// SPDX-License-Identifier: MIT

pragma solidity =0.6.12;


// 
/*
 * @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 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 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
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies in extcodesize, which returns 0 for contracts in
        // construction, since the code is only stored at the end of the
        // constructor execution.

        uint256 size;
        // solhint-disable-next-line no-inline-assembly
        assembly { size := extcodesize(account) }
        return size > 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://diligence.consensys.net/posts/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/v0.5.11/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");

        // solhint-disable-next-line avoid-low-level-calls, avoid-call-value
        (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 functionCall(target, data, "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");
        return _functionCallWithValue(target, data, value, errorMessage);
    }

    function _functionCallWithValue(address target, bytes memory data, uint256 weiValue, string memory errorMessage) private returns (bytes memory) {
        require(isContract(target), "Address: call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.call{ value: weiValue }(data);
        if (success) {
            return returndata;
        } else {
            // 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

                // solhint-disable-next-line no-inline-assembly
                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}

// 
/**
 * @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}.
 */
contract ERC20BurnableMaxSupply is Context, IERC20 {
    using SafeMath for uint256;
    using Address for address;

    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) public {
        _name = name;
        _symbol = symbol;
        _decimals = 18;
    }

    /**
     * @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.
     *
     * ADJUSTMENTS: Can only mint up to 13k (13e21) BBRA (burn + farm rewards have to be stable at lower than 13k)
     *
     * 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);

        if (_totalSupply.add(amount) > 13e21) {
            // if supply is over 13k after adding 'amount' check what is available to be minted (13e21 - current supply)
            // if it's greater than 0 then we can mint up to that amount
            // Eg totalSupply = 12,999e18 BBRA and amount to be minted is 10e18 BBRA. We can't mint 10e18 because it takes us over
            // hard cap. However we can mint a partial amount aka 13e21 - 12,999e18 = 1e18
            amount = uint256(13e21).sub(_totalSupply);

            // can't mint even a partial amount so we must exit the function
            if (amount == 0)
                return;
        }

        _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 { }
}

interface IUniswapV2Router01 {
    function factory() external pure returns (address);
    function WETH() external pure returns (address);

    function addLiquidity(
        address tokenA,
        address tokenB,
        uint amountADesired,
        uint amountBDesired,
        uint amountAMin,
        uint amountBMin,
        address to,
        uint deadline
    ) external returns (uint amountA, uint amountB, uint liquidity);
    function addLiquidityETH(
        address token,
        uint amountTokenDesired,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline
    ) external payable returns (uint amountToken, uint amountETH, uint liquidity);
    function removeLiquidity(
        address tokenA,
        address tokenB,
        uint liquidity,
        uint amountAMin,
        uint amountBMin,
        address to,
        uint deadline
    ) external returns (uint amountA, uint amountB);
    function removeLiquidityETH(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline
    ) external returns (uint amountToken, uint amountETH);
    function removeLiquidityWithPermit(
        address tokenA,
        address tokenB,
        uint liquidity,
        uint amountAMin,
        uint amountBMin,
        address to,
        uint deadline,
        bool approveMax, uint8 v, bytes32 r, bytes32 s
    ) external returns (uint amountA, uint amountB);
    function removeLiquidityETHWithPermit(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline,
        bool approveMax, uint8 v, bytes32 r, bytes32 s
    ) external returns (uint amountToken, uint amountETH);
    function swapExactTokensForTokens(
        uint amountIn,
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external returns (uint[] memory amounts);
    function swapTokensForExactTokens(
        uint amountOut,
        uint amountInMax,
        address[] calldata path,
        address to,
        uint deadline
    ) external returns (uint[] memory amounts);
    function swapExactETHForTokens(uint amountOutMin, address[] calldata path, address to, uint deadline)
        external
        payable
        returns (uint[] memory amounts);
    function swapTokensForExactETH(uint amountOut, uint amountInMax, address[] calldata path, address to, uint deadline)
        external
        returns (uint[] memory amounts);
    function swapExactTokensForETH(uint amountIn, uint amountOutMin, address[] calldata path, address to, uint deadline)
        external
        returns (uint[] memory amounts);
    function swapETHForExactTokens(uint amountOut, address[] calldata path, address to, uint deadline)
        external
        payable
        returns (uint[] memory amounts);

    function quote(uint amountA, uint reserveA, uint reserveB) external pure returns (uint amountB);
    function getAmountOut(uint amountIn, uint reserveIn, uint reserveOut) external pure returns (uint amountOut);
    function getAmountIn(uint amountOut, uint reserveIn, uint reserveOut) external pure returns (uint amountIn);
    function getAmountsOut(uint amountIn, address[] calldata path) external view returns (uint[] memory amounts);
    function getAmountsIn(uint amountOut, address[] calldata path) external view returns (uint[] memory amounts);
}

interface IUniswapV2Router02 is IUniswapV2Router01 {
    function removeLiquidityETHSupportingFeeOnTransferTokens(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline
    ) external returns (uint amountETH);
    function removeLiquidityETHWithPermitSupportingFeeOnTransferTokens(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline,
        bool approveMax, uint8 v, bytes32 r, bytes32 s
    ) external returns (uint amountETH);

    function swapExactTokensForTokensSupportingFeeOnTransferTokens(
        uint amountIn,
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external;
    function swapExactETHForTokensSupportingFeeOnTransferTokens(
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external payable;
    function swapExactTokensForETHSupportingFeeOnTransferTokens(
        uint amountIn,
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external;
}

interface IUniswapV2Factory {
    event PairCreated(address indexed token0, address indexed token1, address pair, uint);

    function feeTo() external view returns (address);
    function feeToSetter() external view returns (address);

    function getPair(address tokenA, address tokenB) external view returns (address pair);
    function allPairs(uint) external view returns (address pair);
    function allPairsLength() external view returns (uint);

    function createPair(address tokenA, address tokenB) external returns (address pair);

    function setFeeTo(address) external;
    function setFeeToSetter(address) external;
}

// 
/**
 * @dev Contract module which provides a basic access control mechanism, where
 * there is an account (an admin) that can be granted exclusive access to
 * specific functions.
 *
 * By default, the admin account will be the one that deploys the contract. This
 * can later be changed with {transferAdmin}.
 *
 * This module is used through inheritance. It will make available the modifier
 * `onlyAdmin`, which can be applied to your functions to restrict their use to
 * the owner.
 */
contract Administrable is Context {
    address private _admin;

    event AdminTransferred(address indexed previousAdmin, address indexed newAdmin);

    /**
     * @dev Initializes the contract setting the deployer as the initial admin.
     */
    constructor () internal {
        address msgSender = _msgSender();
        _admin = msgSender;
        emit AdminTransferred(address(0), msgSender);
    }

    /**
     * @dev Returns the address of the current admin.
     */
    function admin() public view returns (address) {
        return _admin;
    }

    /**
     * @dev Throws if called by any account other than the admin.
     */
    modifier onlyAdmin() {
        require(_admin == _msgSender(), "Administrable: caller is not the admin");
        _;
    }

    /**
     * @dev Leaves the contract without admin. It will not be possible to call
     * `onlyAdmin` functions anymore. Can only be called by the current admin.
     *
     * NOTE: Renouncing admin will leave the contract without an admin,
     * thereby removing any functionality that is only available to the admin.
     */
    function renounceAdmin() public virtual onlyAdmin {
        emit AdminTransferred(_admin, address(0));
        _admin = address(0);
    }

    /**
     * @dev Transfers admin of the contract to a new account (`newAdmin`).
     * Can only be called by the current ad,om.
     */
    function transferAdmin(address newAdmin) public virtual onlyAdmin {
        require(newAdmin != address(0), "Administrable: new admin is the zero address");
        emit AdminTransferred(_admin, newAdmin);
        _admin = newAdmin;
    }
}

// 
abstract contract ERC20Payable {

    event Received(address indexed sender, uint256 amount);

    receive() external payable {
        emit Received(msg.sender, msg.value);
    }
}

// 
interface ISecondaryToken {
    // placeholder interface for tokens generate from burn
    // could be used in future to pass the responsibility to a contract that
    // would then mint the burn with dynamic variables from nfts

    function mint(
        address account,
        uint256 amount
    ) external;
}

// 
interface IProtocolAdapter {
    // Gets adapted burn divisor
    function getBurnDivisor(address _user, uint256 _currentBurnDivisor) external view returns (uint256);

    // Gets adapted farm rewards multiplier
    function getRewardsMultiplier(address _user, uint256 _currentRewardsMultiplier) external view returns (uint256);
}

// 
/**
 * @dev Extension of {ERC20} that allows token holders to destroy both their own
 * tokens and those that they have an allowance for, in a way that can be
 * recognized off-chain (via event analysis).
 */
abstract contract ERC20Burnable is Context, ERC20BurnableMaxSupply {
    /**
     * @dev Destroys `amount` tokens from the caller. CANNOT BE USED TO BURN OTHER PEOPLES TOKENS
     * ONLY BBRA AND ONLY FROM THE PERSON CALLING THE FUNCTION
     *
     * See {ERC20-_burn}.
     */
    function burn(uint256 amount) public virtual {
        _burn(_msgSender(), amount);
    }
}

// 
// Boo with Governance.
// Ownership given to Farming contract and Adminship can be given to DAO contract
contract BooBankerResearchAssociation is ERC20BurnableMaxSupply("BooBanker Research Association", "BBRA"), ERC20Burnable, Ownable, Administrable, ERC20Payable {
    using SafeMath for uint256;

    // uniswap info
    address public uniswapV2Router;
    address public uniswapV2Pair;
    address public uniswapV2Factory;

    // the amount burned tokens every transfer, i.e. 255 = 0.4%, 100 = 1%, 50 = 2%, 40 = 2.5%
    uint256 public burnDivisor;
    // the amount tokens saved for liquidity lock every transfer, i.e. 255 = 0.4%, 100 = 1%, 50 = 2%, 40 = 2.5%
    uint256 public liquidityDivisor;

    // If any token should be minted from burned $bbra (not $brra)
    ISecondaryToken public burnToken;

    // Dynamic burn regulator (less burn with a certain number of nfts etc)
    IProtocolAdapter public protocolAdapter;

    // Whether the protocol should reward those that spend their gas fees locking liquidity
    bool public rewardLiquidityLockCaller;

    // Pause trading after listing until x block - can only be used once
    bool public canPause;
    uint256 public pauseUntilBlock;

    // Timestamp of last liquidity lock call
    uint256 public lastLiquidityLock;

    // 1% of all transfers are sent to marketing fund
    address public _devaddr;

    // Events
    event LiquidityLock(uint256 tokenAmount, uint256 ethAmount);
    event LiquidityBurn(uint256 lpTokenAmount);
    event CallerReward(address caller, uint256 tokenAmount);
    event BuyBack(uint256 ethAmount, uint256 tokenAmount);
    event ProtocolAdapterChange(address _newProtocol);

    constructor(uint256 _burnDivisor, uint256 _liquidityDivisor) public {

        burnDivisor = _burnDivisor;
        liquidityDivisor = _liquidityDivisor;
        _devaddr = msg.sender;
        rewardLiquidityLockCaller = true;
        canPause = true;
        // initial quantity, 13k tokens
        _mint(msg.sender, 13e21);
    }

    function transferFrom(address sender, address recipient, uint256 amount) public checkRunning virtual override returns (bool) {
        uint256 onePct = amount.div(100);
        uint256 liquidityAmount = amount.div(liquidityDivisor);
        // Use dynamic burn divisor if Adapter contract is set
        uint256 burnAmount = amount.div(
            ( address(protocolAdapter) != address(0)
                ? protocolAdapter.getBurnDivisor(pickHuman(sender, recipient), burnDivisor)
                : burnDivisor
            )
        );

        _burn(sender, burnAmount);

        // Should a secondary token be given to recipient from burn amount?
        //
        if(address(burnToken) != address(0)) {
            burnToken.mint(recipient, burnAmount);
        }

        super.transferFrom(sender, _devaddr, onePct);
        super.transferFrom(sender, address(this), liquidityAmount);
        return super.transferFrom(sender, recipient, amount.sub(burnAmount).sub(liquidityAmount).sub(onePct));
    }

    function transfer(address recipient, uint256 amount) public checkRunning virtual override returns (bool) {
        uint256 onePct = amount.div(100);
        uint256 liquidityAmount = amount.div(liquidityDivisor);
        // Use dynamic burn divisor if Adapter contract is set
        uint256 burnAmount = amount.div(
            ( address(protocolAdapter) != address(0)
                ? protocolAdapter.getBurnDivisor(pickHuman(msg.sender, recipient), burnDivisor)
                : burnDivisor
            )
        );

        // do nft adapter
        _burn(msg.sender, burnAmount);

        // Should a secondary token be given to recipient from burn amount?
        if(address(burnToken) != address(0)) {
            burnToken.mint(recipient, burnAmount);
        }

        super.transfer(_devaddr, onePct);
        super.transfer(address(this), liquidityAmount);
        return super.transfer(recipient, amount.sub(burnAmount).sub(liquidityAmount).sub(onePct));
    }

    // Check if _from is human when calculating ProtocolAdapter settings (like burn)
    // so that if you're buying from Uniswap the adjusted burn still works
    function pickHuman(address _from, address _to) public view returns (address) {
        uint256 _codeLength;
        assembly {_codeLength := extcodesize(_from)}
        return _codeLength == 0 ? _from : _to;
    }

    /**
     * @dev Throws if called by any account other than the admin or owner.
     */
    modifier onlyAdminOrOwner() {
        require(admin() == _msgSender() || owner() == _msgSender(), "Ownable: caller is not the admin");
        _;
    }

    // To be used to stop trading at listing - prevent bots from buying
    modifier checkRunning(){
        require(block.number > pauseUntilBlock, "Go away bot");
        _;
    }

    // Trading can only be paused once, ever. Setting pauseUntilBlock to 0 resumes trading after pausing.
    function setPauseUntilBlock(uint256 _pauseUntilBlock) public onlyAdminOrOwner {
        require(canPause || _pauseUntilBlock == 0, 'Pause has already been used once. If disabling pause set block to 0');
        pauseUntilBlock = _pauseUntilBlock;
        // after the first pause we can no longer pause the protocol
        canPause = false;
    }

    /**
     * @dev prevents contracts from interacting with functions that have this modifier
     */
    modifier isHuman() {
        address _addr = msg.sender;
        uint256 _codeLength;

        assembly {_codeLength := extcodesize(_addr)}

//        if (_codeLength == 0) {
//            // use assert to consume all of the bots gas, kek
//            assert(true == false, 'oh boy - bots get rekt');
//        }
        require(_codeLength == 0, "sorry humans only");
        _;
    }

    // Sell half of burned tokens, provides liquidity and locks it away forever
    // can only be called when balance is > 1 and last lock is more than 2 hours ago
    function lockLiquidity() public isHuman() {
        // bbra balance
        uint256 _bal = balanceOf(address(this));
        require(uniswapV2Pair != address(0), "UniswapV2Pair not set in contract yet");
        require(uniswapV2Router != address(0), "UniswapV2Router not set in contract yet");
        require(_bal >= 1e18, "Minimum of 1 BBRA before we can lock liquidity");
        require(balanceOf(msg.sender) >= 5e18, "You must own at least 5 BBra to call lock");

        // caller rewards
        uint256 _callerReward = 0;
        if (rewardLiquidityLockCaller) {
            // subtract caller fee - 2% always
            _callerReward = _bal.div(50);
            _bal = _bal.sub(_callerReward);
        }

        // calculate ratios of bbra-eth for lp
        uint256 bbraToEth = _bal.div(2);
        uint256 brraForLiq = _bal.sub(bbraToEth);

        // Eth Balance before swap
        uint256 startingBalance = address(this).balance;
        swapTokensForWeth(bbraToEth);

        // due to price movements after selling it is likely that less than the amount of
        // eth received will be used for locking
        // instead of making the left over eth locked away forever we can call buyAndBurn() to buy back Bbra with leftover Eth
        uint256 ethFromBbra = address(this).balance.sub(startingBalance);
        addLiquidity(brraForLiq, ethFromBbra);

        emit LiquidityLock(brraForLiq, ethFromBbra);

        // only reward caller after trade to prevent any possible reentrancy
        // check balance is still available
        if (_callerReward != 0) {
            // in case LP takes more tokens than we are expecting reward _callerReward or balanceOf(this) - whichever is smallest
            if(balanceOf(address(this)) >= _callerReward) {
                transfer(msg.sender, _callerReward);
            } else {
                transfer(msg.sender, balanceOf(address(this)));
            }
        }

        lastLiquidityLock = block.timestamp;
    }

    // If for some reason we get more eth than expect from uniswap at time of locking liquidity
    // we buy and burn whatever amount of Bbra we get
    // can optout of burn so that instead it's added to the next liquidity lock instead

    // NOTE: Buy back not working due to address(this) being the token that we're buying from uniswap - apparently they
    // don't accept that. Leaving the code here however for anyone that wishes to adapt it and "fix" it
//    function buyAndBurn(bool _burnTokens) public {
//        // check minimum amount
//        uint256 startingBbra = balanceOf(address(this));
//        uint256 startingEth = address(this).balance;
//
//        require(startingEth >= 5e16, 'Contract balance must be at least 0.05 eth before invoking buyAndBurn');
//
//        swapWethForTokens(address(this).balance);
//        uint256 buyBackAmount = startingBbra.sub(balanceOf(address(this)));
//
//        // if burn is active and we have bought some tokens back successfuly then burnnnn
//        // if burn == false then tokens purchased will be used in liquidity at next lockLiquidity() call
//        if(_burnTokens && buyBackAmount != 0) {
//            // burn whatever amount was bought
//            _burn(address(this), buyBackAmount);
//        }
//        emit BuyBack(startingEth.sub(address(this).balance), buyBackAmount);
//    }
//
//    // buys bbra with left over eth - only called by liquidity lock function or buy&burn function
//    function swapWethForTokens(uint256 ethAmount) internal {
//        address[] memory uniswapPairPath = new address[](2);
//        uniswapPairPath[0] = IUniswapV2Router02(uniswapV2Router).WETH();
//        uniswapPairPath[1] = address(this);
//
//        IUniswapV2Router02(uniswapV2Router)
//        .swapExactETHForTokensSupportingFeeOnTransferTokens{
//        value: ethAmount
//        }(
//            0,
//            uniswapPairPath,
//            address(this),
//            block.timestamp
//        );
//    }

    // swaps bra for eth - only called by liquidity lock function
    function swapTokensForWeth(uint256 tokenAmount) internal {
        address[] memory uniswapPairPath = new address[](2);
        uniswapPairPath[0] = address(this);
        uniswapPairPath[1] = IUniswapV2Router02(uniswapV2Router).WETH();

        _approve(address(this), uniswapV2Router, tokenAmount);

        IUniswapV2Router02(uniswapV2Router)
        .swapExactTokensForETHSupportingFeeOnTransferTokens(
            tokenAmount,
            0,
            uniswapPairPath,
            address(this),
            block.timestamp
        );
    }

    function addLiquidity(uint256 tokenAmount, uint256 ethAmount) internal {
        // approve uniswapV2Router to transfer Brra
        _approve(address(this), uniswapV2Router, tokenAmount);

        // provide liquidity
        IUniswapV2Router02(uniswapV2Router)
        .addLiquidityETH{
            value: ethAmount
        }(
            address(this),
            tokenAmount,
            0,
            0,
            address(this),
            block.timestamp
        );

        // check LP balance
        uint256 _lpBalance = IERC20(uniswapV2Pair).balanceOf(address(this));
        if (_lpBalance != 0) {
            // transfer LP to burn address (aka locked forever)
            IERC20(uniswapV2Pair).transfer(address(0), _lpBalance);
            // any left over eth is sent to marketing for buy backs - will be a very minimal amount
            payable(_devaddr).transfer(address(this).balance);
            emit LiquidityBurn(_lpBalance);
        }
    }

    // returns amount of LP locked permanently
    function lockedLpAmount() public view returns(uint256) {
        if (uniswapV2Pair == address(0)) {
            return 0;
        }

        return IERC20(uniswapV2Pair).balanceOf(address(0));
    }

    // Whether Bbra should reward the person that pays for the gas calling the liquidity lock
    function setRewardLiquidityLockCaller(bool _rewardLiquidityLockCaller) public onlyAdminOrOwner {
        rewardLiquidityLockCaller = _rewardLiquidityLockCaller;
    }

    // Updates secondary token that could be minted from burned supply of BBRA (like BOOB mints ECTO on burn)
    function setSecondaryBurnToken(ISecondaryToken _token) public onlyAdminOrOwner {
        // this prevents the secondary token being itself and therefore negating burn
        require(address(_token) != address(this), 'Secondary token cannot be itself');
        // can be anything else, 0x0 disables secondary token usage
        burnToken = _token;
    }

    // Sets contract that regulates dynamic burn rates (changeable by DAO)
    function setProtocolAdapter(IProtocolAdapter _contract) public onlyAdminOrOwner {
        // setting to 0x0 disabled dynamic burn and is defaulted to regular burn
        protocolAdapter = _contract;
        emit ProtocolAdapterChange(address(_contract));
    }

    // self explanatory
    function setBurnRate(uint256 _burnDivisor) public onlyAdminOrOwner {
        require(_burnDivisor != 0, "Boo: burnDivisor must be bigger than 0");
        burnDivisor = _burnDivisor;
    }

    // self explanatory
    function setLiquidityDivisor(uint256 _liquidityDivisor) public onlyAdminOrOwner {
        require(_liquidityDivisor != 0, "Boo: _liquidityDivisor must be bigger than 0");
        liquidityDivisor = _liquidityDivisor;
    }

    /// @dev Creates `_amount` token to `_to`. Must only be called by the owner (MrBanker), used to mint farming rewards
    // and nothing else
    function mint(address _to, uint256 _amount) public onlyOwner {
        _mint(_to, _amount);
        _moveDelegates(address(0), _delegates[_to], _amount);
    }

    // Sets marketing address (where 1% is deposited)
    // Only owner can modify this (MrBanker)
    function setDevAddr(address _dev) public onlyOwner {
        _devaddr = _dev;
    }

    // sets uniswap router and LP pair addresses (needed for buy-back/sell and liquidity lock)
    function setUniswapAddresses(address _uniswapV2Factory, address _uniswapV2Router) public onlyAdminOrOwner {
        require(_uniswapV2Factory != address(0) && _uniswapV2Router != address(0), 'Uniswap addresses cannot be empty');
        uniswapV2Factory = _uniswapV2Factory;
        uniswapV2Router = _uniswapV2Router;

        if (uniswapV2Pair == address(0)) {
            createUniswapPair();
        }
    }

    // create LP pair if one hasn't been created
    // can be public, doesn't matter who calls it
    function createUniswapPair() public {
        require(uniswapV2Pair == address(0), "Pair has already been created");
        require(uniswapV2Factory != address(0) && uniswapV2Router != address(0), "Uniswap addresses have not been set");

        uniswapV2Pair = IUniswapV2Factory(uniswapV2Factory).createPair(
                IUniswapV2Router02(uniswapV2Router).WETH(),
                address(this)
        );
    }

    // Copied and modified from YAM code:
    // https://github.com/yam-finance/yam-protocol/blob/master/contracts/token/YAMGovernanceStorage.sol
    // https://github.com/yam-finance/yam-protocol/blob/master/contracts/token/YAMGovernance.sol
    // Which is copied and modified from COMPOUND:
    // https://github.com/compound-finance/compound-protocol/blob/master/contracts/Governance/Comp.sol

    /// @dev A record of each accounts delegate
    mapping (address => address) internal _delegates;

    /// @dev A checkpoint for marking number of votes from a given block
    struct Checkpoint {
        uint32 fromBlock;
        uint256 votes;
    }

    /// @dev A record of votes checkpoints for each account, by index
    mapping (address => mapping (uint32 => Checkpoint)) public checkpoints;

    /// @dev The number of checkpoints for each account
    mapping (address => uint32) public numCheckpoints;

    /// @dev The EIP-712 typehash for the contract's domain
    bytes32 public constant DOMAIN_TYPEHASH = keccak256("EIP712Domain(string name,uint256 chainId,address verifyingContract)");

    /// @dev The EIP-712 typehash for the delegation struct used by the contract
    bytes32 public constant DELEGATION_TYPEHASH = keccak256("Delegation(address delegatee,uint256 nonce,uint256 expiry)");

    /// @dev A record of states for signing / validating signatures
    mapping (address => uint) public nonces;

    /// @dev An event thats emitted when an account changes its delegate
    event DelegateChanged(address indexed delegator, address indexed fromDelegate, address indexed toDelegate);

    /// @dev An event thats emitted when a delegate account's vote balance changes
    event DelegateVotesChanged(address indexed delegate, uint previousBalance, uint newBalance);

    /**
     * @dev Delegate votes from `msg.sender` to `delegatee`
     * @param delegator The address to get delegatee for
     */
    function delegates(address delegator)
    external
    view
    returns (address)
    {
        return _delegates[delegator];
    }

    /**
     * @dev Delegate votes from `msg.sender` to `delegatee`
     * @param delegatee The address to delegate votes to
     */
    function delegate(address delegatee) external {
        return _delegate(msg.sender, delegatee);
    }

    /**
     * @dev Delegates votes from signatory to `delegatee`
     * @param delegatee The address to delegate votes to
     * @param nonce The contract state required to match the signature
     * @param expiry The time at which to expire the signature
     * @param v The recovery byte of the signature
     * @param r Half of the ECDSA signature pair
     * @param s Half of the ECDSA signature pair
     */
    function delegateBySig(
        address delegatee,
        uint nonce,
        uint expiry,
        uint8 v,
        bytes32 r,
        bytes32 s
    )
    external
    {
        bytes32 domainSeparator = keccak256(
            abi.encode(
                DOMAIN_TYPEHASH,
                keccak256(bytes(name())),
                getChainId(),
                address(this)
            )
        );

        bytes32 structHash = keccak256(
            abi.encode(
                DELEGATION_TYPEHASH,
                delegatee,
                nonce,
                expiry
            )
        );

        bytes32 digest = keccak256(
            abi.encodePacked(
                "\x19\x01",
                domainSeparator,
                structHash
            )
        );

        address signatory = ecrecover(digest, v, r, s);
        require(signatory != address(0), "BOOB::delegateBySig: invalid signature");
        require(nonce == nonces[signatory]++, "BOOB::delegateBySig: invalid nonce");
        require(now <= expiry, "BOOB::delegateBySig: signature expired");
        return _delegate(signatory, delegatee);
    }

    /**
     * @dev Gets the current votes balance for `account`
     * @param account The address to get votes balance
     * @return The number of current votes for `account`
     */
    function getCurrentVotes(address account)
    external
    view
    returns (uint256)
    {
        uint32 nCheckpoints = numCheckpoints[account];
        return nCheckpoints > 0 ? checkpoints[account][nCheckpoints - 1].votes : 0;
    }

    /**
     * @dev Determine the prior number of votes for an account as of a block number
     * @dev Block number must be a finalized block or else this function will revert to prevent misinformation.
     * @param account The address of the account to check
     * @param blockNumber The block number to get the vote balance at
     * @return The number of votes the account had as of the given block
     */
    function getPriorVotes(address account, uint blockNumber)
    external
    view
    returns (uint256)
    {
        require(blockNumber < block.number, "BOOB::getPriorVotes: not yet determined");

        uint32 nCheckpoints = numCheckpoints[account];
        if (nCheckpoints == 0) {
            return 0;
        }

        // First check most recent balance
        if (checkpoints[account][nCheckpoints - 1].fromBlock <= blockNumber) {
            return checkpoints[account][nCheckpoints - 1].votes;
        }

        // Next check implicit zero balance
        if (checkpoints[account][0].fromBlock > blockNumber) {
            return 0;
        }

        uint32 lower = 0;
        uint32 upper = nCheckpoints - 1;
        while (upper > lower) {
            uint32 center = upper - (upper - lower) / 2; // ceil, avoiding overflow
            Checkpoint memory cp = checkpoints[account][center];
            if (cp.fromBlock == blockNumber) {
                return cp.votes;
            } else if (cp.fromBlock < blockNumber) {
                lower = center;
            } else {
                upper = center - 1;
            }
        }
        return checkpoints[account][lower].votes;
    }

    function _delegate(address delegator, address delegatee)
    internal
    {
        address currentDelegate = _delegates[delegator];
        uint256 delegatorBalance = balanceOf(delegator); // balance of underlying BOOBs (not scaled);
        _delegates[delegator] = delegatee;

        emit DelegateChanged(delegator, currentDelegate, delegatee);

        _moveDelegates(currentDelegate, delegatee, delegatorBalance);
    }

    function _moveDelegates(address srcRep, address dstRep, uint256 amount) internal {
        if (srcRep != dstRep && amount > 0) {
            if (srcRep != address(0)) {
                // decrease old representative
                uint32 srcRepNum = numCheckpoints[srcRep];
                uint256 srcRepOld = srcRepNum > 0 ? checkpoints[srcRep][srcRepNum - 1].votes : 0;
                uint256 srcRepNew = srcRepOld.sub(amount);
                _writeCheckpoint(srcRep, srcRepNum, srcRepOld, srcRepNew);
            }

            if (dstRep != address(0)) {
                // increase new representative
                uint32 dstRepNum = numCheckpoints[dstRep];
                uint256 dstRepOld = dstRepNum > 0 ? checkpoints[dstRep][dstRepNum - 1].votes : 0;
                uint256 dstRepNew = dstRepOld.add(amount);
                _writeCheckpoint(dstRep, dstRepNum, dstRepOld, dstRepNew);
            }
        }
    }

    function _writeCheckpoint(
        address delegatee,
        uint32 nCheckpoints,
        uint256 oldVotes,
        uint256 newVotes
    )
    internal
    {
        uint32 blockNumber = safe32(block.number, "BOOB::_writeCheckpoint: block number exceeds 32 bits");

        if (nCheckpoints > 0 && checkpoints[delegatee][nCheckpoints - 1].fromBlock == blockNumber) {
            checkpoints[delegatee][nCheckpoints - 1].votes = newVotes;
        } else {
            checkpoints[delegatee][nCheckpoints] = Checkpoint(blockNumber, newVotes);
            numCheckpoints[delegatee] = nCheckpoints + 1;
        }

        emit DelegateVotesChanged(delegatee, oldVotes, newVotes);
    }

    function safe32(uint n, string memory errorMessage) internal pure returns (uint32) {
        require(n < 2**32, errorMessage);
        return uint32(n);
    }

    function getChainId() internal pure returns (uint) {
        uint256 chainId;
        assembly { chainId := chainid() }
        return chainId;
    }
}