// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;


// File: @openzeppelin/contracts/security/ReentrancyGuard.sol
// OpenZeppelin Contracts (last updated v4.8.0) (security/ReentrancyGuard.sol)

/**
 * @dev Contract module that helps prevent reentrant calls to a function.
 *
 * Inheriting from `ReentrancyGuard` will make the {nonReentrant} modifier
 * available, which can be applied to functions to make sure there are no nested
 * (reentrant) calls to them.
 *
 * Note that because there is a single `nonReentrant` guard, functions marked as
 * `nonReentrant` may not call one another. This can be worked around by making
 * those functions `private`, and then adding `external` `nonReentrant` entry
 * points to them.
 *
 * TIP: If you would like to learn more about reentrancy and alternative ways
 * to protect against it, check out our blog post
 * https://blog.openzeppelin.com/reentrancy-after-istanbul/[Reentrancy After Istanbul].
 */
abstract contract ReentrancyGuard {
    // Booleans are more expensive than uint256 or any type that takes up a full
    // word because each write operation emits an extra SLOAD to first read the
    // slot's contents, replace the bits taken up by the boolean, and then write
    // back. This is the compiler's defense against contract upgrades and
    // pointer aliasing, and it cannot be disabled.

    // The values being non-zero value makes deployment a bit more expensive,
    // but in exchange the refund on every call to nonReentrant will be lower in
    // amount. Since refunds are capped to a percentage of the total
    // transaction's gas, it is best to keep them low in cases like this one, to
    // increase the likelihood of the full refund coming into effect.
    uint256 private constant _NOT_ENTERED = 1;
    uint256 private constant _ENTERED = 2;

    uint256 private _status;

    constructor() {
        _status = _NOT_ENTERED;
    }

    /**
     * @dev Prevents a contract from calling itself, directly or indirectly.
     * Calling a `nonReentrant` function from another `nonReentrant`
     * function is not supported. It is possible to prevent this from happening
     * by making the `nonReentrant` function external, and making it call a
     * `private` function that does the actual work.
     */
    modifier nonReentrant() {
        _nonReentrantBefore();
        _;
        _nonReentrantAfter();
    }

    function _nonReentrantBefore() private {
        // On the first call to nonReentrant, _status will be _NOT_ENTERED
        require(_status != _ENTERED, "ReentrancyGuard: reentrant call");

        // Any calls to nonReentrant after this point will fail
        _status = _ENTERED;
    }

    function _nonReentrantAfter() private {
        // By storing the original value once again, a refund is triggered (see
        // https://eips.ethereum.org/EIPS/eip-2200)
        _status = _NOT_ENTERED;
    }
}


// File: @openzeppelin/contracts/token/ERC721/IERC721Receiver.sol
// OpenZeppelin Contracts (last updated v4.6.0) (token/ERC721/IERC721Receiver.sol)

/**
 * @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 `IERC721Receiver.onERC721Received.selector`.
     */
    function onERC721Received(
        address operator,
        address from,
        uint256 tokenId,
        bytes calldata data
    ) external returns (bytes4);
}


// File: @openzeppelin/contracts/token/ERC721/utils/ERC721Holder.sol
// OpenZeppelin Contracts v4.4.1 (token/ERC721/utils/ERC721Holder.sol)

/**
 * @dev Implementation of the {IERC721Receiver} interface.
 *
 * Accepts all token transfers.
 * Make sure the contract is able to use its token with {IERC721-safeTransferFrom}, {IERC721-approve} or {IERC721-setApprovalForAll}.
 */
contract ERC721Holder is IERC721Receiver {
    /**
     * @dev See {IERC721Receiver-onERC721Received}.
     *
     * Always returns `IERC721Receiver.onERC721Received.selector`.
     */
    function onERC721Received(
        address,
        address,
        uint256,
        bytes memory
    ) public virtual override returns (bytes4) {
        return this.onERC721Received.selector;
    }
}


// File: @openzeppelin/contracts/utils/Context.sol
// OpenZeppelin Contracts v4.4.1 (utils/Context.sol)

/**
 * @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/security/Pausable.sol
// OpenZeppelin Contracts (last updated v4.7.0) (security/Pausable.sol)

/**
 * @dev Contract module which allows children to implement an emergency stop
 * mechanism that can be triggered by an authorized account.
 *
 * This module is used through inheritance. It will make available the
 * modifiers `whenNotPaused` and `whenPaused`, which can be applied to
 * the functions of your contract. Note that they will not be pausable by
 * simply including this module, only once the modifiers are put in place.
 */
abstract contract Pausable is Context {
    /**
     * @dev Emitted when the pause is triggered by `account`.
     */
    event Paused(address account);

    /**
     * @dev Emitted when the pause is lifted by `account`.
     */
    event Unpaused(address account);

    bool private _paused;

    /**
     * @dev Initializes the contract in unpaused state.
     */
    constructor() {
        _paused = false;
    }

    /**
     * @dev Modifier to make a function callable only when the contract is not paused.
     *
     * Requirements:
     *
     * - The contract must not be paused.
     */
    modifier whenNotPaused() {
        _requireNotPaused();
        _;
    }

    /**
     * @dev Modifier to make a function callable only when the contract is paused.
     *
     * Requirements:
     *
     * - The contract must be paused.
     */
    modifier whenPaused() {
        _requirePaused();
        _;
    }

    /**
     * @dev Returns true if the contract is paused, and false otherwise.
     */
    function paused() public view virtual returns (bool) {
        return _paused;
    }

    /**
     * @dev Throws if the contract is paused.
     */
    function _requireNotPaused() internal view virtual {
        require(!paused(), "Pausable: paused");
    }

    /**
     * @dev Throws if the contract is not paused.
     */
    function _requirePaused() internal view virtual {
        require(paused(), "Pausable: not paused");
    }

    /**
     * @dev Triggers stopped state.
     *
     * Requirements:
     *
     * - The contract must not be paused.
     */
    function _pause() internal virtual whenNotPaused {
        _paused = true;
        emit Paused(_msgSender());
    }

    /**
     * @dev Returns to normal state.
     *
     * Requirements:
     *
     * - The contract must be paused.
     */
    function _unpause() internal virtual whenPaused {
        _paused = false;
        emit Unpaused(_msgSender());
    }
}


// File: @openzeppelin/contracts/access/Ownable.sol
// OpenZeppelin Contracts (last updated v4.7.0) (access/Ownable.sol)

/**
 * @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 Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        _checkOwner();
        _;
    }

    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view virtual returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if the sender is not the owner.
     */
    function _checkOwner() internal view virtual {
        require(owner() == _msgSender(), "Ownable: caller is not the owner");
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions anymore. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby removing any functionality that is only available to the owner.
     */
    function renounceOwnership() public virtual onlyOwner {
        _transferOwnership(address(0));
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public virtual onlyOwner {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        _transferOwnership(newOwner);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Internal function without access restriction.
     */
    function _transferOwnership(address newOwner) internal virtual {
        address oldOwner = _owner;
        _owner = newOwner;
        emit OwnershipTransferred(oldOwner, newOwner);
    }
}


// File: @openzeppelin/contracts/token/ERC20/IERC20.sol
// OpenZeppelin Contracts (last updated v4.6.0) (token/ERC20/IERC20.sol)

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}. `value` is the new allowance.
     */
    event Approval(address indexed owner, address indexed spender, uint256 value);

    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns the amount of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);

    /**
     * @dev Moves `amount` tokens from the caller's account to `to`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address to, uint256 amount) external returns (bool);

    /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}. This is
     * zero by default.
     *
     * This value changes when {approve} or {transferFrom} are called.
     */
    function allowance(address owner, address spender) external view returns (uint256);

    /**
     * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * IMPORTANT: Beware that changing an allowance with this method brings the risk
     * that someone may use both the old and the new allowance by unfortunate
     * transaction ordering. One possible solution to mitigate this race
     * condition is to first reduce the spender's allowance to 0 and set the
     * desired value afterwards:
     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
     *
     * Emits an {Approval} event.
     */
    function approve(address spender, uint256 amount) external returns (bool);

    /**
     * @dev Moves `amount` tokens from `from` to `to` using the
     * allowance mechanism. `amount` is then deducted from the caller's
     * allowance.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(
        address from,
        address to,
        uint256 amount
    ) external returns (bool);
}


// File: @openzeppelin/contracts/utils/introspection/IERC165.sol
// OpenZeppelin Contracts v4.4.1 (utils/introspection/IERC165.sol)

/**
 * @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
// OpenZeppelin Contracts (last updated v4.8.0) (token/ERC721/IERC721.sol)

/**
 * @dev Required interface of an ERC721 compliant contract.
 */
interface IERC721 is IERC165 {
    /**
     * @dev Emitted when `tokenId` token is transferred from `from` to `to`.
     */
    event Transfer(address indexed from, address indexed to, uint256 indexed tokenId);

    /**
     * @dev Emitted when `owner` enables `approved` to manage the `tokenId` token.
     */
    event Approval(address indexed owner, address indexed approved, uint256 indexed tokenId);

    /**
     * @dev Emitted when `owner` enables or disables (`approved`) `operator` to manage all of its assets.
     */
    event ApprovalForAll(address indexed owner, address indexed operator, bool approved);

    /**
     * @dev Returns the number of tokens in ``owner``'s account.
     */
    function balanceOf(address owner) external view returns (uint256 balance);

    /**
     * @dev Returns the owner of the `tokenId` token.
     *
     * Requirements:
     *
     * - `tokenId` must exist.
     */
    function ownerOf(uint256 tokenId) external view returns (address owner);

    /**
     * @dev Safely transfers `tokenId` token from `from` to `to`.
     *
     * 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;

    /**
     * @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 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: Note that the caller is responsible to confirm that the recipient is capable of receiving ERC721
     * or else they may be permanently lost. Usage of {safeTransferFrom} prevents loss, though the caller must
     * understand this adds an external call which potentially creates a reentrancy vulnerability.
     *
     * 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 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 the account approved for `tokenId` token.
     *
     * Requirements:
     *
     * - `tokenId` must exist.
     */
    function getApproved(uint256 tokenId) external view returns (address operator);

    /**
     * @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);
}


// File: StakingSPR.sol
// StakingSPR contract

contract StakingSPR is Ownable, ERC721Holder, ReentrancyGuard, Pausable {

    IERC721 public stakingToken; // Sheepoori SPR NFT
    IERC20 public rewardToken; // HAN token

    constructor(address _stakingToken, address _rewardToken) onlyOwner {
        stakingToken = IERC721(_stakingToken);
        rewardToken = IERC20(_rewardToken);
    }

    struct Staker {
        uint[] tokenIds;    // Stacked NFT tokenID
        uint totalReward;   // The total amount of HAN Token received as reward
        uint unclaimedRewards;  // The accumulated amount of HAN token before "CLAIM"
        uint amountStaked;  // The amount of NFT tokenID staked
        uint timeOfLastUpdate;  // Last updated time by NFT tokenID
    }

    uint public constant rewardTokenPerstakingToken = 1157407407407; // Quantity of HAN tokens rewarded per NFT tokenID	
    uint public totalSupply;    // Total amount of NFT tokenID staked
    uint public rewardsDuration = 31536000; // The total amount of HAN token available for reward = rewardTokenPerstakingToken * rewardsDuration
    
    mapping(uint => address) public tokenOwner; // Return owner address when NFT tokenID is entered
    mapping(address => Staker) public stakers;

    // ------------------ Admin ------------------ //

    // Pause Staking
    function pause() public onlyOwner {
        _pause();
    }
    function unpause() public onlyOwner {
        _unpause();
    }

    function setRewardsDuration(uint _newDuration) public onlyOwner {
        rewardsDuration = _newDuration;
    }

    // Lookup function for NFT tokenID deposited by mistake (not by staking)
    function unappliedStakingToken() public view returns (uint) {
        uint unappliedToken;
        uint balance = stakingToken.balanceOf(address(this));
        unappliedToken = balance - totalSupply;
        return unappliedToken;
    }

    function transferStakingToken(uint _tokenId) public onlyOwner {
        require(tokenOwner[_tokenId] == address(0), "The owner of NFT tokenID must not exist");
        stakingToken.safeTransferFrom(address(this), msg.sender, _tokenId);
    }

    function recoverERC20(address _tokenAddress, uint _tokenAmount) external onlyOwner {
        require(_tokenAddress != address(stakingToken), "Cannot withdraw the staking token");
        IERC20(_tokenAddress).transfer(msg.sender, _tokenAmount);
        emit RecoveredERC20(_tokenAddress, _tokenAmount);
    }

    function recoverERC721(address _tokenAddress, uint _tokenId) external onlyOwner {
        require(_tokenAddress != address(stakingToken), "Cannot withdraw the staking token");
        IERC721(_tokenAddress).safeTransferFrom(address(this), msg.sender, _tokenId);
        emit RecoveredERC721(_tokenAddress, _tokenId);
    }

    // ------------------ Transaction Functions ------------------ //

    // "STAKE" function
    function stake(uint _tokenId) public nonReentrant whenNotPaused {
        require(stakingToken.ownerOf(_tokenId) == msg.sender, "user must be the owner of the token");
        require(rewardToken.balanceOf(address(this)) > 0, "Reward Token 0");
        require(rewardToken.balanceOf(address(this)) - rewardsDuration * (totalSupply * rewardTokenPerstakingToken) > rewardsDuration * rewardTokenPerstakingToken,  "Total amount of rewards is too high");
        Staker storage staker = stakers[msg.sender];
        if(staker.amountStaked == 0) {
            staker.timeOfLastUpdate = block.timestamp;
            tokenOwner[_tokenId] = msg.sender;
            staker.amountStaked += 1;
            totalSupply += 1;
            staker.tokenIds.push(_tokenId);
            stakingToken.safeTransferFrom(msg.sender, address(this), _tokenId);
            emit Staked(msg.sender, _tokenId);
        }else {
            staker.unclaimedRewards += calculateRewards(msg.sender);
            staker.timeOfLastUpdate = block.timestamp;
            tokenOwner[_tokenId] = msg.sender;
            staker.amountStaked += 1;
            totalSupply += 1;
            staker.tokenIds.push(_tokenId);
            stakingToken.safeTransferFrom(msg.sender, address(this), _tokenId);
            emit Staked(msg.sender, _tokenId);
        }
    }

    // "UNSTAKE" function
    function unstake(uint _tokenId) public nonReentrant {
        Staker storage staker = stakers[msg.sender];
        require(tokenOwner[_tokenId] == msg.sender,"user must be the owner of the token");
        staker.unclaimedRewards += calculateRewards(msg.sender);
        staker.timeOfLastUpdate = block.timestamp;
        tokenOwner[_tokenId] = address(0);
        staker.amountStaked --;
        totalSupply --;
        removeByValue(_tokenId, staker.tokenIds);
        stakingToken.safeTransferFrom(address(this), msg.sender, _tokenId);
        emit Unstaked(msg.sender, _tokenId);
    }

    // "CLAIM" function
    function claimReward() public nonReentrant {
        Staker storage staker = stakers[msg.sender];
        uint rewards = calculateRewards(msg.sender) + staker.unclaimedRewards;
        require(rewards > 0,"You have no rewards to claim");
        require(block.timestamp - uint(staker.timeOfLastUpdate) != 0, "Too Early");
        require(rewards < rewardToken.balanceOf(address(this)), "Not enough tokens");
        staker.totalReward += rewards;
        staker.timeOfLastUpdate = block.timestamp;
        staker.unclaimedRewards = 0;
        rewardToken.transfer(msg.sender, rewards);
        emit RewardPaid(msg.sender, rewards);
    }

    // ------------------ View Functions ------------------ //

    function amountRewards() public view returns (uint) {
        Staker storage staker = stakers[msg.sender];
        uint reward;
        reward = staker.amountStaked * rewardTokenPerstakingToken;
        return reward;
    }

    function getStakedTokenIds(address _user) public view returns(uint[] memory tokenIds) {
        return stakers[_user].tokenIds;
    }

    // The total amount of HAN Token received as reward
    function getTotalReward(address _user) public view returns(uint) {
        return stakers[_user].totalReward;
    }

    // The accumulated amount of HAN token before "CLAIM"
    function getUnclaimedRewards(address _user) public view returns(uint) {
        return stakers[_user].unclaimedRewards;
    }

    // The amount of tokenId staked
    function getAmountStaked(address _user) public view returns(uint) {
        return stakers[_user].amountStaked;
    }

    // Last updated time by NFT tokenID
    function getTimeOfLastUpdate(address _user) public view returns(uint) {
        return stakers[_user].timeOfLastUpdate;
    }

    // ------------------ Private Functions ------------------ //
    
    // Reward amount check function
    function calculateRewards(address _user) private view returns (uint) {
        Staker storage staker = stakers[_user];
        uint reward;
        uint stakedTime = block.timestamp - staker.timeOfLastUpdate;
        reward = stakedTime * (staker.amountStaked * rewardTokenPerstakingToken);
        return reward;
    }

    function find(uint value, uint[] storage tokenIds) private view returns(uint)  {
        uint i = 0;
        while (tokenIds[i] != value) {
            i++;
        }
        return i;
    }

    function removeByValue(uint value, uint[] storage tokenIds) private{
        uint i = find(value, tokenIds);
        removeByIndex(i, tokenIds);
    }

    function removeByIndex(uint i, uint[] storage tokenIds) private{
        while (i < tokenIds.length - 1) {
            tokenIds[i] = tokenIds[i + 1];
            i++;
        }
        tokenIds.pop();
    }

    // ------------------ Event ------------------ //

    event Unstaked(address owner, uint tokenId);
    event Staked(address owner, uint tokenId);
    event RewardPaid(address indexed user, uint256 reward);
    event RecoveredERC20(address token, uint256 amount);
    event RecoveredERC721(address token, uint256 tokenId);
}