint _Shareholder_2_ETH = ((_totalETH * Shareholder_2_Share) / 100);
        uint _Shareholder_3_ETH = ((_totalETH * Shareholder_3_Share) / 100);
        uint _Shareholder_4_ETH = ((_totalETH * Shareholder_4_Share) / 100);
        uint _Shareholder_5_ETH = ((_totalETH * Shareholder_5_Share) / 100);
        uint _Shareholder_6_ETH = ((_totalETH * Shareholder_6_Share) / 100);
        uint _Shareholder_7_ETH = ((_totalETH * Shareholder_7_Share) / 100);

        _ethToSendArray[0] = _Shareholder_1_ETH;
        _ethToSendArray[1] = _Shareholder_2_ETH;
        _ethToSendArray[2] = _Shareholder_3_ETH;
        _ethToSendArray[3] = _Shareholder_4_ETH;
        _ethToSendArray[4] = _Shareholder_5_ETH;
        _ethToSendArray[5] = _Shareholder_6_ETH;
        _ethToSendArray[6] = _Shareholder_7_ETH;
        _ethToSendArray[7] = _totalETH; // Total ETH
        _ethToSendArray[8] = _Shareholder_1_ETH + _Shareholder_2_ETH + _Shareholder_3_ETH + _Shareholder_4_ETH + _Shareholder_5_ETH + _Shareholder_6_ETH + _Shareholder_7_ETH; // Total ETH added from shareholders

        return _ethToSendArray;
    }

    // Emergency Withdraw -- Tested and working!
    // Governance Functions
    // It looks super hardcoded but I guess it's okay for something like this.
    modifier onlyShareholder {
        require(msg.sender == Shareholder_1 || msg.sender == Shareholder_2 || msg.sender == Shareholder_3 || msg.sender == Shareholder_4 || msg.sender == Shareholder_5 || msg.sender == Shareholder_6 || msg.sender == Shareholder_7, "You are not a shareholder!");
        _;
    }
    function unlockEmergencyFunctionAsShareholder() public onlyShareholder {
        shareholderToUnlockGovernance[msg.sender] = true;
    }

    modifier emergencyOnly {
        require(shareholderToUnlockGovernance[Shareholder_1] && shareholderToUnlockGovernance[Shareholder_2] && shareholderToUnlockGovernance[Shareholder_3] && shareholderToUnlockGovernance[Shareholder_4] && shareholderToUnlockGovernance[Shareholder_5] && shareholderToUnlockGovernance[Shareholder_6] && shareholderToUnlockGovernance[Shareholder_7], "The emergency function has not been unlocked!");
        _;
    }
    function emergencyWithdrawEther() public onlyOwner emergencyOnly {
        payable(msg.sender).transfer(address(this).balance); 
    }
    // Check Governance View function
    function checkGovernanceStatus(address address_) public view onlyShareholder returns (bool) {
        return shareholderToUnlockGovernance[address_];
    }

    ////////// Minting /////////////

    // Owner Mint
    function ownerMintMany(address address_, uint amount_) public onlyOwner {
        require(tokensReservedForReserved >= tokensMintedForReserved + amount_, "No more reserved tokens!");

        tokensMintedForReserved += amount_; // increment tokens minted for reserved

        for (uint i = 0; i < amount_; i++) {
            uint _mintId = totalSupply();
            _mint(address_, _mintId);

            emit MintAsOwner(address_, _mintId);
        }
    }
    function ownerMint(address address_) public onlyOwner {
        require(tokensReservedForReserved > tokensMintedForReserved, "No more reserved tokens!");

        tokensMintedForReserved++; // increment tokens minted for reserved

        uint _mintId = totalSupply();
        _mint(address_, _mintId);

        emit MintAsOwner(address_, _mintId);
    }
    
    // Whitelist Items
    uint public addressesWhitelisted = 0; // tracker for whitelist amount
    uint public whiteListPrice = 0.08 ether; // fixed price for whitelisted addresses
    mapping(address => uint) public addressToWhitelistQuota; // mapping for whitelist to quota
    mapping(address => uint) public addressToWhitelistMinted; // mapping for whitelist to minted
    bool public whiteListMintEnabled;

    modifier whiteListMint {
        require(whiteListMintEnabled, "Whitelist Mints are not enabled yet!");
        _;
    }

    // Whitelist Functions
    function setWhiteListMintStatus(bool bool_) public onlyOwner {
        whiteListMintEnabled = bool_;
    }
    function addAddressToWhitelist(address[] memory addresses_) public onlyOwner {
        uint _amountOfAddresses = addresses_.length;
        for (uint i = 0; i < _amountOfAddresses; i++) {
            addressToWhitelistQuota[addresses_[i]] = 1; // record the whitelisted address and quota
        }
        addressesWhitelisted += _amountOfAddresses; // increase tracker by amount of whitelisted addreses
    }
    function checkWhitelistArrayIsUnique(address[] memory addresses_) public view onlyOwner returns (bool) {
        uint _amountOfAddresses = addresses_.length;
        for (uint i = 0; i < _amountOfAddresses; i++) {
            if (addressToWhitelistQuota[addresses_[i]] == 1) {
                return false;
            }
        }
        return true;
    }
    function checkWhitelistArrayIsAllUnclaimed(address[] memory addresses_) public view onlyOwner returns (bool) {
        uint _amountOfAddresses = addresses_.length;
        for (uint i = 0; i < _amountOfAddresses; i++) {
            if (addressToWhitelistMinted[msg.sender] != 0) {
                return false;
            }
        }
        return true;
    }
    function mintWhitelist() public payable onlySender whiteListMint {
        require(addressToWhitelistQuota[msg.sender] > 0, "You are not whitelisted!");
        require(addressToWhitelistMinted[msg.sender] == 0, "You have no more whitelist mints left!");
        require(msg.value == whiteListPrice, "Invalid value sent!");
        require(tokensReservedForWhitelist > tokensMintedForWhitelist, "No more whitelist tokens!");
        require(maxTokens > totalSupply(), "No more tokens remaining!");

        addressToWhitelistMinted[msg.sender]++; // increments the tracker so that they cannot mint again
        tokensMintedForWhitelist++; // increments tracker of how many tokens have been minted from whitelist

        uint _mintId = totalSupply();
        _mint(msg.sender, _mintId);

        emit MintWhitelist(msg.sender, _mintId);
    }

    // Merkle Tree Whitelisting
    bytes32 public merkleRoot = 0x57c359b719e25852692060d2b4d8ce73ad9fea9406622eab2d3cb352cf46373c;

    function setMerkleRoot(bytes32 merkleRoot_) public onlyOwner {
        merkleRoot = merkleRoot_;
    }

    function isMerkleWhitelisted(bytes32[] memory proof_) public view returns (bool) {
        bytes32 _leaf = keccak256(abi.encodePacked(msg.sender));
        
        for (uint i = 0; i < proof_.length; i++) {
            _leaf = _leaf < proof_[i] ? keccak256(abi.encodePacked(_leaf, proof_[i])) : keccak256(abi.encodePacked(proof_[i], _leaf));
        }
        return _leaf == merkleRoot;
    }

    function mintWhitelistMerkleTree(bytes32[] memory proof_) public payable onlySender whiteListMint {
        require(isMerkleWhitelisted(proof_), "You are not whitelisted!");
        require(addressToWhitelistMinted[msg.sender] == 0, "You have no more whitelist mints left!");
        require(msg.value == whiteListPrice, "Invalid value sent!");
        require(tokensReservedForWhitelist > tokensMintedForWhitelist, "No more whitelist tokens!");
        require(maxTokens > totalSupply(), "No more tokens remaining!");

        addressToWhitelistMinted[msg.sender]++; // increments the tracker so that they cannot mint again
        tokensMintedForWhitelist++; // increments tracker of how many tokens have been minted from whitelist

        uint _mintId = totalSupply();
        _mint(msg.sender, _mintId);

        emit MintWhitelist(msg.sender, _mintId);
    }
    
    // Dutch Auction Items
    uint public dutchEndingPrice = 0.08 ether;
    uint public dutchPriceAdditional; // = 2.02 ether, record the additional price of dutch and deduct
    uint public dutchStartTime; // record the start time
    uint public dutchDuration; // record the duration
    uint public dutchEndTime; // record the end time
    bool public dutchAuctionStarted; // boolean for dutch auction

    modifier dutchAuction {
        require(dutchAuctionStarted && block.timestamp >= dutchStartTime, "Dutch auction has not started yet!");
        _;
    }
    function setDutchAuctionStartStatus(bool bool_) public onlyOwner {
        dutchAuctionStarted = bool_;
    }

    // Dutch Action Initialize
    function setDutchAuction(uint dutchPriceAdditional_, uint dutchStartTime_, uint dutchDuration_) public onlyOwner {
        dutchPriceAdditional = dutchPriceAdditional_; // set the additional price of dutch to deduct
        dutchStartTime = dutchStartTime_; // record the current start time as UNIX timestamp
        dutchDuration = dutchDuration_; // record the duration of the dutch in order to deduct
        dutchEndTime = dutchStartTime.add(dutchDuration); // record for safekeeping the ending time
    }

    // Dutch Auction Functions
    function getTimeElapsed() public view returns (uint) {
        return dutchStartTime > 0 ? dutchStartTime.add(dutchDuration) >= block.timestamp ? block.timestamp.sub(dutchStartTime) : dutchDuration : 0; // this value will end at dutchDuration as maximum.
    }
    function getTimeRemaining() public view returns (uint) {
        return dutchDuration.sub(getTimeElapsed());
    }

    function getAdditionalPrice() public view returns (uint) {
        return dutchDuration.sub(getTimeElapsed()).mul(dutchPriceAdditional).div(dutchDuration); // magic equation to calculate additional price on top of ending price
    }
    function getCurrentDutchPrice() public view returns (uint) {
        return dutchEndingPrice.add(getAdditionalPrice());
    }

    // untested
    function mintDutchAuctionMany(uint amount_) public payable onlySender dutchAuction {
        require(tokensReservedForDutchAuction >= tokensMintedForDutchAuction + amount_, "No more tokens for Dutch Auction!");
        require(maxTokens >= totalSupply() + amount_, "No more tokens remaining!");
        require(5 >= amount_, "You can only mint up to 5 per transaction!");
        require(msg.value >= getCurrentDutchPrice() * amount_, "Invalid value sent!");

        tokensMintedForDutchAuction += amount_; // increase tokens minted for dutch auction tracker

        for (uint i = 0; i < amount_; i++) {

            uint _mintId = totalSupply();
            uint _currentPrice = getCurrentDutchPrice();
            _mint(msg.sender, _mintId);
            
            emit MintDutchAuction(msg.sender, _currentPrice, _mintId);
        }
    }

    function mintDutchAuction() public payable onlySender dutchAuction {
        require(tokensReservedForDutchAuction > tokensMintedForDutchAuction, "No more tokens for Dutch Auction!");
        require(maxTokens > totalSupply(), "No more tokens remaining!");
        require(msg.value >= getCurrentDutchPrice(), "Invalid value sent!");

        tokensMintedForDutchAuction++; // increase tokens minted for dutch auction tracker

        uint _mintId = totalSupply();
        uint _currentPrice = getCurrentDutchPrice();
        _mint(msg.sender, _mintId);
        
        emit MintDutchAuction(msg.sender, _currentPrice, _mintId);
    }

    // Rollover Sale Items
    uint public rolloverSalePrice;
    uint public rolloverSaleStartTime; 
    bool public rolloverSaleStarted;
    uint public rolloverSaleTokensMinted;

    modifier rolloverSale {
        require(rolloverSaleStarted && block.timestamp >= rolloverSaleStartTime, "Rollover sale has not started yet!");
        _;
    }
    // Rollover Sale Functions
    function setRolloverSalePrice(uint price_) public onlyOwner {
        rolloverSalePrice = price_;
    }
    function setRolloverSaleStatus(uint rolloverSaleStartTime_, bool bool_) public onlyOwner {
        require(rolloverSalePrice != 0, "You have not set a rollover sale price!");
        rolloverSaleStartTime = rolloverSaleStartTime_;
        rolloverSaleStarted = bool_;
    }
    function mintRolloverSaleMany(uint amount_) public payable onlySender rolloverSale {
        require(maxTokens >= totalSupply() + amount_, "No remaining tokens left!");
        require(5 >= amount_, "You can only mint up to 5 per transaction!");
        require(msg.value == rolloverSalePrice * amount_, "Invalid value sent!");

        rolloverSaleTokensMinted += amount_; // add to tracker of public sale tokens minted

        for (uint i = 0; i < amount_; i++) {
            uint _mintId = totalSupply();
            _mint(msg.sender, _mintId);

            emit MintRolloverSale(msg.sender, _mintId);
        }
    }
    function mintRolloverSale() public payable onlySender rolloverSale {
        require(maxTokens > totalSupply(), "No remaining tokens left!");
        require(msg.value == rolloverSalePrice, "Invalid value sent!");

        rolloverSaleTokensMinted++; // add to tracker of public sale tokens minted

        uint _mintId = totalSupply();
        _mint(msg.sender, _mintId);

        emit MintRolloverSale(msg.sender, _mintId);
    }

    // General NFT Administration
    function setBaseTokenURI(string memory uri_) external onlyOwner {
        baseTokenURI = uri_;
    }
    function setBaseTokenURI_EXT(string memory ext_) external onlyOwner {
        baseTokenURI_EXT = ext_;
    }

    function tokenURI(uint tokenId_) public view override returns (string memory) {
        require(_exists(tokenId_), "Query for non-existent token!");
        return string(abi.encodePacked(baseTokenURI, Strings.toString(tokenId_), baseTokenURI_EXT));
    }
    function walletOfOwner(address address_) public view returns (uint[] memory) {
        uint _balance = balanceOf(address_); // get balance of address
        uint[] memory _tokenIds = new uint[](_balance); // initialize array 
        for (uint i = 0; i < _balance; i++) {
            _tokenIds[i] = tokenOfOwnerByIndex(address_, i);
        }
        return _tokenIds;
    }
}