Defi Lending Concepts 2

acctliquidity.sol

pragma solidity ^0.8.13;

struct AccountLiquidityLocalVars {
    uint sumCollateral;
    uint sumBorrowPlusEffects;
    uint cTokenBalance;
    uint borrowBalance;
    uint exchangeRateMantissa;
    uint oraclePriceMantissa;
    Exp collateralFactor;
    Exp exchangeRate;
    Exp oraclePrice;
    Exp tokensToDenom;
}

// ...

function getHypotheticalAccountLiquidityInternal(
    address account,
    CToken cTokenModify,
    uint redeemTokens,
    uint borrowAmount) internal view returns (Error, uint, uint) {

    AccountLiquidityLocalVars memory vars;
    uint oErr;

    CToken[] memory assets = accountAssets[account];
    for (uint i = 0; i < assets.length; i++) {
        CToken asset = assets[i];

        (oErr, vars.cTokenBalance, vars.borrowBalance, vars.exchangeRateMantissa) = asset.getAccountSnapshot(account);
        if (oErr != 0) {
            return (Error.SNAPSHOT_ERROR, 0, 0);
        }
        vars.collateralFactor = Exp({mantissa: markets[address(asset)].collateralFactorMantissa});
        vars.exchangeRate = Exp({mantissa: vars.exchangeRateMantissa});

        vars.oraclePriceMantissa = oracle.getUnderlyingPrice(asset);
        if (vars.oraclePriceMantissa == 0) {
            return (Error.PRICE_ERROR, 0, 0);
        }
        vars.oraclePrice = Exp({mantissa: vars.oraclePriceMantissa});
        vars.tokensToDenom = mul_(mul_(vars.collateralFactor, vars.exchangeRate), vars.oraclePrice);
        vars.sumCollateral = mul_ScalarTruncateAddUInt(vars.tokensToDenom, vars.cTokenBalance, vars.sumCollateral);
        vars.sumBorrowPlusEffects = mul_ScalarTruncateAddUInt(vars.oraclePrice, vars.borrowBalance, vars.sumBorrowPlusEffects);

        if (asset == cTokenModify) {
            vars.sumBorrowPlusEffects = mul_ScalarTruncateAddUInt(vars.tokensToDenom, redeemTokens, vars.sumBorrowPlusEffects);
            vars.sumBorrowPlusEffects = mul_ScalarTruncateAddUInt(vars.oraclePrice, borrowAmount, vars.sumBorrowPlusEffects);
        }
    }

    if (vars.sumCollateral > vars.sumBorrowPlusEffects) {
        return (Error.NO_ERROR, vars.sumCollateral - vars.sumBorrowPlusEffects, 0);
    } else {
        return (Error.NO_ERROR, 0, vars.sumBorrowPlusEffects - vars.sumCollateral);
    }
}