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GenericLogic.sol
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GenericLogic.sol
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// SPDX-License-Identifier: agpl-3.0
pragma solidity 0.6.12;
pragma experimental ABIEncoderV2;
import {SafeMath} from '../../../dependencies/openzeppelin/contracts/SafeMath.sol';
import {IERC20} from '../../../dependencies/openzeppelin/contracts/IERC20.sol';
import {ReserveLogic} from './ReserveLogic.sol';
import {ReserveConfiguration} from '../configuration/ReserveConfiguration.sol';
import {UserConfiguration} from '../configuration/UserConfiguration.sol';
import {WadRayMath} from '../math/WadRayMath.sol';
import {PercentageMath} from '../math/PercentageMath.sol';
import {IPriceOracleGetter} from '../../../interfaces/IPriceOracleGetter.sol';
import {DataTypes} from '../types/DataTypes.sol';
/**
* @title GenericLogic library
* @author Aave
* @title Implements protocol-level logic to calculate and validate the state of a user
*/
library GenericLogic {
using ReserveLogic for DataTypes.ReserveData;
using SafeMath for uint256;
using WadRayMath for uint256;
using PercentageMath for uint256;
using ReserveConfiguration for DataTypes.ReserveConfigurationMap;
using UserConfiguration for DataTypes.UserConfigurationMap;
uint256 public constant HEALTH_FACTOR_LIQUIDATION_THRESHOLD = 1 ether;
struct balanceDecreaseAllowedLocalVars {
uint256 decimals;
uint256 liquidationThreshold;
uint256 totalCollateralInETH;
uint256 totalDebtInETH;
uint256 avgLiquidationThreshold;
uint256 amountToDecreaseInETH;
uint256 collateralBalanceAfterDecrease;
uint256 liquidationThresholdAfterDecrease;
uint256 healthFactorAfterDecrease;
bool reserveUsageAsCollateralEnabled;
}
/**
* @dev Checks if a specific balance decrease is allowed
* (i.e. doesn't bring the user borrow position health factor under HEALTH_FACTOR_LIQUIDATION_THRESHOLD)
* @param asset The address of the underlying asset of the reserve
* @param user The address of the user
* @param amount The amount to decrease
* @param reservesData The data of all the reserves
* @param userConfig The user configuration
* @param reserves The list of all the active reserves
* @param oracle The address of the oracle contract
* @return true if the decrease of the balance is allowed
**/
function balanceDecreaseAllowed(
address asset,
address user,
uint256 amount,
mapping(address => DataTypes.ReserveData) storage reservesData,
DataTypes.UserConfigurationMap calldata userConfig,
mapping(uint256 => address) storage reserves,
uint256 reservesCount,
address oracle
) external view returns (bool) {
if (!userConfig.isBorrowingAny() || !userConfig.isUsingAsCollateral(reservesData[asset].id)) {
return true;
}
balanceDecreaseAllowedLocalVars memory vars;
(, vars.liquidationThreshold, , vars.decimals, ) = reservesData[asset]
.configuration
.getParams();
if (vars.liquidationThreshold == 0) {
return true;
}
(
vars.totalCollateralInETH,
vars.totalDebtInETH,
,
vars.avgLiquidationThreshold,
) = calculateUserAccountData(user, reservesData, userConfig, reserves, reservesCount, oracle);
if (vars.totalDebtInETH == 0) {
return true;
}
vars.amountToDecreaseInETH = IPriceOracleGetter(oracle).getAssetPrice(asset).mul(amount).div(
10**vars.decimals
);
vars.collateralBalanceAfterDecrease = vars.totalCollateralInETH.sub(vars.amountToDecreaseInETH);
//if there is a borrow, there can't be 0 collateral
if (vars.collateralBalanceAfterDecrease == 0) {
return false;
}
vars.liquidationThresholdAfterDecrease = vars
.totalCollateralInETH
.mul(vars.avgLiquidationThreshold)
.sub(vars.amountToDecreaseInETH.mul(vars.liquidationThreshold))
.div(vars.collateralBalanceAfterDecrease);
uint256 healthFactorAfterDecrease =
calculateHealthFactorFromBalances(
vars.collateralBalanceAfterDecrease,
vars.totalDebtInETH,
vars.liquidationThresholdAfterDecrease
);
return healthFactorAfterDecrease >= GenericLogic.HEALTH_FACTOR_LIQUIDATION_THRESHOLD;
}
struct CalculateUserAccountDataVars {
uint256 reserveUnitPrice;
uint256 tokenUnit;
uint256 compoundedLiquidityBalance;
uint256 compoundedBorrowBalance;
uint256 decimals;
uint256 ltv;
uint256 liquidationThreshold;
uint256 i;
uint256 healthFactor;
uint256 totalCollateralInETH;
uint256 totalDebtInETH;
uint256 avgLtv;
uint256 avgLiquidationThreshold;
uint256 reservesLength;
bool healthFactorBelowThreshold;
address currentReserveAddress;
bool usageAsCollateralEnabled;
bool userUsesReserveAsCollateral;
}
/**
* @dev Calculates the user data across the reserves.
* this includes the total liquidity/collateral/borrow balances in ETH,
* the average Loan To Value, the average Liquidation Ratio, and the Health factor.
* @param user The address of the user
* @param reservesData Data of all the reserves
* @param userConfig The configuration of the user
* @param reserves The list of the available reserves
* @param oracle The price oracle address
* @return The total collateral and total debt of the user in ETH, the avg ltv, liquidation threshold and the HF
**/
function calculateUserAccountData(
address user,
mapping(address => DataTypes.ReserveData) storage reservesData,
DataTypes.UserConfigurationMap memory userConfig,
mapping(uint256 => address) storage reserves,
uint256 reservesCount,
address oracle
)
internal
view
returns (
uint256,
uint256,
uint256,
uint256,
uint256
)
{
CalculateUserAccountDataVars memory vars;
if (userConfig.isEmpty()) {
return (0, 0, 0, 0, uint256(-1));
}
for (vars.i = 0; vars.i < reservesCount; vars.i++) {
if (!userConfig.isUsingAsCollateralOrBorrowing(vars.i)) {
continue;
}
vars.currentReserveAddress = reserves[vars.i];
DataTypes.ReserveData storage currentReserve = reservesData[vars.currentReserveAddress];
(vars.ltv, vars.liquidationThreshold, , vars.decimals, ) = currentReserve
.configuration
.getParams();
vars.tokenUnit = 10**vars.decimals;
vars.reserveUnitPrice = IPriceOracleGetter(oracle).getAssetPrice(vars.currentReserveAddress);
if (vars.liquidationThreshold != 0 && userConfig.isUsingAsCollateral(vars.i)) {
vars.compoundedLiquidityBalance = IERC20(currentReserve.aTokenAddress).balanceOf(user);
uint256 liquidityBalanceETH =
vars.reserveUnitPrice.mul(vars.compoundedLiquidityBalance).div(vars.tokenUnit);
vars.totalCollateralInETH = vars.totalCollateralInETH.add(liquidityBalanceETH);
vars.avgLtv = vars.avgLtv.add(liquidityBalanceETH.mul(vars.ltv));
vars.avgLiquidationThreshold = vars.avgLiquidationThreshold.add(
liquidityBalanceETH.mul(vars.liquidationThreshold)
);
}
if (userConfig.isBorrowing(vars.i)) {
vars.compoundedBorrowBalance = IERC20(currentReserve.stableDebtTokenAddress).balanceOf(
user
);
vars.compoundedBorrowBalance = vars.compoundedBorrowBalance.add(
IERC20(currentReserve.variableDebtTokenAddress).balanceOf(user)
);
vars.totalDebtInETH = vars.totalDebtInETH.add(
vars.reserveUnitPrice.mul(vars.compoundedBorrowBalance).div(vars.tokenUnit)
);
}
}
vars.avgLtv = vars.totalCollateralInETH > 0
? vars.avgLtv.div(vars.totalCollateralInETH)
: 0;
vars.avgLiquidationThreshold = vars.totalCollateralInETH > 0
? vars.avgLiquidationThreshold.div(vars.totalCollateralInETH)
: 0;
vars.healthFactor = calculateHealthFactorFromBalances(
vars.totalCollateralInETH,
vars.totalDebtInETH,
vars.avgLiquidationThreshold
);
return (
vars.totalCollateralInETH,
vars.totalDebtInETH,
vars.avgLtv,
vars.avgLiquidationThreshold,
vars.healthFactor
);
}
/**
* @dev Calculates the health factor from the corresponding balances
* @param totalCollateralInETH The total collateral in ETH
* @param totalDebtInETH The total debt in ETH
* @param liquidationThreshold The avg liquidation threshold
* @return The health factor calculated from the balances provided
**/
function calculateHealthFactorFromBalances(
uint256 totalCollateralInETH,
uint256 totalDebtInETH,
uint256 liquidationThreshold
) internal pure returns (uint256) {
if (totalDebtInETH == 0) return uint256(-1);
return (totalCollateralInETH.percentMul(liquidationThreshold)).wadDiv(totalDebtInETH);
}
/**
* @dev Calculates the equivalent amount in ETH that an user can borrow, depending on the available collateral and the
* average Loan To Value
* @param totalCollateralInETH The total collateral in ETH
* @param totalDebtInETH The total borrow balance
* @param ltv The average loan to value
* @return the amount available to borrow in ETH for the user
**/
function calculateAvailableBorrowsETH(
uint256 totalCollateralInETH,
uint256 totalDebtInETH,
uint256 ltv
) internal pure returns (uint256) {
uint256 availableBorrowsETH = totalCollateralInETH.percentMul(ltv);
if (availableBorrowsETH < totalDebtInETH) {
return 0;
}
availableBorrowsETH = availableBorrowsETH.sub(totalDebtInETH);
return availableBorrowsETH;
}
}