// File: contracts/BToken.sol



pragma solidity 0.5.16;

import "./ComptrollerInterface.sol";
import "./BTokenInterfaces.sol";
import "./ErrorReporter.sol";
import "./Exponential.sol";
import "./EIP20Interface.sol";
import "./EIP20NonStandardInterface.sol";
import "./InterestRateModel.sol";

/**
 * @title Blueberry's BToken Contract
 * @notice Abstract base for BTokens
 * @author Compound (Modifed by Blueberry)
 */
contract BToken is BTokenInterface, Exponential, 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_,
        uint256 initialExchangeRateMantissa_,
        string memory name_,
        string memory symbol_,
        uint8 decimals_
    ) public {
        require(msg.sender == admin, "admin only");
        require(accrualBlockNumber == 0 && borrowIndex == 0, "initialized");

        // Set initial exchange rate
        initialExchangeRateMantissa = initialExchangeRateMantissa_;
        require(initialExchangeRateMantissa > 0, "invalid exchange rate");

        // Set the comptroller
        uint256 err = _setComptroller(comptroller_);
        require(err == uint256(Error.NO_ERROR), "set 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 == uint256(Error.NO_ERROR), "set IRM 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 `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
        nonReentrant
        returns (bool)
    {
        return
            transferTokens(msg.sender, msg.sender, dst, amount) ==
            uint256(Error.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 nonReentrant returns (bool) {
        return
            transferTokens(msg.sender, src, dst, amount) ==
            uint256(Error.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 (-1 means infinite)
     * @return Whether or not the approval succeeded
     */
    function approve(address spender, uint256 amount) external 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
        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 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 returns (uint256) {
        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
        returns (
            uint256,
            uint256,
            uint256,
            uint256
        )
    {
        uint256 bTokenBalance = getBTokenBalanceInternal(account);
        uint256 borrowBalance = borrowBalanceStoredInternal(account);
        uint256 exchangeRateMantissa = exchangeRateStoredInternal();

        return (
            uint256(Error.NO_ERROR),
            bTokenBalance,
            borrowBalance,
            exchangeRateMantissa
        );
    }

    /**
     * @dev Function to simply retrieve block number
     *  This exists mainly for inheriting test contracts to stub this result.
     */
    function getBlockNumber() internal view returns (uint256) {
        return block.number;
    }

    /**
     * @notice Returns the current per-block borrow interest rate for this bToken
     * @return The borrow interest rate per block, scaled by 1e18
     */
    function borrowRatePerBlock() external view returns (uint256) {
        return
            interestRateModel.getBorrowRate(
                getCashPrior(),
                totalBorrows,
                totalReserves
            );
    }

    /**
     * @notice Returns the current per-block supply interest rate for this bToken
     * @return The supply interest rate per block, scaled by 1e18
     */
    function supplyRatePerBlock() external view returns (uint256) {
        return
            interestRateModel.getSupplyRate(
                getCashPrior(),
                totalBorrows,
                totalReserves,
                reserveFactorMantissa
            );
    }

    /**
     * @notice Returns the estimated per-block borrow interest rate for this bToken after some change
     * @return The borrow interest rate per block, scaled by 1e18
     */
    function estimateBorrowRatePerBlockAfterChange(uint256 change, bool repay)
        external
        view
        returns (uint256)
    {
        uint256 cashPriorNew;
        uint256 totalBorrowsNew;

        if (repay) {
            cashPriorNew = add_(getCashPrior(), change);
            totalBorrowsNew = sub_(totalBorrows, change);
        } else {
            cashPriorNew = sub_(getCashPrior(), change);
            totalBorrowsNew = add_(totalBorrows, change);
        }
        return
            interestRateModel.getBorrowRate(
                cashPriorNew,
                totalBorrowsNew,
                totalReserves
            );
    }

    /**
     * @notice Returns the estimated per-block supply interest rate for this bToken after some change
     * @return The supply interest rate per block, scaled by 1e18
     */
    function estimateSupplyRatePerBlockAfterChange(uint256 change, bool repay)
        external
        view
        returns (uint256)
    {
        uint256 cashPriorNew;
        uint256 totalBorrowsNew;

        if (repay) {
            cashPriorNew = add_(getCashPrior(), change);
            totalBorrowsNew = sub_(totalBorrows, change);
        } else {
            cashPriorNew = sub_(getCashPrior(), change);
            totalBorrowsNew = add_(totalBorrows, change);
        }

        return
            interestRateModel.getSupplyRate(
                cashPriorNew,
                totalBorrowsNew,
                totalReserves,
                reserveFactorMantissa
            );
    }

    /**
     * @notice Returns the current total borrows plus accrued interest
     * @return The total borrows with interest
     */
    function totalBorrowsCurrent() external nonReentrant returns (uint256) {
        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
        nonReentrant
        returns (uint256)
    {
        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
        returns (uint256)
    {
        return borrowBalanceStoredInternal(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 or 0 if error code is non-zero
     */
    function borrowBalanceStoredInternal(address account)
        internal
        view
        returns (uint256)
    {
        /* 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
         */
        uint256 principalTimesIndex = mul_(
            borrowSnapshot.principal,
            borrowIndex
        );
        uint256 result = div_(
            principalTimesIndex,
            borrowSnapshot.interestIndex
        );
        return result;
    }

    /**
     * @notice Accrue interest then return the up-to-date exchange rate
     * @return Calculated exchange rate scaled by 1e18
     */
    function exchangeRateCurrent() public nonReentrant returns (uint256) {
        accrueInterest();
        return exchangeRateStored();
    }

    /**
     * @notice Calculates the exchange rate from the underlying to the BToken
     * @dev This function does not accrue interest before calculating the exchange rate
     * @return Calculated exchange rate scaled by 1e18
     */
    function exchangeRateStored() public view returns (uint256) {
        return exchangeRateStoredInternal();
    }

    /**
     * @notice Calculates the exchange rate from the underlying to the BToken
     * @dev This function does not accrue interest before calculating the exchange rate
     * @return calculated exchange rate scaled by 1e18
     */
    function exchangeRateStoredInternal() internal view returns (uint256) {
        uint256 _totalSupply = totalSupply;
        if (_totalSupply == 0) {
            /*
             * If there are no tokens minted:
             *  exchangeRate = initialExchangeRate
             */
            return initialExchangeRateMantissa;
        } else {
            /*
             * Otherwise:
             *  exchangeRate = (totalCash + totalBorrows - totalReserves) / totalSupply
             */
            uint256 totalCash = getCashPrior();
            uint256 cashPlusBorrowsMinusReserves = sub_(
                add_(totalCash, totalBorrows),
                totalReserves
            );
            uint256 exchangeRate = div_(
                cashPlusBorrowsMinusReserves,
                Exp({mantissa: _totalSupply})
            );
            return exchangeRate;
        }
    }

    /**
     * @notice Get cash balance of this bToken in the underlying asset
     * @return The quantity of underlying asset owned by this contract
     */
    function getCash() external view returns (uint256) {
        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 returns (uint256) {
        /* Remember the initial block number */
        uint256 currentBlockNumber = getBlockNumber();
        uint256 accrualBlockNumberPrior = accrualBlockNumber;

        /* Short-circuit accumulating 0 interest */
        if (accrualBlockNumberPrior == currentBlockNumber) {
            return uint256(Error.NO_ERROR);
        }

        /* Read the previous values out of storage */
        uint256 cashPrior = getCashPrior();
        uint256 borrowsPrior = totalBorrows;
        uint256 reservesPrior = totalReserves;
        uint256 borrowIndexPrior = borrowIndex;

        /* Calculate the current borrow interest rate */
        uint256 borrowRateMantissa = interestRateModel.getBorrowRate(
            cashPrior,
            borrowsPrior,
            reservesPrior
        );
        require(
            borrowRateMantissa <= borrowRateMaxMantissa,
            "borrow rate too high"
        );

        /* Calculate the number of blocks elapsed since the last accrual */
        uint256 blockDelta = sub_(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
        );
        uint256 interestAccumulated = mul_ScalarTruncate(
            simpleInterestFactor,
            borrowsPrior
        );
        uint256 totalBorrowsNew = add_(interestAccumulated, borrowsPrior);
        uint256 totalReservesNew = mul_ScalarTruncateAddUInt(
            Exp({mantissa: reserveFactorMantissa}),
            interestAccumulated,
            reservesPrior
        );
        uint256 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 uint256(Error.NO_ERROR);
    }

    /**
     * @notice Sender supplies assets into the market and receives bTokens in exchange
     * @dev Accrues interest whether or not the operation succeeds, unless reverted
     * @param mintAmount The amount of the underlying asset to supply
     * @param isNative The amount is in native or not
     * @return (uint, uint) An error code (0=success, otherwise a failure, see ErrorReporter.sol), and the actual mint amount.
     */
    function mintInternal(uint256 mintAmount, bool isNative)
        internal
        nonReentrant
        returns (uint256, uint256)
    {
        accrueInterest();
        // mintFresh emits the actual Mint event if successful and logs on errors, so we don't need to
        return mintFresh(msg.sender, mintAmount, isNative);
    }

    /**
     * @notice Sender redeems bTokens in exchange for the underlying asset
     * @dev Accrues interest whether or not the operation succeeds, unless reverted
     * @param redeemTokens The number of bTokens to redeem into underlying
     * @param isNative The amount is in native or not
     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
     */
    function redeemInternal(uint256 redeemTokens, bool isNative)
        internal
        nonReentrant
        returns (uint256)
    {
        accrueInterest();
        // redeemFresh emits redeem-specific logs on errors, so we don't need to
        return redeemFresh(msg.sender, redeemTokens, 0, isNative);
    }

    /**
     * @notice Sender redeems bTokens 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 bTokens
     * @param isNative The amount is in native or not
     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
     */
    function redeemUnderlyingInternal(uint256 redeemAmount, bool isNative)
        internal
        nonReentrant
        returns (uint256)
    {
        accrueInterest();
        // redeemFresh emits redeem-specific logs on errors, so we don't need to
        return redeemFresh(msg.sender, 0, redeemAmount, isNative);
    }

    /**
     * @notice Sender borrows assets from the protocol to their own address
     * @param borrowAmount The amount of the underlying asset to borrow
     * @param isNative The amount is in native or not
     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
     */
    function borrowInternal(uint256 borrowAmount, bool isNative)
        internal
        nonReentrant
        returns (uint256)
    {
        accrueInterest();
        // borrowFresh emits borrow-specific logs on errors, so we don't need to
        return borrowFresh(msg.sender, borrowAmount, isNative);
    }

    struct BorrowLocalVars {
        MathError mathErr;
        uint256 accountBorrows;
        uint256 accountBorrowsNew;
        uint256 totalBorrowsNew;
    }

    /**
     * @notice Users borrow assets from the protocol to their own address
     * @param borrowAmount The amount of the underlying asset to borrow
     * @param isNative The amount is in native or not
     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
     */
    function borrowFresh(
        address payable borrower,
        uint256 borrowAmount,
        bool isNative
    ) internal returns (uint256) {
        /* Fail if borrow not allowed */
        require(
            comptroller.borrowAllowed(address(this), borrower, borrowAmount) ==
                0,
            "rejected"
        );

        /* Verify market's block number equals current block number */
        require(accrualBlockNumber == getBlockNumber(), "market is stale");

        /* Reverts if protocol has insufficient cash */
        require(getCashPrior() >= borrowAmount, "insufficient cash");

        BorrowLocalVars memory vars;

        /*
         * We calculate the new borrower and total borrow balances, failing on overflow:
         *  accountBorrowsNew = accountBorrows + borrowAmount
         *  totalBorrowsNew = totalBorrows + borrowAmount
         */
        vars.accountBorrows = borrowBalanceStoredInternal(borrower);
        vars.accountBorrowsNew = add_(vars.accountBorrows, borrowAmount);
        vars.totalBorrowsNew = add_(totalBorrows, borrowAmount);

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

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

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

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

        /* We call the defense hook */
        comptroller.borrowVerify(address(this), borrower, borrowAmount);

        return uint256(Error.NO_ERROR);
    }

    /**
     * @notice Sender repays their own borrow
     * @param repayAmount The amount to repay
     * @param isNative The amount is in native or not
     * @return (uint, uint) An error code (0=success, otherwise a failure, see ErrorReporter.sol), and the actual repayment amount.
     */
    function repayBorrowInternal(uint256 repayAmount, bool isNative)
        internal
        nonReentrant
        returns (uint256, uint256)
    {
        accrueInterest();
        // repayBorrowFresh emits repay-borrow-specific logs on errors, so we don't need to
        return repayBorrowFresh(msg.sender, msg.sender, repayAmount, isNative);
    }

    /**
     * @notice Sender repays a borrow belonging to borrower
     * @param borrower the account with the debt being payed off
     * @param repayAmount The amount to repay
     * @param isNative The amount is in native or not
     * @return (uint, uint) An error code (0=success, otherwise a failure, see ErrorReporter.sol), and the actual repayment amount.
     */
    function repayBorrowBehalfInternal(
        address borrower,
        uint256 repayAmount,
        bool isNative
    ) internal nonReentrant returns (uint256, uint256) {
        accrueInterest();
        // repayBorrowFresh emits repay-borrow-specific logs on errors, so we don't need to
        return repayBorrowFresh(msg.sender, borrower, repayAmount, isNative);
    }

    struct RepayBorrowLocalVars {
        Error err;
        MathError mathErr;
        uint256 repayAmount;
        uint256 borrowerIndex;
        uint256 accountBorrows;
        uint256 accountBorrowsNew;
        uint256 totalBorrowsNew;
        uint256 actualRepayAmount;
    }

    /**
     * @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
     * @param isNative The amount is in native or not
     * @return (uint, uint) An error code (0=success, otherwise a failure, see ErrorReporter.sol), and the actual repayment amount.
     */
    function repayBorrowFresh(
        address payer,
        address borrower,
        uint256 repayAmount,
        bool isNative
    ) internal returns (uint256, uint256) {
        /* Fail if repayBorrow not allowed */
        require(
            comptroller.repayBorrowAllowed(
                address(this),
                payer,
                borrower,
                repayAmount
            ) == 0,
            "rejected"
        );

        /* Verify market's block number equals current block number */
        require(accrualBlockNumber == getBlockNumber(), "market is stale");

        RepayBorrowLocalVars memory vars;

        /* We remember the original borrowerIndex for verification purposes */
        vars.borrowerIndex = accountBorrows[borrower].interestIndex;

        /* We fetch the amount the borrower owes, with accumulated interest */
        vars.accountBorrows = borrowBalanceStoredInternal(borrower);

        /* If repayAmount == -1, repayAmount = accountBorrows */
        if (repayAmount == uint256(-1)) {
            vars.repayAmount = vars.accountBorrows;
        } else {
            vars.repayAmount = repayAmount;
        }

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

        /*
         * We call doTransferIn for the payer and the repayAmount
         *  Note: The bToken must handle variations between ERC-20 and ETH underlying.
         *  On success, the bToken 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.
         */
        vars.actualRepayAmount = doTransferIn(
            payer,
            vars.repayAmount,
            isNative
        );

        /*
         * We calculate the new borrower and total borrow balances, failing on underflow:
         *  accountBorrowsNew = accountBorrows - actualRepayAmount
         *  totalBorrowsNew = totalBorrows - actualRepayAmount
         */
        vars.accountBorrowsNew = sub_(
            vars.accountBorrows,
            vars.actualRepayAmount
        );
        vars.totalBorrowsNew = sub_(totalBorrows, vars.actualRepayAmount);

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

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

        /* We call the defense hook */
        comptroller.repayBorrowVerify(
            address(this),
            payer,
            borrower,
            vars.actualRepayAmount,
            vars.borrowerIndex
        );

        return (uint256(Error.NO_ERROR), vars.actualRepayAmount);
    }

    /**
     * @notice The sender liquidates the borrowers collateral.
     *  The collateral seized is transferred to the liquidator.
     * @param borrower The borrower of this bToken to be liquidated
     * @param repayAmount The amount of the underlying borrowed asset to repay
     * @param bTokenCollateral The market in which to seize collateral from the borrower
     * @param isNative The amount is in native or not
     * @return (uint, uint) An error code (0=success, otherwise a failure, see ErrorReporter.sol), and the actual repayment amount.
     */
    function liquidateBorrowInternal(
        address borrower,
        uint256 repayAmount,
        BTokenInterface bTokenCollateral,
        bool isNative
    ) internal nonReentrant returns (uint256, uint256) {
        accrueInterest();
        require(
            bTokenCollateral.accrueInterest() == uint256(Error.NO_ERROR),
            "accrue interest failed"
        );

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

    struct LiquidateBorrowLocalVars {
        uint256 repayBorrowError;
        uint256 actualRepayAmount;
        uint256 amountSeizeError;
        uint256 seizeTokens;
    }

    /**
     * @notice The liquidator liquidates the borrowers collateral.
     *  The collateral seized is transferred to the liquidator.
     * @param borrower The borrower of this bToken to be liquidated
     * @param liquidator The address repaying the borrow and seizing collateral
     * @param bTokenCollateral The market in which to seize collateral from the borrower
     * @param repayAmount The amount of the underlying borrowed asset to repay
     * @param isNative The amount is in native or not
     * @return (uint, uint) An error code (0=success, otherwise a failure, see ErrorReporter.sol), and the actual repayment amount.
     */
    function liquidateBorrowFresh(
        address liquidator,
        address borrower,
        uint256 repayAmount,
        BTokenInterface bTokenCollateral,
        bool isNative
    ) internal returns (uint256, uint256) {
        /* Fail if liquidate not allowed */
        require(
            comptroller.liquidateBorrowAllowed(
                address(this),
                address(bTokenCollateral),
                liquidator,
                borrower,
                repayAmount
            ) == 0,
            "rejected"
        );

        /* Verify market's block number equals current block number */
        require(accrualBlockNumber == getBlockNumber(), "market is stale");

        /* Verify bTokenCollateral market's block number equals current block number */
        require(
            bTokenCollateral.accrualBlockNumber() == getBlockNumber(),
            "market is stale"
        );

        /* Fail if borrower = liquidator */
        require(borrower != liquidator, "invalid account pair");

        /* Fail if repayAmount = 0 or repayAmount = -1 */
        require(
            repayAmount > 0 && repayAmount != uint256(-1),
            "invalid amount"
        );

        LiquidateBorrowLocalVars memory vars;

        /* Fail if repayBorrow fails */
        (vars.repayBorrowError, vars.actualRepayAmount) = repayBorrowFresh(
            liquidator,
            borrower,
            repayAmount,
            isNative
        );
        require(
            vars.repayBorrowError == uint256(Error.NO_ERROR),
            "repay borrow failed"
        );

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

        /* We calculate the number of collateral tokens that will be seized */
        (vars.amountSeizeError, vars.seizeTokens) = comptroller
            .liquidateCalculateSeizeTokens(
                address(this),
                address(bTokenCollateral),
                vars.actualRepayAmount
            );
        require(
            vars.amountSeizeError == uint256(Error.NO_ERROR),
            "calculate seize amount failed"
        );

        /* Revert if borrower collateral token balance < seizeTokens */
        require(
            bTokenCollateral.balanceOf(borrower) >= vars.seizeTokens,
            "seize too much"
        );

        // If this is also the collateral, run seizeInternal to avoid re-entrancy, otherwise make an external call
        uint256 seizeError;
        if (address(bTokenCollateral) == address(this)) {
            seizeError = seizeInternal(
                address(this),
                liquidator,
                borrower,
                vars.seizeTokens
            );
        } else {
            seizeError = bTokenCollateral.seize(
                liquidator,
                borrower,
                vars.seizeTokens
            );
        }

        /* Revert if seize tokens fails (since we cannot be sure of side effects) */
        require(seizeError == uint256(Error.NO_ERROR), "token seizure failed");

        /* We emit a LiquidateBorrow event */
        emit LiquidateBorrow(
            liquidator,
            borrower,
            vars.actualRepayAmount,
            address(bTokenCollateral),
            vars.seizeTokens
        );

        /* We call the defense hook */
        comptroller.liquidateBorrowVerify(
            address(this),
            address(bTokenCollateral),
            liquidator,
            borrower,
            vars.actualRepayAmount,
            vars.seizeTokens
        );

        return (uint256(Error.NO_ERROR), vars.actualRepayAmount);
    }

    /**
     * @notice Transfers collateral tokens (this market) to the liquidator.
     * @dev Will fail unless called by another bToken during the process of liquidation.
     *  Its absolutely critical to use msg.sender as the borrowed bToken and not a parameter.
     * @param liquidator The account receiving seized collateral
     * @param borrower The account having collateral seized
     * @param seizeTokens The number of bTokens to seize
     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
     */
    function seize(
        address liquidator,
        address borrower,
        uint256 seizeTokens
    ) external nonReentrant returns (uint256) {
        return seizeInternal(msg.sender, liquidator, borrower, seizeTokens);
    }

    /*** 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
        returns (uint256)
    {
        // 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 uint256(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() external returns (uint256) {
        // 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 uint256(Error.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
        returns (uint256)
    {
        // Check caller is admin
        if (msg.sender != admin) {
            return
                fail(
                    Error.UNAUTHORIZED,
                    FailureInfo.SET_COMPTROLLER_OWNER_CHECK
                );
        }

        ComptrollerInterface oldComptroller = comptroller;
        // Ensure invoke comptroller.isComptroller() returns true
        require(newComptroller.isComptroller(), "not comptroller");

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

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

        return uint256(Error.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(uint256 newReserveFactorMantissa)
        external
        nonReentrant
        returns (uint256)
    {
        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(uint256 newReserveFactorMantissa)
        internal
        returns (uint256)
    {
        // Check caller is admin
        if (msg.sender != admin) {
            return
                fail(
                    Error.UNAUTHORIZED,
                    FailureInfo.SET_RESERVE_FACTOR_ADMIN_CHECK
                );
        }

        // Verify market's block number equals current block number
        if (accrualBlockNumber != getBlockNumber()) {
            return
                fail(
                    Error.MARKET_NOT_FRESH,
                    FailureInfo.SET_RESERVE_FACTOR_FRESH_CHECK
                );
        }

        // Check newReserveFactor ≤ maxReserveFactor
        if (newReserveFactorMantissa > reserveFactorMaxMantissa) {
            return
                fail(
                    Error.BAD_INPUT,
                    FailureInfo.SET_RESERVE_FACTOR_BOUNDS_CHECK
                );
        }

        uint256 oldReserveFactorMantissa = reserveFactorMantissa;
        reserveFactorMantissa = newReserveFactorMantissa;

        emit NewReserveFactor(
            oldReserveFactorMantissa,
            newReserveFactorMantissa
        );

        return uint256(Error.NO_ERROR);
    }

    /**
     * @notice Accrues interest and reduces reserves by transferring from msg.sender
     * @param addAmount Amount of addition to reserves
     * @param isNative The amount is in native or not
     * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
     */
    function _addReservesInternal(uint256 addAmount, bool isNative)
        internal
        nonReentrant
        returns (uint256)
    {
        accrueInterest();
        // _addReservesFresh emits reserve-addition-specific logs on errors, so we don't need to.
        (uint256 error, ) = _addReservesFresh(addAmount, isNative);
        return error;
    }

    /**
     * @notice Add reserves by transferring from caller
     * @dev Requires fresh interest accrual
     * @param addAmount Amount of addition to reserves
     * @param isNative The amount is in native or not
     * @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(uint256 addAmount, bool isNative)
        internal
        returns (uint256, uint256)
    {
        // totalReserves + actualAddAmount
        uint256 totalReservesNew;
        uint256 actualAddAmount;

        // We fail gracefully unless market's block number equals current block number
        if (accrualBlockNumber != getBlockNumber()) {
            return (
                fail(
                    Error.MARKET_NOT_FRESH,
                    FailureInfo.ADD_RESERVES_FRESH_CHECK
                ),
                actualAddAmount
            );
        }

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

        /*
         * We call doTransferIn for the caller and the addAmount
         *  Note: The bToken must handle variations between ERC-20 and ETH underlying.
         *  On success, the bToken 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, isNative);

        totalReservesNew = add_(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 (uint256(Error.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(uint256 reduceAmount)
        external
        nonReentrant
        returns (uint256)
    {
        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(uint256 reduceAmount)
        internal
        returns (uint256)
    {
        // totalReserves - reduceAmount
        uint256 totalReservesNew;

        // Check caller is admin
        if (msg.sender != admin) {
            return
                fail(
                    Error.UNAUTHORIZED,
                    FailureInfo.REDUCE_RESERVES_ADMIN_CHECK
                );
        }

        // We fail gracefully unless market's block number equals current block number
        if (accrualBlockNumber != getBlockNumber()) {
            return
                fail(
                    Error.MARKET_NOT_FRESH,
                    FailureInfo.REDUCE_RESERVES_FRESH_CHECK
                );
        }

        // Fail gracefully if protocol has insufficient underlying cash
        if (getCashPrior() < reduceAmount) {
            return
                fail(
                    Error.TOKEN_INSUFFICIENT_CASH,
                    FailureInfo.REDUCE_RESERVES_CASH_NOT_AVAILABLE
                );
        }

        // Check reduceAmount ≤ reserves[n] (totalReserves)
        if (reduceAmount > totalReserves) {
            return
                fail(Error.BAD_INPUT, FailureInfo.REDUCE_RESERVES_VALIDATION);
        }

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

        totalReservesNew = sub_(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.
        // Restrict reducing reserves in wrapped token. Implementations except `BWrappedNative` won't use parameter `isNative`.
        doTransferOut(admin, reduceAmount, false);

        emit ReservesReduced(admin, reduceAmount, totalReservesNew);

        return uint256(Error.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
        returns (uint256)
    {
        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 (uint256)
    {
        // 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) {
            return
                fail(
                    Error.UNAUTHORIZED,
                    FailureInfo.SET_INTEREST_RATE_MODEL_OWNER_CHECK
                );
        }

        // We fail gracefully unless market's block number equals current block number
        if (accrualBlockNumber != getBlockNumber()) {
            return
                fail(
                    Error.MARKET_NOT_FRESH,
                    FailureInfo.SET_INTEREST_RATE_MODEL_FRESH_CHECK
                );
        }

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

        // Ensure invoke newInterestRateModel.isInterestRateModel() returns true
        require(newInterestRateModel.isInterestRateModel(), "invalid IRM");

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

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

        return uint256(Error.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 returns (uint256);

    /**
     * @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,
        uint256 amount,
        bool isNative
    ) internal returns (uint256);

    /**
     * @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,
        uint256 amount,
        bool isNative
    ) internal;

    /**
     * @notice Transfer `tokens` tokens from `src` to `dst` by `spender`
     * @dev Called by both `transfer` and `transferFrom` internally
     */
    function transferTokens(
        address spender,
        address src,
        address dst,
        uint256 tokens
    ) internal returns (uint256);

    /**
     * @notice Get the account's bToken balances
     */
    function getBTokenBalanceInternal(address account)
        internal
        view
        returns (uint256);

    /**
     * @notice User supplies assets into the market and receives bTokens in exchange
     * @dev Assumes interest has already been accrued up to the current block
     */
    function mintFresh(
        address minter,
        uint256 mintAmount,
        bool isNative
    ) internal returns (uint256, uint256);

    /**
     * @notice User redeems bTokens in exchange for the underlying asset
     * @dev Assumes interest has already been accrued up to the current block
     */
    function redeemFresh(
        address payable redeemer,
        uint256 redeemTokensIn,
        uint256 redeemAmountIn,
        bool isNative
    ) internal returns (uint256);

    /**
     * @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 BToken.
     *  Its absolutely critical to use msg.sender as the seizer bToken and not a parameter.
     */
    function seizeInternal(
        address seizerToken,
        address liquidator,
        address borrower,
        uint256 seizeTokens
    ) internal returns (uint256);

    /*** 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/BTokenInterfaces.sol



pragma solidity 0.5.16;

import "./ComptrollerInterface.sol";
import "./InterestRateModel.sol";
import "./ERC3156FlashBorrowerInterface.sol";

contract BTokenStorage {
    /**
     * @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;

    /**
     * @notice Maximum borrow rate that can ever be applied (.0005% / block)
     */

    uint256 internal constant borrowRateMaxMantissa = 0.0005e16;

    /**
     * @notice Maximum fraction of interest that can be set aside for reserves
     */
    uint256 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-bToken operations
     */
    ComptrollerInterface public comptroller;

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

    /**
     * @notice Initial exchange rate used when minting the first BTokens (used when totalSupply = 0)
     */
    uint256 internal initialExchangeRateMantissa;

    /**
     * @notice Fraction of interest currently set aside for reserves
     */
    uint256 public reserveFactorMantissa;

    /**
     * @notice Block number that interest was last accrued at
     */
    uint256 public accrualBlockNumber;

    /**
     * @notice Accumulator of the total earned interest rate since the opening of the market
     */
    uint256 public borrowIndex;

    /**
     * @notice Total amount of outstanding borrows of the underlying in this market
     */
    uint256 public totalBorrows;

    /**
     * @notice Total amount of reserves of the underlying held in this market
     */
    uint256 public totalReserves;

    /**
     * @notice Total number of tokens in circulation
     */
    uint256 public totalSupply;

    /**
     * @notice Official record of token balances for each account
     */
    mapping(address => uint256) internal accountTokens;

    /**
     * @notice Approved token transfer amounts on behalf of others
     */
    mapping(address => mapping(address => uint256)) 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 {
        uint256 principal;
        uint256 interestIndex;
    }

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

contract BErc20Storage {
    /**
     * @notice Underlying asset for this BToken
     */
    address public underlying;

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

contract BSupplyCapStorage {
    /**
     * @notice Internal cash counter for this BToken. Should equal underlying.balanceOf(address(this)) for BERC20.
     */
    uint256 public internalCash;
}

contract BCollateralCapStorage {
    /**
     * @notice Total number of tokens used as collateral in circulation.
     */
    uint256 public totalCollateralTokens;

    /**
     * @notice Record of token balances which could be treated as collateral for each account.
     *         If collateral cap is not set, the value should be equal to accountTokens.
     */
    mapping(address => uint256) public accountCollateralTokens;

    /**
     * @notice Check if accountCollateralTokens have been initialized.
     */
    mapping(address => bool) public isCollateralTokenInit;

    /**
     * @notice Collateral cap for this BToken, zero for no cap.
     */
    uint256 public collateralCap;
}

/*** Interface ***/

contract BTokenInterface is BTokenStorage {
    /**
     * @notice Indicator that this is a BToken contract (for inspection)
     */
    bool public constant isBToken = true;

    /*** Market Events ***/

    /**
     * @notice Event emitted when interest is accrued
     */
    event AccrueInterest(
        uint256 cashPrior,
        uint256 interestAccumulated,
        uint256 borrowIndex,
        uint256 totalBorrows
    );

    /**
     * @notice Event emitted when tokens are minted
     */
    event Mint(address minter, uint256 mintAmount, uint256 mintTokens);

    /**
     * @notice Event emitted when tokens are redeemed
     */
    event Redeem(address redeemer, uint256 redeemAmount, uint256 redeemTokens);

    /**
     * @notice Event emitted when underlying is borrowed
     */
    event Borrow(
        address borrower,
        uint256 borrowAmount,
        uint256 accountBorrows,
        uint256 totalBorrows
    );

    /**
     * @notice Event emitted when a borrow is repaid
     */
    event RepayBorrow(
        address payer,
        address borrower,
        uint256 repayAmount,
        uint256 accountBorrows,
        uint256 totalBorrows
    );

    /**
     * @notice Event emitted when a borrow is liquidated
     */
    event LiquidateBorrow(
        address liquidator,
        address borrower,
        uint256 repayAmount,
        address bTokenCollateral,
        uint256 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(
        uint256 oldReserveFactorMantissa,
        uint256 newReserveFactorMantissa
    );

    /**
     * @notice Event emitted when the reserves are added
     */
    event ReservesAdded(
        address benefactor,
        uint256 addAmount,
        uint256 newTotalReserves
    );

    /**
     * @notice Event emitted when the reserves are reduced
     */
    event ReservesReduced(
        address admin,
        uint256 reduceAmount,
        uint256 newTotalReserves
    );

    /**
     * @notice EIP20 Transfer event
     */
    event Transfer(address indexed from, address indexed to, uint256 amount);

    /**
     * @notice EIP20 Approval event
     */
    event Approval(
        address indexed owner,
        address indexed spender,
        uint256 amount
    );

    /**
     * @notice Failure event
     */
    event Failure(uint256 error, uint256 info, uint256 detail);

    /*** User Interface ***/

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

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

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

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

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

    function balanceOfUnderlying(address owner) external returns (uint256);

    function getAccountSnapshot(address account)
        external
        view
        returns (
            uint256,
            uint256,
            uint256,
            uint256
        );

    function borrowRatePerBlock() external view returns (uint256);

    function supplyRatePerBlock() external view returns (uint256);

    function totalBorrowsCurrent() external returns (uint256);

    function borrowBalanceCurrent(address account) external returns (uint256);

    function borrowBalanceStored(address account) public view returns (uint256);

    function exchangeRateCurrent() public returns (uint256);

    function exchangeRateStored() public view returns (uint256);

    function getCash() external view returns (uint256);

    function accrueInterest() public returns (uint256);

    function seize(
        address liquidator,
        address borrower,
        uint256 seizeTokens
    ) external returns (uint256);

    /*** Admin Functions ***/

    function _setPendingAdmin(address payable newPendingAdmin)
        external
        returns (uint256);

    function _acceptAdmin() external returns (uint256);

    function _setComptroller(ComptrollerInterface newComptroller)
        public
        returns (uint256);

    function _setReserveFactor(uint256 newReserveFactorMantissa)
        external
        returns (uint256);

    function _reduceReserves(uint256 reduceAmount) external returns (uint256);

    function _setInterestRateModel(InterestRateModel newInterestRateModel)
        public
        returns (uint256);
}

contract BErc20Interface is BErc20Storage {
    /*** User Interface ***/

    function mint(uint256 mintAmount) external returns (uint256);

    function redeem(uint256 redeemTokens) external returns (uint256);

    function redeemUnderlying(uint256 redeemAmount) external returns (uint256);

    function borrow(uint256 borrowAmount) external returns (uint256);

    function repayBorrow(uint256 repayAmount) external returns (uint256);

    function repayBorrowBehalf(address borrower, uint256 repayAmount)
        external
        returns (uint256);

    function liquidateBorrow(
        address borrower,
        uint256 repayAmount,
        BTokenInterface bTokenCollateral
    ) external returns (uint256);

    function _addReserves(uint256 addAmount) external returns (uint256);
}

contract BWrappedNativeInterface is BErc20Interface {
    /**
     * @notice Flash loan fee ratio
     */
    uint256 public constant flashFeeBips = 3;

    /*** Market Events ***/

    /**
     * @notice Event emitted when a flashloan occurred
     */
    event Flashloan(
        address indexed receiver,
        uint256 amount,
        uint256 totalFee,
        uint256 reservesFee
    );

    /*** User Interface ***/

    function mintNative() external payable returns (uint256);

    function redeemNative(uint256 redeemTokens) external returns (uint256);

    function redeemUnderlyingNative(uint256 redeemAmount)
        external
        returns (uint256);

    function borrowNative(uint256 borrowAmount) external returns (uint256);

    function repayBorrowNative() external payable returns (uint256);

    function repayBorrowBehalfNative(address borrower)
        external
        payable
        returns (uint256);

    function liquidateBorrowNative(
        address borrower,
        BTokenInterface bTokenCollateral
    ) external payable returns (uint256);

    function flashLoan(
        ERC3156FlashBorrowerInterface receiver,
        address initiator,
        uint256 amount,
        bytes calldata data
    ) external returns (bool);

    function _addReservesNative() external payable returns (uint256);

    function collateralCap() external view returns (uint256);

    function totalCollateralTokens() external view returns (uint256);
}

contract BCapableErc20Interface is BErc20Interface, BSupplyCapStorage {
    /**
     * @notice Flash loan fee ratio
     */
    uint256 public constant flashFeeBips = 3;

    /*** Market Events ***/

    /**
     * @notice Event emitted when a flashloan occurred
     */
    event Flashloan(
        address indexed receiver,
        uint256 amount,
        uint256 totalFee,
        uint256 reservesFee
    );

    /*** User Interface ***/

    function gulp() external;
}

contract BCollateralCapErc20Interface is
    BCapableErc20Interface,
    BCollateralCapStorage
{
    /*** Admin Events ***/

    /**
     * @notice Event emitted when collateral cap is set
     */
    event NewCollateralCap(address token, uint256 newCap);

    /**
     * @notice Event emitted when user collateral is changed
     */
    event UserCollateralChanged(address account, uint256 newCollateralTokens);

    /*** User Interface ***/

    function registerCollateral(address account) external returns (uint256);

    function unregisterCollateral(address account) external;

    function flashLoan(
        ERC3156FlashBorrowerInterface receiver,
        address initiator,
        uint256 amount,
        bytes calldata data
    ) external returns (bool);

    /*** Admin Functions ***/

    function _setCollateralCap(uint256 newCollateralCap) external;
}

contract BDelegatorInterface {
    /**
     * @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
    ) public;
}

contract BDelegateInterface {
    /**
     * @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) public;

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

/*** External interface ***/

/**
 * @title Flash loan receiver interface
 */
interface IFlashloanReceiver {
    function executeOperation(
        address sender,
        address underlying,
        uint256 amount,
        uint256 fee,
        bytes calldata params
    ) external;
}

// File: contracts/CarefulMath.sol



pragma solidity 0.5.16;

/**
 * @title Careful Math
 * @author Compound
 * @notice Derived from OpenZeppelin's SafeMath library
 *         https://github.com/OpenZeppelin/openzeppelin-solidity/blob/master/contracts/math/SafeMath.sol
 */
contract CarefulMath {
    /**
     * @dev Possible error codes that we can return
     */
    enum MathError {
        NO_ERROR,
        DIVISION_BY_ZERO,
        INTEGER_OVERFLOW,
        INTEGER_UNDERFLOW
    }

    /**
     * @dev Multiplies two numbers, returns an error on overflow.
     */
    function mulUInt(uint256 a, uint256 b)
        internal
        pure
        returns (MathError, uint256)
    {
        if (a == 0) {
            return (MathError.NO_ERROR, 0);
        }

        uint256 c = a * b;

        if (c / a != b) {
            return (MathError.INTEGER_OVERFLOW, 0);
        } else {
            return (MathError.NO_ERROR, c);
        }
    }

    /**
     * @dev Integer division of two numbers, truncating the quotient.
     */
    function divUInt(uint256 a, uint256 b)
        internal
        pure
        returns (MathError, uint256)
    {
        if (b == 0) {
            return (MathError.DIVISION_BY_ZERO, 0);
        }

        return (MathError.NO_ERROR, a / b);
    }

    /**
     * @dev Subtracts two numbers, returns an error on overflow (i.e. if subtrahend is greater than minuend).
     */
    function subUInt(uint256 a, uint256 b)
        internal
        pure
        returns (MathError, uint256)
    {
        if (b <= a) {
            return (MathError.NO_ERROR, a - b);
        } else {
            return (MathError.INTEGER_UNDERFLOW, 0);
        }
    }

    /**
     * @dev Adds two numbers, returns an error on overflow.
     */
    function addUInt(uint256 a, uint256 b)
        internal
        pure
        returns (MathError, uint256)
    {
        uint256 c = a + b;

        if (c >= a) {
            return (MathError.NO_ERROR, c);
        } else {
            return (MathError.INTEGER_OVERFLOW, 0);
        }
    }

    /**
     * @dev add a and b and then subtract c
     */
    function addThenSubUInt(
        uint256 a,
        uint256 b,
        uint256 c
    ) internal pure returns (MathError, uint256) {
        (MathError err0, uint256 sum) = addUInt(a, b);

        if (err0 != MathError.NO_ERROR) {
            return (err0, 0);
        }

        return subUInt(sum, c);
    }
}

// File: contracts/Comptroller.sol



pragma solidity 0.5.16;

import "./BToken.sol";
import "./ErrorReporter.sol";
import "./Exponential.sol";
import "./PriceOracle/PriceOracle.sol";
import "./ComptrollerInterface.sol";
import "./ComptrollerStorage.sol";
import "./LiquidityMiningInterface.sol";
import "./Unitroller.sol";

/**
 * @title Blueberry's Comptroller Contract
 * @author Compound (modified by Blueberry)
 */
contract Comptroller is
    ComptrollerV1Storage,
    ComptrollerInterface,
    ComptrollerErrorReporter,
    Exponential
{
    /// @notice Emitted when an admin supports a market
    event MarketListed(BToken bToken);

    /// @notice Emitted when an admin delists a market
    event MarketDelisted(BToken bToken, bool force);

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

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

    /// @notice Emitted when close factor is changed by admin
    event NewCloseFactor(
        uint256 oldCloseFactorMantissa,
        uint256 newCloseFactorMantissa
    );

    /// @notice Emitted when a collateral factor is changed by admin
    event NewCollateralFactor(
        BToken bToken,
        uint256 oldCollateralFactorMantissa,
        uint256 newCollateralFactorMantissa
    );

    /// @notice Emitted when liquidation incentive is changed by admin
    event NewLiquidationIncentive(
        uint256 oldLiquidationIncentiveMantissa,
        uint256 newLiquidationIncentiveMantissa
    );

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

    /// @notice Emitted when guardian is changed
    event NewGuardian(address oldGuardian, address newGuardian);

    /// @notice Emitted when liquidity mining module is changed
    event NewLiquidityMining(
        address oldLiquidityMining,
        address newLiquidityMining
    );

    /// @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(BToken bToken, string action, bool pauseState);

    /// @notice Emitted when borrow cap for a bToken is changed
    event NewBorrowCap(BToken indexed bToken, uint256 newBorrowCap);

    /// @notice Emitted when supply cap for a bToken is changed
    event NewSupplyCap(BToken indexed bToken, uint256 newSupplyCap);

    /// @notice Emitted when protocol's credit limit has changed
    event CreditLimitChanged(
        address protocol,
        address market,
        uint256 creditLimit
    );

    /// @notice Emitted when bToken version is changed
    event NewBTokenVersion(
        BToken bToken,
        Version oldVersion,
        Version newVersion
    );

    /// @notice Emitted when credit limit manager is changed
    event NewCreditLimitManager(
        address oldCreditLimitManager,
        address newCreditLimitManager
    );

    // No collateralFactorMantissa may exceed this value
    uint256 internal constant collateralFactorMaxMantissa = 0.9e18; // 0.9

    constructor() public {
        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 (BToken[] memory)
    {
        BToken[] 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 bToken The bToken to check
     * @return True if the account is in the asset, otherwise false.
     */
    function checkMembership(address account, BToken bToken)
        external
        view
        returns (bool)
    {
        return markets[address(bToken)].accountMembership[account];
    }

    /**
     * @notice Add assets to be included in account liquidity calculation
     * @param bTokens The list of addresses of the bToken markets to be enabled
     * @return Success indicator for whether each corresponding market was entered
     */
    function enterMarkets(address[] memory bTokens)
        public
        returns (uint256[] memory)
    {
        uint256 len = bTokens.length;

        uint256[] memory results = new uint256[](len);
        for (uint256 i = 0; i < len; i++) {
            BToken bToken = BToken(bTokens[i]);

            results[i] = uint256(addToMarketInternal(bToken, msg.sender));
        }

        return results;
    }

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

        require(marketToJoin.isListed, "market not listed");

        if (marketToJoin.version == Version.COLLATERALCAP) {
            // register collateral for the borrower if the token is CollateralCap version.
            BCollateralCapErc20Interface(address(bToken)).registerCollateral(
                borrower
            );
        }

        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(bToken);

        emit MarketEntered(bToken, 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 bTokenAddress The address of the asset to be removed
     * @return Whether or not the account successfully exited the market
     */
    function exitMarket(address bTokenAddress) external returns (uint256) {
        BToken bToken = BToken(bTokenAddress);
        /* Get sender tokensHeld and amountOwed underlying from the bToken */
        (uint256 oErr, uint256 tokensHeld, uint256 amountOwed, ) = bToken
            .getAccountSnapshot(msg.sender);
        require(oErr == 0, "exitMarket: getAccountSnapshot failed"); // semi-opaque error code

        /* Fail if the sender has a borrow balance */
        require(amountOwed == 0, "nonzero borrow balance");

        /* Fail if the sender is not permitted to redeem all of their tokens */
        require(
            redeemAllowedInternal(bTokenAddress, msg.sender, tokensHeld) == 0,
            "failed to exit market"
        );

        Market storage marketToExit = markets[bTokenAddress];

        if (marketToExit.version == Version.COLLATERALCAP) {
            BCollateralCapErc20Interface(bTokenAddress).unregisterCollateral(
                msg.sender
            );
        }

        /* Return true if the sender is not already ‘in’ the market */
        if (!marketToExit.accountMembership[msg.sender]) {
            return uint256(Error.NO_ERROR);
        }

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

        /* Delete bToken from the account’s list of assets */
        // load into memory for faster iteration
        BToken[] memory userAssetList = accountAssets[msg.sender];
        uint256 len = userAssetList.length;
        uint256 assetIndex = len;
        for (uint256 i = 0; i < len; i++) {
            if (userAssetList[i] == bToken) {
                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
        BToken[] storage storedList = accountAssets[msg.sender];
        if (assetIndex != storedList.length - 1) {
            storedList[assetIndex] = storedList[storedList.length - 1];
        }
        storedList.length--;

        emit MarketExited(bToken, msg.sender);

        return uint256(Error.NO_ERROR);
    }

    /**
     * @notice Return a specific market is listed or not
     * @param bTokenAddress The address of the asset to be checked
     * @return Whether or not the market is listed
     */
    function isMarketListed(address bTokenAddress) public view returns (bool) {
        return markets[bTokenAddress].isListed;
    }

    /**
     * @notice Return a specific market is listed or delisted
     * @param bTokenAddress The address of the asset to be checked
     * @return Whether or not the market is listed or delisted
     */
    function isMarketListedOrDelisted(address bTokenAddress)
        public
        view
        returns (bool)
    {
        return
            markets[bTokenAddress].isListed || isMarketDelisted[bTokenAddress];
    }

    /**
     * @notice Return the credit limit of a specific protocol
     * @dev This function shouldn't be called. It exists only for backward compatibility.
     * @param protocol The address of the protocol
     * @return The credit
     */
    function creditLimits(address protocol) public view returns (uint256) {
        protocol; // Shh
        return 0;
    }

    /**
     * @notice Return the credit limit of a specific protocol for a specific market
     * @param protocol The address of the protocol
     * @param market The market
     * @return The credit
     */
    function creditLimits(address protocol, address market)
        public
        view
        returns (uint256)
    {
        return _creditLimits[protocol][market];
    }

    /*** Policy Hooks ***/

    /**
     * @notice Checks if the account should be allowed to mint tokens in the given market
     * @param bToken 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 bToken,
        address minter,
        uint256 mintAmount
    ) external returns (uint256) {
        // Pausing is a very serious situation - we revert to sound the alarms
        require(!mintGuardianPaused[bToken], "mint is paused");
        require(!isCreditAccount(minter, bToken), "credit account cannot mint");

        require(isMarketListed(bToken), "market not listed");

        uint256 supplyCap = supplyCaps[bToken];
        // Supply cap of 0 corresponds to unlimited supplying
        if (supplyCap != 0) {
            uint256 totalCash = BToken(bToken).getCash();
            uint256 totalBorrows = BToken(bToken).totalBorrows();
            uint256 totalReserves = BToken(bToken).totalReserves();
            // totalSupplies = totalCash + totalBorrows - totalReserves
            (MathError mathErr, uint256 totalSupplies) = addThenSubUInt(
                totalCash,
                totalBorrows,
                totalReserves
            );
            require(mathErr == MathError.NO_ERROR, "totalSupplies failed");

            uint256 nextTotalSupplies = add_(totalSupplies, mintAmount);
            require(nextTotalSupplies < supplyCap, "market supply cap reached");
        }

        return uint256(Error.NO_ERROR);
    }

    /**
     * @notice Validates mint and reverts on rejection. May emit logs.
     * @param bToken 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 bToken,
        address minter,
        uint256 actualMintAmount,
        uint256 mintTokens
    ) external {
        // Shh - currently unused
        bToken;
        minter;
        actualMintAmount;
        mintTokens;

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

    /**
     * @notice Checks if the account should be allowed to redeem tokens in the given market
     * @param bToken The market to verify the redeem against
     * @param redeemer The account which would redeem the tokens
     * @param redeemTokens The number of bTokens 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 bToken,
        address redeemer,
        uint256 redeemTokens
    ) external returns (uint256) {
        return redeemAllowedInternal(bToken, redeemer, redeemTokens);
    }

    function redeemAllowedInternal(
        address bToken,
        address redeemer,
        uint256 redeemTokens
    ) internal view returns (uint256) {
        require(isMarketListedOrDelisted(bToken), "market not listed");
        require(
            !isCreditAccount(redeemer, bToken),
            "credit account cannot redeem"
        );

        /* If the redeemer is not 'in' the market, then we can bypass the liquidity check */
        if (!markets[bToken].accountMembership[redeemer]) {
            return uint256(Error.NO_ERROR);
        }

        /* Otherwise, perform a hypothetical liquidity check to guard against shortfall */
        (
            Error err,
            ,
            uint256 shortfall
        ) = getHypotheticalAccountLiquidityInternal(
                redeemer,
                BToken(bToken),
                redeemTokens,
                0
            );
        require(err == Error.NO_ERROR, "failed to get account liquidity");
        require(shortfall == 0, "insufficient liquidity");

        return uint256(Error.NO_ERROR);
    }

    /**
     * @notice Validates redeem and reverts on rejection. May emit logs.
     * @param bToken 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 bToken,
        address redeemer,
        uint256 redeemAmount,
        uint256 redeemTokens
    ) external {
        // Shh - currently unused
        bToken;
        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 bToken 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 bToken,
        address borrower,
        uint256 borrowAmount
    ) external returns (uint256) {
        // Pausing is a very serious situation - we revert to sound the alarms
        require(!borrowGuardianPaused[bToken], "borrow is paused");

        require(isMarketListed(bToken), "market not listed");

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

            // attempt to add borrower to the market
            require(
                addToMarketInternal(BToken(bToken), borrower) == Error.NO_ERROR,
                "failed to add market"
            );

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

        require(oracle.getUnderlyingPrice(BToken(bToken)) != 0, "price error");

        uint256 borrowCap = borrowCaps[bToken];
        // Borrow cap of 0 corresponds to unlimited borrowing
        if (borrowCap != 0) {
            uint256 totalBorrows = BToken(bToken).totalBorrows();
            uint256 nextTotalBorrows = add_(totalBorrows, borrowAmount);
            require(nextTotalBorrows < borrowCap, "market borrow cap reached");
        }

        uint256 creditLimit = _creditLimits[borrower][bToken];
        // If the borrower is a credit account, check the credit limit instead of account liquidity.
        if (creditLimit > 0) {
            (uint256 oErr, , uint256 borrowBalance, ) = BToken(bToken)
                .getAccountSnapshot(borrower);
            require(oErr == 0, "snapshot error");
            require(
                creditLimit >= add_(borrowBalance, borrowAmount),
                "insufficient credit limit"
            );
        } else {
            (
                Error err,
                ,
                uint256 shortfall
            ) = getHypotheticalAccountLiquidityInternal(
                    borrower,
                    BToken(bToken),
                    0,
                    borrowAmount
                );
            require(err == Error.NO_ERROR, "failed to get account liquidity");
            require(shortfall == 0, "insufficient liquidity");
        }
        return uint256(Error.NO_ERROR);
    }

    /**
     * @notice Validates borrow and reverts on rejection. May emit logs.
     * @param bToken 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 bToken,
        address borrower,
        uint256 borrowAmount
    ) external {
        // Shh - currently unused
        bToken;
        borrower;
        borrowAmount;

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

    /**
     * @notice Checks if the account should be allowed to repay a borrow in the given market
     * @param bToken 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 bToken,
        address payer,
        address borrower,
        uint256 repayAmount
    ) external returns (uint256) {
        // Shh - currently unused
        repayAmount;

        require(isMarketListedOrDelisted(bToken), "market not listed");

        if (isCreditAccount(borrower, bToken)) {
            require(
                borrower == payer,
                "cannot repay on behalf of credit account"
            );
        }

        return uint256(Error.NO_ERROR);
    }

    /**
     * @notice Validates repayBorrow and reverts on rejection. May emit logs.
     * @param bToken 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 bToken,
        address payer,
        address borrower,
        uint256 actualRepayAmount,
        uint256 borrowerIndex
    ) external {
        // Shh - currently unused
        bToken;
        payer;
        borrower;
        actualRepayAmount;
        borrowerIndex;

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

    /**
     * @notice Checks if the liquidation should be allowed to occur
     * @param bTokenBorrowed Asset which was borrowed by the borrower
     * @param bTokenCollateral 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 bTokenBorrowed,
        address bTokenCollateral,
        address liquidator,
        address borrower,
        uint256 repayAmount
    ) external returns (uint256) {
        require(
            !isCreditAccount(borrower, bTokenBorrowed),
            "cannot liquidate credit account"
        );

        // Shh - currently unused
        liquidator;

        require(
            isMarketListedOrDelisted(bTokenBorrowed) &&
                isMarketListedOrDelisted(bTokenCollateral),
            "market not listed"
        );

        /* The borrower must have shortfall in order to be liquidatable */
        (Error err, , uint256 shortfall) = getAccountLiquidityInternal(
            borrower
        );
        require(err == Error.NO_ERROR, "failed to get account liquidity");
        require(shortfall > 0, "insufficient shortfall");

        /* The liquidator may not repay more than what is allowed by the closeFactor */
        uint256 borrowBalance = BToken(bTokenBorrowed).borrowBalanceStored(
            borrower
        );
        uint256 maxClose = mul_ScalarTruncate(
            Exp({mantissa: closeFactorMantissa}),
            borrowBalance
        );
        if (repayAmount > maxClose) {
            return uint256(Error.TOO_MUCH_REPAY);
        }

        return uint256(Error.NO_ERROR);
    }

    /**
     * @notice Validates liquidateBorrow and reverts on rejection. May emit logs.
     * @param bTokenBorrowed Asset which was borrowed by the borrower
     * @param bTokenCollateral 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 bTokenBorrowed,
        address bTokenCollateral,
        address liquidator,
        address borrower,
        uint256 actualRepayAmount,
        uint256 seizeTokens
    ) external {
        // Shh - currently unused
        bTokenBorrowed;
        bTokenCollateral;
        liquidator;
        borrower;
        actualRepayAmount;
        seizeTokens;

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

    /**
     * @notice Checks if the seizing of assets should be allowed to occur
     * @param bTokenCollateral Asset which was used as collateral and will be seized
     * @param bTokenBorrowed 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 bTokenCollateral,
        address bTokenBorrowed,
        address liquidator,
        address borrower,
        uint256 seizeTokens
    ) external returns (uint256) {
        // Pausing is a very serious situation - we revert to sound the alarms
        require(!seizeGuardianPaused, "seize is paused");
        require(
            !isCreditAccount(borrower, bTokenBorrowed),
            "cannot seize from credit account"
        );

        // Shh - currently unused
        liquidator;
        seizeTokens;

        require(
            isMarketListedOrDelisted(bTokenBorrowed) &&
                isMarketListedOrDelisted(bTokenCollateral),
            "market not listed"
        );
        require(
            BToken(bTokenCollateral).comptroller() ==
                BToken(bTokenBorrowed).comptroller(),
            "comptroller mismatched"
        );

        return uint256(Error.NO_ERROR);
    }

    /**
     * @notice Validates seize and reverts on rejection. May emit logs.
     * @param bTokenCollateral Asset which was used as collateral and will be seized
     * @param bTokenBorrowed 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 bTokenCollateral,
        address bTokenBorrowed,
        address liquidator,
        address borrower,
        uint256 seizeTokens
    ) external {
        // Shh - currently unused
        bTokenCollateral;
        bTokenBorrowed;
        liquidator;
        borrower;
        seizeTokens;

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

    /**
     * @notice Checks if the account should be allowed to transfer tokens in the given market
     * @param bToken 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 bTokens to transfer
     * @return 0 if the transfer is allowed, otherwise a semi-opaque error code (See ErrorReporter.sol)
     */
    function transferAllowed(
        address bToken,
        address src,
        address dst,
        uint256 transferTokens
    ) external returns (uint256) {
        // Pausing is a very serious situation - we revert to sound the alarms
        require(!transferGuardianPaused, "transfer is paused");
        require(
            !isCreditAccount(dst, bToken),
            "cannot transfer to a credit account"
        );

        // Currently the only consideration is whether or not
        //  the src is allowed to redeem this many tokens
        return redeemAllowedInternal(bToken, src, transferTokens);
    }

    /**
     * @notice Validates transfer and reverts on rejection. May emit logs.
     * @param bToken Asset being transferred
     * @param src The account which sources the tokens
     * @param dst The account which receives the tokens
     * @param transferTokens The number of bTokens to transfer
     */
    function transferVerify(
        address bToken,
        address src,
        address dst,
        uint256 transferTokens
    ) external {
        // Shh - currently unused
        bToken;
        src;
        dst;
        transferTokens;

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

    /**
     * @notice Checks if the account should be allowed to transfer tokens in the given market
     * @param bToken The market to verify the transfer against
     * @param receiver The account which receives the tokens
     * @param amount The amount of the tokens
     * @param params The other parameters
     */

    function flashloanAllowed(
        address bToken,
        address receiver,
        uint256 amount,
        bytes calldata params
    ) external view returns (bool) {
        return !flashloanGuardianPaused[bToken];
    }

    /**
     * @notice Update BToken's version.
     * @param bToken Version of the asset being updated
     * @param newVersion The new version
     */
    function updateBTokenVersion(address bToken, Version newVersion) external {
        require(msg.sender == bToken, "bToken only");

        // This function will be called when a new BToken implementation becomes active.
        // If a new BToken is newly created, this market is not listed yet. The version of
        // this market will be taken care of when calling `_supportMarket`.
        if (isMarketListed(bToken)) {
            Version oldVersion = markets[bToken].version;
            markets[bToken].version = newVersion;

            emit NewBTokenVersion(BToken(bToken), oldVersion, newVersion);
        }
    }

    /**
     * @notice Check if the account is a credit account
     * @param account The account needs to be checked
     * @param bToken The market
     * @return The account is a credit account or not
     */
    function isCreditAccount(address account, address bToken)
        public
        view
        returns (bool)
    {
        return _creditLimits[account][bToken] > 0;
    }

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

    /**
     * @dev Local vars for avoiding stack-depth limits in calculating account liquidity.
     *  Note that `bTokenBalance` is the number of bTokens the account owns in the market,
     *  whereas `borrowBalance` is the amount of underlying that the account has borrowed.
     */
    struct AccountLiquidityLocalVars {
        uint256 sumCollateral;
        uint256 sumBorrowPlusEffects;
        uint256 bTokenBalance;
        uint256 borrowBalance;
        uint256 exchangeRateMantissa;
        uint256 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 (
            uint256,
            uint256,
            uint256
        )
    {
        (
            Error err,
            uint256 liquidity,
            uint256 shortfall
        ) = getHypotheticalAccountLiquidityInternal(account, BToken(0), 0, 0);

        return (uint256(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,
            uint256,
            uint256
        )
    {
        return
            getHypotheticalAccountLiquidityInternal(account, BToken(0), 0, 0);
    }

    /**
     * @notice Determine what the account liquidity would be if the given amounts were redeemed/borrowed
     * @param bTokenModify 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 bTokenModify,
        uint256 redeemTokens,
        uint256 borrowAmount
    )
        public
        view
        returns (
            uint256,
            uint256,
            uint256
        )
    {
        (
            Error err,
            uint256 liquidity,
            uint256 shortfall
        ) = getHypotheticalAccountLiquidityInternal(
                account,
                BToken(bTokenModify),
                redeemTokens,
                borrowAmount
            );
        return (uint256(err), liquidity, shortfall);
    }

    /**
     * @notice Determine what the account liquidity would be if the given amounts were redeemed/borrowed
     * @param bTokenModify 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 bToken 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,
        BToken bTokenModify,
        uint256 redeemTokens,
        uint256 borrowAmount
    )
        internal
        view
        returns (
            Error,
            uint256,
            uint256
        )
    {
        AccountLiquidityLocalVars memory vars; // Holds all our calculation results
        uint256 oErr;

        // For each asset the account is in
        BToken[] memory assets = accountAssets[account];
        for (uint256 i = 0; i < assets.length; i++) {
            BToken asset = assets[i];

            // Skip the asset if it is not listed or soft delisted.
            if (!isMarketListedOrDelisted(address(asset))) {
                continue;
            }

            // Read the balances and exchange rate from the bToken
            (
                oErr,
                vars.bTokenBalance,
                vars.borrowBalance,
                vars.exchangeRateMantissa
            ) = asset.getAccountSnapshot(account);
            require(oErr == 0, "snapshot error");

            // Unlike compound protocol, getUnderlyingPrice is relatively expensive because we use ChainLink as our primary price feed.
            // If user has no supply / borrow balance on this asset, and user is not redeeming / borrowing this asset, skip it.
            if (
                vars.bTokenBalance == 0 &&
                vars.borrowBalance == 0 &&
                asset != bTokenModify
            ) {
                continue;
            }

            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);
            require(vars.oraclePriceMantissa > 0, "price error");
            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 * bTokenBalance
            vars.sumCollateral = mul_ScalarTruncateAddUInt(
                vars.tokensToDenom,
                vars.bTokenBalance,
                vars.sumCollateral
            );

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

            // Calculate effects of interacting with bTokenModify
            if (asset == bTokenModify) {
                // 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 bToken.liquidateBorrowFresh)
     * @param bTokenBorrowed The address of the borrowed bToken
     * @param bTokenCollateral The address of the collateral bToken
     * @param actualRepayAmount The amount of bTokenBorrowed underlying to convert into bTokenCollateral tokens
     * @return (errorCode, number of bTokenCollateral tokens to be seized in a liquidation)
     */
    function liquidateCalculateSeizeTokens(
        address bTokenBorrowed,
        address bTokenCollateral,
        uint256 actualRepayAmount
    ) external view returns (uint256, uint256) {
        /* Read oracle prices for borrowed and collateral markets */
        uint256 priceBorrowedMantissa = oracle.getUnderlyingPrice(
            BToken(bTokenBorrowed)
        );
        uint256 priceCollateralMantissa = oracle.getUnderlyingPrice(
            BToken(bTokenCollateral)
        );
        require(
            priceBorrowedMantissa > 0 && priceCollateralMantissa > 0,
            "price error"
        );

        /*
         * 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)
         */
        uint256 exchangeRateMantissa = BToken(bTokenCollateral)
            .exchangeRateStored(); // Note: reverts on error
        Exp memory numerator = mul_(
            Exp({mantissa: liquidationIncentiveMantissa}),
            Exp({mantissa: priceBorrowedMantissa})
        );
        Exp memory denominator = mul_(
            Exp({mantissa: priceCollateralMantissa}),
            Exp({mantissa: exchangeRateMantissa})
        );
        Exp memory ratio = div_(numerator, denominator);
        uint256 seizeTokens = mul_ScalarTruncate(ratio, actualRepayAmount);

        return (uint256(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 (uint256) {
        // 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);

        return uint256(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. (See ErrorReporter for details)
     */
    function _setCloseFactor(uint256 newCloseFactorMantissa)
        external
        returns (uint256)
    {
        // Check caller is admin
        if (msg.sender != admin) {
            return
                fail(
                    Error.UNAUTHORIZED,
                    FailureInfo.SET_CLOSE_FACTOR_OWNER_CHECK
                );
        }

        uint256 oldCloseFactorMantissa = closeFactorMantissa;
        closeFactorMantissa = newCloseFactorMantissa;
        emit NewCloseFactor(oldCloseFactorMantissa, closeFactorMantissa);

        return uint256(Error.NO_ERROR);
    }

    /**
     * @notice Sets the collateralFactor for a market
     * @dev Admin function to set per-market collateralFactor
     * @param bToken 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(
        BToken bToken,
        uint256 newCollateralFactorMantissa
    ) external returns (uint256) {
        // 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(bToken)];
        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(bToken) == 0
        ) {
            return
                fail(
                    Error.PRICE_ERROR,
                    FailureInfo.SET_COLLATERAL_FACTOR_WITHOUT_PRICE
                );
        }

        // Set market's collateral factor to new collateral factor, remember old value
        uint256 oldCollateralFactorMantissa = market.collateralFactorMantissa;
        market.collateralFactorMantissa = newCollateralFactorMantissa;

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

        return uint256(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(uint256 newLiquidationIncentiveMantissa)
        external
        returns (uint256)
    {
        // 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
        uint256 oldLiquidationIncentiveMantissa = liquidationIncentiveMantissa;

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

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

        return uint256(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 bToken The address of the market (token) to list
     * @param version The version of the market (token)
     * @return uint 0=success, otherwise a failure. (See enum Error for details)
     */
    function _supportMarket(BToken bToken, Version version)
        external
        returns (uint256)
    {
        require(msg.sender == admin, "admin only");
        require(
            !isMarketListedOrDelisted(address(bToken)),
            "market already listed or delisted"
        );

        bToken.isBToken(); // Sanity check to make sure its really a BToken

        markets[address(bToken)] = Market({
            isListed: true,
            collateralFactorMantissa: 0,
            version: version
        });

        _addMarketInternal(address(bToken));

        emit MarketListed(bToken);

        return uint256(Error.NO_ERROR);
    }

    /**
     * @notice Remove the market from the markets mapping
     * @param bToken The address of the market (token) to delist
     * @param force If True, hard delist the market by not adding to `isMarketDelisted`
     */
    function _delistMarket(BToken bToken, bool force) external {
        require(msg.sender == admin, "admin only");
        require(
            markets[address(bToken)].collateralFactorMantissa == 0,
            "market has collateral"
        );
        require(
            mintGuardianPaused[address(bToken)] &&
                borrowGuardianPaused[address(bToken)] &&
                flashloanGuardianPaused[address(bToken)],
            "market not paused"
        );

        if (!force) {
            // Soft delist.
            require(isMarketListed(address(bToken)), "market not listed");
            isMarketDelisted[address(bToken)] = true;
        } else {
            // Hard delist.
            require(
                isMarketListedOrDelisted(address(bToken)),
                "market not listed or soft delisted"
            );
        }
        delete markets[address(bToken)];

        for (uint256 i = 0; i < allMarkets.length; i++) {
            if (allMarkets[i] == bToken) {
                allMarkets[i] = allMarkets[allMarkets.length - 1];
                delete allMarkets[allMarkets.length - 1];
                allMarkets.length--;
                break;
            }
        }

        emit MarketDelisted(bToken, force);
    }

    function _addMarketInternal(address bToken) internal {
        for (uint256 i = 0; i < allMarkets.length; i++) {
            require(allMarkets[i] != BToken(bToken), "market already added");
        }
        allMarkets.push(BToken(bToken));
    }

    /**
     * @notice Set the given supply caps for the given bToken markets. Supplying that brings total supplies to or above supply cap will revert.
     * @dev Admin or guardian function to set the supply caps. A supply cap of 0 corresponds to unlimited supplying. If the total borrows
     *      already exceeded the cap, it will prevent anyone to borrow.
     * @param bTokens The addresses of the markets (tokens) to change the supply caps for
     * @param newSupplyCaps The new supply cap values in underlying to be set. A value of 0 corresponds to unlimited supplying.
     */
    function _setMarketSupplyCaps(
        BToken[] calldata bTokens,
        uint256[] calldata newSupplyCaps
    ) external {
        require(
            msg.sender == admin || msg.sender == guardian,
            "admin or guardian only"
        );

        uint256 numMarkets = bTokens.length;
        uint256 numSupplyCaps = newSupplyCaps.length;

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

        for (uint256 i = 0; i < numMarkets; i++) {
            supplyCaps[address(bTokens[i])] = newSupplyCaps[i];
            emit NewSupplyCap(bTokens[i], newSupplyCaps[i]);
        }
    }

    /**
     * @notice Set the given borrow caps for the given bToken markets. Borrowing that brings total borrows to or above borrow cap will revert.
     * @dev Admin or guardian function to set the borrow caps. A borrow cap of 0 corresponds to unlimited borrowing. If the total supplies
     *      already exceeded the cap, it will prevent anyone to mint.
     * @param bTokens 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(
        BToken[] calldata bTokens,
        uint256[] calldata newBorrowCaps
    ) external {
        require(
            msg.sender == admin || msg.sender == guardian,
            "admin or guardian only"
        );

        uint256 numMarkets = bTokens.length;
        uint256 numBorrowCaps = newBorrowCaps.length;

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

        for (uint256 i = 0; i < numMarkets; i++) {
            borrowCaps[address(bTokens[i])] = newBorrowCaps[i];
            emit NewBorrowCap(bTokens[i], newBorrowCaps[i]);
        }
    }

    /**
     * @notice Admin function to change the Guardian
     * @param newGuardian The address of the new Guardian
     * @return uint 0=success, otherwise a failure. (See enum Error for details)
     */
    function _setGuardian(address newGuardian) public returns (uint256) {
        if (msg.sender != admin) {
            return
                fail(
                    Error.UNAUTHORIZED,
                    FailureInfo.SET_PAUSE_GUARDIAN_OWNER_CHECK
                );
        }

        // Save current value for inclusion in log
        address oldGuardian = guardian;

        // Store guardian with value newGuardian
        guardian = newGuardian;

        // Emit NewGuardian(OldGuardian, NewGuardian)
        emit NewGuardian(oldGuardian, guardian);

        return uint256(Error.NO_ERROR);
    }

    /**
     * @notice Admin function to set the liquidity mining module address
     * @dev Removing the liquidity mining module address could cause the inconsistency in the LM module.
     * @param newLiquidityMining The address of the new liquidity mining module
     */
    function _setLiquidityMining(address newLiquidityMining) external {
        require(msg.sender == admin, "admin only");
        require(
            LiquidityMiningInterface(newLiquidityMining).comptroller() ==
                address(this),
            "mismatch comptroller"
        );

        // Save current value for inclusion in log
        address oldLiquidityMining = liquidityMining;

        // Store liquidityMining with value newLiquidityMining
        liquidityMining = newLiquidityMining;

        // Emit NewLiquidityMining(OldLiquidityMining, NewLiquidityMining)
        emit NewLiquidityMining(oldLiquidityMining, liquidityMining);
    }

    /**
     * @notice Admin function to set the credit limit manager address
     * @param newCreditLimitManager The address of the new credit limit manager
     */
    function _setCreditLimitManager(address newCreditLimitManager) external {
        require(msg.sender == admin, "admin only");

        // Save current value for inclusion in log
        address oldCreditLimitManager = creditLimitManager;

        // Store creditLimitManager with value newCreditLimitManager
        creditLimitManager = newCreditLimitManager;

        // Emit NewCreditLimitManager(oldCreditLimitManager, newCreditLimitManager)
        emit NewCreditLimitManager(oldCreditLimitManager, creditLimitManager);
    }

    function _setMintPaused(BToken bToken, bool state) public returns (bool) {
        require(isMarketListed(address(bToken)), "market not listed");
        require(
            msg.sender == guardian || msg.sender == admin,
            "guardian or admin only"
        );
        require(msg.sender == admin || state == true, "admin only");

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

    function _setBorrowPaused(BToken bToken, bool state) public returns (bool) {
        require(isMarketListed(address(bToken)), "market not listed");
        require(
            msg.sender == guardian || msg.sender == admin,
            "guardian or admin only"
        );
        require(msg.sender == admin || state == true, "admin only");

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

    function _setFlashloanPaused(BToken bToken, bool state)
        public
        returns (bool)
    {
        require(isMarketListed(address(bToken)), "market not listed");
        require(
            msg.sender == guardian || msg.sender == admin,
            "guardian or admin only"
        );
        require(msg.sender == admin || state == true, "admin only");

        flashloanGuardianPaused[address(bToken)] = state;
        emit ActionPaused(bToken, "Flashloan", state);
        return state;
    }

    function _setTransferPaused(bool state) public returns (bool) {
        require(
            msg.sender == guardian || msg.sender == admin,
            "guardian or admin only"
        );
        require(msg.sender == admin || state == true, "admin only");

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

    function _setSeizePaused(bool state) public returns (bool) {
        require(
            msg.sender == guardian || msg.sender == admin,
            "guardian or admin only"
        );
        require(msg.sender == admin || state == true, "admin only");

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

    function _become(Unitroller unitroller) public {
        require(msg.sender == unitroller.admin(), "unitroller admin only");
        require(unitroller._acceptImplementation() == 0, "unauthorized");
    }

    /**
     * @notice Sets protocol's credit limit by market
     * @dev Setting credit limit to 0 would change the protocol to a normal account
     * @param protocol The address of the protocol
     * @param market The market
     * @param creditLimit The credit limit
     */
    function _setCreditLimit(
        address protocol,
        address market,
        uint256 creditLimit
    ) public {
        require(
            msg.sender == admin || msg.sender == creditLimitManager,
            "admin or credit limit manager only"
        );

        _setCreditLimitInternal(protocol, market, creditLimit);
    }

    /**
     * @notice Pause protocol's credit limit by market
     * @param protocol The address of the protocol
     * @param market The market
     */
    function _pauseCreditLimit(address protocol, address market) public {
        require(msg.sender == guardian, "guardian only");

        // We set the credit limit to a very small amount (1 Wei) to avoid the protocol becoming a normal account.
        // Normal account could be liquidated or repaid, which might cause some additional problem.
        _setCreditLimitInternal(protocol, market, 1);
    }

    function _setCreditLimitInternal(
        address protocol,
        address market,
        uint256 creditLimit
    ) internal {
        require(isMarketListed(market), "market not listed");

        _creditLimits[protocol][market] = creditLimit;
        emit CreditLimitChanged(protocol, market, creditLimit);
    }

    /**
     * @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 (BToken[] memory) {
        return allMarkets;
    }

    function getBlockNumber() public view returns (uint256) {
        return block.number;
    }
}

// File: contracts/ComptrollerInterface.sol



pragma solidity 0.5.16;

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 bTokens)
        external
        returns (uint256[] memory);

    function exitMarket(address bToken) external returns (uint256);

    /*** Policy Hooks ***/

    function mintAllowed(
        address bToken,
        address minter,
        uint256 mintAmount
    ) external returns (uint256);

    function mintVerify(
        address bToken,
        address minter,
        uint256 mintAmount,
        uint256 mintTokens
    ) external;

    function redeemAllowed(
        address bToken,
        address redeemer,
        uint256 redeemTokens
    ) external returns (uint256);

    function redeemVerify(
        address bToken,
        address redeemer,
        uint256 redeemAmount,
        uint256 redeemTokens
    ) external;

    function borrowAllowed(
        address bToken,
        address borrower,
        uint256 borrowAmount
    ) external returns (uint256);

    function borrowVerify(
        address bToken,
        address borrower,
        uint256 borrowAmount
    ) external;

    function repayBorrowAllowed(
        address bToken,
        address payer,
        address borrower,
        uint256 repayAmount
    ) external returns (uint256);

    function repayBorrowVerify(
        address bToken,
        address payer,
        address borrower,
        uint256 repayAmount,
        uint256 borrowerIndex
    ) external;

    function liquidateBorrowAllowed(
        address bTokenBorrowed,
        address bTokenCollateral,
        address liquidator,
        address borrower,
        uint256 repayAmount
    ) external returns (uint256);

    function liquidateBorrowVerify(
        address bTokenBorrowed,
        address bTokenCollateral,
        address liquidator,
        address borrower,
        uint256 repayAmount,
        uint256 seizeTokens
    ) external;

    function seizeAllowed(
        address bTokenCollateral,
        address bTokenBorrowed,
        address liquidator,
        address borrower,
        uint256 seizeTokens
    ) external returns (uint256);

    function seizeVerify(
        address bTokenCollateral,
        address bTokenBorrowed,
        address liquidator,
        address borrower,
        uint256 seizeTokens
    ) external;

    function transferAllowed(
        address bToken,
        address src,
        address dst,
        uint256 transferTokens
    ) external returns (uint256);

    function transferVerify(
        address bToken,
        address src,
        address dst,
        uint256 transferTokens
    ) external;

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

    function liquidateCalculateSeizeTokens(
        address bTokenBorrowed,
        address bTokenCollateral,
        uint256 repayAmount
    ) external view returns (uint256, uint256);
}

// File: contracts/ComptrollerStorage.sol



pragma solidity 0.5.16;

import "./BToken.sol";
import "./PriceOracle/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
     */
    uint256 public closeFactorMantissa;

    /**
     * @notice Multiplier representing the discount on collateral that a liquidator receives
     */
    uint256 public liquidationIncentiveMantissa;

    /**
     * @notice Per-account mapping of "assets you are in"
     */
    mapping(address => BToken[]) public accountAssets;

    enum Version {
        VANILLA,
        COLLATERALCAP,
        WRAPPEDNATIVE
    }

    struct Market {
        /// @notice Whether or not this market is listed
        bool isListed;
        /**
         * @notice 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.
         */
        uint256 collateralFactorMantissa;
        /// @notice Per-market mapping of "accounts in this asset"
        mapping(address => bool) accountMembership;
        /// @notice BToken version
        Version version;
    }

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

    /**
     * @notice The 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 guardian;
    bool public _mintGuardianPaused;
    bool public _borrowGuardianPaused;
    bool public transferGuardianPaused;
    bool public seizeGuardianPaused;
    mapping(address => bool) public mintGuardianPaused;
    mapping(address => bool) public borrowGuardianPaused;

    struct CompMarketState {
        /// @notice The market's last updated compBorrowIndex or compSupplyIndex
        uint224 index;
        /// @notice The block number the index was last updated at
        uint32 block;
    }

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

    /// @notice The portion of compRate that each market currently receives
    /// @dev This storage is deprecated.
    mapping(address => uint256) public compSpeeds;

    /// @notice The COMP market supply state for each market
    /// @dev This storage is deprecated.
    mapping(address => CompMarketState) public compSupplyState;

    /// @notice The COMP market borrow state for each market
    /// @dev This storage is deprecated.
    mapping(address => CompMarketState) public compBorrowState;

    /// @notice The COMP borrow index for each market for each supplier as of the last time they accrued COMP
    /// @dev This storage is deprecated.
    mapping(address => mapping(address => uint256)) public compSupplierIndex;

    /// @notice The COMP borrow index for each market for each borrower as of the last time they accrued COMP
    /// @dev This storage is deprecated.
    mapping(address => mapping(address => uint256)) public compBorrowerIndex;

    /// @notice The COMP accrued but not yet transferred to each user
    /// @dev This storage is deprecated.
    mapping(address => uint256) public compAccrued;

    /// @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 bToken address. Defaults to zero which corresponds to unlimited borrowing.
    mapping(address => uint256) public borrowCaps;

    /// @notice The supplyCapGuardian can set supplyCaps to any number for any market. Lowering the supply cap could disable supplying to the given market.
    address public supplyCapGuardian;

    /// @notice Supply caps enforced by mintAllowed for each bToken address. Defaults to zero which corresponds to unlimited supplying.
    mapping(address => uint256) public supplyCaps;

    /// @notice creditLimits allowed specific protocols to borrow and repay without collateral.
    /// @dev This storage is deprecated.
    mapping(address => uint256) internal _oldCreditLimits;

    /// @notice flashloanGuardianPaused can pause flash loan as a safety mechanism.
    mapping(address => bool) public flashloanGuardianPaused;

    /// @notice liquidityMining the liquidity mining module that handles the LM rewards distribution.
    address public liquidityMining;

    /// @notice creditLimits allowed specific protocols to borrow and repay specific markets without collateral.
    mapping(address => mapping(address => uint256)) internal _creditLimits;

    /// @notice isMarketDelisted records the market which has been delisted by us.
    mapping(address => bool) public isMarketDelisted;

    /// @notice creditLimitManager is the role who is in charge of increasing the credit limit.
    address public creditLimitManager;
}

// File: contracts/EIP20Interface.sol



pragma solidity 0.5.16;

/**
 * @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 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 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 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 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 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



pragma solidity 0.5.16;

/**
 * @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 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 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 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/ERC3156FlashBorrowerInterface.sol



pragma solidity 0.5.16;

interface ERC3156FlashBorrowerInterface {
    /**
     * @dev Receive a flash loan.
     * @param initiator The initiator of the loan.
     * @param token The loan currency.
     * @param amount The amount of tokens lent.
     * @param fee The additional amount of tokens to repay.
     * @param data Arbitrary data structure, intended to contain user-defined parameters.
     * @return The keccak256 hash of "ERC3156FlashBorrower.onFlashLoan"
     */
    function onFlashLoan(
        address initiator,
        address token,
        uint256 amount,
        uint256 fee,
        bytes calldata data
    ) external returns (bytes32);
}

// File: contracts/ErrorReporter.sol



pragma solidity 0.5.16;

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(uint256 error, uint256 info, uint256 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 (uint256) {
        emit Failure(uint256(err), uint256(info), 0);

        return uint256(err);
    }

    /**
     * @dev use this when reporting an opaque error from an upgradeable collaborator contract
     */
    function failOpaque(
        Error err,
        FailureInfo info,
        uint256 opaqueError
    ) internal returns (uint256) {
        emit Failure(uint256(err), uint256(info), opaqueError);

        return uint256(err);
    }
}

contract TokenErrorReporter {
    enum Error {
        NO_ERROR,
        UNAUTHORIZED,
        BAD_INPUT,
        COMPTROLLER_REJECTION,
        COMPTROLLER_CALCULATION_ERROR,
        INTEREST_RATE_MODEL_ERROR,
        INVALID_ACCOUNT_PAIR,
        INVALID_CLOSE_AMOUNT_REQUESTED,
        INVALID_COLLATERAL_FACTOR,
        MATH_ERROR,
        MARKET_NOT_FRESH,
        MARKET_NOT_LISTED,
        TOKEN_INSUFFICIENT_ALLOWANCE,
        TOKEN_INSUFFICIENT_BALANCE,
        TOKEN_INSUFFICIENT_CASH,
        TOKEN_TRANSFER_IN_FAILED,
        TOKEN_TRANSFER_OUT_FAILED
    }

    /*
     * Note: FailureInfo (but not Error) is kept in alphabetical order
     *       This is because FailureInfo grows significantly faster, and
     *       the order of Error has some meaning, while the order of FailureInfo
     *       is entirely arbitrary.
     */
    enum FailureInfo {
        ACCEPT_ADMIN_PENDING_ADMIN_CHECK,
        ACCRUE_INTEREST_BORROW_RATE_CALCULATION_FAILED,
        BORROW_ACCRUE_INTEREST_FAILED,
        BORROW_CASH_NOT_AVAILABLE,
        BORROW_FRESHNESS_CHECK,
        BORROW_MARKET_NOT_LISTED,
        BORROW_COMPTROLLER_REJECTION,
        LIQUIDATE_ACCRUE_BORROW_INTEREST_FAILED,
        LIQUIDATE_ACCRUE_COLLATERAL_INTEREST_FAILED,
        LIQUIDATE_COLLATERAL_FRESHNESS_CHECK,
        LIQUIDATE_COMPTROLLER_REJECTION,
        LIQUIDATE_COMPTROLLER_CALCULATE_AMOUNT_SEIZE_FAILED,
        LIQUIDATE_CLOSE_AMOUNT_IS_UINT_MAX,
        LIQUIDATE_CLOSE_AMOUNT_IS_ZERO,
        LIQUIDATE_FRESHNESS_CHECK,
        LIQUIDATE_LIQUIDATOR_IS_BORROWER,
        LIQUIDATE_REPAY_BORROW_FRESH_FAILED,
        LIQUIDATE_SEIZE_COMPTROLLER_REJECTION,
        LIQUIDATE_SEIZE_LIQUIDATOR_IS_BORROWER,
        LIQUIDATE_SEIZE_TOO_MUCH,
        MINT_ACCRUE_INTEREST_FAILED,
        MINT_COMPTROLLER_REJECTION,
        MINT_FRESHNESS_CHECK,
        MINT_TRANSFER_IN_FAILED,
        MINT_TRANSFER_IN_NOT_POSSIBLE,
        REDEEM_ACCRUE_INTEREST_FAILED,
        REDEEM_COMPTROLLER_REJECTION,
        REDEEM_FRESHNESS_CHECK,
        REDEEM_TRANSFER_OUT_NOT_POSSIBLE,
        REDUCE_RESERVES_ACCRUE_INTEREST_FAILED,
        REDUCE_RESERVES_ADMIN_CHECK,
        REDUCE_RESERVES_CASH_NOT_AVAILABLE,
        REDUCE_RESERVES_FRESH_CHECK,
        REDUCE_RESERVES_VALIDATION,
        REPAY_BEHALF_ACCRUE_INTEREST_FAILED,
        REPAY_BORROW_ACCRUE_INTEREST_FAILED,
        REPAY_BORROW_COMPTROLLER_REJECTION,
        REPAY_BORROW_FRESHNESS_CHECK,
        REPAY_BORROW_TRANSFER_IN_NOT_POSSIBLE,
        SET_COLLATERAL_FACTOR_OWNER_CHECK,
        SET_COLLATERAL_FACTOR_VALIDATION,
        SET_COMPTROLLER_OWNER_CHECK,
        SET_INTEREST_RATE_MODEL_ACCRUE_INTEREST_FAILED,
        SET_INTEREST_RATE_MODEL_FRESH_CHECK,
        SET_INTEREST_RATE_MODEL_OWNER_CHECK,
        SET_MAX_ASSETS_OWNER_CHECK,
        SET_ORACLE_MARKET_NOT_LISTED,
        SET_PENDING_ADMIN_OWNER_CHECK,
        SET_RESERVE_FACTOR_ACCRUE_INTEREST_FAILED,
        SET_RESERVE_FACTOR_ADMIN_CHECK,
        SET_RESERVE_FACTOR_FRESH_CHECK,
        SET_RESERVE_FACTOR_BOUNDS_CHECK,
        TRANSFER_COMPTROLLER_REJECTION,
        TRANSFER_NOT_ALLOWED,
        ADD_RESERVES_ACCRUE_INTEREST_FAILED,
        ADD_RESERVES_FRESH_CHECK,
        ADD_RESERVES_TRANSFER_IN_NOT_POSSIBLE
    }

    /**
     * @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(uint256 error, uint256 info, uint256 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 (uint256) {
        emit Failure(uint256(err), uint256(info), 0);

        return uint256(err);
    }

    /**
     * @dev use this when reporting an opaque error from an upgradeable collaborator contract
     */
    function failOpaque(
        Error err,
        FailureInfo info,
        uint256 opaqueError
    ) internal returns (uint256) {
        emit Failure(uint256(err), uint256(info), opaqueError);

        return uint256(err);
    }
}

// File: contracts/Exponential.sol



pragma solidity 0.5.16;

import "./CarefulMath.sol";

/**
 * @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 Exponential is CarefulMath {
    uint256 constant expScale = 1e18;
    uint256 constant doubleScale = 1e36;
    uint256 constant halfExpScale = expScale / 2;
    uint256 constant mantissaOne = expScale;

    struct Exp {
        uint256 mantissa;
    }

    struct Double {
        uint256 mantissa;
    }

    /**
     * @dev Creates an exponential from numerator and denominator values.
     *      Note: Returns an error if (`num` * 10e18) > MAX_INT,
     *            or if `denom` is zero.
     */
    function getExp(uint256 num, uint256 denom)
        internal
        pure
        returns (MathError, Exp memory)
    {
        (MathError err0, uint256 scaledNumerator) = mulUInt(num, expScale);
        if (err0 != MathError.NO_ERROR) {
            return (err0, Exp({mantissa: 0}));
        }

        (MathError err1, uint256 rational) = divUInt(scaledNumerator, denom);
        if (err1 != MathError.NO_ERROR) {
            return (err1, Exp({mantissa: 0}));
        }

        return (MathError.NO_ERROR, Exp({mantissa: rational}));
    }

    /**
     * @dev Adds two exponentials, returning a new exponential.
     */
    function addExp(Exp memory a, Exp memory b)
        internal
        pure
        returns (MathError, Exp memory)
    {
        (MathError error, uint256 result) = addUInt(a.mantissa, b.mantissa);

        return (error, Exp({mantissa: result}));
    }

    /**
     * @dev Subtracts two exponentials, returning a new exponential.
     */
    function subExp(Exp memory a, Exp memory b)
        internal
        pure
        returns (MathError, Exp memory)
    {
        (MathError error, uint256 result) = subUInt(a.mantissa, b.mantissa);

        return (error, Exp({mantissa: result}));
    }

    /**
     * @dev Multiply an Exp by a scalar, returning a new Exp.
     */
    function mulScalar(Exp memory a, uint256 scalar)
        internal
        pure
        returns (MathError, Exp memory)
    {
        (MathError err0, uint256 scaledMantissa) = mulUInt(a.mantissa, scalar);
        if (err0 != MathError.NO_ERROR) {
            return (err0, Exp({mantissa: 0}));
        }

        return (MathError.NO_ERROR, Exp({mantissa: scaledMantissa}));
    }

    /**
     * @dev Multiply an Exp by a scalar, then truncate to return an unsigned integer.
     */
    function mulScalarTruncate(Exp memory a, uint256 scalar)
        internal
        pure
        returns (MathError, uint256)
    {
        (MathError err, Exp memory product) = mulScalar(a, scalar);
        if (err != MathError.NO_ERROR) {
            return (err, 0);
        }

        return (MathError.NO_ERROR, truncate(product));
    }

    /**
     * @dev Multiply an Exp by a scalar, truncate, then add an to an unsigned integer, returning an unsigned integer.
     */
    function mulScalarTruncateAddUInt(
        Exp memory a,
        uint256 scalar,
        uint256 addend
    ) internal pure returns (MathError, uint256) {
        (MathError err, Exp memory product) = mulScalar(a, scalar);
        if (err != MathError.NO_ERROR) {
            return (err, 0);
        }

        return addUInt(truncate(product), addend);
    }

    /**
     * @dev Multiply an Exp by a scalar, then truncate to return an unsigned integer.
     */
    function mul_ScalarTruncate(Exp memory a, uint256 scalar)
        internal
        pure
        returns (uint256)
    {
        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,
        uint256 scalar,
        uint256 addend
    ) internal pure returns (uint256) {
        Exp memory product = mul_(a, scalar);
        return add_(truncate(product), addend);
    }

    /**
     * @dev Divide an Exp by a scalar, returning a new Exp.
     */
    function divScalar(Exp memory a, uint256 scalar)
        internal
        pure
        returns (MathError, Exp memory)
    {
        (MathError err0, uint256 descaledMantissa) = divUInt(
            a.mantissa,
            scalar
        );
        if (err0 != MathError.NO_ERROR) {
            return (err0, Exp({mantissa: 0}));
        }

        return (MathError.NO_ERROR, Exp({mantissa: descaledMantissa}));
    }

    /**
     * @dev Divide a scalar by an Exp, returning a new Exp.
     */
    function divScalarByExp(uint256 scalar, Exp memory divisor)
        internal
        pure
        returns (MathError, Exp memory)
    {
        /*
          We are doing this as:
          getExp(mulUInt(expScale, scalar), divisor.mantissa)

          How it works:
          Exp = a / b;
          Scalar = s;
          `s / (a / b)` = `b * s / a` and since for an Exp `a = mantissa, b = expScale`
        */
        (MathError err0, uint256 numerator) = mulUInt(expScale, scalar);
        if (err0 != MathError.NO_ERROR) {
            return (err0, Exp({mantissa: 0}));
        }
        return getExp(numerator, divisor.mantissa);
    }

    /**
     * @dev Divide a scalar by an Exp, then truncate to return an unsigned integer.
     */
    function divScalarByExpTruncate(uint256 scalar, Exp memory divisor)
        internal
        pure
        returns (MathError, uint256)
    {
        (MathError err, Exp memory fraction) = divScalarByExp(scalar, divisor);
        if (err != MathError.NO_ERROR) {
            return (err, 0);
        }

        return (MathError.NO_ERROR, truncate(fraction));
    }

    /**
     * @dev Divide a scalar by an Exp, returning a new Exp.
     */
    function div_ScalarByExp(uint256 scalar, Exp memory divisor)
        internal
        pure
        returns (Exp memory)
    {
        /*
          We are doing this as:
          getExp(mulUInt(expScale, scalar), divisor.mantissa)

          How it works:
          Exp = a / b;
          Scalar = s;
          `s / (a / b)` = `b * s / a` and since for an Exp `a = mantissa, b = expScale`
        */
        uint256 numerator = mul_(expScale, scalar);
        return Exp({mantissa: div_(numerator, divisor)});
    }

    /**
     * @dev Divide a scalar by an Exp, then truncate to return an unsigned integer.
     */
    function div_ScalarByExpTruncate(uint256 scalar, Exp memory divisor)
        internal
        pure
        returns (uint256)
    {
        Exp memory fraction = div_ScalarByExp(scalar, divisor);
        return truncate(fraction);
    }

    /**
     * @dev Multiplies two exponentials, returning a new exponential.
     */
    function mulExp(Exp memory a, Exp memory b)
        internal
        pure
        returns (MathError, Exp memory)
    {
        (MathError err0, uint256 doubleScaledProduct) = mulUInt(
            a.mantissa,
            b.mantissa
        );
        if (err0 != MathError.NO_ERROR) {
            return (err0, Exp({mantissa: 0}));
        }

        // We add half the scale before dividing so that we get rounding instead of truncation.
        //  See "Listing 6" and text above it at https://accu.org/index.php/journals/1717
        // Without this change, a result like 6.6...e-19 will be truncated to 0 instead of being rounded to 1e-18.
        (MathError err1, uint256 doubleScaledProductWithHalfScale) = addUInt(
            halfExpScale,
            doubleScaledProduct
        );
        if (err1 != MathError.NO_ERROR) {
            return (err1, Exp({mantissa: 0}));
        }

        (MathError err2, uint256 product) = divUInt(
            doubleScaledProductWithHalfScale,
            expScale
        );
        // The only error `div` can return is MathError.DIVISION_BY_ZERO but we control `expScale` and it is not zero.
        assert(err2 == MathError.NO_ERROR);

        return (MathError.NO_ERROR, Exp({mantissa: product}));
    }

    /**
     * @dev Multiplies two exponentials given their mantissas, returning a new exponential.
     */
    function mulExp(uint256 a, uint256 b)
        internal
        pure
        returns (MathError, Exp memory)
    {
        return mulExp(Exp({mantissa: a}), Exp({mantissa: b}));
    }

    /**
     * @dev Multiplies three exponentials, returning a new exponential.
     */
    function mulExp3(
        Exp memory a,
        Exp memory b,
        Exp memory c
    ) internal pure returns (MathError, Exp memory) {
        (MathError err, Exp memory ab) = mulExp(a, b);
        if (err != MathError.NO_ERROR) {
            return (err, ab);
        }
        return mulExp(ab, c);
    }

    /**
     * @dev Divides two exponentials, returning a new exponential.
     *     (a/scale) / (b/scale) = (a/scale) * (scale/b) = a/b,
     *  which we can scale as an Exp by calling getExp(a.mantissa, b.mantissa)
     */
    function divExp(Exp memory a, Exp memory b)
        internal
        pure
        returns (MathError, Exp memory)
    {
        return getExp(a.mantissa, b.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 (uint256) {
        // Note: We are not using careful math here as we're performing a division that cannot fail
        return exp.mantissa / expScale;
    }

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

    function safe224(uint256 n, string memory errorMessage)
        internal
        pure
        returns (uint224)
    {
        require(n < 2**224, errorMessage);
        return uint224(n);
    }

    function safe32(uint256 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_(uint256 a, uint256 b) internal pure returns (uint256) {
        return add_(a, b, "addition overflow");
    }

    function add_(
        uint256 a,
        uint256 b,
        string memory errorMessage
    ) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a, errorMessage);
        return c;
    }

    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_(uint256 a, uint256 b) internal pure returns (uint256) {
        return sub_(a, b, "subtraction underflow");
    }

    function sub_(
        uint256 a,
        uint256 b,
        string memory errorMessage
    ) internal pure returns (uint256) {
        require(b <= a, errorMessage);
        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, uint256 b) internal pure returns (Exp memory) {
        return Exp({mantissa: mul_(a.mantissa, b)});
    }

    function mul_(uint256 a, Exp memory b) internal pure returns (uint256) {
        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, uint256 b)
        internal
        pure
        returns (Double memory)
    {
        return Double({mantissa: mul_(a.mantissa, b)});
    }

    function mul_(uint256 a, Double memory b) internal pure returns (uint256) {
        return mul_(a, b.mantissa) / doubleScale;
    }

    function mul_(uint256 a, uint256 b) internal pure returns (uint256) {
        return mul_(a, b, "multiplication overflow");
    }

    function mul_(
        uint256 a,
        uint256 b,
        string memory errorMessage
    ) internal pure returns (uint256) {
        if (a == 0 || b == 0) {
            return 0;
        }
        uint256 c = a * b;
        require(c / a == b, errorMessage);
        return c;
    }

    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, uint256 b) internal pure returns (Exp memory) {
        return Exp({mantissa: div_(a.mantissa, b)});
    }

    function div_(uint256 a, Exp memory b) internal pure returns (uint256) {
        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, uint256 b)
        internal
        pure
        returns (Double memory)
    {
        return Double({mantissa: div_(a.mantissa, b)});
    }

    function div_(uint256 a, Double memory b) internal pure returns (uint256) {
        return div_(mul_(a, doubleScale), b.mantissa);
    }

    function div_(uint256 a, uint256 b) internal pure returns (uint256) {
        return div_(a, b, "divide by zero");
    }

    function div_(
        uint256 a,
        uint256 b,
        string memory errorMessage
    ) internal pure returns (uint256) {
        require(b > 0, errorMessage);
        return a / b;
    }

    function fraction(uint256 a, uint256 b)
        internal
        pure
        returns (Double memory)
    {
        return Double({mantissa: div_(mul_(a, doubleScale), b)});
    }

    // implementation from https://github.com/Uniswap/uniswap-lib/commit/99f3f28770640ba1bb1ff460ac7c5292fb8291a0
    // original implementation: https://github.com/abdk-consulting/abdk-libraries-solidity/blob/master/ABDKMath64x64.sol#L687
    function sqrt(uint256 x) internal pure returns (uint256) {
        if (x == 0) return 0;
        uint256 xx = x;
        uint256 r = 1;

        if (xx >= 0x100000000000000000000000000000000) {
            xx >>= 128;
            r <<= 64;
        }
        if (xx >= 0x10000000000000000) {
            xx >>= 64;
            r <<= 32;
        }
        if (xx >= 0x100000000) {
            xx >>= 32;
            r <<= 16;
        }
        if (xx >= 0x10000) {
            xx >>= 16;
            r <<= 8;
        }
        if (xx >= 0x100) {
            xx >>= 8;
            r <<= 4;
        }
        if (xx >= 0x10) {
            xx >>= 4;
            r <<= 2;
        }
        if (xx >= 0x8) {
            r <<= 1;
        }

        r = (r + x / r) >> 1;
        r = (r + x / r) >> 1;
        r = (r + x / r) >> 1;
        r = (r + x / r) >> 1;
        r = (r + x / r) >> 1;
        r = (r + x / r) >> 1;
        r = (r + x / r) >> 1; // Seven iterations should be enough
        uint256 r1 = x / r;
        return (r < r1 ? r : r1);
    }
}

// File: contracts/InterestRateModel.sol



pragma solidity 0.5.16;

/**
 * @title Blueberry's InterestRateModel Interface
 * @author Compound (Modified by Blueberry)
 */
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(
        uint256 cash,
        uint256 borrows,
        uint256 reserves
    ) external view returns (uint256);

    /**
     * @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(
        uint256 cash,
        uint256 borrows,
        uint256 reserves,
        uint256 reserveFactorMantissa
    ) external view returns (uint256);
}

// File: contracts/LiquidityMiningInterface.sol



pragma solidity 0.5.16;

contract LiquidityMiningInterface {
    function comptroller() external view returns (address);

    function updateSupplyIndex(address bToken, address[] calldata accounts)
        external;

    function updateBorrowIndex(address bToken, address[] calldata accounts)
        external;
}

// File: contracts/PriceOracle/PriceOracle.sol



pragma solidity 0.5.16;

import "../BToken.sol";

contract PriceOracle {
    /**
     * @notice Get the underlying price of a bToken asset
     * @param bToken The bToken to get the underlying price of
     * @return The underlying asset price mantissa (scaled by 1e18).
     *  Zero means the price is unavailable.
     */
    function getUnderlyingPrice(BToken bToken) external view returns (uint256);
}

// File: contracts/Unitroller.sol



pragma solidity 0.5.16;

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

/**
 * @title ComptrollerCore
 * @dev Storage for the comptroller is at this address, while execution is delegated to the `comptrollerImplementation`.
 * BTokens 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 (uint256)
    {
        if (msg.sender != admin) {
            return
                fail(
                    Error.UNAUTHORIZED,
                    FailureInfo.SET_PENDING_IMPLEMENTATION_OWNER_CHECK
                );
        }

        address oldPendingImplementation = pendingComptrollerImplementation;

        pendingComptrollerImplementation = newPendingImplementation;

        emit NewPendingImplementation(
            oldPendingImplementation,
            pendingComptrollerImplementation
        );

        return uint256(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 (uint256) {
        // 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 uint256(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 (uint256)
    {
        // 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 uint256(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 (uint256) {
        // 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 uint256(Error.NO_ERROR);
    }

    /**
     * @dev Delegates execution to an implementation contract.
     * It returns to the external caller whatever the implementation returns
     * or forwards reverts.
     */
    function() 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)
            }
        }
    }
}