// File: contracts/pcv/balancer/BalancerLBPSwapper.sol



// SPDX-License-Identifier: GPL-3.0-or-later
pragma solidity ^0.8.0;

import "./manager/WeightedBalancerPoolManager.sol";
import "./IVault.sol";
import "../../utils/Timed.sol";
import "../../refs/OracleRef.sol";
import "../IPCVSwapper.sol";
import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";

/// @title BalancerLBPSwapper
/// @author Fei Protocol
/// @notice an auction contract which cyclically sells one token for another using Balancer LBP
contract BalancerLBPSwapper is IPCVSwapper, OracleRef, Timed, WeightedBalancerPoolManager {
    using Decimal for Decimal.D256;
    using SafeERC20 for IERC20;

    // ------------- Events -------------

    event WithdrawERC20(address indexed _caller, address indexed _token, address indexed _to, uint256 _amount);

    event ExitPool();

    event MinTokenSpentUpdate(uint256 oldMinTokenSpentBalance, uint256 newMinTokenSpentBalance);

    // ------------- Balancer State -------------
    /// @notice the Balancer LBP used for swapping
    IWeightedPool public pool;

    /// @notice the Balancer V2 Vault contract
    IVault public vault;

    /// @notice the Balancer V2 Pool id of `pool`
    bytes32 public pid;

    // Balancer constants for the weight changes
    uint256 public immutable SMALL_PERCENT;
    uint256 public immutable LARGE_PERCENT;

    // Balancer constants to memoize the target assets and weights from pool
    IAsset[] private assets;
    uint256[] private initialWeights;
    uint256[] private endWeights;

    // ------------- Swapper State -------------

    /// @notice the token to be auctioned
    address public immutable override tokenSpent;

    /// @notice the token to buy
    address public immutable override tokenReceived;

    /// @notice the address to send `tokenReceived`
    address public override tokenReceivingAddress;

    /// @notice the minimum amount of tokenSpent to kick off a new auction on swap()
    uint256 public minTokenSpentBalance;

    struct OracleData {
        address _oracle;
        address _backupOracle;
        // invert should be false if the oracle is reported in tokenSpent terms otherwise true
        bool _invertOraclePrice;
        // The decimalsNormalizer should be calculated as tokenSpent.decimals() - tokenReceived.decimals() if invert is false, otherwise reverse order
        int256 _decimalsNormalizer;
    }

    /**
    @notice constructor for BalancerLBPSwapper
    @param _core Core contract to reference
    @param oracleData The parameters needed to initialize the OracleRef
    @param _frequency minimum time between auctions and duration of auction
    @param _weightSmall the small weight of weight changes (e.g. 5%)
    @param _weightLarge the large weight of weight changes (e.g. 95%)
    @param _tokenSpent the token to be auctioned
    @param _tokenReceived the token to buy
    @param _tokenReceivingAddress the address to send `tokenReceived`
    @param _minTokenSpentBalance the minimum amount of tokenSpent to kick off a new auction on swap()
     */
    constructor(
        address _core,
        OracleData memory oracleData,
        uint256 _frequency,
        uint256 _weightSmall,
        uint256 _weightLarge,
        address _tokenSpent,
        address _tokenReceived,
        address _tokenReceivingAddress,
        uint256 _minTokenSpentBalance
    )
        OracleRef(
            _core,
            oracleData._oracle,
            oracleData._backupOracle,
            oracleData._decimalsNormalizer,
            oracleData._invertOraclePrice
        )
        Timed(_frequency)
        WeightedBalancerPoolManager()
    {
        // weight changes
        SMALL_PERCENT = _weightSmall;
        LARGE_PERCENT = _weightLarge;
        require(_weightSmall < _weightLarge, "BalancerLBPSwapper: bad weights");
        require(_weightSmall + _weightLarge == 1e18, "BalancerLBPSwapper: weights not normalized");

        // tokenSpent and tokenReceived are immutable
        tokenSpent = _tokenSpent;
        tokenReceived = _tokenReceived;

        _setReceivingAddress(_tokenReceivingAddress);
        _setMinTokenSpent(_minTokenSpentBalance);

        _setContractAdminRole(keccak256("SWAP_ADMIN_ROLE"));
    }

    /**
    @notice initialize Balancer LBP
    Needs to be a separate method because this contract needs to be deployed and supplied
    as the owner of the pool on construction.
    Includes various checks to ensure the pool contract is correct and initialization can only be done once
    @param _pool the Balancer LBP used for swapping
    */
    function init(IWeightedPool _pool) external {
        require(address(pool) == address(0), "BalancerLBPSwapper: initialized");
        _initTimed();

        pool = _pool;
        IVault _vault = _pool.getVault();

        vault = _vault;

        // Check ownership
        require(_pool.getOwner() == address(this), "BalancerLBPSwapper: contract not pool owner");

        // Check correct pool token components
        bytes32 _pid = _pool.getPoolId();
        pid = _pid;
        (IERC20[] memory tokens, , ) = _vault.getPoolTokens(_pid);
        require(tokens.length == 2, "BalancerLBPSwapper: pool does not have 2 tokens");
        require(
            tokenSpent == address(tokens[0]) || tokenSpent == address(tokens[1]),
            "BalancerLBPSwapper: tokenSpent not in pool"
        );
        require(
            tokenReceived == address(tokens[0]) || tokenReceived == address(tokens[1]),
            "BalancerLBPSwapper: tokenReceived not in pool"
        );

        // Set the asset array and target weights
        assets = new IAsset[](2);
        assets[0] = IAsset(address(tokens[0]));
        assets[1] = IAsset(address(tokens[1]));

        bool tokenSpentAtIndex0 = tokenSpent == address(tokens[0]);
        initialWeights = new uint256[](2);
        endWeights = new uint256[](2);

        if (tokenSpentAtIndex0) {
            initialWeights[0] = LARGE_PERCENT;
            initialWeights[1] = SMALL_PERCENT;

            endWeights[0] = SMALL_PERCENT;
            endWeights[1] = LARGE_PERCENT;
        } else {
            initialWeights[0] = SMALL_PERCENT;
            initialWeights[1] = LARGE_PERCENT;

            endWeights[0] = LARGE_PERCENT;
            endWeights[1] = SMALL_PERCENT;
        }

        // Approve pool tokens for vault
        _pool.approve(address(_vault), type(uint256).max);
        IERC20(tokenSpent).approve(address(_vault), type(uint256).max);
        IERC20(tokenReceived).approve(address(_vault), type(uint256).max);
    }

    /**
        @notice Swap algorithm
        1. Withdraw existing LP tokens
        2. Reset weights
        3. Provide new liquidity
        4. Trigger gradual weight change
        5. Transfer remaining tokenReceived to tokenReceivingAddress
        @dev assumes tokenSpent balance of contract exceeds minTokenSpentBalance to kick off a new auction
    */
    function swap() external override afterTime whenNotPaused onlyGovernorOrAdmin {
        _swap();
    }

    /**
        @notice Force a swap() call, without waiting afterTime.
        This should only be callable after init() call, when no
        other swap is happening (call reverts if weight change
        is in progress).
    */
    function forceSwap() external whenNotPaused onlyGovernor {
        _swap();
    }

    /// @notice redeeem all assets from LP pool
    /// @param to destination for withdrawn tokens
    function exitPool(address to) external onlyPCVController {
        _exitPool();
        _transferAll(tokenSpent, to);
        _transferAll(tokenReceived, to);
    }

    /// @notice withdraw ERC20 from the contract
    /// @param token address of the ERC20 to send
    /// @param to address destination of the ERC20
    /// @param amount quantity of ERC20 to send
    function withdrawERC20(
        address token,
        address to,
        uint256 amount
    ) public onlyPCVController {
        IERC20(token).safeTransfer(to, amount);
        emit WithdrawERC20(msg.sender, token, to, amount);
    }

    /// @notice returns when the next auction ends
    function swapEndTime() public view returns (uint256 endTime) {
        (, endTime, ) = pool.getGradualWeightUpdateParams();
    }

    /// @notice sets the minimum time between swaps
    /// @param _frequency minimum time between swaps in seconds
    function setSwapFrequency(uint256 _frequency) external onlyGovernorOrAdmin {
        _setDuration(_frequency);
    }

    /// @notice sets the minimum token spent balance
    /// @param newMinTokenSpentBalance minimum amount of FEI to trigger a new auction
    function setMinTokenSpent(uint256 newMinTokenSpentBalance) external onlyGovernorOrAdmin {
        _setMinTokenSpent(newMinTokenSpentBalance);
    }

    /// @notice Sets the address receiving swap's inbound tokens
    /// @param newTokenReceivingAddress the address that will receive tokens
    function setReceivingAddress(address newTokenReceivingAddress) external override onlyGovernorOrAdmin {
        _setReceivingAddress(newTokenReceivingAddress);
    }

    /// @notice return the amount of tokens needed to seed the next auction
    function getTokensIn(uint256 spentTokenBalance)
        external
        view
        returns (address[] memory tokens, uint256[] memory amountsIn)
    {
        tokens = new address[](2);
        tokens[0] = address(assets[0]);
        tokens[1] = address(assets[1]);

        return (tokens, _getTokensIn(spentTokenBalance));
    }

    /**
        @notice Swap algorithm
        1. Withdraw existing LP tokens
        2. Reset weights
        3. Provide new liquidity
        4. Trigger gradual weight change
        5. Transfer remaining tokenReceived to tokenReceivingAddress
        @dev assumes tokenSpent balance of contract exceeds minTokenSpentBalance to kick off a new auction
    */
    function _swap() internal {
        (, , uint256 lastChangeBlock) = vault.getPoolTokens(pid);

        // Ensures no actor can change the pool contents earlier in the block
        require(lastChangeBlock < block.number, "BalancerLBPSwapper: pool changed this block");

        uint256 bptTotal = pool.totalSupply();

        // Balancer locks a small amount of bptTotal after init, so 0 bpt means pool needs initializing
        if (bptTotal == 0) {
            _initializePool();
            return;
        }
        require(swapEndTime() < block.timestamp, "BalancerLBPSwapper: weight update in progress");

        // 1. Withdraw existing LP tokens (if currently held)
        _exitPool();

        // 2. Reset weights to LARGE_PERCENT:SMALL_PERCENT
        // Using current block time triggers immediate weight reset
        _updateWeightsGradually(pool, block.timestamp, block.timestamp, initialWeights);

        // 3. Provide new liquidity
        uint256 spentTokenBalance = IERC20(tokenSpent).balanceOf(address(this));
        require(spentTokenBalance > minTokenSpentBalance, "BalancerLBPSwapper: not enough for new swap");

        // uses exact tokens in encoding for deposit, supplying both tokens
        // will use some of the previously withdrawn tokenReceived to seed the 1% required for new auction
        uint256[] memory amountsIn = _getTokensIn(spentTokenBalance);
        bytes memory userData = abi.encode(IWeightedPool.JoinKind.EXACT_TOKENS_IN_FOR_BPT_OUT, amountsIn, 0);

        IVault.JoinPoolRequest memory joinRequest;
        joinRequest.assets = assets;
        joinRequest.maxAmountsIn = amountsIn;
        joinRequest.userData = userData;
        joinRequest.fromInternalBalance = false; // uses external balances because tokens are held by contract

        vault.joinPool(pid, address(this), payable(address(this)), joinRequest);

        // 4. Kick off new auction ending after `duration` seconds
        _updateWeightsGradually(pool, block.timestamp, block.timestamp + duration, endWeights);
        _initTimed(); // reset timer
        // 5. Send remaining tokenReceived to target
        _transferAll(tokenReceived, tokenReceivingAddress);
    }

    function _exitPool() internal {
        uint256 bptBalance = pool.balanceOf(address(this));
        if (bptBalance != 0) {
            IVault.ExitPoolRequest memory exitRequest;

            // Uses encoding for exact BPT IN withdrawal using all held BPT
            bytes memory userData = abi.encode(IWeightedPool.ExitKind.EXACT_BPT_IN_FOR_TOKENS_OUT, bptBalance);

            exitRequest.assets = assets;
            exitRequest.minAmountsOut = new uint256[](2); // 0 min
            exitRequest.userData = userData;
            exitRequest.toInternalBalance = false; // use external balances to be able to transfer out tokenReceived

            vault.exitPool(pid, address(this), payable(address(this)), exitRequest);
            emit ExitPool();
        }
    }

    function _transferAll(address token, address to) internal {
        IERC20 _token = IERC20(token);
        _token.safeTransfer(to, _token.balanceOf(address(this)));
    }

    function _setReceivingAddress(address newTokenReceivingAddress) internal {
        require(newTokenReceivingAddress != address(0), "BalancerLBPSwapper: zero address");
        address oldTokenReceivingAddress = tokenReceivingAddress;
        tokenReceivingAddress = newTokenReceivingAddress;
        emit UpdateReceivingAddress(oldTokenReceivingAddress, newTokenReceivingAddress);
    }

    function _initializePool() internal {
        // Balancer LBP initialization uses a unique JoinKind which only takes in amountsIn
        uint256 spentTokenBalance = IERC20(tokenSpent).balanceOf(address(this));
        require(spentTokenBalance >= minTokenSpentBalance, "BalancerLBPSwapper: not enough tokenSpent to init");

        uint256[] memory amountsIn = _getTokensIn(spentTokenBalance);
        bytes memory userData = abi.encode(IWeightedPool.JoinKind.INIT, amountsIn);

        IVault.JoinPoolRequest memory joinRequest;
        joinRequest.assets = assets;
        joinRequest.maxAmountsIn = amountsIn;
        joinRequest.userData = userData;
        joinRequest.fromInternalBalance = false;

        vault.joinPool(pid, address(this), payable(address(this)), joinRequest);

        // Kick off the first auction
        _updateWeightsGradually(pool, block.timestamp, block.timestamp + duration, endWeights);
        _initTimed();

        _transferAll(tokenReceived, tokenReceivingAddress);
    }

    function _getTokensIn(uint256 spentTokenBalance) internal view returns (uint256[] memory amountsIn) {
        amountsIn = new uint256[](2);

        uint256 receivedTokenBalance = readOracle()
            .mul(spentTokenBalance)
            .mul(SMALL_PERCENT)
            .div(LARGE_PERCENT)
            .asUint256();

        if (address(assets[0]) == tokenSpent) {
            amountsIn[0] = spentTokenBalance;
            amountsIn[1] = receivedTokenBalance;
        } else {
            amountsIn[0] = receivedTokenBalance;
            amountsIn[1] = spentTokenBalance;
        }
    }

    function _setMinTokenSpent(uint256 newMinTokenSpentBalance) internal {
        uint256 oldMinTokenSpentBalance = minTokenSpentBalance;
        minTokenSpentBalance = newMinTokenSpentBalance;
        emit MinTokenSpentUpdate(oldMinTokenSpentBalance, newMinTokenSpentBalance);
    }
}

// File: contracts/pcv/balancer/manager/WeightedBalancerPoolManager.sol



// SPDX-License-Identifier: GPL-3.0-or-later
pragma solidity ^0.8.0;

import "./IWeightedBalancerPoolManager.sol";
import "./BaseBalancerPoolManager.sol";

/// @title WeightedBalancerPoolManager
/// @notice an abstract utility class for a contract that manages a Balancer WeightedPool (including LBP)
/// exposes the governable methods to Fei Governors or admins
abstract contract WeightedBalancerPoolManager is IWeightedBalancerPoolManager, BaseBalancerPoolManager {
    constructor() BaseBalancerPoolManager() {}

    function setSwapEnabled(IWeightedPool pool, bool swapEnabled) public override onlyGovernorOrAdmin {
        pool.setSwapEnabled(swapEnabled);
    }

    function updateWeightsGradually(
        IWeightedPool pool,
        uint256 startTime,
        uint256 endTime,
        uint256[] memory endWeights
    ) public override onlyGovernorOrAdmin {
        _updateWeightsGradually(pool, startTime, endTime, endWeights);
    }

    function _updateWeightsGradually(
        IWeightedPool pool,
        uint256 startTime,
        uint256 endTime,
        uint256[] memory endWeights
    ) internal {
        pool.updateWeightsGradually(startTime, endTime, endWeights);
    }

    function withdrawCollectedManagementFees(IWeightedPool pool, address recipient)
        public
        override
        onlyGovernorOrAdmin
    {
        pool.withdrawCollectedManagementFees(recipient);
    }
}

// File: contracts/pcv/balancer/IVault.sol



// SPDX-License-Identifier: GPL-3.0-or-later
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

pragma experimental ABIEncoderV2;

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

pragma solidity ^0.8.0;

interface IAsset {}

// interface with required methods from Balancer V2 IVault
// https://github.com/balancer-labs/balancer-v2-monorepo/blob/389b52f1fc9e468de854810ce9dc3251d2d5b212/pkg/vault/contracts/interfaces/IVault.sol

/**
 * @dev Full external interface for the Vault core contract - no external or public methods exist in the contract that
 * don't override one of these declarations.
 */
interface IVault {
    // Generalities about the Vault:
    //
    // - Whenever documentation refers to 'tokens', it strictly refers to ERC20-compliant token contracts. Tokens are
    // transferred out of the Vault by calling the `IERC20.transfer` function, and transferred in by calling
    // `IERC20.transferFrom`. In these cases, the sender must have previously allowed the Vault to use their tokens by
    // calling `IERC20.approve`. The only deviation from the ERC20 standard that is supported is functions not returning
    // a boolean value: in these scenarios, a non-reverting call is assumed to be successful.
    //
    // - All non-view functions in the Vault are non-reentrant: calling them while another one is mid-execution (e.g.
    // while execution control is transferred to a token contract during a swap) will result in a revert. View
    // functions can be called in a re-reentrant way, but doing so might cause them to return inconsistent results.
    // Contracts calling view functions in the Vault must make sure the Vault has not already been entered.
    //
    // - View functions revert if referring to either unregistered Pools, or unregistered tokens for registered Pools.

    // Authorizer
    //
    // Some system actions are permissioned, like setting and collecting protocol fees. This permissioning system exists
    // outside of the Vault in the Authorizer contract: the Vault simply calls the Authorizer to check if the caller
    // can perform a given action.

    // Relayers
    //
    // Additionally, it is possible for an account to perform certain actions on behalf of another one, using their
    // Vault ERC20 allowance and Internal Balance. These accounts are said to be 'relayers' for these Vault functions,
    // and are expected to be smart contracts with sound authentication mechanisms. For an account to be able to wield
    // this power, two things must occur:
    //  - The Authorizer must grant the account the permission to be a relayer for the relevant Vault function. This
    //    means that Balancer governance must approve each individual contract to act as a relayer for the intended
    //    functions.
    //  - Each user must approve the relayer to act on their behalf.
    // This double protection means users cannot be tricked into approving malicious relayers (because they will not
    // have been allowed by the Authorizer via governance), nor can malicious relayers approved by a compromised
    // Authorizer or governance drain user funds, since they would also need to be approved by each individual user.

    /**
     * @dev Returns true if `user` has approved `relayer` to act as a relayer for them.
     */
    function hasApprovedRelayer(address user, address relayer) external view returns (bool);

    /**
     * @dev Allows `relayer` to act as a relayer for `sender` if `approved` is true, and disallows it otherwise.
     *
     * Emits a `RelayerApprovalChanged` event.
     */
    function setRelayerApproval(
        address sender,
        address relayer,
        bool approved
    ) external;

    /**
     * @dev Emitted every time a relayer is approved or disapproved by `setRelayerApproval`.
     */
    event RelayerApprovalChanged(address indexed relayer, address indexed sender, bool approved);

    // Internal Balance
    //
    // Users can deposit tokens into the Vault, where they are allocated to their Internal Balance, and later
    // transferred or withdrawn. It can also be used as a source of tokens when joining Pools, as a destination
    // when exiting them, and as either when performing swaps. This usage of Internal Balance results in greatly reduced
    // gas costs when compared to relying on plain ERC20 transfers, leading to large savings for frequent users.
    //
    // Internal Balance management features batching, which means a single contract call can be used to perform multiple
    // operations of different kinds, with different senders and recipients, at once.

    /**
     * @dev Returns `user`'s Internal Balance for a set of tokens.
     */
    function getInternalBalance(address user, IERC20[] memory tokens) external view returns (uint256[] memory);

    /**
     * @dev Performs a set of user balance operations, which involve Internal Balance (deposit, withdraw or transfer)
     * and plain ERC20 transfers using the Vault's allowance. This last feature is particularly useful for relayers, as
     * it lets integrators reuse a user's Vault allowance.
     *
     * For each operation, if the caller is not `sender`, it must be an authorized relayer for them.
     */
    function manageUserBalance(UserBalanceOp[] memory ops) external payable;

    /**
     * @dev Data for `manageUserBalance` operations, which include the possibility for ETH to be sent and received
     without manual WETH wrapping or unwrapping.
     */
    struct UserBalanceOp {
        UserBalanceOpKind kind;
        IAsset asset;
        uint256 amount;
        address sender;
        address payable recipient;
    }

    // There are four possible operations in `manageUserBalance`:
    //
    // - DEPOSIT_INTERNAL
    // Increases the Internal Balance of the `recipient` account by transferring tokens from the corresponding
    // `sender`. The sender must have allowed the Vault to use their tokens via `IERC20.approve()`.
    //
    // ETH can be used by passing the ETH sentinel value as the asset and forwarding ETH in the call: it will be wrapped
    // and deposited as WETH. Any ETH amount remaining will be sent back to the caller (not the sender, which is
    // relevant for relayers).
    //
    // Emits an `InternalBalanceChanged` event.
    //
    //
    // - WITHDRAW_INTERNAL
    // Decreases the Internal Balance of the `sender` account by transferring tokens to the `recipient`.
    //
    // ETH can be used by passing the ETH sentinel value as the asset. This will deduct WETH instead, unwrap it and send
    // it to the recipient as ETH.
    //
    // Emits an `InternalBalanceChanged` event.
    //
    //
    // - TRANSFER_INTERNAL
    // Transfers tokens from the Internal Balance of the `sender` account to the Internal Balance of `recipient`.
    //
    // Reverts if the ETH sentinel value is passed.
    //
    // Emits an `InternalBalanceChanged` event.
    //
    //
    // - TRANSFER_EXTERNAL
    // Transfers tokens from `sender` to `recipient`, using the Vault's ERC20 allowance. This is typically used by
    // relayers, as it lets them reuse a user's Vault allowance.
    //
    // Reverts if the ETH sentinel value is passed.
    //
    // Emits an `ExternalBalanceTransfer` event.

    enum UserBalanceOpKind {
        DEPOSIT_INTERNAL,
        WITHDRAW_INTERNAL,
        TRANSFER_INTERNAL,
        TRANSFER_EXTERNAL
    }

    /**
     * @dev Emitted when a user's Internal Balance changes, either from calls to `manageUserBalance`, or through
     * interacting with Pools using Internal Balance.
     *
     * Because Internal Balance works exclusively with ERC20 tokens, ETH deposits and withdrawals will use the WETH
     * address.
     */
    event InternalBalanceChanged(address indexed user, IERC20 indexed token, int256 delta);

    /**
     * @dev Emitted when a user's Vault ERC20 allowance is used by the Vault to transfer tokens to an external account.
     */
    event ExternalBalanceTransfer(IERC20 indexed token, address indexed sender, address recipient, uint256 amount);

    // Pools
    //
    // There are three specialization settings for Pools, which allow for cheaper swaps at the cost of reduced
    // functionality:
    //
    //  - General: no specialization, suited for all Pools. IGeneralPool is used for swap request callbacks, passing the
    // balance of all tokens in the Pool. These Pools have the largest swap costs (because of the extra storage reads),
    // which increase with the number of registered tokens.
    //
    //  - Minimal Swap Info: IMinimalSwapInfoPool is used instead of IGeneralPool, which saves gas by only passing the
    // balance of the two tokens involved in the swap. This is suitable for some pricing algorithms, like the weighted
    // constant product one popularized by Balancer V1. Swap costs are smaller compared to general Pools, and are
    // independent of the number of registered tokens.
    //
    //  - Two Token: only allows two tokens to be registered. This achieves the lowest possible swap gas cost. Like
    // minimal swap info Pools, these are called via IMinimalSwapInfoPool.

    enum PoolSpecialization {
        GENERAL,
        MINIMAL_SWAP_INFO,
        TWO_TOKEN
    }

    /**
     * @dev Registers the caller account as a Pool with a given specialization setting. Returns the Pool's ID, which
     * is used in all Pool-related functions. Pools cannot be deregistered, nor can the Pool's specialization be
     * changed.
     *
     * The caller is expected to be a smart contract that implements either `IGeneralPool` or `IMinimalSwapInfoPool`,
     * depending on the chosen specialization setting. This contract is known as the Pool's contract.
     *
     * Note that the same contract may register itself as multiple Pools with unique Pool IDs, or in other words,
     * multiple Pools may share the same contract.
     *
     * Emits a `PoolRegistered` event.
     */
    function registerPool(PoolSpecialization specialization) external returns (bytes32);

    /**
     * @dev Emitted when a Pool is registered by calling `registerPool`.
     */
    event PoolRegistered(bytes32 indexed poolId, address indexed poolAddress, PoolSpecialization specialization);

    /**
     * @dev Returns a Pool's contract address and specialization setting.
     */
    function getPool(bytes32 poolId) external view returns (address, PoolSpecialization);

    /**
     * @dev Registers `tokens` for the `poolId` Pool. Must be called by the Pool's contract.
     *
     * Pools can only interact with tokens they have registered. Users join a Pool by transferring registered tokens,
     * exit by receiving registered tokens, and can only swap registered tokens.
     *
     * Each token can only be registered once. For Pools with the Two Token specialization, `tokens` must have a length
     * of two, that is, both tokens must be registered in the same `registerTokens` call, and they must be sorted in
     * ascending order.
     *
     * The `tokens` and `assetManagers` arrays must have the same length, and each entry in these indicates the Asset
     * Manager for the corresponding token. Asset Managers can manage a Pool's tokens via `managePoolBalance`,
     * depositing and withdrawing them directly, and can even set their balance to arbitrary amounts. They are therefore
     * expected to be highly secured smart contracts with sound design principles, and the decision to register an
     * Asset Manager should not be made lightly.
     *
     * Pools can choose not to assign an Asset Manager to a given token by passing in the zero address. Once an Asset
     * Manager is set, it cannot be changed except by deregistering the associated token and registering again with a
     * different Asset Manager.
     *
     * Emits a `TokensRegistered` event.
     */
    function registerTokens(
        bytes32 poolId,
        IERC20[] memory tokens,
        address[] memory assetManagers
    ) external;

    /**
     * @dev Emitted when a Pool registers tokens by calling `registerTokens`.
     */
    event TokensRegistered(bytes32 indexed poolId, IERC20[] tokens, address[] assetManagers);

    /**
     * @dev Deregisters `tokens` for the `poolId` Pool. Must be called by the Pool's contract.
     *
     * Only registered tokens (via `registerTokens`) can be deregistered. Additionally, they must have zero total
     * balance. For Pools with the Two Token specialization, `tokens` must have a length of two, that is, both tokens
     * must be deregistered in the same `deregisterTokens` call.
     *
     * A deregistered token can be re-registered later on, possibly with a different Asset Manager.
     *
     * Emits a `TokensDeregistered` event.
     */
    function deregisterTokens(bytes32 poolId, IERC20[] memory tokens) external;

    /**
     * @dev Emitted when a Pool deregisters tokens by calling `deregisterTokens`.
     */
    event TokensDeregistered(bytes32 indexed poolId, IERC20[] tokens);

    /**
     * @dev Returns detailed information for a Pool's registered token.
     *
     * `cash` is the number of tokens the Vault currently holds for the Pool. `managed` is the number of tokens
     * withdrawn and held outside the Vault by the Pool's token Asset Manager. The Pool's total balance for `token`
     * equals the sum of `cash` and `managed`.
     *
     * Internally, `cash` and `managed` are stored using 112 bits. No action can ever cause a Pool's token `cash`,
     * `managed` or `total` balance to be greater than 2^112 - 1.
     *
     * `lastChangeBlock` is the number of the block in which `token`'s total balance was last modified (via either a
     * join, exit, swap, or Asset Manager update). This value is useful to avoid so-called 'sandwich attacks', for
     * example when developing price oracles. A change of zero (e.g. caused by a swap with amount zero) is considered a
     * change for this purpose, and will update `lastChangeBlock`.
     *
     * `assetManager` is the Pool's token Asset Manager.
     */
    function getPoolTokenInfo(bytes32 poolId, IERC20 token)
        external
        view
        returns (
            uint256 cash,
            uint256 managed,
            uint256 lastChangeBlock,
            address assetManager
        );

    /**
     * @dev Returns a Pool's registered tokens, the total balance for each, and the latest block when *any* of
     * the tokens' `balances` changed.
     *
     * The order of the `tokens` array is the same order that will be used in `joinPool`, `exitPool`, as well as in all
     * Pool hooks (where applicable). Calls to `registerTokens` and `deregisterTokens` may change this order.
     *
     * If a Pool only registers tokens once, and these are sorted in ascending order, they will be stored in the same
     * order as passed to `registerTokens`.
     *
     * Total balances include both tokens held by the Vault and those withdrawn by the Pool's Asset Managers. These are
     * the amounts used by joins, exits and swaps. For a detailed breakdown of token balances, use `getPoolTokenInfo`
     * instead.
     */
    function getPoolTokens(bytes32 poolId)
        external
        view
        returns (
            IERC20[] memory tokens,
            uint256[] memory balances,
            uint256 lastChangeBlock
        );

    /**
     * @dev Called by users to join a Pool, which transfers tokens from `sender` into the Pool's balance. This will
     * trigger custom Pool behavior, which will typically grant something in return to `recipient` - often tokenized
     * Pool shares.
     *
     * If the caller is not `sender`, it must be an authorized relayer for them.
     *
     * The `assets` and `maxAmountsIn` arrays must have the same length, and each entry indicates the maximum amount
     * to send for each asset. The amounts to send are decided by the Pool and not the Vault: it just enforces
     * these maximums.
     *
     * If joining a Pool that holds WETH, it is possible to send ETH directly: the Vault will do the wrapping. To enable
     * this mechanism, the IAsset sentinel value (the zero address) must be passed in the `assets` array instead of the
     * WETH address. Note that it is not possible to combine ETH and WETH in the same join. Any excess ETH will be sent
     * back to the caller (not the sender, which is important for relayers).
     *
     * `assets` must have the same length and order as the array returned by `getPoolTokens`. This prevents issues when
     * interacting with Pools that register and deregister tokens frequently. If sending ETH however, the array must be
     * sorted *before* replacing the WETH address with the ETH sentinel value (the zero address), which means the final
     * `assets` array might not be sorted. Pools with no registered tokens cannot be joined.
     *
     * If `fromInternalBalance` is true, the caller's Internal Balance will be preferred: ERC20 transfers will only
     * be made for the difference between the requested amount and Internal Balance (if any). Note that ETH cannot be
     * withdrawn from Internal Balance: attempting to do so will trigger a revert.
     *
     * This causes the Vault to call the `IBasePool.onJoinPool` hook on the Pool's contract, where Pools implement
     * their own custom logic. This typically requires additional information from the user (such as the expected number
     * of Pool shares). This can be encoded in the `userData` argument, which is ignored by the Vault and passed
     * directly to the Pool's contract, as is `recipient`.
     *
     * Emits a `PoolBalanceChanged` event.
     */
    function joinPool(
        bytes32 poolId,
        address sender,
        address recipient,
        JoinPoolRequest memory request
    ) external payable;

    struct JoinPoolRequest {
        IAsset[] assets;
        uint256[] maxAmountsIn;
        bytes userData;
        bool fromInternalBalance;
    }

    /**
     * @dev Called by users to exit a Pool, which transfers tokens from the Pool's balance to `recipient`. This will
     * trigger custom Pool behavior, which will typically ask for something in return from `sender` - often tokenized
     * Pool shares. The amount of tokens that can be withdrawn is limited by the Pool's `cash` balance (see
     * `getPoolTokenInfo`).
     *
     * If the caller is not `sender`, it must be an authorized relayer for them.
     *
     * The `tokens` and `minAmountsOut` arrays must have the same length, and each entry in these indicates the minimum
     * token amount to receive for each token contract. The amounts to send are decided by the Pool and not the Vault:
     * it just enforces these minimums.
     *
     * If exiting a Pool that holds WETH, it is possible to receive ETH directly: the Vault will do the unwrapping. To
     * enable this mechanism, the IAsset sentinel value (the zero address) must be passed in the `assets` array instead
     * of the WETH address. Note that it is not possible to combine ETH and WETH in the same exit.
     *
     * `assets` must have the same length and order as the array returned by `getPoolTokens`. This prevents issues when
     * interacting with Pools that register and deregister tokens frequently. If receiving ETH however, the array must
     * be sorted *before* replacing the WETH address with the ETH sentinel value (the zero address), which means the
     * final `assets` array might not be sorted. Pools with no registered tokens cannot be exited.
     *
     * If `toInternalBalance` is true, the tokens will be deposited to `recipient`'s Internal Balance. Otherwise,
     * an ERC20 transfer will be performed. Note that ETH cannot be deposited to Internal Balance: attempting to
     * do so will trigger a revert.
     *
     * `minAmountsOut` is the minimum amount of tokens the user expects to get out of the Pool, for each token in the
     * `tokens` array. This array must match the Pool's registered tokens.
     *
     * This causes the Vault to call the `IBasePool.onExitPool` hook on the Pool's contract, where Pools implement
     * their own custom logic. This typically requires additional information from the user (such as the expected number
     * of Pool shares to return). This can be encoded in the `userData` argument, which is ignored by the Vault and
     * passed directly to the Pool's contract.
     *
     * Emits a `PoolBalanceChanged` event.
     */
    function exitPool(
        bytes32 poolId,
        address sender,
        address payable recipient,
        ExitPoolRequest memory request
    ) external;

    struct ExitPoolRequest {
        IAsset[] assets;
        uint256[] minAmountsOut;
        bytes userData;
        bool toInternalBalance;
    }

    /**
     * @dev Emitted when a user joins or exits a Pool by calling `joinPool` or `exitPool`, respectively.
     */
    event PoolBalanceChanged(
        bytes32 indexed poolId,
        address indexed liquidityProvider,
        IERC20[] tokens,
        int256[] deltas,
        uint256[] protocolFeeAmounts
    );

    enum PoolBalanceChangeKind {
        JOIN,
        EXIT
    }

    // Swaps
    //
    // Users can swap tokens with Pools by calling the `swap` and `batchSwap` functions. To do this,
    // they need not trust Pool contracts in any way: all security checks are made by the Vault. They must however be
    // aware of the Pools' pricing algorithms in order to estimate the prices Pools will quote.
    //
    // The `swap` function executes a single swap, while `batchSwap` can perform multiple swaps in sequence.
    // In each individual swap, tokens of one kind are sent from the sender to the Pool (this is the 'token in'),
    // and tokens of another kind are sent from the Pool to the recipient in exchange (this is the 'token out').
    // More complex swaps, such as one token in to multiple tokens out can be achieved by batching together
    // individual swaps.
    //
    // There are two swap kinds:
    //  - 'given in' swaps, where the amount of tokens in (sent to the Pool) is known, and the Pool determines (via the
    // `onSwap` hook) the amount of tokens out (to send to the recipient).
    //  - 'given out' swaps, where the amount of tokens out (received from the Pool) is known, and the Pool determines
    // (via the `onSwap` hook) the amount of tokens in (to receive from the sender).
    //
    // Additionally, it is possible to chain swaps using a placeholder input amount, which the Vault replaces with
    // the calculated output of the previous swap. If the previous swap was 'given in', this will be the calculated
    // tokenOut amount. If the previous swap was 'given out', it will use the calculated tokenIn amount. These extended
    // swaps are known as 'multihop' swaps, since they 'hop' through a number of intermediate tokens before arriving at
    // the final intended token.
    //
    // In all cases, tokens are only transferred in and out of the Vault (or withdrawn from and deposited into Internal
    // Balance) after all individual swaps have been completed, and the net token balance change computed. This makes
    // certain swap patterns, such as multihops, or swaps that interact with the same token pair in multiple Pools, cost
    // much less gas than they would otherwise.
    //
    // It also means that under certain conditions it is possible to perform arbitrage by swapping with multiple
    // Pools in a way that results in net token movement out of the Vault (profit), with no tokens being sent in (only
    // updating the Pool's internal accounting).
    //
    // To protect users from front-running or the market changing rapidly, they supply a list of 'limits' for each token
    // involved in the swap, where either the maximum number of tokens to send (by passing a positive value) or the
    // minimum amount of tokens to receive (by passing a negative value) is specified.
    //
    // Additionally, a 'deadline' timestamp can also be provided, forcing the swap to fail if it occurs after
    // this point in time (e.g. if the transaction failed to be included in a block promptly).
    //
    // If interacting with Pools that hold WETH, it is possible to both send and receive ETH directly: the Vault will do
    // the wrapping and unwrapping. To enable this mechanism, the IAsset sentinel value (the zero address) must be
    // passed in the `assets` array instead of the WETH address. Note that it is possible to combine ETH and WETH in the
    // same swap. Any excess ETH will be sent back to the caller (not the sender, which is relevant for relayers).
    //
    // Finally, Internal Balance can be used when either sending or receiving tokens.

    enum SwapKind {
        GIVEN_IN,
        GIVEN_OUT
    }

    /**
     * @dev Performs a swap with a single Pool.
     *
     * If the swap is 'given in' (the number of tokens to send to the Pool is known), it returns the amount of tokens
     * taken from the Pool, which must be greater than or equal to `limit`.
     *
     * If the swap is 'given out' (the number of tokens to take from the Pool is known), it returns the amount of tokens
     * sent to the Pool, which must be less than or equal to `limit`.
     *
     * Internal Balance usage and the recipient are determined by the `funds` struct.
     *
     * Emits a `Swap` event.
     */
    function swap(
        SingleSwap memory singleSwap,
        FundManagement memory funds,
        uint256 limit,
        uint256 deadline
    ) external payable returns (uint256);

    /**
     * @dev Data for a single swap executed by `swap`. `amount` is either `amountIn` or `amountOut` depending on
     * the `kind` value.
     *
     * `assetIn` and `assetOut` are either token addresses, or the IAsset sentinel value for ETH (the zero address).
     * Note that Pools never interact with ETH directly: it will be wrapped to or unwrapped from WETH by the Vault.
     *
     * The `userData` field is ignored by the Vault, but forwarded to the Pool in the `onSwap` hook, and may be
     * used to extend swap behavior.
     */
    struct SingleSwap {
        bytes32 poolId;
        SwapKind kind;
        IAsset assetIn;
        IAsset assetOut;
        uint256 amount;
        bytes userData;
    }

    /**
     * @dev Performs a series of swaps with one or multiple Pools. In each individual swap, the caller determines either
     * the amount of tokens sent to or received from the Pool, depending on the `kind` value.
     *
     * Returns an array with the net Vault asset balance deltas. Positive amounts represent tokens (or ETH) sent to the
     * Vault, and negative amounts represent tokens (or ETH) sent by the Vault. Each delta corresponds to the asset at
     * the same index in the `assets` array.
     *
     * Swaps are executed sequentially, in the order specified by the `swaps` array. Each array element describes a
     * Pool, the token to be sent to this Pool, the token to receive from it, and an amount that is either `amountIn` or
     * `amountOut` depending on the swap kind.
     *
     * Multihop swaps can be executed by passing an `amount` value of zero for a swap. This will cause the amount in/out
     * of the previous swap to be used as the amount in for the current one. In a 'given in' swap, 'tokenIn' must equal
     * the previous swap's `tokenOut`. For a 'given out' swap, `tokenOut` must equal the previous swap's `tokenIn`.
     *
     * The `assets` array contains the addresses of all assets involved in the swaps. These are either token addresses,
     * or the IAsset sentinel value for ETH (the zero address). Each entry in the `swaps` array specifies tokens in and
     * out by referencing an index in `assets`. Note that Pools never interact with ETH directly: it will be wrapped to
     * or unwrapped from WETH by the Vault.
     *
     * Internal Balance usage, sender, and recipient are determined by the `funds` struct. The `limits` array specifies
     * the minimum or maximum amount of each token the vault is allowed to transfer.
     *
     * `batchSwap` can be used to make a single swap, like `swap` does, but doing so requires more gas than the
     * equivalent `swap` call.
     *
     * Emits `Swap` events.
     */
    function batchSwap(
        SwapKind kind,
        BatchSwapStep[] memory swaps,
        IAsset[] memory assets,
        FundManagement memory funds,
        int256[] memory limits,
        uint256 deadline
    ) external payable returns (int256[] memory);

    /**
     * @dev Data for each individual swap executed by `batchSwap`. The asset in and out fields are indexes into the
     * `assets` array passed to that function, and ETH assets are converted to WETH.
     *
     * If `amount` is zero, the multihop mechanism is used to determine the actual amount based on the amount in/out
     * from the previous swap, depending on the swap kind.
     *
     * The `userData` field is ignored by the Vault, but forwarded to the Pool in the `onSwap` hook, and may be
     * used to extend swap behavior.
     */
    struct BatchSwapStep {
        bytes32 poolId;
        uint256 assetInIndex;
        uint256 assetOutIndex;
        uint256 amount;
        bytes userData;
    }

    /**
     * @dev Emitted for each individual swap performed by `swap` or `batchSwap`.
     */
    event Swap(
        bytes32 indexed poolId,
        IERC20 indexed tokenIn,
        IERC20 indexed tokenOut,
        uint256 amountIn,
        uint256 amountOut
    );

    /**
     * @dev All tokens in a swap are either sent from the `sender` account to the Vault, or from the Vault to the
     * `recipient` account.
     *
     * If the caller is not `sender`, it must be an authorized relayer for them.
     *
     * If `fromInternalBalance` is true, the `sender`'s Internal Balance will be preferred, performing an ERC20
     * transfer for the difference between the requested amount and the User's Internal Balance (if any). The `sender`
     * must have allowed the Vault to use their tokens via `IERC20.approve()`. This matches the behavior of
     * `joinPool`.
     *
     * If `toInternalBalance` is true, tokens will be deposited to `recipient`'s internal balance instead of
     * transferred. This matches the behavior of `exitPool`.
     *
     * Note that ETH cannot be deposited to or withdrawn from Internal Balance: attempting to do so will trigger a
     * revert.
     */
    struct FundManagement {
        address sender;
        bool fromInternalBalance;
        address payable recipient;
        bool toInternalBalance;
    }

    /**
     * @dev Simulates a call to `batchSwap`, returning an array of Vault asset deltas. Calls to `swap` cannot be
     * simulated directly, but an equivalent `batchSwap` call can and will yield the exact same result.
     *
     * Each element in the array corresponds to the asset at the same index, and indicates the number of tokens (or ETH)
     * the Vault would take from the sender (if positive) or send to the recipient (if negative). The arguments it
     * receives are the same that an equivalent `batchSwap` call would receive.
     *
     * Unlike `batchSwap`, this function performs no checks on the sender or recipient field in the `funds` struct.
     * This makes it suitable to be called by off-chain applications via eth_call without needing to hold tokens,
     * approve them for the Vault, or even know a user's address.
     *
     * Note that this function is not 'view' (due to implementation details): the client code must explicitly execute
     * eth_call instead of eth_sendTransaction.
     */
    function queryBatchSwap(
        SwapKind kind,
        BatchSwapStep[] memory swaps,
        IAsset[] memory assets,
        FundManagement memory funds
    ) external returns (int256[] memory assetDeltas);

    // Asset Management
    //
    // Each token registered for a Pool can be assigned an Asset Manager, which is able to freely withdraw the Pool's
    // tokens from the Vault, deposit them, or assign arbitrary values to its `managed` balance (see
    // `getPoolTokenInfo`). This makes them extremely powerful and dangerous. Even if an Asset Manager only directly
    // controls one of the tokens in a Pool, a malicious manager could set that token's balance to manipulate the
    // prices of the other tokens, and then drain the Pool with swaps. The risk of using Asset Managers is therefore
    // not constrained to the tokens they are managing, but extends to the entire Pool's holdings.
    //
    // However, a properly designed Asset Manager smart contract can be safely used for the Pool's benefit,
    // for example by lending unused tokens out for interest, or using them to participate in voting protocols.
    //
    // This concept is unrelated to the IAsset interface.

    /**
     * @dev Performs a set of Pool balance operations, which may be either withdrawals, deposits or updates.
     *
     * Pool Balance management features batching, which means a single contract call can be used to perform multiple
     * operations of different kinds, with different Pools and tokens, at once.
     *
     * For each operation, the caller must be registered as the Asset Manager for `token` in `poolId`.
     */
    function managePoolBalance(PoolBalanceOp[] memory ops) external;

    struct PoolBalanceOp {
        PoolBalanceOpKind kind;
        bytes32 poolId;
        IERC20 token;
        uint256 amount;
    }

    /**
     * Withdrawals decrease the Pool's cash, but increase its managed balance, leaving the total balance unchanged.
     *
     * Deposits increase the Pool's cash, but decrease its managed balance, leaving the total balance unchanged.
     *
     * Updates don't affect the Pool's cash balance, but because the managed balance changes, it does alter the total.
     * The external amount can be either increased or decreased by this call (i.e., reporting a gain or a loss).
     */
    enum PoolBalanceOpKind {
        WITHDRAW,
        DEPOSIT,
        UPDATE
    }

    /**
     * @dev Emitted when a Pool's token Asset Manager alters its balance via `managePoolBalance`.
     */
    event PoolBalanceManaged(
        bytes32 indexed poolId,
        address indexed assetManager,
        IERC20 indexed token,
        int256 cashDelta,
        int256 managedDelta
    );

    /**
     * @dev Safety mechanism to pause most Vault operations in the event of an emergency - typically detection of an
     * error in some part of the system.
     *
     * The Vault can only be paused during an initial time period, after which pausing is forever disabled.
     *
     * While the contract is paused, the following features are disabled:
     * - depositing and transferring internal balance
     * - transferring external balance (using the Vault's allowance)
     * - swaps
     * - joining Pools
     * - Asset Manager interactions
     *
     * Internal Balance can still be withdrawn, and Pools exited.
     */
    function setPaused(bool paused) external;
}

// File: contracts/utils/Timed.sol



// SPDX-License-Identifier: GPL-3.0-or-later
pragma solidity ^0.8.4;

/// @title an abstract contract for timed events
/// @author Fei Protocol
abstract contract Timed {
    /// @notice the start timestamp of the timed period
    uint256 public startTime;

    /// @notice the duration of the timed period
    uint256 public duration;

    event DurationUpdate(uint256 oldDuration, uint256 newDuration);

    event TimerReset(uint256 startTime);

    constructor(uint256 _duration) {
        _setDuration(_duration);
    }

    modifier duringTime() {
        require(isTimeStarted(), "Timed: time not started");
        require(!isTimeEnded(), "Timed: time ended");
        _;
    }

    modifier afterTime() {
        require(isTimeEnded(), "Timed: time not ended");
        _;
    }

    /// @notice return true if time period has ended
    function isTimeEnded() public view returns (bool) {
        return remainingTime() == 0;
    }

    /// @notice number of seconds remaining until time is up
    /// @return remaining
    function remainingTime() public view returns (uint256) {
        return duration - timeSinceStart(); // duration always >= timeSinceStart which is on [0,d]
    }

    /// @notice number of seconds since contract was initialized
    /// @return timestamp
    /// @dev will be less than or equal to duration
    function timeSinceStart() public view returns (uint256) {
        if (!isTimeStarted()) {
            return 0; // uninitialized
        }
        uint256 _duration = duration;
        uint256 timePassed = block.timestamp - startTime; // block timestamp always >= startTime
        return timePassed > _duration ? _duration : timePassed;
    }

    function isTimeStarted() public view returns (bool) {
        return startTime != 0;
    }

    function _initTimed() internal {
        startTime = block.timestamp;

        emit TimerReset(block.timestamp);
    }

    function _setDuration(uint256 newDuration) internal {
        require(newDuration != 0, "Timed: zero duration");

        uint256 oldDuration = duration;
        duration = newDuration;
        emit DurationUpdate(oldDuration, newDuration);
    }
}

// File: contracts/refs/OracleRef.sol



// SPDX-License-Identifier: GPL-3.0-or-later
pragma solidity ^0.8.4;

import "./IOracleRef.sol";
import "./CoreRef.sol";
import "@openzeppelin/contracts/utils/math/SafeCast.sol";
import "@openzeppelin/contracts/token/ERC20/extensions/IERC20Metadata.sol";

/// @title Reference to an Oracle
/// @author Fei Protocol
/// @notice defines some utilities around interacting with the referenced oracle
abstract contract OracleRef is IOracleRef, CoreRef {
    using Decimal for Decimal.D256;
    using SafeCast for int256;

    /// @notice the oracle reference by the contract
    IOracle public override oracle;

    /// @notice the backup oracle reference by the contract
    IOracle public override backupOracle;

    /// @notice number of decimals to scale oracle price by, i.e. multiplying by 10^(decimalsNormalizer)
    int256 public override decimalsNormalizer;

    bool public override doInvert;

    /// @notice OracleRef constructor
    /// @param _core Fei Core to reference
    /// @param _oracle oracle to reference
    /// @param _backupOracle backup oracle to reference
    /// @param _decimalsNormalizer number of decimals to normalize the oracle feed if necessary
    /// @param _doInvert invert the oracle price if this flag is on
    constructor(
        address _core,
        address _oracle,
        address _backupOracle,
        int256 _decimalsNormalizer,
        bool _doInvert
    ) CoreRef(_core) {
        _setOracle(_oracle);
        if (_backupOracle != address(0) && _backupOracle != _oracle) {
            _setBackupOracle(_backupOracle);
        }
        _setDoInvert(_doInvert);
        _setDecimalsNormalizer(_decimalsNormalizer);
    }

    /// @notice sets the referenced oracle
    /// @param newOracle the new oracle to reference
    function setOracle(address newOracle) external override onlyGovernor {
        _setOracle(newOracle);
    }

    /// @notice sets the flag for whether to invert or not
    /// @param newDoInvert the new flag for whether to invert
    function setDoInvert(bool newDoInvert) external override onlyGovernor {
        _setDoInvert(newDoInvert);
    }

    /// @notice sets the new decimalsNormalizer
    /// @param newDecimalsNormalizer the new decimalsNormalizer
    function setDecimalsNormalizer(int256 newDecimalsNormalizer) external override onlyGovernor {
        _setDecimalsNormalizer(newDecimalsNormalizer);
    }

    /// @notice sets the referenced backup oracle
    /// @param newBackupOracle the new backup oracle to reference
    function setBackupOracle(address newBackupOracle) external override onlyGovernorOrAdmin {
        _setBackupOracle(newBackupOracle);
    }

    /// @notice invert a peg price
    /// @param price the peg price to invert
    /// @return the inverted peg as a Decimal
    /// @dev the inverted peg would be X per FEI
    function invert(Decimal.D256 memory price) public pure override returns (Decimal.D256 memory) {
        return Decimal.one().div(price);
    }

    /// @notice updates the referenced oracle
    function updateOracle() public override {
        oracle.update();
    }

    /// @notice the peg price of the referenced oracle
    /// @return the peg as a Decimal
    /// @dev the peg is defined as FEI per X with X being ETH, dollars, etc
    function readOracle() public view override returns (Decimal.D256 memory) {
        (Decimal.D256 memory _peg, bool valid) = oracle.read();
        if (!valid && address(backupOracle) != address(0)) {
            (_peg, valid) = backupOracle.read();
        }
        require(valid, "OracleRef: oracle invalid");

        // Scale the oracle price by token decimals delta if necessary
        uint256 scalingFactor;
        if (decimalsNormalizer < 0) {
            scalingFactor = 10**(-1 * decimalsNormalizer).toUint256();
            _peg = _peg.div(scalingFactor);
        } else {
            scalingFactor = 10**decimalsNormalizer.toUint256();
            _peg = _peg.mul(scalingFactor);
        }

        // Invert the oracle price if necessary
        if (doInvert) {
            _peg = invert(_peg);
        }
        return _peg;
    }

    function _setOracle(address newOracle) internal {
        require(newOracle != address(0), "OracleRef: zero address");
        address oldOracle = address(oracle);
        oracle = IOracle(newOracle);
        emit OracleUpdate(oldOracle, newOracle);
    }

    // Supports zero address if no backup
    function _setBackupOracle(address newBackupOracle) internal {
        address oldBackupOracle = address(backupOracle);
        backupOracle = IOracle(newBackupOracle);
        emit BackupOracleUpdate(oldBackupOracle, newBackupOracle);
    }

    function _setDoInvert(bool newDoInvert) internal {
        bool oldDoInvert = doInvert;
        doInvert = newDoInvert;

        if (oldDoInvert != newDoInvert) {
            _setDecimalsNormalizer(-1 * decimalsNormalizer);
        }

        emit InvertUpdate(oldDoInvert, newDoInvert);
    }

    function _setDecimalsNormalizer(int256 newDecimalsNormalizer) internal {
        int256 oldDecimalsNormalizer = decimalsNormalizer;
        decimalsNormalizer = newDecimalsNormalizer;
        emit DecimalsNormalizerUpdate(oldDecimalsNormalizer, newDecimalsNormalizer);
    }

    function _setDecimalsNormalizerFromToken(address token) internal {
        int256 feiDecimals = 18;
        int256 _decimalsNormalizer = feiDecimals - int256(uint256(IERC20Metadata(token).decimals()));

        if (doInvert) {
            _decimalsNormalizer = -1 * _decimalsNormalizer;
        }

        _setDecimalsNormalizer(_decimalsNormalizer);
    }
}

// File: contracts/pcv/IPCVSwapper.sol



// SPDX-License-Identifier: GPL-3.0-or-later
pragma solidity ^0.8.4;

/// @title a PCV Swapper interface
/// @author eswak
interface IPCVSwapper {
    // ----------- Events -----------
    event UpdateReceivingAddress(address oldTokenReceivingAddress, address newTokenReceivingAddress);

    event Swap(
        address indexed _caller,
        address indexed _tokenSpent,
        address indexed _tokenReceived,
        uint256 _amountSpent,
        uint256 _amountReceived
    );

    // ----------- State changing api -----------

    function swap() external;

    // ----------- Governor only state changing api -----------

    function setReceivingAddress(address _tokenReceivingAddress) external;

    // ----------- Getters -----------

    function tokenSpent() external view returns (address);

    function tokenReceived() external view returns (address);

    function tokenReceivingAddress() external view returns (address);
}

// File: @openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC20/utils/SafeERC20.sol)

pragma solidity ^0.8.0;

import "../IERC20.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 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'
        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) + value;
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
    }

    function safeDecreaseAllowance(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        unchecked {
            uint256 oldAllowance = token.allowance(address(this), spender);
            require(oldAllowance >= value, "SafeERC20: decreased allowance below zero");
            uint256 newAllowance = oldAllowance - value;
            _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
            require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
        }
    }
}

// File: contracts/pcv/balancer/manager/IWeightedBalancerPoolManager.sol



// SPDX-License-Identifier: GPL-3.0-or-later
pragma solidity ^0.8.0;

import "../IWeightedPool.sol";
import "./IBaseBalancerPoolManager.sol";

interface IWeightedBalancerPoolManager is IBaseBalancerPoolManager {
    // ----------- Governor or admin only state changing API -----------
    function setSwapEnabled(IWeightedPool pool, bool swapEnabled) external;

    function updateWeightsGradually(
        IWeightedPool pool,
        uint256 startTime,
        uint256 endTime,
        uint256[] memory endWeights
    ) external;

    function withdrawCollectedManagementFees(IWeightedPool pool, address recipient) external;
}

// File: contracts/pcv/balancer/manager/BaseBalancerPoolManager.sol



// SPDX-License-Identifier: GPL-3.0-or-later
pragma solidity ^0.8.0;

import "../../../refs/CoreRef.sol";
import "./IBaseBalancerPoolManager.sol";

/// @title BaseBalancerPoolManager
/// @notice an abstract utility class for a contract that manages a Balancer BasePool
/// exposes the governable methods to Fei Governors or admins
abstract contract BaseBalancerPoolManager is IBaseBalancerPoolManager, CoreRef {
    constructor() {
        _setContractAdminRole(keccak256("BALANCER_MANAGER_ADMIN_ROLE"));
    }

    function setSwapFee(IBasePool pool, uint256 swapFee) public override onlyGovernorOrAdmin {
        pool.setSwapFeePercentage(swapFee);
    }

    function setPaused(IBasePool pool, bool paused) public override onlyGovernorOrAdmin {
        pool.setPaused(paused);
    }

    function setAssetManagerPoolConfig(
        IBasePool pool,
        IERC20 token,
        IAssetManager.PoolConfig memory poolConfig
    ) public override onlyGovernorOrAdmin {
        pool.setAssetManagerPoolConfig(token, poolConfig);
    }
}

// File: contracts/pcv/balancer/IWeightedPool.sol



// SPDX-License-Identifier: GPL-3.0-or-later
pragma solidity ^0.8.0;

import "./IBasePool.sol";

// interface with required methods from Balancer V2 WeightedPool
// https://github.com/balancer-labs/balancer-v2-monorepo/blob/389b52f1fc9e468de854810ce9dc3251d2d5b212/pkg/pool-weighted/contracts/WeightedPool.sol
interface IWeightedPool is IBasePool {
    function getSwapEnabled() external view returns (bool);

    function getNormalizedWeights() external view returns (uint256[] memory);

    function getGradualWeightUpdateParams()
        external
        view
        returns (
            uint256 startTime,
            uint256 endTime,
            uint256[] memory endWeights
        );

    function setSwapEnabled(bool swapEnabled) external;

    function updateWeightsGradually(
        uint256 startTime,
        uint256 endTime,
        uint256[] memory endWeights
    ) external;

    function withdrawCollectedManagementFees(address recipient) external;

    enum JoinKind {
        INIT,
        EXACT_TOKENS_IN_FOR_BPT_OUT,
        TOKEN_IN_FOR_EXACT_BPT_OUT
    }
    enum ExitKind {
        EXACT_BPT_IN_FOR_ONE_TOKEN_OUT,
        EXACT_BPT_IN_FOR_TOKENS_OUT,
        BPT_IN_FOR_EXACT_TOKENS_OUT
    }
}

// File: contracts/pcv/balancer/manager/IBaseBalancerPoolManager.sol



// SPDX-License-Identifier: GPL-3.0-or-later
pragma solidity ^0.8.0;

import "../IBasePool.sol";

interface IBaseBalancerPoolManager {
    // ----------- Governor or admin only state changing API -----------
    function setSwapFee(IBasePool pool, uint256 swapFee) external;

    function setPaused(IBasePool pool, bool paused) external;

    function setAssetManagerPoolConfig(
        IBasePool pool,
        IERC20 token,
        IAssetManager.PoolConfig memory poolConfig
    ) external;
}

// File: contracts/pcv/balancer/IBasePool.sol



// SPDX-License-Identifier: GPL-3.0-or-later
pragma solidity ^0.8.0;

import "./IAssetManager.sol";
import "./IVault.sol";
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";

// interface with required methods from Balancer V2 IBasePool
// https://github.com/balancer-labs/balancer-v2-monorepo/blob/389b52f1fc9e468de854810ce9dc3251d2d5b212/pkg/pool-utils/contracts/BasePool.sol

interface IBasePool is IERC20 {
    function getSwapFeePercentage() external view returns (uint256);

    function setSwapFeePercentage(uint256 swapFeePercentage) external;

    function setAssetManagerPoolConfig(IERC20 token, IAssetManager.PoolConfig memory poolConfig) external;

    function setPaused(bool paused) external;

    function getVault() external view returns (IVault);

    function getPoolId() external view returns (bytes32);

    function getOwner() external view returns (address);
}

// File: contracts/pcv/balancer/IAssetManager.sol



// SPDX-License-Identifier: GPL-3.0-or-later
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

pragma solidity ^0.8.0;

// interface with required methods from Balancer V2 IBasePool
// https://github.com/balancer-labs/balancer-v2-monorepo/blob/389b52f1fc9e468de854810ce9dc3251d2d5b212/pkg/asset-manager-utils/contracts/IAssetManager.sol

interface IAssetManager {
    struct PoolConfig {
        uint64 targetPercentage;
        uint64 criticalPercentage;
        uint64 feePercentage;
    }

    function setPoolConfig(bytes32 poolId, PoolConfig calldata config) external;
}

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



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.6.0) (token/ERC20/IERC20.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}. `value` is the new allowance.
     */
    event Approval(address indexed owner, address indexed spender, uint256 value);

    /**
     * @dev 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 `to`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address to, 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 `from` to `to` 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 from,
        address to,
        uint256 amount
    ) external returns (bool);
}

// File: contracts/refs/CoreRef.sol



// SPDX-License-Identifier: GPL-3.0-or-later
pragma solidity ^0.8.4;

import "./ICoreRef.sol";
import "@openzeppelin/contracts/security/Pausable.sol";

/// @title A Reference to Core
/// @author Fei Protocol
/// @notice defines some modifiers and utilities around interacting with Core
abstract contract CoreRef is ICoreRef, Pausable {
    ICore private immutable _core;
    IFei private immutable _fei;
    IERC20 private immutable _tribe;

    /// @notice a role used with a subset of governor permissions for this contract only
    bytes32 public override CONTRACT_ADMIN_ROLE;

    constructor(address coreAddress) {
        _core = ICore(coreAddress);

        _fei = ICore(coreAddress).fei();
        _tribe = ICore(coreAddress).tribe();

        _setContractAdminRole(ICore(coreAddress).GOVERN_ROLE());
    }

    function _initialize(address) internal {} // no-op for backward compatibility

    modifier ifMinterSelf() {
        if (_core.isMinter(address(this))) {
            _;
        }
    }

    modifier onlyMinter() {
        require(_core.isMinter(msg.sender), "CoreRef: Caller is not a minter");
        _;
    }

    modifier onlyBurner() {
        require(_core.isBurner(msg.sender), "CoreRef: Caller is not a burner");
        _;
    }

    modifier onlyPCVController() {
        require(_core.isPCVController(msg.sender), "CoreRef: Caller is not a PCV controller");
        _;
    }

    modifier onlyGovernorOrAdmin() {
        require(
            _core.isGovernor(msg.sender) || isContractAdmin(msg.sender),
            "CoreRef: Caller is not a governor or contract admin"
        );
        _;
    }

    modifier onlyGovernor() {
        require(_core.isGovernor(msg.sender), "CoreRef: Caller is not a governor");
        _;
    }

    modifier onlyGuardianOrGovernor() {
        require(
            _core.isGovernor(msg.sender) || _core.isGuardian(msg.sender),
            "CoreRef: Caller is not a guardian or governor"
        );
        _;
    }

    modifier isGovernorOrGuardianOrAdmin() {
        require(
            _core.isGovernor(msg.sender) || _core.isGuardian(msg.sender) || isContractAdmin(msg.sender),
            "CoreRef: Caller is not governor or guardian or admin"
        );
        _;
    }

    // Named onlyTribeRole to prevent collision with OZ onlyRole modifier
    modifier onlyTribeRole(bytes32 role) {
        require(_core.hasRole(role, msg.sender), "UNAUTHORIZED");
        _;
    }

    // Modifiers to allow any combination of roles
    modifier hasAnyOfTwoRoles(bytes32 role1, bytes32 role2) {
        require(_core.hasRole(role1, msg.sender) || _core.hasRole(role2, msg.sender), "UNAUTHORIZED");
        _;
    }

    modifier hasAnyOfThreeRoles(
        bytes32 role1,
        bytes32 role2,
        bytes32 role3
    ) {
        require(
            _core.hasRole(role1, msg.sender) || _core.hasRole(role2, msg.sender) || _core.hasRole(role3, msg.sender),
            "UNAUTHORIZED"
        );
        _;
    }

    modifier hasAnyOfFourRoles(
        bytes32 role1,
        bytes32 role2,
        bytes32 role3,
        bytes32 role4
    ) {
        require(
            _core.hasRole(role1, msg.sender) ||
                _core.hasRole(role2, msg.sender) ||
                _core.hasRole(role3, msg.sender) ||
                _core.hasRole(role4, msg.sender),
            "UNAUTHORIZED"
        );
        _;
    }

    modifier hasAnyOfFiveRoles(
        bytes32 role1,
        bytes32 role2,
        bytes32 role3,
        bytes32 role4,
        bytes32 role5
    ) {
        require(
            _core.hasRole(role1, msg.sender) ||
                _core.hasRole(role2, msg.sender) ||
                _core.hasRole(role3, msg.sender) ||
                _core.hasRole(role4, msg.sender) ||
                _core.hasRole(role5, msg.sender),
            "UNAUTHORIZED"
        );
        _;
    }

    modifier hasAnyOfSixRoles(
        bytes32 role1,
        bytes32 role2,
        bytes32 role3,
        bytes32 role4,
        bytes32 role5,
        bytes32 role6
    ) {
        require(
            _core.hasRole(role1, msg.sender) ||
                _core.hasRole(role2, msg.sender) ||
                _core.hasRole(role3, msg.sender) ||
                _core.hasRole(role4, msg.sender) ||
                _core.hasRole(role5, msg.sender) ||
                _core.hasRole(role6, msg.sender),
            "UNAUTHORIZED"
        );
        _;
    }

    modifier onlyFei() {
        require(msg.sender == address(_fei), "CoreRef: Caller is not FEI");
        _;
    }

    /// @notice sets a new admin role for this contract
    function setContractAdminRole(bytes32 newContractAdminRole) external override onlyGovernor {
        _setContractAdminRole(newContractAdminRole);
    }

    /// @notice returns whether a given address has the admin role for this contract
    function isContractAdmin(address _admin) public view override returns (bool) {
        return _core.hasRole(CONTRACT_ADMIN_ROLE, _admin);
    }

    /// @notice set pausable methods to paused
    function pause() public override onlyGuardianOrGovernor {
        _pause();
    }

    /// @notice set pausable methods to unpaused
    function unpause() public override onlyGuardianOrGovernor {
        _unpause();
    }

    /// @notice address of the Core contract referenced
    /// @return ICore implementation address
    function core() public view override returns (ICore) {
        return _core;
    }

    /// @notice address of the Fei contract referenced by Core
    /// @return IFei implementation address
    function fei() public view override returns (IFei) {
        return _fei;
    }

    /// @notice address of the Tribe contract referenced by Core
    /// @return IERC20 implementation address
    function tribe() public view override returns (IERC20) {
        return _tribe;
    }

    /// @notice fei balance of contract
    /// @return fei amount held
    function feiBalance() public view override returns (uint256) {
        return _fei.balanceOf(address(this));
    }

    /// @notice tribe balance of contract
    /// @return tribe amount held
    function tribeBalance() public view override returns (uint256) {
        return _tribe.balanceOf(address(this));
    }

    function _burnFeiHeld() internal {
        _fei.burn(feiBalance());
    }

    function _mintFei(address to, uint256 amount) internal virtual {
        if (amount != 0) {
            _fei.mint(to, amount);
        }
    }

    function _setContractAdminRole(bytes32 newContractAdminRole) internal {
        bytes32 oldContractAdminRole = CONTRACT_ADMIN_ROLE;
        CONTRACT_ADMIN_ROLE = newContractAdminRole;
        emit ContractAdminRoleUpdate(oldContractAdminRole, newContractAdminRole);
    }
}

// File: contracts/refs/ICoreRef.sol



// SPDX-License-Identifier: GPL-3.0-or-later
pragma solidity ^0.8.4;

import "../core/ICore.sol";

/// @title CoreRef interface
/// @author Fei Protocol
interface ICoreRef {
    // ----------- Events -----------

    event CoreUpdate(address indexed oldCore, address indexed newCore);

    event ContractAdminRoleUpdate(bytes32 indexed oldContractAdminRole, bytes32 indexed newContractAdminRole);

    // ----------- Governor only state changing api -----------

    function setContractAdminRole(bytes32 newContractAdminRole) external;

    // ----------- Governor or Guardian only state changing api -----------

    function pause() external;

    function unpause() external;

    // ----------- Getters -----------

    function core() external view returns (ICore);

    function fei() external view returns (IFei);

    function tribe() external view returns (IERC20);

    function feiBalance() external view returns (uint256);

    function tribeBalance() external view returns (uint256);

    function CONTRACT_ADMIN_ROLE() external view returns (bytes32);

    function isContractAdmin(address admin) external view returns (bool);
}

// File: @openzeppelin/contracts/security/Pausable.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (security/Pausable.sol)

pragma solidity ^0.8.0;

import "../utils/Context.sol";

/**
 * @dev Contract module which allows children to implement an emergency stop
 * mechanism that can be triggered by an authorized account.
 *
 * This module is used through inheritance. It will make available the
 * modifiers `whenNotPaused` and `whenPaused`, which can be applied to
 * the functions of your contract. Note that they will not be pausable by
 * simply including this module, only once the modifiers are put in place.
 */
abstract contract Pausable is Context {
    /**
     * @dev Emitted when the pause is triggered by `account`.
     */
    event Paused(address account);

    /**
     * @dev Emitted when the pause is lifted by `account`.
     */
    event Unpaused(address account);

    bool private _paused;

    /**
     * @dev Initializes the contract in unpaused state.
     */
    constructor() {
        _paused = false;
    }

    /**
     * @dev Returns true if the contract is paused, and false otherwise.
     */
    function paused() public view virtual returns (bool) {
        return _paused;
    }

    /**
     * @dev Modifier to make a function callable only when the contract is not paused.
     *
     * Requirements:
     *
     * - The contract must not be paused.
     */
    modifier whenNotPaused() {
        require(!paused(), "Pausable: paused");
        _;
    }

    /**
     * @dev Modifier to make a function callable only when the contract is paused.
     *
     * Requirements:
     *
     * - The contract must be paused.
     */
    modifier whenPaused() {
        require(paused(), "Pausable: not paused");
        _;
    }

    /**
     * @dev Triggers stopped state.
     *
     * Requirements:
     *
     * - The contract must not be paused.
     */
    function _pause() internal virtual whenNotPaused {
        _paused = true;
        emit Paused(_msgSender());
    }

    /**
     * @dev Returns to normal state.
     *
     * Requirements:
     *
     * - The contract must be paused.
     */
    function _unpause() internal virtual whenPaused {
        _paused = false;
        emit Unpaused(_msgSender());
    }
}

// File: contracts/core/ICore.sol



// SPDX-License-Identifier: GPL-3.0-or-later
pragma solidity ^0.8.4;

import "./IPermissions.sol";
import "../fei/IFei.sol";

/// @title Core Interface
/// @author Fei Protocol
interface ICore is IPermissions {
    // ----------- Events -----------

    event FeiUpdate(address indexed _fei);
    event TribeUpdate(address indexed _tribe);
    event GenesisGroupUpdate(address indexed _genesisGroup);
    event TribeAllocation(address indexed _to, uint256 _amount);
    event GenesisPeriodComplete(uint256 _timestamp);

    // ----------- Governor only state changing api -----------

    function init() external;

    // ----------- Governor only state changing api -----------

    function setFei(address token) external;

    function setTribe(address token) external;

    function allocateTribe(address to, uint256 amount) external;

    // ----------- Getters -----------

    function fei() external view returns (IFei);

    function tribe() external view returns (IERC20);
}

// File: contracts/core/IPermissions.sol



// SPDX-License-Identifier: GPL-3.0-or-later
pragma solidity ^0.8.4;

import "@openzeppelin/contracts/access/AccessControl.sol";
import "./IPermissionsRead.sol";

/// @title Permissions interface
/// @author Fei Protocol
interface IPermissions is IAccessControl, IPermissionsRead {
    // ----------- Governor only state changing api -----------

    function createRole(bytes32 role, bytes32 adminRole) external;

    function grantMinter(address minter) external;

    function grantBurner(address burner) external;

    function grantPCVController(address pcvController) external;

    function grantGovernor(address governor) external;

    function grantGuardian(address guardian) external;

    function revokeMinter(address minter) external;

    function revokeBurner(address burner) external;

    function revokePCVController(address pcvController) external;

    function revokeGovernor(address governor) external;

    function revokeGuardian(address guardian) external;

    // ----------- Revoker only state changing api -----------

    function revokeOverride(bytes32 role, address account) external;

    // ----------- Getters -----------

    function GUARDIAN_ROLE() external view returns (bytes32);

    function GOVERN_ROLE() external view returns (bytes32);

    function BURNER_ROLE() external view returns (bytes32);

    function MINTER_ROLE() external view returns (bytes32);

    function PCV_CONTROLLER_ROLE() external view returns (bytes32);
}

// File: contracts/fei/IFei.sol



// SPDX-License-Identifier: GPL-3.0-or-later
pragma solidity ^0.8.4;

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

/// @title FEI stablecoin interface
/// @author Fei Protocol
interface IFei is IERC20 {
    // ----------- Events -----------

    event Minting(address indexed _to, address indexed _minter, uint256 _amount);

    event Burning(address indexed _to, address indexed _burner, uint256 _amount);

    event IncentiveContractUpdate(address indexed _incentivized, address indexed _incentiveContract);

    // ----------- State changing api -----------

    function burn(uint256 amount) external;

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

    // ----------- Burner only state changing api -----------

    function burnFrom(address account, uint256 amount) external;

    // ----------- Minter only state changing api -----------

    function mint(address account, uint256 amount) external;

    // ----------- Governor only state changing api -----------

    function setIncentiveContract(address account, address incentive) external;

    // ----------- Getters -----------

    function incentiveContract(address account) external view returns (address);
}

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



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.6.0) (access/AccessControl.sol)

pragma solidity ^0.8.0;

import "./IAccessControl.sol";
import "../utils/Context.sol";
import "../utils/Strings.sol";
import "../utils/introspection/ERC165.sol";

/**
 * @dev Contract module that allows children to implement role-based access
 * control mechanisms. This is a lightweight version that doesn't allow enumerating role
 * members except through off-chain means by accessing the contract event logs. Some
 * applications may benefit from on-chain enumerability, for those cases see
 * {AccessControlEnumerable}.
 *
 * Roles are referred to by their `bytes32` identifier. These should be exposed
 * in the external API and be unique. The best way to achieve this is by
 * using `public constant` hash digests:
 *
 * ```
 * bytes32 public constant MY_ROLE = keccak256("MY_ROLE");
 * ```
 *
 * Roles can be used to represent a set of permissions. To restrict access to a
 * function call, use {hasRole}:
 *
 * ```
 * function foo() public {
 *     require(hasRole(MY_ROLE, msg.sender));
 *     ...
 * }
 * ```
 *
 * Roles can be granted and revoked dynamically via the {grantRole} and
 * {revokeRole} functions. Each role has an associated admin role, and only
 * accounts that have a role's admin role can call {grantRole} and {revokeRole}.
 *
 * By default, the admin role for all roles is `DEFAULT_ADMIN_ROLE`, which means
 * that only accounts with this role will be able to grant or revoke other
 * roles. More complex role relationships can be created by using
 * {_setRoleAdmin}.
 *
 * WARNING: The `DEFAULT_ADMIN_ROLE` is also its own admin: it has permission to
 * grant and revoke this role. Extra precautions should be taken to secure
 * accounts that have been granted it.
 */
abstract contract AccessControl is Context, IAccessControl, ERC165 {
    struct RoleData {
        mapping(address => bool) members;
        bytes32 adminRole;
    }

    mapping(bytes32 => RoleData) private _roles;

    bytes32 public constant DEFAULT_ADMIN_ROLE = 0x00;

    /**
     * @dev Modifier that checks that an account has a specific role. Reverts
     * with a standardized message including the required role.
     *
     * The format of the revert reason is given by the following regular expression:
     *
     *  /^AccessControl: account (0x[0-9a-f]{40}) is missing role (0x[0-9a-f]{64})$/
     *
     * _Available since v4.1._
     */
    modifier onlyRole(bytes32 role) {
        _checkRole(role);
        _;
    }

    /**
     * @dev See {IERC165-supportsInterface}.
     */
    function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
        return interfaceId == type(IAccessControl).interfaceId || super.supportsInterface(interfaceId);
    }

    /**
     * @dev Returns `true` if `account` has been granted `role`.
     */
    function hasRole(bytes32 role, address account) public view virtual override returns (bool) {
        return _roles[role].members[account];
    }

    /**
     * @dev Revert with a standard message if `_msgSender()` is missing `role`.
     * Overriding this function changes the behavior of the {onlyRole} modifier.
     *
     * Format of the revert message is described in {_checkRole}.
     *
     * _Available since v4.6._
     */
    function _checkRole(bytes32 role) internal view virtual {
        _checkRole(role, _msgSender());
    }

    /**
     * @dev Revert with a standard message if `account` is missing `role`.
     *
     * The format of the revert reason is given by the following regular expression:
     *
     *  /^AccessControl: account (0x[0-9a-f]{40}) is missing role (0x[0-9a-f]{64})$/
     */
    function _checkRole(bytes32 role, address account) internal view virtual {
        if (!hasRole(role, account)) {
            revert(
                string(
                    abi.encodePacked(
                        "AccessControl: account ",
                        Strings.toHexString(uint160(account), 20),
                        " is missing role ",
                        Strings.toHexString(uint256(role), 32)
                    )
                )
            );
        }
    }

    /**
     * @dev Returns the admin role that controls `role`. See {grantRole} and
     * {revokeRole}.
     *
     * To change a role's admin, use {_setRoleAdmin}.
     */
    function getRoleAdmin(bytes32 role) public view virtual override returns (bytes32) {
        return _roles[role].adminRole;
    }

    /**
     * @dev Grants `role` to `account`.
     *
     * If `account` had not been already granted `role`, emits a {RoleGranted}
     * event.
     *
     * Requirements:
     *
     * - the caller must have ``role``'s admin role.
     */
    function grantRole(bytes32 role, address account) public virtual override onlyRole(getRoleAdmin(role)) {
        _grantRole(role, account);
    }

    /**
     * @dev Revokes `role` from `account`.
     *
     * If `account` had been granted `role`, emits a {RoleRevoked} event.
     *
     * Requirements:
     *
     * - the caller must have ``role``'s admin role.
     */
    function revokeRole(bytes32 role, address account) public virtual override onlyRole(getRoleAdmin(role)) {
        _revokeRole(role, account);
    }

    /**
     * @dev Revokes `role` from the calling account.
     *
     * Roles are often managed via {grantRole} and {revokeRole}: this function's
     * purpose is to provide a mechanism for accounts to lose their privileges
     * if they are compromised (such as when a trusted device is misplaced).
     *
     * If the calling account had been revoked `role`, emits a {RoleRevoked}
     * event.
     *
     * Requirements:
     *
     * - the caller must be `account`.
     */
    function renounceRole(bytes32 role, address account) public virtual override {
        require(account == _msgSender(), "AccessControl: can only renounce roles for self");

        _revokeRole(role, account);
    }

    /**
     * @dev Grants `role` to `account`.
     *
     * If `account` had not been already granted `role`, emits a {RoleGranted}
     * event. Note that unlike {grantRole}, this function doesn't perform any
     * checks on the calling account.
     *
     * [WARNING]
     * ====
     * This function should only be called from the constructor when setting
     * up the initial roles for the system.
     *
     * Using this function in any other way is effectively circumventing the admin
     * system imposed by {AccessControl}.
     * ====
     *
     * NOTE: This function is deprecated in favor of {_grantRole}.
     */
    function _setupRole(bytes32 role, address account) internal virtual {
        _grantRole(role, account);
    }

    /**
     * @dev Sets `adminRole` as ``role``'s admin role.
     *
     * Emits a {RoleAdminChanged} event.
     */
    function _setRoleAdmin(bytes32 role, bytes32 adminRole) internal virtual {
        bytes32 previousAdminRole = getRoleAdmin(role);
        _roles[role].adminRole = adminRole;
        emit RoleAdminChanged(role, previousAdminRole, adminRole);
    }

    /**
     * @dev Grants `role` to `account`.
     *
     * Internal function without access restriction.
     */
    function _grantRole(bytes32 role, address account) internal virtual {
        if (!hasRole(role, account)) {
            _roles[role].members[account] = true;
            emit RoleGranted(role, account, _msgSender());
        }
    }

    /**
     * @dev Revokes `role` from `account`.
     *
     * Internal function without access restriction.
     */
    function _revokeRole(bytes32 role, address account) internal virtual {
        if (hasRole(role, account)) {
            _roles[role].members[account] = false;
            emit RoleRevoked(role, account, _msgSender());
        }
    }
}

// File: contracts/core/IPermissionsRead.sol



// SPDX-License-Identifier: GPL-3.0-or-later
pragma solidity ^0.8.4;

/// @title Permissions Read interface
/// @author Fei Protocol
interface IPermissionsRead {
    // ----------- Getters -----------

    function isBurner(address _address) external view returns (bool);

    function isMinter(address _address) external view returns (bool);

    function isGovernor(address _address) external view returns (bool);

    function isGuardian(address _address) external view returns (bool);

    function isPCVController(address _address) external view returns (bool);
}

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



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (access/IAccessControl.sol)

pragma solidity ^0.8.0;

/**
 * @dev External interface of AccessControl declared to support ERC165 detection.
 */
interface IAccessControl {
    /**
     * @dev Emitted when `newAdminRole` is set as ``role``'s admin role, replacing `previousAdminRole`
     *
     * `DEFAULT_ADMIN_ROLE` is the starting admin for all roles, despite
     * {RoleAdminChanged} not being emitted signaling this.
     *
     * _Available since v3.1._
     */
    event RoleAdminChanged(bytes32 indexed role, bytes32 indexed previousAdminRole, bytes32 indexed newAdminRole);

    /**
     * @dev Emitted when `account` is granted `role`.
     *
     * `sender` is the account that originated the contract call, an admin role
     * bearer except when using {AccessControl-_setupRole}.
     */
    event RoleGranted(bytes32 indexed role, address indexed account, address indexed sender);

    /**
     * @dev Emitted when `account` is revoked `role`.
     *
     * `sender` is the account that originated the contract call:
     *   - if using `revokeRole`, it is the admin role bearer
     *   - if using `renounceRole`, it is the role bearer (i.e. `account`)
     */
    event RoleRevoked(bytes32 indexed role, address indexed account, address indexed sender);

    /**
     * @dev Returns `true` if `account` has been granted `role`.
     */
    function hasRole(bytes32 role, address account) external view returns (bool);

    /**
     * @dev Returns the admin role that controls `role`. See {grantRole} and
     * {revokeRole}.
     *
     * To change a role's admin, use {AccessControl-_setRoleAdmin}.
     */
    function getRoleAdmin(bytes32 role) external view returns (bytes32);

    /**
     * @dev Grants `role` to `account`.
     *
     * If `account` had not been already granted `role`, emits a {RoleGranted}
     * event.
     *
     * Requirements:
     *
     * - the caller must have ``role``'s admin role.
     */
    function grantRole(bytes32 role, address account) external;

    /**
     * @dev Revokes `role` from `account`.
     *
     * If `account` had been granted `role`, emits a {RoleRevoked} event.
     *
     * Requirements:
     *
     * - the caller must have ``role``'s admin role.
     */
    function revokeRole(bytes32 role, address account) external;

    /**
     * @dev Revokes `role` from the calling account.
     *
     * Roles are often managed via {grantRole} and {revokeRole}: this function's
     * purpose is to provide a mechanism for accounts to lose their privileges
     * if they are compromised (such as when a trusted device is misplaced).
     *
     * If the calling account had been granted `role`, emits a {RoleRevoked}
     * event.
     *
     * Requirements:
     *
     * - the caller must be `account`.
     */
    function renounceRole(bytes32 role, address account) external;
}

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



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/Context.sol)

pragma solidity ^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 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) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes calldata) {
        return msg.data;
    }
}

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



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/Strings.sol)

pragma solidity ^0.8.0;

/**
 * @dev String operations.
 */
library Strings {
    bytes16 private constant _HEX_SYMBOLS = "0123456789abcdef";

    /**
     * @dev Converts a `uint256` to its ASCII `string` decimal representation.
     */
    function toString(uint256 value) internal pure returns (string memory) {
        // Inspired by OraclizeAPI's implementation - MIT licence
        // https://github.com/oraclize/ethereum-api/blob/b42146b063c7d6ee1358846c198246239e9360e8/oraclizeAPI_0.4.25.sol

        if (value == 0) {
            return "0";
        }
        uint256 temp = value;
        uint256 digits;
        while (temp != 0) {
            digits++;
            temp /= 10;
        }
        bytes memory buffer = new bytes(digits);
        while (value != 0) {
            digits -= 1;
            buffer[digits] = bytes1(uint8(48 + uint256(value % 10)));
            value /= 10;
        }
        return string(buffer);
    }

    /**
     * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation.
     */
    function toHexString(uint256 value) internal pure returns (string memory) {
        if (value == 0) {
            return "0x00";
        }
        uint256 temp = value;
        uint256 length = 0;
        while (temp != 0) {
            length++;
            temp >>= 8;
        }
        return toHexString(value, length);
    }

    /**
     * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation with fixed length.
     */
    function toHexString(uint256 value, uint256 length) internal pure returns (string memory) {
        bytes memory buffer = new bytes(2 * length + 2);
        buffer[0] = "0";
        buffer[1] = "x";
        for (uint256 i = 2 * length + 1; i > 1; --i) {
            buffer[i] = _HEX_SYMBOLS[value & 0xf];
            value >>= 4;
        }
        require(value == 0, "Strings: hex length insufficient");
        return string(buffer);
    }
}

// File: @openzeppelin/contracts/utils/introspection/ERC165.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/introspection/ERC165.sol)

pragma solidity ^0.8.0;

import "./IERC165.sol";

/**
 * @dev Implementation of the {IERC165} interface.
 *
 * Contracts that want to implement ERC165 should inherit from this contract and override {supportsInterface} to check
 * for the additional interface id that will be supported. For example:
 *
 * ```solidity
 * function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
 *     return interfaceId == type(MyInterface).interfaceId || super.supportsInterface(interfaceId);
 * }
 * ```
 *
 * Alternatively, {ERC165Storage} provides an easier to use but more expensive implementation.
 */
abstract contract ERC165 is IERC165 {
    /**
     * @dev See {IERC165-supportsInterface}.
     */
    function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
        return interfaceId == type(IERC165).interfaceId;
    }
}

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



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/introspection/IERC165.sol)

pragma solidity ^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: contracts/refs/IOracleRef.sol



// SPDX-License-Identifier: GPL-3.0-or-later
pragma solidity ^0.8.4;

import "../oracle/IOracle.sol";

/// @title OracleRef interface
/// @author Fei Protocol
interface IOracleRef {
    // ----------- Events -----------

    event OracleUpdate(address indexed oldOracle, address indexed newOracle);

    event InvertUpdate(bool oldDoInvert, bool newDoInvert);

    event DecimalsNormalizerUpdate(int256 oldDecimalsNormalizer, int256 newDecimalsNormalizer);

    event BackupOracleUpdate(address indexed oldBackupOracle, address indexed newBackupOracle);

    // ----------- State changing API -----------

    function updateOracle() external;

    // ----------- Governor only state changing API -----------

    function setOracle(address newOracle) external;

    function setBackupOracle(address newBackupOracle) external;

    function setDecimalsNormalizer(int256 newDecimalsNormalizer) external;

    function setDoInvert(bool newDoInvert) external;

    // ----------- Getters -----------

    function oracle() external view returns (IOracle);

    function backupOracle() external view returns (IOracle);

    function doInvert() external view returns (bool);

    function decimalsNormalizer() external view returns (int256);

    function readOracle() external view returns (Decimal.D256 memory);

    function invert(Decimal.D256 calldata price) external pure returns (Decimal.D256 memory);
}

// File: @openzeppelin/contracts/utils/math/SafeCast.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/math/SafeCast.sol)

pragma solidity ^0.8.0;

/**
 * @dev Wrappers over Solidity's uintXX/intXX casting operators with added overflow
 * checks.
 *
 * Downcasting from uint256/int256 in Solidity does not revert on overflow. This can
 * easily result in undesired exploitation or bugs, since developers usually
 * assume that overflows raise errors. `SafeCast` restores this intuition by
 * reverting the transaction when such 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.
 *
 * Can be combined with {SafeMath} and {SignedSafeMath} to extend it to smaller types, by performing
 * all math on `uint256` and `int256` and then downcasting.
 */
library SafeCast {
    /**
     * @dev Returns the downcasted uint224 from uint256, reverting on
     * overflow (when the input is greater than largest uint224).
     *
     * Counterpart to Solidity's `uint224` operator.
     *
     * Requirements:
     *
     * - input must fit into 224 bits
     */
    function toUint224(uint256 value) internal pure returns (uint224) {
        require(value <= type(uint224).max, "SafeCast: value doesn't fit in 224 bits");
        return uint224(value);
    }

    /**
     * @dev Returns the downcasted uint128 from uint256, reverting on
     * overflow (when the input is greater than largest uint128).
     *
     * Counterpart to Solidity's `uint128` operator.
     *
     * Requirements:
     *
     * - input must fit into 128 bits
     */
    function toUint128(uint256 value) internal pure returns (uint128) {
        require(value <= type(uint128).max, "SafeCast: value doesn't fit in 128 bits");
        return uint128(value);
    }

    /**
     * @dev Returns the downcasted uint96 from uint256, reverting on
     * overflow (when the input is greater than largest uint96).
     *
     * Counterpart to Solidity's `uint96` operator.
     *
     * Requirements:
     *
     * - input must fit into 96 bits
     */
    function toUint96(uint256 value) internal pure returns (uint96) {
        require(value <= type(uint96).max, "SafeCast: value doesn't fit in 96 bits");
        return uint96(value);
    }

    /**
     * @dev Returns the downcasted uint64 from uint256, reverting on
     * overflow (when the input is greater than largest uint64).
     *
     * Counterpart to Solidity's `uint64` operator.
     *
     * Requirements:
     *
     * - input must fit into 64 bits
     */
    function toUint64(uint256 value) internal pure returns (uint64) {
        require(value <= type(uint64).max, "SafeCast: value doesn't fit in 64 bits");
        return uint64(value);
    }

    /**
     * @dev Returns the downcasted uint32 from uint256, reverting on
     * overflow (when the input is greater than largest uint32).
     *
     * Counterpart to Solidity's `uint32` operator.
     *
     * Requirements:
     *
     * - input must fit into 32 bits
     */
    function toUint32(uint256 value) internal pure returns (uint32) {
        require(value <= type(uint32).max, "SafeCast: value doesn't fit in 32 bits");
        return uint32(value);
    }

    /**
     * @dev Returns the downcasted uint16 from uint256, reverting on
     * overflow (when the input is greater than largest uint16).
     *
     * Counterpart to Solidity's `uint16` operator.
     *
     * Requirements:
     *
     * - input must fit into 16 bits
     */
    function toUint16(uint256 value) internal pure returns (uint16) {
        require(value <= type(uint16).max, "SafeCast: value doesn't fit in 16 bits");
        return uint16(value);
    }

    /**
     * @dev Returns the downcasted uint8 from uint256, reverting on
     * overflow (when the input is greater than largest uint8).
     *
     * Counterpart to Solidity's `uint8` operator.
     *
     * Requirements:
     *
     * - input must fit into 8 bits.
     */
    function toUint8(uint256 value) internal pure returns (uint8) {
        require(value <= type(uint8).max, "SafeCast: value doesn't fit in 8 bits");
        return uint8(value);
    }

    /**
     * @dev Converts a signed int256 into an unsigned uint256.
     *
     * Requirements:
     *
     * - input must be greater than or equal to 0.
     */
    function toUint256(int256 value) internal pure returns (uint256) {
        require(value >= 0, "SafeCast: value must be positive");
        return uint256(value);
    }

    /**
     * @dev Returns the downcasted int128 from int256, reverting on
     * overflow (when the input is less than smallest int128 or
     * greater than largest int128).
     *
     * Counterpart to Solidity's `int128` operator.
     *
     * Requirements:
     *
     * - input must fit into 128 bits
     *
     * _Available since v3.1._
     */
    function toInt128(int256 value) internal pure returns (int128) {
        require(value >= type(int128).min && value <= type(int128).max, "SafeCast: value doesn't fit in 128 bits");
        return int128(value);
    }

    /**
     * @dev Returns the downcasted int64 from int256, reverting on
     * overflow (when the input is less than smallest int64 or
     * greater than largest int64).
     *
     * Counterpart to Solidity's `int64` operator.
     *
     * Requirements:
     *
     * - input must fit into 64 bits
     *
     * _Available since v3.1._
     */
    function toInt64(int256 value) internal pure returns (int64) {
        require(value >= type(int64).min && value <= type(int64).max, "SafeCast: value doesn't fit in 64 bits");
        return int64(value);
    }

    /**
     * @dev Returns the downcasted int32 from int256, reverting on
     * overflow (when the input is less than smallest int32 or
     * greater than largest int32).
     *
     * Counterpart to Solidity's `int32` operator.
     *
     * Requirements:
     *
     * - input must fit into 32 bits
     *
     * _Available since v3.1._
     */
    function toInt32(int256 value) internal pure returns (int32) {
        require(value >= type(int32).min && value <= type(int32).max, "SafeCast: value doesn't fit in 32 bits");
        return int32(value);
    }

    /**
     * @dev Returns the downcasted int16 from int256, reverting on
     * overflow (when the input is less than smallest int16 or
     * greater than largest int16).
     *
     * Counterpart to Solidity's `int16` operator.
     *
     * Requirements:
     *
     * - input must fit into 16 bits
     *
     * _Available since v3.1._
     */
    function toInt16(int256 value) internal pure returns (int16) {
        require(value >= type(int16).min && value <= type(int16).max, "SafeCast: value doesn't fit in 16 bits");
        return int16(value);
    }

    /**
     * @dev Returns the downcasted int8 from int256, reverting on
     * overflow (when the input is less than smallest int8 or
     * greater than largest int8).
     *
     * Counterpart to Solidity's `int8` operator.
     *
     * Requirements:
     *
     * - input must fit into 8 bits.
     *
     * _Available since v3.1._
     */
    function toInt8(int256 value) internal pure returns (int8) {
        require(value >= type(int8).min && value <= type(int8).max, "SafeCast: value doesn't fit in 8 bits");
        return int8(value);
    }

    /**
     * @dev Converts an unsigned uint256 into a signed int256.
     *
     * Requirements:
     *
     * - input must be less than or equal to maxInt256.
     */
    function toInt256(uint256 value) internal pure returns (int256) {
        // Note: Unsafe cast below is okay because `type(int256).max` is guaranteed to be positive
        require(value <= uint256(type(int256).max), "SafeCast: value doesn't fit in an int256");
        return int256(value);
    }
}

// File: @openzeppelin/contracts/token/ERC20/extensions/IERC20Metadata.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC20/extensions/IERC20Metadata.sol)

pragma solidity ^0.8.0;

import "../IERC20.sol";

/**
 * @dev Interface for the optional metadata functions from the ERC20 standard.
 *
 * _Available since v4.1._
 */
interface IERC20Metadata is IERC20 {
    /**
     * @dev Returns the name of the token.
     */
    function name() external view returns (string memory);

    /**
     * @dev Returns the symbol of the token.
     */
    function symbol() external view returns (string memory);

    /**
     * @dev Returns the decimals places of the token.
     */
    function decimals() external view returns (uint8);
}

// File: contracts/oracle/IOracle.sol



// SPDX-License-Identifier: GPL-3.0-or-later
pragma solidity ^0.8.4;

import "../external/Decimal.sol";

/// @title generic oracle interface for Fei Protocol
/// @author Fei Protocol
interface IOracle {
    // ----------- Events -----------

    event Update(uint256 _peg);

    // ----------- State changing API -----------

    function update() external;

    // ----------- Getters -----------

    function read() external view returns (Decimal.D256 memory, bool);

    function isOutdated() external view returns (bool);
}

// File: contracts/external/Decimal.sol



/*
    Copyright 2019 dYdX Trading Inc.
    Copyright 2020 Empty Set Squad <emptysetsquad@protonmail.com>
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
    You may obtain a copy of the License at
    http://www.apache.org/licenses/LICENSE-2.0
    Unless required by applicable law or agreed to in writing, software
    distributed under the License is distributed on an "AS IS" BASIS,
    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    See the License for the specific language governing permissions and
    limitations under the License.
*/

pragma solidity ^0.8.4;

import "@openzeppelin/contracts/utils/math/SafeMath.sol";

/**
 * @title Decimal
 * @author dYdX
 *
 * Library that defines a fixed-point number with 18 decimal places.
 */
library Decimal {
    using SafeMath for uint256;

    // ============ Constants ============

    uint256 private constant BASE = 10**18;

    // ============ Structs ============

    struct D256 {
        uint256 value;
    }

    // ============ Static Functions ============

    function zero() internal pure returns (D256 memory) {
        return D256({value: 0});
    }

    function one() internal pure returns (D256 memory) {
        return D256({value: BASE});
    }

    function from(uint256 a) internal pure returns (D256 memory) {
        return D256({value: a.mul(BASE)});
    }

    function ratio(uint256 a, uint256 b) internal pure returns (D256 memory) {
        return D256({value: getPartial(a, BASE, b)});
    }

    // ============ Self Functions ============

    function add(D256 memory self, uint256 b) internal pure returns (D256 memory) {
        return D256({value: self.value.add(b.mul(BASE))});
    }

    function sub(D256 memory self, uint256 b) internal pure returns (D256 memory) {
        return D256({value: self.value.sub(b.mul(BASE))});
    }

    function sub(
        D256 memory self,
        uint256 b,
        string memory reason
    ) internal pure returns (D256 memory) {
        return D256({value: self.value.sub(b.mul(BASE), reason)});
    }

    function mul(D256 memory self, uint256 b) internal pure returns (D256 memory) {
        return D256({value: self.value.mul(b)});
    }

    function div(D256 memory self, uint256 b) internal pure returns (D256 memory) {
        return D256({value: self.value.div(b)});
    }

    function pow(D256 memory self, uint256 b) internal pure returns (D256 memory) {
        if (b == 0) {
            return from(1);
        }

        D256 memory temp = D256({value: self.value});
        for (uint256 i = 1; i < b; i++) {
            temp = mul(temp, self);
        }

        return temp;
    }

    function add(D256 memory self, D256 memory b) internal pure returns (D256 memory) {
        return D256({value: self.value.add(b.value)});
    }

    function sub(D256 memory self, D256 memory b) internal pure returns (D256 memory) {
        return D256({value: self.value.sub(b.value)});
    }

    function sub(
        D256 memory self,
        D256 memory b,
        string memory reason
    ) internal pure returns (D256 memory) {
        return D256({value: self.value.sub(b.value, reason)});
    }

    function mul(D256 memory self, D256 memory b) internal pure returns (D256 memory) {
        return D256({value: getPartial(self.value, b.value, BASE)});
    }

    function div(D256 memory self, D256 memory b) internal pure returns (D256 memory) {
        return D256({value: getPartial(self.value, BASE, b.value)});
    }

    function equals(D256 memory self, D256 memory b) internal pure returns (bool) {
        return self.value == b.value;
    }

    function greaterThan(D256 memory self, D256 memory b) internal pure returns (bool) {
        return compareTo(self, b) == 2;
    }

    function lessThan(D256 memory self, D256 memory b) internal pure returns (bool) {
        return compareTo(self, b) == 0;
    }

    function greaterThanOrEqualTo(D256 memory self, D256 memory b) internal pure returns (bool) {
        return compareTo(self, b) > 0;
    }

    function lessThanOrEqualTo(D256 memory self, D256 memory b) internal pure returns (bool) {
        return compareTo(self, b) < 2;
    }

    function isZero(D256 memory self) internal pure returns (bool) {
        return self.value == 0;
    }

    function asUint256(D256 memory self) internal pure returns (uint256) {
        return self.value.div(BASE);
    }

    // ============ Core Methods ============

    function getPartial(
        uint256 target,
        uint256 numerator,
        uint256 denominator
    ) private pure returns (uint256) {
        return target.mul(numerator).div(denominator);
    }

    function compareTo(D256 memory a, D256 memory b) private pure returns (uint256) {
        if (a.value == b.value) {
            return 1;
        }
        return a.value > b.value ? 2 : 0;
    }
}

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



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.6.0) (utils/math/SafeMath.sol)

pragma solidity ^0.8.0;

// CAUTION
// This version of SafeMath should only be used with Solidity 0.8 or later,
// because it relies on the compiler's built in overflow checks.

/**
 * @dev Wrappers over Solidity's arithmetic operations.
 *
 * NOTE: `SafeMath` is generally not needed starting with Solidity 0.8, since the compiler
 * now has built in overflow checking.
 */
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) {
        unchecked {
            uint256 c = a + b;
            if (c < a) return (false, 0);
            return (true, c);
        }
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function trySub(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            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) {
        unchecked {
            // 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) {
        unchecked {
            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) {
        unchecked {
            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) {
        return a + b;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        return 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) {
        return a * b;
    }

    /**
     * @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.
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        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) {
        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) {
        unchecked {
            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.
     *
     * 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) {
        unchecked {
            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) {
        unchecked {
            require(b > 0, errorMessage);
            return a % b;
        }
    }
}

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



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.5.0) (utils/Address.sol)

pragma solidity ^0.8.1;

/**
 * @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
     * ====
     *
     * [IMPORTANT]
     * ====
     * You shouldn't rely on `isContract` to protect against flash loan attacks!
     *
     * Preventing calls from contracts is highly discouraged. It breaks composability, breaks support for smart wallets
     * like Gnosis Safe, and does not provide security since it can be circumvented by calling from a contract
     * constructor.
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize/address.code.length, which returns 0
        // for contracts in construction, since the code is only stored at the end
        // of the constructor execution.

        return account.code.length > 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");

        (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");

        (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");

        (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");

        (bool success, bytes memory returndata) = target.delegatecall(data);
        return verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Tool to verifies that a low level call was successful, and revert if it wasn't, either by bubbling the
     * revert reason using the provided one.
     *
     * _Available since v4.3._
     */
    function verifyCallResult(
        bool success,
        bytes memory returndata,
        string memory errorMessage
    ) internal 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

                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}