// File: contracts/Comptroller.sol



// SPDX-License-Identifier: BSD-3-Clause
pragma solidity ^0.8.10;

import "./CToken.sol";
import "./ErrorReporter.sol";
import "./PriceOracle.sol";
import "./ComptrollerInterface.sol";
import "./ComptrollerStorage.sol";
import "./Unitroller.sol";
import "./Governance/River.sol";

// import "hardhat/console.sol";

/**
 * @title Compound's Comptroller Contract
 * @author Compound
 */
contract Comptroller is
    ComptrollerV7Storage,
    ComptrollerInterface,
    ComptrollerErrorReporter,
    ExponentialNoError
{
    /// @notice Emitted when an admin supports a market
    event MarketListed(CToken cToken);

    /// @notice Emitted when an account enters a market
    event MarketEntered(CToken cToken, address account);

    /// @notice Emitted when an account exits a market
    event MarketExited(CToken cToken, address account);

    /// @notice Emitted when close factor is changed by admin
    event NewCloseFactor(
        uint oldCloseFactorMantissa,
        uint newCloseFactorMantissa
    );

    /// @notice Emitted when a collateral factor is changed by admin
    event NewCollateralFactor(
        CToken cToken,
        uint oldCollateralFactorMantissa,
        uint newCollateralFactorMantissa
    );

    /// @notice Emitted when liquidation incentive is changed by admin
    event NewLiquidationIncentive(
        uint oldLiquidationIncentiveMantissa,
        uint newLiquidationIncentiveMantissa
    );

    /// @notice Emitted when price oracle is changed
    event NewPriceOracle(
        PriceOracle oldPriceOracle,
        PriceOracle newPriceOracle
    );

    /// @notice Emitted when pause guardian is changed
    event NewPauseGuardian(address oldPauseGuardian, address newPauseGuardian);

    /// @notice Emitted when an action is paused globally
    event ActionPaused(string action, bool pauseState);

    /// @notice Emitted when an action is paused on a market
    event ActionPaused(CToken cToken, string action, bool pauseState);

    /// @notice Emitted when a new borrow-side COMP speed is calculated for a market
    event CompBorrowSpeedUpdated(CToken indexed cToken, uint newSpeed);

    /// @notice Emitted when a new supply-side COMP speed is calculated for a market
    event CompSupplySpeedUpdated(CToken indexed cToken, uint newSpeed);

    /// @notice Emitted when a new COMP speed is set for a contributor
    event ContributorCompSpeedUpdated(
        address indexed contributor,
        uint newSpeed
    );

    /// @notice Emitted when COMP is distributed to a supplier
    event DistributedSupplierComp(
        CToken indexed cToken,
        address indexed supplier,
        uint compDelta,
        uint compSupplyIndex
    );

    /// @notice Emitted when COMP is distributed to a borrower
    event DistributedBorrowerComp(
        CToken indexed cToken,
        address indexed borrower,
        uint compDelta,
        uint compBorrowIndex
    );

    /// @notice Emitted when borrow cap for a cToken is changed
    event NewBorrowCap(CToken indexed cToken, uint newBorrowCap);

    /// @notice Emitted when borrow cap guardian is changed
    event NewBorrowCapGuardian(
        address oldBorrowCapGuardian,
        address newBorrowCapGuardian
    );

    /// @notice Emitted when COMP is granted by admin
    event CompGranted(address recipient, uint amount);

    /// @notice Emitted when COMP accrued for a user has been manually adjusted.
    event CompAccruedAdjusted(
        address indexed user,
        uint oldCompAccrued,
        uint newCompAccrued
    );

    /// @notice Emitted when COMP receivable for a user has been updated.
    event CompReceivableUpdated(
        address indexed user,
        uint oldCompReceivable,
        uint newCompReceivable
    );

    /// @notice The initial COMP index for a market
    uint224 public constant compInitialIndex = 1e36;

    // closeFactorMantissa must be strictly greater than this value
    uint internal constant closeFactorMinMantissa = 0.05e18; // 0.05

    // closeFactorMantissa must not exceed this value
    uint internal constant closeFactorMaxMantissa = 0.9e18; // 0.9

    // No collateralFactorMantissa may exceed this value
    uint internal constant collateralFactorMaxMantissa = 0.97e18; // 0.97

    constructor() {
        admin = msg.sender;
    }

    /*** Assets You Are In ***/

    /**
     * @notice Returns the assets an account has entered
     * @param account The address of the account to pull assets for
     * @return A dynamic list with the assets the account has entered
     */
    function getAssetsIn(
        address account
    ) external view returns (CToken[] memory) {
        CToken[] memory assetsIn = accountAssets[account];

        return assetsIn;
    }

    /**
     * @notice Returns whether the given account is entered in the given asset
     * @param account The address of the account to check
     * @param cToken The cToken to check
     * @return True if the account is in the asset, otherwise false.
     */
    function checkMembership(
        address account,
        CToken cToken
    ) external view returns (bool) {
        return markets[address(cToken)].accountMembership[account];
    }

    /**
     * @notice Add assets to be included in account liquidity calculation
     * @param cTokens The list of addresses of the cToken markets to be enabled
     * @return Success indicator for whether each corresponding market was entered
     */
    function enterMarkets(
        address[] memory cTokens
    ) public override returns (uint[] memory) {
        uint len = cTokens.length;

        uint[] memory results = new uint[](len);
        for (uint i = 0; i < len; i++) {
            CToken cToken = CToken(cTokens[i]);

            results[i] = uint(addToMarketInternal(cToken, msg.sender));
        }

        return results;
    }

    /**
     * @notice Add the market to the borrower's "assets in" for liquidity calculations
     * @param cToken The market to enter
     * @param borrower The address of the account to modify
     * @return Success indicator for whether the market was entered
     */
    function addToMarketInternal(
        CToken cToken,
        address borrower
    ) internal returns (Error) {
        Market storage marketToJoin = markets[address(cToken)];

        if (!marketToJoin.isListed) {
            // market is not listed, cannot join
            return Error.MARKET_NOT_LISTED;
        }

        if (marketToJoin.accountMembership[borrower] == true) {
            // already joined
            return Error.NO_ERROR;
        }

        // survived the gauntlet, add to list
        // NOTE: we store these somewhat redundantly as a significant optimization
        //  this avoids having to iterate through the list for the most common use cases
        //  that is, only when we need to perform liquidity checks
        //  and not whenever we want to check if an account is in a particular market
        marketToJoin.accountMembership[borrower] = true;
        accountAssets[borrower].push(cToken);

        emit MarketEntered(cToken, borrower);

        return Error.NO_ERROR;
    }

    /**
     * @notice Removes asset from sender's account liquidity calculation
     * @dev Sender must not have an outstanding borrow balance in the asset,
     *  or be providing necessary collateral for an outstanding borrow.
     * @param cTokenAddress The address of the asset to be removed
     * @return Whether or not the account successfully exited the market
     */
    function exitMarket(
        address cTokenAddress
    ) external override returns (uint) {
        CToken cToken = CToken(cTokenAddress);
        /* Get sender tokensHeld and amountOwed underlying from the cToken */
        (uint oErr, uint tokensHeld, uint amountOwed, ) = cToken
            .getAccountSnapshot(msg.sender);
        require(oErr == 0, "exitMarket: getAccountSnapshot failed"); // semi-opaque error code

        /* Fail if the sender has a borrow balance */
        if (amountOwed != 0) {
            return
                fail(
                    Error.NONZERO_BORROW_BALANCE,
                    FailureInfo.EXIT_MARKET_BALANCE_OWED
                );
        }

        /* Fail if the sender is not permitted to redeem all of their tokens */
        uint allowed = redeemAllowedInternal(
            cTokenAddress,
            msg.sender,
            tokensHeld
        );
        if (allowed != 0) {
            return
                failOpaque(
                    Error.REJECTION,
                    FailureInfo.EXIT_MARKET_REJECTION,
                    allowed
                );
        }

        Market storage marketToExit = markets[address(cToken)];

        /* Return true if the sender is not already ‘in’ the market */
        if (!marketToExit.accountMembership[msg.sender]) {
            return uint(Error.NO_ERROR);
        }

        /* Set cToken account membership to false */
        delete marketToExit.accountMembership[msg.sender];

        /* Delete cToken from the account’s list of assets */
        // load into memory for faster iteration
        CToken[] memory userAssetList = accountAssets[msg.sender];
        uint len = userAssetList.length;
        uint assetIndex = len;
        for (uint i = 0; i < len; i++) {
            if (userAssetList[i] == cToken) {
                assetIndex = i;
                break;
            }
        }

        // We *must* have found the asset in the list or our redundant data structure is broken
        assert(assetIndex < len);

        // copy last item in list to location of item to be removed, reduce length by 1
        CToken[] storage storedList = accountAssets[msg.sender];
        storedList[assetIndex] = storedList[storedList.length - 1];
        storedList.pop();

        emit MarketExited(cToken, msg.sender);

        return uint(Error.NO_ERROR);
    }

    /*** Policy Hooks ***/

    /**
     * @notice Checks if the account should be allowed to mint tokens in the given market
     * @param cToken The market to verify the mint against
     * @param minter The account which would get the minted tokens
     * @param mintAmount The amount of underlying being supplied to the market in exchange for tokens
     * @return 0 if the mint is allowed, otherwise a semi-opaque error code (See ErrorReporter.sol)
     */
    function mintAllowed(
        address cToken,
        address minter,
        uint mintAmount
    ) external override returns (uint) {
        // Pausing is a very serious situation - we revert to sound the alarms
        require(!mintGuardianPaused[cToken], "mint is paused");

        // Shh - currently unused
        minter;
        mintAmount;

        if (!markets[cToken].isListed) {
            return uint(Error.MARKET_NOT_LISTED);
        }

        // Keep the flywheel moving
        updateCompSupplyIndex(cToken);
        distributeSupplierComp(cToken, minter);

        return uint(Error.NO_ERROR);
    }

    /**
     * @notice Validates mint and reverts on rejection. May emit logs.
     * @param cToken Asset being minted
     * @param minter The address minting the tokens
     * @param actualMintAmount The amount of the underlying asset being minted
     * @param mintTokens The number of tokens being minted
     */
    function mintVerify(
        address cToken,
        address minter,
        uint actualMintAmount,
        uint mintTokens
    ) external override {
        // Shh - currently unused
        cToken;
        minter;
        actualMintAmount;
        mintTokens;

        // Shh - we don't ever want this hook to be marked pure
        if (false) {
            maxAssets = maxAssets;
        }
    }

    /**
     * @notice Checks if the account should be allowed to redeem tokens in the given market
     * @param cToken The market to verify the redeem against
     * @param redeemer The account which would redeem the tokens
     * @param redeemTokens The number of cTokens to exchange for the underlying asset in the market
     * @return 0 if the redeem is allowed, otherwise a semi-opaque error code (See ErrorReporter.sol)
     */
    function redeemAllowed(
        address cToken,
        address redeemer,
        uint redeemTokens
    ) external override returns (uint) {
        uint allowed = redeemAllowedInternal(cToken, redeemer, redeemTokens);
        if (allowed != uint(Error.NO_ERROR)) {
            return allowed;
        }

        // Keep the flywheel moving
        updateCompSupplyIndex(cToken);
        distributeSupplierComp(cToken, redeemer);

        return uint(Error.NO_ERROR);
    }

    function redeemAllowedInternal(
        address cToken,
        address redeemer,
        uint redeemTokens
    ) internal view returns (uint) {
        if (!markets[cToken].isListed) {
            return uint(Error.MARKET_NOT_LISTED);
        }

        /* If the redeemer is not 'in' the market, then we can bypass the liquidity check */
        if (!markets[cToken].accountMembership[redeemer]) {
            return uint(Error.NO_ERROR);
        }

        /* Otherwise, perform a hypothetical liquidity check to guard against shortfall */
        (Error err, , uint shortfall) = getHypotheticalAccountLiquidityInternal(
            redeemer,
            CToken(cToken),
            redeemTokens,
            0
        );
        if (err != Error.NO_ERROR) {
            return uint(err);
        }
        if (shortfall > 0) {
            return uint(Error.INSUFFICIENT_LIQUIDITY);
        }

        return uint(Error.NO_ERROR);
    }

    /**
     * @notice Validates redeem and reverts on rejection. May emit logs.
     * @param cToken Asset being redeemed
     * @param redeemer The address redeeming the tokens
     * @param redeemAmount The amount of the underlying asset being redeemed
     * @param redeemTokens The number of tokens being redeemed
     */
    function redeemVerify(
        address cToken,
        address redeemer,
        uint redeemAmount,
        uint redeemTokens
    ) external override {
        // Shh - currently unused
        cToken;
        redeemer;

        // Require tokens is zero or amount is also zero
        if (redeemTokens == 0 && redeemAmount > 0) {
            revert("redeemTokens zero");
        }
    }

    /**
     * @notice Checks if the account should be allowed to borrow the underlying asset of the given market
     * @param cToken The market to verify the borrow against
     * @param borrower The account which would borrow the asset
     * @param borrowAmount The amount of underlying the account would borrow
     * @return 0 if the borrow is allowed, otherwise a semi-opaque error code (See ErrorReporter.sol)
     */
    function borrowAllowed(
        address cToken,
        address borrower,
        uint borrowAmount
    ) external override returns (uint) {
        // Pausing is a very serious situation - we revert to sound the alarms
        require(!borrowGuardianPaused[cToken], "borrow is paused");

        if (!markets[cToken].isListed) {
            return uint(Error.MARKET_NOT_LISTED);
        }

        if (!markets[cToken].accountMembership[borrower]) {
            // only cTokens may call borrowAllowed if borrower not in market
            require(msg.sender == cToken, "sender must be cToken");

            // attempt to add borrower to the market
            Error err = addToMarketInternal(CToken(msg.sender), borrower);
            if (err != Error.NO_ERROR) {
                return uint(err);
            }

            // it should be impossible to break the important invariant
            assert(markets[cToken].accountMembership[borrower]);
        }

        if (oracle.getUnderlyingPrice(CToken(cToken)) == 0) {
            return uint(Error.PRICE_ERROR);
        }

        uint borrowCap = borrowCaps[cToken];
        // Borrow cap of 0 corresponds to unlimited borrowing
        if (borrowCap != 0) {
            uint totalBorrows = CToken(cToken).totalBorrows();
            uint nextTotalBorrows = add_(totalBorrows, borrowAmount);
            require(nextTotalBorrows < borrowCap, "market borrow cap reached");
        }

        (Error err, , uint shortfall) = getHypotheticalAccountLiquidityInternal(
            borrower,
            CToken(cToken),
            0,
            borrowAmount
        );
        if (err != Error.NO_ERROR) {
            return uint(err);
        }
        if (shortfall > 0) {
            return uint(Error.INSUFFICIENT_LIQUIDITY);
        }

        // Keep the flywheel moving
        Exp memory borrowIndex = Exp({mantissa: CToken(cToken).borrowIndex()});
        updateCompBorrowIndex(cToken, borrowIndex);
        distributeBorrowerComp(cToken, borrower, borrowIndex);

        return uint(Error.NO_ERROR);
    }

    /**
     * @notice Validates borrow and reverts on rejection. May emit logs.
     * @param cToken Asset whose underlying is being borrowed
     * @param borrower The address borrowing the underlying
     * @param borrowAmount The amount of the underlying asset requested to borrow
     */
    function borrowVerify(
        address cToken,
        address borrower,
        uint borrowAmount
    ) external override {
        // Shh - currently unused
        cToken;
        borrower;
        borrowAmount;

        // Shh - we don't ever want this hook to be marked pure
        if (false) {
            maxAssets = maxAssets;
        }
    }

    /**
     * @notice Checks if the account should be allowed to repay a borrow in the given market
     * @param cToken The market to verify the repay against
     * @param payer The account which would repay the asset
     * @param borrower The account which would borrowed the asset
     * @param repayAmount The amount of the underlying asset the account would repay
     * @return 0 if the repay is allowed, otherwise a semi-opaque error code (See ErrorReporter.sol)
     */
    function repayBorrowAllowed(
        address cToken,
        address payer,
        address borrower,
        uint repayAmount
    ) external override returns (uint) {
        // Shh - currently unused
        payer;
        borrower;
        repayAmount;

        if (!markets[cToken].isListed) {
            return uint(Error.MARKET_NOT_LISTED);
        }

        // Keep the flywheel moving
        Exp memory borrowIndex = Exp({mantissa: CToken(cToken).borrowIndex()});
        updateCompBorrowIndex(cToken, borrowIndex);
        distributeBorrowerComp(cToken, borrower, borrowIndex);

        return uint(Error.NO_ERROR);
    }

    /**
     * @notice Validates repayBorrow and reverts on rejection. May emit logs.
     * @param cToken Asset being repaid
     * @param payer The address repaying the borrow
     * @param borrower The address of the borrower
     * @param actualRepayAmount The amount of underlying being repaid
     */
    function repayBorrowVerify(
        address cToken,
        address payer,
        address borrower,
        uint actualRepayAmount,
        uint borrowerIndex
    ) external override {
        // Shh - currently unused
        cToken;
        payer;
        borrower;
        actualRepayAmount;
        borrowerIndex;

        // Shh - we don't ever want this hook to be marked pure
        if (false) {
            maxAssets = maxAssets;
        }
    }

    /**
     * @notice Checks if the liquidation should be allowed to occur
     * @param cTokenBorrowed Asset which was borrowed by the borrower
     * @param cTokenCollateral Asset which was used as collateral and will be seized
     * @param liquidator The address repaying the borrow and seizing the collateral
     * @param borrower The address of the borrower
     * @param repayAmount The amount of underlying being repaid
     */
    function liquidateBorrowAllowed(
        address cTokenBorrowed,
        address cTokenCollateral,
        address liquidator,
        address borrower,
        uint repayAmount
    ) external override returns (uint) {
        // Shh - currently unused
        liquidator;

        if (
            !markets[cTokenBorrowed].isListed ||
            !markets[cTokenCollateral].isListed
        ) {
            return uint(Error.MARKET_NOT_LISTED);
        }

        uint borrowBalance = CToken(cTokenBorrowed).borrowBalanceStored(
            borrower
        );

        /* allow accounts to be liquidated if the market is deprecated */
        if (isDeprecated(CToken(cTokenBorrowed))) {
            require(
                borrowBalance >= repayAmount,
                "Can not repay more than the total borrow"
            );
        } else {
            /* The borrower must have shortfall in order to be liquidatable */
            (Error err, , uint shortfall) = getAccountLiquidityInternal(
                borrower
            );
            if (err != Error.NO_ERROR) {
                return uint(err);
            }

            if (shortfall == 0) {
                return uint(Error.INSUFFICIENT_SHORTFALL);
            }

            /* The liquidator may not repay more than what is allowed by the closeFactor */
            uint maxClose = mul_ScalarTruncate(
                Exp({mantissa: closeFactorMantissa}),
                borrowBalance
            );
            if (repayAmount > maxClose) {
                return uint(Error.TOO_MUCH_REPAY);
            }
        }
        return uint(Error.NO_ERROR);
    }

    /**
     * @notice Validates liquidateBorrow and reverts on rejection. May emit logs.
     * @param cTokenBorrowed Asset which was borrowed by the borrower
     * @param cTokenCollateral Asset which was used as collateral and will be seized
     * @param liquidator The address repaying the borrow and seizing the collateral
     * @param borrower The address of the borrower
     * @param actualRepayAmount The amount of underlying being repaid
     */
    function liquidateBorrowVerify(
        address cTokenBorrowed,
        address cTokenCollateral,
        address liquidator,
        address borrower,
        uint actualRepayAmount,
        uint seizeTokens
    ) external override {
        // Shh - currently unused
        cTokenBorrowed;
        cTokenCollateral;
        liquidator;
        borrower;
        actualRepayAmount;
        seizeTokens;

        // Shh - we don't ever want this hook to be marked pure
        if (false) {
            maxAssets = maxAssets;
        }
    }

    /**
     * @notice Checks if the seizing of assets should be allowed to occur
     * @param cTokenCollateral Asset which was used as collateral and will be seized
     * @param cTokenBorrowed Asset which was borrowed by the borrower
     * @param liquidator The address repaying the borrow and seizing the collateral
     * @param borrower The address of the borrower
     * @param seizeTokens The number of collateral tokens to seize
     */
    function seizeAllowed(
        address cTokenCollateral,
        address cTokenBorrowed,
        address liquidator,
        address borrower,
        uint seizeTokens
    ) external override returns (uint) {
        // Pausing is a very serious situation - we revert to sound the alarms
        require(!seizeGuardianPaused, "seize is paused");

        // Shh - currently unused
        seizeTokens;

        if (
            !markets[cTokenCollateral].isListed ||
            !markets[cTokenBorrowed].isListed
        ) {
            return uint(Error.MARKET_NOT_LISTED);
        }

        if (
            CToken(cTokenCollateral).comptroller() !=
            CToken(cTokenBorrowed).comptroller()
        ) {
            return uint(Error.COMPTROLLER_MISMATCH);
        }

        // Keep the flywheel moving
        updateCompSupplyIndex(cTokenCollateral);
        distributeSupplierComp(cTokenCollateral, borrower);
        distributeSupplierComp(cTokenCollateral, liquidator);

        return uint(Error.NO_ERROR);
    }

    /**
     * @notice Validates seize and reverts on rejection. May emit logs.
     * @param cTokenCollateral Asset which was used as collateral and will be seized
     * @param cTokenBorrowed Asset which was borrowed by the borrower
     * @param liquidator The address repaying the borrow and seizing the collateral
     * @param borrower The address of the borrower
     * @param seizeTokens The number of collateral tokens to seize
     */
    function seizeVerify(
        address cTokenCollateral,
        address cTokenBorrowed,
        address liquidator,
        address borrower,
        uint seizeTokens
    ) external override {
        // Shh - currently unused
        cTokenCollateral;
        cTokenBorrowed;
        liquidator;
        borrower;
        seizeTokens;

        // Shh - we don't ever want this hook to be marked pure
        if (false) {
            maxAssets = maxAssets;
        }
    }

    /**
     * @notice Checks if the account should be allowed to transfer tokens in the given market
     * @param cToken The market to verify the transfer against
     * @param src The account which sources the tokens
     * @param dst The account which receives the tokens
     * @param transferTokens The number of cTokens to transfer
     * @return 0 if the transfer is allowed, otherwise a semi-opaque error code (See ErrorReporter.sol)
     */
    function transferAllowed(
        address cToken,
        address src,
        address dst,
        uint transferTokens
    ) external override returns (uint) {
        // Pausing is a very serious situation - we revert to sound the alarms
        require(!transferGuardianPaused, "transfer is paused");

        // Currently the only consideration is whether or not
        //  the src is allowed to redeem this many tokens
        uint allowed = redeemAllowedInternal(cToken, src, transferTokens);
        if (allowed != uint(Error.NO_ERROR)) {
            return allowed;
        }

        // Keep the flywheel moving
        updateCompSupplyIndex(cToken);
        distributeSupplierComp(cToken, src);
        distributeSupplierComp(cToken, dst);

        return uint(Error.NO_ERROR);
    }

    /**
     * @notice Validates transfer and reverts on rejection. May emit logs.
     * @param cToken Asset being transferred
     * @param src The account which sources the tokens
     * @param dst The account which receives the tokens
     * @param transferTokens The number of cTokens to transfer
     */
    function transferVerify(
        address cToken,
        address src,
        address dst,
        uint transferTokens
    ) external override {
        // Shh - currently unused
        cToken;
        src;
        dst;
        transferTokens;

        // Shh - we don't ever want this hook to be marked pure
        if (false) {
            maxAssets = maxAssets;
        }
    }

    /*** Liquidity/Liquidation Calculations ***/

    /**
     * @dev Local vars for avoiding stack-depth limits in calculating account liquidity.
     *  Note that `cTokenBalance` is the number of cTokens the account owns in the market,
     *  whereas `borrowBalance` is the amount of underlying that the account has borrowed.
     */
    struct AccountLiquidityLocalVars {
        uint sumCollateral;
        uint sumBorrowPlusEffects;
        uint cTokenBalance;
        uint borrowBalance;
        uint exchangeRateMantissa;
        uint oraclePriceMantissa;
        Exp collateralFactor;
        Exp exchangeRate;
        Exp oraclePrice;
        Exp tokensToDenom;
    }

    /**
     * @notice Determine the current account liquidity wrt collateral requirements
     * @return (possible error code (semi-opaque),
                account liquidity in excess of collateral requirements,
     *          account shortfall below collateral requirements)
     */
    function getAccountLiquidity(
        address account
    ) public view returns (uint, uint, uint) {
        (
            Error err,
            uint liquidity,
            uint shortfall
        ) = getHypotheticalAccountLiquidityInternal(
                account,
                CToken(address(0)),
                0,
                0
            );

        return (uint(err), liquidity, shortfall);
    }

    /**
     * @notice Determine the current account liquidity wrt collateral requirements
     * @return (possible error code,
                account liquidity in excess of collateral requirements,
     *          account shortfall below collateral requirements)
     */
    function getAccountLiquidityInternal(
        address account
    ) internal view returns (Error, uint, uint) {
        return
            getHypotheticalAccountLiquidityInternal(
                account,
                CToken(address(0)),
                0,
                0
            );
    }

    /**
     * @notice Determine what the account liquidity would be if the given amounts were redeemed/borrowed
     * @param cTokenModify The market to hypothetically redeem/borrow in
     * @param account The account to determine liquidity for
     * @param redeemTokens The number of tokens to hypothetically redeem
     * @param borrowAmount The amount of underlying to hypothetically borrow
     * @return (possible error code (semi-opaque),
                hypothetical account liquidity in excess of collateral requirements,
     *          hypothetical account shortfall below collateral requirements)
     */
    function getHypotheticalAccountLiquidity(
        address account,
        address cTokenModify,
        uint redeemTokens,
        uint borrowAmount
    ) public view returns (uint, uint, uint) {
        (
            Error err,
            uint liquidity,
            uint shortfall
        ) = getHypotheticalAccountLiquidityInternal(
                account,
                CToken(cTokenModify),
                redeemTokens,
                borrowAmount
            );
        return (uint(err), liquidity, shortfall);
    }

    /**
     * @notice Determine what the account liquidity would be if the given amounts were redeemed/borrowed
     * @param cTokenModify The market to hypothetically redeem/borrow in
     * @param account The account to determine liquidity for
     * @param redeemTokens The number of tokens to hypothetically redeem
     * @param borrowAmount The amount of underlying to hypothetically borrow
     * @dev Note that we calculate the exchangeRateStored for each collateral cToken using stored data,
     *  without calculating accumulated interest.
     * @return (possible error code,
                hypothetical account liquidity in excess of collateral requirements,
     *          hypothetical account shortfall below collateral requirements)
     */
    function getHypotheticalAccountLiquidityInternal(
        address account,
        CToken cTokenModify,
        uint redeemTokens,
        uint borrowAmount
    ) internal view returns (Error, uint, uint) {
        AccountLiquidityLocalVars memory vars; // Holds all our calculation results
        uint oErr;

        // For each asset the account is in
        CToken[] memory assets = accountAssets[account];
        for (uint i = 0; i < assets.length; i++) {
            CToken asset = assets[i];

            // Read the balances and exchange rate from the cToken
            (
                oErr,
                vars.cTokenBalance,
                vars.borrowBalance,
                vars.exchangeRateMantissa
            ) = asset.getAccountSnapshot(account);
            if (oErr != 0) {
                // semi-opaque error code, we assume NO_ERROR == 0 is invariant between upgrades
                return (Error.SNAPSHOT_ERROR, 0, 0);
            }
            vars.collateralFactor = Exp({
                mantissa: markets[address(asset)].collateralFactorMantissa
            });
            vars.exchangeRate = Exp({mantissa: vars.exchangeRateMantissa});

            // Get the normalized price of the asset
            vars.oraclePriceMantissa = oracle.getUnderlyingPrice(asset);
            if (vars.oraclePriceMantissa == 0) {
                return (Error.PRICE_ERROR, 0, 0);
            }
            vars.oraclePrice = Exp({mantissa: vars.oraclePriceMantissa});

            // Pre-compute a conversion factor from tokens -> ether (normalized price value)
            vars.tokensToDenom = mul_(
                mul_(vars.collateralFactor, vars.exchangeRate),
                vars.oraclePrice
            );

            // sumCollateral += tokensToDenom * cTokenBalance
            vars.sumCollateral = mul_ScalarTruncateAddUInt(
                vars.tokensToDenom,
                vars.cTokenBalance,
                vars.sumCollateral
            );

            // sumBorrowPlusEffects += oraclePrice * borrowBalance
            vars.sumBorrowPlusEffects = mul_ScalarTruncateAddUInt(
                vars.oraclePrice,
                vars.borrowBalance,
                vars.sumBorrowPlusEffects
            );

            // Calculate effects of interacting with cTokenModify
            if (asset == cTokenModify) {
                // redeem effect
                // sumBorrowPlusEffects += tokensToDenom * redeemTokens
                vars.sumBorrowPlusEffects = mul_ScalarTruncateAddUInt(
                    vars.tokensToDenom,
                    redeemTokens,
                    vars.sumBorrowPlusEffects
                );

                // borrow effect
                // sumBorrowPlusEffects += oraclePrice * borrowAmount
                vars.sumBorrowPlusEffects = mul_ScalarTruncateAddUInt(
                    vars.oraclePrice,
                    borrowAmount,
                    vars.sumBorrowPlusEffects
                );
            }
        }

        // These are safe, as the underflow condition is checked first
        if (vars.sumCollateral > vars.sumBorrowPlusEffects) {
            return (
                Error.NO_ERROR,
                vars.sumCollateral - vars.sumBorrowPlusEffects,
                0
            );
        } else {
            return (
                Error.NO_ERROR,
                0,
                vars.sumBorrowPlusEffects - vars.sumCollateral
            );
        }
    }

    /**
     * @notice Calculate number of tokens of collateral asset to seize given an underlying amount
     * @dev Used in liquidation (called in cToken.liquidateBorrowFresh)
     * @param cTokenBorrowed The address of the borrowed cToken
     * @param cTokenCollateral The address of the collateral cToken
     * @param actualRepayAmount The amount of cTokenBorrowed underlying to convert into cTokenCollateral tokens
     * @return (errorCode, number of cTokenCollateral tokens to be seized in a liquidation)
     */
    function liquidateCalculateSeizeTokens(
        address cTokenBorrowed,
        address cTokenCollateral,
        uint actualRepayAmount
    ) external view override returns (uint, uint) {
        /* Read oracle prices for borrowed and collateral markets */
        uint priceBorrowedMantissa = oracle.getUnderlyingPrice(
            CToken(cTokenBorrowed)
        );
        uint priceCollateralMantissa = oracle.getUnderlyingPrice(
            CToken(cTokenCollateral)
        );
        if (priceBorrowedMantissa == 0 || priceCollateralMantissa == 0) {
            return (uint(Error.PRICE_ERROR), 0);
        }

        /*
         * Get the exchange rate and calculate the number of collateral tokens to seize:
         *  seizeAmount = actualRepayAmount * liquidationIncentive * priceBorrowed / priceCollateral
         *  seizeTokens = seizeAmount / exchangeRate
         *   = actualRepayAmount * (liquidationIncentive * priceBorrowed) / (priceCollateral * exchangeRate)
         */
        uint exchangeRateMantissa = CToken(cTokenCollateral)
            .exchangeRateStored(); // Note: reverts on error
        uint seizeTokens;
        Exp memory numerator;
        Exp memory denominator;
        Exp memory ratio;

        numerator = mul_(
            Exp({mantissa: liquidationIncentiveMantissa}),
            Exp({mantissa: priceBorrowedMantissa})
        );
        denominator = mul_(
            Exp({mantissa: priceCollateralMantissa}),
            Exp({mantissa: exchangeRateMantissa})
        );
        ratio = div_(numerator, denominator);

        seizeTokens = mul_ScalarTruncate(ratio, actualRepayAmount);

        return (uint(Error.NO_ERROR), seizeTokens);
    }

    /*** Admin Functions ***/

    /**
     * @notice Sets a new price oracle for the comptroller
     * @dev Admin function to set a new price oracle
     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
     */
    function _setPriceOracle(PriceOracle newOracle) public returns (uint) {
        // Check caller is admin
        if (msg.sender != admin) {
            return
                fail(
                    Error.UNAUTHORIZED,
                    FailureInfo.SET_PRICE_ORACLE_OWNER_CHECK
                );
        }

        // Track the old oracle for the comptroller
        PriceOracle oldOracle = oracle;

        // Set comptroller's oracle to newOracle
        oracle = newOracle;

        // Emit NewPriceOracle(oldOracle, newOracle)
        emit NewPriceOracle(oldOracle, newOracle);

        return uint(Error.NO_ERROR);
    }

    /**
     * @notice Sets the closeFactor used when liquidating borrows
     * @dev Admin function to set closeFactor
     * @param newCloseFactorMantissa New close factor, scaled by 1e18
     * @return uint 0=success, otherwise a failure
     */
    function _setCloseFactor(
        uint newCloseFactorMantissa
    ) external returns (uint) {
        // Check caller is admin
        require(msg.sender == admin, "only admin can set close factor");

        require(newCloseFactorMantissa >= closeFactorMinMantissa, "newCloseFactorMantissa below min");
        require(newCloseFactorMantissa <= closeFactorMaxMantissa, "newCloseFactorMantissa exceeds max");

        uint oldCloseFactorMantissa = closeFactorMantissa;
        closeFactorMantissa = newCloseFactorMantissa;
        emit NewCloseFactor(oldCloseFactorMantissa, closeFactorMantissa);

        return uint(Error.NO_ERROR);
    }

    /**
     * @notice Sets the collateralFactor for a market
     * @dev Admin function to set per-market collateralFactor
     * @param cToken The market to set the factor on
     * @param newCollateralFactorMantissa The new collateral factor, scaled by 1e18
     * @return uint 0=success, otherwise a failure. (See ErrorReporter for details)
     */
    function _setCollateralFactor(
        CToken cToken,
        uint newCollateralFactorMantissa
    ) external returns (uint) {
        // Check caller is admin
        if (msg.sender != admin) {
            return
                fail(
                    Error.UNAUTHORIZED,
                    FailureInfo.SET_COLLATERAL_FACTOR_OWNER_CHECK
                );
        }

        // Verify market is listed
        Market storage market = markets[address(cToken)];
        if (!market.isListed) {
            return
                fail(
                    Error.MARKET_NOT_LISTED,
                    FailureInfo.SET_COLLATERAL_FACTOR_NO_EXISTS
                );
        }

        Exp memory newCollateralFactorExp = Exp({
            mantissa: newCollateralFactorMantissa
        });

        // Check collateral factor <= 0.9
        Exp memory highLimit = Exp({mantissa: collateralFactorMaxMantissa});
        if (lessThanExp(highLimit, newCollateralFactorExp)) {
            return
                fail(
                    Error.INVALID_COLLATERAL_FACTOR,
                    FailureInfo.SET_COLLATERAL_FACTOR_VALIDATION
                );
        }

        // If collateral factor != 0, fail if price == 0
        if (
            newCollateralFactorMantissa != 0 &&
            oracle.getUnderlyingPrice(cToken) == 0
        ) {
            return
                fail(
                    Error.PRICE_ERROR,
                    FailureInfo.SET_COLLATERAL_FACTOR_WITHOUT_PRICE
                );
        }

        // Set market's collateral factor to new collateral factor, remember old value
        uint oldCollateralFactorMantissa = market.collateralFactorMantissa;
        market.collateralFactorMantissa = newCollateralFactorMantissa;

        // Emit event with asset, old collateral factor, and new collateral factor
        emit NewCollateralFactor(
            cToken,
            oldCollateralFactorMantissa,
            newCollateralFactorMantissa
        );

        return uint(Error.NO_ERROR);
    }

    /**
     * @notice Sets liquidationIncentive
     * @dev Admin function to set liquidationIncentive
     * @param newLiquidationIncentiveMantissa New liquidationIncentive scaled by 1e18
     * @return uint 0=success, otherwise a failure. (See ErrorReporter for details)
     */
    function _setLiquidationIncentive(
        uint newLiquidationIncentiveMantissa
    ) external returns (uint) {
        // Check caller is admin
        if (msg.sender != admin) {
            return
                fail(
                    Error.UNAUTHORIZED,
                    FailureInfo.SET_LIQUIDATION_INCENTIVE_OWNER_CHECK
                );
        }

        // Save current value for use in log
        uint oldLiquidationIncentiveMantissa = liquidationIncentiveMantissa;

        // Set liquidation incentive to new incentive
        liquidationIncentiveMantissa = newLiquidationIncentiveMantissa;

        // Emit event with old incentive, new incentive
        emit NewLiquidationIncentive(
            oldLiquidationIncentiveMantissa,
            newLiquidationIncentiveMantissa
        );

        return uint(Error.NO_ERROR);
    }

    /**
     * @notice Add the market to the markets mapping and set it as listed
     * @dev Admin function to set isListed and add support for the market
     * @param cToken The address of the market (token) to list
     * @return uint 0=success, otherwise a failure. (See enum Error for details)
     */
    function _supportMarket(CToken cToken) external returns (uint) {
        if (msg.sender != admin) {
            return
                fail(
                    Error.UNAUTHORIZED,
                    FailureInfo.SUPPORT_MARKET_OWNER_CHECK
                );
        }

        if (markets[address(cToken)].isListed) {
            return
                fail(
                    Error.MARKET_ALREADY_LISTED,
                    FailureInfo.SUPPORT_MARKET_EXISTS
                );
        }

        cToken.isCToken(); // Sanity check to make sure its really a CToken

        // Note that isComped is not in active use anymore
        Market storage newMarket = markets[address(cToken)];
        newMarket.isListed = true;
        newMarket.isComped = false;
        newMarket.collateralFactorMantissa = 0;

        _addMarketInternal(address(cToken));
        _initializeMarket(address(cToken));

        emit MarketListed(cToken);

        return uint(Error.NO_ERROR);
    }

    function _addMarketInternal(address cToken) internal {
        for (uint i = 0; i < allMarkets.length; i++) {
            require(allMarkets[i] != CToken(cToken), "market already added");
        }
        allMarkets.push(CToken(cToken));
    }

    function _initializeMarket(address cToken) internal {
        uint32 blockNumber = safe32(
            getBlockNumber(),
            "block number exceeds 32 bits"
        );

        CompMarketState storage supplyState = compSupplyState[cToken];
        CompMarketState storage borrowState = compBorrowState[cToken];

        /*
         * Update market state indices
         */
        if (supplyState.index == 0) {
            // Initialize supply state index with default value
            supplyState.index = compInitialIndex;
        }

        if (borrowState.index == 0) {
            // Initialize borrow state index with default value
            borrowState.index = compInitialIndex;
        }

        /*
         * Update market state block numbers
         */
        supplyState.block = borrowState.block = blockNumber;
    }

    /**
     * @notice Set the given borrow caps for the given cToken markets. Borrowing that brings total borrows to or above borrow cap will revert.
     * @dev Admin or borrowCapGuardian function to set the borrow caps. A borrow cap of 0 corresponds to unlimited borrowing.
     * @param cTokens The addresses of the markets (tokens) to change the borrow caps for
     * @param newBorrowCaps The new borrow cap values in underlying to be set. A value of 0 corresponds to unlimited borrowing.
     */
    function _setMarketBorrowCaps(
        CToken[] calldata cTokens,
        uint[] calldata newBorrowCaps
    ) external {
        require(
            msg.sender == admin || msg.sender == borrowCapGuardian,
            "only admin or borrow cap guardian can set borrow caps"
        );

        uint numMarkets = cTokens.length;
        uint numBorrowCaps = newBorrowCaps.length;

        require(
            numMarkets != 0 && numMarkets == numBorrowCaps,
            "invalid input"
        );

        for (uint i = 0; i < numMarkets; i++) {
            borrowCaps[address(cTokens[i])] = newBorrowCaps[i];
            emit NewBorrowCap(cTokens[i], newBorrowCaps[i]);
        }
    }

    /**
     * @notice Admin function to change the Borrow Cap Guardian
     * @param newBorrowCapGuardian The address of the new Borrow Cap Guardian
     */
    function _setBorrowCapGuardian(address newBorrowCapGuardian) external {
        require(msg.sender == admin, "only admin can set borrow cap guardian");

        // Save current value for inclusion in log
        address oldBorrowCapGuardian = borrowCapGuardian;

        // Store borrowCapGuardian with value newBorrowCapGuardian
        borrowCapGuardian = newBorrowCapGuardian;

        // Emit NewBorrowCapGuardian(OldBorrowCapGuardian, NewBorrowCapGuardian)
        emit NewBorrowCapGuardian(oldBorrowCapGuardian, newBorrowCapGuardian);
    }

    /**
     * @notice Admin function to change the Pause Guardian
     * @param newPauseGuardian The address of the new Pause Guardian
     * @return uint 0=success, otherwise a failure. (See enum Error for details)
     */
    function _setPauseGuardian(address newPauseGuardian) public returns (uint) {
        if (msg.sender != admin) {
            return
                fail(
                    Error.UNAUTHORIZED,
                    FailureInfo.SET_PAUSE_GUARDIAN_OWNER_CHECK
                );
        }

        // Save current value for inclusion in log
        address oldPauseGuardian = pauseGuardian;

        // Store pauseGuardian with value newPauseGuardian
        pauseGuardian = newPauseGuardian;

        // Emit NewPauseGuardian(OldPauseGuardian, NewPauseGuardian)
        emit NewPauseGuardian(oldPauseGuardian, pauseGuardian);

        return uint(Error.NO_ERROR);
    }

    function _setMintPaused(CToken cToken, bool state) public returns (bool) {
        require(
            markets[address(cToken)].isListed,
            "cannot pause a market that is not listed"
        );
        require(
            msg.sender == pauseGuardian || msg.sender == admin,
            "only pause guardian and admin can pause"
        );
        require(msg.sender == admin || state == true, "only admin can unpause");

        mintGuardianPaused[address(cToken)] = state;
        emit ActionPaused(cToken, "Mint", state);
        return state;
    }

    function _setBorrowPaused(CToken cToken, bool state) public returns (bool) {
        require(
            markets[address(cToken)].isListed,
            "cannot pause a market that is not listed"
        );
        require(
            msg.sender == pauseGuardian || msg.sender == admin,
            "only pause guardian and admin can pause"
        );
        require(msg.sender == admin || state == true, "only admin can unpause");

        borrowGuardianPaused[address(cToken)] = state;
        emit ActionPaused(cToken, "Borrow", state);
        return state;
    }

    function _setTransferPaused(bool state) public returns (bool) {
        require(
            msg.sender == pauseGuardian || msg.sender == admin,
            "only pause guardian and admin can pause"
        );
        require(msg.sender == admin || state == true, "only admin can unpause");

        transferGuardianPaused = state;
        emit ActionPaused("Transfer", state);
        return state;
    }

    function _setSeizePaused(bool state) public returns (bool) {
        require(
            msg.sender == pauseGuardian || msg.sender == admin,
            "only pause guardian and admin can pause"
        );
        require(msg.sender == admin || state == true, "only admin can unpause");

        seizeGuardianPaused = state;
        emit ActionPaused("Seize", state);
        return state;
    }

    function _become(Unitroller unitroller) public {
        require(
            msg.sender == unitroller.admin(),
            "only unitroller admin can change brains"
        );
        require(
            unitroller._acceptImplementation() == 0,
            "change not authorized"
        );
    }

    /// @notice Delete this function after proposal 65 is executed
    function fixBadAccruals(
        address[] calldata affectedUsers,
        uint[] calldata amounts
    ) external {
        require(msg.sender == admin, "Only admin can call this function"); // Only the timelock can call this function
        require(
            !proposal65FixExecuted,
            "Already executed this one-off function"
        ); // Require that this function is only called once
        require(affectedUsers.length == amounts.length, "Invalid input");

        // Loop variables
        address user;
        uint currentAccrual;
        uint amountToSubtract;
        uint newAccrual;

        // Iterate through all affected users
        for (uint i = 0; i < affectedUsers.length; ++i) {
            user = affectedUsers[i];
            currentAccrual = compAccrued[user];

            amountToSubtract = amounts[i];

            // The case where the user has claimed and received an incorrect amount of COMP.
            // The user has less currently accrued than the amount they incorrectly received.
            if (amountToSubtract > currentAccrual) {
                // Amount of COMP the user owes the protocol
                uint accountReceivable = amountToSubtract - currentAccrual; // Underflow safe since amountToSubtract > currentAccrual

                uint oldReceivable = compReceivable[user];
                uint newReceivable = add_(oldReceivable, accountReceivable);

                // Accounting: record the COMP debt for the user
                compReceivable[user] = newReceivable;

                emit CompReceivableUpdated(user, oldReceivable, newReceivable);

                amountToSubtract = currentAccrual;
            }

            if (amountToSubtract > 0) {
                // Subtract the bad accrual amount from what they have accrued.
                // Users will keep whatever they have correctly accrued.
                compAccrued[user] = newAccrual = sub_(
                    currentAccrual,
                    amountToSubtract
                );

                emit CompAccruedAdjusted(user, currentAccrual, newAccrual);
            }
        }

        proposal65FixExecuted = true; // Makes it so that this function cannot be called again
    }

    /**
     * @notice Checks caller is admin, or this contract is becoming the new implementation
     */
    function adminOrInitializing() internal view returns (bool) {
        return msg.sender == admin || msg.sender == comptrollerImplementation;
    }

    /*** Comp Distribution ***/

    /**
     * @notice Set COMP speed for a single market
     * @param cToken The market whose COMP speed to update
     * @param supplySpeed New supply-side COMP speed for market
     * @param borrowSpeed New borrow-side COMP speed for market
     */
    function setCompSpeedInternal(
        CToken cToken,
        uint supplySpeed,
        uint borrowSpeed
    ) internal {
        Market storage market = markets[address(cToken)];
        require(market.isListed, "comp market is not listed");

        if (compSupplySpeeds[address(cToken)] != supplySpeed) {
            // Supply speed updated so let's update supply state to ensure that
            //  1. COMP accrued properly for the old speed, and
            //  2. COMP accrued at the new speed starts after this block.
            updateCompSupplyIndex(address(cToken));

            // Update speed and emit event
            compSupplySpeeds[address(cToken)] = supplySpeed;
            emit CompSupplySpeedUpdated(cToken, supplySpeed);
        }

        if (compBorrowSpeeds[address(cToken)] != borrowSpeed) {
            // Borrow speed updated so let's update borrow state to ensure that
            //  1. COMP accrued properly for the old speed, and
            //  2. COMP accrued at the new speed starts after this block.
            Exp memory borrowIndex = Exp({mantissa: cToken.borrowIndex()});
            updateCompBorrowIndex(address(cToken), borrowIndex);

            // Update speed and emit event
            compBorrowSpeeds[address(cToken)] = borrowSpeed;
            emit CompBorrowSpeedUpdated(cToken, borrowSpeed);
        }
    }

    /**
     * @notice Accrue COMP to the market by updating the supply index
     * @param cToken The market whose supply index to update
     * @dev Index is a cumulative sum of the COMP per cToken accrued.
     */
    function updateCompSupplyIndex(address cToken) internal {
        CompMarketState storage supplyState = compSupplyState[cToken];
        uint supplySpeed = compSupplySpeeds[cToken];
        uint32 blockNumber = safe32(
            getBlockNumber(),
            "block number exceeds 32 bits"
        );
        uint deltaBlocks = sub_(uint(blockNumber), uint(supplyState.block));
        if (deltaBlocks > 0 && supplySpeed > 0) {
            // console.log(
            //     "updateCompSupplyIndex: deltaBlocks",
            //     deltaBlocks,
            //     "supplySpeed",
            //     supplySpeed
            // );
            uint supplyTokens = CToken(cToken).totalSupply();
            uint compAccrued = mul_(deltaBlocks, supplySpeed);
            Double memory ratio = supplyTokens > 0
                ? fraction(compAccrued, supplyTokens)
                : Double({mantissa: 0});
            supplyState.index = safe224(
                add_(Double({mantissa: supplyState.index}), ratio).mantissa,
                "new index exceeds 224 bits"
            );
            supplyState.block = blockNumber;
        } else if (deltaBlocks > 0) {
            supplyState.block = blockNumber;
        }
    }

    /**
     * @notice Accrue COMP to the market by updating the borrow index
     * @param cToken The market whose borrow index to update
     * @dev Index is a cumulative sum of the COMP per cToken accrued.
     */
    function updateCompBorrowIndex(
        address cToken,
        Exp memory marketBorrowIndex
    ) internal {
        CompMarketState storage borrowState = compBorrowState[cToken];
        uint borrowSpeed = compBorrowSpeeds[cToken];
        uint32 blockNumber = safe32(
            getBlockNumber(),
            "block number exceeds 32 bits"
        );
        uint deltaBlocks = sub_(uint(blockNumber), uint(borrowState.block));
        if (deltaBlocks > 0 && borrowSpeed > 0) {
            uint borrowAmount = div_(
                CToken(cToken).totalBorrows(),
                marketBorrowIndex
            );
            uint compAccrued = mul_(deltaBlocks, borrowSpeed);
            Double memory ratio = borrowAmount > 0
                ? fraction(compAccrued, borrowAmount)
                : Double({mantissa: 0});
            borrowState.index = safe224(
                add_(Double({mantissa: borrowState.index}), ratio).mantissa,
                "new index exceeds 224 bits"
            );
            borrowState.block = blockNumber;
        } else if (deltaBlocks > 0) {
            borrowState.block = blockNumber;
        }
    }

    /**
     * @notice Calculate COMP accrued by a supplier and possibly transfer it to them
     * @param cToken The market in which the supplier is interacting
     * @param supplier The address of the supplier to distribute COMP to
     */
    function distributeSupplierComp(address cToken, address supplier) internal {
        // TODO: Don't distribute supplier COMP if the user is not in the supplier market.
        // This check should be as gas efficient as possible as distributeSupplierComp is called in many places.
        // - We really don't want to call an external contract as that's quite expensive.

        CompMarketState storage supplyState = compSupplyState[cToken];
        uint supplyIndex = supplyState.index;
        uint supplierIndex = compSupplierIndex[cToken][supplier];

        // Update supplier's index to the current index since we are distributing accrued COMP
        compSupplierIndex[cToken][supplier] = supplyIndex;

        // console.log(
        //     "distributeSupplierComp: supplierIndex",
        //     supplierIndex,
        //     "supplyIndex",
        //     supplyIndex
        // );
        if (supplierIndex == 0 && supplyIndex >= compInitialIndex) {
            // Covers the case where users supplied tokens before the market's supply state index was set.
            // Rewards the user with COMP accrued from the start of when supplier rewards were first
            // set for the market.
            supplierIndex = compInitialIndex;
        }

        // Calculate change in the cumulative sum of the COMP per cToken accrued
        Double memory deltaIndex = Double({
            mantissa: sub_(supplyIndex, supplierIndex)
        });

        // console.log("distributeSupplierComp: deltaIndex", deltaIndex.mantissa);
        uint supplierTokens = CToken(cToken).balanceOf(supplier);

        // Calculate COMP accrued: cTokenAmount * accruedPerCToken
        uint supplierDelta = mul_(supplierTokens, deltaIndex);

        uint supplierAccrued = add_(compAccrued[supplier], supplierDelta);
        compAccrued[supplier] = supplierAccrued;

        // console.log(
        //     "distributeSupplierComp: supplierDelta",
        //     supplierDelta,
        //     "supplierAccrued",
        //     supplierAccrued
        // );
        emit DistributedSupplierComp(
            CToken(cToken),
            supplier,
            supplierDelta,
            supplyIndex
        );
    }

    /**
     * @notice Calculate COMP accrued by a borrower and possibly transfer it to them
     * @dev Borrowers will not begin to accrue until after the first interaction with the protocol.
     * @param cToken The market in which the borrower is interacting
     * @param borrower The address of the borrower to distribute COMP to
     */
    function distributeBorrowerComp(
        address cToken,
        address borrower,
        Exp memory marketBorrowIndex
    ) internal {
        // TODO: Don't distribute supplier COMP if the user is not in the borrower market.
        // This check should be as gas efficient as possible as distributeBorrowerComp is called in many places.
        // - We really don't want to call an external contract as that's quite expensive.

        CompMarketState storage borrowState = compBorrowState[cToken];
        uint borrowIndex = borrowState.index;
        uint borrowerIndex = compBorrowerIndex[cToken][borrower];

        // Update borrowers's index to the current index since we are distributing accrued COMP
        compBorrowerIndex[cToken][borrower] = borrowIndex;

        if (borrowerIndex == 0 && borrowIndex >= compInitialIndex) {
            // Covers the case where users borrowed tokens before the market's borrow state index was set.
            // Rewards the user with COMP accrued from the start of when borrower rewards were first
            // set for the market.
            borrowerIndex = compInitialIndex;
        }

        // Calculate change in the cumulative sum of the COMP per borrowed unit accrued
        Double memory deltaIndex = Double({
            mantissa: sub_(borrowIndex, borrowerIndex)
        });

        uint borrowerAmount = div_(
            CToken(cToken).borrowBalanceStored(borrower),
            marketBorrowIndex
        );

        // Calculate COMP accrued: cTokenAmount * accruedPerBorrowedUnit
        uint borrowerDelta = mul_(borrowerAmount, deltaIndex);

        uint borrowerAccrued = add_(compAccrued[borrower], borrowerDelta);
        compAccrued[borrower] = borrowerAccrued;

        emit DistributedBorrowerComp(
            CToken(cToken),
            borrower,
            borrowerDelta,
            borrowIndex
        );
    }

    /**
     * @notice Calculate additional accrued COMP for a contributor since last accrual
     * @param contributor The address to calculate contributor rewards for
     */
    function updateContributorRewards(address contributor) public {
        uint compSpeed = compContributorSpeeds[contributor];
        uint blockNumber = getBlockNumber();
        uint deltaBlocks = sub_(blockNumber, lastContributorBlock[contributor]);
        if (deltaBlocks > 0 && compSpeed > 0) {
            uint newAccrued = mul_(deltaBlocks, compSpeed);
            uint contributorAccrued = add_(
                compAccrued[contributor],
                newAccrued
            );

            compAccrued[contributor] = contributorAccrued;
            lastContributorBlock[contributor] = blockNumber;
        }
    }

    /**
     * @notice Claim all the comp accrued by holder in all markets
     * @param holder The address to claim COMP for
     */
    function claimComp(address holder) public {
        return claimComp(holder, allMarkets);
    }

    /**
     * @notice Claim all the comp accrued by holder in the specified markets
     * @param holder The address to claim COMP for
     * @param cTokens The list of markets to claim COMP in
     */
    function claimComp(address holder, CToken[] memory cTokens) public {
        address[] memory holders = new address[](1);
        holders[0] = holder;
        claimComp(holders, cTokens, true, true);
    }

    /**
     * @notice Claim all comp accrued by the holders
     * @param holders The addresses to claim COMP for
     * @param cTokens The list of markets to claim COMP in
     * @param borrowers Whether or not to claim COMP earned by borrowing
     * @param suppliers Whether or not to claim COMP earned by supplying
     */
    function claimComp(
        address[] memory holders,
        CToken[] memory cTokens,
        bool borrowers,
        bool suppliers
    ) public {
        for (uint i = 0; i < cTokens.length; i++) {
            CToken cToken = cTokens[i];
            require(markets[address(cToken)].isListed, "market must be listed");
            if (borrowers == true) {
                Exp memory borrowIndex = Exp({mantissa: cToken.borrowIndex()});
                updateCompBorrowIndex(address(cToken), borrowIndex);
                for (uint j = 0; j < holders.length; j++) {
                    distributeBorrowerComp(
                        address(cToken),
                        holders[j],
                        borrowIndex
                    );
                }
            }
            if (suppliers == true) {
                updateCompSupplyIndex(address(cToken));
                for (uint j = 0; j < holders.length; j++) {
                    distributeSupplierComp(address(cToken), holders[j]);
                }
            }
        }
        for (uint j = 0; j < holders.length; j++) {
            compAccrued[holders[j]] = grantCompInternal(
                holders[j],
                compAccrued[holders[j]]
            );
        }
    }

    /**
     * @notice Transfer COMP to the user
     * @dev Note: If there is not enough COMP, we do not perform the transfer all.
     * @param user The address of the user to transfer COMP to
     * @param amount The amount of COMP to (possibly) transfer
     * @return The amount of COMP which was NOT transferred to the user
     */
    function grantCompInternal(
        address user,
        uint amount
    ) internal returns (uint) {
        River comp = River(getCompAddress());
        uint compRemaining = comp.balanceOf(address(this));
        if (amount > 0 && amount <= compRemaining) {
            comp.transfer(user, amount);
            return 0;
        }
        return amount;
    }

    /*** Comp Distribution Admin ***/

    /**
     * @notice Transfer COMP to the recipient
     * @dev Note: If there is not enough COMP, we do not perform the transfer all.
     * @param recipient The address of the recipient to transfer COMP to
     * @param amount The amount of COMP to (possibly) transfer
     */
    function _grantComp(address recipient, uint amount) public {
        require(adminOrInitializing(), "only admin can grant comp");
        uint amountLeft = grantCompInternal(recipient, amount);
        require(amountLeft == 0, "insufficient comp for grant");
        emit CompGranted(recipient, amount);
    }

    /**
     * @notice Set COMP borrow and supply speeds for the specified markets.
     * @param cTokens The markets whose COMP speed to update.
     * @param supplySpeeds New supply-side COMP speed for the corresponding market.
     * @param borrowSpeeds New borrow-side COMP speed for the corresponding market.
     */
    function _setCompSpeeds(
        CToken[] memory cTokens,
        uint[] memory supplySpeeds,
        uint[] memory borrowSpeeds
    ) public {
        require(adminOrInitializing(), "only admin can set comp speed");

        uint numTokens = cTokens.length;
        require(
            numTokens == supplySpeeds.length &&
                numTokens == borrowSpeeds.length,
            "Comptroller::_setCompSpeeds invalid input"
        );

        for (uint i = 0; i < numTokens; ++i) {
            setCompSpeedInternal(cTokens[i], supplySpeeds[i], borrowSpeeds[i]);
        }
    }

    /**
     * @notice Set COMP speed for a single contributor
     * @param contributor The contributor whose COMP speed to update
     * @param compSpeed New COMP speed for contributor
     */
    function _setContributorCompSpeed(
        address contributor,
        uint compSpeed
    ) public {
        require(adminOrInitializing(), "only admin can set comp speed");

        // note that COMP speed could be set to 0 to halt liquidity rewards for a contributor
        updateContributorRewards(contributor);
        if (compSpeed == 0) {
            // release storage
            delete lastContributorBlock[contributor];
        } else {
            lastContributorBlock[contributor] = getBlockNumber();
        }
        compContributorSpeeds[contributor] = compSpeed;

        emit ContributorCompSpeedUpdated(contributor, compSpeed);
    }

    /**
     * @notice Return all of the markets
     * @dev The automatic getter may be used to access an individual market.
     * @return The list of market addresses
     */
    function getAllMarkets() public view returns (CToken[] memory) {
        return allMarkets;
    }

    /**
     * @notice Returns true if the given cToken market has been deprecated
     * @dev All borrows in a deprecated cToken market can be immediately liquidated
     * @param cToken The market to check if deprecated
     */
    function isDeprecated(CToken cToken) public view returns (bool) {
        return
            markets[address(cToken)].collateralFactorMantissa == 0 &&
            borrowGuardianPaused[address(cToken)] == true &&
            cToken.reserveFactorMantissa() == 1e18;
    }

    function getBlockNumber() public view virtual returns (uint) {
        return block.number;
    }

    /**
     * @notice Return the address of the COMP token
     * @return The address of COMP
     */
    function getCompAddress() public view virtual returns (address) {
        // TODO won't relase governance token at this time
        return address(0);
    }
}

// File: contracts/ComptrollerInterface.sol



// SPDX-License-Identifier: BSD-3-Clause
pragma solidity ^0.8.10;

abstract contract ComptrollerInterface {
    /// @notice Indicator that this is a Comptroller contract (for inspection)
    bool public constant isComptroller = true;

    /*** Assets You Are In ***/

    function enterMarkets(
        address[] calldata cTokens
    ) external virtual returns (uint[] memory);

    function exitMarket(address cToken) external virtual returns (uint);

    /*** Policy Hooks ***/

    function mintAllowed(
        address cToken,
        address minter,
        uint mintAmount
    ) external virtual returns (uint);

    function mintVerify(
        address cToken,
        address minter,
        uint mintAmount,
        uint mintTokens
    ) external virtual;

    function redeemAllowed(
        address cToken,
        address redeemer,
        uint redeemTokens
    ) external virtual returns (uint);

    function redeemVerify(
        address cToken,
        address redeemer,
        uint redeemAmount,
        uint redeemTokens
    ) external virtual;

    function borrowAllowed(
        address cToken,
        address borrower,
        uint borrowAmount
    ) external virtual returns (uint);

    function borrowVerify(
        address cToken,
        address borrower,
        uint borrowAmount
    ) external virtual;

    function repayBorrowAllowed(
        address cToken,
        address payer,
        address borrower,
        uint repayAmount
    ) external virtual returns (uint);

    function repayBorrowVerify(
        address cToken,
        address payer,
        address borrower,
        uint repayAmount,
        uint borrowerIndex
    ) external virtual;

    function liquidateBorrowAllowed(
        address cTokenBorrowed,
        address cTokenCollateral,
        address liquidator,
        address borrower,
        uint repayAmount
    ) external virtual returns (uint);

    function liquidateBorrowVerify(
        address cTokenBorrowed,
        address cTokenCollateral,
        address liquidator,
        address borrower,
        uint repayAmount,
        uint seizeTokens
    ) external virtual;

    function seizeAllowed(
        address cTokenCollateral,
        address cTokenBorrowed,
        address liquidator,
        address borrower,
        uint seizeTokens
    ) external virtual returns (uint);

    function seizeVerify(
        address cTokenCollateral,
        address cTokenBorrowed,
        address liquidator,
        address borrower,
        uint seizeTokens
    ) external virtual;

    function transferAllowed(
        address cToken,
        address src,
        address dst,
        uint transferTokens
    ) external virtual returns (uint);

    function transferVerify(
        address cToken,
        address src,
        address dst,
        uint transferTokens
    ) external virtual;

    /*** Liquidity/Liquidation Calculations ***/

    function liquidateCalculateSeizeTokens(
        address cTokenBorrowed,
        address cTokenCollateral,
        uint repayAmount
    ) external view virtual returns (uint, uint);
}

// File: contracts/ComptrollerStorage.sol



// SPDX-License-Identifier: BSD-3-Clause
pragma solidity ^0.8.10;

import "./CToken.sol";
import "./PriceOracle.sol";

contract UnitrollerAdminStorage {
    /**
     * @notice Administrator for this contract
     */
    address public admin;

    /**
     * @notice Pending administrator for this contract
     */
    address public pendingAdmin;

    /**
     * @notice Active brains of Unitroller
     */
    address public comptrollerImplementation;

    /**
     * @notice Pending brains of Unitroller
     */
    address public pendingComptrollerImplementation;
}

contract ComptrollerV1Storage is UnitrollerAdminStorage {
    /**
     * @notice Oracle which gives the price of any given asset
     */
    PriceOracle public oracle;

    /**
     * @notice Multiplier used to calculate the maximum repayAmount when liquidating a borrow
     */
    uint public closeFactorMantissa;

    /**
     * @notice Multiplier representing the discount on collateral that a liquidator receives
     */
    uint public liquidationIncentiveMantissa;

    /**
     * @notice Max number of assets a single account can participate in (borrow or use as collateral)
     */
    uint public maxAssets;

    /**
     * @notice Per-account mapping of "assets you are in", capped by maxAssets
     */
    mapping(address => CToken[]) public accountAssets;
}

contract ComptrollerV2Storage is ComptrollerV1Storage {
    struct Market {
        // Whether or not this market is listed
        bool isListed;
        //  Multiplier representing the most one can borrow against their collateral in this market.
        //  For instance, 0.9 to allow borrowing 90% of collateral value.
        //  Must be between 0 and 1, and stored as a mantissa.
        uint collateralFactorMantissa;
        // Per-market mapping of "accounts in this asset"
        mapping(address => bool) accountMembership;
        // Whether or not this market receives COMP
        bool isComped;
    }

    /**
     * @notice Official mapping of cTokens -> Market metadata
     * @dev Used e.g. to determine if a market is supported
     */
    mapping(address => Market) public markets;

    /**
     * @notice The Pause Guardian can pause certain actions as a safety mechanism.
     *  Actions which allow users to remove their own assets cannot be paused.
     *  Liquidation / seizing / transfer can only be paused globally, not by market.
     */
    address public pauseGuardian;
    bool public _mintGuardianPaused;
    bool public _borrowGuardianPaused;
    bool public transferGuardianPaused;
    bool public seizeGuardianPaused;
    mapping(address => bool) public mintGuardianPaused;
    mapping(address => bool) public borrowGuardianPaused;
}

contract ComptrollerV3Storage is ComptrollerV2Storage {
    struct CompMarketState {
        // The market's last updated compBorrowIndex or compSupplyIndex
        uint224 index;
        // The block number the index was last updated at
        uint32 block;
    }

    /// @notice A list of all markets
    CToken[] public allMarkets;

    /// @notice The rate at which the flywheel distributes COMP, per block
    uint public compRate;

    /// @notice The portion of compRate that each market currently receives
    mapping(address => uint) public compSpeeds;

    /// @notice The COMP market supply state for each market
    mapping(address => CompMarketState) public compSupplyState;

    /// @notice The COMP market borrow state for each market
    mapping(address => CompMarketState) public compBorrowState;

    /// @notice The COMP borrow index for each market for each supplier as of the last time they accrued COMP
    mapping(address => mapping(address => uint)) public compSupplierIndex;

    /// @notice The COMP borrow index for each market for each borrower as of the last time they accrued COMP
    mapping(address => mapping(address => uint)) public compBorrowerIndex;

    /// @notice The COMP accrued but not yet transferred to each user
    mapping(address => uint) public compAccrued;
}

contract ComptrollerV4Storage is ComptrollerV3Storage {
    // @notice The borrowCapGuardian can set borrowCaps to any number for any market. Lowering the borrow cap could disable borrowing on the given market.
    address public borrowCapGuardian;

    // @notice Borrow caps enforced by borrowAllowed for each cToken address. Defaults to zero which corresponds to unlimited borrowing.
    mapping(address => uint) public borrowCaps;
}

contract ComptrollerV5Storage is ComptrollerV4Storage {
    /// @notice The portion of COMP that each contributor receives per block
    mapping(address => uint) public compContributorSpeeds;

    /// @notice Last block at which a contributor's COMP rewards have been allocated
    mapping(address => uint) public lastContributorBlock;
}

contract ComptrollerV6Storage is ComptrollerV5Storage {
    /// @notice The rate at which comp is distributed to the corresponding borrow market (per block)
    mapping(address => uint) public compBorrowSpeeds;

    /// @notice The rate at which comp is distributed to the corresponding supply market (per block)
    mapping(address => uint) public compSupplySpeeds;
}

contract ComptrollerV7Storage is ComptrollerV6Storage {
    /// @notice Flag indicating whether the function to fix COMP accruals has been executed (RE: proposal 62 bug)
    bool public proposal65FixExecuted;

    /// @notice Accounting storage mapping account addresses to how much COMP they owe the protocol.
    mapping(address => uint) public compReceivable;
}

// File: contracts/CToken.sol



// SPDX-License-Identifier: BSD-3-Clause
pragma solidity ^0.8.10;

import "./ComptrollerInterface.sol";
import "./CTokenInterfaces.sol";
import "./ErrorReporter.sol";
import "./EIP20Interface.sol";
import "./InterestRateModel.sol";
import "./ExponentialNoError.sol";

/**
 * @title Compound's CToken Contract
 * @notice Abstract base for CTokens
 * @author Compound
 */
abstract contract CToken is
    CTokenInterface,
    ExponentialNoError,
    TokenErrorReporter
{
    /**
     * @notice Initialize the money market
     * @param comptroller_ The address of the Comptroller
     * @param interestRateModel_ The address of the interest rate model
     * @param initialExchangeRateMantissa_ The initial exchange rate, scaled by 1e18
     * @param name_ EIP-20 name of this token
     * @param symbol_ EIP-20 symbol of this token
     * @param decimals_ EIP-20 decimal precision of this token
     */
    function initialize(
        ComptrollerInterface comptroller_,
        InterestRateModel interestRateModel_,
        uint initialExchangeRateMantissa_,
        string memory name_,
        string memory symbol_,
        uint8 decimals_
    ) public {
        require(msg.sender == admin, "only admin may initialize the market");
        require(
            accrualBlockNumber == 0 && borrowIndex == 0,
            "market may only be initialized once"
        );

        // Set initial exchange rate
        initialExchangeRateMantissa = initialExchangeRateMantissa_;
        require(
            initialExchangeRateMantissa > 0,
            "initial exchange rate must be greater than zero."
        );

        // Set the comptroller
        uint err = _setComptroller(comptroller_);
        require(err == NO_ERROR, "setting comptroller failed");

        // Initialize block number and borrow index (block number mocks depend on comptroller being set)
        accrualBlockNumber = getBlockNumber();
        borrowIndex = mantissaOne;

        // Set the interest rate model (depends on block number / borrow index)
        err = _setInterestRateModelFresh(interestRateModel_);
        require(err == NO_ERROR, "setting interest rate model failed");

        name = name_;
        symbol = symbol_;
        decimals = decimals_;

        // The counter starts true to prevent changing it from zero to non-zero (i.e. smaller cost/refund)
        _notEntered = true;
    }

    /**
     * @notice Transfer `tokens` tokens from `src` to `dst` by `spender`
     * @dev Called by both `transfer` and `transferFrom` internally
     * @param spender The address of the account performing the transfer
     * @param src The address of the source account
     * @param dst The address of the destination account
     * @param tokens The number of tokens to transfer
     * @return 0 if the transfer succeeded, else revert
     */
    function transferTokens(
        address spender,
        address src,
        address dst,
        uint tokens
    ) internal returns (uint) {
        /* Fail if transfer not allowed */
        uint allowed = comptroller.transferAllowed(
            address(this),
            src,
            dst,
            tokens
        );
        if (allowed != 0) {
            revert TransferComptrollerRejection(allowed);
        }

        /* Do not allow self-transfers */
        if (src == dst) {
            revert TransferNotAllowed();
        }

        /* Get the allowance, infinite for the account owner */
        uint startingAllowance = 0;
        if (spender == src) {
            startingAllowance = type(uint).max;
        } else {
            startingAllowance = transferAllowances[src][spender];
        }

        /* Do the calculations, checking for {under,over}flow */
        uint allowanceNew = startingAllowance - tokens;
        uint srcTokensNew = accountTokens[src] - tokens;
        uint dstTokensNew = accountTokens[dst] + tokens;

        /////////////////////////
        // EFFECTS & INTERACTIONS
        // (No safe failures beyond this point)

        accountTokens[src] = srcTokensNew;
        accountTokens[dst] = dstTokensNew;

        /* Eat some of the allowance (if necessary) */
        if (startingAllowance != type(uint).max) {
            transferAllowances[src][spender] = allowanceNew;
        }

        /* We emit a Transfer event */
        emit Transfer(src, dst, tokens);

        // unused function
        // comptroller.transferVerify(address(this), src, dst, tokens);

        return NO_ERROR;
    }

    /**
     * @notice Transfer `amount` tokens from `msg.sender` to `dst`
     * @param dst The address of the destination account
     * @param amount The number of tokens to transfer
     * @return Whether or not the transfer succeeded
     */
    function transfer(
        address dst,
        uint256 amount
    ) external override nonReentrant returns (bool) {
        return transferTokens(msg.sender, msg.sender, dst, amount) == NO_ERROR;
    }

    /**
     * @notice Transfer `amount` tokens from `src` to `dst`
     * @param src The address of the source account
     * @param dst The address of the destination account
     * @param amount The number of tokens to transfer
     * @return Whether or not the transfer succeeded
     */
    function transferFrom(
        address src,
        address dst,
        uint256 amount
    ) external override nonReentrant returns (bool) {
        return transferTokens(msg.sender, src, dst, amount) == NO_ERROR;
    }

    /**
     * @notice Approve `spender` to transfer up to `amount` from `src`
     * @dev This will overwrite the approval amount for `spender`
     *  and is subject to issues noted [here](https://eips.ethereum.org/EIPS/eip-20#approve)
     * @param spender The address of the account which may transfer tokens
     * @param amount The number of tokens that are approved (uint256.max means infinite)
     * @return Whether or not the approval succeeded
     */
    function approve(
        address spender,
        uint256 amount
    ) external override returns (bool) {
        address src = msg.sender;
        transferAllowances[src][spender] = amount;
        emit Approval(src, spender, amount);
        return true;
    }

    /**
     * @notice Get the current allowance from `owner` for `spender`
     * @param owner The address of the account which owns the tokens to be spent
     * @param spender The address of the account which may transfer tokens
     * @return The number of tokens allowed to be spent (-1 means infinite)
     */
    function allowance(
        address owner,
        address spender
    ) external view override returns (uint256) {
        return transferAllowances[owner][spender];
    }

    /**
     * @notice Get the token balance of the `owner`
     * @param owner The address of the account to query
     * @return The number of tokens owned by `owner`
     */
    function balanceOf(address owner) external view override returns (uint256) {
        return accountTokens[owner];
    }

    /**
     * @notice Get the underlying balance of the `owner`
     * @dev This also accrues interest in a transaction
     * @param owner The address of the account to query
     * @return The amount of underlying owned by `owner`
     */
    function balanceOfUnderlying(
        address owner
    ) external override returns (uint) {
        Exp memory exchangeRate = Exp({mantissa: exchangeRateCurrent()});
        return mul_ScalarTruncate(exchangeRate, accountTokens[owner]);
    }

    /**
     * @notice Get a snapshot of the account's balances, and the cached exchange rate
     * @dev This is used by comptroller to more efficiently perform liquidity checks.
     * @param account Address of the account to snapshot
     * @return (possible error, token balance, borrow balance, exchange rate mantissa)
     */
    function getAccountSnapshot(
        address account
    ) external view override returns (uint, uint, uint, uint) {
        return (
            NO_ERROR,
            accountTokens[account],
            borrowBalanceStoredInternal(account),
            exchangeRateStoredInternal()
        );
    }

    /**
     * @dev Function to simply retrieve block number
     *  This exists mainly for inheriting test contracts to stub this result.
     */
    function getBlockNumber() internal view virtual returns (uint) {
        return block.number;
    }

    /**
     * @notice Returns the current per-block borrow interest rate for this cToken
     * @return The borrow interest rate per block, scaled by 1e18
     */
    function borrowRatePerBlock() external view override returns (uint) {
        return
            interestRateModel.getBorrowRate(
                getCashPrior(),
                totalBorrows,
                totalReserves
            );
    }

    /**
     * @notice Returns the current per-block supply interest rate for this cToken
     * @return The supply interest rate per block, scaled by 1e18
     */
    function supplyRatePerBlock() external view override returns (uint) {
        return
            interestRateModel.getSupplyRate(
                getCashPrior(),
                totalBorrows,
                totalReserves,
                reserveFactorMantissa
            );
    }

    /**
     * @notice Returns the current total borrows plus accrued interest
     * @return The total borrows with interest
     */
    function totalBorrowsCurrent()
        external
        override
        nonReentrant
        returns (uint)
    {
        accrueInterest();
        return totalBorrows;
    }

    /**
     * @notice Accrue interest to updated borrowIndex and then calculate account's borrow balance using the updated borrowIndex
     * @param account The address whose balance should be calculated after updating borrowIndex
     * @return The calculated balance
     */
    function borrowBalanceCurrent(
        address account
    ) external override nonReentrant returns (uint) {
        accrueInterest();
        return borrowBalanceStored(account);
    }

    /**
     * @notice Return the borrow balance of account based on stored data
     * @param account The address whose balance should be calculated
     * @return The calculated balance
     */
    function borrowBalanceStored(
        address account
    ) public view override returns (uint) {
        return borrowBalanceStoredInternal(account);
    }

    /**
     * @notice Return the borrow balance of account based on stored data
     * @param account The address whose balance should be calculated
     * @return (error code, the calculated balance or 0 if error code is non-zero)
     */
    function borrowBalanceStoredInternal(
        address account
    ) internal view returns (uint) {
        /* Get borrowBalance and borrowIndex */
        BorrowSnapshot storage borrowSnapshot = accountBorrows[account];

        /* If borrowBalance = 0 then borrowIndex is likely also 0.
         * Rather than failing the calculation with a division by 0, we immediately return 0 in this case.
         */
        if (borrowSnapshot.principal == 0) {
            return 0;
        }

        /* Calculate new borrow balance using the interest index:
         *  recentBorrowBalance = borrower.borrowBalance * market.borrowIndex / borrower.borrowIndex
         */
        uint principalTimesIndex = borrowSnapshot.principal * borrowIndex;
        return principalTimesIndex / borrowSnapshot.interestIndex;
    }

    /**
     * @notice Accrue interest then return the up-to-date exchange rate
     * @return Calculated exchange rate scaled by 1e18
     */
    function exchangeRateCurrent() public override nonReentrant returns (uint) {
        accrueInterest();
        return exchangeRateStored();
    }

    /**
     * @notice Calculates the exchange rate from the underlying to the CToken
     * @dev This function does not accrue interest before calculating the exchange rate
     * @return Calculated exchange rate scaled by 1e18
     */
    function exchangeRateStored() public view override returns (uint) {
        return exchangeRateStoredInternal();
    }

    /**
     * @notice Calculates the exchange rate from the underlying to the CToken
     * @dev This function does not accrue interest before calculating the exchange rate
     * @return calculated exchange rate scaled by 1e18
     */
    function exchangeRateStoredInternal() internal view virtual returns (uint) {
        uint _totalSupply = totalSupply;
        if (_totalSupply == 0) {
            /*
             * If there are no tokens minted:
             *  exchangeRate = initialExchangeRate
             */
            return initialExchangeRateMantissa;
        } else {
            /*
             * Otherwise:
             *  exchangeRate = (totalCash + totalBorrows - totalReserves) / totalSupply
             */
            uint totalCash = getCashPrior();
            uint cashPlusBorrowsMinusReserves = totalCash +
                totalBorrows -
                totalReserves;
            uint exchangeRate = (cashPlusBorrowsMinusReserves * expScale) /
                _totalSupply;

            return exchangeRate;
        }
    }

    /**
     * @notice Get cash balance of this cToken in the underlying asset
     * @return The quantity of underlying asset owned by this contract
     */
    function getCash() external view override returns (uint) {
        return getCashPrior();
    }

    /**
     * @notice Applies accrued interest to total borrows and reserves
     * @dev This calculates interest accrued from the last checkpointed block
     *   up to the current block and writes new checkpoint to storage.
     */
    function accrueInterest() public virtual override returns (uint) {
        /* Remember the initial block number */
        uint currentBlockNumber = getBlockNumber();
        uint accrualBlockNumberPrior = accrualBlockNumber;

        /* Short-circuit accumulating 0 interest */
        if (accrualBlockNumberPrior == currentBlockNumber) {
            return NO_ERROR;
        }

        /* Read the previous values out of storage */
        uint cashPrior = getCashPrior();
        uint borrowsPrior = totalBorrows;
        uint reservesPrior = totalReserves;
        uint borrowIndexPrior = borrowIndex;

        /* Calculate the current borrow interest rate */
        uint borrowRateMantissa = interestRateModel.getBorrowRate(
            cashPrior,
            borrowsPrior,
            reservesPrior
        );
        require(
            borrowRateMantissa <= borrowRateMaxMantissa,
            "borrow rate is absurdly high"
        );

        /* Calculate the number of blocks elapsed since the last accrual */
        uint blockDelta = currentBlockNumber - accrualBlockNumberPrior;

        /*
         * Calculate the interest accumulated into borrows and reserves and the new index:
         *  simpleInterestFactor = borrowRate * blockDelta
         *  interestAccumulated = simpleInterestFactor * totalBorrows
         *  totalBorrowsNew = interestAccumulated + totalBorrows
         *  totalReservesNew = interestAccumulated * reserveFactor + totalReserves
         *  borrowIndexNew = simpleInterestFactor * borrowIndex + borrowIndex
         */

        Exp memory simpleInterestFactor = mul_(
            Exp({mantissa: borrowRateMantissa}),
            blockDelta
        );
        uint interestAccumulated = mul_ScalarTruncate(
            simpleInterestFactor,
            borrowsPrior
        );
        uint totalBorrowsNew = interestAccumulated + borrowsPrior;
        uint totalReservesNew = mul_ScalarTruncateAddUInt(
            Exp({mantissa: reserveFactorMantissa}),
            interestAccumulated,
            reservesPrior
        );
        uint borrowIndexNew = mul_ScalarTruncateAddUInt(
            simpleInterestFactor,
            borrowIndexPrior,
            borrowIndexPrior
        );

        /////////////////////////
        // EFFECTS & INTERACTIONS
        // (No safe failures beyond this point)

        /* We write the previously calculated values into storage */
        accrualBlockNumber = currentBlockNumber;
        borrowIndex = borrowIndexNew;
        totalBorrows = totalBorrowsNew;
        totalReserves = totalReservesNew;

        /* We emit an AccrueInterest event */
        emit AccrueInterest(
            cashPrior,
            interestAccumulated,
            borrowIndexNew,
            totalBorrowsNew
        );

        return NO_ERROR;
    }

    /**
     * @notice Sender supplies assets into the market and receives cTokens in exchange
     * @dev Accrues interest whether or not the operation succeeds, unless reverted
     * @param mintAmount The amount of the underlying asset to supply
     */
    function mintInternal(uint mintAmount) internal nonReentrant {
        accrueInterest();
        // mintFresh emits the actual Mint event if successful and logs on errors, so we don't need to
        mintFresh(msg.sender, mintAmount);
    }

    /**
     * @notice User supplies assets into the market and receives cTokens in exchange
     * @dev Assumes interest has already been accrued up to the current block
     * @param minter The address of the account which is supplying the assets
     * @param mintAmount The amount of the underlying asset to supply
     */
    function mintFresh(address minter, uint mintAmount) internal {
        /* Fail if mint not allowed */
        uint allowed = comptroller.mintAllowed(
            address(this),
            minter,
            mintAmount
        );
        if (allowed != 0) {
            revert MintComptrollerRejection(allowed);
        }

        /* Verify market's block number equals current block number */
        if (accrualBlockNumber != getBlockNumber()) {
            revert MintFreshnessCheck();
        }

        Exp memory exchangeRate = Exp({mantissa: exchangeRateStoredInternal()});

        /////////////////////////
        // EFFECTS & INTERACTIONS
        // (No safe failures beyond this point)

        /*
         *  We call `doTransferIn` for the minter and the mintAmount.
         *  Note: The cToken must handle variations between ERC-20 and ETH underlying.
         *  `doTransferIn` reverts if anything goes wrong, since we can't be sure if
         *  side-effects occurred. The function returns the amount actually transferred,
         *  in case of a fee. On success, the cToken holds an additional `actualMintAmount`
         *  of cash.
         */
        uint actualMintAmount = doTransferIn(minter, mintAmount);

        /*
         * We get the current exchange rate and calculate the number of cTokens to be minted:
         *  mintTokens = actualMintAmount / exchangeRate
         */

        uint mintTokens = div_(actualMintAmount, exchangeRate);

        /*
         * We calculate the new total supply of cTokens and minter token balance, checking for overflow:
         *  totalSupplyNew = totalSupply + mintTokens
         *  accountTokensNew = accountTokens[minter] + mintTokens
         * And write them into storage
         */
        totalSupply = totalSupply + mintTokens;
        accountTokens[minter] = accountTokens[minter] + mintTokens;

        /* We emit a Mint event, and a Transfer event */
        emit Mint(minter, actualMintAmount, mintTokens);
        emit Transfer(address(this), minter, mintTokens);

        /* We call the defense hook */
        // unused function
        // comptroller.mintVerify(address(this), minter, actualMintAmount, mintTokens);
    }

    /**
     * @notice Sender redeems cTokens in exchange for the underlying asset
     * @dev Accrues interest whether or not the operation succeeds, unless reverted
     * @param redeemTokens The number of cTokens to redeem into underlying
     */
    function redeemInternal(uint redeemTokens) internal nonReentrant {
        accrueInterest();
        // redeemFresh emits redeem-specific logs on errors, so we don't need to
        redeemFresh(payable(msg.sender), redeemTokens, 0);
    }

    /**
     * @notice Sender redeems cTokens in exchange for a specified amount of underlying asset
     * @dev Accrues interest whether or not the operation succeeds, unless reverted
     * @param redeemAmount The amount of underlying to receive from redeeming cTokens
     */
    function redeemUnderlyingInternal(uint redeemAmount) internal nonReentrant {
        accrueInterest();
        // redeemFresh emits redeem-specific logs on errors, so we don't need to
        redeemFresh(payable(msg.sender), 0, redeemAmount);
    }

    /**
     * @notice User redeems cTokens in exchange for the underlying asset
     * @dev Assumes interest has already been accrued up to the current block
     * @param redeemer The address of the account which is redeeming the tokens
     * @param redeemTokensIn The number of cTokens to redeem into underlying (only one of redeemTokensIn or redeemAmountIn may be non-zero)
     * @param redeemAmountIn The number of underlying tokens to receive from redeeming cTokens (only one of redeemTokensIn or redeemAmountIn may be non-zero)
     */
    function redeemFresh(
        address payable redeemer,
        uint redeemTokensIn,
        uint redeemAmountIn
    ) internal {
        require(
            redeemTokensIn == 0 || redeemAmountIn == 0,
            "one of redeemTokensIn or redeemAmountIn must be zero"
        );

        /* exchangeRate = invoke Exchange Rate Stored() */
        Exp memory exchangeRate = Exp({mantissa: exchangeRateStoredInternal()});

        uint redeemTokens;
        uint redeemAmount;
        /* If redeemTokensIn > 0: */
        if (redeemTokensIn > 0) {
            /*
             * We calculate the exchange rate and the amount of underlying to be redeemed:
             *  redeemTokens = redeemTokensIn
             *  redeemAmount = redeemTokensIn x exchangeRateCurrent
             */
            redeemTokens = redeemTokensIn;
            redeemAmount = mul_ScalarTruncate(exchangeRate, redeemTokensIn);
        } else {
            /*
             * We get the current exchange rate and calculate the amount to be redeemed:
             *  redeemTokens = redeemAmountIn / exchangeRate
             *  redeemAmount = redeemAmountIn
             */
            redeemTokens = div_(redeemAmountIn, exchangeRate);
            redeemAmount = redeemAmountIn;
        }

        /* Fail if redeem not allowed */
        uint allowed = comptroller.redeemAllowed(
            address(this),
            redeemer,
            redeemTokens
        );
        if (allowed != 0) {
            revert RedeemComptrollerRejection(allowed);
        }

        /* Verify market's block number equals current block number */
        if (accrualBlockNumber != getBlockNumber()) {
            revert RedeemFreshnessCheck();
        }

        /* Fail gracefully if protocol has insufficient cash */
        if (getCashPrior() < redeemAmount) {
            revert RedeemTransferOutNotPossible();
        }

        /////////////////////////
        // EFFECTS & INTERACTIONS
        // (No safe failures beyond this point)

        /*
         * We write the previously calculated values into storage.
         *  Note: Avoid token reentrancy attacks by writing reduced supply before external transfer.
         */
        totalSupply = totalSupply - redeemTokens;
        accountTokens[redeemer] = accountTokens[redeemer] - redeemTokens;

        /*
         * We invoke doTransferOut for the redeemer and the redeemAmount.
         *  Note: The cToken must handle variations between ERC-20 and ETH underlying.
         *  On success, the cToken has redeemAmount less of cash.
         *  doTransferOut reverts if anything goes wrong, since we can't be sure if side effects occurred.
         */
        doTransferOut(redeemer, redeemAmount);

        /* We emit a Transfer event, and a Redeem event */
        emit Transfer(redeemer, address(this), redeemTokens);
        emit Redeem(redeemer, redeemAmount, redeemTokens);

        /* We call the defense hook */
        comptroller.redeemVerify(
            address(this),
            redeemer,
            redeemAmount,
            redeemTokens
        );
    }

    /**
     * @notice Sender borrows assets from the protocol to their own address
     * @param borrowAmount The amount of the underlying asset to borrow
     */
    function borrowInternal(uint borrowAmount) internal nonReentrant {
        accrueInterest();
        // borrowFresh emits borrow-specific logs on errors, so we don't need to
        borrowFresh(payable(msg.sender), borrowAmount);
    }

    /**
     * @notice Users borrow assets from the protocol to their own address
     * @param borrowAmount The amount of the underlying asset to borrow
     */
    function borrowFresh(address payable borrower, uint borrowAmount) internal {
        /* Fail if borrow not allowed */
        uint allowed = comptroller.borrowAllowed(
            address(this),
            borrower,
            borrowAmount
        );
        if (allowed != 0) {
            revert BorrowComptrollerRejection(allowed);
        }

        /* Verify market's block number equals current block number */
        if (accrualBlockNumber != getBlockNumber()) {
            revert BorrowFreshnessCheck();
        }

        /* Fail gracefully if protocol has insufficient underlying cash */
        if (getCashPrior() < borrowAmount) {
            revert BorrowCashNotAvailable();
        }

        /*
         * We calculate the new borrower and total borrow balances, failing on overflow:
         *  accountBorrowNew = accountBorrow + borrowAmount
         *  totalBorrowsNew = totalBorrows + borrowAmount
         */
        uint accountBorrowsPrev = borrowBalanceStoredInternal(borrower);
        uint accountBorrowsNew = accountBorrowsPrev + borrowAmount;
        uint totalBorrowsNew = totalBorrows + borrowAmount;

        /////////////////////////
        // EFFECTS & INTERACTIONS
        // (No safe failures beyond this point)

        /*
         * We write the previously calculated values into storage.
         *  Note: Avoid token reentrancy attacks by writing increased borrow before external transfer.
        `*/
        accountBorrows[borrower].principal = accountBorrowsNew;
        accountBorrows[borrower].interestIndex = borrowIndex;
        totalBorrows = totalBorrowsNew;

        /*
         * We invoke doTransferOut for the borrower and the borrowAmount.
         *  Note: The cToken must handle variations between ERC-20 and ETH underlying.
         *  On success, the cToken borrowAmount less of cash.
         *  doTransferOut reverts if anything goes wrong, since we can't be sure if side effects occurred.
         */
        doTransferOut(borrower, borrowAmount);

        /* We emit a Borrow event */
        emit Borrow(borrower, borrowAmount, accountBorrowsNew, totalBorrowsNew);
    }

    /**
     * @notice Sender repays their own borrow
     * @param repayAmount The amount to repay, or -1 for the full outstanding amount
     */
    function repayBorrowInternal(uint repayAmount) internal nonReentrant {
        accrueInterest();
        // repayBorrowFresh emits repay-borrow-specific logs on errors, so we don't need to
        repayBorrowFresh(msg.sender, msg.sender, repayAmount);
    }

    /**
     * @notice Sender repays a borrow belonging to borrower
     * @param borrower the account with the debt being payed off
     * @param repayAmount The amount to repay, or -1 for the full outstanding amount
     */
    function repayBorrowBehalfInternal(
        address borrower,
        uint repayAmount
    ) internal nonReentrant {
        accrueInterest();
        // repayBorrowFresh emits repay-borrow-specific logs on errors, so we don't need to
        repayBorrowFresh(msg.sender, borrower, repayAmount);
    }

    /**
     * @notice Borrows are repaid by another user (possibly the borrower).
     * @param payer the account paying off the borrow
     * @param borrower the account with the debt being payed off
     * @param repayAmount the amount of underlying tokens being returned, or -1 for the full outstanding amount
     * @return (uint) the actual repayment amount.
     */
    function repayBorrowFresh(
        address payer,
        address borrower,
        uint repayAmount
    ) internal returns (uint) {
        /* Fail if repayBorrow not allowed */
        uint allowed = comptroller.repayBorrowAllowed(
            address(this),
            payer,
            borrower,
            repayAmount
        );
        if (allowed != 0) {
            revert RepayBorrowComptrollerRejection(allowed);
        }

        /* Verify market's block number equals current block number */
        if (accrualBlockNumber != getBlockNumber()) {
            revert RepayBorrowFreshnessCheck();
        }

        /* We fetch the amount the borrower owes, with accumulated interest */
        uint accountBorrowsPrev = borrowBalanceStoredInternal(borrower);

        /* If repayAmount == -1, repayAmount = accountBorrows */
        uint repayAmountFinal = repayAmount == type(uint).max
            ? accountBorrowsPrev
            : repayAmount;

        /////////////////////////
        // EFFECTS & INTERACTIONS
        // (No safe failures beyond this point)

        /*
         * We call doTransferIn for the payer and the repayAmount
         *  Note: The cToken must handle variations between ERC-20 and ETH underlying.
         *  On success, the cToken holds an additional repayAmount of cash.
         *  doTransferIn reverts if anything goes wrong, since we can't be sure if side effects occurred.
         *   it returns the amount actually transferred, in case of a fee.
         */
        uint actualRepayAmount = doTransferIn(payer, repayAmountFinal);

        /*
         * We calculate the new borrower and total borrow balances, failing on underflow:
         *  accountBorrowsNew = accountBorrows - actualRepayAmount
         *  totalBorrowsNew = totalBorrows - actualRepayAmount
         */
        uint accountBorrowsNew = accountBorrowsPrev - actualRepayAmount;
        uint totalBorrowsNew = totalBorrows - actualRepayAmount;

        /* We write the previously calculated values into storage */
        accountBorrows[borrower].principal = accountBorrowsNew;
        accountBorrows[borrower].interestIndex = borrowIndex;
        totalBorrows = totalBorrowsNew;

        /* We emit a RepayBorrow event */
        emit RepayBorrow(
            payer,
            borrower,
            actualRepayAmount,
            accountBorrowsNew,
            totalBorrowsNew
        );

        return actualRepayAmount;
    }

    /**
     * @notice The sender liquidates the borrowers collateral.
     *  The collateral seized is transferred to the liquidator.
     * @param borrower The borrower of this cToken to be liquidated
     * @param cTokenCollateral The market in which to seize collateral from the borrower
     * @param repayAmount The amount of the underlying borrowed asset to repay
     */
    function liquidateBorrowInternal(
        address borrower,
        uint repayAmount,
        CTokenInterface cTokenCollateral
    ) internal nonReentrant {
        accrueInterest();

        uint error = cTokenCollateral.accrueInterest();
        if (error != NO_ERROR) {
            // accrueInterest emits logs on errors, but we still want to log the fact that an attempted liquidation failed
            revert LiquidateAccrueCollateralInterestFailed(error);
        }

        // liquidateBorrowFresh emits borrow-specific logs on errors, so we don't need to
        liquidateBorrowFresh(
            msg.sender,
            borrower,
            repayAmount,
            cTokenCollateral
        );
    }

    /**
     * @notice The liquidator liquidates the borrowers collateral.
     *  The collateral seized is transferred to the liquidator.
     * @param borrower The borrower of this cToken to be liquidated
     * @param liquidator The address repaying the borrow and seizing collateral
     * @param cTokenCollateral The market in which to seize collateral from the borrower
     * @param repayAmount The amount of the underlying borrowed asset to repay
     */
    function liquidateBorrowFresh(
        address liquidator,
        address borrower,
        uint repayAmount,
        CTokenInterface cTokenCollateral
    ) internal {
        /* Fail if liquidate not allowed */
        uint allowed = comptroller.liquidateBorrowAllowed(
            address(this),
            address(cTokenCollateral),
            liquidator,
            borrower,
            repayAmount
        );
        if (allowed != 0) {
            revert LiquidateComptrollerRejection(allowed);
        }

        /* Verify market's block number equals current block number */
        if (accrualBlockNumber != getBlockNumber()) {
            revert LiquidateFreshnessCheck();
        }

        /* Verify cTokenCollateral market's block number equals current block number */
        if (cTokenCollateral.accrualBlockNumber() != getBlockNumber()) {
            revert LiquidateCollateralFreshnessCheck();
        }

        /* Fail if borrower = liquidator */
        if (borrower == liquidator) {
            revert LiquidateLiquidatorIsBorrower();
        }

        /* Fail if repayAmount = 0 */
        if (repayAmount == 0) {
            revert LiquidateCloseAmountIsZero();
        }

        /* Fail if repayAmount = -1 */
        if (repayAmount == type(uint).max) {
            revert LiquidateCloseAmountIsUintMax();
        }

        /* Fail if repayBorrow fails */
        uint actualRepayAmount = repayBorrowFresh(
            liquidator,
            borrower,
            repayAmount
        );

        /////////////////////////
        // EFFECTS & INTERACTIONS
        // (No safe failures beyond this point)

        /* We calculate the number of collateral tokens that will be seized */
        (uint amountSeizeError, uint seizeTokens) = comptroller
            .liquidateCalculateSeizeTokens(
                address(this),
                address(cTokenCollateral),
                actualRepayAmount
            );
        require(
            amountSeizeError == NO_ERROR,
            "LIQUIDATE_COMPTROLLER_CALCULATE_AMOUNT_SEIZE_FAILED"
        );

        /* Revert if borrower collateral token balance < seizeTokens */
        require(
            cTokenCollateral.balanceOf(borrower) >= seizeTokens,
            "LIQUIDATE_SEIZE_TOO_MUCH"
        );

        // If this is also the collateral, run seizeInternal to avoid re-entrancy, otherwise make an external call
        if (address(cTokenCollateral) == address(this)) {
            seizeInternal(address(this), liquidator, borrower, seizeTokens);
        } else {
            require(
                cTokenCollateral.seize(liquidator, borrower, seizeTokens) ==
                    NO_ERROR,
                "token seizure failed"
            );
        }

        /* We emit a LiquidateBorrow event */
        emit LiquidateBorrow(
            liquidator,
            borrower,
            actualRepayAmount,
            address(cTokenCollateral),
            seizeTokens
        );
    }

    /**
     * @notice Transfers collateral tokens (this market) to the liquidator.
     * @dev Will fail unless called by another cToken during the process of liquidation.
     *  Its absolutely critical to use msg.sender as the borrowed cToken and not a parameter.
     * @param liquidator The account receiving seized collateral
     * @param borrower The account having collateral seized
     * @param seizeTokens The number of cTokens to seize
     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
     */
    function seize(
        address liquidator,
        address borrower,
        uint seizeTokens
    ) external override nonReentrant returns (uint) {
        seizeInternal(msg.sender, liquidator, borrower, seizeTokens);

        return NO_ERROR;
    }

    /**
     * @notice Transfers collateral tokens (this market) to the liquidator.
     * @dev Called only during an in-kind liquidation, or by liquidateBorrow during the liquidation of another CToken.
     *  Its absolutely critical to use msg.sender as the seizer cToken and not a parameter.
     * @param seizerToken The contract seizing the collateral (i.e. borrowed cToken)
     * @param liquidator The account receiving seized collateral
     * @param borrower The account having collateral seized
     * @param seizeTokens The number of cTokens to seize
     */
    function seizeInternal(
        address seizerToken,
        address liquidator,
        address borrower,
        uint seizeTokens
    ) internal {
        /* Fail if seize not allowed */
        uint allowed = comptroller.seizeAllowed(
            address(this),
            seizerToken,
            liquidator,
            borrower,
            seizeTokens
        );
        if (allowed != 0) {
            revert LiquidateSeizeComptrollerRejection(allowed);
        }

        /* Fail if borrower = liquidator */
        if (borrower == liquidator) {
            revert LiquidateSeizeLiquidatorIsBorrower();
        }

        /*
         * We calculate the new borrower and liquidator token balances, failing on underflow/overflow:
         *  borrowerTokensNew = accountTokens[borrower] - seizeTokens
         *  liquidatorTokensNew = accountTokens[liquidator] + seizeTokens
         */
        uint protocolSeizeTokens = mul_(
            seizeTokens,
            Exp({mantissa: protocolSeizeShareMantissa})
        );
        uint liquidatorSeizeTokens = seizeTokens - protocolSeizeTokens;
        Exp memory exchangeRate = Exp({mantissa: exchangeRateStoredInternal()});
        uint protocolSeizeAmount = mul_ScalarTruncate(
            exchangeRate,
            protocolSeizeTokens
        );
        uint totalReservesNew = totalReserves + protocolSeizeAmount;

        /////////////////////////
        // EFFECTS & INTERACTIONS
        // (No safe failures beyond this point)

        /* We write the calculated values into storage */
        totalReserves = totalReservesNew;
        totalSupply = totalSupply - protocolSeizeTokens;
        accountTokens[borrower] = accountTokens[borrower] - seizeTokens;
        accountTokens[liquidator] =
            accountTokens[liquidator] +
            liquidatorSeizeTokens;

        /* Emit a Transfer event */
        emit Transfer(borrower, liquidator, liquidatorSeizeTokens);
        emit Transfer(borrower, address(this), protocolSeizeTokens);
        emit ReservesAdded(
            address(this),
            protocolSeizeAmount,
            totalReservesNew
        );
    }

    /*** Admin Functions ***/

    /**
     * @notice Begins transfer of admin rights. The newPendingAdmin must call `_acceptAdmin` to finalize the transfer.
     * @dev Admin function to begin change of admin. The newPendingAdmin must call `_acceptAdmin` to finalize the transfer.
     * @param newPendingAdmin New pending admin.
     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
     */
    function _setPendingAdmin(
        address payable newPendingAdmin
    ) external override returns (uint) {
        // Check caller = admin
        if (msg.sender != admin) {
            revert SetPendingAdminOwnerCheck();
        }

        // Save current value, if any, for inclusion in log
        address oldPendingAdmin = pendingAdmin;

        // Store pendingAdmin with value newPendingAdmin
        pendingAdmin = newPendingAdmin;

        // Emit NewPendingAdmin(oldPendingAdmin, newPendingAdmin)
        emit NewPendingAdmin(oldPendingAdmin, newPendingAdmin);

        return NO_ERROR;
    }

    /**
     * @notice Accepts transfer of admin rights. msg.sender must be pendingAdmin
     * @dev Admin function for pending admin to accept role and update admin
     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
     */
    function _acceptAdmin() external override returns (uint) {
        // Check caller is pendingAdmin and pendingAdmin ≠ address(0)
        if (msg.sender != pendingAdmin || msg.sender == address(0)) {
            revert AcceptAdminPendingAdminCheck();
        }

        // Save current values for inclusion in log
        address oldAdmin = admin;
        address oldPendingAdmin = pendingAdmin;

        // Store admin with value pendingAdmin
        admin = pendingAdmin;

        // Clear the pending value
        pendingAdmin = payable(address(0));

        emit NewAdmin(oldAdmin, admin);
        emit NewPendingAdmin(oldPendingAdmin, pendingAdmin);

        return NO_ERROR;
    }

    /**
     * @notice Sets a new comptroller for the market
     * @dev Admin function to set a new comptroller
     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
     */
    function _setComptroller(
        ComptrollerInterface newComptroller
    ) public override returns (uint) {
        // Check caller is admin
        if (msg.sender != admin) {
            revert SetComptrollerOwnerCheck();
        }

        ComptrollerInterface oldComptroller = comptroller;
        // Ensure invoke comptroller.isComptroller() returns true
        require(newComptroller.isComptroller(), "marker method returned false");

        // Set market's comptroller to newComptroller
        comptroller = newComptroller;

        // Emit NewComptroller(oldComptroller, newComptroller)
        emit NewComptroller(oldComptroller, newComptroller);

        return NO_ERROR;
    }

    /**
     * @notice accrues interest and sets a new reserve factor for the protocol using _setReserveFactorFresh
     * @dev Admin function to accrue interest and set a new reserve factor
     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
     */
    function _setReserveFactor(
        uint newReserveFactorMantissa
    ) external override nonReentrant returns (uint) {
        accrueInterest();
        // _setReserveFactorFresh emits reserve-factor-specific logs on errors, so we don't need to.
        return _setReserveFactorFresh(newReserveFactorMantissa);
    }

    /**
     * @notice Sets a new reserve factor for the protocol (*requires fresh interest accrual)
     * @dev Admin function to set a new reserve factor
     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
     */
    function _setReserveFactorFresh(
        uint newReserveFactorMantissa
    ) internal returns (uint) {
        // Check caller is admin
        if (msg.sender != admin) {
            revert SetReserveFactorAdminCheck();
        }

        // Verify market's block number equals current block number
        if (accrualBlockNumber != getBlockNumber()) {
            revert SetReserveFactorFreshCheck();
        }

        // Check newReserveFactor ≤ maxReserveFactor
        if (newReserveFactorMantissa > reserveFactorMaxMantissa) {
            revert SetReserveFactorBoundsCheck();
        }

        uint oldReserveFactorMantissa = reserveFactorMantissa;
        reserveFactorMantissa = newReserveFactorMantissa;

        emit NewReserveFactor(
            oldReserveFactorMantissa,
            newReserveFactorMantissa
        );

        return NO_ERROR;
    }

    /**
     * @notice Accrues interest and reduces reserves by transferring from msg.sender
     * @param addAmount Amount of addition to reserves
     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
     */
    function _addReservesInternal(
        uint addAmount
    ) internal nonReentrant returns (uint) {
        accrueInterest();

        // _addReservesFresh emits reserve-addition-specific logs on errors, so we don't need to.
        _addReservesFresh(addAmount);
        return NO_ERROR;
    }

    /**
     * @notice Add reserves by transferring from caller
     * @dev Requires fresh interest accrual
     * @param addAmount Amount of addition to reserves
     * @return (uint, uint) An error code (0=success, otherwise a failure (see ErrorReporter.sol for details)) and the actual amount added, net token fees
     */
    function _addReservesFresh(uint addAmount) internal returns (uint, uint) {
        // totalReserves + actualAddAmount
        uint totalReservesNew;
        uint actualAddAmount;

        // We fail gracefully unless market's block number equals current block number
        if (accrualBlockNumber != getBlockNumber()) {
            revert AddReservesFactorFreshCheck(actualAddAmount);
        }

        /////////////////////////
        // EFFECTS & INTERACTIONS
        // (No safe failures beyond this point)

        /*
         * We call doTransferIn for the caller and the addAmount
         *  Note: The cToken must handle variations between ERC-20 and ETH underlying.
         *  On success, the cToken holds an additional addAmount of cash.
         *  doTransferIn reverts if anything goes wrong, since we can't be sure if side effects occurred.
         *  it returns the amount actually transferred, in case of a fee.
         */

        actualAddAmount = doTransferIn(msg.sender, addAmount);

        totalReservesNew = totalReserves + actualAddAmount;

        // Store reserves[n+1] = reserves[n] + actualAddAmount
        totalReserves = totalReservesNew;

        /* Emit NewReserves(admin, actualAddAmount, reserves[n+1]) */
        emit ReservesAdded(msg.sender, actualAddAmount, totalReservesNew);

        /* Return (NO_ERROR, actualAddAmount) */
        return (NO_ERROR, actualAddAmount);
    }

    /**
     * @notice Accrues interest and reduces reserves by transferring to admin
     * @param reduceAmount Amount of reduction to reserves
     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
     */
    function _reduceReserves(
        uint reduceAmount
    ) external override nonReentrant returns (uint) {
        accrueInterest();
        // _reduceReservesFresh emits reserve-reduction-specific logs on errors, so we don't need to.
        return _reduceReservesFresh(reduceAmount);
    }

    /**
     * @notice Reduces reserves by transferring to admin
     * @dev Requires fresh interest accrual
     * @param reduceAmount Amount of reduction to reserves
     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
     */
    function _reduceReservesFresh(uint reduceAmount) internal returns (uint) {
        // totalReserves - reduceAmount
        uint totalReservesNew;

        // Check caller is admin
        if (msg.sender != admin) {
            revert ReduceReservesAdminCheck();
        }

        // We fail gracefully unless market's block number equals current block number
        if (accrualBlockNumber != getBlockNumber()) {
            revert ReduceReservesFreshCheck();
        }

        // Fail gracefully if protocol has insufficient underlying cash
        if (getCashPrior() < reduceAmount) {
            revert ReduceReservesCashNotAvailable();
        }

        // Check reduceAmount ≤ reserves[n] (totalReserves)
        if (reduceAmount > totalReserves) {
            revert ReduceReservesCashValidation();
        }

        /////////////////////////
        // EFFECTS & INTERACTIONS
        // (No safe failures beyond this point)

        totalReservesNew = totalReserves - reduceAmount;

        // Store reserves[n+1] = reserves[n] - reduceAmount
        totalReserves = totalReservesNew;

        // doTransferOut reverts if anything goes wrong, since we can't be sure if side effects occurred.
        doTransferOut(admin, reduceAmount);

        emit ReservesReduced(admin, reduceAmount, totalReservesNew);

        return NO_ERROR;
    }

    /**
     * @notice accrues interest and updates the interest rate model using _setInterestRateModelFresh
     * @dev Admin function to accrue interest and update the interest rate model
     * @param newInterestRateModel the new interest rate model to use
     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
     */
    function _setInterestRateModel(
        InterestRateModel newInterestRateModel
    ) public override returns (uint) {
        accrueInterest();
        // _setInterestRateModelFresh emits interest-rate-model-update-specific logs on errors, so we don't need to.
        return _setInterestRateModelFresh(newInterestRateModel);
    }

    /**
     * @notice updates the interest rate model (*requires fresh interest accrual)
     * @dev Admin function to update the interest rate model
     * @param newInterestRateModel the new interest rate model to use
     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
     */
    function _setInterestRateModelFresh(
        InterestRateModel newInterestRateModel
    ) internal returns (uint) {
        // Used to store old model for use in the event that is emitted on success
        InterestRateModel oldInterestRateModel;

        // Check caller is admin
        if (msg.sender != admin) {
            revert SetInterestRateModelOwnerCheck();
        }

        // We fail gracefully unless market's block number equals current block number
        if (accrualBlockNumber != getBlockNumber()) {
            revert SetInterestRateModelFreshCheck();
        }

        // Track the market's current interest rate model
        oldInterestRateModel = interestRateModel;

        // Ensure invoke newInterestRateModel.isInterestRateModel() returns true
        require(
            newInterestRateModel.isInterestRateModel(),
            "marker method returned false"
        );

        // Set the interest rate model to newInterestRateModel
        interestRateModel = newInterestRateModel;

        // Emit NewMarketInterestRateModel(oldInterestRateModel, newInterestRateModel)
        emit NewMarketInterestRateModel(
            oldInterestRateModel,
            newInterestRateModel
        );

        return NO_ERROR;
    }

    /*** Safe Token ***/

    /**
     * @notice Gets balance of this contract in terms of the underlying
     * @dev This excludes the value of the current message, if any
     * @return The quantity of underlying owned by this contract
     */
    function getCashPrior() internal view virtual returns (uint);

    /**
     * @dev Performs a transfer in, reverting upon failure. Returns the amount actually transferred to the protocol, in case of a fee.
     *  This may revert due to insufficient balance or insufficient allowance.
     */
    function doTransferIn(
        address from,
        uint amount
    ) internal virtual returns (uint);

    /**
     * @dev Performs a transfer out, ideally returning an explanatory error code upon failure rather than reverting.
     *  If caller has not called checked protocol's balance, may revert due to insufficient cash held in the contract.
     *  If caller has checked protocol's balance, and verified it is >= amount, this should not revert in normal conditions.
     */
    function doTransferOut(address payable to, uint amount) internal virtual;

    /*** Reentrancy Guard ***/

    /**
     * @dev Prevents a contract from calling itself, directly or indirectly.
     */
    modifier nonReentrant() {
        require(_notEntered, "re-entered");
        _notEntered = false;
        _;
        _notEntered = true; // get a gas-refund post-Istanbul
    }
}

// File: contracts/CTokenInterfaces.sol



// SPDX-License-Identifier: BSD-3-Clause
pragma solidity ^0.8.10;

import "./ComptrollerInterface.sol";
import "./InterestRateModel.sol";
import "./EIP20NonStandardInterface.sol";
import "./ErrorReporter.sol";
import "./tbills/RiverKYCStorage.sol";

contract CTokenStorage {
    /**
     * @dev Guard variable for re-entrancy checks
     */
    bool internal _notEntered;

    /**
     * @notice EIP-20 token name for this token
     */
    string public name;

    /**
     * @notice EIP-20 token symbol for this token
     */
    string public symbol;

    /**
     * @notice EIP-20 token decimals for this token
     */
    uint8 public decimals;

    // Maximum borrow rate that can ever be applied (.0005% / block)
    uint internal constant borrowRateMaxMantissa = 0.0005e16;

    // Maximum fraction of interest that can be set aside for reserves
    uint internal constant reserveFactorMaxMantissa = 1e18;

    /**
     * @notice Administrator for this contract
     */
    address payable public admin;

    /**
     * @notice Pending administrator for this contract
     */
    address payable public pendingAdmin;

    /**
     * @notice Contract which oversees inter-cToken operations
     */
    ComptrollerInterface public comptroller;

    /**
     * @notice Model which tells what the current interest rate should be
     */
    InterestRateModel public interestRateModel;

    // Initial exchange rate used when minting the first CTokens (used when totalSupply = 0)
    uint internal initialExchangeRateMantissa;

    /**
     * @notice Fraction of interest currently set aside for reserves
     */
    uint public reserveFactorMantissa;

    /**
     * @notice Block number that interest was last accrued at
     */
    uint public accrualBlockNumber;

    /**
     * @notice Accumulator of the total earned interest rate since the opening of the market
     */
    uint public borrowIndex;

    /**
     * @notice Total amount of outstanding borrows of the underlying in this market
     */
    uint public totalBorrows;

    /**
     * @notice Total amount of reserves of the underlying held in this market
     */
    uint public totalReserves;

    /**
     * @notice Total number of tokens in circulation
     */
    uint public totalSupply;

    // Official record of token balances for each account
    mapping(address => uint) internal accountTokens;

    // Approved token transfer amounts on behalf of others
    mapping(address => mapping(address => uint)) internal transferAllowances;

    /**
     * @notice Container for borrow balance information
     * @member principal Total balance (with accrued interest), after applying the most recent balance-changing action
     * @member interestIndex Global borrowIndex as of the most recent balance-changing action
     */
    struct BorrowSnapshot {
        uint principal;
        uint interestIndex;
    }

    // Mapping of account addresses to outstanding borrow balances
    mapping(address => BorrowSnapshot) internal accountBorrows;

    /**
     * @notice Share of seized collateral that is added to reserves
     */
    // uint public constant protocolSeizeShareMantissa = 2.8e16; //2.8%
    // changed by rivers
    uint public constant protocolSeizeShareMantissa = 0;
}

abstract contract CTokenInterface is CTokenStorage, RiverKYCStorage {
    /**
     * @notice Indicator that this is a CToken contract (for inspection)
     */
    bool public constant isCToken = true;

    /*** Market Events ***/

    /**
     * @notice Event emitted when interest is accrued
     */
    event AccrueInterest(
        uint cashPrior,
        uint interestAccumulated,
        uint borrowIndex,
        uint totalBorrows
    );

    /**
     * @notice Event emitted when tokens are minted
     */
    event Mint(address minter, uint mintAmount, uint mintTokens);

    /**
     * @notice Event emitted when tokens are redeemed
     */
    event Redeem(address redeemer, uint redeemAmount, uint redeemTokens);

    /**
     * @notice Event emitted when underlying is borrowed
     */
    event Borrow(
        address borrower,
        uint borrowAmount,
        uint accountBorrows,
        uint totalBorrows
    );

    /**
     * @notice Event emitted when a borrow is repaid
     */
    event RepayBorrow(
        address payer,
        address borrower,
        uint repayAmount,
        uint accountBorrows,
        uint totalBorrows
    );

    /**
     * @notice Event emitted when a borrow is liquidated
     */
    event LiquidateBorrow(
        address liquidator,
        address borrower,
        uint repayAmount,
        address cTokenCollateral,
        uint seizeTokens
    );

    /*** Admin Events ***/

    /**
     * @notice Event emitted when pendingAdmin is changed
     */
    event NewPendingAdmin(address oldPendingAdmin, address newPendingAdmin);

    /**
     * @notice Event emitted when pendingAdmin is accepted, which means admin is updated
     */
    event NewAdmin(address oldAdmin, address newAdmin);

    /**
     * @notice Event emitted when comptroller is changed
     */
    event NewComptroller(
        ComptrollerInterface oldComptroller,
        ComptrollerInterface newComptroller
    );

    /**
     * @notice Event emitted when interestRateModel is changed
     */
    event NewMarketInterestRateModel(
        InterestRateModel oldInterestRateModel,
        InterestRateModel newInterestRateModel
    );

    /**
     * @notice Event emitted when the reserve factor is changed
     */
    event NewReserveFactor(
        uint oldReserveFactorMantissa,
        uint newReserveFactorMantissa
    );

    /**
     * @notice Event emitted when the reserves are added
     */
    event ReservesAdded(
        address benefactor,
        uint addAmount,
        uint newTotalReserves
    );

    /**
     * @notice Event emitted when the reserves are reduced
     */
    event ReservesReduced(
        address admin,
        uint reduceAmount,
        uint newTotalReserves
    );

    /**
     * @notice EIP20 Transfer event
     */
    event Transfer(address indexed from, address indexed to, uint amount);

    /**
     * @notice EIP20 Approval event
     */
    event Approval(address indexed owner, address indexed spender, uint amount);

    /*** User Interface ***/

    function transfer(address dst, uint amount) external virtual returns (bool);

    function transferFrom(
        address src,
        address dst,
        uint amount
    ) external virtual returns (bool);

    function approve(
        address spender,
        uint amount
    ) external virtual returns (bool);

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

    function balanceOf(address owner) external view virtual returns (uint);

    function balanceOfUnderlying(address owner) external virtual returns (uint);

    function getAccountSnapshot(
        address account
    ) external view virtual returns (uint, uint, uint, uint);

    function borrowRatePerBlock() external view virtual returns (uint);

    function supplyRatePerBlock() external view virtual returns (uint);

    function totalBorrowsCurrent() external virtual returns (uint);

    function borrowBalanceCurrent(
        address account
    ) external virtual returns (uint);

    function borrowBalanceStored(
        address account
    ) external view virtual returns (uint);

    function exchangeRateCurrent() external virtual returns (uint);

    function exchangeRateStored() external view virtual returns (uint);

    function getCash() external view virtual returns (uint);

    function accrueInterest() external virtual returns (uint);

    function seize(
        address liquidator,
        address borrower,
        uint seizeTokens
    ) external virtual returns (uint);

    /*** Admin Functions ***/

    function _setPendingAdmin(
        address payable newPendingAdmin
    ) external virtual returns (uint);

    function _acceptAdmin() external virtual returns (uint);

    function _setComptroller(
        ComptrollerInterface newComptroller
    ) external virtual returns (uint);

    function _setReserveFactor(
        uint newReserveFactorMantissa
    ) external virtual returns (uint);

    function _reduceReserves(uint reduceAmount) external virtual returns (uint);

    function _setInterestRateModel(
        InterestRateModel newInterestRateModel
    ) external virtual returns (uint);
}

contract CErc20Storage {
    /**
     * @notice Underlying asset for this CToken
     */
    address public underlying;
}

abstract contract CErc20Interface is CErc20Storage {
    /*** User Interface ***/

    function mint(uint mintAmount) external virtual returns (uint);

    function redeem(uint redeemTokens) external virtual returns (uint);

    function redeemUnderlying(
        uint redeemAmount
    ) external virtual returns (uint);

    function borrow(uint borrowAmount) external virtual returns (uint);

    function repayBorrow(uint repayAmount) external virtual returns (uint);

    function repayBorrowBehalf(
        address borrower,
        uint repayAmount
    ) external virtual returns (uint);

    function liquidateBorrow(
        address borrower,
        uint repayAmount,
        CTokenInterface cTokenCollateral
    ) external virtual returns (uint);

    function sweepToken(EIP20NonStandardInterface token) external virtual;

    /*** Admin Functions ***/

    function _addReserves(uint addAmount) external virtual returns (uint);
}

contract CDelegationStorage {
    /**
     * @notice Implementation address for this contract
     */
    address public implementation;
}

abstract contract CDelegatorInterface is CDelegationStorage {
    /**
     * @notice Emitted when implementation is changed
     */
    event NewImplementation(
        address oldImplementation,
        address newImplementation
    );

    /**
     * @notice Called by the admin to update the implementation of the delegator
     * @param implementation_ The address of the new implementation for delegation
     * @param allowResign Flag to indicate whether to call _resignImplementation on the old implementation
     * @param becomeImplementationData The encoded bytes data to be passed to _becomeImplementation
     */
    function _setImplementation(
        address implementation_,
        bool allowResign,
        bytes memory becomeImplementationData
    ) external virtual;
}

abstract contract CDelegateInterface is CDelegationStorage {
    /**
     * @notice Called by the delegator on a delegate to initialize it for duty
     * @dev Should revert if any issues arise which make it unfit for delegation
     * @param data The encoded bytes data for any initialization
     */
    function _becomeImplementation(bytes memory data) external virtual;

    /**
     * @notice Called by the delegator on a delegate to forfeit its responsibility
     */
    function _resignImplementation() external virtual;
}

// File: contracts/EIP20Interface.sol



// SPDX-License-Identifier: BSD-3-Clause
pragma solidity ^0.8.10;

/**
 * @title ERC 20 Token Standard Interface
 *  https://eips.ethereum.org/EIPS/eip-20
 */
interface EIP20Interface {
    function name() external view returns (string memory);

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

    function decimals() external view returns (uint8);

    /**
     * @notice Get the total number of tokens in circulation
     * @return The supply of tokens
     */
    function totalSupply() external view returns (uint256);

    /**
     * @notice Gets the balance of the specified address
     * @param owner The address from which the balance will be retrieved
     * @return balance The balance
     */
    function balanceOf(address owner) external view returns (uint256 balance);

    /**
     * @notice Transfer `amount` tokens from `msg.sender` to `dst`
     * @param dst The address of the destination account
     * @param amount The number of tokens to transfer
     * @return success Whether or not the transfer succeeded
     */
    function transfer(
        address dst,
        uint256 amount
    ) external returns (bool success);

    /**
     * @notice Transfer `amount` tokens from `src` to `dst`
     * @param src The address of the source account
     * @param dst The address of the destination account
     * @param amount The number of tokens to transfer
     * @return success Whether or not the transfer succeeded
     */
    function transferFrom(
        address src,
        address dst,
        uint256 amount
    ) external returns (bool success);

    /**
     * @notice Approve `spender` to transfer up to `amount` from `src`
     * @dev This will overwrite the approval amount for `spender`
     *  and is subject to issues noted [here](https://eips.ethereum.org/EIPS/eip-20#approve)
     * @param spender The address of the account which may transfer tokens
     * @param amount The number of tokens that are approved (-1 means infinite)
     * @return success Whether or not the approval succeeded
     */
    function approve(
        address spender,
        uint256 amount
    ) external returns (bool success);

    /**
     * @notice Get the current allowance from `owner` for `spender`
     * @param owner The address of the account which owns the tokens to be spent
     * @param spender The address of the account which may transfer tokens
     * @return remaining The number of tokens allowed to be spent (-1 means infinite)
     */
    function allowance(
        address owner,
        address spender
    ) external view returns (uint256 remaining);

    event Transfer(address indexed from, address indexed to, uint256 amount);
    event Approval(
        address indexed owner,
        address indexed spender,
        uint256 amount
    );
}

// File: contracts/EIP20NonStandardInterface.sol



// SPDX-License-Identifier: BSD-3-Clause
pragma solidity ^0.8.10;

/**
 * @title EIP20NonStandardInterface
 * @dev Version of ERC20 with no return values for `transfer` and `transferFrom`
 *  See https://medium.com/coinmonks/missing-return-value-bug-at-least-130-tokens-affected-d67bf08521ca
 */
interface EIP20NonStandardInterface {
    /**
     * @notice Get the total number of tokens in circulation
     * @return The supply of tokens
     */
    function totalSupply() external view returns (uint256);

    /**
     * @notice Gets the balance of the specified address
     * @param owner The address from which the balance will be retrieved
     * @return balance The balance
     */
    function balanceOf(address owner) external view returns (uint256 balance);

    ///
    /// !!!!!!!!!!!!!!
    /// !!! NOTICE !!! `transfer` does not return a value, in violation of the ERC-20 specification
    /// !!!!!!!!!!!!!!
    ///

    /**
     * @notice Transfer `amount` tokens from `msg.sender` to `dst`
     * @param dst The address of the destination account
     * @param amount The number of tokens to transfer
     */
    function transfer(address dst, uint256 amount) external;

    ///
    /// !!!!!!!!!!!!!!
    /// !!! NOTICE !!! `transferFrom` does not return a value, in violation of the ERC-20 specification
    /// !!!!!!!!!!!!!!
    ///

    /**
     * @notice Transfer `amount` tokens from `src` to `dst`
     * @param src The address of the source account
     * @param dst The address of the destination account
     * @param amount The number of tokens to transfer
     */
    function transferFrom(address src, address dst, uint256 amount) external;

    /**
     * @notice Approve `spender` to transfer up to `amount` from `src`
     * @dev This will overwrite the approval amount for `spender`
     *  and is subject to issues noted [here](https://eips.ethereum.org/EIPS/eip-20#approve)
     * @param spender The address of the account which may transfer tokens
     * @param amount The number of tokens that are approved
     * @return success Whether or not the approval succeeded
     */
    function approve(
        address spender,
        uint256 amount
    ) external returns (bool success);

    /**
     * @notice Get the current allowance from `owner` for `spender`
     * @param owner The address of the account which owns the tokens to be spent
     * @param spender The address of the account which may transfer tokens
     * @return remaining The number of tokens allowed to be spent
     */
    function allowance(
        address owner,
        address spender
    ) external view returns (uint256 remaining);

    event Transfer(address indexed from, address indexed to, uint256 amount);
    event Approval(
        address indexed owner,
        address indexed spender,
        uint256 amount
    );
}

// File: contracts/ErrorReporter.sol



// SPDX-License-Identifier: BSD-3-Clause
pragma solidity ^0.8.10;

contract ComptrollerErrorReporter {
    enum Error {
        NO_ERROR,
        UNAUTHORIZED,
        COMPTROLLER_MISMATCH,
        INSUFFICIENT_SHORTFALL,
        INSUFFICIENT_LIQUIDITY,
        INVALID_CLOSE_FACTOR,
        INVALID_COLLATERAL_FACTOR,
        INVALID_LIQUIDATION_INCENTIVE,
        MARKET_NOT_ENTERED, // no longer possible
        MARKET_NOT_LISTED,
        MARKET_ALREADY_LISTED,
        MATH_ERROR,
        NONZERO_BORROW_BALANCE,
        PRICE_ERROR,
        REJECTION,
        SNAPSHOT_ERROR,
        TOO_MANY_ASSETS,
        TOO_MUCH_REPAY
    }

    enum FailureInfo {
        ACCEPT_ADMIN_PENDING_ADMIN_CHECK,
        ACCEPT_PENDING_IMPLEMENTATION_ADDRESS_CHECK,
        EXIT_MARKET_BALANCE_OWED,
        EXIT_MARKET_REJECTION,
        SET_CLOSE_FACTOR_OWNER_CHECK,
        SET_CLOSE_FACTOR_VALIDATION,
        SET_COLLATERAL_FACTOR_OWNER_CHECK,
        SET_COLLATERAL_FACTOR_NO_EXISTS,
        SET_COLLATERAL_FACTOR_VALIDATION,
        SET_COLLATERAL_FACTOR_WITHOUT_PRICE,
        SET_IMPLEMENTATION_OWNER_CHECK,
        SET_LIQUIDATION_INCENTIVE_OWNER_CHECK,
        SET_LIQUIDATION_INCENTIVE_VALIDATION,
        SET_MAX_ASSETS_OWNER_CHECK,
        SET_PENDING_ADMIN_OWNER_CHECK,
        SET_PENDING_IMPLEMENTATION_OWNER_CHECK,
        SET_PRICE_ORACLE_OWNER_CHECK,
        SUPPORT_MARKET_EXISTS,
        SUPPORT_MARKET_OWNER_CHECK,
        SET_PAUSE_GUARDIAN_OWNER_CHECK
    }

    /**
     * @dev `error` corresponds to enum Error; `info` corresponds to enum FailureInfo, and `detail` is an arbitrary
     * contract-specific code that enables us to report opaque error codes from upgradeable contracts.
     **/
    event Failure(uint error, uint info, uint detail);

    /**
     * @dev use this when reporting a known error from the money market or a non-upgradeable collaborator
     */
    function fail(Error err, FailureInfo info) internal returns (uint) {
        emit Failure(uint(err), uint(info), 0);

        return uint(err);
    }

    /**
     * @dev use this when reporting an opaque error from an upgradeable collaborator contract
     */
    function failOpaque(
        Error err,
        FailureInfo info,
        uint opaqueError
    ) internal returns (uint) {
        emit Failure(uint(err), uint(info), opaqueError);

        return uint(err);
    }
}

contract TokenErrorReporter {
    uint public constant NO_ERROR = 0; // support legacy return codes

    error TransferComptrollerRejection(uint256 errorCode);
    error TransferNotAllowed();
    error TransferNotEnough();
    error TransferTooMuch();

    error MintComptrollerRejection(uint256 errorCode);
    error MintFreshnessCheck();

    error RedeemComptrollerRejection(uint256 errorCode);
    error RedeemFreshnessCheck();
    error RedeemTransferOutNotPossible();

    error BorrowComptrollerRejection(uint256 errorCode);
    error BorrowFreshnessCheck();
    error BorrowCashNotAvailable();

    error RepayBorrowComptrollerRejection(uint256 errorCode);
    error RepayBorrowFreshnessCheck();

    error LiquidateComptrollerRejection(uint256 errorCode);
    error LiquidateFreshnessCheck();
    error LiquidateCollateralFreshnessCheck();
    error LiquidateAccrueBorrowInterestFailed(uint256 errorCode);
    error LiquidateAccrueCollateralInterestFailed(uint256 errorCode);
    error LiquidateLiquidatorIsBorrower();
    error LiquidateCloseAmountIsZero();
    error LiquidateCloseAmountIsUintMax();
    error LiquidateRepayBorrowFreshFailed(uint256 errorCode);

    error LiquidateSeizeComptrollerRejection(uint256 errorCode);
    error LiquidateSeizeLiquidatorIsBorrower();

    error AcceptAdminPendingAdminCheck();

    error SetComptrollerOwnerCheck();
    error SetPendingAdminOwnerCheck();

    error SetReserveFactorAdminCheck();
    error SetReserveFactorFreshCheck();
    error SetReserveFactorBoundsCheck();

    error AddReservesFactorFreshCheck(uint256 actualAddAmount);

    error ReduceReservesAdminCheck();
    error ReduceReservesFreshCheck();
    error ReduceReservesCashNotAvailable();
    error ReduceReservesCashValidation();

    error SetInterestRateModelOwnerCheck();
    error SetInterestRateModelFreshCheck();
}

// File: contracts/ExponentialNoError.sol



// SPDX-License-Identifier: BSD-3-Clause
pragma solidity ^0.8.10;

/**
 * @title Exponential module for storing fixed-precision decimals
 * @author Compound
 * @notice Exp is a struct which stores decimals with a fixed precision of 18 decimal places.
 *         Thus, if we wanted to store the 5.1, mantissa would store 5.1e18. That is:
 *         `Exp({mantissa: 5100000000000000000})`.
 */
contract ExponentialNoError {
    uint constant expScale = 1e18;
    uint constant doubleScale = 1e36;
    uint constant halfExpScale = expScale / 2;
    uint constant mantissaOne = expScale;

    struct Exp {
        uint mantissa;
    }

    struct Double {
        uint mantissa;
    }

    /**
     * @dev Truncates the given exp to a whole number value.
     *      For example, truncate(Exp{mantissa: 15 * expScale}) = 15
     */
    function truncate(Exp memory exp) internal pure returns (uint) {
        // Note: We are not using careful math here as we're performing a division that cannot fail
        return exp.mantissa / expScale;
    }

    /**
     * @dev Multiply an Exp by a scalar, then truncate to return an unsigned integer.
     */
    function mul_ScalarTruncate(
        Exp memory a,
        uint scalar
    ) internal pure returns (uint) {
        Exp memory product = mul_(a, scalar);
        return truncate(product);
    }

    /**
     * @dev Multiply an Exp by a scalar, truncate, then add an to an unsigned integer, returning an unsigned integer.
     */
    function mul_ScalarTruncateAddUInt(
        Exp memory a,
        uint scalar,
        uint addend
    ) internal pure returns (uint) {
        Exp memory product = mul_(a, scalar);
        return add_(truncate(product), addend);
    }

    /**
     * @dev Checks if first Exp is less than second Exp.
     */
    function lessThanExp(
        Exp memory left,
        Exp memory right
    ) internal pure returns (bool) {
        return left.mantissa < right.mantissa;
    }

    /**
     * @dev Checks if left Exp <= right Exp.
     */
    function lessThanOrEqualExp(
        Exp memory left,
        Exp memory right
    ) internal pure returns (bool) {
        return left.mantissa <= right.mantissa;
    }

    /**
     * @dev Checks if left Exp > right Exp.
     */
    function greaterThanExp(
        Exp memory left,
        Exp memory right
    ) internal pure returns (bool) {
        return left.mantissa > right.mantissa;
    }

    /**
     * @dev returns true if Exp is exactly zero
     */
    function isZeroExp(Exp memory value) internal pure returns (bool) {
        return value.mantissa == 0;
    }

    function safe224(
        uint n,
        string memory errorMessage
    ) internal pure returns (uint224) {
        require(n < 2 ** 224, errorMessage);
        return uint224(n);
    }

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

    function add_(
        Exp memory a,
        Exp memory b
    ) internal pure returns (Exp memory) {
        return Exp({mantissa: add_(a.mantissa, b.mantissa)});
    }

    function add_(
        Double memory a,
        Double memory b
    ) internal pure returns (Double memory) {
        return Double({mantissa: add_(a.mantissa, b.mantissa)});
    }

    function add_(uint a, uint b) internal pure returns (uint) {
        return a + b;
    }

    function sub_(
        Exp memory a,
        Exp memory b
    ) internal pure returns (Exp memory) {
        return Exp({mantissa: sub_(a.mantissa, b.mantissa)});
    }

    function sub_(
        Double memory a,
        Double memory b
    ) internal pure returns (Double memory) {
        return Double({mantissa: sub_(a.mantissa, b.mantissa)});
    }

    function sub_(uint a, uint b) internal pure returns (uint) {
        return a - b;
    }

    function mul_(
        Exp memory a,
        Exp memory b
    ) internal pure returns (Exp memory) {
        return Exp({mantissa: mul_(a.mantissa, b.mantissa) / expScale});
    }

    function mul_(Exp memory a, uint b) internal pure returns (Exp memory) {
        return Exp({mantissa: mul_(a.mantissa, b)});
    }

    function mul_(uint a, Exp memory b) internal pure returns (uint) {
        return mul_(a, b.mantissa) / expScale;
    }

    function mul_(
        Double memory a,
        Double memory b
    ) internal pure returns (Double memory) {
        return Double({mantissa: mul_(a.mantissa, b.mantissa) / doubleScale});
    }

    function mul_(
        Double memory a,
        uint b
    ) internal pure returns (Double memory) {
        return Double({mantissa: mul_(a.mantissa, b)});
    }

    function mul_(uint a, Double memory b) internal pure returns (uint) {
        return mul_(a, b.mantissa) / doubleScale;
    }

    function mul_(uint a, uint b) internal pure returns (uint) {
        return a * b;
    }

    function div_(
        Exp memory a,
        Exp memory b
    ) internal pure returns (Exp memory) {
        return Exp({mantissa: div_(mul_(a.mantissa, expScale), b.mantissa)});
    }

    function div_(Exp memory a, uint b) internal pure returns (Exp memory) {
        return Exp({mantissa: div_(a.mantissa, b)});
    }

    function div_(uint a, Exp memory b) internal pure returns (uint) {
        return div_(mul_(a, expScale), b.mantissa);
    }

    function div_(
        Double memory a,
        Double memory b
    ) internal pure returns (Double memory) {
        return
            Double({mantissa: div_(mul_(a.mantissa, doubleScale), b.mantissa)});
    }

    function div_(
        Double memory a,
        uint b
    ) internal pure returns (Double memory) {
        return Double({mantissa: div_(a.mantissa, b)});
    }

    function div_(uint a, Double memory b) internal pure returns (uint) {
        return div_(mul_(a, doubleScale), b.mantissa);
    }

    function div_(uint a, uint b) internal pure returns (uint) {
        return a / b;
    }

    function fraction(uint a, uint b) internal pure returns (Double memory) {
        return Double({mantissa: div_(mul_(a, doubleScale), b)});
    }
}

// File: contracts/Governance/River.sol



// SPDX-License-Identifier: BSD-3-Clause
pragma solidity ^0.8.10;

contract River {
    /// @notice EIP-20 token name for this token
    string public constant name = "River";

    /// @notice EIP-20 token symbol for this token
    string public constant symbol = "RIV";

    /// @notice EIP-20 token decimals for this token
    uint8 public constant decimals = 18;

    /// @notice Total number of tokens in circulation
    uint public constant totalSupply = 10000000e18; // 10 million river

    /// @notice Allowance amounts on behalf of others
    mapping(address => mapping(address => uint96)) internal allowances;

    /// @notice Official record of token balances for each account
    mapping(address => uint96) internal balances;

    /// @notice A record of each accounts delegate
    mapping(address => address) public delegates;

    /// @notice A checkpoint for marking number of votes from a given block
    struct Checkpoint {
        uint32 fromBlock;
        uint96 votes;
    }

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

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

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

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

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

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

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

    /// @notice The standard EIP-20 transfer event
    event Transfer(address indexed from, address indexed to, uint256 amount);

    /// @notice The standard EIP-20 approval event
    event Approval(
        address indexed owner,
        address indexed spender,
        uint256 amount
    );

    /**
     * @notice Construct a new river token
     * @param account The initial account to grant all the tokens
     */
    constructor(address account) public {
        balances[account] = uint96(totalSupply);
        emit Transfer(address(0), account, totalSupply);
    }

    /**
     * @notice Get the number of tokens `spender` is approved to spend on behalf of `account`
     * @param account The address of the account holding the funds
     * @param spender The address of the account spending the funds
     * @return The number of tokens approved
     */
    function allowance(
        address account,
        address spender
    ) external view returns (uint) {
        return allowances[account][spender];
    }

    /**
     * @notice Approve `spender` to transfer up to `amount` from `src`
     * @dev This will overwrite the approval amount for `spender`
     *  and is subject to issues noted [here](https://eips.ethereum.org/EIPS/eip-20#approve)
     * @param spender The address of the account which may transfer tokens
     * @param rawAmount The number of tokens that are approved (2^256-1 means infinite)
     * @return Whether or not the approval succeeded
     */
    function approve(address spender, uint rawAmount) external returns (bool) {
        uint96 amount;
        if (rawAmount == type(uint).max) {
            amount = type(uint96).max;
        } else {
            amount = safe96(
                rawAmount,
                "River::approve: amount exceeds 96 bits"
            );
        }

        allowances[msg.sender][spender] = amount;

        emit Approval(msg.sender, spender, amount);
        return true;
    }

    /**
     * @notice Get the number of tokens held by the `account`
     * @param account The address of the account to get the balance of
     * @return The number of tokens held
     */
    function balanceOf(address account) external view returns (uint) {
        return balances[account];
    }

    /**
     * @notice Transfer `amount` tokens from `msg.sender` to `dst`
     * @param dst The address of the destination account
     * @param rawAmount The number of tokens to transfer
     * @return Whether or not the transfer succeeded
     */
    function transfer(address dst, uint rawAmount) external returns (bool) {
        uint96 amount = safe96(
            rawAmount,
            "River::transfer: amount exceeds 96 bits"
        );
        _transferTokens(msg.sender, dst, amount);
        return true;
    }

    /**
     * @notice Transfer `amount` tokens from `src` to `dst`
     * @param src The address of the source account
     * @param dst The address of the destination account
     * @param rawAmount The number of tokens to transfer
     * @return Whether or not the transfer succeeded
     */
    function transferFrom(
        address src,
        address dst,
        uint rawAmount
    ) external returns (bool) {
        address spender = msg.sender;
        uint96 spenderAllowance = allowances[src][spender];
        uint96 amount = safe96(
            rawAmount,
            "River::approve: amount exceeds 96 bits"
        );

        if (spender != src && spenderAllowance != type(uint96).max) {
            uint96 newAllowance = sub96(
                spenderAllowance,
                amount,
                "River::transferFrom: transfer amount exceeds spender allowance"
            );
            allowances[src][spender] = newAllowance;

            emit Approval(src, spender, newAllowance);
        }

        _transferTokens(src, dst, amount);
        return true;
    }

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

    /**
     * @notice Delegates votes from signatory to `delegatee`
     * @param delegatee The address to delegate votes to
     * @param nonce The contract state required to match the signature
     * @param expiry The time at which to expire the signature
     * @param v The recovery byte of the signature
     * @param r Half of the ECDSA signature pair
     * @param s Half of the ECDSA signature pair
     */
    function delegateBySig(
        address delegatee,
        uint nonce,
        uint expiry,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) public {
        bytes32 domainSeparator = keccak256(
            abi.encode(
                DOMAIN_TYPEHASH,
                keccak256(bytes(name)),
                getChainId(),
                address(this)
            )
        );
        bytes32 structHash = keccak256(
            abi.encode(DELEGATION_TYPEHASH, delegatee, nonce, expiry)
        );
        bytes32 digest = keccak256(
            abi.encodePacked("\x19\x01", domainSeparator, structHash)
        );
        address signatory = ecrecover(digest, v, r, s);
        require(
            signatory != address(0),
            "River::delegateBySig: invalid signature"
        );
        require(
            nonce == nonces[signatory]++,
            "River::delegateBySig: invalid nonce"
        );
        require(
            block.timestamp <= expiry,
            "River::delegateBySig: signature expired"
        );
        return _delegate(signatory, delegatee);
    }

    /**
     * @notice Gets the current votes balance for `account`
     * @param account The address to get votes balance
     * @return The number of current votes for `account`
     */
    function getCurrentVotes(address account) external view returns (uint96) {
        uint32 nCheckpoints = numCheckpoints[account];
        return
            nCheckpoints > 0 ? checkpoints[account][nCheckpoints - 1].votes : 0;
    }

    /**
     * @notice Determine the prior number of votes for an account as of a block number
     * @dev Block number must be a finalized block or else this function will revert to prevent misinformation.
     * @param account The address of the account to check
     * @param blockNumber The block number to get the vote balance at
     * @return The number of votes the account had as of the given block
     */
    function getPriorVotes(
        address account,
        uint blockNumber
    ) public view returns (uint96) {
        require(
            blockNumber < block.number,
            "River::getPriorVotes: not yet determined"
        );

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

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

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

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

    function _delegate(address delegator, address delegatee) internal {
        address currentDelegate = delegates[delegator];
        uint96 delegatorBalance = balances[delegator];
        delegates[delegator] = delegatee;

        emit DelegateChanged(delegator, currentDelegate, delegatee);

        _moveDelegates(currentDelegate, delegatee, delegatorBalance);
    }

    function _transferTokens(address src, address dst, uint96 amount) internal {
        require(
            src != address(0),
            "River::_transferTokens: cannot transfer from the zero address"
        );
        require(
            dst != address(0),
            "River::_transferTokens: cannot transfer to the zero address"
        );

        balances[src] = sub96(
            balances[src],
            amount,
            "River::_transferTokens: transfer amount exceeds balance"
        );
        balances[dst] = add96(
            balances[dst],
            amount,
            "River::_transferTokens: transfer amount overflows"
        );
        emit Transfer(src, dst, amount);

        _moveDelegates(delegates[src], delegates[dst], amount);
    }

    function _moveDelegates(
        address srcRep,
        address dstRep,
        uint96 amount
    ) internal {
        if (srcRep != dstRep && amount > 0) {
            if (srcRep != address(0)) {
                uint32 srcRepNum = numCheckpoints[srcRep];
                uint96 srcRepOld = srcRepNum > 0
                    ? checkpoints[srcRep][srcRepNum - 1].votes
                    : 0;
                uint96 srcRepNew = sub96(
                    srcRepOld,
                    amount,
                    "River::_moveVotes: vote amount underflows"
                );
                _writeCheckpoint(srcRep, srcRepNum, srcRepOld, srcRepNew);
            }

            if (dstRep != address(0)) {
                uint32 dstRepNum = numCheckpoints[dstRep];
                uint96 dstRepOld = dstRepNum > 0
                    ? checkpoints[dstRep][dstRepNum - 1].votes
                    : 0;
                uint96 dstRepNew = add96(
                    dstRepOld,
                    amount,
                    "River::_moveVotes: vote amount overflows"
                );
                _writeCheckpoint(dstRep, dstRepNum, dstRepOld, dstRepNew);
            }
        }
    }

    function _writeCheckpoint(
        address delegatee,
        uint32 nCheckpoints,
        uint96 oldVotes,
        uint96 newVotes
    ) internal {
        uint32 blockNumber = safe32(
            block.number,
            "River::_writeCheckpoint: block number exceeds 32 bits"
        );

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

        emit DelegateVotesChanged(delegatee, oldVotes, newVotes);
    }

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

    function safe96(
        uint n,
        string memory errorMessage
    ) internal pure returns (uint96) {
        require(n < 2 ** 96, errorMessage);
        return uint96(n);
    }

    function add96(
        uint96 a,
        uint96 b,
        string memory errorMessage
    ) internal pure returns (uint96) {
        uint96 c = a + b;
        require(c >= a, errorMessage);
        return c;
    }

    function sub96(
        uint96 a,
        uint96 b,
        string memory errorMessage
    ) internal pure returns (uint96) {
        require(b <= a, errorMessage);
        return a - b;
    }

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

// File: contracts/InterestRateModel.sol



// SPDX-License-Identifier: BSD-3-Clause
pragma solidity ^0.8.10;

/**
 * @title Compound's InterestRateModel Interface
 * @author Compound
 */
abstract contract InterestRateModel {
    /// @notice Indicator that this is an InterestRateModel contract (for inspection)
    bool public constant isInterestRateModel = true;

    /**
     * @notice Calculates the current borrow interest rate per block
     * @param cash The total amount of cash the market has
     * @param borrows The total amount of borrows the market has outstanding
     * @param reserves The total amount of reserves the market has
     * @return The borrow rate per block (as a percentage, and scaled by 1e18)
     */
    function getBorrowRate(
        uint cash,
        uint borrows,
        uint reserves
    ) external view virtual returns (uint);

    /**
     * @notice Calculates the current supply interest rate per block
     * @param cash The total amount of cash the market has
     * @param borrows The total amount of borrows the market has outstanding
     * @param reserves The total amount of reserves the market has
     * @param reserveFactorMantissa The current reserve factor the market has
     * @return The supply rate per block (as a percentage, and scaled by 1e18)
     */
    function getSupplyRate(
        uint cash,
        uint borrows,
        uint reserves,
        uint reserveFactorMantissa
    ) external view virtual returns (uint);
}

// File: contracts/PriceOracle.sol



// SPDX-License-Identifier: BSD-3-Clause
pragma solidity ^0.8.10;

import "./CToken.sol";

abstract contract PriceOracle {
    /// @notice Indicator that this is a PriceOracle contract (for inspection)
    bool public constant isPriceOracle = true;

    /**
     * @notice Get the underlying price of a cToken asset
     * @param cToken The cToken to get the underlying price of
     * @return The underlying asset price mantissa (scaled by 1e18).
     *  Zero means the price is unavailable.
     */
    function getUnderlyingPrice(
        CToken cToken
    ) external view virtual returns (uint);
}

// File: contracts/tbills/IKycManager.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.4;

/**
 * @title IKycManager
 * @author River
 * @notice The interface for River's KYC Manager contract
 */
interface IKycManager {
    enum KycType {
        NON_KYC,
        US_KYC,
        GENERAL_KYC
    }

    struct User {
        KycType kycType;
        bool isBanned;
    }

    function onlyNotBanned(address investor) external view;

    function onlyKyc(address investor) external view;

    function isBanned(address investor) external view returns (bool);

    function isKyc(address investor) external view returns (bool);

    function isUSKyc(address investor) external view returns (bool);

    function isNonUSKyc(address investor) external view returns (bool);

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

// File: contracts/tbills/RiverKYCStorage.sol



// SPDX-License-Identifier: BSD-3-Clause
pragma solidity ^0.8.10;
import "./IKycManager.sol";

// KYC Specific Storage
contract RiverKYCStorage {
    /**
     * @dev Event for when the KYC manager reference is set
     *
     * @param oldManager The old manager
     * @param newManager The new manager
     */
    event SetKYCManager(address oldManager, address newManager);

    /**
     * @notice Pointer to kycManager
     */
    IKycManager public kycManager;
}

// File: contracts/Unitroller.sol



// SPDX-License-Identifier: BSD-3-Clause
pragma solidity ^0.8.10;

import "./ErrorReporter.sol";
import "./ComptrollerStorage.sol";

/**
 * @title ComptrollerCore
 * @dev Storage for the comptroller is at this address, while execution is delegated to the `comptrollerImplementation`.
 * CTokens should reference this contract as their comptroller.
 */
contract Unitroller is UnitrollerAdminStorage, ComptrollerErrorReporter {
    /**
     * @notice Emitted when pendingComptrollerImplementation is changed
     */
    event NewPendingImplementation(
        address oldPendingImplementation,
        address newPendingImplementation
    );

    /**
     * @notice Emitted when pendingComptrollerImplementation is accepted, which means comptroller implementation is updated
     */
    event NewImplementation(
        address oldImplementation,
        address newImplementation
    );

    /**
     * @notice Emitted when pendingAdmin is changed
     */
    event NewPendingAdmin(address oldPendingAdmin, address newPendingAdmin);

    /**
     * @notice Emitted when pendingAdmin is accepted, which means admin is updated
     */
    event NewAdmin(address oldAdmin, address newAdmin);

    constructor() public {
        // Set admin to caller
        admin = msg.sender;
    }

    /*** Admin Functions ***/
    function _setPendingImplementation(
        address newPendingImplementation
    ) public returns (uint) {
        if (msg.sender != admin) {
            return
                fail(
                    Error.UNAUTHORIZED,
                    FailureInfo.SET_PENDING_IMPLEMENTATION_OWNER_CHECK
                );
        }

        address oldPendingImplementation = pendingComptrollerImplementation;

        pendingComptrollerImplementation = newPendingImplementation;

        emit NewPendingImplementation(
            oldPendingImplementation,
            pendingComptrollerImplementation
        );

        return uint(Error.NO_ERROR);
    }

    /**
     * @notice Accepts new implementation of comptroller. msg.sender must be pendingImplementation
     * @dev Admin function for new implementation to accept it's role as implementation
     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
     */
    function _acceptImplementation() public returns (uint) {
        // Check caller is pendingImplementation and pendingImplementation ≠ address(0)
        if (
            msg.sender != pendingComptrollerImplementation ||
            pendingComptrollerImplementation == address(0)
        ) {
            return
                fail(
                    Error.UNAUTHORIZED,
                    FailureInfo.ACCEPT_PENDING_IMPLEMENTATION_ADDRESS_CHECK
                );
        }

        // Save current values for inclusion in log
        address oldImplementation = comptrollerImplementation;
        address oldPendingImplementation = pendingComptrollerImplementation;

        comptrollerImplementation = pendingComptrollerImplementation;

        pendingComptrollerImplementation = address(0);

        emit NewImplementation(oldImplementation, comptrollerImplementation);
        emit NewPendingImplementation(
            oldPendingImplementation,
            pendingComptrollerImplementation
        );

        return uint(Error.NO_ERROR);
    }

    /**
     * @notice Begins transfer of admin rights. The newPendingAdmin must call `_acceptAdmin` to finalize the transfer.
     * @dev Admin function to begin change of admin. The newPendingAdmin must call `_acceptAdmin` to finalize the transfer.
     * @param newPendingAdmin New pending admin.
     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
     */
    function _setPendingAdmin(address newPendingAdmin) public returns (uint) {
        // Check caller = admin
        if (msg.sender != admin) {
            return
                fail(
                    Error.UNAUTHORIZED,
                    FailureInfo.SET_PENDING_ADMIN_OWNER_CHECK
                );
        }

        // Save current value, if any, for inclusion in log
        address oldPendingAdmin = pendingAdmin;

        // Store pendingAdmin with value newPendingAdmin
        pendingAdmin = newPendingAdmin;

        // Emit NewPendingAdmin(oldPendingAdmin, newPendingAdmin)
        emit NewPendingAdmin(oldPendingAdmin, newPendingAdmin);

        return uint(Error.NO_ERROR);
    }

    /**
     * @notice Accepts transfer of admin rights. msg.sender must be pendingAdmin
     * @dev Admin function for pending admin to accept role and update admin
     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
     */
    function _acceptAdmin() public returns (uint) {
        // Check caller is pendingAdmin and pendingAdmin ≠ address(0)
        if (msg.sender != pendingAdmin || msg.sender == address(0)) {
            return
                fail(
                    Error.UNAUTHORIZED,
                    FailureInfo.ACCEPT_ADMIN_PENDING_ADMIN_CHECK
                );
        }

        // Save current values for inclusion in log
        address oldAdmin = admin;
        address oldPendingAdmin = pendingAdmin;

        // Store admin with value pendingAdmin
        admin = pendingAdmin;

        // Clear the pending value
        pendingAdmin = address(0);

        emit NewAdmin(oldAdmin, admin);
        emit NewPendingAdmin(oldPendingAdmin, pendingAdmin);

        return uint(Error.NO_ERROR);
    }

    /**
     * @dev Delegates execution to an implementation contract.
     * It returns to the external caller whatever the implementation returns
     * or forwards reverts.
     */
    fallback() external payable {
        // delegate all other functions to current implementation
        (bool success, ) = comptrollerImplementation.delegatecall(msg.data);

        assembly {
            let free_mem_ptr := mload(0x40)
            returndatacopy(free_mem_ptr, 0, returndatasize())

            switch success
            case 0 {
                revert(free_mem_ptr, returndatasize())
            }
            default {
                return(free_mem_ptr, returndatasize())
            }
        }
    }
}