// File: contracts/RewardsHypervisor.sol



// SPDX-License-Identifier: BUSL-1.1

pragma solidity 0.7.6;

import "@openzeppelin/contracts/math/SafeMath.sol";
import "@openzeppelin/contracts/token/ERC20/ERC20.sol";
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts/token/ERC20/SafeERC20.sol";

import "@uniswap/v3-core/contracts/interfaces/IUniswapV3Pool.sol";
import "./visor/Visor.sol";

// @title Hypervisor
// @notice A Uniswap V2-like interface with fungible liquidity to Uniswap V3
// which allows for arbitrary liquidity provision: one-sided, lop-sided, and
// balanced
contract RewardsHypervisor is ERC20 {
    using SafeERC20 for IERC20;
    using SafeMath for uint256;

    IERC20 public visr;

    // @param _pool Uniswap V3 pool for which liquidity is managed
    // @param _owner Owner of the Hypervisor
    constructor(
        address _visr
    ) ERC20("Reward Visor", "RVISR") {
        visr = IERC20(_visr);
    }

    // @param visr Amount of VISR transfered from sender to Hypervisor
    // @param to Address to which liquidity tokens are minted
    // @param from Address from which tokens are transferred 
    // @return shares Quantity of liquidity tokens minted as a result of deposit
    function deposit(
        uint256 visrDeposit,
        address payable from,
        address to
    ) external returns (uint256 shares) {
        require(visrDeposit > 0, "deposits must be nonzero");
        require(to != address(0) && to != address(this), "to");
        require(from != address(0) && from != address(this), "from");

        shares = visrDeposit;
        if (totalSupply() != 0) {
          uint256 visrBalance = visr.balanceOf(address(this));
          shares = shares.mul(totalSupply()).div(visrBalance);
        }

				if(isContract(from)) {
					require(Visor(from).owner() == msg.sender); 
					Visor(from).delegatedTransferERC20(address(visr), address(this), visrDeposit);
				}
				else {
					visr.safeTransferFrom(from, address(this), visrDeposit);
				}

        _mint(to, shares);
    }

    // @param shares Number of rewards shares to redeem for VISR
    // @param to Address to which redeemed pool assets are sent
    // @param from Address from which liquidity tokens are sent
    // @return rewards Amount of visr redeemed by the submitted liquidity tokens
    function withdraw(
        uint256 shares,
        address to,
        address payable from
    ) external returns (uint256 rewards) {
        require(shares > 0, "shares");
        require(to != address(0), "to");

        rewards = visr.balanceOf(address(this)).mul(shares).div(totalSupply());
        visr.safeTransfer(to, rewards);

        require(from == msg.sender || Visor(from).owner() == msg.sender, "Sender must own the tokens");
        _burn(from, shares);
    }

		function isContract(address _addr) private returns (bool isContract){
				uint32 size;
				assembly {
					size := extcodesize(_addr)
				}
				return (size > 0);
		}

}

// File: @openzeppelin/contracts/math/SafeMath.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

/**
 * @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, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryAdd(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        uint256 c = a + b;
        if (c < a) return (false, 0);
        return (true, c);
    }

    /**
     * @dev Returns the substraction of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function trySub(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        if (b > a) return (false, 0);
        return (true, a - b);
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryMul(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
        // benefit is lost if 'b' is also tested.
        // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
        if (a == 0) return (true, 0);
        uint256 c = a * b;
        if (c / a != b) return (false, 0);
        return (true, c);
    }

    /**
     * @dev Returns the division of two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryDiv(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        if (b == 0) return (false, 0);
        return (true, a / b);
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryMod(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        if (b == 0) return (false, 0);
        return (true, a % b);
    }

    /**
     * @dev Returns the addition of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `+` operator.
     *
     * Requirements:
     *
     * - Addition cannot overflow.
     */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        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) {
        require(b <= a, "SafeMath: subtraction overflow");
        return a - b;
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `*` operator.
     *
     * Requirements:
     *
     * - Multiplication cannot overflow.
     */
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        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, reverting 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) {
        require(b > 0, "SafeMath: division by zero");
        return a / b;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b > 0, "SafeMath: modulo by zero");
        return a % b;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {trySub}.
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b <= a, errorMessage);
        return a - b;
    }

    /**
     * @dev Returns the integer division of two unsigned integers, reverting with custom message on
     * division by zero. The result is rounded towards zero.
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {tryDiv}.
     *
     * 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);
        return a / b;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting with custom message when dividing by zero.
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {tryMod}.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b > 0, errorMessage);
        return a % b;
    }
}

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



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

import "../../utils/Context.sol";
import "./IERC20.sol";
import "../../math/SafeMath.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;

    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 virtual returns (string memory) {
        return _name;
    }

    /**
     * @dev Returns the symbol of the token, usually a shorter version of the
     * name.
     */
    function symbol() public view virtual 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 virtual returns (uint8) {
        return _decimals;
    }

    /**
     * @dev See {IERC20-totalSupply}.
     */
    function totalSupply() public view virtual override returns (uint256) {
        return _totalSupply;
    }

    /**
     * @dev See {IERC20-balanceOf}.
     */
    function balanceOf(address account) public view virtual 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 virtual {
        _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 { }
}

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



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

/**
 * @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: @openzeppelin/contracts/token/ERC20/SafeERC20.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

import "./IERC20.sol";
import "../../math/SafeMath.sol";
import "../../utils/Address.sol";

/**
 * @title SafeERC20
 * @dev Wrappers around ERC20 operations that throw on failure (when the token
 * contract returns false). Tokens that return no value (and instead revert or
 * throw on failure) are also supported, non-reverting calls are assumed to be
 * successful.
 * To use this library you can add a `using SafeERC20 for IERC20;` statement to your contract,
 * which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
 */
library SafeERC20 {
    using 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: @uniswap/v3-core/contracts/interfaces/IUniswapV3Pool.sol



// SPDX-License-Identifier: GPL-2.0-or-later
pragma solidity >=0.5.0;

import './pool/IUniswapV3PoolImmutables.sol';
import './pool/IUniswapV3PoolState.sol';
import './pool/IUniswapV3PoolDerivedState.sol';
import './pool/IUniswapV3PoolActions.sol';
import './pool/IUniswapV3PoolOwnerActions.sol';
import './pool/IUniswapV3PoolEvents.sol';

/// @title The interface for a Uniswap V3 Pool
/// @notice A Uniswap pool facilitates swapping and automated market making between any two assets that strictly conform
/// to the ERC20 specification
/// @dev The pool interface is broken up into many smaller pieces
interface IUniswapV3Pool is
    IUniswapV3PoolImmutables,
    IUniswapV3PoolState,
    IUniswapV3PoolDerivedState,
    IUniswapV3PoolActions,
    IUniswapV3PoolOwnerActions,
    IUniswapV3PoolEvents
{

}

// File: contracts/visor/Visor.sol



// SPDX-License-Identifier: GPL-3.0-only
pragma solidity 0.7.6;
pragma abicoder v2;

import {SafeMath} from "@openzeppelin/contracts/math/SafeMath.sol";
import {IERC20} from "@openzeppelin/contracts/token/ERC20/IERC20.sol";

import {IERC721} from "@openzeppelin/contracts/token/ERC721/IERC721.sol";
import {IERC721Receiver} from "@openzeppelin/contracts/token/ERC721/IERC721Receiver.sol";

import {Initializable} from "@openzeppelin/contracts/proxy/Initializable.sol";
import {EnumerableSet} from "@openzeppelin/contracts/utils/EnumerableSet.sol";
import {Address} from "@openzeppelin/contracts/utils/Address.sol";
import {TransferHelper} from "@uniswap/lib/contracts/libraries/TransferHelper.sol";

import {EIP712} from "./EIP712.sol";
import {ERC1271} from "./ERC1271.sol";
import {OwnableERC721} from "./OwnableERC721.sol";
import {IRageQuit} from "../hypervisor/Hypervisor.sol";

import {IUniversalVault} from "../interfaces/IUniversalVault.sol";
import {IVisorService} from "../interfaces/IVisorService.sol";

/// @title Visor
/// @notice Vault for isolated storage of staking tokens
/// @dev Warning: not compatible with rebasing tokens
contract Visor is
    IUniversalVault,
    EIP712("UniversalVault", "1.0.0"),
    ERC1271,
    OwnableERC721,
    Initializable,
    IERC721Receiver
{
    using SafeMath for uint256;
    using Address for address;
    using Address for address payable;
    using EnumerableSet for EnumerableSet.Bytes32Set;

    /* constant */

    // Hardcoding a gas limit for rageQuit() is required to prevent gas DOS attacks
    // the gas requirement cannot be determined at runtime by querying the delegate
    // as it could potentially be manipulated by a malicious delegate who could force
    // the calls to revert.
    // The gas limit could alternatively be set upon vault initialization or creation
    // of a lock, but the gas consumption trade-offs are not favorable.
    // Ultimately, to avoid a need for fixed gas limits, the EVM would need to provide
    // an error code that allows for reliably catching out-of-gas errors on remote calls.
    uint256 public constant RAGEQUIT_GAS = 500000;
    bytes32 public constant LOCK_TYPEHASH =
        keccak256("Lock(address delegate,address token,uint256 amount,uint256 nonce)");
    bytes32 public constant UNLOCK_TYPEHASH =
        keccak256("Unlock(address delegate,address token,uint256 amount,uint256 nonce)");

    string public constant VERSION = "VISOR-2.0.5";

    /* storage */

    string public uri;
    uint256 private _nonce;
    mapping(bytes32 => LockData) private _locks;
    EnumerableSet.Bytes32Set private _lockSet;

    struct Nft {
      uint256 tokenId; 
      address nftContract;
    }

    mapping(bytes32 => Nft) private _nfts;
    EnumerableSet.Bytes32Set private _nftSet;

    mapping(bytes32=>bool) public nftApprovals;
    mapping(bytes32=>uint256) public erc20Approvals;

    struct TimelockERC20 {
      address recipient;
      address token;
      uint256 amount;
      uint256 expires;
    }

    mapping(bytes32=>TimelockERC20) public timelockERC20s; 
    mapping(address=>EnumerableSet.Bytes32Set) private timelockERC20Keys;
    mapping(address=>uint256) public timelockERC20Balances;

    struct TimelockERC721 {
      address recipient;
      address nftContract;
      uint256 tokenId;
      uint256 expires;
    }

    mapping(bytes32=>TimelockERC721) public timelockERC721s; 
    mapping(address=>EnumerableSet.Bytes32Set) private timelockERC721Keys;

    event AddNftToken(address nftContract, uint256 tokenId);
    event RemoveNftToken(address nftContract, uint256 tokenId);
    event TimeLockERC20(address recipient, address token, uint256 amount, uint256 expires);
    event TimeUnlockERC20(address recipient, address token, uint256 amount, uint256 expires);
    event TimeLockERC721(address recipient, address nftContract, uint256 tokenId, uint256 expires);
    event TimeUnlockERC721(address recipient, address nftContract, uint256 tokenId, uint256 expires);

    /* initialization function */

    function initializeLock() external initializer {}

    function initialize() external override initializer {
      OwnableERC721._setNFT(msg.sender);
    }

    /* ether receive */

    receive() external payable {}

    /* internal  */

    function _addNft(address nftContract, uint256 tokenId) internal {

      bytes32 key = calculateNftID(nftContract, tokenId);
      // add nft to set
      assert(_nftSet.add(key));
      // add nft data to storage
      _nfts[key] = Nft(tokenId, nftContract);
      emit AddNftToken(nftContract, tokenId);
    }

    function _removeNft(address nftContract, uint256 tokenId) internal {
      bytes32 key = calculateNftID(nftContract, tokenId);      
      // update nft storage
      assert(_nftSet.remove(key));
      delete _nfts[key];
      emit RemoveNftToken(nftContract, tokenId);
    }

    function setURI(string memory _uri) public onlyOwner {
        uri = _uri;
    }

    function _getOwner() internal view override(ERC1271) returns (address ownerAddress) {
        return OwnableERC721.owner();
    }

    /* pure functions */

    function calculateLockID(address delegate, address token)
        public
        pure
        override
        returns (bytes32 lockID)
    {
        return keccak256(abi.encodePacked(delegate, token));
    }

    function calculateNftID(address nftContract, uint256 tokenId)
        public
        pure
        returns (bytes32 nftId)
    {
        return keccak256(abi.encodePacked(nftContract, tokenId));
    }

    /* getter functions */

    function getPermissionHash(
        bytes32 eip712TypeHash,
        address delegate,
        address token,
        uint256 amount,
        uint256 nonce
    ) public view override returns (bytes32 permissionHash) {
        return
            EIP712._hashTypedDataV4(
                keccak256(abi.encode(eip712TypeHash, delegate, token, amount, nonce))
            );
    }

    function getNonce() external view override returns (uint256 nonce) {
        return _nonce;
    }

    function owner()
        public
        view
        override(IUniversalVault, OwnableERC721)
        returns (address ownerAddress)
    {
        return OwnableERC721.owner();
    }

    function getLockSetCount() external view override returns (uint256 count) {
        return _lockSet.length();
    }

    function getLockAt(uint256 index) external view override returns (LockData memory lockData) {
        return _locks[_lockSet.at(index)];
    }

    function getBalanceDelegated(address token, address delegate)
        external
        view
        override
        returns (uint256 balance)
    {
        return _locks[calculateLockID(delegate, token)].balance;
    }

    function getBalanceLocked(address token) public view override returns (uint256 balance) {
        uint256 count = _lockSet.length();
        for (uint256 index; index < count; index++) {
            LockData storage _lockData = _locks[_lockSet.at(index)];
            if (_lockData.token == token && _lockData.balance > balance)
                balance = _lockData.balance;
        }
        return balance;
    }

    function checkBalances() external view override returns (bool validity) {
        // iterate over all token locks and validate sufficient balance
        uint256 count = _lockSet.length();
        for (uint256 index; index < count; index++) {
            // fetch storage lock reference
            LockData storage _lockData = _locks[_lockSet.at(index)];
            // if insufficient balance and no∏t shutdown, return false
            if (IERC20(_lockData.token).balanceOf(address(this)) < _lockData.balance) return false;
        }
        // if sufficient balance or shutdown, return true
        return true;
    }

    // @notice Get ERC721 from nfts[] by index
    /// @param index nfts index of nfts[] 
    function getNFTByIndex(uint256 index) external view returns (Nft memory nftData) {
        require(index < _nftSet.length(), "ID overflow");
        return _nfts[_nftSet.at(index)];
    }

    // @notice Get number of timelocks for given ERC20 token 
    function getTimeLockCount(address token) external view returns(uint256) {
      return timelockERC20Keys[token].length();
    }

    // @notice Get number of timelocks for NFTs of a given ERC721 contract 
    function getTimeLockERC721Count(address nftContract) external view returns(uint256) {
      return timelockERC721Keys[nftContract].length();
    }

    /* user functions */

    /// @notice Lock ERC20 tokens in the vault
    /// access control: called by delegate with signed permission from owner
    /// state machine: anytime
    /// state scope:
    /// - insert or update _locks
    /// - increase _nonce
    /// token transfer: none
    /// @param token Address of token being locked
    /// @param amount Amount of tokens being locked
    /// @param permission Permission signature payload
    function lock(
        address token,
        uint256 amount,
        bytes calldata permission
    )
        external
        override
        onlyValidSignature(
            getPermissionHash(LOCK_TYPEHASH, msg.sender, token, amount, _nonce),
            permission
        )
    {
        // get lock id
        bytes32 lockID = calculateLockID(msg.sender, token);

        // add lock to storage
        if (_lockSet.contains(lockID)) {
            // if lock already exists, increase amount
            _locks[lockID].balance = _locks[lockID].balance.add(amount);
        } else {
            // if does not exist, create new lock
            // add lock to set
            assert(_lockSet.add(lockID));
            // add lock data to storage
            _locks[lockID] = LockData(msg.sender, token, amount);
        }

        // validate sufficient balance
        require(
            IERC20(token).balanceOf(address(this)) >= _locks[lockID].balance,
            "UniversalVault: insufficient balance"
        );

        // increase nonce
        _nonce += 1;

        // emit event
        emit Locked(msg.sender, token, amount);
    }

    /// @notice Unlock ERC20 tokens in the vault
    /// access control: called by delegate with signed permission from owner
    /// state machine: after valid lock from delegate
    /// state scope:
    /// - remove or update _locks
    /// - increase _nonce
    /// token transfer: none
    /// @param token Address of token being unlocked
    /// @param amount Amount of tokens being unlocked
    /// @param permission Permission signature payload
    function unlock(
        address token,
        uint256 amount,
        bytes calldata permission
    )
        external
        override
        onlyValidSignature(
            getPermissionHash(UNLOCK_TYPEHASH, msg.sender, token, amount, _nonce),
            permission
        )
    {
        // get lock id
        bytes32 lockID = calculateLockID(msg.sender, token);

        // validate existing lock
        require(_lockSet.contains(lockID), "UniversalVault: missing lock");

        // update lock data
        if (_locks[lockID].balance > amount) {
            // substract amount from lock balance
            _locks[lockID].balance = _locks[lockID].balance.sub(amount);
        } else {
            // delete lock data
            delete _locks[lockID];
            assert(_lockSet.remove(lockID));
        }

        // increase nonce
        _nonce += 1;

        // emit event
        emit Unlocked(msg.sender, token, amount);
    }

    /// @notice Forcibly cancel delegate lock
    /// @dev This function will attempt to notify the delegate of the rage quit using
    ///      a fixed amount of gas.
    /// access control: only owner
    /// state machine: after valid lock from delegate
    /// state scope:
    /// - remove item from _locks
    /// token transfer: none
    /// @param delegate Address of delegate
    /// @param token Address of token being unlocked
    function rageQuit(address delegate, address token)
        external
        override
        onlyOwner
        returns (bool notified, string memory error)
    {
        // get lock id
        bytes32 lockID = calculateLockID(delegate, token);

        // validate existing lock
        require(_lockSet.contains(lockID), "UniversalVault: missing lock");

        // attempt to notify delegate
        if (delegate.isContract()) {
            // check for sufficient gas
            require(gasleft() >= RAGEQUIT_GAS, "UniversalVault: insufficient gas");

            // attempt rageQuit notification
            try IRageQuit(delegate).rageQuit{gas: RAGEQUIT_GAS}() {
                notified = true;
            } catch Error(string memory res) {
                notified = false;
                error = res;
            } catch (bytes memory) {
                notified = false;
            }
        }

        // update lock storage
        assert(_lockSet.remove(lockID));
        delete _locks[lockID];

        // emit event
        emit RageQuit(delegate, token, notified, error);
    }

    /// @notice Transfer ERC20 tokens out of vault
    /// access control: only owner
    /// state machine: when balance >= max(lock) + amount
    /// state scope: none
    /// token transfer: transfer any token
    /// @param token Address of token being transferred
    /// @param to Address of the to
    /// @param amount Amount of tokens to transfer
    function transferERC20(
        address token,
        address to,
        uint256 amount
    ) external override onlyOwner {
        // check for sufficient balance
        require(
            IERC20(token).balanceOf(address(this)) >= (getBalanceLocked(token).add(amount)).add(timelockERC20Balances[token]),
            "UniversalVault: insufficient balance"
        );
        // perform transfer
        TransferHelper.safeTransfer(token, to, amount);
    }

    // @notice Approve delegate account to transfer ERC20 tokens out of vault
    /// @param token Address of token being transferred
    /// @param delegate Address being approved
    /// @param amount Amount of tokens approved to transfer
    function approveTransferERC20(address token, address delegate, uint256 amount) external onlyOwner {
      erc20Approvals[keccak256(abi.encodePacked(delegate, token))] = amount;
    }

    /// @notice Transfer ERC20 tokens out of vault with an approved account
    /// access control: only approved accounts in erc20Approvals 
    /// state machine: when balance >= max(lock) + amount
    /// state scope: none
    /// token transfer: transfer any token
    /// @param token Address of token being transferred
    /// @param to Address of the to
    /// @param amount Amount of tokens to transfer
    function delegatedTransferERC20(
        address token,
        address to,
        uint256 amount
    ) external {

        bytes32 key = keccak256(abi.encodePacked(msg.sender, token));
        // check for sufficient balance
        require(
            IERC20(token).balanceOf(address(this)) >= (getBalanceLocked(token).add(amount)).add(timelockERC20Balances[token]),
            "UniversalVault: insufficient balance"
        );
        erc20Approvals[key] = erc20Approvals[key].sub(amount);
        
        // perform transfer
        TransferHelper.safeTransfer(token, to, amount);
    }

    /// @notice Transfer ETH out of vault
    /// access control: only owner
    /// state machine: when balance >= amount
    /// state scope: none
    /// token transfer: transfer any token
    /// @param to Address of the to
    /// @param amount Amount of ETH to transfer
    function transferETH(address to, uint256 amount) external payable override onlyOwner {
      // perform transfer
      TransferHelper.safeTransferETH(to, amount);
    }

    // @notice Approve delegate account to transfer ERC721 token out of vault
    /// @param delegate Account address being approved to transfer nft  
    /// @param nftContract address of nft minter 
    /// @param tokenId token id of the nft instance 
    /// @param approved approval boolean value 
    function approveTransferERC721(
      address delegate, 
      address nftContract, 
      uint256 tokenId,
      bool approved
    ) external onlyOwner {
      nftApprovals[keccak256(abi.encodePacked(delegate, nftContract, tokenId))] = approved;
    }

    /// @notice Transfer ERC721 out of vault
    /// access control: only owner or approved
    /// ERC721 transfer: transfer any ERC721 token
    /// @param to recipient address 
    /// @param nftContract address of nft minter 
    /// @param tokenId token id of the nft instance 
    function transferERC721(
        address to,
        address nftContract,
        uint256 tokenId
    ) external {
        if(msg.sender != _getOwner()) {
          bytes32 key = keccak256(abi.encodePacked(msg.sender, nftContract, tokenId));
          require( nftApprovals[key], "NFT not approved for transfer"); 
          nftApprovals[key] = false;
        } 

        for(uint256 i=0; i<timelockERC721Keys[nftContract].length(); i++) {
          bytes32 key = timelockERC721Keys[nftContract].at(i);
          if(tokenId == timelockERC721s[key].tokenId) {
              require(
                timelockERC721s[key].expires <= block.timestamp, 
                "NFT locked and not expired"
              );
              require( timelockERC721s[key].recipient == msg.sender, "NFT locked and must be withdrawn by timelock recipient");
              delete timelockERC721s[key];
              timelockERC721Keys[nftContract].remove(key);
              break;
          }
        }

        _removeNft(nftContract, tokenId);
        IERC721(nftContract).safeTransferFrom(address(this), to, tokenId);
    }

    // @notice Adjust nfts[] on ERC721 token recieved 
    function onERC721Received(address operator, address from, uint256 tokenId, bytes calldata) external override returns (bytes4) {
      require(owner() == from, "From address is not the owner");
      _addNft(msg.sender, tokenId);
      return IERC721Receiver.onERC721Received.selector;
    }

    // @notice Lock ERC721 in vault until expires, redeemable by recipient
    /// @param recipient Address with right to withdraw after expires 
    /// @param nftContract address of nft minter 
    /// @param tokenId Token id of the nft instance 
    /// @param expires Timestamp when recipient is allowed to withdraw 
    function timeLockERC721(address recipient, address nftContract, uint256 tokenId, uint256 expires) external onlyOwner {

      require(
        expires > block.timestamp, 
        "Expires must be in future"
      );
 
      bytes32 key = keccak256(abi.encodePacked(recipient, nftContract, tokenId, expires)); 

      require(
        timelockERC721s[key].expires == 0,
        "TimelockERC721 already exists"
      );
     
      timelockERC721s[key] = TimelockERC721({
          recipient: recipient,
          nftContract: nftContract,
          tokenId: tokenId,
          expires: expires
      });

      timelockERC721Keys[nftContract].add(key);

      IERC721(nftContract).safeTransferFrom(msg.sender, address(this), tokenId);
      emit TimeLockERC721(recipient, nftContract, tokenId, expires);
    }

    // @notice Withdraw ERC721 in vault post expires by recipient
    /// @param recipient Address with right to withdraw after expires 
    /// @param nftContract address of nft minter 
    /// @param tokenId Token id of the nft instance 
    /// @param expires Timestamp when recipient is allowed to withdraw
    function timeUnlockERC721(address recipient, address nftContract, uint256 tokenId, uint256 expires) external {

      bytes32 key = keccak256(abi.encodePacked(recipient, nftContract, tokenId, expires)); 
      require(
        timelockERC721s[key].expires <= block.timestamp,
        "Not expired yet"
      );

      require(msg.sender == timelockERC721s[key].recipient, "Not recipient");

      _removeNft(nftContract, tokenId);
      delete timelockERC721s[key];
      timelockERC721Keys[nftContract].remove(key);

      IERC721(nftContract).safeTransferFrom(address(this), recipient, tokenId);
      emit TimeUnlockERC721(recipient, nftContract, tokenId, expires);
    }

    // @notice Lock ERC720 amount in vault until expires, redeemable by recipient
    /// @param recipient Address with right to withdraw after expires 
    /// @param token Address of token to lock 
    /// @param amount Amount of token to lock 
    /// @param expires Timestamp when recipient is allowed to withdraw
    function timeLockERC20(address recipient, address token, uint256 amount, uint256 expires) external onlyOwner {

      require(
        IERC20(token).allowance(msg.sender, address(this)) >= amount, 
        "Amount not approved"
      );

      require(
        expires > block.timestamp, 
        "Expires must be in future"
      );

      bytes32 key = keccak256(abi.encodePacked(recipient, token, amount, expires)); 

      require(
        timelockERC20s[key].expires == 0,
        "TimelockERC20 already exists"
      );
    
      timelockERC20s[key] = TimelockERC20({
          recipient: recipient,
          token: token,
          amount: amount,
          expires: expires
      });
      timelockERC20Keys[token].add(key);
      timelockERC20Balances[token] = timelockERC20Balances[token].add(amount);
      TransferHelper.safeTransferFrom(token, msg.sender, address(this), amount);
      emit TimeLockERC20(recipient, token, amount, expires);
    }

    // @notice Withdraw ERC20 from vault post expires by recipient
    /// @param recipient Address with right to withdraw after expires 
    /// @param token Address of token to lock 
    /// @param amount Amount of token to lock 
    /// @param expires Timestamp when recipient is allowed to withdraw
    function timeUnlockERC20(address recipient, address token, uint256 amount, uint256 expires) external {

      require(
        IERC20(token).balanceOf(address(this)) >= getBalanceLocked(token).add(amount),
        "Insufficient balance"
      );

      bytes32 key = keccak256(abi.encodePacked(recipient, token, amount, expires)); 
      require(
        timelockERC20s[key].expires <= block.timestamp,
        "Not expired yet"
      );

      require(msg.sender == timelockERC20s[key].recipient, "Not recipient");
      
      delete timelockERC20s[key];
      timelockERC20Keys[token].remove(key);

      timelockERC20Balances[token] = timelockERC20Balances[token].sub(amount);
      TransferHelper.safeTransfer(token, recipient, amount);
      emit TimeUnlockERC20(recipient, token, amount, expires);
    }

    // @notice get timelockERC20Key by address and index
    /// @param token Address of token
    /// @param index index of keys Bytes32Set 
    function getTimelockERC20Key(address token, uint256 index) external returns(bytes32) {
      require(timelockERC20Keys[token].length() > 0 && timelockERC20Keys[token].length() > index, "Index should be smaller than count");
      return timelockERC20Keys[token].at(index);
    }

    // @notice get timelockERC721Key by address and index
    /// @param nftContract Address of token
    /// @param index index of keys Bytes32Set 
    function getTimelockERC721Key(address nftContract, uint256 index) external returns(bytes32) {
      require(timelockERC721Keys[nftContract].length() > 0 && timelockERC721Keys[nftContract].length() > index, "Index should be smaller than count");
      return timelockERC721Keys[nftContract].at(index);
    }
}

// File: @openzeppelin/contracts/utils/Context.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

/*
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with 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;
    }
}

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



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.2 <0.8.0;

/**
 * @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");
        require(isContract(target), "Address: call to non-contract");

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

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
        return functionStaticCall(target, data, "Address: low-level static call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data, string memory errorMessage) internal view returns (bytes memory) {
        require(isContract(target), "Address: static call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.staticcall(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionDelegateCall(target, data, "Address: low-level delegate call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(address target, bytes memory data, string memory errorMessage) internal returns (bytes memory) {
        require(isContract(target), "Address: delegate call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.delegatecall(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    function _verifyCallResult(bool success, bytes memory returndata, string memory errorMessage) private pure returns(bytes memory) {
        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: @uniswap/v3-core/contracts/interfaces/pool/IUniswapV3PoolImmutables.sol



// SPDX-License-Identifier: GPL-2.0-or-later
pragma solidity >=0.5.0;

/// @title Pool state that never changes
/// @notice These parameters are fixed for a pool forever, i.e., the methods will always return the same values
interface IUniswapV3PoolImmutables {
    /// @notice The contract that deployed the pool, which must adhere to the IUniswapV3Factory interface
    /// @return The contract address
    function factory() external view returns (address);

    /// @notice The first of the two tokens of the pool, sorted by address
    /// @return The token contract address
    function token0() external view returns (address);

    /// @notice The second of the two tokens of the pool, sorted by address
    /// @return The token contract address
    function token1() external view returns (address);

    /// @notice The pool's fee in hundredths of a bip, i.e. 1e-6
    /// @return The fee
    function fee() external view returns (uint24);

    /// @notice The pool tick spacing
    /// @dev Ticks can only be used at multiples of this value, minimum of 1 and always positive
    /// e.g.: a tickSpacing of 3 means ticks can be initialized every 3rd tick, i.e., ..., -6, -3, 0, 3, 6, ...
    /// This value is an int24 to avoid casting even though it is always positive.
    /// @return The tick spacing
    function tickSpacing() external view returns (int24);

    /// @notice The maximum amount of position liquidity that can use any tick in the range
    /// @dev This parameter is enforced per tick to prevent liquidity from overflowing a uint128 at any point, and
    /// also prevents out-of-range liquidity from being used to prevent adding in-range liquidity to a pool
    /// @return The max amount of liquidity per tick
    function maxLiquidityPerTick() external view returns (uint128);
}

// File: @uniswap/v3-core/contracts/interfaces/pool/IUniswapV3PoolState.sol



// SPDX-License-Identifier: GPL-2.0-or-later
pragma solidity >=0.5.0;

/// @title Pool state that can change
/// @notice These methods compose the pool's state, and can change with any frequency including multiple times
/// per transaction
interface IUniswapV3PoolState {
    /// @notice The 0th storage slot in the pool stores many values, and is exposed as a single method to save gas
    /// when accessed externally.
    /// @return sqrtPriceX96 The current price of the pool as a sqrt(token1/token0) Q64.96 value
    /// tick The current tick of the pool, i.e. according to the last tick transition that was run.
    /// This value may not always be equal to SqrtTickMath.getTickAtSqrtRatio(sqrtPriceX96) if the price is on a tick
    /// boundary.
    /// observationIndex The index of the last oracle observation that was written,
    /// observationCardinality The current maximum number of observations stored in the pool,
    /// observationCardinalityNext The next maximum number of observations, to be updated when the observation.
    /// feeProtocol The protocol fee for both tokens of the pool.
    /// Encoded as two 4 bit values, where the protocol fee of token1 is shifted 4 bits and the protocol fee of token0
    /// is the lower 4 bits. Used as the denominator of a fraction of the swap fee, e.g. 4 means 1/4th of the swap fee.
    /// unlocked Whether the pool is currently locked to reentrancy
    function slot0()
        external
        view
        returns (
            uint160 sqrtPriceX96,
            int24 tick,
            uint16 observationIndex,
            uint16 observationCardinality,
            uint16 observationCardinalityNext,
            uint8 feeProtocol,
            bool unlocked
        );

    /// @notice The fee growth as a Q128.128 fees of token0 collected per unit of liquidity for the entire life of the pool
    /// @dev This value can overflow the uint256
    function feeGrowthGlobal0X128() external view returns (uint256);

    /// @notice The fee growth as a Q128.128 fees of token1 collected per unit of liquidity for the entire life of the pool
    /// @dev This value can overflow the uint256
    function feeGrowthGlobal1X128() external view returns (uint256);

    /// @notice The amounts of token0 and token1 that are owed to the protocol
    /// @dev Protocol fees will never exceed uint128 max in either token
    function protocolFees() external view returns (uint128 token0, uint128 token1);

    /// @notice The currently in range liquidity available to the pool
    /// @dev This value has no relationship to the total liquidity across all ticks
    function liquidity() external view returns (uint128);

    /// @notice Look up information about a specific tick in the pool
    /// @param tick The tick to look up
    /// @return liquidityGross the total amount of position liquidity that uses the pool either as tick lower or
    /// tick upper,
    /// liquidityNet how much liquidity changes when the pool price crosses the tick,
    /// feeGrowthOutside0X128 the fee growth on the other side of the tick from the current tick in token0,
    /// feeGrowthOutside1X128 the fee growth on the other side of the tick from the current tick in token1,
    /// tickCumulativeOutside the cumulative tick value on the other side of the tick from the current tick
    /// secondsPerLiquidityOutsideX128 the seconds spent per liquidity on the other side of the tick from the current tick,
    /// secondsOutside the seconds spent on the other side of the tick from the current tick,
    /// initialized Set to true if the tick is initialized, i.e. liquidityGross is greater than 0, otherwise equal to false.
    /// Outside values can only be used if the tick is initialized, i.e. if liquidityGross is greater than 0.
    /// In addition, these values are only relative and must be used only in comparison to previous snapshots for
    /// a specific position.
    function ticks(int24 tick)
        external
        view
        returns (
            uint128 liquidityGross,
            int128 liquidityNet,
            uint256 feeGrowthOutside0X128,
            uint256 feeGrowthOutside1X128,
            int56 tickCumulativeOutside,
            uint160 secondsPerLiquidityOutsideX128,
            uint32 secondsOutside,
            bool initialized
        );

    /// @notice Returns 256 packed tick initialized boolean values. See TickBitmap for more information
    function tickBitmap(int16 wordPosition) external view returns (uint256);

    /// @notice Returns the information about a position by the position's key
    /// @param key The position's key is a hash of a preimage composed by the owner, tickLower and tickUpper
    /// @return _liquidity The amount of liquidity in the position,
    /// Returns feeGrowthInside0LastX128 fee growth of token0 inside the tick range as of the last mint/burn/poke,
    /// Returns feeGrowthInside1LastX128 fee growth of token1 inside the tick range as of the last mint/burn/poke,
    /// Returns tokensOwed0 the computed amount of token0 owed to the position as of the last mint/burn/poke,
    /// Returns tokensOwed1 the computed amount of token1 owed to the position as of the last mint/burn/poke
    function positions(bytes32 key)
        external
        view
        returns (
            uint128 _liquidity,
            uint256 feeGrowthInside0LastX128,
            uint256 feeGrowthInside1LastX128,
            uint128 tokensOwed0,
            uint128 tokensOwed1
        );

    /// @notice Returns data about a specific observation index
    /// @param index The element of the observations array to fetch
    /// @dev You most likely want to use #observe() instead of this method to get an observation as of some amount of time
    /// ago, rather than at a specific index in the array.
    /// @return blockTimestamp The timestamp of the observation,
    /// Returns tickCumulative the tick multiplied by seconds elapsed for the life of the pool as of the observation timestamp,
    /// Returns secondsPerLiquidityCumulativeX128 the seconds per in range liquidity for the life of the pool as of the observation timestamp,
    /// Returns initialized whether the observation has been initialized and the values are safe to use
    function observations(uint256 index)
        external
        view
        returns (
            uint32 blockTimestamp,
            int56 tickCumulative,
            uint160 secondsPerLiquidityCumulativeX128,
            bool initialized
        );
}

// File: @uniswap/v3-core/contracts/interfaces/pool/IUniswapV3PoolDerivedState.sol



// SPDX-License-Identifier: GPL-2.0-or-later
pragma solidity >=0.5.0;

/// @title Pool state that is not stored
/// @notice Contains view functions to provide information about the pool that is computed rather than stored on the
/// blockchain. The functions here may have variable gas costs.
interface IUniswapV3PoolDerivedState {
    /// @notice Returns the cumulative tick and liquidity as of each timestamp `secondsAgo` from the current block timestamp
    /// @dev To get a time weighted average tick or liquidity-in-range, you must call this with two values, one representing
    /// the beginning of the period and another for the end of the period. E.g., to get the last hour time-weighted average tick,
    /// you must call it with secondsAgos = [3600, 0].
    /// @dev The time weighted average tick represents the geometric time weighted average price of the pool, in
    /// log base sqrt(1.0001) of token1 / token0. The TickMath library can be used to go from a tick value to a ratio.
    /// @param secondsAgos From how long ago each cumulative tick and liquidity value should be returned
    /// @return tickCumulatives Cumulative tick values as of each `secondsAgos` from the current block timestamp
    /// @return secondsPerLiquidityCumulativeX128s Cumulative seconds per liquidity-in-range value as of each `secondsAgos` from the current block
    /// timestamp
    function observe(uint32[] calldata secondsAgos)
        external
        view
        returns (int56[] memory tickCumulatives, uint160[] memory secondsPerLiquidityCumulativeX128s);

    /// @notice Returns a snapshot of the tick cumulative, seconds per liquidity and seconds inside a tick range
    /// @dev Snapshots must only be compared to other snapshots, taken over a period for which a position existed.
    /// I.e., snapshots cannot be compared if a position is not held for the entire period between when the first
    /// snapshot is taken and the second snapshot is taken.
    /// @param tickLower The lower tick of the range
    /// @param tickUpper The upper tick of the range
    /// @return tickCumulativeInside The snapshot of the tick accumulator for the range
    /// @return secondsPerLiquidityInsideX128 The snapshot of seconds per liquidity for the range
    /// @return secondsInside The snapshot of seconds per liquidity for the range
    function snapshotCumulativesInside(int24 tickLower, int24 tickUpper)
        external
        view
        returns (
            int56 tickCumulativeInside,
            uint160 secondsPerLiquidityInsideX128,
            uint32 secondsInside
        );
}

// File: @uniswap/v3-core/contracts/interfaces/pool/IUniswapV3PoolActions.sol



// SPDX-License-Identifier: GPL-2.0-or-later
pragma solidity >=0.5.0;

/// @title Permissionless pool actions
/// @notice Contains pool methods that can be called by anyone
interface IUniswapV3PoolActions {
    /// @notice Sets the initial price for the pool
    /// @dev Price is represented as a sqrt(amountToken1/amountToken0) Q64.96 value
    /// @param sqrtPriceX96 the initial sqrt price of the pool as a Q64.96
    function initialize(uint160 sqrtPriceX96) external;

    /// @notice Adds liquidity for the given recipient/tickLower/tickUpper position
    /// @dev The caller of this method receives a callback in the form of IUniswapV3MintCallback#uniswapV3MintCallback
    /// in which they must pay any token0 or token1 owed for the liquidity. The amount of token0/token1 due depends
    /// on tickLower, tickUpper, the amount of liquidity, and the current price.
    /// @param recipient The address for which the liquidity will be created
    /// @param tickLower The lower tick of the position in which to add liquidity
    /// @param tickUpper The upper tick of the position in which to add liquidity
    /// @param amount The amount of liquidity to mint
    /// @param data Any data that should be passed through to the callback
    /// @return amount0 The amount of token0 that was paid to mint the given amount of liquidity. Matches the value in the callback
    /// @return amount1 The amount of token1 that was paid to mint the given amount of liquidity. Matches the value in the callback
    function mint(
        address recipient,
        int24 tickLower,
        int24 tickUpper,
        uint128 amount,
        bytes calldata data
    ) external returns (uint256 amount0, uint256 amount1);

    /// @notice Collects tokens owed to a position
    /// @dev Does not recompute fees earned, which must be done either via mint or burn of any amount of liquidity.
    /// Collect must be called by the position owner. To withdraw only token0 or only token1, amount0Requested or
    /// amount1Requested may be set to zero. To withdraw all tokens owed, caller may pass any value greater than the
    /// actual tokens owed, e.g. type(uint128).max. Tokens owed may be from accumulated swap fees or burned liquidity.
    /// @param recipient The address which should receive the fees collected
    /// @param tickLower The lower tick of the position for which to collect fees
    /// @param tickUpper The upper tick of the position for which to collect fees
    /// @param amount0Requested How much token0 should be withdrawn from the fees owed
    /// @param amount1Requested How much token1 should be withdrawn from the fees owed
    /// @return amount0 The amount of fees collected in token0
    /// @return amount1 The amount of fees collected in token1
    function collect(
        address recipient,
        int24 tickLower,
        int24 tickUpper,
        uint128 amount0Requested,
        uint128 amount1Requested
    ) external returns (uint128 amount0, uint128 amount1);

    /// @notice Burn liquidity from the sender and account tokens owed for the liquidity to the position
    /// @dev Can be used to trigger a recalculation of fees owed to a position by calling with an amount of 0
    /// @dev Fees must be collected separately via a call to #collect
    /// @param tickLower The lower tick of the position for which to burn liquidity
    /// @param tickUpper The upper tick of the position for which to burn liquidity
    /// @param amount How much liquidity to burn
    /// @return amount0 The amount of token0 sent to the recipient
    /// @return amount1 The amount of token1 sent to the recipient
    function burn(
        int24 tickLower,
        int24 tickUpper,
        uint128 amount
    ) external returns (uint256 amount0, uint256 amount1);

    /// @notice Swap token0 for token1, or token1 for token0
    /// @dev The caller of this method receives a callback in the form of IUniswapV3SwapCallback#uniswapV3SwapCallback
    /// @param recipient The address to receive the output of the swap
    /// @param zeroForOne The direction of the swap, true for token0 to token1, false for token1 to token0
    /// @param amountSpecified The amount of the swap, which implicitly configures the swap as exact input (positive), or exact output (negative)
    /// @param sqrtPriceLimitX96 The Q64.96 sqrt price limit. If zero for one, the price cannot be less than this
    /// value after the swap. If one for zero, the price cannot be greater than this value after the swap
    /// @param data Any data to be passed through to the callback
    /// @return amount0 The delta of the balance of token0 of the pool, exact when negative, minimum when positive
    /// @return amount1 The delta of the balance of token1 of the pool, exact when negative, minimum when positive
    function swap(
        address recipient,
        bool zeroForOne,
        int256 amountSpecified,
        uint160 sqrtPriceLimitX96,
        bytes calldata data
    ) external returns (int256 amount0, int256 amount1);

    /// @notice Receive token0 and/or token1 and pay it back, plus a fee, in the callback
    /// @dev The caller of this method receives a callback in the form of IUniswapV3FlashCallback#uniswapV3FlashCallback
    /// @dev Can be used to donate underlying tokens pro-rata to currently in-range liquidity providers by calling
    /// with 0 amount{0,1} and sending the donation amount(s) from the callback
    /// @param recipient The address which will receive the token0 and token1 amounts
    /// @param amount0 The amount of token0 to send
    /// @param amount1 The amount of token1 to send
    /// @param data Any data to be passed through to the callback
    function flash(
        address recipient,
        uint256 amount0,
        uint256 amount1,
        bytes calldata data
    ) external;

    /// @notice Increase the maximum number of price and liquidity observations that this pool will store
    /// @dev This method is no-op if the pool already has an observationCardinalityNext greater than or equal to
    /// the input observationCardinalityNext.
    /// @param observationCardinalityNext The desired minimum number of observations for the pool to store
    function increaseObservationCardinalityNext(uint16 observationCardinalityNext) external;
}

// File: @uniswap/v3-core/contracts/interfaces/pool/IUniswapV3PoolOwnerActions.sol



// SPDX-License-Identifier: GPL-2.0-or-later
pragma solidity >=0.5.0;

/// @title Permissioned pool actions
/// @notice Contains pool methods that may only be called by the factory owner
interface IUniswapV3PoolOwnerActions {
    /// @notice Set the denominator of the protocol's % share of the fees
    /// @param feeProtocol0 new protocol fee for token0 of the pool
    /// @param feeProtocol1 new protocol fee for token1 of the pool
    function setFeeProtocol(uint8 feeProtocol0, uint8 feeProtocol1) external;

    /// @notice Collect the protocol fee accrued to the pool
    /// @param recipient The address to which collected protocol fees should be sent
    /// @param amount0Requested The maximum amount of token0 to send, can be 0 to collect fees in only token1
    /// @param amount1Requested The maximum amount of token1 to send, can be 0 to collect fees in only token0
    /// @return amount0 The protocol fee collected in token0
    /// @return amount1 The protocol fee collected in token1
    function collectProtocol(
        address recipient,
        uint128 amount0Requested,
        uint128 amount1Requested
    ) external returns (uint128 amount0, uint128 amount1);
}

// File: @uniswap/v3-core/contracts/interfaces/pool/IUniswapV3PoolEvents.sol



// SPDX-License-Identifier: GPL-2.0-or-later
pragma solidity >=0.5.0;

/// @title Events emitted by a pool
/// @notice Contains all events emitted by the pool
interface IUniswapV3PoolEvents {
    /// @notice Emitted exactly once by a pool when #initialize is first called on the pool
    /// @dev Mint/Burn/Swap cannot be emitted by the pool before Initialize
    /// @param sqrtPriceX96 The initial sqrt price of the pool, as a Q64.96
    /// @param tick The initial tick of the pool, i.e. log base 1.0001 of the starting price of the pool
    event Initialize(uint160 sqrtPriceX96, int24 tick);

    /// @notice Emitted when liquidity is minted for a given position
    /// @param sender The address that minted the liquidity
    /// @param owner The owner of the position and recipient of any minted liquidity
    /// @param tickLower The lower tick of the position
    /// @param tickUpper The upper tick of the position
    /// @param amount The amount of liquidity minted to the position range
    /// @param amount0 How much token0 was required for the minted liquidity
    /// @param amount1 How much token1 was required for the minted liquidity
    event Mint(
        address sender,
        address indexed owner,
        int24 indexed tickLower,
        int24 indexed tickUpper,
        uint128 amount,
        uint256 amount0,
        uint256 amount1
    );

    /// @notice Emitted when fees are collected by the owner of a position
    /// @dev Collect events may be emitted with zero amount0 and amount1 when the caller chooses not to collect fees
    /// @param owner The owner of the position for which fees are collected
    /// @param tickLower The lower tick of the position
    /// @param tickUpper The upper tick of the position
    /// @param amount0 The amount of token0 fees collected
    /// @param amount1 The amount of token1 fees collected
    event Collect(
        address indexed owner,
        address recipient,
        int24 indexed tickLower,
        int24 indexed tickUpper,
        uint128 amount0,
        uint128 amount1
    );

    /// @notice Emitted when a position's liquidity is removed
    /// @dev Does not withdraw any fees earned by the liquidity position, which must be withdrawn via #collect
    /// @param owner The owner of the position for which liquidity is removed
    /// @param tickLower The lower tick of the position
    /// @param tickUpper The upper tick of the position
    /// @param amount The amount of liquidity to remove
    /// @param amount0 The amount of token0 withdrawn
    /// @param amount1 The amount of token1 withdrawn
    event Burn(
        address indexed owner,
        int24 indexed tickLower,
        int24 indexed tickUpper,
        uint128 amount,
        uint256 amount0,
        uint256 amount1
    );

    /// @notice Emitted by the pool for any swaps between token0 and token1
    /// @param sender The address that initiated the swap call, and that received the callback
    /// @param recipient The address that received the output of the swap
    /// @param amount0 The delta of the token0 balance of the pool
    /// @param amount1 The delta of the token1 balance of the pool
    /// @param sqrtPriceX96 The sqrt(price) of the pool after the swap, as a Q64.96
    /// @param liquidity The liquidity of the pool after the swap
    /// @param tick The log base 1.0001 of price of the pool after the swap
    event Swap(
        address indexed sender,
        address indexed recipient,
        int256 amount0,
        int256 amount1,
        uint160 sqrtPriceX96,
        uint128 liquidity,
        int24 tick
    );

    /// @notice Emitted by the pool for any flashes of token0/token1
    /// @param sender The address that initiated the swap call, and that received the callback
    /// @param recipient The address that received the tokens from flash
    /// @param amount0 The amount of token0 that was flashed
    /// @param amount1 The amount of token1 that was flashed
    /// @param paid0 The amount of token0 paid for the flash, which can exceed the amount0 plus the fee
    /// @param paid1 The amount of token1 paid for the flash, which can exceed the amount1 plus the fee
    event Flash(
        address indexed sender,
        address indexed recipient,
        uint256 amount0,
        uint256 amount1,
        uint256 paid0,
        uint256 paid1
    );

    /// @notice Emitted by the pool for increases to the number of observations that can be stored
    /// @dev observationCardinalityNext is not the observation cardinality until an observation is written at the index
    /// just before a mint/swap/burn.
    /// @param observationCardinalityNextOld The previous value of the next observation cardinality
    /// @param observationCardinalityNextNew The updated value of the next observation cardinality
    event IncreaseObservationCardinalityNext(
        uint16 observationCardinalityNextOld,
        uint16 observationCardinalityNextNew
    );

    /// @notice Emitted when the protocol fee is changed by the pool
    /// @param feeProtocol0Old The previous value of the token0 protocol fee
    /// @param feeProtocol1Old The previous value of the token1 protocol fee
    /// @param feeProtocol0New The updated value of the token0 protocol fee
    /// @param feeProtocol1New The updated value of the token1 protocol fee
    event SetFeeProtocol(uint8 feeProtocol0Old, uint8 feeProtocol1Old, uint8 feeProtocol0New, uint8 feeProtocol1New);

    /// @notice Emitted when the collected protocol fees are withdrawn by the factory owner
    /// @param sender The address that collects the protocol fees
    /// @param recipient The address that receives the collected protocol fees
    /// @param amount0 The amount of token0 protocol fees that is withdrawn
    /// @param amount0 The amount of token1 protocol fees that is withdrawn
    event CollectProtocol(address indexed sender, address indexed recipient, uint128 amount0, uint128 amount1);
}

// File: @openzeppelin/contracts/token/ERC721/IERC721.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.2 <0.8.0;

import "../../introspection/IERC165.sol";

/**
 * @dev Required interface of an ERC721 compliant contract.
 */
interface IERC721 is IERC165 {
    /**
     * @dev Emitted when `tokenId` token is transferred from `from` to `to`.
     */
    event Transfer(address indexed from, address indexed to, uint256 indexed tokenId);

    /**
     * @dev Emitted when `owner` enables `approved` to manage the `tokenId` token.
     */
    event Approval(address indexed owner, address indexed approved, uint256 indexed tokenId);

    /**
     * @dev Emitted when `owner` enables or disables (`approved`) `operator` to manage all of its assets.
     */
    event ApprovalForAll(address indexed owner, address indexed operator, bool approved);

    /**
     * @dev Returns the number of tokens in ``owner``'s account.
     */
    function balanceOf(address owner) external view returns (uint256 balance);

    /**
     * @dev Returns the owner of the `tokenId` token.
     *
     * Requirements:
     *
     * - `tokenId` must exist.
     */
    function ownerOf(uint256 tokenId) external view returns (address owner);

    /**
     * @dev Safely transfers `tokenId` token from `from` to `to`, checking first that contract recipients
     * are aware of the ERC721 protocol to prevent tokens from being forever locked.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `tokenId` token must exist and be owned by `from`.
     * - If the caller is not `from`, it must be have been allowed to move this token by either {approve} or {setApprovalForAll}.
     * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
     *
     * Emits a {Transfer} event.
     */
    function safeTransferFrom(address from, address to, uint256 tokenId) external;

    /**
     * @dev Transfers `tokenId` token from `from` to `to`.
     *
     * WARNING: Usage of this method is discouraged, use {safeTransferFrom} whenever possible.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `tokenId` token must be owned by `from`.
     * - If the caller is not `from`, it must be approved to move this token by either {approve} or {setApprovalForAll}.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(address from, address to, uint256 tokenId) external;

    /**
     * @dev Gives permission to `to` to transfer `tokenId` token to another account.
     * The approval is cleared when the token is transferred.
     *
     * Only a single account can be approved at a time, so approving the zero address clears previous approvals.
     *
     * Requirements:
     *
     * - The caller must own the token or be an approved operator.
     * - `tokenId` must exist.
     *
     * Emits an {Approval} event.
     */
    function approve(address to, uint256 tokenId) external;

    /**
     * @dev Returns the account approved for `tokenId` token.
     *
     * Requirements:
     *
     * - `tokenId` must exist.
     */
    function getApproved(uint256 tokenId) external view returns (address operator);

    /**
     * @dev Approve or remove `operator` as an operator for the caller.
     * Operators can call {transferFrom} or {safeTransferFrom} for any token owned by the caller.
     *
     * Requirements:
     *
     * - The `operator` cannot be the caller.
     *
     * Emits an {ApprovalForAll} event.
     */
    function setApprovalForAll(address operator, bool _approved) external;

    /**
     * @dev Returns if the `operator` is allowed to manage all of the assets of `owner`.
     *
     * See {setApprovalForAll}
     */
    function isApprovedForAll(address owner, address operator) external view returns (bool);

    /**
      * @dev Safely transfers `tokenId` token from `from` to `to`.
      *
      * Requirements:
      *
      * - `from` cannot be the zero address.
      * - `to` cannot be the zero address.
      * - `tokenId` token must exist and be owned by `from`.
      * - If the caller is not `from`, it must be approved to move this token by either {approve} or {setApprovalForAll}.
      * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
      *
      * Emits a {Transfer} event.
      */
    function safeTransferFrom(address from, address to, uint256 tokenId, bytes calldata data) external;
}

// File: @openzeppelin/contracts/token/ERC721/IERC721Receiver.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

/**
 * @title ERC721 token receiver interface
 * @dev Interface for any contract that wants to support safeTransfers
 * from ERC721 asset contracts.
 */
interface IERC721Receiver {
    /**
     * @dev Whenever an {IERC721} `tokenId` token is transferred to this contract via {IERC721-safeTransferFrom}
     * by `operator` from `from`, this function is called.
     *
     * It must return its Solidity selector to confirm the token transfer.
     * If any other value is returned or the interface is not implemented by the recipient, the transfer will be reverted.
     *
     * The selector can be obtained in Solidity with `IERC721.onERC721Received.selector`.
     */
    function onERC721Received(address operator, address from, uint256 tokenId, bytes calldata data) external returns (bytes4);
}

// File: @openzeppelin/contracts/proxy/Initializable.sol



// SPDX-License-Identifier: MIT

// solhint-disable-next-line compiler-version
pragma solidity >=0.4.24 <0.8.0;

import "../utils/Address.sol";

/**
 * @dev This is a base contract to aid in writing upgradeable contracts, or any kind of contract that will be deployed
 * behind a proxy. Since a proxied contract can't have a constructor, it's common to move constructor logic to an
 * external initializer function, usually called `initialize`. It then becomes necessary to protect this initializer
 * function so it can only be called once. The {initializer} modifier provided by this contract will have this effect.
 *
 * TIP: To avoid leaving the proxy in an uninitialized state, the initializer function should be called as early as
 * possible by providing the encoded function call as the `_data` argument to {UpgradeableProxy-constructor}.
 *
 * CAUTION: When used with inheritance, manual care must be taken to not invoke a parent initializer twice, or to ensure
 * that all initializers are idempotent. This is not verified automatically as constructors are by Solidity.
 */
abstract contract Initializable {

    /**
     * @dev Indicates that the contract has been initialized.
     */
    bool private _initialized;

    /**
     * @dev Indicates that the contract is in the process of being initialized.
     */
    bool private _initializing;

    /**
     * @dev Modifier to protect an initializer function from being invoked twice.
     */
    modifier initializer() {
        require(_initializing || _isConstructor() || !_initialized, "Initializable: contract is already initialized");

        bool isTopLevelCall = !_initializing;
        if (isTopLevelCall) {
            _initializing = true;
            _initialized = true;
        }

        _;

        if (isTopLevelCall) {
            _initializing = false;
        }
    }

    /// @dev Returns true if and only if the function is running in the constructor
    function _isConstructor() private view returns (bool) {
        return !Address.isContract(address(this));
    }
}

// File: @openzeppelin/contracts/utils/EnumerableSet.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

/**
 * @dev Library for managing
 * https://en.wikipedia.org/wiki/Set_(abstract_data_type)[sets] of primitive
 * types.
 *
 * Sets have the following properties:
 *
 * - Elements are added, removed, and checked for existence in constant time
 * (O(1)).
 * - Elements are enumerated in O(n). No guarantees are made on the ordering.
 *
 * ```
 * contract Example {
 *     // Add the library methods
 *     using EnumerableSet for EnumerableSet.AddressSet;
 *
 *     // Declare a set state variable
 *     EnumerableSet.AddressSet private mySet;
 * }
 * ```
 *
 * As of v3.3.0, sets of type `bytes32` (`Bytes32Set`), `address` (`AddressSet`)
 * and `uint256` (`UintSet`) are supported.
 */
library EnumerableSet {
    // To implement this library for multiple types with as little code
    // repetition as possible, we write it in terms of a generic Set type with
    // bytes32 values.
    // The Set implementation uses private functions, and user-facing
    // implementations (such as AddressSet) are just wrappers around the
    // underlying Set.
    // This means that we can only create new EnumerableSets for types that fit
    // in bytes32.

    struct Set {
        // Storage of set values
        bytes32[] _values;

        // Position of the value in the `values` array, plus 1 because index 0
        // means a value is not in the set.
        mapping (bytes32 => uint256) _indexes;
    }

    /**
     * @dev Add a value to a set. O(1).
     *
     * Returns true if the value was added to the set, that is if it was not
     * already present.
     */
    function _add(Set storage set, bytes32 value) private returns (bool) {
        if (!_contains(set, value)) {
            set._values.push(value);
            // The value is stored at length-1, but we add 1 to all indexes
            // and use 0 as a sentinel value
            set._indexes[value] = set._values.length;
            return true;
        } else {
            return false;
        }
    }

    /**
     * @dev Removes a value from a set. O(1).
     *
     * Returns true if the value was removed from the set, that is if it was
     * present.
     */
    function _remove(Set storage set, bytes32 value) private returns (bool) {
        // We read and store the value's index to prevent multiple reads from the same storage slot
        uint256 valueIndex = set._indexes[value];

        if (valueIndex != 0) { // Equivalent to contains(set, value)
            // To delete an element from the _values array in O(1), we swap the element to delete with the last one in
            // the array, and then remove the last element (sometimes called as 'swap and pop').
            // This modifies the order of the array, as noted in {at}.

            uint256 toDeleteIndex = valueIndex - 1;
            uint256 lastIndex = set._values.length - 1;

            // When the value to delete is the last one, the swap operation is unnecessary. However, since this occurs
            // so rarely, we still do the swap anyway to avoid the gas cost of adding an 'if' statement.

            bytes32 lastvalue = set._values[lastIndex];

            // Move the last value to the index where the value to delete is
            set._values[toDeleteIndex] = lastvalue;
            // Update the index for the moved value
            set._indexes[lastvalue] = toDeleteIndex + 1; // All indexes are 1-based

            // Delete the slot where the moved value was stored
            set._values.pop();

            // Delete the index for the deleted slot
            delete set._indexes[value];

            return true;
        } else {
            return false;
        }
    }

    /**
     * @dev Returns true if the value is in the set. O(1).
     */
    function _contains(Set storage set, bytes32 value) private view returns (bool) {
        return set._indexes[value] != 0;
    }

    /**
     * @dev Returns the number of values on the set. O(1).
     */
    function _length(Set storage set) private view returns (uint256) {
        return set._values.length;
    }

   /**
    * @dev Returns the value stored at position `index` in the set. O(1).
    *
    * Note that there are no guarantees on the ordering of values inside the
    * array, and it may change when more values are added or removed.
    *
    * Requirements:
    *
    * - `index` must be strictly less than {length}.
    */
    function _at(Set storage set, uint256 index) private view returns (bytes32) {
        require(set._values.length > index, "EnumerableSet: index out of bounds");
        return set._values[index];
    }

    // Bytes32Set

    struct Bytes32Set {
        Set _inner;
    }

    /**
     * @dev Add a value to a set. O(1).
     *
     * Returns true if the value was added to the set, that is if it was not
     * already present.
     */
    function add(Bytes32Set storage set, bytes32 value) internal returns (bool) {
        return _add(set._inner, value);
    }

    /**
     * @dev Removes a value from a set. O(1).
     *
     * Returns true if the value was removed from the set, that is if it was
     * present.
     */
    function remove(Bytes32Set storage set, bytes32 value) internal returns (bool) {
        return _remove(set._inner, value);
    }

    /**
     * @dev Returns true if the value is in the set. O(1).
     */
    function contains(Bytes32Set storage set, bytes32 value) internal view returns (bool) {
        return _contains(set._inner, value);
    }

    /**
     * @dev Returns the number of values in the set. O(1).
     */
    function length(Bytes32Set storage set) internal view returns (uint256) {
        return _length(set._inner);
    }

   /**
    * @dev Returns the value stored at position `index` in the set. O(1).
    *
    * Note that there are no guarantees on the ordering of values inside the
    * array, and it may change when more values are added or removed.
    *
    * Requirements:
    *
    * - `index` must be strictly less than {length}.
    */
    function at(Bytes32Set storage set, uint256 index) internal view returns (bytes32) {
        return _at(set._inner, index);
    }

    // AddressSet

    struct AddressSet {
        Set _inner;
    }

    /**
     * @dev Add a value to a set. O(1).
     *
     * Returns true if the value was added to the set, that is if it was not
     * already present.
     */
    function add(AddressSet storage set, address value) internal returns (bool) {
        return _add(set._inner, bytes32(uint256(uint160(value))));
    }

    /**
     * @dev Removes a value from a set. O(1).
     *
     * Returns true if the value was removed from the set, that is if it was
     * present.
     */
    function remove(AddressSet storage set, address value) internal returns (bool) {
        return _remove(set._inner, bytes32(uint256(uint160(value))));
    }

    /**
     * @dev Returns true if the value is in the set. O(1).
     */
    function contains(AddressSet storage set, address value) internal view returns (bool) {
        return _contains(set._inner, bytes32(uint256(uint160(value))));
    }

    /**
     * @dev Returns the number of values in the set. O(1).
     */
    function length(AddressSet storage set) internal view returns (uint256) {
        return _length(set._inner);
    }

   /**
    * @dev Returns the value stored at position `index` in the set. O(1).
    *
    * Note that there are no guarantees on the ordering of values inside the
    * array, and it may change when more values are added or removed.
    *
    * Requirements:
    *
    * - `index` must be strictly less than {length}.
    */
    function at(AddressSet storage set, uint256 index) internal view returns (address) {
        return address(uint160(uint256(_at(set._inner, index))));
    }


    // UintSet

    struct UintSet {
        Set _inner;
    }

    /**
     * @dev Add a value to a set. O(1).
     *
     * Returns true if the value was added to the set, that is if it was not
     * already present.
     */
    function add(UintSet storage set, uint256 value) internal returns (bool) {
        return _add(set._inner, bytes32(value));
    }

    /**
     * @dev Removes a value from a set. O(1).
     *
     * Returns true if the value was removed from the set, that is if it was
     * present.
     */
    function remove(UintSet storage set, uint256 value) internal returns (bool) {
        return _remove(set._inner, bytes32(value));
    }

    /**
     * @dev Returns true if the value is in the set. O(1).
     */
    function contains(UintSet storage set, uint256 value) internal view returns (bool) {
        return _contains(set._inner, bytes32(value));
    }

    /**
     * @dev Returns the number of values on the set. O(1).
     */
    function length(UintSet storage set) internal view returns (uint256) {
        return _length(set._inner);
    }

   /**
    * @dev Returns the value stored at position `index` in the set. O(1).
    *
    * Note that there are no guarantees on the ordering of values inside the
    * array, and it may change when more values are added or removed.
    *
    * Requirements:
    *
    * - `index` must be strictly less than {length}.
    */
    function at(UintSet storage set, uint256 index) internal view returns (uint256) {
        return uint256(_at(set._inner, index));
    }
}

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



// SPDX-License-Identifier: GPL-3.0-or-later

pragma solidity >=0.6.0;

// helper methods for interacting with ERC20 tokens and sending ETH that do not consistently return true/false
library TransferHelper {
    function safeApprove(
        address token,
        address to,
        uint256 value
    ) internal {
        // bytes4(keccak256(bytes('approve(address,uint256)')));
        (bool success, bytes memory data) = token.call(abi.encodeWithSelector(0x095ea7b3, to, value));
        require(
            success && (data.length == 0 || abi.decode(data, (bool))),
            'TransferHelper::safeApprove: approve failed'
        );
    }

    function safeTransfer(
        address token,
        address to,
        uint256 value
    ) internal {
        // bytes4(keccak256(bytes('transfer(address,uint256)')));
        (bool success, bytes memory data) = token.call(abi.encodeWithSelector(0xa9059cbb, to, value));
        require(
            success && (data.length == 0 || abi.decode(data, (bool))),
            'TransferHelper::safeTransfer: transfer failed'
        );
    }

    function safeTransferFrom(
        address token,
        address from,
        address to,
        uint256 value
    ) internal {
        // bytes4(keccak256(bytes('transferFrom(address,address,uint256)')));
        (bool success, bytes memory data) = token.call(abi.encodeWithSelector(0x23b872dd, from, to, value));
        require(
            success && (data.length == 0 || abi.decode(data, (bool))),
            'TransferHelper::transferFrom: transferFrom failed'
        );
    }

    function safeTransferETH(address to, uint256 value) internal {
        (bool success, ) = to.call{value: value}(new bytes(0));
        require(success, 'TransferHelper::safeTransferETH: ETH transfer failed');
    }
}

// File: contracts/visor/EIP712.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

/* solhint-disable max-line-length */

/**
 * @dev https://eips.ethereum.org/EIPS/eip-712[EIP 712] is a standard for hashing and signing of typed structured data.
 *
 * The encoding specified in the EIP is very generic, and such a generic implementation in Solidity is not feasible,
 * thus this contract does not implement the encoding itself. Protocols need to implement the type-specific encoding
 * they need in their contracts using a combination of `abi.encode` and `keccak256`.
 *
 * This contract implements the EIP 712 domain separator ({_domainSeparatorV4}) that is used as part of the encoding
 * scheme, and the final step of the encoding to obtain the message digest that is then signed via ECDSA
 * ({_hashTypedDataV4}).
 *
 * The implementation of the domain separator was designed to be as efficient as possible while still properly updating
 * the chain id to protect against replay attacks on an eventual fork of the chain.
 *
 * NOTE: This contract implements the version of the encoding known as "v4", as implemented by the JSON RPC method
 * https://docs.metamask.io/guide/signing-data.html[`eth_signTypedDataV4` in MetaMask].
 *
 * _Available since v3.4._
 */
abstract contract EIP712 {
    /* solhint-disable var-name-mixedcase */
    bytes32 private immutable _HASHED_NAME;
    bytes32 private immutable _HASHED_VERSION;
    bytes32 private constant _TYPE_HASH =
        keccak256(
            "EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)"
        );

    /* solhint-enable var-name-mixedcase */

    /**
     * @dev Initializes the domain separator and parameter caches.
     *
     * The meaning of `name` and `version` is specified in
     * https://eips.ethereum.org/EIPS/eip-712#definition-of-domainseparator[EIP 712]:
     *
     * - `name`: the user readable name of the signing domain, i.e. the name of the DApp or the protocol.
     * - `version`: the current major version of the signing domain.
     *
     * NOTE: These parameters cannot be changed except through a xref:learn::upgrading-smart-contracts.adoc[smart
     * contract upgrade].
     */

    constructor(string memory name, string memory version) {
        _HASHED_NAME = keccak256(bytes(name));
        _HASHED_VERSION = keccak256(bytes(version));
    }

    /**
     * @dev Returns the domain separator for the current chain.
     */
    function _domainSeparatorV4() internal view returns (bytes32) {
        return _buildDomainSeparator(_TYPE_HASH, _EIP712NameHash(), _EIP712VersionHash());
    }

    function _buildDomainSeparator(
        bytes32 typeHash,
        bytes32 name,
        bytes32 version
    ) private view returns (bytes32) {
        return keccak256(abi.encode(typeHash, name, version, _getChainId(), address(this)));
    }

    /**
     * @dev Given an already https://eips.ethereum.org/EIPS/eip-712#definition-of-hashstruct[hashed struct], this
     * function returns the hash of the fully encoded EIP712 message for this domain.
     *
     * This hash can be used together with {ECDSA-recover} to obtain the signer of a message. For example:
     *
     * ```solidity
     * bytes32 digest = _hashTypedDataV4(keccak256(abi.encode(
     *     keccak256("Mail(address to,string contents)"),
     *     mailTo,
     *     keccak256(bytes(mailContents))
     * )));
     * address signer = ECDSA.recover(digest, signature);
     * ```
     */
    function _hashTypedDataV4(bytes32 structHash) internal view virtual returns (bytes32) {
        return keccak256(abi.encodePacked("\x19\x01", _domainSeparatorV4(), structHash));
    }

    function _getChainId() private view returns (uint256 chainId) {
        this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
        // solhint-disable-next-line no-inline-assembly
        assembly {
            chainId := chainid()
        }
    }

    /**
     * @dev The hash of the name parameter for the EIP712 domain.
     *
     * NOTE: This function reads from storage by default, but can be redefined to return a constant value if gas costs
     * are a concern.
     */
    function _EIP712NameHash() internal view virtual returns (bytes32) {
        return _HASHED_NAME;
    }

    /**
     * @dev The hash of the version parameter for the EIP712 domain.
     *
     * NOTE: This function reads from storage by default, but can be redefined to return a constant value if gas costs
     * are a concern.
     */
    function _EIP712VersionHash() internal view virtual returns (bytes32) {
        return _HASHED_VERSION;
    }
}

// File: contracts/visor/ERC1271.sol



// SPDX-License-Identifier: GPL-3.0-only
pragma solidity 0.7.6;

import {ECDSA} from "@openzeppelin/contracts/cryptography/ECDSA.sol";
import {Address} from "@openzeppelin/contracts/utils/Address.sol";

interface IERC1271 {
    function isValidSignature(bytes32 _messageHash, bytes memory _signature)
        external
        view
        returns (bytes4 magicValue);
}

library SignatureChecker {
    function isValidSignature(
        address signer,
        bytes32 hash,
        bytes memory signature
    ) internal view returns (bool) {
        if (Address.isContract(signer)) {
            bytes4 selector = IERC1271.isValidSignature.selector;
            (bool success, bytes memory returndata) =
                signer.staticcall(abi.encodeWithSelector(selector, hash, signature));
            return success && abi.decode(returndata, (bytes4)) == selector;
        } else {
            return ECDSA.recover(hash, signature) == signer;
        }
    }
}

/// @title ERC1271
/// @notice Module for ERC1271 compatibility
abstract contract ERC1271 is IERC1271 {
    // Valid magic value bytes4(keccak256("isValidSignature(bytes32,bytes)")
    bytes4 internal constant VALID_SIG = IERC1271.isValidSignature.selector;
    // Invalid magic value
    bytes4 internal constant INVALID_SIG = bytes4(0);

    modifier onlyValidSignature(bytes32 permissionHash, bytes memory signature) {
        require(
            isValidSignature(permissionHash, signature) == VALID_SIG,
            "ERC1271: Invalid signature"
        );
        _;
    }

    function _getOwner() internal view virtual returns (address owner);

    function isValidSignature(bytes32 permissionHash, bytes memory signature)
        public
        view
        override
        returns (bytes4)
    {
        return
            SignatureChecker.isValidSignature(_getOwner(), permissionHash, signature)
                ? VALID_SIG
                : INVALID_SIG;
    }
}

// File: contracts/visor/OwnableERC721.sol



// SPDX-License-Identifier: GPL-3.0-only
pragma solidity 0.7.6;

import {IERC721} from "@openzeppelin/contracts/token/ERC721/IERC721.sol";

/// @title OwnableERC721
/// @notice Use ERC721 ownership for access control
contract OwnableERC721 {
    address private _nftAddress;

    modifier onlyOwner() {
        require(owner() == msg.sender, "OwnableERC721: caller is not the owner");
        _;
    }

    function _setNFT(address nftAddress) internal {
        _nftAddress = nftAddress;
    }

    function nft() public view virtual returns (address nftAddress) {
        return _nftAddress;
    }

    function owner() public view virtual returns (address ownerAddress) {
        return IERC721(_nftAddress).ownerOf(uint256(address(this)));
    }
}

// File: contracts/hypervisor/Hypervisor.sol



// SPDX-License-Identifier: GPL-3.0-only
pragma solidity 0.7.6;
pragma abicoder v2;

import {SafeMath} from "@openzeppelin/contracts/math/SafeMath.sol";
import {EnumerableSet} from "@openzeppelin/contracts/utils/EnumerableSet.sol";
import {IERC20} from "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import {Ownable} from "@openzeppelin/contracts/access/Ownable.sol";
import {TransferHelper} from "@uniswap/lib/contracts/libraries/TransferHelper.sol";

import {IFactory} from "../factory/IFactory.sol";
import {IInstanceRegistry} from "../factory/InstanceRegistry.sol";
import {IUniversalVault} from "../interfaces/IUniversalVault.sol";
import {IRewardPool} from "./RewardPool.sol";
import {Powered} from "./Powered.sol";

interface IRageQuit {
    function rageQuit() external;
}

interface IHypervisor is IRageQuit {
    /* admin events */

    event HypervisorCreated(address rewardPool, address powerSwitch);
    event HypervisorFunded(uint256 amount, uint256 duration);
    event BonusTokenRegistered(address token);
    event VaultFactoryRegistered(address factory);
    event VaultFactoryRemoved(address factory);

    /* user events */

    event Staked(address vault, uint256 amount);
    event Unstaked(address vault, uint256 amount);
    event RewardClaimed(address vault, address recipient, address token, uint256 amount);

    /* data types */

    struct HypervisorData {
        address stakingToken;
        address rewardToken;
        address rewardPool;
        RewardScaling rewardScaling;
        uint256 rewardSharesOutstanding;
        uint256 totalStake;
        uint256 totalStakeUnits;
        uint256 lastUpdate;
        RewardSchedule[] rewardSchedules;
    }

    struct RewardSchedule {
        uint256 duration;
        uint256 start;
        uint256 shares;
    }

    struct VaultData {
        uint256 totalStake;
        StakeData[] stakes;
    }

    struct StakeData {
        uint256 amount;
        uint256 timestamp;
    }

    struct RewardScaling {
        uint256 floor;
        uint256 ceiling;
        uint256 time;
    }

    struct RewardOutput {
        uint256 lastStakeAmount;
        uint256 newStakesCount;
        uint256 reward;
        uint256 newTotalStakeUnits;
    }

    /* user functions */

    function stake(
        address vault,
        uint256 amount,
        bytes calldata permission
    ) external;

    function unstakeAndClaim(
        address vault,
        uint256 amount,
        bytes calldata permission
    ) external;

    /* getter functions */

    function getHypervisorData() external view returns (HypervisorData memory hypervisor);

    function getBonusTokenSetLength() external view returns (uint256 length);

    function getBonusTokenAtIndex(uint256 index) external view returns (address bonusToken);

    function getVaultFactorySetLength() external view returns (uint256 length);

    function getVaultFactoryAtIndex(uint256 index) external view returns (address factory);

    function getVaultData(address vault) external view returns (VaultData memory vaultData);

    function isValidAddress(address target) external view returns (bool validity);

    function isValidVault(address target) external view returns (bool validity);

    function getCurrentUnlockedRewards() external view returns (uint256 unlockedRewards);

    function getFutureUnlockedRewards(uint256 timestamp)
        external
        view
        returns (uint256 unlockedRewards);

    function getCurrentVaultReward(address vault) external view returns (uint256 reward);

    function getCurrentStakeReward(address vault, uint256 stakeAmount)
        external
        view
        returns (uint256 reward);

    function getFutureVaultReward(address vault, uint256 timestamp)
        external
        view
        returns (uint256 reward);

    function getFutureStakeReward(
        address vault,
        uint256 stakeAmount,
        uint256 timestamp
    ) external view returns (uint256 reward);

    function getCurrentVaultStakeUnits(address vault) external view returns (uint256 stakeUnits);

    function getFutureVaultStakeUnits(address vault, uint256 timestamp)
        external
        view
        returns (uint256 stakeUnits);

    function getCurrentTotalStakeUnits() external view returns (uint256 totalStakeUnits);

    function getFutureTotalStakeUnits(uint256 timestamp)
        external
        view
        returns (uint256 totalStakeUnits);

    /* pure functions */

    function calculateTotalStakeUnits(StakeData[] memory stakes, uint256 timestamp)
        external
        pure
        returns (uint256 totalStakeUnits);

    function calculateStakeUnits(
        uint256 amount,
        uint256 start,
        uint256 end
    ) external pure returns (uint256 stakeUnits);

    function calculateUnlockedRewards(
        RewardSchedule[] memory rewardSchedules,
        uint256 rewardBalance,
        uint256 sharesOutstanding,
        uint256 timestamp
    ) external pure returns (uint256 unlockedRewards);

    function calculateRewardFromStakes(
        StakeData[] memory stakes,
        uint256 unstakeAmount,
        uint256 unlockedRewards,
        uint256 totalStakeUnits,
        uint256 timestamp,
        RewardScaling memory rewardScaling
    ) external pure returns (RewardOutput memory out);

    function calculateReward(
        uint256 unlockedRewards,
        uint256 stakeAmount,
        uint256 stakeDuration,
        uint256 totalStakeUnits,
        RewardScaling memory rewardScaling
    ) external pure returns (uint256 reward);
}

/// @title Hypervisor
/// @notice Reward distribution contract with time multiplier
/// Access Control
/// - Power controller:
///     Can power off / shutdown the Hypervisor
///     Can withdraw rewards from reward pool once shutdown
/// - Proxy owner:
///     Can change arbitrary logic / state by upgrading the Hypervisor
///     Is unable to operate on user funds due to UniversalVault
///     Is unable to operate on reward pool funds when reward pool is offline / shutdown
/// - Hypervisor admin:
///     Can add funds to the Hypervisor, register bonus tokens, and whitelist new vault factories
///     Is a subset of proxy owner permissions
/// - User:
///     Can deposit / withdraw / ragequit
/// Hypervisor State Machine
/// - Online:
///     Hypervisor is operating normally, all functions are enabled
/// - Offline:
///     Hypervisor is temporarely disabled for maintenance
///     User deposits and withdrawls are disabled, ragequit remains enabled
///     Users can withdraw their stake through rageQuit() but forego their pending reward
///     Should only be used when downtime required for an upgrade
/// - Shutdown:
///     Hypervisor is permanently disabled
///     All functions are disabled with the exception of ragequit
///     Users can withdraw their stake through rageQuit()
///     Power controller can withdraw from the reward pool
///     Should only be used if Proxy Owner role is compromized
contract Hypervisor is IHypervisor, Powered, Ownable {
    using SafeMath for uint256;
    using EnumerableSet for EnumerableSet.AddressSet;

    /* constants */

    // An upper bound on the number of active stakes per vault is required to prevent
    // calls to rageQuit() from reverting.
    // With 30 stakes in a vault, ragequit costs 432811 gas which is conservatively lower
    // than the hardcoded limit of 500k gas on the vault.
    // This limit is configurable and could be increased in a future deployment.
    // Ultimately, to avoid a need for fixed upper bounds, the EVM would need to provide
    // an error code that allows for reliably catching out-of-gas errors on remote calls.
    uint256 public constant MAX_STAKES_PER_VAULT = 30;
    uint256 public constant MAX_REWARD_TOKENS = 50;
    uint256 public constant BASE_SHARES_PER_WEI = 1000000;
    uint256 public stakeLimit = 2500 ether;

    /* storage */

    HypervisorData private _hypervisor;
    mapping(address => VaultData) private _vaults;
    EnumerableSet.AddressSet private _bonusTokenSet;
    EnumerableSet.AddressSet private _vaultFactorySet;

    /* initializer */

    /// @notice Initizalize Hypervisor
    /// access control: only proxy constructor
    /// state machine: can only be called once
    /// state scope: set initialization variables
    /// token transfer: none
    /// @param ownerAddress address The admin address
    /// @param rewardPoolFactory address The factory to use for deploying the RewardPool
    /// @param powerSwitchFactory address The factory to use for deploying the PowerSwitch
    /// @param stakingToken address The address of the staking token for this Hypervisor
    /// @param rewardToken address The address of the reward token for this Hypervisor
    /// @param rewardScaling RewardScaling The config for reward scaling floor, ceiling, and time
    constructor(
        address ownerAddress,
        address rewardPoolFactory,
        address powerSwitchFactory,
        address stakingToken,
        address rewardToken,
        RewardScaling memory rewardScaling,
        uint256 _stakeLimit
    ) {
        // the scaling floor must be smaller than ceiling
        require(rewardScaling.floor <= rewardScaling.ceiling, "Hypervisor: floor above ceiling");

        // setting rewardScalingTime to 0 would cause divide by zero error
        // to disable reward scaling, use rewardScalingFloor == rewardScalingCeiling
        require(rewardScaling.time != 0, "Hypervisor: scaling time cannot be zero");

        // deploy power switch
        address powerSwitch = IFactory(powerSwitchFactory).create(abi.encode(ownerAddress));

        // deploy reward pool
        address rewardPool = IFactory(rewardPoolFactory).create(abi.encode(powerSwitch));

        // set internal configs
        Ownable.transferOwnership(ownerAddress);
        Powered._setPowerSwitch(powerSwitch);

        // commit to storage
        _hypervisor.stakingToken = stakingToken;
        _hypervisor.rewardToken = rewardToken;
        _hypervisor.rewardPool = rewardPool;
        _hypervisor.rewardScaling = rewardScaling;

        stakeLimit = _stakeLimit;

        // emit event
        emit HypervisorCreated(rewardPool, powerSwitch);
    }

    /* getter functions */

    function getBonusTokenSetLength() external view override returns (uint256 length) {
        return _bonusTokenSet.length();
    }

    function getBonusTokenAtIndex(uint256 index)
        external
        view
        override
        returns (address bonusToken)
    {
        return _bonusTokenSet.at(index);
    }

    function getVaultFactorySetLength() external view override returns (uint256 length) {
        return _vaultFactorySet.length();
    }

    function getVaultFactoryAtIndex(uint256 index)
        external
        view
        override
        returns (address factory)
    {
        return _vaultFactorySet.at(index);
    }

    function isValidVault(address target) public view override returns (bool validity) {
        // validate target is created from whitelisted vault factory
        for (uint256 index = 0; index < _vaultFactorySet.length(); index++) {
            if (IInstanceRegistry(_vaultFactorySet.at(index)).isInstance(target)) {
                return true;
            }
        }
        // explicit return
        return false;
    }

    function isValidAddress(address target) public view override returns (bool validity) {
        // sanity check target for potential input errors
        return
            target != address(this) &&
            target != address(0) &&
            target != _hypervisor.stakingToken &&
            target != _hypervisor.rewardToken &&
            target != _hypervisor.rewardPool &&
            !_bonusTokenSet.contains(target);
    }

    /* Hypervisor getters */

    function getHypervisorData() external view override returns (HypervisorData memory hypervisor) {
        return _hypervisor;
    }

    function getCurrentUnlockedRewards() public view override returns (uint256 unlockedRewards) {
        // calculate reward available based on state
        return getFutureUnlockedRewards(block.timestamp);
    }

    function getFutureUnlockedRewards(uint256 timestamp)
        public
        view
        override
        returns (uint256 unlockedRewards)
    {
        // get reward amount remaining
        uint256 remainingRewards = IERC20(_hypervisor.rewardToken).balanceOf(_hypervisor.rewardPool);
        // calculate reward available based on state
        unlockedRewards = calculateUnlockedRewards(
            _hypervisor.rewardSchedules,
            remainingRewards,
            _hypervisor.rewardSharesOutstanding,
            timestamp
        );
        // explicit return
        return unlockedRewards;
    }

    function getCurrentTotalStakeUnits() public view override returns (uint256 totalStakeUnits) {
        // calculate new stake units
        return getFutureTotalStakeUnits(block.timestamp);
    }

    function getFutureTotalStakeUnits(uint256 timestamp)
        public
        view
        override
        returns (uint256 totalStakeUnits)
    {
        // return early if no change
        if (timestamp == _hypervisor.lastUpdate) return _hypervisor.totalStakeUnits;
        // calculate new stake units
        uint256 newStakeUnits =
            calculateStakeUnits(_hypervisor.totalStake, _hypervisor.lastUpdate, timestamp);
        // add to cached total
        totalStakeUnits = _hypervisor.totalStakeUnits.add(newStakeUnits);
        // explicit return
        return totalStakeUnits;
    }

    /* vault getters */

    function getVaultData(address vault)
        external
        view
        override
        returns (VaultData memory vaultData)
    {
        return _vaults[vault];
    }

    function getCurrentVaultReward(address vault) external view override returns (uint256 reward) {
        // calculate rewards
        return
            calculateRewardFromStakes(
                _vaults[vault]
                    .stakes,
                _vaults[vault]
                    .totalStake,
                getCurrentUnlockedRewards(),
                getCurrentTotalStakeUnits(),
                block
                    .timestamp,
                _hypervisor
                    .rewardScaling
            )
                .reward;
    }

    function getFutureVaultReward(address vault, uint256 timestamp)
        external
        view
        override
        returns (uint256 reward)
    {
        // calculate rewards
        return
            calculateRewardFromStakes(
                _vaults[vault]
                    .stakes,
                _vaults[vault]
                    .totalStake,
                getFutureUnlockedRewards(timestamp),
                getFutureTotalStakeUnits(timestamp),
                timestamp,
                _hypervisor
                    .rewardScaling
            )
                .reward;
    }

    function getCurrentStakeReward(address vault, uint256 stakeAmount)
        external
        view
        override
        returns (uint256 reward)
    {
        // calculate rewards
        return
            calculateRewardFromStakes(
                _vaults[vault]
                    .stakes,
                stakeAmount,
                getCurrentUnlockedRewards(),
                getCurrentTotalStakeUnits(),
                block
                    .timestamp,
                _hypervisor
                    .rewardScaling
            )
                .reward;
    }

    function getFutureStakeReward(
        address vault,
        uint256 stakeAmount,
        uint256 timestamp
    ) external view override returns (uint256 reward) {
        // calculate rewards
        return
            calculateRewardFromStakes(
                _vaults[vault]
                    .stakes,
                stakeAmount,
                getFutureUnlockedRewards(timestamp),
                getFutureTotalStakeUnits(timestamp),
                timestamp,
                _hypervisor
                    .rewardScaling
            )
                .reward;
    }

    function getCurrentVaultStakeUnits(address vault)
        public
        view
        override
        returns (uint256 stakeUnits)
    {
        // calculate stake units
        return getFutureVaultStakeUnits(vault, block.timestamp);
    }

    function getFutureVaultStakeUnits(address vault, uint256 timestamp)
        public
        view
        override
        returns (uint256 stakeUnits)
    {
        // calculate stake units
        return calculateTotalStakeUnits(_vaults[vault].stakes, timestamp);
    }

    /* pure functions */

    function calculateTotalStakeUnits(StakeData[] memory stakes, uint256 timestamp)
        public
        pure
        override
        returns (uint256 totalStakeUnits)
    {
        for (uint256 index; index < stakes.length; index++) {
            // reference stake
            StakeData memory stakeData = stakes[index];
            // calculate stake units
            uint256 stakeUnits =
                calculateStakeUnits(stakeData.amount, stakeData.timestamp, timestamp);
            // add to running total
            totalStakeUnits = totalStakeUnits.add(stakeUnits);
        }
    }

    function calculateStakeUnits(
        uint256 amount,
        uint256 start,
        uint256 end
    ) public pure override returns (uint256 stakeUnits) {
        // calculate duration
        uint256 duration = end.sub(start);
        // calculate stake units
        stakeUnits = duration.mul(amount);
        // explicit return
        return stakeUnits;
    }

    function calculateUnlockedRewards(
        RewardSchedule[] memory rewardSchedules,
        uint256 rewardBalance,
        uint256 sharesOutstanding,
        uint256 timestamp
    ) public pure override returns (uint256 unlockedRewards) {
        // return 0 if no registered schedules
        if (rewardSchedules.length == 0) {
            return 0;
        }

        // calculate reward shares locked across all reward schedules
        uint256 sharesLocked;
        for (uint256 index = 0; index < rewardSchedules.length; index++) {
            // fetch reward schedule storage reference
            RewardSchedule memory schedule = rewardSchedules[index];

            // caculate amount of shares available on this schedule
            // if (now - start) < duration
            //   sharesLocked = shares - (shares * (now - start) / duration)
            // else
            //   sharesLocked = 0
            uint256 currentSharesLocked = 0;
            if (timestamp.sub(schedule.start) < schedule.duration) {
                currentSharesLocked = schedule.shares.sub(
                    schedule.shares.mul(timestamp.sub(schedule.start)).div(schedule.duration)
                );
            }

            // add to running total
            sharesLocked = sharesLocked.add(currentSharesLocked);
        }

        // convert shares to reward
        // rewardLocked = sharesLocked * rewardBalance / sharesOutstanding
        uint256 rewardLocked = sharesLocked.mul(rewardBalance).div(sharesOutstanding);

        // calculate amount available
        // unlockedRewards = rewardBalance - rewardLocked
        unlockedRewards = rewardBalance.sub(rewardLocked);

        // explicit return
        return unlockedRewards;
    }

    function calculateRewardFromStakes(
        StakeData[] memory stakes,
        uint256 unstakeAmount,
        uint256 unlockedRewards,
        uint256 totalStakeUnits,
        uint256 timestamp,
        RewardScaling memory rewardScaling
    ) public pure override returns (RewardOutput memory out) {
        uint256 stakesToDrop = 0;
        while (unstakeAmount > 0) {
            // fetch vault stake storage reference
            StakeData memory lastStake = stakes[stakes.length.sub(stakesToDrop).sub(1)];

            // calculate stake duration
            uint256 stakeDuration = timestamp.sub(lastStake.timestamp);

            uint256 currentAmount;
            if (lastStake.amount > unstakeAmount) {
                // set current amount to remaining unstake amount
                currentAmount = unstakeAmount;
                // amount of last stake is reduced
                out.lastStakeAmount = lastStake.amount.sub(unstakeAmount);
            } else {
                // set current amount to amount of last stake
                currentAmount = lastStake.amount;
                // add to stakes to drop
                stakesToDrop += 1;
            }

            // update remaining unstakeAmount
            unstakeAmount = unstakeAmount.sub(currentAmount);

            // calculate reward amount
            uint256 currentReward =
                calculateReward(
                    unlockedRewards,
                    currentAmount,
                    stakeDuration,
                    totalStakeUnits,
                    rewardScaling
                );

            // update cumulative reward
            out.reward = out.reward.add(currentReward);

            // update cached unlockedRewards
            unlockedRewards = unlockedRewards.sub(currentReward);

            // calculate time weighted stake
            uint256 stakeUnits = currentAmount.mul(stakeDuration);

            // update cached totalStakeUnits
            totalStakeUnits = totalStakeUnits.sub(stakeUnits);
        }

        // explicit return
        return
            RewardOutput(
                out.lastStakeAmount,
                stakes.length.sub(stakesToDrop),
                out.reward,
                totalStakeUnits
            );
    }

    function calculateReward(
        uint256 unlockedRewards,
        uint256 stakeAmount,
        uint256 stakeDuration,
        uint256 totalStakeUnits,
        RewardScaling memory rewardScaling
    ) public pure override returns (uint256 reward) {
        // calculate time weighted stake
        uint256 stakeUnits = stakeAmount.mul(stakeDuration);

        // calculate base reward
        // baseReward = unlockedRewards * stakeUnits / totalStakeUnits
        uint256 baseReward = 0;
        if (totalStakeUnits != 0) {
            // scale reward according to proportional weight
            baseReward = unlockedRewards.mul(stakeUnits).div(totalStakeUnits);
        }

        // calculate scaled reward
        // if no scaling or scaling period completed
        //   reward = baseReward
        // else
        //   minReward = baseReward * scalingFloor / scalingCeiling
        //   bonusReward = baseReward
        //                 * (scalingCeiling - scalingFloor) / scalingCeiling
        //                 * duration / scalingTime
        //   reward = minReward + bonusReward
        if (stakeDuration >= rewardScaling.time || rewardScaling.floor == rewardScaling.ceiling) {
            // no reward scaling applied
            reward = baseReward;
        } else {
            // calculate minimum reward using scaling floor
            uint256 minReward = baseReward.mul(rewardScaling.floor).div(rewardScaling.ceiling);

            // calculate bonus reward with vested portion of scaling factor
            uint256 bonusReward =
                baseReward
                    .mul(stakeDuration)
                    .mul(rewardScaling.ceiling.sub(rewardScaling.floor))
                    .div(rewardScaling.ceiling)
                    .div(rewardScaling.time);

            // add minimum reward and bonus reward
            reward = minReward.add(bonusReward);
        }

        // explicit return
        return reward;
    }

    /* admin functions */

    /// @notice Add funds to the Hypervisor
    /// access control: only admin
    /// state machine:
    ///   - can be called multiple times
    ///   - only online
    /// state scope:
    ///   - increase _hypervisor.rewardSharesOutstanding
    ///   - append to _hypervisor.rewardSchedules
    /// token transfer: transfer staking tokens from msg.sender to reward pool
    /// @param amount uint256 Amount of reward tokens to deposit
    /// @param duration uint256 Duration over which to linearly unlock rewards
    function fund(uint256 amount, uint256 duration) external onlyOwner onlyOnline {
        // validate duration
        require(duration != 0, "Hypervisor: invalid duration");

        // create new reward shares
        // if existing rewards on this Hypervisor
        //   mint new shares proportional to % change in rewards remaining
        //   newShares = remainingShares * newReward / remainingRewards
        // else
        //   mint new shares with BASE_SHARES_PER_WEI initial conversion rate
        //   store as fixed point number with same  of decimals as reward token
        uint256 newRewardShares;
        if (_hypervisor.rewardSharesOutstanding > 0) {
            uint256 remainingRewards = IERC20(_hypervisor.rewardToken).balanceOf(_hypervisor.rewardPool);
            newRewardShares = _hypervisor.rewardSharesOutstanding.mul(amount).div(remainingRewards);
        } else {
            newRewardShares = amount.mul(BASE_SHARES_PER_WEI);
        }

        // add reward shares to total
        _hypervisor.rewardSharesOutstanding = _hypervisor.rewardSharesOutstanding.add(newRewardShares);

        // store new reward schedule
        _hypervisor.rewardSchedules.push(RewardSchedule(duration, block.timestamp, newRewardShares));

        // transfer reward tokens to reward pool
        TransferHelper.safeTransferFrom(
            _hypervisor.rewardToken,
            msg.sender,
            _hypervisor.rewardPool,
            amount
        );

        // emit event
        emit HypervisorFunded(amount, duration);
    }

    /// @notice Add vault factory to whitelist
    /// @dev use this function to enable stakes to vaults coming from the specified
    ///      factory contract
    /// access control: only admin
    /// state machine:
    ///   - can be called multiple times
    ///   - not shutdown
    /// state scope:
    ///   - append to _vaultFactorySet
    /// token transfer: none
    /// @param factory address The address of the vault factory
    function registerVaultFactory(address factory) external onlyOwner notShutdown {
        // add factory to set
        require(_vaultFactorySet.add(factory), "Hypervisor: vault factory already registered");

        // emit event
        emit VaultFactoryRegistered(factory);
    }

    /// @notice Remove vault factory from whitelist
    /// @dev use this function to disable new stakes to vaults coming from the specified
    ///      factory contract.
    ///      note: vaults with existing stakes from this factory are sill able to unstake
    /// access control: only admin
    /// state machine:
    ///   - can be called multiple times
    ///   - not shutdown
    /// state scope:
    ///   - remove from _vaultFactorySet
    /// token transfer: none
    /// @param factory address The address of the vault factory
    function removeVaultFactory(address factory) external onlyOwner notShutdown {
        // remove factory from set
        require(_vaultFactorySet.remove(factory), "Hypervisor: vault factory not registered");

        // emit event
        emit VaultFactoryRemoved(factory);
    }

    /// @notice Register bonus token for distribution
    /// @dev use this function to enable distribution of any ERC20 held by the RewardPool contract
    /// access control: only admin
    /// state machine:
    ///   - can be called multiple times
    ///   - only online
    /// state scope:
    ///   - append to _bonusTokenSet
    /// token transfer: none
    /// @param bonusToken address The address of the bonus token
    function registerBonusToken(address bonusToken) external onlyOwner onlyOnline {
        // verify valid bonus token
        _validateAddress(bonusToken);

        // verify bonus token count
        require(_bonusTokenSet.length() < MAX_REWARD_TOKENS, "Hypervisor: max bonus tokens reached ");

        // add token to set
        assert(_bonusTokenSet.add(bonusToken));

        // emit event
        emit BonusTokenRegistered(bonusToken);
    }

    /// @notice Rescue tokens from RewardPool
    /// @dev use this function to rescue tokens from RewardPool contract
    ///      without distributing to stakers or triggering emergency shutdown
    /// access control: only admin
    /// state machine:
    ///   - can be called multiple times
    ///   - only online
    /// state scope: none
    /// token transfer: transfer requested token from RewardPool to recipient
    /// @param token address The address of the token to rescue
    /// @param recipient address The address of the recipient
    /// @param amount uint256 The amount of tokens to rescue
    function rescueTokensFromRewardPool(
        address token,
        address recipient,
        uint256 amount
    ) external onlyOwner onlyOnline {
        // verify recipient
        _validateAddress(recipient);

        // check not attempting to unstake reward token
        require(token != _hypervisor.rewardToken, "Hypervisor: invalid address");

        // check not attempting to wthdraw bonus token
        require(!_bonusTokenSet.contains(token), "Hypervisor: invalid address");

        // transfer tokens to recipient
        IRewardPool(_hypervisor.rewardPool).sendERC20(token, recipient, amount);
    }

    /* user functions */

    /// @notice Stake tokens
    /// @dev anyone can stake to any vault if they have valid permission
    /// access control: anyone
    /// state machine:
    ///   - can be called multiple times
    ///   - only online
    ///   - when vault exists on this Hypervisor
    /// state scope:
    ///   - append to _vaults[vault].stakes
    ///   - increase _vaults[vault].totalStake
    ///   - increase _hypervisor.totalStake
    ///   - increase _hypervisor.totalStakeUnits
    ///   - increase _hypervisor.lastUpdate
    /// token transfer: transfer staking tokens from msg.sender to vault
    /// @param vault address The address of the vault to stake from
    /// @param amount uint256 The amount of staking tokens to stake
    function stake(
        address vault,
        uint256 amount,
        bytes calldata permission
    ) external override onlyOnline {
        // verify vault is valid
        require(isValidVault(vault), "Hypervisor: vault is not registered");

        // verify non-zero amount
        require(amount != 0, "Hypervisor: no amount staked");

        // fetch vault storage reference
        VaultData storage vaultData = _vaults[vault];

        // verify stakes boundary not reached
        require(
            vaultData.stakes.length < MAX_STAKES_PER_VAULT,
            "Hypervisor: MAX_STAKES_PER_VAULT reached"
        );

        // update cached sum of stake units across all vaults
        _updateTotalStakeUnits();

        // store amount and timestamp
        vaultData.stakes.push(StakeData(amount, block.timestamp));

        // update cached total vault and Hypervisor amounts
        vaultData.totalStake = vaultData.totalStake.add(amount);
        // verify stake quantity without bounds
        require(
            stakeLimit == 0 || vaultData.totalStake <= stakeLimit,
            "Hypervisor: Stake limit exceeded"
        );
        _hypervisor.totalStake = _hypervisor.totalStake.add(amount);

        // call lock on vault
        IUniversalVault(vault).lock(_hypervisor.stakingToken, amount, permission);

        // emit event
        emit Staked(vault, amount);
    }

    /// @notice Unstake staking tokens and claim reward
    /// @dev rewards can only be claimed when unstaking
    /// access control: only owner of vault
    /// state machine:
    ///   - when vault exists on this Hypervisor
    ///   - after stake from vault
    ///   - can be called multiple times while sufficient stake remains
    ///   - only online
    /// state scope:
    ///   - decrease _hypervisor.rewardSharesOutstanding
    ///   - decrease _hypervisor.totalStake
    ///   - increase _hypervisor.lastUpdate
    ///   - modify _hypervisor.totalStakeUnits
    ///   - modify _vaults[vault].stakes
    ///   - decrease _vaults[vault].totalStake
    /// token transfer:
    ///   - transfer reward tokens from reward pool to recipient
    ///   - transfer bonus tokens from reward pool to recipient
    /// @param vault address The vault to unstake from
    /// @param amount uint256 The amount of staking tokens to unstake
    function unstakeAndClaim(
        address vault,
        uint256 amount,
        bytes calldata permission
    ) external override onlyOnline {
        // fetch vault storage reference
        VaultData storage vaultData = _vaults[vault];

        // verify non-zero amount
        require(amount != 0, "Hypervisor: no amount unstaked");

        address recipient = IUniversalVault(vault).owner();

        // validate recipient
        _validateAddress(recipient);

        // check for sufficient vault stake amount
        require(vaultData.totalStake >= amount, "Hypervisor: insufficient vault stake");

        // check for sufficient Hypervisor stake amount
        // if this check fails, there is a bug in stake accounting
        assert(_hypervisor.totalStake >= amount);

        // update cached sum of stake units across all vaults
        _updateTotalStakeUnits();

        // get reward amount remaining
        uint256 remainingRewards = IERC20(_hypervisor.rewardToken).balanceOf(_hypervisor.rewardPool);

        // calculate vested portion of reward pool
        uint256 unlockedRewards =
            calculateUnlockedRewards(
                _hypervisor.rewardSchedules,
                remainingRewards,
                _hypervisor.rewardSharesOutstanding,
                block.timestamp
            );

        // calculate vault time weighted reward with scaling
        RewardOutput memory out =
            calculateRewardFromStakes(
                vaultData.stakes,
                amount,
                unlockedRewards,
                _hypervisor.totalStakeUnits,
                block.timestamp,
                _hypervisor.rewardScaling
            );

        // update stake data in storage
        if (out.newStakesCount == 0) {
            // all stakes have been unstaked
            delete vaultData.stakes;
        } else {
            // some stakes have been completely or partially unstaked
            // delete fully unstaked stakes
            while (vaultData.stakes.length > out.newStakesCount) vaultData.stakes.pop();
            // update partially unstaked stake
            vaultData.stakes[out.newStakesCount.sub(1)].amount = out.lastStakeAmount;
        }

        // update cached stake totals
        vaultData.totalStake = vaultData.totalStake.sub(amount);
        _hypervisor.totalStake = _hypervisor.totalStake.sub(amount);
        _hypervisor.totalStakeUnits = out.newTotalStakeUnits;

        // unlock staking tokens from vault
        IUniversalVault(vault).unlock(_hypervisor.stakingToken, amount, permission);

        // emit event
        emit Unstaked(vault, amount);

        // only perform on non-zero reward
        if (out.reward > 0) {
            // calculate shares to burn
            // sharesToBurn = sharesOutstanding * reward / remainingRewards
            uint256 sharesToBurn =
                _hypervisor.rewardSharesOutstanding.mul(out.reward).div(remainingRewards);

            // burn claimed shares
            _hypervisor.rewardSharesOutstanding = _hypervisor.rewardSharesOutstanding.sub(sharesToBurn);

            // transfer bonus tokens from reward pool to recipient
            if (_bonusTokenSet.length() > 0) {
                for (uint256 index = 0; index < _bonusTokenSet.length(); index++) {
                    // fetch bonus token address reference
                    address bonusToken = _bonusTokenSet.at(index);

                    // calculate bonus token amount
                    // bonusAmount = bonusRemaining * reward / remainingRewards
                    uint256 bonusAmount =
                        IERC20(bonusToken).balanceOf(_hypervisor.rewardPool).mul(out.reward).div(
                            remainingRewards
                        );

                    // transfer bonus token
                    IRewardPool(_hypervisor.rewardPool).sendERC20(bonusToken, recipient, bonusAmount);

                    // emit event
                    emit RewardClaimed(vault, recipient, bonusToken, bonusAmount);
                }
            }

            // transfer reward tokens from reward pool to recipient
            IRewardPool(_hypervisor.rewardPool).sendERC20(_hypervisor.rewardToken, recipient, out.reward);

            // emit event
            emit RewardClaimed(vault, recipient, _hypervisor.rewardToken, out.reward);
        }
    }

    /// @notice Exit Hypervisor without claiming reward
    /// @dev This function should never revert when correctly called by the vault.
    ///      A max number of stakes per vault is set with MAX_STAKES_PER_VAULT to
    ///      place an upper bound on the for loop in calculateTotalStakeUnits().
    /// access control: only callable by the vault directly
    /// state machine:
    ///   - when vault exists on this Hypervisor
    ///   - when active stake from this vault
    ///   - any power state
    /// state scope:
    ///   - decrease _hypervisor.totalStake
    ///   - increase _hypervisor.lastUpdate
    ///   - modify _hypervisor.totalStakeUnits
    ///   - delete _vaults[vault]
    /// token transfer: none
    function rageQuit() external override {
        // fetch vault storage reference
        VaultData storage _vaultData = _vaults[msg.sender];

        // revert if no active stakes
        require(_vaultData.stakes.length != 0, "Hypervisor: no stake");

        // update cached sum of stake units across all vaults
        _updateTotalStakeUnits();

        // emit event
        emit Unstaked(msg.sender, _vaultData.totalStake);

        // update cached totals
        _hypervisor.totalStake = _hypervisor.totalStake.sub(_vaultData.totalStake);
        _hypervisor.totalStakeUnits = _hypervisor.totalStakeUnits.sub(
            calculateTotalStakeUnits(_vaultData.stakes, block.timestamp)
        );

        // delete stake data
        delete _vaults[msg.sender];
    }

    /* convenience functions */

    function _updateTotalStakeUnits() private {
        // update cached totalStakeUnits
        _hypervisor.totalStakeUnits = getCurrentTotalStakeUnits();
        // update cached lastUpdate
        _hypervisor.lastUpdate = block.timestamp;
    }

    function _validateAddress(address target) private view {
        // sanity check target for potential input errors
        require(isValidAddress(target), "Hypervisor: invalid address");
    }

    function _truncateStakesArray(StakeData[] memory array, uint256 newLength)
        private
        pure
        returns (StakeData[] memory newArray)
    {
        newArray = new StakeData[](newLength);
        for (uint256 index = 0; index < newLength; index++) {
            newArray[index] = array[index];
        }
        return newArray;
    }
}

// File: contracts/interfaces/IUniversalVault.sol



// SPDX-License-Identifier: GPL-3.0-only
pragma solidity 0.7.6;
pragma abicoder v2;

interface IUniversalVault {
    /* user events */

    event Locked(address delegate, address token, uint256 amount);
    event Unlocked(address delegate, address token, uint256 amount);
    event RageQuit(address delegate, address token, bool notified, string reason);

    /* data types */

    struct LockData {
        address delegate;
        address token;
        uint256 balance;
    }

    /* initialize function */

    function initialize() external;

    /* user functions */

    function lock(
        address token,
        uint256 amount,
        bytes calldata permission
    ) external;

    function unlock(
        address token,
        uint256 amount,
        bytes calldata permission
    ) external;

    function rageQuit(address delegate, address token)
        external
        returns (bool notified, string memory error);

    function transferERC20(
        address token,
        address to,
        uint256 amount
    ) external;

    function transferETH(address to, uint256 amount) external payable;

    /* pure functions */

    function calculateLockID(address delegate, address token)
        external
        pure
        returns (bytes32 lockID);

    /* getter functions */

    function getPermissionHash(
        bytes32 eip712TypeHash,
        address delegate,
        address token,
        uint256 amount,
        uint256 nonce
    ) external view returns (bytes32 permissionHash);

    function getNonce() external view returns (uint256 nonce);

    function owner() external view returns (address ownerAddress);

    function getLockSetCount() external view returns (uint256 count);

    function getLockAt(uint256 index) external view returns (LockData memory lockData);

    function getBalanceDelegated(address token, address delegate)
        external
        view
        returns (uint256 balance);

    function getBalanceLocked(address token) external view returns (uint256 balance);

    function checkBalances() external view returns (bool validity);
}

// File: contracts/interfaces/IVisorService.sol



// SPDX-License-Identifier: GPL-3.0-only
pragma solidity 0.7.6;

interface IVisorService {
    /* 
     * @dev Whenever an {IERC777} token is transferred to a subscriber vault via {IERC20-safeTransferFrom}
     * by `operator` from `from`, this function is called.
     *
     * It must return its Solidity selector to confirm the token transfer.
     * If any other value is returned or the interface is not implemented by the recipient, the transfer will be reverted.
     *
     * The selector can be obtained in Solidity with `IERC777.tokensReceived.selector`.
     */

  function subscriberTokensReceived(
        address token,
        address operator,
        address from,
        address to,
        uint256 amount,
        bytes calldata userData,
        bytes calldata operatorData
    ) external; 


}

// File: @openzeppelin/contracts/introspection/IERC165.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

/**
 * @dev Interface of the ERC165 standard, as defined in the
 * https://eips.ethereum.org/EIPS/eip-165[EIP].
 *
 * Implementers can declare support of contract interfaces, which can then be
 * queried by others ({ERC165Checker}).
 *
 * For an implementation, see {ERC165}.
 */
interface IERC165 {
    /**
     * @dev Returns true if this contract implements the interface defined by
     * `interfaceId`. See the corresponding
     * https://eips.ethereum.org/EIPS/eip-165#how-interfaces-are-identified[EIP section]
     * to learn more about how these ids are created.
     *
     * This function call must use less than 30 000 gas.
     */
    function supportsInterface(bytes4 interfaceId) external view returns (bool);
}

// File: @openzeppelin/contracts/cryptography/ECDSA.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

/**
 * @dev Elliptic Curve Digital Signature Algorithm (ECDSA) operations.
 *
 * These functions can be used to verify that a message was signed by the holder
 * of the private keys of a given address.
 */
library ECDSA {
    /**
     * @dev Returns the address that signed a hashed message (`hash`) with
     * `signature`. This address can then be used for verification purposes.
     *
     * The `ecrecover` EVM opcode allows for malleable (non-unique) signatures:
     * this function rejects them by requiring the `s` value to be in the lower
     * half order, and the `v` value to be either 27 or 28.
     *
     * IMPORTANT: `hash` _must_ be the result of a hash operation for the
     * verification to be secure: it is possible to craft signatures that
     * recover to arbitrary addresses for non-hashed data. A safe way to ensure
     * this is by receiving a hash of the original message (which may otherwise
     * be too long), and then calling {toEthSignedMessageHash} on it.
     */
    function recover(bytes32 hash, bytes memory signature) internal pure returns (address) {
        // Check the signature length
        if (signature.length != 65) {
            revert("ECDSA: invalid signature length");
        }

        // Divide the signature in r, s and v variables
        bytes32 r;
        bytes32 s;
        uint8 v;

        // ecrecover takes the signature parameters, and the only way to get them
        // currently is to use assembly.
        // solhint-disable-next-line no-inline-assembly
        assembly {
            r := mload(add(signature, 0x20))
            s := mload(add(signature, 0x40))
            v := byte(0, mload(add(signature, 0x60)))
        }

        return recover(hash, v, r, s);
    }

    /**
     * @dev Overload of {ECDSA-recover-bytes32-bytes-} that receives the `v`,
     * `r` and `s` signature fields separately.
     */
    function recover(bytes32 hash, uint8 v, bytes32 r, bytes32 s) internal pure returns (address) {
        // EIP-2 still allows signature malleability for ecrecover(). Remove this possibility and make the signature
        // unique. Appendix F in the Ethereum Yellow paper (https://ethereum.github.io/yellowpaper/paper.pdf), defines
        // the valid range for s in (281): 0 < s < secp256k1n ÷ 2 + 1, and for v in (282): v ∈ {27, 28}. Most
        // signatures from current libraries generate a unique signature with an s-value in the lower half order.
        //
        // If your library generates malleable signatures, such as s-values in the upper range, calculate a new s-value
        // with 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364141 - s1 and flip v from 27 to 28 or
        // vice versa. If your library also generates signatures with 0/1 for v instead 27/28, add 27 to v to accept
        // these malleable signatures as well.
        require(uint256(s) <= 0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF5D576E7357A4501DDFE92F46681B20A0, "ECDSA: invalid signature 's' value");
        require(v == 27 || v == 28, "ECDSA: invalid signature 'v' value");

        // If the signature is valid (and not malleable), return the signer address
        address signer = ecrecover(hash, v, r, s);
        require(signer != address(0), "ECDSA: invalid signature");

        return signer;
    }

    /**
     * @dev Returns an Ethereum Signed Message, created from a `hash`. This
     * replicates the behavior of the
     * https://github.com/ethereum/wiki/wiki/JSON-RPC#eth_sign[`eth_sign`]
     * JSON-RPC method.
     *
     * See {recover}.
     */
    function toEthSignedMessageHash(bytes32 hash) internal pure returns (bytes32) {
        // 32 is the length in bytes of hash,
        // enforced by the type signature above
        return keccak256(abi.encodePacked("\x19Ethereum Signed Message:\n32", hash));
    }
}

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



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

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

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

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

    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view virtual 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;
    }
}

// File: contracts/factory/IFactory.sol



// SPDX-License-Identifier: GPL-3.0-only
pragma solidity 0.7.6;

interface IFactory {
    function create(bytes calldata args) external returns (address instance);

    function create2(bytes calldata args, bytes32 salt) external returns (address instance);
}

// File: contracts/factory/InstanceRegistry.sol



// SPDX-License-Identifier: GPL-3.0-only
pragma solidity 0.7.6;

import {EnumerableSet} from "@openzeppelin/contracts/utils/EnumerableSet.sol";

interface IInstanceRegistry {
    /* events */

    event InstanceAdded(address instance);

    /* view functions */

    function isInstance(address instance) external view returns (bool validity);

    function instanceCount() external view returns (uint256 count);

    function instanceAt(uint256 index) external view returns (address instance);
}

/// @title InstanceRegistry
contract InstanceRegistry is IInstanceRegistry {
    using EnumerableSet for EnumerableSet.AddressSet;

    /* storage */

    EnumerableSet.AddressSet private _instanceSet;

    /* view functions */

    function isInstance(address instance) external view override returns (bool validity) {
        return _instanceSet.contains(instance);
    }

    function instanceCount() external view override returns (uint256 count) {
        return _instanceSet.length();
    }

    function instanceAt(uint256 index) external view override returns (address instance) {
        return _instanceSet.at(index);
    }

    /* admin functions */

    function _register(address instance) internal {
        require(_instanceSet.add(instance), "InstanceRegistry: already registered");
        emit InstanceAdded(instance);
    }
}

// File: contracts/hypervisor/RewardPool.sol



// SPDX-License-Identifier: GPL-3.0-only
pragma solidity 0.7.6;

import {IERC20} from "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import {Ownable} from "@openzeppelin/contracts/access/Ownable.sol";
import {TransferHelper} from "@uniswap/lib/contracts/libraries/TransferHelper.sol";

import {Powered} from "./Powered.sol";

interface IRewardPool {
    function sendERC20(
        address token,
        address to,
        uint256 value
    ) external;

    function rescueERC20(address[] calldata tokens, address recipient) external;
}

/// @title Reward Pool
/// @notice Vault for isolated storage of reward tokens
contract RewardPool is IRewardPool, Powered, Ownable {
    /* initializer */

    constructor(address powerSwitch) {
        Powered._setPowerSwitch(powerSwitch);
    }

    /* user functions */

    /// @notice Send an ERC20 token
    /// access control: only owner
    /// state machine:
    ///   - can be called multiple times
    ///   - only online
    /// state scope: none
    /// token transfer: transfer tokens from self to recipient
    /// @param token address The token to send
    /// @param to address The recipient to send to
    /// @param value uint256 Amount of tokens to send
    function sendERC20(
        address token,
        address to,
        uint256 value
    ) external override onlyOwner onlyOnline {
        TransferHelper.safeTransfer(token, to, value);
    }

    /* emergency functions */

    /// @notice Rescue multiple ERC20 tokens
    /// access control: only power controller
    /// state machine:
    ///   - can be called multiple times
    ///   - only shutdown
    /// state scope: none
    /// token transfer: transfer tokens from self to recipient
    /// @param tokens address[] The tokens to rescue
    /// @param recipient address The recipient to rescue to
    function rescueERC20(address[] calldata tokens, address recipient)
        external
        override
        onlyShutdown
    {
        // only callable by controller
        require(
            msg.sender == Powered.getPowerController(),
            "RewardPool: only controller can withdraw after shutdown"
        );

        // assert recipient is defined
        require(recipient != address(0), "RewardPool: recipient not defined");

        // transfer tokens
        for (uint256 index = 0; index < tokens.length; index++) {
            // get token
            address token = tokens[index];
            // get balance
            uint256 balance = IERC20(token).balanceOf(address(this));
            // transfer token
            TransferHelper.safeTransfer(token, recipient, balance);
        }
    }
}

// File: contracts/hypervisor/Powered.sol



// SPDX-License-Identifier: GPL-3.0-only
pragma solidity 0.7.6;

import {IPowerSwitch} from "./PowerSwitch.sol";

interface IPowered {
    function isOnline() external view returns (bool status);

    function isOffline() external view returns (bool status);

    function isShutdown() external view returns (bool status);

    function getPowerSwitch() external view returns (address powerSwitch);

    function getPowerController() external view returns (address controller);
}

/// @title Powered
/// @notice Helper for calling external PowerSwitch
contract Powered is IPowered {
    /* storage */

    address private _powerSwitch;

    /* modifiers */

    modifier onlyOnline() {
        _onlyOnline();
        _;
    }

    modifier onlyOffline() {
        _onlyOffline();
        _;
    }

    modifier notShutdown() {
        _notShutdown();
        _;
    }

    modifier onlyShutdown() {
        _onlyShutdown();
        _;
    }

    /* initializer */

    function _setPowerSwitch(address powerSwitch) internal {
        _powerSwitch = powerSwitch;
    }

    /* getter functions */

    function isOnline() public view override returns (bool status) {
        return IPowerSwitch(_powerSwitch).isOnline();
    }

    function isOffline() public view override returns (bool status) {
        return IPowerSwitch(_powerSwitch).isOffline();
    }

    function isShutdown() public view override returns (bool status) {
        return IPowerSwitch(_powerSwitch).isShutdown();
    }

    function getPowerSwitch() public view override returns (address powerSwitch) {
        return _powerSwitch;
    }

    function getPowerController() public view override returns (address controller) {
        return IPowerSwitch(_powerSwitch).getPowerController();
    }

    /* convenience functions */

    function _onlyOnline() private view {
        require(isOnline(), "Powered: is not online");
    }

    function _onlyOffline() private view {
        require(isOffline(), "Powered: is not offline");
    }

    function _notShutdown() private view {
        require(!isShutdown(), "Powered: is shutdown");
    }

    function _onlyShutdown() private view {
        require(isShutdown(), "Powered: is not shutdown");
    }
}

// File: contracts/hypervisor/PowerSwitch.sol



// SPDX-License-Identifier: GPL-3.0-only
pragma solidity 0.7.6;

import {Ownable} from "@openzeppelin/contracts/access/Ownable.sol";

interface IPowerSwitch {
    /* admin events */

    event PowerOn();
    event PowerOff();
    event EmergencyShutdown();

    /* data types */

    enum State {Online, Offline, Shutdown}

    /* admin functions */

    function powerOn() external;

    function powerOff() external;

    function emergencyShutdown() external;

    /* view functions */

    function isOnline() external view returns (bool status);

    function isOffline() external view returns (bool status);

    function isShutdown() external view returns (bool status);

    function getStatus() external view returns (State status);

    function getPowerController() external view returns (address controller);
}

/// @title PowerSwitch
/// @notice Standalone pausing and emergency stop functionality
contract PowerSwitch is IPowerSwitch, Ownable {
    /* storage */

    IPowerSwitch.State private _status;

    /* initializer */

    constructor(address owner) {
        // sanity check owner
        require(owner != address(0), "PowerSwitch: invalid owner");
        // transfer ownership
        Ownable.transferOwnership(owner);
    }

    /* admin functions */

    /// @notice Turn Power On
    /// access control: only admin
    /// state machine: only when offline
    /// state scope: only modify _status
    /// token transfer: none
    function powerOn() external override onlyOwner {
        require(_status == IPowerSwitch.State.Offline, "PowerSwitch: cannot power on");
        _status = IPowerSwitch.State.Online;
        emit PowerOn();
    }

    /// @notice Turn Power Off
    /// access control: only admin
    /// state machine: only when online
    /// state scope: only modify _status
    /// token transfer: none
    function powerOff() external override onlyOwner {
        require(_status == IPowerSwitch.State.Online, "PowerSwitch: cannot power off");
        _status = IPowerSwitch.State.Offline;
        emit PowerOff();
    }

    /// @notice Shutdown Permanently
    /// access control: only admin
    /// state machine:
    /// - when online or offline
    /// - can only be called once
    /// state scope: only modify _status
    /// token transfer: none
    function emergencyShutdown() external override onlyOwner {
        require(_status != IPowerSwitch.State.Shutdown, "PowerSwitch: cannot shutdown");
        _status = IPowerSwitch.State.Shutdown;
        emit EmergencyShutdown();
    }

    /* getter functions */

    function isOnline() external view override returns (bool status) {
        return _status == State.Online;
    }

    function isOffline() external view override returns (bool status) {
        return _status == State.Offline;
    }

    function isShutdown() external view override returns (bool status) {
        return _status == State.Shutdown;
    }

    function getStatus() external view override returns (IPowerSwitch.State status) {
        return _status;
    }

    function getPowerController() external view override returns (address controller) {
        return Ownable.owner();
    }
}