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



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.0) (access/Ownable.sol)

pragma solidity ^0.8.0;

import "../utils/Context.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. 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/token/ERC20/extensions/IERC20Permit.sol



// SPDX-License-Identifier: MIT
// 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



// SPDX-License-Identifier: MIT
// 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



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.3) (token/ERC20/utils/SafeERC20.sol)

pragma solidity ^0.8.0;

import "../IERC20.sol";
import "../extensions/IERC20Permit.sol";
import "../../../utils/Address.sol";

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



// SPDX-License-Identifier: MIT
// 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/utils/Context.sol



// SPDX-License-Identifier: MIT
// 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/utils/math/SafeMath.sol



// SPDX-License-Identifier: MIT
// 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: contracts/Library/DateTime.sol



// SPDX-License-Identifier: UNLICENSED
pragma solidity ^0.8.9;

contract DateTime {
    /*
     *  Date and Time utilities for ethereum contracts
     *
     */
    struct _DateTime {
        uint16 year;
        uint8 month;
        uint8 day;
        uint8 hour;
        uint8 minute;
        uint8 second;
        uint8 weekday;
    }

    uint constant DAY_IN_SECONDS = 86400;
    uint constant YEAR_IN_SECONDS = 31536000;
    uint constant LEAP_YEAR_IN_SECONDS = 31622400;

    uint constant HOUR_IN_SECONDS = 3600;
    uint constant MINUTE_IN_SECONDS = 60;

    uint16 constant ORIGIN_YEAR = 1970;

    function isLeapYear(uint16 year) public pure returns (bool) {
        if (year % 4 != 0) {
            return false;
        }
        if (year % 100 != 0) {
            return true;
        }
        if (year % 400 != 0) {
            return false;
        }
        return true;
    }

    function leapYearsBefore(uint year) public pure returns (uint) {
        year -= 1;
        return year / 4 - year / 100 + year / 400;
    }

    function getDaysInMonth(
        uint8 month,
        uint16 year
    ) public pure returns (uint8) {
        if (
            month == 1 ||
            month == 3 ||
            month == 5 ||
            month == 7 ||
            month == 8 ||
            month == 10 ||
            month == 12
        ) {
            return 31;
        } else if (month == 4 || month == 6 || month == 9 || month == 11) {
            return 30;
        } else if (isLeapYear(year)) {
            return 29;
        } else {
            return 28;
        }
    }

    function parseTimestamp(
        uint timestamp
    ) internal pure returns (_DateTime memory dt) {
        uint secondsAccountedFor = 0;
        uint buf;
        uint8 i;

        // Year
        dt.year = getYear(timestamp);
        buf = leapYearsBefore(dt.year) - leapYearsBefore(ORIGIN_YEAR);

        secondsAccountedFor += LEAP_YEAR_IN_SECONDS * buf;
        secondsAccountedFor += YEAR_IN_SECONDS * (dt.year - ORIGIN_YEAR - buf);

        // Month
        uint secondsInMonth;
        for (i = 1; i <= 12; i++) {
            secondsInMonth = DAY_IN_SECONDS * getDaysInMonth(i, dt.year);
            if (secondsInMonth + secondsAccountedFor > timestamp) {
                dt.month = i;
                break;
            }
            secondsAccountedFor += secondsInMonth;
        }

        // Day
        for (i = 1; i <= getDaysInMonth(dt.month, dt.year); i++) {
            if (DAY_IN_SECONDS + secondsAccountedFor > timestamp) {
                dt.day = i;
                break;
            }
            secondsAccountedFor += DAY_IN_SECONDS;
        }

        // Hour
        dt.hour = getHour(timestamp);

        // Minute
        dt.minute = getMinute(timestamp);

        // Second
        dt.second = getSecond(timestamp);

        // Day of week.
        dt.weekday = getWeekday(timestamp);
    }

    function getYear(uint timestamp) public pure returns (uint16) {
        uint secondsAccountedFor = 0;
        uint16 year;
        uint numLeapYears;

        // Year
        year = uint16(ORIGIN_YEAR + timestamp / YEAR_IN_SECONDS);
        numLeapYears = leapYearsBefore(year) - leapYearsBefore(ORIGIN_YEAR);

        secondsAccountedFor += LEAP_YEAR_IN_SECONDS * numLeapYears;
        secondsAccountedFor +=
            YEAR_IN_SECONDS *
            (year - ORIGIN_YEAR - numLeapYears);

        while (secondsAccountedFor > timestamp) {
            if (isLeapYear(uint16(year - 1))) {
                secondsAccountedFor -= LEAP_YEAR_IN_SECONDS;
            } else {
                secondsAccountedFor -= YEAR_IN_SECONDS;
            }
            year -= 1;
        }
        return year;
    }

    function getMonth(uint timestamp) public pure returns (uint8) {
        return parseTimestamp(timestamp).month;
    }

    function getDay(uint timestamp) public pure returns (uint8) {
        return parseTimestamp(timestamp).day;
    }

    function getHour(uint timestamp) public pure returns (uint8) {
        return uint8((timestamp / 60 / 60) % 24);
    }

    function getMinute(uint timestamp) public pure returns (uint8) {
        return uint8((timestamp / 60) % 60);
    }

    function getSecond(uint timestamp) public pure returns (uint8) {
        return uint8(timestamp % 60);
    }

    function getWeekday(uint timestamp) public pure returns (uint8) {
        return uint8((timestamp / DAY_IN_SECONDS + 4) % 7);
    }

    function toTimestamp(
        uint16 year,
        uint8 month,
        uint8 day
    ) public pure returns (uint timestamp) {
        return toTimestamp(year, month, day, 0, 0, 0);
    }

    function toTimestamp(
        uint16 year,
        uint8 month,
        uint8 day,
        uint8 hour
    ) public pure returns (uint timestamp) {
        return toTimestamp(year, month, day, hour, 0, 0);
    }

    function toTimestamp(
        uint16 year,
        uint8 month,
        uint8 day,
        uint8 hour,
        uint8 minute
    ) public pure returns (uint timestamp) {
        return toTimestamp(year, month, day, hour, minute, 0);
    }

    function toTimestamp(
        uint16 year,
        uint8 month,
        uint8 day,
        uint8 hour,
        uint8 minute,
        uint8 second
    ) public pure returns (uint timestamp) {
        uint16 i;

        // Year
        for (i = ORIGIN_YEAR; i < year; i++) {
            if (isLeapYear(i)) {
                timestamp += LEAP_YEAR_IN_SECONDS;
            } else {
                timestamp += YEAR_IN_SECONDS;
            }
        }

        // Month
        uint8[12] memory monthDayCounts;
        monthDayCounts[0] = 31;
        if (isLeapYear(year)) {
            monthDayCounts[1] = 29;
        } else {
            monthDayCounts[1] = 28;
        }
        monthDayCounts[2] = 31;
        monthDayCounts[3] = 30;
        monthDayCounts[4] = 31;
        monthDayCounts[5] = 30;
        monthDayCounts[6] = 31;
        monthDayCounts[7] = 31;
        monthDayCounts[8] = 30;
        monthDayCounts[9] = 31;
        monthDayCounts[10] = 30;
        monthDayCounts[11] = 31;

        for (i = 1; i < month; i++) {
            timestamp += DAY_IN_SECONDS * monthDayCounts[i - 1];
        }

        // Day
        timestamp += DAY_IN_SECONDS * (day - 1);

        // Hour
        timestamp += HOUR_IN_SECONDS * (hour);

        // Minute
        timestamp += MINUTE_IN_SECONDS * (minute);

        // Second
        timestamp += second;

        return timestamp;
    }
}

// File: contracts/TokenSale.sol



// SPDX-License-Identifier: UNLICENSED
pragma solidity ^0.8.9;

import "@openzeppelin/contracts/access/Ownable.sol";
import "@openzeppelin/contracts/utils/math/SafeMath.sol";
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
import "./Library/DateTime.sol";

contract TokenSale is Ownable, DateTime {
    using SafeMath for uint256;
    using SafeERC20 for IERC20;

    IERC20 public BITFtoken; // BITF Token
    IERC20 public USDToken; // Tether USDT

    uint8 public constant PRESALE_PRICE = 1; // 0.01 USDT for presale
    uint8 public constant PRIVATE_SALE1_PRICE = 3; // 0.03 USDT for private sale#1
    uint8 public constant PRIVATE_SALE2_PRICE = 5; // 0.05 USDT for private sale#2
    uint8 public constant PUBLIC_SALE_PRICE = 7; // 0.07 USDT for public sale
    uint8 public constant PRIVATE_SALE_UNLOCK_PERCENTAGE = 12; // 15% unlocked per month in private sale#1,#2
    uint8 public constant PRESALE_BENIFIT_PERCENTAGE = 25; // 25% of Net Profit Sharing in presale
    uint8 public constant PRIVATE_SALE1_BENIFIT_PERCENTAGE = 20; // 20% of Net Profit Sharing in private sale#1
    uint8 public constant PRIVATE_SALE2_BENIFIT_PERCENTAGE = 15; // 15% of Net Profit Sharing in private sale#2
    uint8 public constant PUBLIC_SALE_BENIFIT_PERCENTAGE = 10; // 10% of Net Profit Sharing in public sale
    uint256 public constant PRESALE_MAX_USDT = 1500 * 10 ** 18; // Max contribution for presale - 1500 USDT
    uint256 public constant PUBLIC_SALE_MAX_USDT = 750 * 10 ** 18; // Max contribution for public sale - 750 USDT
    uint256 public constant PRIVATE_SALE1_MAX_USDT = 200000 * 10 ** 18; // Max contribution for private sale#1 - 200000 USDT
    uint256 public constant PRIVATE_SALE2_MAX_USDT = 350000 * 10 ** 18; // Max contribution for private sale#2 - 350000 USDT
    uint256 public constant PRESALE_DURATION = 2 * 30 days; // 2 months
    uint256 public constant PRIVATE_SALE1_DURATION = 2 * 30 days; // 2 months
    uint256 public constant PRIVATE_SALE2_DURATION = 1 * 30 days; // 1 month
    uint256 public constant PRESALE_LOCK_DURATION = 6 * 30 days; // 6 months
    uint256 public constant PRIVATE_SALE_LOCK_DURATION = 9 * 30 days; // 9 months
    uint256 public constant PRESALE_AMOUNT = 60000000 * 10 ** 18; // PRE SALE Token amount
    uint256 public constant PRIVATE_SALE1_AMOUNT = 80000000 * 10 ** 18; // Private Sale#1 Token amount
    uint256 public constant PRIVATE_SALE2_AMOUNT = 100000000 * 10 ** 18; // Public Sale#2 Token amount
    uint256 public constant PUBLIC_SALE_AMOUNT = 10000000 * 10 ** 18; // Public Sale Token amount

    uint256 public presaleStartTime;
    uint256 public privateSale1StartTime;
    uint256 public privateSale2StartTime;
    uint256 public publicSaleStartTime;
    uint256 public releaseTime;
    uint256 public profitReleaseTime;
    uint256 public presaleSold;
    uint256 public privateSale1Sold;
    uint256 public privateSale2Sold;
    uint256 public publicSaleSold;

    mapping(address => uint256) public presaleBalances;
    mapping(address => uint256) public privateSale1Balances;
    mapping(address => uint256) public privateSale2Balances;
    mapping(address => uint256) public publicSaleBalances;
    mapping(address => uint256) public privateSale1Claimed;
    mapping(address => uint256) public privateSale2Claimed;

    event PreSalePurchased(
        address indexed buyer,
        uint256 USDTamount,
        uint256 BITFamount
    );
    event PrivateSale1Purchased(
        address indexed buyer,
        uint256 USDTamount,
        uint256 BITFamount
    );
    event PrivateSale2Purchased(
        address indexed buyer,
        uint256 USDTamount,
        uint256 BITFamount
    );
    event PublicSalePurchased(
        address indexed buyer,
        uint256 USDTamount,
        uint256 BITFamount
    );

    event ClaimPresale(address indexed claimant, uint256 amount);
    event ClaimPrivateSale1(address indexed claimant, uint256 amount);
    event ClaimPrivateSale2(address indexed claimant, uint256 amount);
    event ClaimPublicSale(address indexed claimant, uint256 amount);

    /**
     @notice contructor of Token Sale, 
     @param _usdToken USDT Token contract address
     */
    constructor(address _usdToken) {
        require(_usdToken != address(0), "Invalid USDT token address");
        USDToken = IERC20(_usdToken);
    }

    /**
     @notice Set BITF Token contract address
     @dev Only Owner is accessible
     @param _bitfToken BITF Token contract address
     */
    function setToken(address _bitfToken) external onlyOwner {
        require(_bitfToken != address(0), "Invalid token address");
        BITFtoken = IERC20(_bitfToken);
    }

    /**
     @notice Set Pre Sale Start Time
     @dev Only Owner is accessible
     @param _year PRE SALE START Year
     @param _month PRESALE START Month
     @param _day PRE SALE START DAY
     */
    function setPresaleStartTime(
        uint16 _year,
        uint8 _month,
        uint8 _day
    ) external onlyOwner {
        uint256 _presaleStartTime = toTimestamp(_year, _month, _day);
        require(
            _presaleStartTime > block.timestamp,
            "Invalid presale start time"
        );
        presaleStartTime = _presaleStartTime;
    }

    function setPrivateSale1StartTime(
        uint16 _year,
        uint8 _month,
        uint8 _day
    ) external onlyOwner {
        uint256 _privatesale1StartTime = toTimestamp(_year, _month, _day);
        require(
            _privatesale1StartTime > block.timestamp &&
                _privatesale1StartTime >= presaleStartTime + PRESALE_DURATION,
            "Invalid private sale#1 start time"
        );
        privateSale1StartTime = _privatesale1StartTime;
    }

    function setPrivateSale2StartTime(
        uint16 _year,
        uint8 _month,
        uint8 _day
    ) external onlyOwner {
        uint256 _privatesale2StartTime = toTimestamp(_year, _month, _day);
        require(
            _privatesale2StartTime > block.timestamp &&
                _privatesale2StartTime >=
                privateSale1StartTime + PRIVATE_SALE1_DURATION,
            "Invalid private sale#2 start time"
        );
        privateSale2StartTime = _privatesale2StartTime;
    }

    function setPublicSaleStartTime(
        uint16 _year,
        uint8 _month,
        uint8 _day
    ) external onlyOwner {
        uint256 _publicSaleStartTime = toTimestamp(_year, _month, _day);
        require(
            _publicSaleStartTime > block.timestamp &&
                _publicSaleStartTime >=
                privateSale1StartTime + PRIVATE_SALE2_DURATION,
            "Invalid public sale start time"
        );
        publicSaleStartTime = _publicSaleStartTime;
    }

    /**
     @notice Set Release Time. Time Stamp Start date for Token release Jun 21 2024
     @dev OnlyOwner is accessible
     */
    function setReleaseTime(
        uint16 _year,
        uint8 _month,
        uint8 _day
    ) external onlyOwner {
        releaseTime = toTimestamp(_year, _month, _day);
    }

    /**
     @notice Set Profit Release Time. Time Stamp Start date for Token release August 21 2024
     @dev OnlyOwner is accessible
     */
    function setProfitReleaseTime(
        uint16 _year,
        uint8 _month,
        uint8 _day
    ) external onlyOwner {
        profitReleaseTime = toTimestamp(_year, _month, _day);
    }

    /**
     @notice Buy BITF tokens in Presale & Private Sale #1 & Private Sale #2 & Public Sale
     @dev After presale starts, this function would be available.
     @param _amount BITF token amount to buy
     */
    function buyBitfinder(uint256 _amount) external {
        uint256 currentTime = block.timestamp;
        uint256 poolBalance = BITFtoken.balanceOf(address(this));
        uint256 usdtamount;
        require(currentTime >= presaleStartTime, "Presale has not started yet");
        require(_amount > 0, "Amount must be greater than zero");
        require(_amount <= poolBalance, "Buy token amount is exceeded");
        if (currentTime <= presaleStartTime + PRESALE_DURATION) {
            require(
                presaleSold + _amount <= PRESALE_AMOUNT,
                "Presale Cap reached"
            );
            uint256 _balance;
            _balance = presaleBalances[_msgSender()];
            require(
                ((_balance + _amount) * PRESALE_PRICE) / 100 <=
                    PRESALE_MAX_USDT,
                "Reached to Max Token contribuiton of Presale"
            );
            usdtamount = (_amount * PRESALE_PRICE) / 100;
            USDToken.safeTransferFrom(_msgSender(), address(this), usdtamount);
            presaleBalances[_msgSender()] += _amount;
            presaleSold += _amount;
            emit PreSalePurchased(_msgSender(), usdtamount, _amount);
        } else if (
            currentTime >= privateSale1StartTime &&
            currentTime <= privateSale1StartTime + PRIVATE_SALE1_DURATION
        ) {
            require(
                privateSale1Sold + _amount <= PRIVATE_SALE1_AMOUNT,
                "Private sale#1 Cap reached"
            );
            uint256 _balance;
            _balance = privateSale1Balances[_msgSender()];
            require(
                ((_balance + _amount) * PRIVATE_SALE1_PRICE) / 100 <=
                    PRIVATE_SALE1_MAX_USDT,
                "Reached to Max Token contribuiton of Private sale#1"
            );
            usdtamount = (_amount * PRIVATE_SALE1_PRICE) / 100;
            USDToken.safeTransferFrom(_msgSender(), address(this), usdtamount);
            privateSale1Balances[_msgSender()] += _amount;
            privateSale1Sold += _amount;
            emit PrivateSale1Purchased(_msgSender(), usdtamount, _amount);
        } else if (
            currentTime >= privateSale2StartTime &&
            currentTime <= privateSale2StartTime + PRIVATE_SALE2_DURATION
        ) {
            require(
                privateSale2Sold + _amount <= PRIVATE_SALE2_AMOUNT,
                "Private sale#2 Cap reached"
            );
            uint256 _balance;
            _balance = privateSale2Balances[_msgSender()];
            require(
                ((_balance + _amount) * PRIVATE_SALE2_PRICE) / 100 <=
                    PRIVATE_SALE2_MAX_USDT,
                "Reached to Max Token contribuiton of Private sale#2"
            );
            usdtamount = (_amount * PRIVATE_SALE2_PRICE) / 100;
            USDToken.safeTransferFrom(_msgSender(), address(this), usdtamount);
            privateSale2Balances[_msgSender()] += _amount;
            privateSale2Sold += _amount;
            emit PrivateSale2Purchased(_msgSender(), usdtamount, _amount);
        } else if (currentTime >= publicSaleStartTime) {
            require(
                publicSaleSold + _amount <= PUBLIC_SALE_AMOUNT,
                "Public sale Cap reached"
            );
            uint256 _balance;
            _balance = publicSaleBalances[_msgSender()];
            require(
                ((_balance + _amount) * PUBLIC_SALE_PRICE) / 100 <=
                    PUBLIC_SALE_MAX_USDT,
                "Reached to Max Token contribuiton of Public sale"
            );
            usdtamount = (_amount * PUBLIC_SALE_PRICE) / 100;
            USDToken.safeTransferFrom(_msgSender(), address(this), usdtamount);
            publicSaleBalances[_msgSender()] += _amount;
            publicSaleSold += _amount;
            emit PublicSalePurchased(_msgSender(), usdtamount, _amount);
        }
    }

    function claimPresaleToken(uint256 _amount) external {
        require(
            block.timestamp >= releaseTime,
            "Token is not available to release yet"
        );
        require(
            presaleBalances[_msgSender()] >= _amount,
            "Claim amount exceeds balance"
        );
        BITFtoken.safeTransfer(_msgSender(), _amount);
        presaleBalances[_msgSender()] -= _amount;
        emit ClaimPresale(_msgSender(), _amount);
    }

    function claimPrivateSale1Token(uint256 _amount) external {
        require(
            block.timestamp >= releaseTime,
            "Token is not available to release yet"
        );
        uint256 initialBalance = privateSale1Balances[_msgSender()] +
            privateSale1Claimed[_msgSender()];
        require(
            getPrivateSaleClaimAmount(initialBalance) >=
                _amount + privateSale1Claimed[_msgSender()],
            "Claim amount exceeds Available Amount"
        );
        BITFtoken.safeTransfer(_msgSender(), _amount);
        privateSale1Balances[_msgSender()] -= _amount;
        privateSale1Claimed[_msgSender()] += _amount;
        emit ClaimPrivateSale1(_msgSender(), _amount);
    }

    function claimPrivateSale2Token(uint256 _amount) external {
        require(
            block.timestamp >= releaseTime,
            "Token is not available to release yet"
        );
        uint256 initialBalance = privateSale2Balances[_msgSender()] +
            privateSale2Claimed[_msgSender()];
        require(
            getPrivateSaleClaimAmount(initialBalance) >=
                _amount + privateSale2Claimed[_msgSender()],
            "Claim amount exceeds Available Amount"
        );
        BITFtoken.safeTransfer(_msgSender(), _amount);
        privateSale2Balances[_msgSender()] -= _amount;
        privateSale2Claimed[_msgSender()] += _amount;
        emit ClaimPrivateSale2(_msgSender(), _amount);
    }

    function claimPublicSaleToken(uint256 _amount) external {
        require(
            block.timestamp >= releaseTime,
            "Token is not available to release yet"
        );
        require(
            publicSaleBalances[_msgSender()] >= _amount,
            "Claim amount exceeds balance"
        );
        BITFtoken.safeTransfer(_msgSender(), _amount);
        publicSaleBalances[_msgSender()] -= _amount;
        emit ClaimPublicSale(_msgSender(), _amount);
    }

    function getPrivateSaleClaimAmount(
        uint256 balance
    ) public view returns (uint256) {
        uint256 currentTimeStamp = block.timestamp;
        require(currentTimeStamp >= block.timestamp );
        uint16 currentYear = getYear(currentTimeStamp);
        uint8 currentMonth = getMonth(currentTimeStamp);
        uint16 releaseYear = getYear(releaseTime);
        uint8 releaseMonth = getMonth(releaseTime);
        uint256 months = (currentYear - releaseYear) * 12;
        if(releaseMonth > currentMonth) {
            months -= (releaseMonth - currentMonth);
        } else {
            months += (currentMonth - releaseMonth);
        }
        uint256 amount = balance
            .mul(PRIVATE_SALE_UNLOCK_PERCENTAGE)
            .div(100)
            .mul(months);
        if (amount > balance) return balance;
        return amount;
    }

    function withdrawToken() external onlyOwner {
        uint256 balance = BITFtoken.balanceOf(address(this));
        require(balance > 0, "No USDT tokens to withdraw");
        BITFtoken.safeTransfer(owner(), balance);
    }

    function withdrawUSDT() external onlyOwner {
        uint256 balance = USDToken.balanceOf(address(this));
        require(balance > 0, "No tokens to withdraw");
        USDToken.safeTransfer(owner(), balance);
    }
}