pragma solidity 0.6.12;
pragma experimental ABIEncoderV2;

/**
 * @dev Wrappers over Solidity's arithmetic operations with added overflow
 * checks.
 *
 * Arithmetic operations in Solidity wrap on overflow. This can easily result
 * in bugs, because programmers usually assume that an overflow raises an
 * error, which is the standard behavior in high level programming languages.
 * `SafeMath` restores this intuition by reverting the transaction when an
 * operation overflows.
 *
 * Using this library instead of the unchecked operations eliminates an entire
 * class of bugs, so it's recommended to use it always.
 */
library SafeMath {
    /**
     * @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) {
        uint256 c = a + b;
        require(c >= a, "SafeMath: addition overflow");

        return c;
    }

    /**
     * @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 sub(a, b, "SafeMath: subtraction overflow");
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b <= a, errorMessage);
        uint256 c = a - b;

        return c;
    }

    /**
     * @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) {
        // 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 0;
        }

        uint256 c = a * b;
        require(c / a == b, "SafeMath: multiplication overflow");

        return c;
    }

    /**
     * @dev Returns the integer division of two unsigned integers. Reverts 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) internal pure returns (uint256) {
        return div(a, b, "SafeMath: division by zero");
    }

    /**
     * @dev Returns the integer division of two unsigned integers. Reverts 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) {
        require(b > 0, errorMessage);
        uint256 c = a / b;
        // assert(a == b * c + a % b); // There is no case in which this doesn't hold

        return c;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts 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 mod(a, b, "SafeMath: modulo by zero");
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts with custom message 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, string memory errorMessage) internal pure returns (uint256) {
        require(b != 0, errorMessage);
        return a % b;
    }
}

/*
 * @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 GSN 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 payable) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes memory) {
        this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
        return msg.data;
    }
}

/**
 * @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.
 */
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 () internal {
        address msgSender = _msgSender();
        _owner = msgSender;
        emit OwnershipTransferred(address(0), msgSender);
    }

    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        require(_owner == _msgSender(), "Ownable: caller is not the owner");
        _;
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions anymore. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby removing any functionality that is only available to the owner.
     */
    function renounceOwnership() public virtual onlyOwner {
        emit OwnershipTransferred(_owner, address(0));
        _owner = 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");
        emit OwnershipTransferred(_owner, newOwner);
        _owner = newOwner;
    }
}

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @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 `recipient`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address recipient, 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 `sender` to `recipient` 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 sender, address recipient, uint256 amount) external returns (bool);

    /**
     * @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 Implementation of the {IERC20} interface.
 *
 * This implementation is agnostic to the way tokens are created. This means
 * that a supply mechanism has to be added in a derived contract using {_mint}.
 * For a generic mechanism see {ERC20PresetMinterPauser}.
 *
 * TIP: For a detailed writeup see our guide
 * https://forum.zeppelin.solutions/t/how-to-implement-erc20-supply-mechanisms/226[How
 * to implement supply mechanisms].
 *
 * We have followed general OpenZeppelin guidelines: functions revert instead
 * of returning `false` on failure. This behavior is nonetheless conventional
 * and does not conflict with the expectations of ERC20 applications.
 *
 * Additionally, an {Approval} event is emitted on calls to {transferFrom}.
 * This allows applications to reconstruct the allowance for all accounts just
 * by listening to said events. Other implementations of the EIP may not emit
 * these events, as it isn't required by the specification.
 *
 * Finally, the non-standard {decreaseAllowance} and {increaseAllowance}
 * functions have been added to mitigate the well-known issues around setting
 * allowances. See {IERC20-approve}.
 */
abstract contract ERC20 is Context, IERC20 {
    
    using SafeMath for uint256;

    mapping (address => uint256) private _balances;

    mapping (address => mapping (address => uint256)) private _allowances;

    uint256 private _totalSupply;

    string private _name;
    string private _symbol;
    uint8 private _decimals;

    /**
     * @dev Sets the values for {name} and {symbol}, initializes {decimals} with
     * a default value of 18.
     *
     * To select a different value for {decimals}, use {_setupDecimals}.
     *
     * All three of these values are immutable: they can only be set once during
     * construction.
     */
    constructor (string memory name, string memory symbol, uint8 decimals) public {
        _name = name;
        _symbol = symbol;
        _decimals = decimals;
    }

    /**
     * @dev Returns the name of the token.
     */
    function name() public view returns (string memory) {
        return _name;
    }

    /**
     * @dev Returns the symbol of the token, usually a shorter version of the
     * name.
     */
    function symbol() public view returns (string memory) {
        return _symbol;
    }

    /**
     * @dev Returns the number of decimals used to get its user representation.
     * For example, if `decimals` equals `2`, a balance of `505` tokens should
     * be displayed to a user as `5,05` (`505 / 10 ** 2`).
     *
     * Tokens usually opt for a value of 18, imitating the relationship between
     * Ether and Wei. This is the value {ERC20} uses, unless {_setupDecimals} is
     * called.
     *
     * NOTE: This information is only used for _display_ purposes: it in
     * no way affects any of the arithmetic of the contract, including
     * {IERC20-balanceOf} and {IERC20-transfer}.
     */
    function decimals() public view returns (uint8) {
        return _decimals;
    }

    /**
     * @dev See {IERC20-totalSupply}.
     */
    function totalSupply() public view override returns (uint256) {
        return _totalSupply;
    }

    /**
     * @dev See {IERC20-balanceOf}.
     */
    function balanceOf(address account) public view override returns (uint256) {
        return _balances[account];
    }

    /**
     * @dev See {IERC20-transfer}.
     *
     * Requirements:
     *
     * - `recipient` cannot be the zero address.
     * - the caller must have a balance of at least `amount`.
     */
    function transfer(address recipient, uint256 amount) public virtual override returns (bool) {
        _transfer(_msgSender(), recipient, amount);
        return true;
    }

    /**
     * @dev See {IERC20-allowance}.
     */
    function allowance(address owner, address spender) public view virtual override returns (uint256) {
        return _allowances[owner][spender];
    }

    /**
     * @dev See {IERC20-approve}.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function approve(address spender, uint256 amount) public virtual override returns (bool) {
        _approve(_msgSender(), spender, amount);
        return true;
    }

    /**
     * @dev See {IERC20-transferFrom}.
     *
     * Emits an {Approval} event indicating the updated allowance. This is not
     * required by the EIP. See the note at the beginning of {ERC20};
     *
     * Requirements:
     * - `sender` and `recipient` cannot be the zero address.
     * - `sender` must have a balance of at least `amount`.
     * - the caller must have allowance for ``sender``'s tokens of at least
     * `amount`.
     */
    function transferFrom(address sender, address recipient, uint256 amount) public virtual override returns (bool) {
        _transfer(sender, recipient, amount);
        _approve(sender, _msgSender(), _allowances[sender][_msgSender()].sub(amount, "ERC20: transfer amount exceeds allowance"));
        return true;
    }

    /**
     * @dev Atomically increases the allowance granted to `spender` by the caller.
     *
     * This is an alternative to {approve} that can be used as a mitigation for
     * problems described in {IERC20-approve}.
     *
     * Emits an {Approval} event indicating the updated allowance.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function increaseAllowance(address spender, uint256 addedValue) public virtual returns (bool) {
        _approve(_msgSender(), spender, _allowances[_msgSender()][spender].add(addedValue));
        return true;
    }

    /**
     * @dev Atomically decreases the allowance granted to `spender` by the caller.
     *
     * This is an alternative to {approve} that can be used as a mitigation for
     * problems described in {IERC20-approve}.
     *
     * Emits an {Approval} event indicating the updated allowance.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     * - `spender` must have allowance for the caller of at least
     * `subtractedValue`.
     */
    function decreaseAllowance(address spender, uint256 subtractedValue) public virtual returns (bool) {
        _approve(_msgSender(), spender, _allowances[_msgSender()][spender].sub(subtractedValue, "ERC20: decreased allowance below zero"));
        return true;
    }

    /**
     * @dev Moves tokens `amount` from `sender` to `recipient`.
     *
     * This is internal function is equivalent to {transfer}, and can be used to
     * e.g. implement automatic token fees, slashing mechanisms, etc.
     *
     * Emits a {Transfer} event.
     *
     * Requirements:
     *
     * - `sender` cannot be the zero address.
     * - `recipient` cannot be the zero address.
     * - `sender` must have a balance of at least `amount`.
     */
    function _transfer(address sender, address recipient, uint256 amount) internal virtual {
        require(sender != address(0), "ERC20: transfer from the zero address");
        require(recipient != address(0), "ERC20: transfer to the zero address");

        _beforeTokenTransfer(sender, recipient, amount);

        _balances[sender] = _balances[sender].sub(amount, "ERC20: transfer amount exceeds balance");
        _balances[recipient] = _balances[recipient].add(amount);
        emit Transfer(sender, recipient, amount);
    }

    /** @dev Creates `amount` tokens and assigns them to `account`, increasing
     * the total supply.
     *
     * Emits a {Transfer} event with `from` set to the zero address.
     *
     * Requirements
     *
     * - `to` cannot be the zero address.
     */
    function _mint(address account, uint256 amount) internal virtual {
        require(account != address(0), "ERC20: mint to the zero address");

        _beforeTokenTransfer(address(0), account, amount);

        _totalSupply = _totalSupply.add(amount);
        _balances[account] = _balances[account].add(amount);
        emit Transfer(address(0), account, amount);
    }

    /**
     * @dev Destroys `amount` tokens from `account`, reducing the
     * total supply.
     *
     * Emits a {Transfer} event with `to` set to the zero address.
     *
     * Requirements
     *
     * - `account` cannot be the zero address.
     * - `account` must have at least `amount` tokens.
     */
    function _burn(address account, uint256 amount) internal virtual {
        require(account != address(0), "ERC20: burn from the zero address");

        _beforeTokenTransfer(account, address(0), amount);

        _balances[account] = _balances[account].sub(amount, "ERC20: burn amount exceeds balance");
        _totalSupply = _totalSupply.sub(amount);
        emit Transfer(account, address(0), amount);
    }

    /**
     * @dev Sets `amount` as the allowance of `spender` over the `owner` s tokens.
     *
     * This internal function is equivalent to `approve`, and can be used to
     * e.g. set automatic allowances for certain subsystems, etc.
     *
     * Emits an {Approval} event.
     *
     * Requirements:
     *
     * - `owner` cannot be the zero address.
     * - `spender` cannot be the zero address.
     */
    function _approve(address owner, address spender, uint256 amount) internal virtual {
        require(owner != address(0), "ERC20: approve from the zero address");
        require(spender != address(0), "ERC20: approve to the zero address");

        _allowances[owner][spender] = amount;
        emit Approval(owner, spender, amount);
    }

    /**
     * @dev Sets {decimals} to a value other than the default one of 18.
     *
     * WARNING: This function should only be called from the constructor. Most
     * applications that interact with token contracts will not expect
     * {decimals} to ever change, and may work incorrectly if it does.
     */
    function _setupDecimals(uint8 decimals_) internal {
        _decimals = decimals_;
    }

    /**
     * @dev Hook that is called before any transfer of tokens. This includes
     * minting and burning.
     *
     * Calling conditions:
     *
     * - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
     * will be to transferred to `to`.
     * - when `from` is zero, `amount` tokens will be minted for `to`.
     * - when `to` is zero, `amount` of ``from``'s tokens will be burned.
     * - `from` and `to` are never both zero.
     *
     * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
     */
    function _beforeTokenTransfer(address from, address to, uint256 amount) internal virtual { }
}


contract GLG is Ownable, ERC20 {
    
    uint8 constant tokenDecimals = 18;

    mapping(address => bool) public whitelist;
    bool public whitelistEnabled;
    
    
    struct Claim {
        address addr;
        uint256 amount;
    }
    
    Claim public specialTeamClaim = Claim(
        address(0), // update address
        50000000 * 10 ** uint256(tokenDecimals)
    );
    
    Claim public devClaim = Claim(
        address(0), // update address
        300000000 * 10 ** uint256(tokenDecimals)
    );
    
    Claim public teamClaim = Claim(
        address(0), // update address
        150000000 * 10 ** uint256(tokenDecimals)
    );

    Claim public liquidityClaim = Claim(
        address(0), // update address
        300000000 * 10 ** uint256(tokenDecimals)
    );
    
    uint256 public MAX_ETH_PURCHASE = 200 ether;
    
    uint256 public MIN_ETH_PURCHASE = 0.1 ether;
    
    struct Round {
        uint256 price; // price is without token decimals
        uint256 time;
        uint256 tokensAllocated;
    }
    
    Round public round1 = Round(
        95000,  // price is 95000 tokens for 1 ETH
        1608753600, // epoch time max value
        50000000 * 10 ** uint256(tokenDecimals) // tokens for sale in the round
    );
    
    Round public round2 = Round(
        73000,  // price is 73000 tokens for 1 ETH
        1640289600, // epoch time max value
        150000000 * 10 ** uint256(tokenDecimals) // tokens for sale in the round
    );
    
    constructor() public ERC20("Global Lottery Gaming", "GLG", tokenDecimals) {
        _mint(address(this), 800000000 * 10 ** uint256(tokenDecimals));
        whitelistEnabled = true;
    }

    modifier isWhitelisted(address _to) {
        if (whitelistEnabled) {
            require(whitelist[_to], 'not whitelisted');
        }
        _;
    }

    
    function changeSpecialTeamAddress(address newAddr) public onlyOwner {
        require(
            newAddr != address(0),
            "zero address is not allowed"
        );
        
        specialTeamClaim.addr = newAddr;
    }
 
    function changeDevAddress(address newAddr) public onlyOwner {
        require(
            newAddr != address(0),
            "zero address is not allowed"
        );
        
        devClaim.addr = newAddr;
    }   
    
    function changeTeamAddress(address newAddr) public onlyOwner {
        require(
            newAddr != address(0),
            "zero address is not allowed"
        );
        
        teamClaim.addr = newAddr;
    }

    function changeLiquidityAddress(address newAddr) public onlyOwner {
        require(
            newAddr != address(0),
            "zero address is not allowed"
        );
        
        liquidityClaim.addr = newAddr;
    }
    
    function claimTokensBySpecialTeam() public {
        require(
            specialTeamClaim.addr != address(0),
            "address is not set"
        );
        
        require(
            _msgSender() == specialTeamClaim.addr,
            "sender is not valid"
        );
        
        _transfer(address(this), _msgSender(), specialTeamClaim.amount);
        specialTeamClaim.amount = 0;
        
    }
    
    function claimTokensByDev() public {
        require(
            devClaim.addr != address(0),
            "address is not set"
        );
        
        require(
            _msgSender() == devClaim.addr,
            "sender is not valid"
        );
        
        _transfer(address(this), _msgSender(), devClaim.amount);
        devClaim.amount = 0;
    }
    
    function claimTokensByTeam() public {
        require(
            teamClaim.addr != address(0),
            "address is not set"
        );
        
        require(
            _msgSender() == teamClaim.addr,
            "sender is not valid"
        );
        
        _transfer(address(this), _msgSender(), teamClaim.amount);
        teamClaim.amount = 0;
    }

    function claimTokensByLiquidity() public {
        require(
            liquidityClaim.addr != address(0),
            "address is not set"
        );
        
        require(
            _msgSender() == liquidityClaim.addr,
            "sender is not valid"
        );
        
        _transfer(address(this), _msgSender(), liquidityClaim.amount);
        liquidityClaim.amount = 0;
    }
    
    function changeRoundParameters(
        uint256 roundId,
        uint256 price,
        uint256 time
    ) public onlyOwner {
        
        require(
            roundId >= currentRoundId() && roundId <= 2,
            "invalid round id"
        );
        
        Round storage roundToUpdate = round1;
        
        if (roundId == 2) {
            roundToUpdate = round2;
        }
        
        if (price != 0) {
            roundToUpdate.price = price;
        }
        
        if (time != 0) {
            roundToUpdate.time = time;
        }
        
    }
    
    receive() external isWhitelisted(_msgSender()) payable {
        uint256 ETHAmount = msg.value;
        
        require(
            ETHAmount >= MIN_ETH_PURCHASE && ETHAmount <= MAX_ETH_PURCHASE,
            "Ether amount out of range for purchase"
        );
        
        _buyTokens(ETHAmount);
    }

    function transferFund(uint256 amount) external onlyOwner {
        require(address(this).balance >= amount,"not a enough fund");
        _msgSender().transfer(amount);
    }

    
    
    // check current price conversation rule - to be used by DAPP
    function currentTokenPricePerETH() public view returns(uint256) {
        if (
            block.timestamp >= round1.time
            && block.timestamp < round2.time
        ) {
            return round1.price;
        } else if (block.timestamp >= round2.time) {
           return round2.price;
        }
    }
    
    // check current price conversation rule - to be used by DAPP
    function currentRoundId() public view returns(uint256) {
        if (
            block.timestamp >= round1.time
            && block.timestamp < round2.time
        ) {
            return 1;
        }  else if (block.timestamp >= round2.time) {
            return 2;
        }
    }
    

    function switchWhitelistFeature(bool _enabled) public onlyOwner {
        require(whitelistEnabled != _enabled, "same whitelist state already set");
        whitelistEnabled = _enabled;
    }

    function addToWhitelist(address _to) public onlyOwner {
        require(!whitelist[_to], "already whitelisted");
        _setWhitelist(_to, true);
    }

    function removeFromWhitelist(address _to) public onlyOwner {
        require(whitelist[_to], "no need to remove whitelist");
        _setWhitelist(_to, false);
    }

    function addToWhitelistBulk(address[] memory _to) public onlyOwner {
        //be careful with out of gas in a loop
        for (uint i = 0; i < _to.length; i++) {
            _setWhitelist(_to[i], true);
        }
    }

    function removeFromWhitelistBulk(address[] memory _to) public onlyOwner {
        //be careful with out of gas in a loop
        for (uint i = 0; i < _to.length; i++) {
            _setWhitelist(_to[i], false);
        }
    }

    function transfer(address recipient, uint256 amount) public override isWhitelisted(recipient) returns (bool) {
        super.transfer(recipient, amount);
        return true;
    }

    function transferFrom(address sender, address recipient, uint256 amount) public virtual override isWhitelisted(recipient) returns (bool) {
        super.transferFrom(sender, recipient, amount);
        return true;
    }


    function _setWhitelist(address _to, bool _value) internal {
        whitelist[_to] = _value;
    }

    function _buyTokens(uint256 ETHAmount) private {
        uint256 amountToSend;

        if (
            block.timestamp >= round1.time
            && block.timestamp < round2.time
        ) {
            amountToSend = ETHAmount.mul(round1.price);
            
            if (round1.tokensAllocated < amountToSend) {
                
                amountToSend = round1.tokensAllocated;
                
                round1.tokensAllocated = 0;
               
                uint256 ETHToSendBack = ETHAmount.sub(
                    amountToSend
                        .mul(1 ether)
                        .div(
                            round1.price * 10 ** uint256(tokenDecimals)
                        )
                    );
    
                _msgSender().transfer(ETHToSendBack);
                
            } else {
                round1.tokensAllocated = round1.tokensAllocated.sub(amountToSend);
            }
            
            if (round1.tokensAllocated == 0) {
                round2.time = block.timestamp;
            }
        } else if (block.timestamp >= round2.time) {
            amountToSend = ETHAmount.mul(round2.price);
            
            if (round2.tokensAllocated < amountToSend) {
                amountToSend = round2.tokensAllocated;
                round2.tokensAllocated = 0;
                
                uint256 ETHToSendBack = ETHAmount.sub(
                    amountToSend
                        .mul(1 ether)
                        .div(
                            round2.price * 10 ** uint256(tokenDecimals)
                        )
                    );
                _msgSender().transfer(ETHToSendBack);
            } else {
                round2.tokensAllocated = round2.tokensAllocated.sub(amountToSend);
            }
        }
        if (amountToSend != 0) {
            _mint(_msgSender(), amountToSend);
        } else {
            revert("purchase was not successful");
        }
    }
}