// SPDX-License-Identifier: MIT
// File: @openzeppelin/contracts/token/ERC721/IERC721Receiver.sol


// OpenZeppelin Contracts (last updated v5.0.0) (token/ERC721/IERC721Receiver.sol)

pragma solidity ^0.8.20;

/**
 * @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 (last updated v5.0.0) (token/ERC721/utils/ERC721Holder.sol)

pragma solidity ^0.8.20;


/**
 * @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}.
 */
abstract contract ERC721Holder is IERC721Receiver {
    /**
     * @dev See {IERC721Receiver-onERC721Received}.
     *
     * Always returns `IERC721Receiver.onERC721Received.selector`.
     */
    function onERC721Received(address, address, uint256, bytes memory) public virtual returns (bytes4) {
        return this.onERC721Received.selector;
    }
}

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


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

pragma solidity ^0.8.0;

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

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

// File: @openzeppelin/contracts/access/Ownable.sol


// OpenZeppelin Contracts (last updated v4.9.0) (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 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. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby disabling any functionality that is only available to the owner.
     */
    function renounceOwnership() public virtual onlyOwner {
        _transferOwnership(address(0));
    }

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

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

// File: @openzeppelin/contracts/utils/math/SignedMath.sol


// OpenZeppelin Contracts (last updated v4.8.0) (utils/math/SignedMath.sol)

pragma solidity ^0.8.0;

/**
 * @dev Standard signed math utilities missing in the Solidity language.
 */
library SignedMath {
    /**
     * @dev Returns the largest of two signed numbers.
     */
    function max(int256 a, int256 b) internal pure returns (int256) {
        return a > b ? a : b;
    }

    /**
     * @dev Returns the smallest of two signed numbers.
     */
    function min(int256 a, int256 b) internal pure returns (int256) {
        return a < b ? a : b;
    }

    /**
     * @dev Returns the average of two signed numbers without overflow.
     * The result is rounded towards zero.
     */
    function average(int256 a, int256 b) internal pure returns (int256) {
        // Formula from the book "Hacker's Delight"
        int256 x = (a & b) + ((a ^ b) >> 1);
        return x + (int256(uint256(x) >> 255) & (a ^ b));
    }

    /**
     * @dev Returns the absolute unsigned value of a signed value.
     */
    function abs(int256 n) internal pure returns (uint256) {
        unchecked {
            // must be unchecked in order to support `n = type(int256).min`
            return uint256(n >= 0 ? n : -n);
        }
    }
}

// File: @openzeppelin/contracts/utils/math/Math.sol


// OpenZeppelin Contracts (last updated v4.9.0) (utils/math/Math.sol)

pragma solidity ^0.8.0;

/**
 * @dev Standard math utilities missing in the Solidity language.
 */
library Math {
    enum Rounding {
        Down, // Toward negative infinity
        Up, // Toward infinity
        Zero // Toward zero
    }

    /**
     * @dev Returns the largest of two numbers.
     */
    function max(uint256 a, uint256 b) internal pure returns (uint256) {
        return a > b ? a : b;
    }

    /**
     * @dev Returns the smallest of two numbers.
     */
    function min(uint256 a, uint256 b) internal pure returns (uint256) {
        return a < b ? a : b;
    }

    /**
     * @dev Returns the average of two numbers. The result is rounded towards
     * zero.
     */
    function average(uint256 a, uint256 b) internal pure returns (uint256) {
        // (a + b) / 2 can overflow.
        return (a & b) + (a ^ b) / 2;
    }

    /**
     * @dev Returns the ceiling of the division of two numbers.
     *
     * This differs from standard division with `/` in that it rounds up instead
     * of rounding down.
     */
    function ceilDiv(uint256 a, uint256 b) internal pure returns (uint256) {
        // (a + b - 1) / b can overflow on addition, so we distribute.
        return a == 0 ? 0 : (a - 1) / b + 1;
    }

    /**
     * @notice Calculates floor(x * y / denominator) with full precision. Throws if result overflows a uint256 or denominator == 0
     * @dev Original credit to Remco Bloemen under MIT license (https://xn--2-umb.com/21/muldiv)
     * with further edits by Uniswap Labs also under MIT license.
     */
    function mulDiv(uint256 x, uint256 y, uint256 denominator) internal pure returns (uint256 result) {
        unchecked {
            // 512-bit multiply [prod1 prod0] = x * y. Compute the product mod 2^256 and mod 2^256 - 1, then use
            // use the Chinese Remainder Theorem to reconstruct the 512 bit result. The result is stored in two 256
            // variables such that product = prod1 * 2^256 + prod0.
            uint256 prod0; // Least significant 256 bits of the product
            uint256 prod1; // Most significant 256 bits of the product
            assembly {
                let mm := mulmod(x, y, not(0))
                prod0 := mul(x, y)
                prod1 := sub(sub(mm, prod0), lt(mm, prod0))
            }

            // Handle non-overflow cases, 256 by 256 division.
            if (prod1 == 0) {
                // Solidity will revert if denominator == 0, unlike the div opcode on its own.
                // The surrounding unchecked block does not change this fact.
                // See https://docs.soliditylang.org/en/latest/control-structures.html#checked-or-unchecked-arithmetic.
                return prod0 / denominator;
            }

            // Make sure the result is less than 2^256. Also prevents denominator == 0.
            require(denominator > prod1, "Math: mulDiv overflow");

            ///////////////////////////////////////////////
            // 512 by 256 division.
            ///////////////////////////////////////////////

            // Make division exact by subtracting the remainder from [prod1 prod0].
            uint256 remainder;
            assembly {
                // Compute remainder using mulmod.
                remainder := mulmod(x, y, denominator)

                // Subtract 256 bit number from 512 bit number.
                prod1 := sub(prod1, gt(remainder, prod0))
                prod0 := sub(prod0, remainder)
            }

            // Factor powers of two out of denominator and compute largest power of two divisor of denominator. Always >= 1.
            // See https://cs.stackexchange.com/q/138556/92363.

            // Does not overflow because the denominator cannot be zero at this stage in the function.
            uint256 twos = denominator & (~denominator + 1);
            assembly {
                // Divide denominator by twos.
                denominator := div(denominator, twos)

                // Divide [prod1 prod0] by twos.
                prod0 := div(prod0, twos)

                // Flip twos such that it is 2^256 / twos. If twos is zero, then it becomes one.
                twos := add(div(sub(0, twos), twos), 1)
            }

            // Shift in bits from prod1 into prod0.
            prod0 |= prod1 * twos;

            // Invert denominator mod 2^256. Now that denominator is an odd number, it has an inverse modulo 2^256 such
            // that denominator * inv = 1 mod 2^256. Compute the inverse by starting with a seed that is correct for
            // four bits. That is, denominator * inv = 1 mod 2^4.
            uint256 inverse = (3 * denominator) ^ 2;

            // Use the Newton-Raphson iteration to improve the precision. Thanks to Hensel's lifting lemma, this also works
            // in modular arithmetic, doubling the correct bits in each step.
            inverse *= 2 - denominator * inverse; // inverse mod 2^8
            inverse *= 2 - denominator * inverse; // inverse mod 2^16
            inverse *= 2 - denominator * inverse; // inverse mod 2^32
            inverse *= 2 - denominator * inverse; // inverse mod 2^64
            inverse *= 2 - denominator * inverse; // inverse mod 2^128
            inverse *= 2 - denominator * inverse; // inverse mod 2^256

            // Because the division is now exact we can divide by multiplying with the modular inverse of denominator.
            // This will give us the correct result modulo 2^256. Since the preconditions guarantee that the outcome is
            // less than 2^256, this is the final result. We don't need to compute the high bits of the result and prod1
            // is no longer required.
            result = prod0 * inverse;
            return result;
        }
    }

    /**
     * @notice Calculates x * y / denominator with full precision, following the selected rounding direction.
     */
    function mulDiv(uint256 x, uint256 y, uint256 denominator, Rounding rounding) internal pure returns (uint256) {
        uint256 result = mulDiv(x, y, denominator);
        if (rounding == Rounding.Up && mulmod(x, y, denominator) > 0) {
            result += 1;
        }
        return result;
    }

    /**
     * @dev Returns the square root of a number. If the number is not a perfect square, the value is rounded down.
     *
     * Inspired by Henry S. Warren, Jr.'s "Hacker's Delight" (Chapter 11).
     */
    function sqrt(uint256 a) internal pure returns (uint256) {
        if (a == 0) {
            return 0;
        }

        // For our first guess, we get the biggest power of 2 which is smaller than the square root of the target.
        //
        // We know that the "msb" (most significant bit) of our target number `a` is a power of 2 such that we have
        // `msb(a) <= a < 2*msb(a)`. This value can be written `msb(a)=2**k` with `k=log2(a)`.
        //
        // This can be rewritten `2**log2(a) <= a < 2**(log2(a) + 1)`
        // → `sqrt(2**k) <= sqrt(a) < sqrt(2**(k+1))`
        // → `2**(k/2) <= sqrt(a) < 2**((k+1)/2) <= 2**(k/2 + 1)`
        //
        // Consequently, `2**(log2(a) / 2)` is a good first approximation of `sqrt(a)` with at least 1 correct bit.
        uint256 result = 1 << (log2(a) >> 1);

        // At this point `result` is an estimation with one bit of precision. We know the true value is a uint128,
        // since it is the square root of a uint256. Newton's method converges quadratically (precision doubles at
        // every iteration). We thus need at most 7 iteration to turn our partial result with one bit of precision
        // into the expected uint128 result.
        unchecked {
            result = (result + a / result) >> 1;
            result = (result + a / result) >> 1;
            result = (result + a / result) >> 1;
            result = (result + a / result) >> 1;
            result = (result + a / result) >> 1;
            result = (result + a / result) >> 1;
            result = (result + a / result) >> 1;
            return min(result, a / result);
        }
    }

    /**
     * @notice Calculates sqrt(a), following the selected rounding direction.
     */
    function sqrt(uint256 a, Rounding rounding) internal pure returns (uint256) {
        unchecked {
            uint256 result = sqrt(a);
            return result + (rounding == Rounding.Up && result * result < a ? 1 : 0);
        }
    }

    /**
     * @dev Return the log in base 2, rounded down, of a positive value.
     * Returns 0 if given 0.
     */
    function log2(uint256 value) internal pure returns (uint256) {
        uint256 result = 0;
        unchecked {
            if (value >> 128 > 0) {
                value >>= 128;
                result += 128;
            }
            if (value >> 64 > 0) {
                value >>= 64;
                result += 64;
            }
            if (value >> 32 > 0) {
                value >>= 32;
                result += 32;
            }
            if (value >> 16 > 0) {
                value >>= 16;
                result += 16;
            }
            if (value >> 8 > 0) {
                value >>= 8;
                result += 8;
            }
            if (value >> 4 > 0) {
                value >>= 4;
                result += 4;
            }
            if (value >> 2 > 0) {
                value >>= 2;
                result += 2;
            }
            if (value >> 1 > 0) {
                result += 1;
            }
        }
        return result;
    }

    /**
     * @dev Return the log in base 2, following the selected rounding direction, of a positive value.
     * Returns 0 if given 0.
     */
    function log2(uint256 value, Rounding rounding) internal pure returns (uint256) {
        unchecked {
            uint256 result = log2(value);
            return result + (rounding == Rounding.Up && 1 << result < value ? 1 : 0);
        }
    }

    /**
     * @dev Return the log in base 10, rounded down, of a positive value.
     * Returns 0 if given 0.
     */
    function log10(uint256 value) internal pure returns (uint256) {
        uint256 result = 0;
        unchecked {
            if (value >= 10 ** 64) {
                value /= 10 ** 64;
                result += 64;
            }
            if (value >= 10 ** 32) {
                value /= 10 ** 32;
                result += 32;
            }
            if (value >= 10 ** 16) {
                value /= 10 ** 16;
                result += 16;
            }
            if (value >= 10 ** 8) {
                value /= 10 ** 8;
                result += 8;
            }
            if (value >= 10 ** 4) {
                value /= 10 ** 4;
                result += 4;
            }
            if (value >= 10 ** 2) {
                value /= 10 ** 2;
                result += 2;
            }
            if (value >= 10 ** 1) {
                result += 1;
            }
        }
        return result;
    }

    /**
     * @dev Return the log in base 10, following the selected rounding direction, of a positive value.
     * Returns 0 if given 0.
     */
    function log10(uint256 value, Rounding rounding) internal pure returns (uint256) {
        unchecked {
            uint256 result = log10(value);
            return result + (rounding == Rounding.Up && 10 ** result < value ? 1 : 0);
        }
    }

    /**
     * @dev Return the log in base 256, rounded down, of a positive value.
     * Returns 0 if given 0.
     *
     * Adding one to the result gives the number of pairs of hex symbols needed to represent `value` as a hex string.
     */
    function log256(uint256 value) internal pure returns (uint256) {
        uint256 result = 0;
        unchecked {
            if (value >> 128 > 0) {
                value >>= 128;
                result += 16;
            }
            if (value >> 64 > 0) {
                value >>= 64;
                result += 8;
            }
            if (value >> 32 > 0) {
                value >>= 32;
                result += 4;
            }
            if (value >> 16 > 0) {
                value >>= 16;
                result += 2;
            }
            if (value >> 8 > 0) {
                result += 1;
            }
        }
        return result;
    }

    /**
     * @dev Return the log in base 256, following the selected rounding direction, of a positive value.
     * Returns 0 if given 0.
     */
    function log256(uint256 value, Rounding rounding) internal pure returns (uint256) {
        unchecked {
            uint256 result = log256(value);
            return result + (rounding == Rounding.Up && 1 << (result << 3) < value ? 1 : 0);
        }
    }
}

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


// OpenZeppelin Contracts (last updated v4.9.0) (utils/Strings.sol)

pragma solidity ^0.8.0;



/**
 * @dev String operations.
 */
library Strings {
    bytes16 private constant _SYMBOLS = "0123456789abcdef";
    uint8 private constant _ADDRESS_LENGTH = 20;

    /**
     * @dev Converts a `uint256` to its ASCII `string` decimal representation.
     */
    function toString(uint256 value) internal pure returns (string memory) {
        unchecked {
            uint256 length = Math.log10(value) + 1;
            string memory buffer = new string(length);
            uint256 ptr;
            /// @solidity memory-safe-assembly
            assembly {
                ptr := add(buffer, add(32, length))
            }
            while (true) {
                ptr--;
                /// @solidity memory-safe-assembly
                assembly {
                    mstore8(ptr, byte(mod(value, 10), _SYMBOLS))
                }
                value /= 10;
                if (value == 0) break;
            }
            return buffer;
        }
    }

    /**
     * @dev Converts a `int256` to its ASCII `string` decimal representation.
     */
    function toString(int256 value) internal pure returns (string memory) {
        return string(abi.encodePacked(value < 0 ? "-" : "", toString(SignedMath.abs(value))));
    }

    /**
     * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation.
     */
    function toHexString(uint256 value) internal pure returns (string memory) {
        unchecked {
            return toHexString(value, Math.log256(value) + 1);
        }
    }

    /**
     * @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] = _SYMBOLS[value & 0xf];
            value >>= 4;
        }
        require(value == 0, "Strings: hex length insufficient");
        return string(buffer);
    }

    /**
     * @dev Converts an `address` with fixed length of 20 bytes to its not checksummed ASCII `string` hexadecimal representation.
     */
    function toHexString(address addr) internal pure returns (string memory) {
        return toHexString(uint256(uint160(addr)), _ADDRESS_LENGTH);
    }

    /**
     * @dev Returns true if the two strings are equal.
     */
    function equal(string memory a, string memory b) internal pure returns (bool) {
        return keccak256(bytes(a)) == keccak256(bytes(b));
    }
}

// File: @openzeppelin/contracts/utils/math/SafeMath.sol


// OpenZeppelin Contracts (last updated v4.9.0) (utils/math/SafeMath.sol)

pragma solidity ^0.8.0;

// CAUTION
// This version of SafeMath should only be used with Solidity 0.8 or later,
// because it relies on the compiler's built in overflow checks.

/**
 * @dev Wrappers over Solidity's arithmetic operations.
 *
 * NOTE: `SafeMath` is generally not needed starting with Solidity 0.8, since the compiler
 * now has built in overflow checking.
 */
library SafeMath {
    /**
     * @dev Returns the addition of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryAdd(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            uint256 c = a + b;
            if (c < a) return (false, 0);
            return (true, c);
        }
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function trySub(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            if (b > a) return (false, 0);
            return (true, a - b);
        }
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryMul(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
            // benefit is lost if 'b' is also tested.
            // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
            if (a == 0) return (true, 0);
            uint256 c = a * b;
            if (c / a != b) return (false, 0);
            return (true, c);
        }
    }

    /**
     * @dev Returns the division of two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryDiv(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            if (b == 0) return (false, 0);
            return (true, a / b);
        }
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryMod(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            if (b == 0) return (false, 0);
            return (true, a % b);
        }
    }

    /**
     * @dev Returns the addition of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `+` operator.
     *
     * Requirements:
     *
     * - Addition cannot overflow.
     */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        return a + b;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        return a - b;
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `*` operator.
     *
     * Requirements:
     *
     * - Multiplication cannot overflow.
     */
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        return a * b;
    }

    /**
     * @dev Returns the integer division of two unsigned integers, reverting on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator.
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        return a / b;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        return a % b;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {trySub}.
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        unchecked {
            require(b <= a, errorMessage);
            return a - b;
        }
    }

    /**
     * @dev Returns the integer division of two unsigned integers, reverting with custom message on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        unchecked {
            require(b > 0, errorMessage);
            return a / b;
        }
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting with custom message when dividing by zero.
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {tryMod}.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        unchecked {
            require(b > 0, errorMessage);
            return a % b;
        }
    }
}

// File: @openzeppelin/contracts/security/ReentrancyGuard.sol


// OpenZeppelin Contracts (last updated v4.9.0) (security/ReentrancyGuard.sol)

pragma solidity ^0.8.0;

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

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

    uint256 private _status;

    constructor() {
        _status = _NOT_ENTERED;
    }

    /**
     * @dev Prevents a contract from calling itself, directly or indirectly.
     * Calling a `nonReentrant` function from another `nonReentrant`
     * function is not supported. It is possible to prevent this from happening
     * by making the `nonReentrant` function external, and 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;
    }

    /**
     * @dev Returns true if the reentrancy guard is currently set to "entered", which indicates there is a
     * `nonReentrant` function in the call stack.
     */
    function _reentrancyGuardEntered() internal view returns (bool) {
        return _status == _ENTERED;
    }
}

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


// OpenZeppelin Contracts (last updated v4.9.0) (utils/Address.sol)

pragma solidity ^0.8.1;

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

        return account.code.length > 0;
    }

    /**
     * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
     * `recipient`, forwarding all available gas and reverting on errors.
     *
     * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
     * of certain opcodes, possibly making contracts go over the 2300 gas limit
     * imposed by `transfer`, making them unable to receive funds via
     * `transfer`. {sendValue} removes this limitation.
     *
     * https://consensys.net/diligence/blog/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/v0.8.0/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 functionCallWithValue(target, data, 0, "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");
        (bool success, bytes memory returndata) = target.call{value: value}(data);
        return verifyCallResultFromTarget(target, 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) {
        (bool success, bytes memory returndata) = target.staticcall(data);
        return verifyCallResultFromTarget(target, 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) {
        (bool success, bytes memory returndata) = target.delegatecall(data);
        return verifyCallResultFromTarget(target, success, returndata, errorMessage);
    }

    /**
     * @dev Tool to verify that a low level call to smart-contract was successful, and revert (either by bubbling
     * the revert reason or using the provided one) in case of unsuccessful call or if target was not a contract.
     *
     * _Available since v4.8._
     */
    function verifyCallResultFromTarget(
        address target,
        bool success,
        bytes memory returndata,
        string memory errorMessage
    ) internal view returns (bytes memory) {
        if (success) {
            if (returndata.length == 0) {
                // only check isContract if the call was successful and the return data is empty
                // otherwise we already know that it was a contract
                require(isContract(target), "Address: call to non-contract");
            }
            return returndata;
        } else {
            _revert(returndata, errorMessage);
        }
    }

    /**
     * @dev Tool to verify that a low level call was successful, and revert if it wasn't, either by bubbling the
     * revert reason or 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 {
            _revert(returndata, errorMessage);
        }
    }

    function _revert(bytes memory returndata, string memory errorMessage) private pure {
        // 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
            /// @solidity memory-safe-assembly
            assembly {
                let returndata_size := mload(returndata)
                revert(add(32, returndata), returndata_size)
            }
        } else {
            revert(errorMessage);
        }
    }
}

// File: @openzeppelin/contracts/token/ERC20/extensions/IERC20Permit.sol


// OpenZeppelin Contracts (last updated v4.9.0) (token/ERC20/extensions/IERC20Permit.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 Permit extension allowing approvals to be made via signatures, as defined in
 * https://eips.ethereum.org/EIPS/eip-2612[EIP-2612].
 *
 * Adds the {permit} method, which can be used to change an account's ERC20 allowance (see {IERC20-allowance}) by
 * presenting a message signed by the account. By not relying on {IERC20-approve}, the token holder account doesn't
 * need to send a transaction, and thus is not required to hold Ether at all.
 */
interface IERC20Permit {
    /**
     * @dev Sets `value` as the allowance of `spender` over ``owner``'s tokens,
     * given ``owner``'s signed approval.
     *
     * IMPORTANT: The same issues {IERC20-approve} has related to transaction
     * ordering also apply here.
     *
     * Emits an {Approval} event.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     * - `deadline` must be a timestamp in the future.
     * - `v`, `r` and `s` must be a valid `secp256k1` signature from `owner`
     * over the EIP712-formatted function arguments.
     * - the signature must use ``owner``'s current nonce (see {nonces}).
     *
     * For more information on the signature format, see the
     * https://eips.ethereum.org/EIPS/eip-2612#specification[relevant EIP
     * section].
     */
    function permit(
        address owner,
        address spender,
        uint256 value,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external;

    /**
     * @dev Returns the current nonce for `owner`. This value must be
     * included whenever a signature is generated for {permit}.
     *
     * Every successful call to {permit} increases ``owner``'s nonce by one. This
     * prevents a signature from being used multiple times.
     */
    function nonces(address owner) external view returns (uint256);

    /**
     * @dev Returns the domain separator used in the encoding of the signature for {permit}, as defined by {EIP712}.
     */
    // solhint-disable-next-line func-name-mixedcase
    function DOMAIN_SEPARATOR() external view returns (bytes32);
}

// File: @openzeppelin/contracts/token/ERC20/IERC20.sol


// OpenZeppelin Contracts (last updated v4.9.0) (token/ERC20/IERC20.sol)

pragma solidity ^0.8.0;

/**
 * @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/token/ERC20/utils/SafeERC20.sol


// OpenZeppelin Contracts (last updated v4.9.3) (token/ERC20/utils/SafeERC20.sol)

pragma solidity ^0.8.0;




/**
 * @title SafeERC20
 * @dev Wrappers around ERC20 operations that throw on failure (when the token
 * contract returns false). Tokens that return no value (and instead revert or
 * throw on failure) are also supported, non-reverting calls are assumed to be
 * successful.
 * To use this library you can add a `using SafeERC20 for IERC20;` statement to your contract,
 * which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
 */
library SafeERC20 {
    using Address for address;

    /**
     * @dev Transfer `value` amount of `token` from the calling contract to `to`. If `token` returns no value,
     * non-reverting calls are assumed to be successful.
     */
    function safeTransfer(IERC20 token, address to, uint256 value) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
    }

    /**
     * @dev Transfer `value` amount of `token` from `from` to `to`, spending the approval given by `from` to the
     * calling contract. If `token` returns no value, non-reverting calls are assumed to be successful.
     */
    function safeTransferFrom(IERC20 token, address from, address to, uint256 value) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transferFrom.selector, from, to, value));
    }

    /**
     * @dev Deprecated. This function has issues similar to the ones found in
     * {IERC20-approve}, and its usage is discouraged.
     *
     * Whenever possible, use {safeIncreaseAllowance} and
     * {safeDecreaseAllowance} instead.
     */
    function safeApprove(IERC20 token, address spender, uint256 value) internal {
        // safeApprove should only be called when setting an initial allowance,
        // or when resetting it to zero. To increase and decrease it, use
        // 'safeIncreaseAllowance' and 'safeDecreaseAllowance'
        require(
            (value == 0) || (token.allowance(address(this), spender) == 0),
            "SafeERC20: approve from non-zero to non-zero allowance"
        );
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, value));
    }

    /**
     * @dev Increase the calling contract's allowance toward `spender` by `value`. If `token` returns no value,
     * non-reverting calls are assumed to be successful.
     */
    function safeIncreaseAllowance(IERC20 token, address spender, uint256 value) internal {
        uint256 oldAllowance = token.allowance(address(this), spender);
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, oldAllowance + value));
    }

    /**
     * @dev Decrease the calling contract's allowance toward `spender` by `value`. If `token` returns no value,
     * non-reverting calls are assumed to be successful.
     */
    function safeDecreaseAllowance(IERC20 token, address spender, uint256 value) internal {
        unchecked {
            uint256 oldAllowance = token.allowance(address(this), spender);
            require(oldAllowance >= value, "SafeERC20: decreased allowance below zero");
            _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, oldAllowance - value));
        }
    }

    /**
     * @dev Set the calling contract's allowance toward `spender` to `value`. If `token` returns no value,
     * non-reverting calls are assumed to be successful. Meant to be used with tokens that require the approval
     * to be set to zero before setting it to a non-zero value, such as USDT.
     */
    function forceApprove(IERC20 token, address spender, uint256 value) internal {
        bytes memory approvalCall = abi.encodeWithSelector(token.approve.selector, spender, value);

        if (!_callOptionalReturnBool(token, approvalCall)) {
            _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, 0));
            _callOptionalReturn(token, approvalCall);
        }
    }

    /**
     * @dev Use a ERC-2612 signature to set the `owner` approval toward `spender` on `token`.
     * Revert on invalid signature.
     */
    function safePermit(
        IERC20Permit token,
        address owner,
        address spender,
        uint256 value,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) internal {
        uint256 nonceBefore = token.nonces(owner);
        token.permit(owner, spender, value, deadline, v, r, s);
        uint256 nonceAfter = token.nonces(owner);
        require(nonceAfter == nonceBefore + 1, "SafeERC20: permit did not succeed");
    }

    /**
     * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
     * on the return value: the return value is optional (but if data is returned, it must not be false).
     * @param token The token targeted by the call.
     * @param data The call data (encoded using abi.encode or one of its variants).
     */
    function _callOptionalReturn(IERC20 token, bytes memory data) private {
        // We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
        // we're implementing it ourselves. We use {Address-functionCall} to perform this call, which verifies that
        // the target address contains contract code and also asserts for success in the low-level call.

        bytes memory returndata = address(token).functionCall(data, "SafeERC20: low-level call failed");
        require(returndata.length == 0 || abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
    }

    /**
     * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
     * on the return value: the return value is optional (but if data is returned, it must not be false).
     * @param token The token targeted by the call.
     * @param data The call data (encoded using abi.encode or one of its variants).
     *
     * This is a variant of {_callOptionalReturn} that silents catches all reverts and returns a bool instead.
     */
    function _callOptionalReturnBool(IERC20 token, bytes memory data) private returns (bool) {
        // We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
        // we're implementing it ourselves. We cannot use {Address-functionCall} here since this should return false
        // and not revert is the subcall reverts.

        (bool success, bytes memory returndata) = address(token).call(data);
        return
            success && (returndata.length == 0 || abi.decode(returndata, (bool))) && Address.isContract(address(token));
    }
}

// File: contracts/MCDStaking.sol


pragma solidity ^0.8.18;








interface NFT {
    function transferFrom(address sender, address receiver, uint256 tokenID) external;
}

contract MCDStaking is ERC721Holder, Ownable, ReentrancyGuard {
    
    using Strings for uint256;
    using SafeMath for uint256;
    using SafeERC20 for IERC20;

    address public immutable mcd = 0x13E0c7f86E28372D5FE7d9F002045e10eB288CF7;
    address public immutable treasury = 0xA682182447D462dc980a4d0CD0e81D0c4B6a235C;

    uint256 private immutable genesisMigrationDate = 1710777600;
    uint256 private constant genesisLockPeriod = 150 days;

    uint256 private constant mcdPercent = 70;
    uint256 private constant xmcdPercent = 30;
    uint256 private constant divider = 100;

    uint256 private constant timeStep = 1 days;
    uint256 private constant vestingPeriod = 90 days;

    uint256 public immutable stakingStart = 1711382400;
    uint256 public lastLiquidityRelease;

    uint256 public tokenEmission = 300000e18;
    uint256 public totalCollection = 2;
    uint256 public totalHashpower;

    struct StakeInfo {
        uint256 collectionID;
        address nftAddr;
        uint256 tokenID;
        uint256 stakeTime;
        uint256 hashpower;
        uint256 lastClaimTime;
        bool staked;
    }

    struct UserData {
        uint256 xMCD;
        uint256 hashpower;
    }

    mapping(address=>StakeInfo[]) public stakeInfo;
    mapping(address=>UserData) public userData;
    mapping(address=>bool) private admin;
    mapping(address=>uint256) public nftHashpower;
    mapping(uint256=>address) public nftContract;
    mapping(address=>uint256) public genesisMigratedToken;
    mapping(address=>mapping(uint256=>bool)) public stakedNFT;

    event Stake(address user, address nftAddr, uint256 tokenID, uint256 timestamp);
    event BatchStake(address user, address nftAddr, uint256[] tokenIDs, uint256 timestamp);
    event Unstake(address user, address nftAddr, uint256 tokenID, uint256 timestamp);
    event ClaimSingleNFTYield(address user, address nftAddr, uint256 tokenID, uint256 timestamp, uint256 totalYield);
    event ClaimAll(address user, uint256 timestamp, uint256 mcdEarned, uint256 xmcdEarned);
    event TransferXMCD(address sender, address receiver, uint256 transferAmount, uint256 timestamp);
    event DebitXMCD(address spender, uint256 spendAmount, uint256 timestamp);
    event CreditXMCD(address adminAddr, address receiver, uint256 creditAmount, uint256 timestamp);
    event GenesisStakeMigrate(address adminAddr, address holderWallet, uint256 tokenID, uint256 startTime, uint256 lastClaim);
    event GenesisStakeBatchMigrate(address adminAddr, address[] wallet, uint256[] tokenIDs, uint256 startTime, uint256 lastClaim);
    event GenesisTokenMigrate(address adminAddr, address receiver, uint256 amount);
    event GenesisTokenBatchMigrate(address adminAddr, address[] receiver, uint256[] amount);
    event GenesisTokenClaim(address user, uint256 mcdEarned, uint256 xmcdEarned, uint256 timestamp);
    event ReleaseToTreasury(address caller, uint256 unreleasedDays, uint256 releasedAmount, uint256 timestamp);
    event SetTokenEmission(address adminAddr, uint256 newEmission, uint256 timestamp);
    event AddNFTContract(address adminAddr, uint256 collectionID, address nftAddr, uint256 timestamp);
    event ManageAdmin(address newAdminAddr, bool state, uint256 timestamp);
    event UpdateNFTHashpower(address adminAddr, uint256 oldPower, uint256 newPower, uint256 timestamp);
    event SetGenesisContractAddr(address adminAddr, address genesisAddr, uint256 timestamp);

    constructor(
    ) {
        lastLiquidityRelease = block.timestamp;
        nftContract[1] = 0xeB248E38eC67DbE9Cc3DC82bB5eD6d1681939CD8;
        nftHashpower[nftContract[1]] = 20;
    }

    function stake(uint256 _collectionID, uint256 _tokenID) external nonReentrant {
        address nftAddr = nftContract[_collectionID];
        require(nftAddr != address(0), "Cannot be null address.");
        require(!stakedNFT[nftAddr][_tokenID], "This NFT is already staked.");
        stakeInfo[msg.sender].push(StakeInfo(_collectionID,nftAddr,_tokenID,block.timestamp,nftHashpower[nftAddr],block.timestamp,true));
        userData[msg.sender].hashpower += nftHashpower[nftAddr];
        totalHashpower += nftHashpower[nftAddr];
        stakedNFT[nftAddr][_tokenID] = true;
        NFT(nftAddr).transferFrom(msg.sender, address(this), _tokenID);
        emit Stake(msg.sender, nftAddr, _tokenID, block.timestamp);
    }

    function batchStake(uint256 _collectionID, uint256[] memory _tokenIDs) external nonReentrant {
        address nftAddr = nftContract[_collectionID];
        require(nftAddr != address(0), "Cannot be null address.");
        uint256 hashPowerIncrease = nftHashpower[nftAddr]*_tokenIDs.length;
        userData[msg.sender].hashpower += hashPowerIncrease;
        totalHashpower += hashPowerIncrease;
        uint256 tokensCount = _tokenIDs.length;
        for (uint256 i; i < tokensCount;) {
            require(!stakedNFT[nftAddr][_tokenIDs[i]], "One of the NFTs is already staked.");
            stakeInfo[msg.sender].push(StakeInfo(_collectionID,nftAddr,_tokenIDs[i],block.timestamp,nftHashpower[nftAddr],block.timestamp,true));
            stakedNFT[nftAddr][_tokenIDs[i]] = true;
            NFT(nftAddr).transferFrom(msg.sender, address(this), _tokenIDs[i]);
            unchecked {
                ++i;
            }
        }
        emit BatchStake(msg.sender, nftAddr, _tokenIDs, block.timestamp);
    }

    function unstake(uint256 _collectionID, uint256 _tokenID) external nonReentrant {
        uint256 hashpowerDecrease;
        uint256 stakingRecords = stakeInfo[msg.sender].length;
        address nftAddr = nftContract[_collectionID];
        for (uint256 i; i < stakingRecords;) {
            if (stakeInfo[msg.sender][i].tokenID == _tokenID && stakeInfo[msg.sender][i].collectionID == _collectionID && stakeInfo[msg.sender][i].staked) {
                uint256 mcdMined = getTokenYield(msg.sender, _collectionID, _tokenID);
                if (block.timestamp >= stakeInfo[msg.sender][i].stakeTime + vestingPeriod) {
                    uint256 earnedMCD = mcdMined * mcdPercent / divider;
                    uint256 earnedXMCD = mcdMined - earnedMCD;
                    userData[msg.sender].xMCD += earnedXMCD;
                    IERC20(mcd).safeTransfer(msg.sender, earnedMCD);
                } else {
                    IERC20(mcd).safeTransfer(treasury, mcdMined);
                }
                stakeInfo[msg.sender][i].lastClaimTime = block.timestamp;
                stakeInfo[msg.sender][i].staked = false;
                userData[msg.sender].hashpower -= stakeInfo[msg.sender][i].hashpower;
                hashpowerDecrease += stakeInfo[msg.sender][i].hashpower;
                stakedNFT[nftAddr][_tokenID] = false;
                NFT(nftAddr).transferFrom(address(this), msg.sender, _tokenID);
                break;
            }
            unchecked {
                ++i;
            }
        }
        totalHashpower -= hashpowerDecrease;
        emit Unstake(msg.sender, nftAddr, _tokenID, block.timestamp);
    }

    function claimSingleNFTYield(uint256 _collectionID, uint256 _tokenID) external nonReentrant {
        uint256 stakingRecords = stakeInfo[msg.sender].length;
        for (uint256 i; i < stakingRecords;) {
            if (stakeInfo[msg.sender][i].tokenID == _tokenID && stakeInfo[msg.sender][i].collectionID == _collectionID && stakeInfo[msg.sender][i].staked) {
                require(block.timestamp >= stakeInfo[msg.sender][i].lastClaimTime + timeStep, "Not yet 1 day since last claim.");
                if (block.timestamp >= stakeInfo[msg.sender][i].stakeTime + vestingPeriod) {
                    uint256 mcdMined = getTokenYield(msg.sender, _collectionID, _tokenID);
                    require(mcdMined > 0, "Nothing to be claimed.");
                    uint256 earnedMCD = mcdMined * mcdPercent / divider;
                    uint256 earnedXMCD = mcdMined - earnedMCD;
                    userData[msg.sender].xMCD += earnedXMCD;
                    stakeInfo[msg.sender][i].lastClaimTime = block.timestamp;
                    IERC20(mcd).safeTransfer(msg.sender, earnedMCD);
                }
                break;
            }
            unchecked {
                ++i;
            }
        }
        emit ClaimSingleNFTYield(msg.sender, nftContract[_collectionID], _tokenID, block.timestamp, getTokenYield(msg.sender, _collectionID, _tokenID));
    }

    function claimAll() external nonReentrant {
        uint256 totalYield;
        uint256 stakingRecords = stakeInfo[msg.sender].length;
        for (uint256 i; i < stakingRecords;) {
            if (stakeInfo[msg.sender][i].staked && block.timestamp >= stakeInfo[msg.sender][i].stakeTime + vestingPeriod) {
                if (block.timestamp >= stakeInfo[msg.sender][i].lastClaimTime + timeStep) {
                    uint256 mcdMined = getTokenYield(msg.sender, stakeInfo[msg.sender][i].collectionID, stakeInfo[msg.sender][i].tokenID);
                    totalYield += mcdMined;
                    stakeInfo[msg.sender][i].lastClaimTime = block.timestamp;
                }
            }
            unchecked {
                ++i;
            }
        }
        require(totalYield > 0, "Nothing to be claimed.");
        uint256 earnedMCD = totalYield * mcdPercent / divider;
        uint256 earnedXMCD = totalYield - earnedMCD;
        userData[msg.sender].xMCD += earnedXMCD;
        IERC20(mcd).safeTransfer(msg.sender, earnedMCD);
        emit ClaimAll(msg.sender, block.timestamp, earnedMCD, earnedXMCD);
    }

    function getTokenYield(address _wallet, uint256 _collectionID, uint256 _tokenID) public view returns (uint256) {
        uint256 yield;
        uint256 stakingRecords = stakeInfo[_wallet].length;
        for (uint256 i; i < stakingRecords;) {
            if (stakeInfo[_wallet][i].tokenID == _tokenID && stakeInfo[_wallet][i].collectionID == _collectionID && stakeInfo[_wallet][i].staked) {
                uint256 stakedPeriod = block.timestamp - stakeInfo[_wallet][i].lastClaimTime;
                uint256 fullDayCount = stakedPeriod/timeStep;
                yield = (tokenEmission*stakeInfo[_wallet][i].hashpower*fullDayCount/totalHashpower/30);
                break;
            }
            if (i >= 20000) break;
            unchecked {
                ++i;
            }
        }
        return yield;
    }

    function getTotalTokenYield(address _wallet) public view returns (uint256) {
        uint256 totalYield = 0;
        uint256 stakingRecords = stakeInfo[_wallet].length;
        for (uint256 i; i < stakingRecords;) {
            if (stakeInfo[_wallet][i].staked) {
                uint256 stakedPeriod = block.timestamp - stakeInfo[_wallet][i].lastClaimTime;
                uint256 fullDayCount = stakedPeriod/timeStep;
                totalYield += (tokenEmission*stakeInfo[_wallet][i].hashpower*fullDayCount/totalHashpower/30);
            }
            if (i >= 20000) break;
            unchecked {
                ++i;
            }
        }
        return totalYield;
    }

    function getTotalClaimable(address _wallet) public view returns (uint256) {
        uint256 totalClaimable = 0;
        uint256 stakingRecords = stakeInfo[_wallet].length;
        for (uint256 i; i < stakingRecords;) {
            if (stakeInfo[_wallet][i].staked && block.timestamp >= stakeInfo[msg.sender][i].stakeTime + vestingPeriod) {
                uint256 stakedPeriod = block.timestamp - stakeInfo[_wallet][i].lastClaimTime;
                uint256 fullDayCount = stakedPeriod/timeStep;
                totalClaimable += (tokenEmission*stakeInfo[_wallet][i].hashpower*fullDayCount/totalHashpower/30);
            }
            if (i >= 20000) break;
            unchecked {
                ++i;
            }
        }
        return totalClaimable;
    }

    function getCurDay() public view returns (uint256) {
        return (block.timestamp - stakingStart) / timeStep;
    }

    function transferXMCD(address _receiver, uint256 _transferAmount) external {
        require(_receiver != address(0), "Receiver cannot be null address.");
        require(userData[msg.sender].xMCD >= _transferAmount, "User insufficient xMCD balance.");
        userData[msg.sender].xMCD -= _transferAmount;
        userData[_receiver].xMCD += _transferAmount;
        emit TransferXMCD(msg.sender, _receiver, _transferAmount, block.timestamp);
    }

    function debitXMCD(address _spender, uint256 _debitAmount) external {
        require(admin[msg.sender] || msg.sender == owner(), "Only admin or owner can execute.");
        require(_spender != address(0), "Spender cannot be null address.");
        require(_debitAmount > 0, "Debit amount cannot be zero.");
        require(userData[_spender].xMCD >= _debitAmount, "User insufficient xMCD balance.");
        userData[_spender].xMCD -= _debitAmount;
        emit DebitXMCD(msg.sender, _debitAmount, block.timestamp);
    }

    function creditXMCD(address _receiver, uint256 _creditAmount) external {
        require(admin[msg.sender] || msg.sender == owner(), "Only admin or owner can execute.");
        require(_receiver != address(0), "Receiver cannot be null address.");
        require(_creditAmount > 0, "Credit amount cannot be zero.");
        userData[_receiver].xMCD += _creditAmount;
        emit CreditXMCD(msg.sender, _receiver, _creditAmount, block.timestamp);
    }

    function genesisStakeMigrate(address _wallet, uint256 _tokenID, uint256 _startTime, uint256 _lastClaim) external {
        require(admin[msg.sender] || msg.sender == owner(), "Only admin or owner can execute.");
        require(_wallet != address(0), "Cannot migrate to null address.");
        require(!stakedNFT[nftContract[0]][_tokenID], "This NFT is already staked.");
        require(_startTime > 0 && _lastClaim > 0, "Timestamp cannot be zero.");
        require(_startTime >= stakingStart, "Timestamp must be greater than staking start time.");
        require(_lastClaim >= _startTime, "Invalid last claim timestamp.");
        stakeInfo[_wallet].push(StakeInfo(0,nftContract[0],_tokenID,_startTime,nftHashpower[nftContract[0]],_lastClaim,true));
        userData[_wallet].hashpower += nftHashpower[nftContract[0]];
        totalHashpower += nftHashpower[nftContract[0]];
        stakedNFT[nftContract[0]][_tokenID] = true;
        emit GenesisStakeMigrate(msg.sender, _wallet, _tokenID, _startTime, _lastClaim);
    }

    function genesisStakeBatchMigrate(address[] memory _wallet, uint256[] memory _tokenIDs, uint256 _startTime, uint256 _lastClaim) external {
        require(admin[msg.sender] || msg.sender == owner(), "Only admin or owner can execute.");
        require(_wallet.length == _tokenIDs.length, "Unmatched data for wallet and token IDs.");
        require(_startTime > 0 && _lastClaim > 0, "Timestamp cannot be zero.");
        require(_startTime >= stakingStart, "Timestamp must be greater than staking start time.");
        require(_lastClaim >= _startTime, "Invalid last claim timestamp.");
        uint256 hashpowerIncreaseCount;
        uint256 walletCount = _wallet.length;
        for (uint256 i; i < walletCount;) {
            if (_wallet[i] != address(0)) {
                require(!stakedNFT[nftContract[0]][_tokenIDs[i]], "One of the NFTs is already staked.");
                stakeInfo[_wallet[i]].push(StakeInfo(0,nftContract[0],_tokenIDs[i],_startTime,nftHashpower[nftContract[0]],_lastClaim,true));
                userData[_wallet[i]].hashpower += nftHashpower[nftContract[0]];
                hashpowerIncreaseCount++;
                stakedNFT[nftContract[0]][_tokenIDs[i]] = true;
            }
            unchecked {
                ++i;
            }
        }
        totalHashpower += (nftHashpower[nftContract[0]]*hashpowerIncreaseCount);
        emit GenesisStakeBatchMigrate(msg.sender, _wallet, _tokenIDs, _startTime, _lastClaim);
    }

    function genesisTokenMigrate(address _wallet, uint256 _amount) external {
        require(admin[msg.sender] || msg.sender == owner(), "Only admin or owner can execute.");
        require(_wallet != address(0), "Cannot migrate to null address.");
        genesisMigratedToken[_wallet] = _amount;
        emit GenesisTokenMigrate(msg.sender, _wallet, _amount);
    }

    function genesisTokenBatchMigrate(address[] memory _wallet, uint256[] memory _amount) external {
        require(admin[msg.sender] || msg.sender == owner(), "Only admin or owner can execute.");
        require(_wallet.length == _amount.length, "Unmatched data for wallet and amount.");
        uint256 walletCount = _wallet.length;
        for (uint256 i; i < walletCount;) {
            if (_wallet[i] != address(0)) {
                genesisMigratedToken[_wallet[i]] = _amount[i];
            }
            unchecked {
                ++i;
            }
        }
        emit GenesisTokenBatchMigrate(msg.sender, _wallet, _amount);
    }

    function genesisTokenClaim() external nonReentrant {
        require(genesisMigratedToken[msg.sender] > 0, "No migrated token can be claimed.");
        require(block.timestamp >= genesisMigrationDate + genesisLockPeriod, "Migrated tokens still under locking period.");
        uint256 unlockedMCD = genesisMigratedToken[msg.sender] * mcdPercent / divider;
        uint256 earnedXMCD = genesisMigratedToken[msg.sender] - unlockedMCD;
        userData[msg.sender].xMCD += earnedXMCD;
        genesisMigratedToken[msg.sender] = 0;
        IERC20(mcd).safeTransfer(msg.sender, unlockedMCD);
        emit GenesisTokenClaim(msg.sender, unlockedMCD, earnedXMCD, block.timestamp);
    }

    function releaseToTreasury() external nonReentrant {
        require(block.timestamp >= lastLiquidityRelease + timeStep, "Not yet 24 hours since last released.");
        require(totalHashpower > 0, "No NFT is staked for mining.");
        uint256 releasableDays = (block.timestamp-lastLiquidityRelease)/timeStep;
        uint256 releasableMCD = tokenEmission*releasableDays*xmcdPercent/divider/30;
        lastLiquidityRelease += (releasableDays*timeStep);
        IERC20(mcd).safeTransfer(treasury, releasableMCD);
        emit ReleaseToTreasury(msg.sender, releasableDays, releasableMCD, block.timestamp);
    }

    function setTokenEmission(uint256 _newEmission) external {
        require(admin[msg.sender] || msg.sender == owner(), "Only admins or owner can execute.");
        tokenEmission = _newEmission;
        emit SetTokenEmission(msg.sender, _newEmission, block.timestamp);
    }

    function addNFTContract(address _contract, uint256 _power) external onlyOwner {
        require(_contract != address(0), "Cannot add null address.");
        require(_power > 0, "Power cannot be zero.");
        nftContract[totalCollection] = _contract;
        nftHashpower[_contract] = _power;
        totalCollection++;
        emit AddNFTContract(msg.sender, totalCollection, _contract, block.timestamp);
    }

    function manageAdmin(address _adminAddr, bool _state) external onlyOwner {
        require(_adminAddr != address(0), "Cannot add null address.");
        admin[_adminAddr] = _state;
        emit ManageAdmin(_adminAddr, _state, block.timestamp);
    }

    function updateNFTHashpower(address _nftContract, uint256 _power) external onlyOwner {
        require(_nftContract != address(0), "Invalid contract address.");
        uint256 oldPower = nftHashpower[_nftContract];
        nftHashpower[_nftContract] = _power;
        emit UpdateNFTHashpower(msg.sender, oldPower, _power, block.timestamp);
    }

    function setGenesisContractAddr(address _genesisContract) external onlyOwner {
        require(nftContract[0] == address(0), "Genesis contract already set.");
        nftContract[0] = _genesisContract;
        nftHashpower[nftContract[0]] = 100;
        emit SetGenesisContractAddr(msg.sender, _genesisContract, block.timestamp);
    }

    function getUserStakingInfo(address _userAddr) external view returns(StakeInfo[] memory) {
        return stakeInfo[_userAddr];
    }

    function getUserData(address _userAddr) external view returns(UserData memory) {
        return userData[_userAddr];
    }

}