// Sources flattened with hardhat v2.10.1-gzeon-c8fe47dd4 https://hardhat.org

// File contracts/lib/safe-math.sol

// SPDX-License-Identifier: MIT

pragma solidity 0.8.4;

/**
 * @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;
    }
}


// File contracts/lib/context.sol



pragma solidity 0.8.4;

/*
 * @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 payable(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;
    }
}


// File contracts/lib/erc20.sol

// File: contracts/GSN/Context.sol



pragma solidity 0.8.4;


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


/**
 * @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);
}

// File: contracts/utils/Address.sol


/**
 * @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 on 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);
            }
        }
    }
}

// File: contracts/token/ERC20/ERC20.sol

/**
 * @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 ERC20 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_) {
        _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.
     *
     * 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 { }
}

/**
 * @title SafeERC20
 * @dev Wrappers around ERC20 operations that throw on failure (when the token
 * contract returns false). Tokens that return no value (and instead revert or
 * throw on failure) are also supported, non-reverting calls are assumed to be
 * successful.
 * To use this library you can add a `using SafeERC20 for IERC20;` statement to your contract,
 * which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
 */
library SafeERC20 {
    using SafeMath for uint256;
    using Address for address;

    function safeTransfer(IERC20 token, address to, uint256 value) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
    }

    function safeTransferFrom(IERC20 token, address from, address to, uint256 value) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transferFrom.selector, from, to, value));
    }

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

    function safeIncreaseAllowance(IERC20 token, address spender, uint256 value) internal {
        uint256 newAllowance = token.allowance(address(this), spender).add(value);
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
    }

    function safeDecreaseAllowance(IERC20 token, address spender, uint256 value) internal {
        uint256 newAllowance = token.allowance(address(this), spender).sub(value, "SafeERC20: decreased allowance below zero");
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
    }

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

        bytes memory returndata = address(token).functionCall(data, "SafeERC20: low-level call failed");
        if (returndata.length > 0) { // Return data is optional
            // solhint-disable-next-line max-line-length
            require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
        }
    }
}


// File contracts/zapper/vault-zapper-1.sol

// Sources flattened with hardhat v2.9.9 https://hardhat.org

// File contracts/lib/safe-math.sol



pragma solidity 0.8.4;


// File contracts/interfaces/uniswapv2.sol


pragma solidity 0.8.4;

interface UniswapRouterV2 {
    function swapExactTokensForTokens(
        uint256 amountIn,
        uint256 amountOutMin,
        address[] calldata path,
        address to,
        uint256 deadline
    ) external returns (uint256[] memory amounts);

    function addLiquidity(
        address tokenA,
        address tokenB,
        uint256 amountADesired,
        uint256 amountBDesired,
        uint256 amountAMin,
        uint256 amountBMin,
        address to,
        uint256 deadline
    )
        external
        returns (
            uint256 amountA,
            uint256 amountB,
            uint256 liquidity
        );

    function addLiquidityETH(
        address token,
        uint256 amountTokenDesired,
        uint256 amountTokenMin,
        uint256 amountETHMin,
        address to,
        uint256 deadline
    )
        external
        payable
        returns (
            uint256 amountToken,
            uint256 amountETH,
            uint256 liquidity
        );

    function removeLiquidity(
        address tokenA,
        address tokenB,
        uint256 liquidity,
        uint256 amountAMin,
        uint256 amountBMin,
        address to,
        uint256 deadline
    ) external returns (uint256 amountA, uint256 amountB);

     function quote(
        uint256 amountA,
        uint256 reserveA,
        uint256 reserveB
    ) external pure returns (uint256 amountB);

     function getAmountOut(
        uint256 amountIn,
        uint256 reserveIn,
        uint256 reserveOut
    ) external pure returns (uint256 amountOut);

    function getAmountsOut(uint256 amountIn, address[] calldata path)
        external
        view
        returns (uint256[] memory amounts);

    function getAmountsIn(uint256 amountOut, address[] calldata path)
        external
        view
        returns (uint256[] memory amounts);

    function swapETHForExactTokens(
        uint256 amountOut,
        address[] calldata path,
        address to,
        uint256 deadline
    ) external payable returns (uint256[] memory amounts);

    function swapExactETHForTokens(
        uint256 amountOutMin,
        address[] calldata path,
        address to,
        uint256 deadline
    ) external payable returns (uint256[] memory amounts);
}

interface IUniswapV2Pair {
    event Approval(
        address indexed owner,
        address indexed spender,
        uint256 value
    );
    event Transfer(address indexed from, address indexed to, uint256 value);

    function name() external pure returns (string memory);

    function symbol() external pure returns (string memory);

    function decimals() external pure returns (uint8);

    function totalSupply() external view returns (uint256);

    function balanceOf(address owner) external view returns (uint256);

    function allowance(address owner, address spender)
        external
        view
        returns (uint256);

    function approve(address spender, uint256 value) external returns (bool);

    function transfer(address to, uint256 value) external returns (bool);

    function transferFrom(
        address from,
        address to,
        uint256 value
    ) external returns (bool);

    function DOMAIN_SEPARATOR() external view returns (bytes32);

    function PERMIT_TYPEHASH() external pure returns (bytes32);

    function nonces(address owner) external view returns (uint256);

    function permit(
        address owner,
        address spender,
        uint256 value,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external;

    event Mint(address indexed sender, uint256 amount0, uint256 amount1);
    event Burn(
        address indexed sender,
        uint256 amount0,
        uint256 amount1,
        address indexed to
    );
    event Swap(
        address indexed sender,
        uint256 amount0In,
        uint256 amount1In,
        uint256 amount0Out,
        uint256 amount1Out,
        address indexed to
    );
    event Sync(uint112 reserve0, uint112 reserve1);

    function MINIMUM_LIQUIDITY() external pure returns (uint256);

    function factory() external view returns (address);

    function token0() external view returns (address);

    function token1() external view returns (address);

    function getReserves()
        external
        view
        returns (
            uint112 reserve0,
            uint112 reserve1,
            uint32 blockTimestampLast
        );

    function price0CumulativeLast() external view returns (uint256);

    function price1CumulativeLast() external view returns (uint256);

    function kLast() external view returns (uint256);

    function mint(address to) external returns (uint256 liquidity);

    function burn(address to)
        external
        returns (uint256 amount0, uint256 amount1);

    function swap(
        uint256 amount0Out,
        uint256 amount1Out,
        address to,
        bytes calldata data
    ) external;

    function skim(address to) external;

    function sync() external;
}

interface IUniswapV2Factory {
    event PairCreated(
        address indexed token0,
        address indexed token1,
        address pair,
        uint256
    );

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

    function allPairs(uint256) external view returns (address pair);

    function allPairsLength() external view returns (uint256);

    function feeTo() external view returns (address);

    function feeToSetter() external view returns (address);

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


// File contracts/lib/square-root.sol

// File: @uniswap/lib/contracts/libraries/Babylonian.sol

pragma solidity 0.8.4;

// computes square roots using the babylonian method
// https://en.wikipedia.org/wiki/Methods_of_computing_square_roots#Babylonian_method
library Babylonian {
    // credit for this implementation goes to
    // https://github.com/abdk-consulting/abdk-libraries-solidity/blob/master/ABDKMath64x64.sol#L687
    function sqrt(uint256 x) internal pure returns (uint256) {
        if (x == 0) return 0;
        // this block is equivalent to r = uint256(1) << (BitMath.mostSignificantBit(x) / 2);
        // however that code costs significantly more gas
        uint256 xx = x;
        uint256 r = 1;
        if (xx >= 0x100000000000000000000000000000000) {
            xx >>= 128;
            r <<= 64;
        }
        if (xx >= 0x10000000000000000) {
            xx >>= 64;
            r <<= 32;
        }
        if (xx >= 0x100000000) {
            xx >>= 32;
            r <<= 16;
        }
        if (xx >= 0x10000) {
            xx >>= 16;
            r <<= 8;
        }
        if (xx >= 0x100) {
            xx >>= 8;
            r <<= 4;
        }
        if (xx >= 0x10) {
            xx >>= 4;
            r <<= 2;
        }
        if (xx >= 0x8) {
            r <<= 1;
        }
        r = (r + x / r) >> 1;
        r = (r + x / r) >> 1;
        r = (r + x / r) >> 1;
        r = (r + x / r) >> 1;
        r = (r + x / r) >> 1;
        r = (r + x / r) >> 1;
        r = (r + x / r) >> 1; // Seven iterations should be enough
        uint256 r1 = x / r;
        return (r < r1 ? r : r1);
    }
}


// File contracts/interfaces/weth.sol



pragma solidity 0.8.4;

interface WETH {
    function name() external view returns (string memory);

    function approve(address guy, uint256 wad) external returns (bool);

    function totalSupply() external view returns (uint256);

    function transferFrom(
        address src,
        address dst,
        uint256 wad
    ) external returns (bool);

    function withdraw(uint256 wad) external;

    function decimals() external view returns (uint8);

    function balanceOf(address) external view returns (uint256);

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

    function transfer(address dst, uint256 wad) external returns (bool);

    function deposit() external payable;

    function allowance(address, address) external view returns (uint256);
}


// File contracts/interfaces/vault.sol


pragma solidity 0.8.4;

interface IVault is IERC20 {
    function token() external view returns (address);
    
    function reward() external view returns (address);

    function claimInsurance() external; // NOTE: Only yDelegatedVault implements this

    function getRatio() external view returns (uint256);

    function depositAll() external;
    
    function balance() external view returns (uint256);

    function deposit(uint256) external;

    function withdrawAll() external;

    function withdraw(uint256) external;

    function earn() external;

    function decimals() external view returns (uint8);
}


// File contracts/zapper/zapper-base.sol

pragma solidity 0.8.4;

abstract contract ZapperBase {
    using SafeERC20 for IERC20;
    using Address for address;
    using SafeMath for uint256;
    using SafeERC20 for IVault;

    address public router;
    address public governance;

    // Define a mapping to store whether an address is whitelisted or not
    mapping(address => bool) public whitelistedVaults;

    address public constant weth = 0x82aF49447D8a07e3bd95BD0d56f35241523fBab1;

    uint256 public constant minimumAmount = 1000;

    constructor(
        address _router, 
        address _governance
    ){
        // Safety checks to ensure WETH token address
        WETH(weth).deposit{value: 0}();
        WETH(weth).withdraw(0);
        router = _router;
        governance = _governance;
    }

    receive() external payable {
        assert(msg.sender == weth);
    }

    // **** Modifiers **** //

    // Modifier to restrict access to whitelisted vaults only
    modifier onlyWhitelistedVaults(address vault) {
        require(whitelistedVaults[vault], "Vault is not whitelisted");
        _;
    }

    // Modifier to restrict access to governance only
    modifier onlyGovernance() {
        require(msg.sender == governance, "Caller is not the governance");
        _;
    }
    
    // Function to add a vault to the whitelist
    function addToWhitelist(address _vault) external onlyGovernance {
        whitelistedVaults[_vault] = true;
    }

    // Function to remove a vault from the whitelist
    function removeFromWhitelist(address _vault) external onlyGovernance {
        whitelistedVaults[_vault] = false;
    }

    function _getSwapAmount(uint256 investmentA, uint256 reserveA, uint256 reserveB) public view virtual returns (uint256 swapAmount);

    //returns DUST
    function _returnAssets(address[] memory tokens) internal {
        uint256 balance;
        for (uint256 i; i < tokens.length; i++) {
            balance = IERC20(tokens[i]).balanceOf(address(this));
            if (balance > 0) {
                if (tokens[i] == weth) {
                    WETH(weth).withdraw(balance);
                    (bool success, ) = msg.sender.call{value: balance}(
                        new bytes(0)
                    );
                    require(success, "ETH transfer failed");
                } else {
                    IERC20(tokens[i]).safeTransfer(msg.sender, balance);
                }
            }
        }
    }

    function _swapAndStake(address vault, uint256 tokenAmountOutMin, address tokenIn) public virtual;

    function zapInETH(address vault, uint256 tokenAmountOutMin, address tokenIn) external payable onlyWhitelistedVaults(vault){
        require(msg.value >= minimumAmount, "Insignificant input amount");

        WETH(weth).deposit{value: msg.value}();

        // allows us to zapIn if eth isn't part of the original pair
        if (tokenIn != weth){
            uint256 _amount = IERC20(weth).balanceOf(address(this));

            (, IUniswapV2Pair pair) = _getVaultPair(vault);

            (uint256 reserveA, uint256 reserveB, ) = pair.getReserves();
            require(reserveA > minimumAmount && reserveB > minimumAmount, "Liquidity pair reserves too low");

            bool isInputA = pair.token0() == tokenIn;
            require(isInputA || pair.token1() == tokenIn, "Input token not present in liquidity pair");

            address[] memory path = new address[](2);
            path[0] = weth;
            path[1] = tokenIn;

            uint256 swapAmountIn;
        
            swapAmountIn = _getSwapAmount(_amount, reserveA, reserveB);
       
            _approveTokenIfNeeded(path[0], address(router));
            UniswapRouterV2(router).swapExactTokensForTokens(
                swapAmountIn,
                tokenAmountOutMin,
                path,
                address(this),
                block.timestamp
            );
            _swapAndStake(vault, tokenAmountOutMin, tokenIn);
        }else{
            _swapAndStake(vault, tokenAmountOutMin, tokenIn);
        }
    }

    // transfers tokens from msg.sender to this contract 
    function zapIn(address vault, uint256 tokenAmountOutMin, address tokenIn, uint256 tokenInAmount) external onlyWhitelistedVaults(vault){
        require(tokenInAmount >= minimumAmount, "Insignificant input amount");
        require(IERC20(tokenIn).allowance(msg.sender, address(this)) >= tokenInAmount, "Input token is not approved");

        // transfer token 
        IERC20(tokenIn).safeTransferFrom(
            msg.sender,
            address(this),
            tokenInAmount
        );

        (, IUniswapV2Pair pair) = _getVaultPair(vault);

        if(tokenIn != pair.token0() && tokenIn != pair.token1()){
            (address desiredToken) = pair.token0();

            if(tokenIn != weth && desiredToken != weth){
                // execute swap from tokenin to desired token
                uint256 _amount = IERC20(tokenIn).balanceOf(address(this));

                address[] memory path = new address[](3);
                path[0] = tokenIn;
                path[1] = weth;
                path[2] = desiredToken;
        
                _approveTokenIfNeeded(path[0], address(router));
                UniswapRouterV2(router).swapExactTokensForTokens(
                    _amount,
                    tokenAmountOutMin,
                    path,
                    address(this),
                    block.timestamp
                );
            
            }else {
                // execute swap from tokenin to desired token
                uint256 _amount = IERC20(tokenIn).balanceOf(address(this));

                address[] memory path = new address[](2);
                path[0] = tokenIn;
                path[1] = desiredToken;
        
                _approveTokenIfNeeded(path[0], address(router));
                UniswapRouterV2(router).swapExactTokensForTokens(
                    _amount,
                    tokenAmountOutMin,
                    path,
                    address(this),
                    block.timestamp
                );
            }

            _swapAndStake(vault, tokenAmountOutMin, desiredToken);
        }else {
            _swapAndStake(vault, tokenAmountOutMin, tokenIn);
        }
    }

    function zapOutAndSwap(address vault, uint256 withdrawAmount, address desiredToken, uint256 desiredTokenOutMin) public virtual;

    function _removeLiquidity(address pair, address to) internal {
        IERC20(pair).safeTransfer(pair, IERC20(pair).balanceOf(address(this)));
        (uint256 amount0, uint256 amount1) = IUniswapV2Pair(pair).burn(to);

        require(amount0 >= minimumAmount, "Router: INSUFFICIENT_A_AMOUNT");
        require(amount1 >= minimumAmount, "Router: INSUFFICIENT_B_AMOUNT");
    }

    function _getVaultPair(address vault_addr) internal view returns (IVault vault, IUniswapV2Pair pair){

        vault = IVault(vault_addr);
        pair = IUniswapV2Pair(vault.token());

        require(pair.factory() == IUniswapV2Pair(router).factory(), "Incompatible liquidity pair factory");
    }

    function _approveTokenIfNeeded(address token, address spender) internal {
        if (IERC20(token).allowance(address(this), spender) == 0) {
            IERC20(token).safeApprove(spender, type(uint256).max);
        }
    }

    function zapOut(address vault_addr, uint256 withdrawAmount) external onlyWhitelistedVaults(vault_addr){
        (IVault vault, IUniswapV2Pair pair) = _getVaultPair(vault_addr);

        IERC20(vault_addr).safeTransferFrom(msg.sender, address(this), withdrawAmount);
        vault.withdraw(withdrawAmount);

        if (pair.token0() != weth && pair.token1() != weth) {
            return _removeLiquidity(address(pair), msg.sender);
        }


        _removeLiquidity(address(pair), address(this));

        address[] memory tokens = new address[](2);
        tokens[0] = pair.token0();
        tokens[1] = pair.token1();

        _returnAssets(tokens);
    }
}


// File contracts/zapper/vault-zapper.sol


pragma solidity 0.8.4;

contract VaultZapEthSushi is ZapperBase {
    using SafeERC20 for IERC20;
    using Address for address;
    using SafeMath for uint256;
    using SafeERC20 for IVault;

    constructor()
        ZapperBase(0x1b02dA8Cb0d097eB8D57A175b88c7D8b47997506, 0xCb410A689A03E06de0a6247b13C13D14237DecC8){}

    function zapOutAndSwap(address vault_addr, uint256 withdrawAmount, address desiredToken, uint256 desiredTokenOutMin) public override onlyWhitelistedVaults(vault_addr){
        (IVault vault, IUniswapV2Pair pair) = _getVaultPair(vault_addr);
        address token0 = pair.token0();
        address token1 = pair.token1();

        address firstToken = token0;

        vault.safeTransferFrom(msg.sender, address(this), withdrawAmount);
        vault.withdraw(withdrawAmount);
        _removeLiquidity(address(pair), address(this));

        address swapToken = token1 == firstToken ? token0 : token1;

        if(swapToken == weth || firstToken == weth){
            address[] memory path = new address[](2);
            path[0] = swapToken;
            path[1] = firstToken;

            _approveTokenIfNeeded(path[0], address(router));
            UniswapRouterV2(router).swapExactTokensForTokens(
                IERC20(swapToken).balanceOf(address(this)),
                desiredTokenOutMin,
                path,
                address(this),
                block.timestamp
            );

        }else {
            address[] memory path = new address[](3);
            path[0] = swapToken;
            path[1] = weth;
            path[2] = firstToken;

            _approveTokenIfNeeded(path[0], address(router));
            UniswapRouterV2(router).swapExactTokensForTokens(
                IERC20(swapToken).balanceOf(address(this)),
                desiredTokenOutMin,
                path,
                address(this),
                block.timestamp
            );
        }

        if(desiredToken != firstToken) {
            
            if(desiredToken == weth || firstToken == weth){
                address[] memory path1 = new address[](2);
                path1[0] = firstToken;
                path1[1] = desiredToken;

                _approveTokenIfNeeded(path1[0], address(router));
                UniswapRouterV2(router).swapExactTokensForTokens(
                    IERC20(firstToken).balanceOf(address(this)),
                    desiredTokenOutMin,
                    path1,
                    address(this),
                    block.timestamp
                );

                _returnAssets(path1); 

            }else {
                address[] memory path1 = new address[](3);
                path1[0] = firstToken;
                path1[1] = weth;
                path1[2] = desiredToken;

                _approveTokenIfNeeded(path1[0], address(router));
                UniswapRouterV2(router).swapExactTokensForTokens(
                    IERC20(firstToken).balanceOf(address(this)),
                    desiredTokenOutMin,
                    path1,
                    address(this),
                    block.timestamp
                );

                _returnAssets(path1); 
            }
        }

        address[] memory path2 = new address[](3);
        path2[0] = swapToken;
        path2[1] = weth;
        path2[2] = firstToken;

        _returnAssets(path2);
    }

    function zapOutAndSwapEth(address vault_addr, uint256 withdrawAmount, uint256 desiredTokenOutMin) public onlyWhitelistedVaults(vault_addr){
        (IVault vault, IUniswapV2Pair pair) = _getVaultPair(vault_addr);
        address token0 = pair.token0();
        address token1 = pair.token1();

        address desiredToken = token0; 

        vault.safeTransferFrom(msg.sender, address(this), withdrawAmount);
        vault.withdraw(withdrawAmount);
        _removeLiquidity(address(pair), address(this));

        address swapToken = token1 == desiredToken ? token0 : token1;

        if(swapToken == weth || desiredToken == weth){
            address[] memory path = new address[](2);
            path[0] = swapToken;
            path[1] = desiredToken;

            _approveTokenIfNeeded(path[0], address(router));
            UniswapRouterV2(router).swapExactTokensForTokens(
                IERC20(swapToken).balanceOf(address(this)),
                desiredTokenOutMin,
                path,
                address(this),
                block.timestamp
            );

        }else {
            address[] memory path = new address[](3);
            path[0] = swapToken;
            path[1] = weth;
            path[2] = desiredToken;

            _approveTokenIfNeeded(path[0], address(router));
            UniswapRouterV2(router).swapExactTokensForTokens(
                IERC20(swapToken).balanceOf(address(this)),
                desiredTokenOutMin,
                path,
                address(this),
                block.timestamp
            );
        }
       

        if(desiredToken != weth) {
            address[] memory path1 = new address[](2);
            path1[0] = desiredToken;
            path1[1] = weth;

            _approveTokenIfNeeded(path1[0], address(router));
            UniswapRouterV2(router).swapExactTokensForTokens(
                IERC20(desiredToken).balanceOf(address(this)),
                desiredTokenOutMin,
                path1,
                address(this),
                block.timestamp
            );

             _returnAssets(path1);

        }

        address[] memory path2 = new address[](3);
        path2[0] = swapToken;
        path2[1] = weth;
        path2[2] = desiredToken;

        _returnAssets(path2);
    }


    function _swapAndStake(address vault_addr, uint256 tokenAmountOutMin, address tokenIn) public override onlyWhitelistedVaults(vault_addr) {
        (IVault vault, IUniswapV2Pair pair) = _getVaultPair(vault_addr);

        (uint256 reserveA, uint256 reserveB, ) = pair.getReserves();
        require(reserveA > minimumAmount && reserveB > minimumAmount, "Liquidity pair reserves too low");

        bool isInputA = pair.token0() == tokenIn;
        require(isInputA || pair.token1() == tokenIn, "Input token not present in liquidity pair");

        address[] memory path = new address[](2);
        path[0] = tokenIn;
        path[1] = isInputA ? pair.token1() : pair.token0();

        uint256 fullInvestment = IERC20(tokenIn).balanceOf(address(this));
        uint256 swapAmountIn;
        if (isInputA) {
            swapAmountIn = _getSwapAmount(fullInvestment, reserveA, reserveB);
        } else {
            swapAmountIn = _getSwapAmount(fullInvestment, reserveB, reserveA);
        }

        _approveTokenIfNeeded(path[0], address(router));
        uint256[] memory swappedAmounts = UniswapRouterV2(router)
            .swapExactTokensForTokens(
                swapAmountIn,
                tokenAmountOutMin,
                path,
                address(this),
                block.timestamp
            );

        _approveTokenIfNeeded(path[1], address(router));
        (, , uint256 amountLiquidity) = UniswapRouterV2(router).addLiquidity(
            path[0],
            path[1],
            fullInvestment.sub(swappedAmounts[0]),
            swappedAmounts[1],
            1,
            1,
            address(this),
            block.timestamp
        );

        _approveTokenIfNeeded(address(pair), address(vault));
        vault.deposit(amountLiquidity);

        //taking receipt token and sending back to user
        vault.safeTransfer(msg.sender, vault.balanceOf(address(this)));

        _returnAssets(path);
    }

    function _getSwapAmount(uint256 investmentA, uint256 reserveA, uint256 reserveB) public view override returns (uint256 swapAmount) {
        uint256 halfInvestment = investmentA.div(2);
        uint256 nominator = UniswapRouterV2(router).getAmountOut(
            halfInvestment,
            reserveA,
            reserveB
        );
        uint256 denominator = UniswapRouterV2(router).quote(
            halfInvestment,
            reserveA.add(halfInvestment),
            reserveB.sub(nominator)
        );
        swapAmount = investmentA.sub(
            Babylonian.sqrt(
                (halfInvestment * halfInvestment * nominator) / denominator
            )
        );
    }

    function estimateSwap(address vault_addr, address tokenIn, uint256 fullInvestmentIn) public view returns (uint256 swapAmountIn, uint256 swapAmountOut, address swapTokenOut){
        (, IUniswapV2Pair pair) = _getVaultPair(vault_addr);

        bool isInputA = pair.token0() == tokenIn;
        require(isInputA || pair.token1() == tokenIn, "Input token not present in liquidity pair");

        (uint256 reserveA, uint256 reserveB, ) = pair.getReserves();
        (reserveA, reserveB) = isInputA ? (reserveA, reserveB) : (reserveB, reserveA);

        swapAmountIn = _getSwapAmount(fullInvestmentIn, reserveA, reserveB);
        swapAmountOut = UniswapRouterV2(router).getAmountOut(
            swapAmountIn,
            reserveA,
            reserveB
        );
        swapTokenOut = isInputA ? pair.token1() : pair.token0();
    }
}

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