// File: contracts/distribution/WeightFeeder.sol



// SPDX-License-Identifier: MIT
pragma solidity >=0.7.0 <0.8.0;

import {SafeMath} from '@openzeppelin/contracts/math/SafeMath.sol';

import {IPoolStore, IPoolStoreGov} from './PoolStore.sol';
import {Operator} from '../access/Operator.sol';
import {IOracle} from '../oracle/Oracle.sol';
import {ICurve} from '../curve/Curve.sol';

contract WeightFeeder is Operator {
    using SafeMath for uint256;

    enum FeedStatus {Neutral, BelowPeg, AbovePeg}

    uint256 public constant ETH = 1e18;

    // gov
    address public token;
    address public target;
    address public curve;
    address public oracle;

    function setToken(address _newToken) public onlyOwner {
        token = _newToken;
    }

    function setTarget(address _newTarget) public onlyOwner {
        target = _newTarget;
    }

    function setCurve(address _newCurve) public onlyOwner {
        curve = _newCurve;
    }

    function setOracle(address _newOracle) public onlyOwner {
        oracle = _newOracle;
    }

    // pools
    uint256 public cashLP;
    uint256 public cashVault;
    uint256 public shareLP;
    uint256 public boardroom;
    uint256 public bondroom;
    uint256 public strategicPair;
    uint256 public communityFund;

    FeedStatus public lastUpdated = FeedStatus.Neutral;

    function configure(
        uint256 _cashLP,
        uint256 _cashVault,
        uint256 _shareLP,
        uint256 _boardroom,
        uint256 _bondroom,
        uint256 _strategicPair,
        uint256 _communityFund
    ) public onlyOwner {
        cashLP = _cashLP;
        cashVault = _cashVault;
        shareLP = _shareLP;
        boardroom = _boardroom;
        bondroom = _bondroom;
        strategicPair = _strategicPair;
        communityFund = _communityFund;
    }

    function feed() public onlyOperator {
        uint256 price = IOracle(oracle).consult(token, ETH);
        uint256 rate = ICurve(curve).calcCeiling(price);

        // 60 * 1e18
        IPoolStoreGov(target).setPool(cashLP, rate.mul(60));
        IPoolStoreGov(target).setPool(cashVault, ETH.sub(rate).mul(60));
        if (IPoolStore(target).weightOf(shareLP) != ETH.mul(10)) {
            IPoolStoreGov(target).setPool(shareLP, ETH.mul(10));
        }

        // below peg
        if (lastUpdated != FeedStatus.BelowPeg && price < ETH) {
            /*
                15% BAS boardroom stakers
                5% BAB staking pool
                5% Strategic pairs
                5% CDF/Vision fund
            */
            IPoolStoreGov(target).setPool(boardroom, ETH.mul(15));
            IPoolStoreGov(target).setPool(bondroom, ETH.mul(5));
            IPoolStoreGov(target).setPool(strategicPair, ETH.mul(5));
            IPoolStoreGov(target).setPool(communityFund, ETH.mul(5));

            lastUpdated = FeedStatus.BelowPeg;
        }

        // above peg
        if (lastUpdated != FeedStatus.AbovePeg && price >= ETH) {
            /*
                5% BAS boardroom stakers
                0% BAB staking pool
                10% Strategic pairs
                15% the CDF/Vision fund
            */
            IPoolStoreGov(target).setPool(boardroom, ETH.mul(5));
            IPoolStoreGov(target).setPool(bondroom, 0);
            IPoolStoreGov(target).setPool(strategicPair, ETH.mul(10));
            IPoolStoreGov(target).setPool(communityFund, ETH.mul(15));

            lastUpdated = FeedStatus.AbovePeg;
        }
    }
}

// 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: contracts/distribution/PoolStore.sol



// SPDX-License-Identifier: MIT
pragma solidity >=0.7.0 <0.8.0;

import {SafeMath} from '@openzeppelin/contracts/math/SafeMath.sol';
import {IERC20} from '@openzeppelin/contracts/token/ERC20/IERC20.sol';
import {SafeERC20} from '@openzeppelin/contracts/token/ERC20/SafeERC20.sol';

import {Operator} from '../access/Operator.sol';

interface IPoolStore {
    /* ================= EVENTS ================= */
    event Deposit(
        address indexed operator,
        address indexed owner,
        uint256 indexed pid,
        uint256 amount
    );
    event Withdraw(
        address indexed operator,
        address indexed owner,
        uint256 indexed pid,
        uint256 amount
    );

    /* ================= CALLS ================= */

    // common
    function totalWeight() external view returns (uint256);

    function poolLength() external view returns (uint256);

    // index
    function poolIdsOf(address _token) external view returns (uint256[] memory);

    // pool info
    function nameOf(uint256 _pid) external view returns (string memory);

    function tokenOf(uint256 _pid) external view returns (address);

    function weightOf(uint256 _pid) external view returns (uint256);

    function totalSupply(uint256 _pid) external view returns (uint256);

    function balanceOf(uint256 _pid, address _owner)
        external
        view
        returns (uint256);

    /* ================= TXNS ================= */

    function deposit(
        uint256 _pid,
        address _owner,
        uint256 _amount
    ) external;

    function withdraw(
        uint256 _pid,
        address _owner,
        uint256 _amount
    ) external;

    function emergencyWithdraw(uint256 _pid) external;
}

interface IPoolStoreGov {
    /* ================= EVENTS ================= */

    event EmergencyReported(address indexed reporter);
    event EmergencyResolved(address indexed resolver);

    event WeightFeederChanged(
        address indexed operator,
        address indexed oldFeeder,
        address indexed newFeeder
    );

    event PoolAdded(
        address indexed operator,
        uint256 indexed pid,
        string name,
        address token,
        uint256 weight
    );
    event PoolWeightChanged(
        address indexed operator,
        uint256 indexed pid,
        uint256 from,
        uint256 to
    );
    event PoolNameChanged(
        address indexed operator,
        uint256 indexed pid,
        string from,
        string to
    );

    /* ================= TXNS ================= */

    // emergency
    function reportEmergency() external;

    function resolveEmergency() external;

    // feeder
    function setWeightFeeder(address _newFeeder) external;

    // pool setting
    function addPool(
        string memory _name,
        IERC20 _token,
        uint256 _weight
    ) external;

    function setPool(uint256 _pid, uint256 _weight) external;

    function setPool(uint256 _pid, string memory _name) external;
}

contract PoolStore is IPoolStore, IPoolStoreGov, Operator {
    using SafeMath for uint256;
    using SafeERC20 for IERC20;

    /* ================= DATA STRUCTURE ================= */

    struct Pool {
        string name;
        IERC20 token;
        uint256 weight;
        uint256 totalSupply;
    }

    /* ================= STATES ================= */

    uint256 public override totalWeight = 0;

    Pool[] public pools;
    mapping(uint256 => mapping(address => uint256)) balances;
    mapping(address => uint256[]) public indexByToken;

    bool public emergency = false;
    address public weightFeeder;

    constructor() Operator() {
        weightFeeder = _msgSender();
    }

    /* ================= GOV - OWNER ONLY ================= */

    /**
     * @dev CAUTION: DO NOT USE IN NORMAL SITUATION
     * @notice Enable emergency withdraw
     */
    function reportEmergency() public override onlyOwner {
        emergency = true;
        emit EmergencyReported(_msgSender());
    }

    /**
     * @dev CAUTION: DO NOT USE IN NORMAL SITUATION
     * @notice Disable emergency withdraw
     */
    function resolveEmergency() public override onlyOwner {
        emergency = false;
        emit EmergencyResolved(_msgSender());
    }

    /*
     * @param _newFeeder weight feeder address to change
     */
    function setWeightFeeder(address _newFeeder) public override onlyOwner {
        address oldFeeder = weightFeeder;
        weightFeeder = _newFeeder;
        emit WeightFeederChanged(_msgSender(), oldFeeder, _newFeeder);
    }

    /**
     * @param _token pool token
     * @param _weight pool weight
     */
    function addPool(
        string memory _name,
        IERC20 _token,
        uint256 _weight
    ) public override onlyOwner {
        totalWeight = totalWeight.add(_weight);

        uint256 index = pools.length;
        indexByToken[address(_token)].push(index);

        pools.push(
            Pool({name: _name, token: _token, weight: _weight, totalSupply: 0})
        );
        emit PoolAdded(_msgSender(), index, _name, address(_token), _weight);
    }

    /**
     * @param _pid pool id
     * @param _weight target pool weight
     */
    function setPool(uint256 _pid, uint256 _weight)
        public
        override
        onlyWeightFeeder
        checkPoolId(_pid)
    {
        Pool memory pool = pools[_pid];

        uint256 oldWeight = pool.weight;
        totalWeight = totalWeight.add(_weight).sub(pool.weight);
        pool.weight = _weight;

        pools[_pid] = pool;

        emit PoolWeightChanged(_msgSender(), _pid, oldWeight, _weight);
    }

    /**
     * @param _pid pool id
     * @param _name name of pool
     */
    function setPool(uint256 _pid, string memory _name)
        public
        override
        checkPoolId(_pid)
        onlyOwner
    {
        string memory oldName = pools[_pid].name;
        pools[_pid].name = _name;

        emit PoolNameChanged(_msgSender(), _pid, oldName, _name);
    }

    /* ================= MODIFIER ================= */

    modifier onlyWeightFeeder {
        require(_msgSender() == weightFeeder, 'PoolStore: unauthorized');

        _;
    }

    modifier checkPoolId(uint256 _pid) {
        require(_pid <= pools.length, 'PoolStore: invalid pid');

        _;
    }

    /* ================= CALLS - ANYONE ================= */
    /**
     * @return total pool length
     */
    function poolLength() public view override returns (uint256) {
        return pools.length;
    }

    /**
     * @param _token pool token address
     * @return pool id
     */
    function poolIdsOf(address _token)
        public
        view
        override
        returns (uint256[] memory)
    {
        return indexByToken[_token];
    }

    /**
     * @param _pid pool id
     * @return name of pool
     */
    function nameOf(uint256 _pid)
        public
        view
        override
        checkPoolId(_pid)
        returns (string memory)
    {
        return pools[_pid].name;
    }

    /**
     * @param _pid pool id
     * @return pool token
     */
    function tokenOf(uint256 _pid)
        public
        view
        override
        checkPoolId(_pid)
        returns (address)
    {
        return address(pools[_pid].token);
    }

    /**
     * @param _pid pool id
     * @return pool weight
     */
    function weightOf(uint256 _pid)
        public
        view
        override
        checkPoolId(_pid)
        returns (uint256)
    {
        return pools[_pid].weight;
    }

    /**
     * @param _pid pool id
     * @return total staked token amount
     */
    function totalSupply(uint256 _pid)
        public
        view
        override
        checkPoolId(_pid)
        returns (uint256)
    {
        return pools[_pid].totalSupply;
    }

    /**
     * @param _pid pool id
     * @param _sender staker address
     * @return staked amount of user
     */
    function balanceOf(uint256 _pid, address _sender)
        public
        view
        override
        checkPoolId(_pid)
        returns (uint256)
    {
        return balances[_pid][_sender];
    }

    /* ================= TXNS - OPERATOR ONLY ================= */

    /**
     * @param _pid pool id
     * @param _owner stake address
     * @param _amount stake amount
     */
    function deposit(
        uint256 _pid,
        address _owner,
        uint256 _amount
    ) public override checkPoolId(_pid) onlyOperator {
        pools[_pid].totalSupply = pools[_pid].totalSupply.add(_amount);
        balances[_pid][_owner] = balances[_pid][_owner].add(_amount);
        IERC20(tokenOf(_pid)).safeTransferFrom(
            _msgSender(),
            address(this),
            _amount
        );

        emit Deposit(_msgSender(), _owner, _pid, _amount);
    }

    function _withdraw(
        uint256 _pid,
        address _owner,
        uint256 _amount
    ) internal {
        pools[_pid].totalSupply = pools[_pid].totalSupply.sub(_amount);
        balances[_pid][_owner] = balances[_pid][_owner].sub(_amount);
        IERC20(tokenOf(_pid)).safeTransfer(_msgSender(), _amount);

        emit Withdraw(_msgSender(), _owner, _pid, _amount);
    }

    /**
     * @param _pid pool id
     * @param _owner stake address
     * @param _amount stake amount
     */
    function withdraw(
        uint256 _pid,
        address _owner,
        uint256 _amount
    ) public override checkPoolId(_pid) onlyOperator {
        _withdraw(_pid, _owner, _amount);
    }

    /**
     * @notice Anyone can withdraw its balance even if is not the operator
     * @param _pid pool id
     */
    function emergencyWithdraw(uint256 _pid) public override checkPoolId(_pid) {
        require(emergency, 'PoolStore: not in emergency');
        _withdraw(_pid, msg.sender, balanceOf(_pid, _msgSender()));
    }
}

// File: contracts/access/Operator.sol



// SPDX-License-Identifier: MIT
pragma solidity >=0.7.0 <0.8.0;

import {Context, Ownable} from '@openzeppelin/contracts/access/Ownable.sol';

abstract contract Operator is Context, Ownable {
    address private _operator;

    event OperatorTransferred(
        address indexed previousOperator,
        address indexed newOperator
    );

    constructor() {
        _operator = _msgSender();
        emit OperatorTransferred(address(0), _operator);
    }

    function operator() public view returns (address) {
        return _operator;
    }

    modifier onlyOperator() {
        require(
            _operator == _msgSender(),
            'operator: caller is not the operator'
        );
        _;
    }

    function isOperator() public view returns (bool) {
        return _msgSender() == _operator;
    }

    function transferOperator(address newOperator_) public onlyOwner {
        _transferOperator(newOperator_);
    }

    function _transferOperator(address newOperator_) internal {
        require(
            newOperator_ != address(0),
            'operator: zero address given for new operator'
        );
        emit OperatorTransferred(address(0), newOperator_);
        _operator = newOperator_;
    }
}

// File: contracts/oracle/Oracle.sol



// SPDX-License-Identifier: MIT
pragma solidity >=0.7.0 <0.8.0;

import {SafeMath} from '@openzeppelin/contracts/math/SafeMath.sol';

import {Babylonian} from '../lib/Babylonian.sol';
import {FixedPoint} from '../lib/FixedPoint.sol';
import {UniswapV2Library} from '../lib/UniswapV2Library.sol';
import {UniswapV2OracleLibrary} from '../lib/UniswapV2OracleLibrary.sol';
import {Epoch} from '../utils/Epoch.sol';
import {IUniswapV2Pair} from '../interfaces/IUniswapV2Pair.sol';
import {IUniswapV2Factory} from '../interfaces/IUniswapV2Factory.sol';

interface IOracle {
    function update() external;

    function consult(address token, uint256 amountIn)
        external
        view
        returns (uint256 amountOut);
    // function getReserves() external view returns (uint112 reserve0, uint112 reserve1, uint32 blockTimestamp);
}

// fixed window oracle that recomputes the average price for the entire period once every period
// note that the price average is only guaranteed to be over at least 1 period, but may be over a longer period
contract Oracle is Epoch {
    using FixedPoint for *;
    using SafeMath for uint256;

    /* ========== STATE VARIABLES ========== */

    // uniswap
    address public token0;
    address public token1;
    IUniswapV2Pair public pair;

    // oracle
    uint32 public blockTimestampLast;
    uint256 public price0CumulativeLast;
    uint256 public price1CumulativeLast;
    FixedPoint.uq112x112 public price0Average;
    FixedPoint.uq112x112 public price1Average;

    /* ========== CONSTRUCTOR ========== */

    constructor(
        address _factory,
        address _tokenA,
        address _tokenB,
        uint256 _period,
        uint256 _startTime
    ) Epoch(_period, _startTime, 0) {
        IUniswapV2Pair _pair =
            IUniswapV2Pair(
                UniswapV2Library.pairFor(_factory, _tokenA, _tokenB)
            );
        pair = _pair;
        token0 = _pair.token0();
        token1 = _pair.token1();
        price0CumulativeLast = _pair.price0CumulativeLast(); // fetch the current accumulated price value (1 / 0)
        price1CumulativeLast = _pair.price1CumulativeLast(); // fetch the current accumulated price value (0 / 1)
        uint112 reserve0;
        uint112 reserve1;
        (reserve0, reserve1, blockTimestampLast) = _pair.getReserves();
        require(reserve0 != 0 && reserve1 != 0, 'Oracle: NO_RESERVES'); // ensure that there's liquidity in the pair
    }

    /* ========== MUTABLE FUNCTIONS ========== */

    /** @dev Updates 1-day EMA price from Uniswap.  */
    function update() external checkEpoch {
        (
            uint256 price0Cumulative,
            uint256 price1Cumulative,
            uint32 blockTimestamp
        ) = UniswapV2OracleLibrary.currentCumulativePrices(address(pair));
        uint32 timeElapsed = blockTimestamp - blockTimestampLast; // overflow is desired

        if (timeElapsed == 0) {
            // prevent divided by zero
            return;
        }

        // overflow is desired, casting never truncates
        // cumulative price is in (uq112x112 price * seconds) units so we simply wrap it after division by time elapsed
        price0Average = FixedPoint.uq112x112(
            uint224((price0Cumulative - price0CumulativeLast) / timeElapsed)
        );
        price1Average = FixedPoint.uq112x112(
            uint224((price1Cumulative - price1CumulativeLast) / timeElapsed)
        );

        price0CumulativeLast = price0Cumulative;
        price1CumulativeLast = price1Cumulative;
        blockTimestampLast = blockTimestamp;

        emit Updated(price0Cumulative, price1Cumulative);
    }

    // note this will always return 0 before update has been called successfully for the first time.
    function consult(address token, uint256 amountIn)
        external
        view
        returns (uint144 amountOut)
    {
        if (token == token0) {
            amountOut = price0Average.mul(amountIn).decode144();
        } else {
            require(token == token1, 'Oracle: INVALID_TOKEN');
            amountOut = price1Average.mul(amountIn).decode144();
        }
    }

    // collaboration of update / consult
    function expectedPrice(address token, uint256 amountIn)
        external
        view
        returns (uint224 amountOut)
    {
        (
            uint256 price0Cumulative,
            uint256 price1Cumulative,
            uint32 blockTimestamp
        ) = UniswapV2OracleLibrary.currentCumulativePrices(address(pair));
        uint32 timeElapsed = blockTimestamp - blockTimestampLast; // overflow is desired

        FixedPoint.uq112x112 memory avg0 =
            FixedPoint.uq112x112(
                uint224((price0Cumulative - price0CumulativeLast) / timeElapsed)
            );
        FixedPoint.uq112x112 memory avg1 =
            FixedPoint.uq112x112(
                uint224((price1Cumulative - price1CumulativeLast) / timeElapsed)
            );

        if (token == token0) {
            amountOut = avg0.mul(amountIn).decode144();
        } else {
            require(token == token1, 'Oracle: INVALID_TOKEN');
            amountOut = avg1.mul(amountIn).decode144();
        }
        return amountOut;
    }

    function pairFor(
        address factory,
        address tokenA,
        address tokenB
    ) external pure returns (address lpt) {
        return UniswapV2Library.pairFor(factory, tokenA, tokenB);
    }

    event Updated(uint256 price0CumulativeLast, uint256 price1CumulativeLast);
}

// File: contracts/curve/Curve.sol



// SPDX-License-Identifier: MIT
pragma solidity >=0.7.0 <0.8.0;

interface ICurve {
    function minSupply() external view returns (uint256);

    function maxSupply() external view returns (uint256);

    function minCeiling() external view returns (uint256);

    function maxCeiling() external view returns (uint256);

    function calcCeiling(uint256 _supply) external view returns (uint256);
}

abstract contract Curve is ICurve {
    /* ========== EVENTS ========== */

    event MinSupplyChanged(
        address indexed operator,
        uint256 _old,
        uint256 _new
    );

    event MaxSupplyChanged(
        address indexed operator,
        uint256 _old,
        uint256 _new
    );

    event MinCeilingChanged(
        address indexed operator,
        uint256 _old,
        uint256 _new
    );

    event MaxCeilingChanged(
        address indexed operator,
        uint256 _old,
        uint256 _new
    );

    /* ========== STATE VARIABLES ========== */

    uint256 public override minSupply;
    uint256 public override maxSupply;

    uint256 public override minCeiling;
    uint256 public override maxCeiling;

    /* ========== GOVERNANCE ========== */

    function setMinSupply(uint256 _newMinSupply) public virtual {
        uint256 oldMinSupply = minSupply;
        minSupply = _newMinSupply;
        emit MinSupplyChanged(msg.sender, oldMinSupply, _newMinSupply);
    }

    function setMaxSupply(uint256 _newMaxSupply) public virtual {
        uint256 oldMaxSupply = maxSupply;
        maxSupply = _newMaxSupply;
        emit MaxSupplyChanged(msg.sender, oldMaxSupply, _newMaxSupply);
    }

    function setMinCeiling(uint256 _newMinCeiling) public virtual {
        uint256 oldMinCeiling = _newMinCeiling;
        minCeiling = _newMinCeiling;
        emit MinCeilingChanged(msg.sender, oldMinCeiling, _newMinCeiling);
    }

    function setMaxCeiling(uint256 _newMaxCeiling) public virtual {
        uint256 oldMaxCeiling = _newMaxCeiling;
        maxCeiling = _newMaxCeiling;
        emit MaxCeilingChanged(msg.sender, oldMaxCeiling, _newMaxCeiling);
    }

    function calcCeiling(uint256 _supply)
        external
        view
        virtual
        override
        returns (uint256);
}

// 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: @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: @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: @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: contracts/lib/Babylonian.sol



// SPDX-License-Identifier: MIT
pragma solidity >=0.7.0 <0.8.0;

library Babylonian {
    function sqrt(uint256 y) internal pure returns (uint256 z) {
        if (y > 3) {
            z = y;
            uint256 x = y / 2 + 1;
            while (x < z) {
                z = x;
                x = (y / x + x) / 2;
            }
        } else if (y != 0) {
            z = 1;
        }
        // else z = 0
    }
}

// File: contracts/lib/FixedPoint.sol



// SPDX-License-Identifier: MIT
pragma solidity >=0.7.0 <0.8.0;

import {Babylonian} from './Babylonian.sol';

// a library for handling binary fixed point numbers (https://en.wikipedia.org/wiki/Q_(number_format))
library FixedPoint {
    // range: [0, 2**112 - 1]
    // resolution: 1 / 2**112
    struct uq112x112 {
        uint224 _x;
    }

    // range: [0, 2**144 - 1]
    // resolution: 1 / 2**112
    struct uq144x112 {
        uint256 _x;
    }

    uint8 private constant RESOLUTION = 112;
    uint256 private constant Q112 = uint256(1) << RESOLUTION;
    uint256 private constant Q224 = Q112 << RESOLUTION;

    // encode a uint112 as a UQ112x112
    function encode(uint112 x) internal pure returns (uq112x112 memory) {
        return uq112x112(uint224(x) << RESOLUTION);
    }

    // encodes a uint144 as a UQ144x112
    function encode144(uint144 x) internal pure returns (uq144x112 memory) {
        return uq144x112(uint256(x) << RESOLUTION);
    }

    // divide a UQ112x112 by a uint112, returning a UQ112x112
    function div(uq112x112 memory self, uint112 x)
        internal
        pure
        returns (uq112x112 memory)
    {
        require(x != 0, 'FixedPoint: DIV_BY_ZERO');
        return uq112x112(self._x / uint224(x));
    }

    // multiply a UQ112x112 by a uint, returning a UQ144x112
    // reverts on overflow
    function mul(uq112x112 memory self, uint256 y)
        internal
        pure
        returns (uq144x112 memory)
    {
        uint256 z;
        require(
            y == 0 || (z = uint256(self._x) * y) / y == uint256(self._x),
            'FixedPoint: MULTIPLICATION_OVERFLOW'
        );
        return uq144x112(z);
    }

    // returns a UQ112x112 which represents the ratio of the numerator to the denominator
    // equivalent to encode(numerator).div(denominator)
    function fraction(uint112 numerator, uint112 denominator)
        internal
        pure
        returns (uq112x112 memory)
    {
        require(denominator > 0, 'FixedPoint: DIV_BY_ZERO');
        return uq112x112((uint224(numerator) << RESOLUTION) / denominator);
    }

    // decode a UQ112x112 into a uint112 by truncating after the radix point
    function decode(uq112x112 memory self) internal pure returns (uint112) {
        return uint112(self._x >> RESOLUTION);
    }

    // decode a UQ144x112 into a uint144 by truncating after the radix point
    function decode144(uq144x112 memory self) internal pure returns (uint144) {
        return uint144(self._x >> RESOLUTION);
    }

    // take the reciprocal of a UQ112x112
    function reciprocal(uq112x112 memory self)
        internal
        pure
        returns (uq112x112 memory)
    {
        require(self._x != 0, 'FixedPoint: ZERO_RECIPROCAL');
        return uq112x112(uint224(Q224 / self._x));
    }

    // square root of a UQ112x112
    function sqrt(uq112x112 memory self)
        internal
        pure
        returns (uq112x112 memory)
    {
        return uq112x112(uint224(Babylonian.sqrt(uint256(self._x)) << 56));
    }
}

// File: contracts/lib/UniswapV2Library.sol



// SPDX-License-Identifier: MIT
pragma solidity >=0.6.0 <0.8.0;

import {SafeMath} from '@openzeppelin/contracts/math/SafeMath.sol';

import {IUniswapV2Pair} from '../interfaces/IUniswapV2Pair.sol';

library UniswapV2Library {
    using SafeMath for uint256;

    // returns sorted token addresses, used to handle return values from pairs sorted in this order
    function sortTokens(address tokenA, address tokenB)
        internal
        pure
        returns (address token0, address token1)
    {
        require(tokenA != tokenB, 'UniswapV2Library: IDENTICAL_ADDRESSES');
        (token0, token1) = tokenA < tokenB
            ? (tokenA, tokenB)
            : (tokenB, tokenA);
        require(token0 != address(0), 'UniswapV2Library: ZERO_ADDRESS');
    }

    // calculates the CREATE2 address for a pair without making any external calls
    function pairFor(
        address factory,
        address tokenA,
        address tokenB
    ) internal pure returns (address pair) {
        (address token0, address token1) = sortTokens(tokenA, tokenB);
        pair = address(
            uint256(
                keccak256(
                    abi.encodePacked(
                        hex'ff',
                        factory,
                        keccak256(abi.encodePacked(token0, token1)),
                        hex'96e8ac4277198ff8b6f785478aa9a39f403cb768dd02cbee326c3e7da348845f' // init code hash
                    )
                )
            )
        );
    }

    // fetches and sorts the reserves for a pair
    function getReserves(
        address factory,
        address tokenA,
        address tokenB
    ) internal view returns (uint256 reserveA, uint256 reserveB) {
        (address token0, ) = sortTokens(tokenA, tokenB);
        (uint256 reserve0, uint256 reserve1, ) =
            IUniswapV2Pair(pairFor(factory, tokenA, tokenB)).getReserves();
        (reserveA, reserveB) = tokenA == token0
            ? (reserve0, reserve1)
            : (reserve1, reserve0);
    }

    // given some amount of an asset and pair reserves, returns an equivalent amount of the other asset
    function quote(
        uint256 amountA,
        uint256 reserveA,
        uint256 reserveB
    ) internal pure returns (uint256 amountB) {
        require(amountA > 0, 'UniswapV2Library: INSUFFICIENT_AMOUNT');
        require(
            reserveA > 0 && reserveB > 0,
            'UniswapV2Library: INSUFFICIENT_LIQUIDITY'
        );
        amountB = amountA.mul(reserveB) / reserveA;
    }

    // given an input amount of an asset and pair reserves, returns the maximum output amount of the other asset
    function getAmountOut(
        uint256 amountIn,
        uint256 reserveIn,
        uint256 reserveOut
    ) internal pure returns (uint256 amountOut) {
        require(amountIn > 0, 'UniswapV2Library: INSUFFICIENT_INPUT_AMOUNT');
        require(
            reserveIn > 0 && reserveOut > 0,
            'UniswapV2Library: INSUFFICIENT_LIQUIDITY'
        );
        uint256 amountInWithFee = amountIn.mul(997);
        uint256 numerator = amountInWithFee.mul(reserveOut);
        uint256 denominator = reserveIn.mul(1000).add(amountInWithFee);
        amountOut = numerator / denominator;
    }

    // given an output amount of an asset and pair reserves, returns a required input amount of the other asset
    function getAmountIn(
        uint256 amountOut,
        uint256 reserveIn,
        uint256 reserveOut
    ) internal pure returns (uint256 amountIn) {
        require(amountOut > 0, 'UniswapV2Library: INSUFFICIENT_OUTPUT_AMOUNT');
        require(
            reserveIn > 0 && reserveOut > 0,
            'UniswapV2Library: INSUFFICIENT_LIQUIDITY'
        );
        uint256 numerator = reserveIn.mul(amountOut).mul(1000);
        uint256 denominator = reserveOut.sub(amountOut).mul(997);
        amountIn = (numerator / denominator).add(1);
    }

    // performs chained getAmountOut calculations on any number of pairs
    function getAmountsOut(
        address factory,
        uint256 amountIn,
        address[] memory path
    ) internal view returns (uint256[] memory amounts) {
        require(path.length >= 2, 'UniswapV2Library: INVALID_PATH');
        amounts = new uint256[](path.length);
        amounts[0] = amountIn;
        for (uint256 i; i < path.length - 1; i++) {
            (uint256 reserveIn, uint256 reserveOut) =
                getReserves(factory, path[i], path[i + 1]);
            amounts[i + 1] = getAmountOut(amounts[i], reserveIn, reserveOut);
        }
    }

    // performs chained getAmountIn calculations on any number of pairs
    function getAmountsIn(
        address factory,
        uint256 amountOut,
        address[] memory path
    ) internal view returns (uint256[] memory amounts) {
        require(path.length >= 2, 'UniswapV2Library: INVALID_PATH');
        amounts = new uint256[](path.length);
        amounts[amounts.length - 1] = amountOut;
        for (uint256 i = path.length - 1; i > 0; i--) {
            (uint256 reserveIn, uint256 reserveOut) =
                getReserves(factory, path[i - 1], path[i]);
            amounts[i - 1] = getAmountIn(amounts[i], reserveIn, reserveOut);
        }
    }
}

// File: contracts/lib/UniswapV2OracleLibrary.sol



// SPDX-License-Identifier: MIT
pragma solidity >=0.6.0 <0.8.0;

import {FixedPoint} from './FixedPoint.sol';
import {IUniswapV2Pair} from '../interfaces/IUniswapV2Pair.sol';

// library with helper methods for oracles that are concerned with computing average prices
library UniswapV2OracleLibrary {
    using FixedPoint for *;

    // helper function that returns the current block timestamp within the range of uint32, i.e. [0, 2**32 - 1]
    function currentBlockTimestamp() internal view returns (uint32) {
        return uint32(block.timestamp % 2**32);
    }

    // produces the cumulative price using counterfactuals to save gas and avoid a call to sync.
    function currentCumulativePrices(address pair)
        internal
        view
        returns (
            uint256 price0Cumulative,
            uint256 price1Cumulative,
            uint32 blockTimestamp
        )
    {
        blockTimestamp = currentBlockTimestamp();
        price0Cumulative = IUniswapV2Pair(pair).price0CumulativeLast();
        price1Cumulative = IUniswapV2Pair(pair).price1CumulativeLast();

        // if time has elapsed since the last update on the pair, mock the accumulated price values
        (uint112 reserve0, uint112 reserve1, uint32 blockTimestampLast) =
            IUniswapV2Pair(pair).getReserves();
        if (blockTimestampLast != blockTimestamp) {
            // subtraction overflow is desired
            uint32 timeElapsed = blockTimestamp - blockTimestampLast;
            // addition overflow is desired
            // counterfactual
            price0Cumulative +=
                uint256(FixedPoint.fraction(reserve1, reserve0)._x) *
                timeElapsed;
            // counterfactual
            price1Cumulative +=
                uint256(FixedPoint.fraction(reserve0, reserve1)._x) *
                timeElapsed;
        }
    }
}

// File: contracts/utils/Epoch.sol



// SPDX-License-Identifier: MIT
pragma solidity >=0.7.0 <0.8.0;

import '@openzeppelin/contracts/math/Math.sol';
import '@openzeppelin/contracts/math/SafeMath.sol';

import '../access/Operator.sol';

contract Epoch is Operator {
    using SafeMath for uint256;

    uint256 private period;
    uint256 private startTime;
    uint256 private lastExecutedAt;

    /* ========== CONSTRUCTOR ========== */

    constructor(
        uint256 _period,
        uint256 _startTime,
        uint256 _startEpoch
    ) {
        require(_startTime > block.timestamp, 'Epoch: invalid start time');
        period = _period;
        startTime = _startTime;
        lastExecutedAt = startTime.add(_startEpoch.mul(period));
    }

    /* ========== Modifier ========== */

    modifier checkStartTime {
        require(block.timestamp >= startTime, 'Epoch: not started yet');

        _;
    }

    modifier checkEpoch {
        require(block.timestamp > startTime, 'Epoch: not started yet');
        require(callable(), 'Epoch: not allowed');

        _;

        lastExecutedAt = block.timestamp;
    }

    /* ========== VIEW FUNCTIONS ========== */

    function callable() public view returns (bool) {
        return getCurrentEpoch() >= getNextEpoch();
    }

    // epoch
    function getLastEpoch() public view returns (uint256) {
        return lastExecutedAt.sub(startTime).div(period);
    }

    function getCurrentEpoch() public view returns (uint256) {
        return Math.max(startTime, block.timestamp).sub(startTime).div(period);
    }

    function getNextEpoch() public view returns (uint256) {
        if (startTime == lastExecutedAt) {
            return getLastEpoch();
        }
        return getLastEpoch().add(1);
    }

    function nextEpochPoint() public view returns (uint256) {
        return startTime.add(getNextEpoch().mul(period));
    }

    // params
    function getPeriod() public view returns (uint256) {
        return period;
    }

    function getStartTime() public view returns (uint256) {
        return startTime;
    }

    /* ========== GOVERNANCE ========== */

    function setPeriod(uint256 _period) external onlyOperator {
        period = _period;
    }
}

// File: contracts/interfaces/IUniswapV2Pair.sol



// SPDX-License-Identifier: MIT
pragma solidity >=0.7.0 <0.8.0;

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

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

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

    function decimals() external pure returns (uint8);

    function totalSupply() external view returns (uint256);

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

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

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

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

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

    function DOMAIN_SEPARATOR() external view returns (bytes32);

    function PERMIT_TYPEHASH() external pure returns (bytes32);

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

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

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

    function MINIMUM_LIQUIDITY() external pure returns (uint256);

    function factory() external view returns (address);

    function token0() external view returns (address);

    function token1() external view returns (address);

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

    function price0CumulativeLast() external view returns (uint256);

    function price1CumulativeLast() external view returns (uint256);

    function kLast() external view returns (uint256);

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

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

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

    function skim(address to) external;

    function sync() external;

    function initialize(address, address) external;
}

// File: contracts/interfaces/IUniswapV2Factory.sol



// SPDX-License-Identifier: MIT
pragma solidity >=0.7.0 <0.8.0;

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

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

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

    function allPairsLength() external view returns (uint256);

    function feeTo() external view returns (address);

    function feeToSetter() external view returns (address);

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

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



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

/**
 * @dev Standard math utilities missing in the Solidity language.
 */
library Math {
    /**
     * @dev Returns the largest of two numbers.
     */
    function max(uint256 a, uint256 b) internal pure returns (uint256) {
        return a >= b ? a : b;
    }

    /**
     * @dev Returns the smallest of two numbers.
     */
    function min(uint256 a, uint256 b) internal pure returns (uint256) {
        return a < b ? a : b;
    }

    /**
     * @dev Returns the average of two numbers. The result is rounded towards
     * zero.
     */
    function average(uint256 a, uint256 b) internal pure returns (uint256) {
        // (a + b) / 2 can overflow, so we distribute
        return (a / 2) + (b / 2) + ((a % 2 + b % 2) / 2);
    }
}