// 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/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/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: @chainlink/contracts/src/v0.8/interfaces/AggregatorV3Interface.sol

pragma solidity ^0.8.0;

interface AggregatorV3Interface {
    function decimals() external view returns (uint8);

    function description() external view returns (string memory);

    function version() external view returns (uint256);

    function getRoundData(
        uint80 _roundId
    )
        external
        view
        returns (
            uint80 roundId,
            int256 answer,
            uint256 startedAt,
            uint256 updatedAt,
            uint80 answeredInRound
        );

    function latestRoundData()
        external
        view
        returns (
            uint80 roundId,
            int256 answer,
            uint256 startedAt,
            uint256 updatedAt,
            uint80 answeredInRound
        );
}

// File: contracts/Itoken.sol

pragma solidity ^0.8.4;

interface iTokenContract {
    event tokenStake(
        uint indexed id,
        address indexed staker,
        uint indexed tokenAmount
    );
    event releaseStake(
        uint indexed id,
        address indexed staker,
        uint indexed tokenAmount
    );

    function stake(address _staker, uint256 _amount) external returns (bool);
}

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;

    /**
     * @dev Unauthorized reentrant call.
     */
    error ReentrancyGuardReentrantCall();

    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
        if (_status == ENTERED) {
            revert ReentrancyGuardReentrantCall();
        }

        // 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;
    }
}

interface IERC165 {
    /**
     * @dev Returns true if this contract implements the interface defined by
     * `interfaceId`. See the corresponding
     * https://eips.ethereum.org/EIPS/eip-165#how-interfaces-are-identified[ERC section]
     * to learn more about how these ids are created.
     *
     * This function call must use less than 30 000 gas.
     */
    function supportsInterface(bytes4 interfaceId) external view returns (bool);
}

pragma solidity ^0.8.20;

interface IERC1363 is IERC20, IERC165 {
    /*
     * Note: the ERC-165 identifier for this interface is 0xb0202a11.
     * 0xb0202a11 ===
     *   bytes4(keccak256('transferAndCall(address,uint256)')) ^
     *   bytes4(keccak256('transferAndCall(address,uint256,bytes)')) ^
     *   bytes4(keccak256('transferFromAndCall(address,address,uint256)')) ^
     *   bytes4(keccak256('transferFromAndCall(address,address,uint256,bytes)')) ^
     *   bytes4(keccak256('approveAndCall(address,uint256)')) ^
     *   bytes4(keccak256('approveAndCall(address,uint256,bytes)'))
     */

    /**
     * @dev Moves a `value` amount of tokens from the caller's account to `to`
     * and then calls {IERC1363Receiver-onTransferReceived} on `to`.
     * @param to The address which you want to transfer to.
     * @param value The amount of tokens to be transferred.
     * @return A boolean value indicating whether the operation succeeded unless throwing.
     */
    function transferAndCall(address to, uint256 value) external returns (bool);

    /**
     * @dev Moves a `value` amount of tokens from the caller's account to `to`
     * and then calls {IERC1363Receiver-onTransferReceived} on `to`.
     * @param to The address which you want to transfer to.
     * @param value The amount of tokens to be transferred.
     * @param data Additional data with no specified format, sent in call to `to`.
     * @return A boolean value indicating whether the operation succeeded unless throwing.
     */
    function transferAndCall(
        address to,
        uint256 value,
        bytes calldata data
    ) external returns (bool);

    /**
     * @dev Moves a `value` amount of tokens from `from` to `to` using the allowance mechanism
     * and then calls {IERC1363Receiver-onTransferReceived} on `to`.
     * @param from The address which you want to send tokens from.
     * @param to The address which you want to transfer to.
     * @param value The amount of tokens to be transferred.
     * @return A boolean value indicating whether the operation succeeded unless throwing.
     */
    function transferFromAndCall(
        address from,
        address to,
        uint256 value
    ) external returns (bool);

    /**
     * @dev Moves a `value` amount of tokens from `from` to `to` using the allowance mechanism
     * and then calls {IERC1363Receiver-onTransferReceived} on `to`.
     * @param from The address which you want to send tokens from.
     * @param to The address which you want to transfer to.
     * @param value The amount of tokens to be transferred.
     * @param data Additional data with no specified format, sent in call to `to`.
     * @return A boolean value indicating whether the operation succeeded unless throwing.
     */
    function transferFromAndCall(
        address from,
        address to,
        uint256 value,
        bytes calldata data
    ) external returns (bool);

    /**
     * @dev Sets a `value` amount of tokens as the allowance of `spender` over the
     * caller's tokens and then calls {IERC1363Spender-onApprovalReceived} on `spender`.
     * @param spender The address which will spend the funds.
     * @param value The amount of tokens to be spent.
     * @return A boolean value indicating whether the operation succeeded unless throwing.
     */
    function approveAndCall(
        address spender,
        uint256 value
    ) external returns (bool);

    /**
     * @dev Sets a `value` amount of tokens as the allowance of `spender` over the
     * caller's tokens and then calls {IERC1363Spender-onApprovalReceived} on `spender`.
     * @param spender The address which will spend the funds.
     * @param value The amount of tokens to be spent.
     * @param data Additional data with no specified format, sent in call to `spender`.
     * @return A boolean value indicating whether the operation succeeded unless throwing.
     */
    function approveAndCall(
        address spender,
        uint256 value,
        bytes calldata data
    ) external returns (bool);
}

/**
 * @title SafeERC20
 * @dev Wrappers around ERC-20 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 {
    /**
     * @dev An operation with an ERC-20 token failed.
     */
    error SafeERC20FailedOperation(address token);

    /**
     * @dev Indicates a failed `decreaseAllowance` request.
     */
    error SafeERC20FailedDecreaseAllowance(
        address spender,
        uint256 currentAllowance,
        uint256 requestedDecrease
    );

    /**
     * @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.encodeCall(token.transfer, (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.encodeCall(token.transferFrom, (from, to, 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.
     *
     * IMPORTANT: If the token implements ERC-7674 (ERC-20 with temporary allowance), and if the "client"
     * smart contract uses ERC-7674 to set temporary allowances, then the "client" smart contract should avoid using
     * this function. Performing a {safeIncreaseAllowance} or {safeDecreaseAllowance} operation on a token contract
     * that has a non-zero temporary allowance (for that particular owner-spender) will result in unexpected behavior.
     */
    function safeIncreaseAllowance(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        uint256 oldAllowance = token.allowance(address(this), spender);
        forceApprove(token, spender, oldAllowance + value);
    }

    /**
     * @dev Decrease the calling contract's allowance toward `spender` by `requestedDecrease`. If `token` returns no
     * value, non-reverting calls are assumed to be successful.
     *
     * IMPORTANT: If the token implements ERC-7674 (ERC-20 with temporary allowance), and if the "client"
     * smart contract uses ERC-7674 to set temporary allowances, then the "client" smart contract should avoid using
     * this function. Performing a {safeIncreaseAllowance} or {safeDecreaseAllowance} operation on a token contract
     * that has a non-zero temporary allowance (for that particular owner-spender) will result in unexpected behavior.
     */
    function safeDecreaseAllowance(
        IERC20 token,
        address spender,
        uint256 requestedDecrease
    ) internal {
        unchecked {
            uint256 currentAllowance = token.allowance(address(this), spender);
            if (currentAllowance < requestedDecrease) {
                revert SafeERC20FailedDecreaseAllowance(
                    spender,
                    currentAllowance,
                    requestedDecrease
                );
            }
            forceApprove(token, spender, currentAllowance - requestedDecrease);
        }
    }

    /**
     * @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.
     *
     * NOTE: If the token implements ERC-7674, this function will not modify any temporary allowance. This function
     * only sets the "standard" allowance. Any temporary allowance will remain active, in addition to the value being
     * set here.
     */
    function forceApprove(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        bytes memory approvalCall = abi.encodeCall(
            token.approve,
            (spender, value)
        );

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

    /**
     * @dev Performs an {ERC1363} transferAndCall, with a fallback to the simple {ERC20} transfer if the target has no
     * code. This can be used to implement an {ERC721}-like safe transfer that rely on {ERC1363} checks when
     * targeting contracts.
     *
     * Reverts if the returned value is other than `true`.
     */
    function transferAndCallRelaxed(
        IERC1363 token,
        address to,
        uint256 value,
        bytes memory data
    ) internal {
        if (to.code.length == 0) {
            safeTransfer(token, to, value);
        } else if (!token.transferAndCall(to, value, data)) {
            revert SafeERC20FailedOperation(address(token));
        }
    }

    /**
     * @dev Performs an {ERC1363} transferFromAndCall, with a fallback to the simple {ERC20} transferFrom if the target
     * has no code. This can be used to implement an {ERC721}-like safe transfer that rely on {ERC1363} checks when
     * targeting contracts.
     *
     * Reverts if the returned value is other than `true`.
     */
    function transferFromAndCallRelaxed(
        IERC1363 token,
        address from,
        address to,
        uint256 value,
        bytes memory data
    ) internal {
        if (to.code.length == 0) {
            safeTransferFrom(token, from, to, value);
        } else if (!token.transferFromAndCall(from, to, value, data)) {
            revert SafeERC20FailedOperation(address(token));
        }
    }

    /**
     * @dev Performs an {ERC1363} approveAndCall, with a fallback to the simple {ERC20} approve if the target has no
     * code. This can be used to implement an {ERC721}-like safe transfer that rely on {ERC1363} checks when
     * targeting contracts.
     *
     * NOTE: When the recipient address (`to`) has no code (i.e. is an EOA), this function behaves as {forceApprove}.
     * Opposedly, when the recipient address (`to`) has code, this function only attempts to call {ERC1363-approveAndCall}
     * once without retrying, and relies on the returned value to be true.
     *
     * Reverts if the returned value is other than `true`.
     */
    function approveAndCallRelaxed(
        IERC1363 token,
        address to,
        uint256 value,
        bytes memory data
    ) internal {
        if (to.code.length == 0) {
            forceApprove(token, to, value);
        } else if (!token.approveAndCall(to, value, data)) {
            revert SafeERC20FailedOperation(address(token));
        }
    }

    /**
     * @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 {_callOptionalReturnBool} that reverts if call fails to meet the requirements.
     */
    function _callOptionalReturn(IERC20 token, bytes memory data) private {
        uint256 returnSize;
        uint256 returnValue;
        assembly ("memory-safe") {
            let success := call(
                gas(),
                token,
                0,
                add(data, 0x20),
                mload(data),
                0,
                0x20
            )
            // bubble errors
            if iszero(success) {
                let ptr := mload(0x40)
                returndatacopy(ptr, 0, returndatasize())
                revert(ptr, returndatasize())
            }
            returnSize := returndatasize()
            returnValue := mload(0)
        }

        if (
            returnSize == 0 ? address(token).code.length == 0 : returnValue != 1
        ) {
            revert SafeERC20FailedOperation(address(token));
        }
    }

    /**
     * @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 silently catches all reverts and returns a bool instead.
     */
    function _callOptionalReturnBool(
        IERC20 token,
        bytes memory data
    ) private returns (bool) {
        bool success;
        uint256 returnSize;
        uint256 returnValue;
        assembly ("memory-safe") {
            success := call(
                gas(),
                token,
                0,
                add(data, 0x20),
                mload(data),
                0,
                0x20
            )
            returnSize := returndatasize()
            returnValue := mload(0)
        }
        return
            success &&
            (
                returnSize == 0
                    ? address(token).code.length > 0
                    : returnValue == 1
            );
    }
}

interface IERC20Metadata is IERC20 {
    /**
     * @dev Returns the name of the token.
     */
    function name() external view returns (string memory);

    /**
     * @dev Returns the symbol of the token.
     */
    function symbol() external view returns (string memory);

    /**
     * @dev Returns the decimals places of the token.
     */
    function decimals() external view returns (uint8);
}


pragma solidity ^0.8.4;
contract GOIL_Vendor is Ownable, ReentrancyGuard {
    using SafeERC20 for IERC20Metadata;

    uint maxBuy = 82712985;
    uint public currentRoundIndex = 0;
    bool public passRound = true;

    address public tokenAddress;
    address public priceAddress;
    address public usdtAddress;

    struct Round {
        uint64 roundAmount;
        // price in usdt
        uint64 roundPrice;
    }

    Round[] public rounds;
    bool public isSaleOpen = true;
    AggregatorV3Interface ethInUsdDataFeed;

    IERC20Metadata tokenInterface;
    IERC20Metadata usdtInterface;

    event BuyTokens(address buyer, uint256 amountOfETH, uint256 amountOfTokens);
    event BuyTokensUSDT(
        address buyer,
        uint256 amountOfUSDT,
        uint256 amountOfTokens
    );

    constructor(
        address _tokenAddress,
        address _priceAddress,
        address _usdtAddress
    ) {
        tokenAddress = _tokenAddress;
        priceAddress = _priceAddress;
        usdtAddress = _usdtAddress;
        ethInUsdDataFeed = AggregatorV3Interface(priceAddress);
        tokenInterface = IERC20Metadata(_tokenAddress);
        usdtInterface = IERC20Metadata(_usdtAddress);

        addRound(1_000_000_000, 60_400);
        addRound(1_000_000_000, 120_900);
        addRound(1_000_000_000, 211_500);
        addRound(1_000_000_000, 317_402);
    }

    function transferTokens(
        address _to,
        uint256 _amount
    ) private returns (uint256) {
        uint256 amountToTransfer = _amount * 10 ** tokenInterface.decimals();
        require(
            tokenInterface.balanceOf(address(this)) >= amountToTransfer,
            "Insufficient tokens in contract"
        );
        require(
            tokenInterface.transfer(_to, amountToTransfer),
            "Token transfer failed"
        );
        return amountToTransfer;
    }

    function getUsdtPrice(uint _tokenAmount) public view returns (uint) {
        uint tokenPrice = getTokenPriceInUSD(); // Token price in USD with 8 decimals
        uint8 usdtDecimals = usdtInterface.decimals();
        // Calculate USDT amount in smallest units
        uint usdtTokenVal = (_tokenAmount * tokenPrice * 10 ** usdtDecimals) /
            10 ** 8;

        return usdtTokenVal;
    }

    function getCurrentRoundData()
        external
        view
        returns (uint roundAmount, uint roundPrice, uint roundIndex)
    {
        require(
            currentRoundIndex < rounds.length,
            "Current round index out of bounds"
        );
        Round memory currentRound = rounds[currentRoundIndex];
        return (
            currentRound.roundAmount,
            currentRound.roundPrice,
            currentRoundIndex
        );
    }

    function isAllowedToBuy(uint64 _amount) private view returns (bool) {
        require(isSaleOpen, "sale closed");
        uint currentRoundAmount = rounds[currentRoundIndex].roundAmount;
        require(
            _amount > 0 && currentRoundAmount >= _amount,
            "exceeds round limit"
        );
        require(_amount <= maxBuy, "exceeds max buy");
        return true;
    }

    /**
     * @return price Price for 1 integer token in USD with 8 decimals
     */
    function getTokenPriceInUSD() public view returns (uint price) {
        require(isSaleOpen, "sale closed");
        require(
            currentRoundIndex < rounds.length,
            "Current round index out of bounds"
        );
        uint currentPrice = rounds[currentRoundIndex].roundPrice;
        return currentPrice;
    }

    function buyTokenErc20(
        uint64 _amount
    ) external nonReentrant returns (bool) {
        require(_amount > 0, "Amount must be greater than 0");
        require(isAllowedToBuy(_amount), "Purchase not confirmed");

        uint usdtTokenVal = getUsdtPrice(_amount);
        require(usdtTokenVal > 0, "USDT amount is zero");

        require(
            usdtInterface.allowance(msg.sender, address(this)) >= usdtTokenVal,
            "USDT allowance not enough"
        );

        rounds[currentRoundIndex].roundAmount -= _amount;

        if (
            passRound &&
            rounds[currentRoundIndex].roundAmount == 0 &&
            currentRoundIndex < rounds.length - 1
        ) {
            currentRoundIndex++;
        }

        // Transfer USDT from buyer to vendor

        usdtInterface.safeTransferFrom(msg.sender, address(this), usdtTokenVal);

        uint256 tokensTransfered = transferTokens(msg.sender, _amount);

        emit BuyTokensUSDT(msg.sender, usdtTokenVal, tokensTransfered);
        return true;
    }

    /**
     * @param _amount integer amount of tokens, not taking into account token decimals
     */
    function buyEthTokens(
        uint64 _amount
    ) public payable nonReentrant returns (bool) {
        require(_amount > 0, "Amount must be greater than 0");
        require(isAllowedToBuy(_amount));
        uint256 weiTokenVal = getWeiPrice(_amount);
        require(msg.value >= weiTokenVal, "insufficient ETH");

        rounds[currentRoundIndex].roundAmount -= _amount;

        if (
            passRound &&
            rounds[currentRoundIndex].roundAmount == 0 &&
            currentRoundIndex < rounds.length - 1
        ) {
            currentRoundIndex++;
        }

        uint256 amountTransfered = transferTokens(msg.sender, _amount);

        emit BuyTokens(msg.sender, msg.value, amountTransfered);
        return true;
    }

    function getWeiPrice(uint _amount) public view returns (uint) {
        (, int256 ethUsd, , , ) = ethInUsdDataFeed.latestRoundData();
        require(ethUsd > 0, "Invalid price from data feed");
        uint tokensPriceInUsd = _amount * getTokenPriceInUSD();
        uint weiTokenVal = (1 ether * tokensPriceInUsd) / uint256(ethUsd);

        return weiTokenVal;
    }

    function withdrawUsdt(uint256 _amount) external onlyOwner {
        usdtInterface.safeTransfer(owner(), _amount);
    }

    function withdraw() public onlyOwner {
        uint256 contractBalance = address(this).balance;
        require(contractBalance > 0, "Contract has no balance to withdraw");

        payable(owner()).transfer(address(this).balance);
    }

    /**
     *  @param _roundAmount integer amount of tokens in round, not taking into account token decimals
     *  @param _roundPrice price per 1 integer token in USD with 8 decimals
     */
    function addRound(
        uint64 _roundAmount,
        uint64 _roundPrice
    ) public onlyOwner {
        rounds.push(Round(_roundAmount, _roundPrice));
    }

    /**
     *  @param index id of the round
     *  @param _roundAmount integer amount of tokens in round, not taking into account token decimals
     *  @param _roundPrice price per 1 integer token in USD with 8 decimals
     */
    function updateRound(
        uint index,
        uint64 _roundAmount,
        uint64 _roundPrice
    ) external onlyOwner {
        require(index < rounds.length, "Round index out of bounds");
        rounds[index] = Round(_roundAmount, _roundPrice);
    }

    function updateCurrentRoundIndex(uint newIndex) external onlyOwner {
        require(newIndex < rounds.length, "Index out of bounds");
        currentRoundIndex = newIndex;
    }

    function updateMaxBuy(uint _max) external onlyOwner {
        maxBuy = _max;
    }

    function updateSaleStatus(bool _isSaleOpen) external onlyOwner {
        isSaleOpen = _isSaleOpen;
    }

    function updatePassRound(bool _isPassRound) external onlyOwner {
        passRound = _isPassRound;
    }

    function updateTokenAddress(address _address) external onlyOwner {
        tokenInterface = IERC20Metadata(_address);
    }
}

{
  "compilationTarget": {
    "vendor.sol": "GOIL_Vendor"
  },
  "evmVersion": "cancun",
  "libraries": {},
  "metadata": {
    "bytecodeHash": "ipfs"
  },
  "optimizer": {
    "enabled": false,
    "runs": 200
  },
  "remappings": []
}