// Contract: LendingPoolAddressesProvider
// Target function: function balanceOf(address _user) public view returns(uint256)
 function calculateHealthFactorFromBalancesInternal(
        uint256 collateralBalanceETH,
        uint256 borrowBalanceETH,
        uint256 totalFeesETH,
        uint256 liquidationThreshold
    ) internal pure returns (uint256) {
        if (borrowBalanceETH == 0) return uint256(-1);

        return
            (collateralBalanceETH.mul(liquidationThreshold).div(100)).wadDiv(
                borrowBalanceETH.add(totalFeesETH)
            );
    }

    /**
    * @dev returns the health factor liquidation threshold
    **/
    function getHealthFactorLiquidationThreshold() public pure returns (uint256) {
        return HEALTH_FACTOR_LIQUIDATION_THRESHOLD;
    }

    /**
    * @dev accessory functions to fetch data from the lendingPoolCore
    **/
    function getReserveConfigurationData(address _reserve)
        external
        view
        returns (
            uint256 ltv,
            uint256 liquidationThreshold,
            uint256 liquidationBonus,
            address rateStrategyAddress,
            bool usageAsCollateralEnabled,
            bool borrowingEnabled,
            bool stableBorrowRateEnabled,
            bool isActive
        )
    {
        (, ltv, liquidationThreshold, usageAsCollateralEnabled) = core.getReserveConfiguration(
            _reserve
        );
        stableBorrowRateEnabled = core.getReserveIsStableBorrowRateEnabled(_reserve);
        borrowingEnabled = core.isReserveBorrowingEnabled(_reserve);
        isActive = core.getReserveIsActive(_reserve);
        liquidationBonus = core.getReserveLiquidationBonus(_reserve);

        rateStrategyAddress = core.getReserveInterestRateStrategyAddress(_reserve);
    }

    function getReserveData(address _reserve)
        external
        view
        returns (
            uint256 totalLiquidity,
            uint256 availableLiquidity,
            uint256 totalBorrowsStable,
            uint256 totalBorrowsVariable,
            uint256 liquidityRate,
            uint256 variableBorrowRate,
            uint256 stableBorrowRate,
            uint256 averageStableBorrowRate,
            uint256 utilizationRate,
            uint256 liquidityIndex,
            uint256 variableBorrowIndex,
            address aTokenAddress,
            uint40 lastUpdateTimestamp
        )
    {
        totalLiquidity = core.getReserveTotalLiquidity(_reserve);
        availableLiquidity = core.getReserveAvailableLiquidity(_reserve);
        totalBorrowsStable = core.getReserveTotalBorrowsStable(_reserve);
        totalBorrowsVariable = core.getReserveTotalBorrowsVariable(_reserve);
        liquidityRate = core.getReserveCurrentLiquidityRate(_reserve);
        variableBorrowRate = core.getReserveCurrentVariableBorrowRate(_reserve);
        stableBorrowRate = core.getReserveCurrentStableBorrowRate(_reserve);
        averageStableBorrowRate = core.getReserveCurrentAverageStableBorrowRate(_reserve);
        utilizationRate = core.getReserveUtilizationRate(_reserve);
        liquidityIndex = core.getReserveLiquidityCumulativeIndex(_reserve);
        variableBorrowIndex = core.getReserveVariableBorrowsCumulativeIndex(_reserve);
        aTokenAddress = core.getReserveATokenAddress(_reserve);
        lastUpdateTimestamp = core.getReserveLastUpdate(_reserve);
    }

    function getUserAccountData(address _user)
        external
        view
        returns (
            uint256 totalLiquidityETH,
            uint256 totalCollateralETH,
            uint256 totalBorrowsETH,
            uint256 totalFeesETH,
            uint256 availableBorrowsETH,
            uint256 currentLiquidationThreshold,
            uint256 ltv,
            uint256 healthFactor
        )
    {
        (
            totalLiquidityETH,
            totalCollateralETH,
            totalBorrowsETH,
            totalFeesETH,
            ltv,
            currentLiquidationThreshold,
            healthFactor,

        ) = calculateUserGlobalData(_user);

        availableBorrowsETH = calculateAvailableBorrowsETHInternal(
            totalCollateralETH,
            totalBorrowsETH,
            totalFeesETH,
            ltv
        );
    }

    function getUserReserveData(address _reserve, address _user)
        external
        view
        returns (
            uint256 currentATokenBalance,
            uint256 currentBorrowBalance,
            uint256 principalBorrowBalance,
            uint256 borrowRateMode,
            uint256 borrowRate,
            uint256 liquidityRate,
            uint256 originationFee,
            uint256 variableBorrowIndex,
            uint256 lastUpdateTimestamp,
            bool usageAsCollateralEnabled
        )
    {
        currentATokenBalance = AToken(core.getReserveATokenAddress(_reserve)).balanceOf(_user);
        CoreLibrary.InterestRateMode mode = core.getUserCurrentBorrowRateMode(_reserve, _user);
        (principalBorrowBalance, currentBorrowBalance, ) = core.getUserBorrowBalances(
            _reserve,
            _user
        );

        //default is 0, if mode == CoreLibrary.InterestRateMode.NONE
        if (mode == CoreLibrary.InterestRateMode.STABLE) {
            borrowRate = core.getUserCurrentStableBorrowRate(_reserve, _user);
        } else if (mode == CoreLibrary.InterestRateMode.VARIABLE) {
            borrowRate = core.getReserveCurrentVariableBorrowRate(_reserve);
        }

        borrowRateMode = uint256(mode);
        liquidityRate = core.getReserveCurrentLiquidityRate(_reserve);
        originationFee = core.getUserOriginationFee(_reserve, _user);
        variableBorrowIndex = core.getUserVariableBorrowCumulativeIndex(_reserve, _user);
        lastUpdateTimestamp = core.getUserLastUpdate(_reserve, _user);
        usageAsCollateralEnabled = core.isUserUseReserveAsCollateralEnabled(_reserve, _user);
    }
}


/**
 * @title Aave ERC20 AToken
 *
 * @dev Implementation of the interest bearing token for the DLP protocol.
 * @author Aave
 */
contract AToken is ERC20, ERC20Detailed {
    using WadRayMath for uint256;

    uint256 public constant UINT_MAX_VALUE = uint256(-1);

    /**
    * @dev emitted after the redeem action
    * @param _from the address performing the redeem
    * @param _value the amount to be redeemed
    * @param _fromBalanceIncrease the cumulated balance since the last update of the user
    * @param _fromIndex the last index of the user
    **/
    event Redeem(
        address indexed _from,
        uint256 _value,
        uint256 _fromBalanceIncrease,
        uint256 _fromIndex
    );

    /**
    * @dev emitted after the mint action
    * @param _from the address performing the mint
    * @param _value the amount to be minted
    * @param _fromBalanceIncrease the cumulated balance since the last update of the user
    * @param _fromIndex the last index of the user
    **/
    event MintOnDeposit(
        address indexed _from,
        uint256 _value,
        uint256 _fromBalanceIncrease,
        uint256 _fromIndex
    );

    /**
    * @dev emitted during the liquidation action, when the liquidator reclaims the underlying
    * asset
    * @param _from the address from which the tokens are being burned
    * @param _value the amount to be burned
    * @param _fromBalanceIncrease the cumulated balance since the last update of the user
    * @param _fromIndex the last index of the user
    **/
    event BurnOnLiquidation(
        address indexed _from,
        uint256 _value,
        uint256 _fromBalanceIncrease,
        uint256 _fromIndex
    );

    /**
    * @dev emitted during the transfer action
    * @param _from the address from which the tokens are being transferred
    * @param _to the adress of the destination
    * @param _value the amount to be minted
    * @param _fromBalanceIncrease the cumulated balance since the last update of the user
    * @param _toBalanceIncrease the cumulated balance since the last update of the destination
    * @param _fromIndex the last index of the user
    * @param _toIndex the last index of the liquidator
    **/
    event BalanceTransfer(
        address indexed _from,
        address indexed _to,
        uint256 _value,
        uint256 _fromBalanceIncrease,
        uint256 _toBalanceIncrease,
        uint256 _fromIndex,
        uint256 _toIndex
    );

    /**
    * @dev emitted when the accumulation of the interest
    * by an user is redirected to another user
    * @param _from the address from which the interest is being redirected
    * @param _to the adress of the destination
    * @param _fromBalanceIncrease the cumulated balance since the last update of the user
    * @param _fromIndex the last index of the user
    **/
    event InterestStreamRedirected(
        address indexed _from,
        address indexed _to,
        uint256 _redirectedBalance,
        uint256 _fromBalanceIncrease,
        uint256 _fromIndex
    );

    /**
    * @dev emitted when the redirected balance of an user is being updated
    * @param _targetAddress the address of which the balance is being updated
    * @param _targetBalanceIncrease the cumulated balance since the last update of the target
    * @param _targetIndex the last index of the user
    * @param _redirectedBalanceAdded the redirected balance being added
    * @param _redirectedBalanceRemoved the redirected balance being removed
    **/
    event RedirectedBalanceUpdated(
        address indexed _targetAddress,
        uint256 _targetBalanceIncrease,
        uint256 _targetIndex,
        uint256 _redirectedBalanceAdded,
        uint256 _redirectedBalanceRemoved
    );

    event InterestRedirectionAllowanceChanged(
        address indexed _from,
        address indexed _to
    );

    address public underlyingAssetAddress;

    mapping (address => uint256) private userIndexes;
    mapping (address => address) private interestRedirectionAddresses;
    mapping (address => uint256) private redirectedBalances;
    mapping (address => address) private interestRedirectionAllowances;

    LendingPoolAddressesProvider private addressesProvider;
    LendingPoolCore private core;
    LendingPool private pool;
    LendingPoolDataProvider private dataProvider;

    modifier onlyLendingPool {
        require(
            msg.sender == address(pool),
            "The caller of this function must be a lending pool"
        );
        _;
    }

    modifier whenTransferAllowed(address _from, uint256 _amount) {
        require(isTransferAllowed(_from, _amount), "Transfer cannot be allowed.");
        _;
    }

    constructor(
        LendingPoolAddressesProvider _addressesProvider,
        address _underlyingAsset,
        uint8 _underlyingAssetDecimals,
        string memory _name,
        string memory _symbol
    ) public ERC20Detailed(_name, _symbol, _underlyingAssetDecimals) {

        addressesProvider = _addressesProvider;
        core = LendingPoolCore(addressesProvider.getLendingPoolCore());
        pool = LendingPool(addressesProvider.getLendingPool());
        dataProvider = LendingPoolDataProvider(addressesProvider.getLendingPoolDataProvider());
        underlyingAssetAddress = _underlyingAsset;
    }

    /**
     * @notice ERC20 implementation internal function backing transfer() and transferFrom()
     * @dev validates the transfer before allowing it. NOTE: This is not standard ERC20 behavior
     **/
    function _transfer(address _from, address _to, uint256 _amount) internal whenTransferAllowed(_from, _amount) {

        executeTransferInternal(_from, _to, _amount);
    }


    /**
    * @dev redirects the interest generated to a target address.
    * when the interest is redirected, the user balance is added to
    * the recepient redirected balance.
    * @param _to the address to which the interest will be redirected
    **/
    function redirectInterestStream(address _to) external {
        redirectInterestStreamInternal(msg.sender, _to);
    }

    /**
    * @dev redirects the interest generated by _from to a target address.
    * when the interest is redirected, the user balance is added to
    * the recepient redirected balance. The caller needs to have allowance on
    * the interest redirection to be able to execute the function.
    * @param _from the address of the user whom interest is being redirected
    * @param _to the address to which the interest will be redirected
    **/
    function redirectInterestStreamOf(address _from, address _to) external {
        require(
            msg.sender == interestRedirectionAllowances[_from],
            "Caller is not allowed to redirect the interest of the user"
        );
        redirectInterestStreamInternal(_from,_to);
    }

    /**
    * @dev gives allowance to an address to execute the interest redirection
    * on behalf of the caller.
    * @param _to the address to which the interest will be redirected. Pass address(0) to reset
    * the allowance.
    **/
    function allowInterestRedirectionTo(address _to) external {
        require(_to != msg.sender, "User cannot give allowance to himself");
        interestRedirectionAllowances[msg.sender] = _to;
        emit InterestRedirectionAllowanceChanged(
            msg.sender,
            _to
        );
    }

    /**
    * @dev redeems aToken for the underlying asset
    * @param _amount the amount being redeemed
    **/
    function redeem(uint256 _amount) external {

        require(_amount > 0, "Amount to redeem needs to be > 0");

        //cumulates the balance of the user
        (,
        uint256 currentBalance,
        uint256 balanceIncrease,
        uint256 index) = cumulateBalanceInternal(msg.sender);

        uint256 amountToRedeem = _amount;

        //if amount is equal to uint(-1), the user wants to redeem everything
        if(_amount == UINT_MAX_VALUE){
            amountToRedeem = currentBalance;
        }

        require(amountToRedeem <= currentBalance, "User cannot redeem more than the available balance");

        //check that the user is allowed to redeem the amount
        require(isTransferAllowed(msg.sender, amountToRedeem), "Transfer cannot be allowed.");

        //if the user is redirecting his interest towards someone else,
        //we update the redirected balance of the redirection address by adding the accrued interest,
        //and removing the amount to redeem
        updateRedirectedBalanceOfRedirectionAddressInternal(msg.sender, balanceIncrease, amountToRedeem);

        // burns tokens equivalent to the amount requested
        _burn(msg.sender, amountToRedeem);

        bool userIndexReset = false;
        //reset the user data if the remaining balance is 0
        if(currentBalance.sub(amountToRedeem) == 0){
            userIndexReset = resetDataOnZeroBalanceInternal(msg.sender);
        }

        // executes redeem of the underlying asset
        pool.redeemUnderlying(
            underlyingAssetAddress,
            msg.sender,
            amountToRedeem,
            currentBalance.sub(amountToRedeem)
        );

        emit Redeem(msg.sender, amountToRedeem, balanceIncrease, userIndexReset ? 0 : index);
    }

    /**
     * @dev mints token in the event of users depositing the underlying asset into the lending pool
     * only lending pools can call this function
     * @param _account the address receiving the minted tokens
     * @param _amount the amount of tokens to mint
     */
    function mintOnDeposit(address _account, uint256 _amount) external onlyLendingPool {

        //cumulates the balance of the user
        (,
        ,
        uint256 balanceIncrease,
        uint256 index) = cumulateBalanceInternal(_account);

         //if the user is redirecting his interest towards someone else,
        //we update the redirected balance of the redirection address by adding the accrued interest
        //and the amount deposited
        updateRedirectedBalanceOfRedirectionAddressInternal(_account, balanceIncrease.add(_amount), 0);

        //mint an equivalent amount of tokens to cover the new deposit
        _mint(_account, _amount);

        emit MintOnDeposit(_account, _amount, balanceIncrease, index);
    }

    /**
     * @dev burns token in the event of a borrow being liquidated, in case the liquidators reclaims the underlying asset
     * Transfer of the liquidated asset is executed by the lending pool contract.
     * only lending pools can call this function
     * @param _account the address from which burn the aTokens
     * @param _value the amount to burn
     **/
    function burnOnLiquidation(address _account, uint256 _value) external onlyLendingPool {

        //cumulates the balance of the user being liquidated
        (,uint256 accountBalance,uint256 balanceIncrease,uint256 index) = cumulateBalanceInternal(_account);

        //adds the accrued interest and substracts the burned amount to
        //the redirected balance
        updateRedirectedBalanceOfRedirectionAddressInternal(_account, balanceIncrease, _value);

        //burns the requested amount of tokens
        _burn(_account, _value);

        bool userIndexReset = false;
        //reset the user data if the remaining balance is 0
        if(accountBalance.sub(_value) == 0){
            userIndexReset = resetDataOnZeroBalanceInternal(_account);
        }

        emit BurnOnLiquidation(_account, _value, balanceIncrease, userIndexReset ? 0 : index);
    }

    /**
     * @dev transfers tokens in the event of a borrow being liquidated, in case the liquidators reclaims the aToken
     *      only lending pools can call this function
     * @param _from the address from which transfer the aTokens
     * @param _to the destination address
     * @param _value the amount to transfer
     **/
    function transferOnLiquidation(address _from, address _to, uint256 _value) external onlyLendingPool {

        //being a normal transfer, the Transfer() and BalanceTransfer() are emitted
        //so no need to emit a specific event here
        executeTransferInternal(_from, _to, _value);
    }