// File: contracts/Borrowable.sol



pragma solidity =0.5.16;

import "./PoolToken.sol";
import "./BAllowance.sol";
import "./BInterestRateModel.sol";
import "./BSetter.sol";
import "./BStorage.sol";
import "./interfaces/IBorrowable.sol";
import "./interfaces/ICollateral.sol";
import "./interfaces/ITarotCallee.sol";
import "./interfaces/IERC20.sol";
import "./interfaces/IFactory.sol";
import "./interfaces/IBorrowTracker.sol";
import "./libraries/Math.sol";

contract Borrowable is
    IBorrowable,
    PoolToken,
    BStorage,
    BSetter,
    BInterestRateModel,
    BAllowance
{
    uint256 public constant BORROW_FEE = 0.0001e18; //0.01%

    event Borrow(
        address indexed sender,
        address indexed borrower,
        address indexed receiver,
        uint256 borrowAmount,
        uint256 repayAmount,
        uint256 accountBorrowsPrior,
        uint256 accountBorrows,
        uint256 totalBorrows
    );
    event Liquidate(
        address indexed sender,
        address indexed borrower,
        address indexed liquidator,
        uint256 seizeTokens,
        uint256 repayAmount,
        uint256 accountBorrowsPrior,
        uint256 accountBorrows,
        uint256 totalBorrows
    );

    constructor() public {}

    /*** PoolToken ***/

    function _update() internal {
        super._update();
        _calculateBorrowRate();
    }

    function _mintReserves(uint256 _exchangeRate, uint256 _totalSupply)
        internal
        returns (uint256)
    {
        uint256 _exchangeRateLast = exchangeRateLast;
        if (_exchangeRate > _exchangeRateLast) {
            uint256 _exchangeRateNew =
                _exchangeRate.sub(
                    _exchangeRate.sub(_exchangeRateLast).mul(reserveFactor).div(
                        1e18
                    )
                );
            uint256 liquidity =
                _totalSupply.mul(_exchangeRate).div(_exchangeRateNew).sub(
                    _totalSupply
                );
            if (liquidity > 0) {
                address reservesManager = IFactory(factory).reservesManager();
                _mint(reservesManager, liquidity);
            }
            exchangeRateLast = _exchangeRateNew;
            return _exchangeRateNew;
        } else return _exchangeRate;
    }

    function exchangeRate() public accrue returns (uint256) {
        uint256 _totalSupply = totalSupply;
        uint256 _actualBalance = totalBalance.add(totalBorrows);
        if (_totalSupply == 0 || _actualBalance == 0)
            return initialExchangeRate;
        uint256 _exchangeRate = _actualBalance.mul(1e18).div(_totalSupply);
        return _mintReserves(_exchangeRate, _totalSupply);
    }

    // force totalBalance to match real balance
    function sync() external nonReentrant update accrue {}

    /*** Borrowable ***/

    // this is the stored borrow balance; the current borrow balance may be slightly higher
    function borrowBalance(address borrower) public view returns (uint256) {
        BorrowSnapshot memory borrowSnapshot = borrowBalances[borrower];
        if (borrowSnapshot.interestIndex == 0) return 0; // not initialized
        return
            uint256(borrowSnapshot.principal).mul(borrowIndex).div(
                borrowSnapshot.interestIndex
            );
    }

    function _trackBorrow(
        address borrower,
        uint256 accountBorrows,
        uint256 _borrowIndex
    ) internal {
        address _borrowTracker = borrowTracker;
        if (_borrowTracker == address(0)) return;
        IBorrowTracker(_borrowTracker).trackBorrow(
            borrower,
            accountBorrows,
            _borrowIndex
        );
    }

    function _updateBorrow(
        address borrower,
        uint256 borrowAmount,
        uint256 repayAmount
    )
        private
        returns (
            uint256 accountBorrowsPrior,
            uint256 accountBorrows,
            uint256 _totalBorrows
        )
    {
        accountBorrowsPrior = borrowBalance(borrower);
        if (borrowAmount == repayAmount)
            return (accountBorrowsPrior, accountBorrowsPrior, totalBorrows);
        uint112 _borrowIndex = borrowIndex;
        if (borrowAmount > repayAmount) {
            BorrowSnapshot storage borrowSnapshot = borrowBalances[borrower];
            uint256 increaseAmount = borrowAmount - repayAmount;
            accountBorrows = accountBorrowsPrior.add(increaseAmount);
            borrowSnapshot.principal = safe112(accountBorrows);
            borrowSnapshot.interestIndex = _borrowIndex;
            _totalBorrows = uint256(totalBorrows).add(increaseAmount);
            totalBorrows = safe112(_totalBorrows);
        } else {
            BorrowSnapshot storage borrowSnapshot = borrowBalances[borrower];
            uint256 decreaseAmount = repayAmount - borrowAmount;
            accountBorrows = accountBorrowsPrior > decreaseAmount
                ? accountBorrowsPrior - decreaseAmount
                : 0;
            borrowSnapshot.principal = safe112(accountBorrows);
            if (accountBorrows == 0) {
                borrowSnapshot.interestIndex = 0;
            } else {
                borrowSnapshot.interestIndex = _borrowIndex;
            }
            uint256 actualDecreaseAmount =
                accountBorrowsPrior.sub(accountBorrows);
            _totalBorrows = totalBorrows; // gas savings
            _totalBorrows = _totalBorrows > actualDecreaseAmount
                ? _totalBorrows - actualDecreaseAmount
                : 0;
            totalBorrows = safe112(_totalBorrows);
        }
        _trackBorrow(borrower, accountBorrows, _borrowIndex);
    }

    // this low-level function should be called from another contract
    function borrow(
        address borrower,
        address receiver,
        uint256 borrowAmount,
        bytes calldata data
    ) external nonReentrant update accrue {
        uint256 _totalBalance = totalBalance;
        require(borrowAmount <= _totalBalance, "Tarot: INSUFFICIENT_CASH");
        _checkBorrowAllowance(borrower, msg.sender, borrowAmount);

        // optimistically transfer funds
        if (borrowAmount > 0) _safeTransfer(receiver, borrowAmount);
        if (data.length > 0)
            ITarotCallee(receiver).tarotBorrow(
                msg.sender,
                borrower,
                borrowAmount,
                data
            );
        uint256 balance = IERC20(underlying).balanceOf(address(this));

        uint256 borrowFee = borrowAmount.mul(BORROW_FEE).div(1e18);
        uint256 adjustedBorrowAmount = borrowAmount.add(borrowFee);
        uint256 repayAmount = balance.add(borrowAmount).sub(_totalBalance);
        (
            uint256 accountBorrowsPrior,
            uint256 accountBorrows,
            uint256 _totalBorrows
        ) = _updateBorrow(borrower, adjustedBorrowAmount, repayAmount);

        if (adjustedBorrowAmount > repayAmount)
            require(
                ICollateral(collateral).canBorrow(
                    borrower,
                    address(this),
                    accountBorrows
                ),
                "Tarot: INSUFFICIENT_LIQUIDITY"
            );

        emit Borrow(
            msg.sender,
            borrower,
            receiver,
            borrowAmount,
            repayAmount,
            accountBorrowsPrior,
            accountBorrows,
            _totalBorrows
        );
    }

    // this low-level function should be called from another contract
    function liquidate(address borrower, address liquidator)
        external
        nonReentrant
        update
        accrue
        returns (uint256 seizeTokens)
    {
        uint256 balance = IERC20(underlying).balanceOf(address(this));
        uint256 repayAmount = balance.sub(totalBalance);

        uint256 actualRepayAmount =
            Math.min(borrowBalance(borrower), repayAmount);
        seizeTokens = ICollateral(collateral).seize(
            liquidator,
            borrower,
            actualRepayAmount
        );
        (
            uint256 accountBorrowsPrior,
            uint256 accountBorrows,
            uint256 _totalBorrows
        ) = _updateBorrow(borrower, 0, repayAmount);

        emit Liquidate(
            msg.sender,
            borrower,
            liquidator,
            seizeTokens,
            repayAmount,
            accountBorrowsPrior,
            accountBorrows,
            _totalBorrows
        );
    }

    function trackBorrow(address borrower) external {
        _trackBorrow(borrower, borrowBalance(borrower), borrowIndex);
    }

    modifier accrue() {
        accrueInterest();
        _;
    }
}

// File: contracts/PoolToken.sol



pragma solidity =0.5.16;

import "./TarotERC20.sol";
import "./interfaces/IERC20.sol";
import "./interfaces/IPoolToken.sol";
import "./libraries/SafeMath.sol";

contract PoolToken is IPoolToken, TarotERC20 {
    uint256 internal constant initialExchangeRate = 1e18;
    address public underlying;
    address public factory;
    uint256 public totalBalance;
    uint256 public constant MINIMUM_LIQUIDITY = 1000;

    event Mint(
        address indexed sender,
        address indexed minter,
        uint256 mintAmount,
        uint256 mintTokens
    );
    event Redeem(
        address indexed sender,
        address indexed redeemer,
        uint256 redeemAmount,
        uint256 redeemTokens
    );
    event Sync(uint256 totalBalance);

    /*** Initialize ***/

    // called once by the factory
    function _setFactory() external {
        require(factory == address(0), "Tarot: FACTORY_ALREADY_SET");
        factory = msg.sender;
    }

    /*** PoolToken ***/

    function _update() internal {
        totalBalance = IERC20(underlying).balanceOf(address(this));
        emit Sync(totalBalance);
    }

    function exchangeRate() public returns (uint256) {
        uint256 _totalSupply = totalSupply; // gas savings
        uint256 _totalBalance = totalBalance; // gas savings
        if (_totalSupply == 0 || _totalBalance == 0) return initialExchangeRate;
        return _totalBalance.mul(1e18).div(_totalSupply);
    }

    // this low-level function should be called from another contract
    function mint(address minter)
        external
        nonReentrant
        update
        returns (uint256 mintTokens)
    {
        uint256 balance = IERC20(underlying).balanceOf(address(this));
        uint256 mintAmount = balance.sub(totalBalance);
        mintTokens = mintAmount.mul(1e18).div(exchangeRate());

        if (totalSupply == 0) {
            // permanently lock the first MINIMUM_LIQUIDITY tokens
            mintTokens = mintTokens.sub(MINIMUM_LIQUIDITY);
            _mint(address(0), MINIMUM_LIQUIDITY);
        }
        require(mintTokens > 0, "Tarot: MINT_AMOUNT_ZERO");
        _mint(minter, mintTokens);
        emit Mint(msg.sender, minter, mintAmount, mintTokens);
    }

    // this low-level function should be called from another contract
    function redeem(address redeemer)
        external
        nonReentrant
        update
        returns (uint256 redeemAmount)
    {
        uint256 redeemTokens = balanceOf[address(this)];
        redeemAmount = redeemTokens.mul(exchangeRate()).div(1e18);

        require(redeemAmount > 0, "Tarot: REDEEM_AMOUNT_ZERO");
        require(redeemAmount <= totalBalance, "Tarot: INSUFFICIENT_CASH");
        _burn(address(this), redeemTokens);
        _safeTransfer(redeemer, redeemAmount);
        emit Redeem(msg.sender, redeemer, redeemAmount, redeemTokens);
    }

    // force real balance to match totalBalance
    function skim(address to) external nonReentrant {
        _safeTransfer(
            to,
            IERC20(underlying).balanceOf(address(this)).sub(totalBalance)
        );
    }

    // force totalBalance to match real balance
    function sync() external nonReentrant update {}

    /*** Utilities ***/

    // same safe transfer function used by UniSwapV2 (with fixed underlying)
    bytes4 private constant SELECTOR =
        bytes4(keccak256(bytes("transfer(address,uint256)")));

    function _safeTransfer(address to, uint256 amount) internal {
        (bool success, bytes memory data) =
            underlying.call(abi.encodeWithSelector(SELECTOR, to, amount));
        require(
            success && (data.length == 0 || abi.decode(data, (bool))),
            "Tarot: TRANSFER_FAILED"
        );
    }

    // prevents a contract from calling itself, directly or indirectly.
    bool internal _notEntered = true;
    modifier nonReentrant() {
        require(_notEntered, "Tarot: REENTERED");
        _notEntered = false;
        _;
        _notEntered = true;
    }

    // update totalBalance with current balance
    modifier update() {
        _;
        _update();
    }
}

// File: contracts/BAllowance.sol



pragma solidity =0.5.16;

import "./BStorage.sol";
import "./PoolToken.sol";

contract BAllowance is PoolToken, BStorage {
    event BorrowApproval(
        address indexed owner,
        address indexed spender,
        uint256 value
    );

    function _borrowApprove(
        address owner,
        address spender,
        uint256 value
    ) private {
        borrowAllowance[owner][spender] = value;
        emit BorrowApproval(owner, spender, value);
    }

    function borrowApprove(address spender, uint256 value)
        external
        returns (bool)
    {
        _borrowApprove(msg.sender, spender, value);
        return true;
    }

    function _checkBorrowAllowance(
        address owner,
        address spender,
        uint256 value
    ) internal {
        uint256 _borrowAllowance = borrowAllowance[owner][spender];
        if (spender != owner && _borrowAllowance != uint256(-1)) {
            require(_borrowAllowance >= value, "Tarot: BORROW_NOT_ALLOWED");
            borrowAllowance[owner][spender] = _borrowAllowance - value;
        }
    }

    // keccak256("BorrowPermit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)");
    bytes32 public constant BORROW_PERMIT_TYPEHASH =
        0xf6d86ed606f871fa1a557ac0ba607adce07767acf53f492fb215a1a4db4aea6f;

    function borrowPermit(
        address owner,
        address spender,
        uint256 value,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external {
        _checkSignature(
            owner,
            spender,
            value,
            deadline,
            v,
            r,
            s,
            BORROW_PERMIT_TYPEHASH
        );
        _borrowApprove(owner, spender, value);
    }
}

// File: contracts/BInterestRateModel.sol



pragma solidity =0.5.16;

import "./BStorage.sol";
import "./PoolToken.sol";

contract BInterestRateModel is PoolToken, BStorage {

	// When utilization is 100% borrowRate is kinkBorrowRate * KINK_MULTIPLIER
	// kinkBorrowRate relative adjustment per second belongs to [1-adjustSpeed, 1+adjustSpeed*(KINK_MULTIPLIER-1)]
	uint public constant KINK_MULTIPLIER = 3;
	uint public constant KINK_BORROW_RATE_MAX = 110.350076e9; //348% per year
	uint public constant KINK_BORROW_RATE_MIN = 0.31709792e9; //1% per year

	event AccrueInterest(uint interestAccumulated, uint borrowIndex, uint totalBorrows);
	event CalculateKinkBorrowRate(uint kinkBorrowRate);
	event CalculateBorrowRate(uint borrowRate);
		
	function _calculateBorrowRate() internal {
		uint _kinkUtilizationRate = kinkUtilizationRate;		
		uint _adjustSpeed = adjustSpeed;
		uint _borrowRate = borrowRate;	
		uint _kinkBorrowRate = kinkBorrowRate;
		uint32 _rateUpdateTimestamp = rateUpdateTimestamp;		
	
		// update kinkBorrowRate using previous borrowRate
		uint32 timeElapsed = getBlockTimestamp() - _rateUpdateTimestamp; // underflow is desired
		if(timeElapsed > 0) {
			rateUpdateTimestamp = getBlockTimestamp();
			uint adjustFactor;
			
			if (_borrowRate < _kinkBorrowRate) {
				// never overflows, _kinkBorrowRate is never 0
				uint tmp = (_kinkBorrowRate - _borrowRate) * 1e18 / _kinkBorrowRate * _adjustSpeed * timeElapsed / 1e18;
				adjustFactor = tmp > 1e18 ? 0 : 1e18 - tmp;
			} else {
				// never overflows, _kinkBorrowRate is never 0
				uint tmp = (_borrowRate - _kinkBorrowRate) * 1e18 / _kinkBorrowRate * _adjustSpeed * timeElapsed / 1e18;
				adjustFactor = tmp + 1e18;
			}
			
			// never overflows
			_kinkBorrowRate = _kinkBorrowRate * adjustFactor / 1e18;
			if(_kinkBorrowRate > KINK_BORROW_RATE_MAX) _kinkBorrowRate = KINK_BORROW_RATE_MAX;
			if(_kinkBorrowRate < KINK_BORROW_RATE_MIN) _kinkBorrowRate = KINK_BORROW_RATE_MIN;

			kinkBorrowRate = uint48(_kinkBorrowRate);
			emit CalculateKinkBorrowRate(_kinkBorrowRate);
		}
		
		uint _utilizationRate;
		{ // avoid stack to deep
		uint _totalBorrows = totalBorrows; // gas savings
		uint _actualBalance = totalBalance.add(_totalBorrows);
		_utilizationRate = (_actualBalance == 0) ? 0 : _totalBorrows * 1e18 / _actualBalance;
		}
		
		// update borrowRate using the new kinkBorrowRate	
		if(_utilizationRate <= _kinkUtilizationRate) {
			// never overflows, _kinkUtilizationRate is never 0
			_borrowRate = _kinkBorrowRate * _utilizationRate / _kinkUtilizationRate;
		} else {
			// never overflows, _kinkUtilizationRate is always < 1e18
			uint overUtilization = (_utilizationRate - _kinkUtilizationRate) * 1e18 / (1e18 - _kinkUtilizationRate);
			// never overflows
			_borrowRate = ((KINK_MULTIPLIER - 1) * overUtilization + 1e18) * _kinkBorrowRate / 1e18;
		}
		borrowRate = uint48(_borrowRate);
		emit CalculateBorrowRate(_borrowRate);
	}
	
	// applies accrued interest to total borrows and reserves
	function accrueInterest() public {
		uint _borrowIndex = borrowIndex;
		uint _totalBorrows = totalBorrows;
		uint32 _accrualTimestamp = accrualTimestamp;
		
		uint32 blockTimestamp = getBlockTimestamp();
		if (_accrualTimestamp == blockTimestamp) return;
		uint32 timeElapsed = blockTimestamp - _accrualTimestamp; // underflow is desired
		accrualTimestamp = blockTimestamp;
		
		uint interestFactor = uint(borrowRate).mul(timeElapsed);	
		uint interestAccumulated = interestFactor.mul(_totalBorrows).div(1e18);
		_totalBorrows = _totalBorrows.add( interestAccumulated );
		_borrowIndex = _borrowIndex.add( interestFactor.mul(_borrowIndex).div(1e18) );
	
		borrowIndex = safe112(_borrowIndex);
		totalBorrows = safe112(_totalBorrows);
		emit AccrueInterest(interestAccumulated, _borrowIndex, _totalBorrows);
	}
		
	function getBlockTimestamp() public view returns (uint32) {
		return uint32(block.timestamp % 2**32);
	}
}
// File: contracts/BSetter.sol



pragma solidity =0.5.16;

import "./BStorage.sol";
import "./PoolToken.sol";
import "./interfaces/IFactory.sol";

contract BSetter is PoolToken, BStorage {
    uint256 public constant RESERVE_FACTOR_MAX = 0.20e18; //20%
    uint256 public constant KINK_UR_MIN = 0.50e18; //50%
    uint256 public constant KINK_UR_MAX = 0.99e18; //99%
    uint256 public constant ADJUST_SPEED_MIN = 0.05787037e12; //0.5% per day
    uint256 public constant ADJUST_SPEED_MAX = 115.74074e12; //1000% per day

    event NewReserveFactor(uint256 newReserveFactor);
    event NewKinkUtilizationRate(uint256 newKinkUtilizationRate);
    event NewAdjustSpeed(uint256 newAdjustSpeed);
    event NewBorrowTracker(address newBorrowTracker);

    // called once by the factory at time of deployment
    function _initialize(
        string calldata _name,
        string calldata _symbol,
        address _underlying,
        address _collateral
    ) external {
        require(msg.sender == factory, "Tarot: UNAUTHORIZED"); // sufficient check
        _setName(_name, _symbol);
        underlying = _underlying;
        collateral = _collateral;
        exchangeRateLast = initialExchangeRate;
    }

    function _setReserveFactor(uint256 newReserveFactor) external nonReentrant {
        _checkSetting(newReserveFactor, 0, RESERVE_FACTOR_MAX);
        reserveFactor = newReserveFactor;
        emit NewReserveFactor(newReserveFactor);
    }

    function _setKinkUtilizationRate(uint256 newKinkUtilizationRate)
        external
        nonReentrant
    {
        _checkSetting(newKinkUtilizationRate, KINK_UR_MIN, KINK_UR_MAX);
        kinkUtilizationRate = newKinkUtilizationRate;
        emit NewKinkUtilizationRate(newKinkUtilizationRate);
    }

    function _setAdjustSpeed(uint256 newAdjustSpeed) external nonReentrant {
        _checkSetting(newAdjustSpeed, ADJUST_SPEED_MIN, ADJUST_SPEED_MAX);
        adjustSpeed = newAdjustSpeed;
        emit NewAdjustSpeed(newAdjustSpeed);
    }

    function _setBorrowTracker(address newBorrowTracker) external nonReentrant {
        _checkAdmin();
        borrowTracker = newBorrowTracker;
        emit NewBorrowTracker(newBorrowTracker);
    }

    function _checkSetting(
        uint256 parameter,
        uint256 min,
        uint256 max
    ) internal view {
        _checkAdmin();
        require(parameter >= min, "Tarot: INVALID_SETTING");
        require(parameter <= max, "Tarot: INVALID_SETTING");
    }

    function _checkAdmin() internal view {
        require(msg.sender == IFactory(factory).admin(), "Tarot: UNAUTHORIZED");
    }
}

// File: contracts/BStorage.sol



pragma solidity =0.5.16;

contract BStorage {
    address public collateral;

    mapping(address => mapping(address => uint256)) public borrowAllowance;

    struct BorrowSnapshot {
        uint112 principal; // amount in underlying when the borrow was last updated
        uint112 interestIndex; // borrow index when borrow was last updated
    }
    mapping(address => BorrowSnapshot) internal borrowBalances;

    // use one memory slot
    uint112 public borrowIndex = 1e18;
    uint112 public totalBorrows;
    uint32 public accrualTimestamp = uint32(block.timestamp % 2**32);

    uint256 public exchangeRateLast;

    // use one memory slot
    uint48 public borrowRate;
    uint48 public kinkBorrowRate = 6.3419584e9; //20% per year
    uint32 public rateUpdateTimestamp = uint32(block.timestamp % 2**32);

    uint256 public reserveFactor = 0.10e18; //10%
    uint256 public kinkUtilizationRate = 0.75e18; //75%
    uint256 public adjustSpeed = 50e12; //432% per day
    address public borrowTracker;

    function safe112(uint256 n) internal pure returns (uint112) {
        require(n < 2**112, "Tarot: SAFE112");
        return uint112(n);
    }
}

// File: contracts/interfaces/IBorrowable.sol



pragma solidity >=0.5.0;

interface IBorrowable {
    /*** Tarot ERC20 ***/

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

    function name() external pure returns (string memory);

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

    function decimals() external pure returns (uint8);

    function totalSupply() external view returns (uint256);

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

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

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

    function transfer(address to, uint256 value) external returns (bool);

    function transferFrom(
        address from,
        address to,
        uint256 value
    ) external returns (bool);

    function DOMAIN_SEPARATOR() external view returns (bytes32);

    function PERMIT_TYPEHASH() external pure returns (bytes32);

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

    function permit(
        address owner,
        address spender,
        uint256 value,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external;

    /*** Pool Token ***/

    event Mint(
        address indexed sender,
        address indexed minter,
        uint256 mintAmount,
        uint256 mintTokens
    );
    event Redeem(
        address indexed sender,
        address indexed redeemer,
        uint256 redeemAmount,
        uint256 redeemTokens
    );
    event Sync(uint256 totalBalance);

    function underlying() external view returns (address);

    function factory() external view returns (address);

    function totalBalance() external view returns (uint256);

    function MINIMUM_LIQUIDITY() external pure returns (uint256);

    function exchangeRate() external returns (uint256);

    function mint(address minter) external returns (uint256 mintTokens);

    function redeem(address redeemer) external returns (uint256 redeemAmount);

    function skim(address to) external;

    function sync() external;

    function _setFactory() external;

    /*** Borrowable ***/

    event BorrowApproval(
        address indexed owner,
        address indexed spender,
        uint256 value
    );
    event Borrow(
        address indexed sender,
        address indexed borrower,
        address indexed receiver,
        uint256 borrowAmount,
        uint256 repayAmount,
        uint256 accountBorrowsPrior,
        uint256 accountBorrows,
        uint256 totalBorrows
    );
    event Liquidate(
        address indexed sender,
        address indexed borrower,
        address indexed liquidator,
        uint256 seizeTokens,
        uint256 repayAmount,
        uint256 accountBorrowsPrior,
        uint256 accountBorrows,
        uint256 totalBorrows
    );

    function BORROW_FEE() external pure returns (uint256);

    function collateral() external view returns (address);

    function reserveFactor() external view returns (uint256);

    function exchangeRateLast() external view returns (uint256);

    function borrowIndex() external view returns (uint256);

    function totalBorrows() external view returns (uint256);

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

    function borrowBalance(address borrower) external view returns (uint256);

    function borrowTracker() external view returns (address);

    function BORROW_PERMIT_TYPEHASH() external pure returns (bytes32);

    function borrowApprove(address spender, uint256 value)
        external
        returns (bool);

    function borrowPermit(
        address owner,
        address spender,
        uint256 value,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external;

    function borrow(
        address borrower,
        address receiver,
        uint256 borrowAmount,
        bytes calldata data
    ) external;

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

    function trackBorrow(address borrower) external;

    /*** Borrowable Interest Rate Model ***/

    event AccrueInterest(
        uint256 interestAccumulated,
        uint256 borrowIndex,
        uint256 totalBorrows
    );
    event CalculateKink(uint256 kinkRate);
    event CalculateBorrowRate(uint256 borrowRate);

    function KINK_BORROW_RATE_MAX() external pure returns (uint256);

    function KINK_BORROW_RATE_MIN() external pure returns (uint256);

    function KINK_MULTIPLIER() external pure returns (uint256);

    function borrowRate() external view returns (uint256);

    function kinkBorrowRate() external view returns (uint256);

    function kinkUtilizationRate() external view returns (uint256);

    function adjustSpeed() external view returns (uint256);

    function rateUpdateTimestamp() external view returns (uint32);

    function accrualTimestamp() external view returns (uint32);

    function accrueInterest() external;

    /*** Borrowable Setter ***/

    event NewReserveFactor(uint256 newReserveFactor);
    event NewKinkUtilizationRate(uint256 newKinkUtilizationRate);
    event NewAdjustSpeed(uint256 newAdjustSpeed);
    event NewBorrowTracker(address newBorrowTracker);

    function RESERVE_FACTOR_MAX() external pure returns (uint256);

    function KINK_UR_MIN() external pure returns (uint256);

    function KINK_UR_MAX() external pure returns (uint256);

    function ADJUST_SPEED_MIN() external pure returns (uint256);

    function ADJUST_SPEED_MAX() external pure returns (uint256);

    function _initialize(
        string calldata _name,
        string calldata _symbol,
        address _underlying,
        address _collateral
    ) external;

    function _setReserveFactor(uint256 newReserveFactor) external;

    function _setKinkUtilizationRate(uint256 newKinkUtilizationRate) external;

    function _setAdjustSpeed(uint256 newAdjustSpeed) external;

    function _setBorrowTracker(address newBorrowTracker) external;
}

// File: contracts/interfaces/ICollateral.sol



pragma solidity >=0.5.0;

interface ICollateral {
    /*** Tarot ERC20 ***/

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

    function name() external pure returns (string memory);

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

    function decimals() external pure returns (uint8);

    function totalSupply() external view returns (uint256);

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

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

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

    function transfer(address to, uint256 value) external returns (bool);

    function transferFrom(
        address from,
        address to,
        uint256 value
    ) external returns (bool);

    function DOMAIN_SEPARATOR() external view returns (bytes32);

    function PERMIT_TYPEHASH() external pure returns (bytes32);

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

    function permit(
        address owner,
        address spender,
        uint256 value,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external;

    /*** Pool Token ***/

    event Mint(
        address indexed sender,
        address indexed minter,
        uint256 mintAmount,
        uint256 mintTokens
    );
    event Redeem(
        address indexed sender,
        address indexed redeemer,
        uint256 redeemAmount,
        uint256 redeemTokens
    );
    event Sync(uint256 totalBalance);

    function underlying() external view returns (address);

    function factory() external view returns (address);

    function totalBalance() external view returns (uint256);

    function MINIMUM_LIQUIDITY() external pure returns (uint256);

    function exchangeRate() external returns (uint256);

    function mint(address minter) external returns (uint256 mintTokens);

    function redeem(address redeemer) external returns (uint256 redeemAmount);

    function skim(address to) external;

    function sync() external;

    function _setFactory() external;

    /*** Collateral ***/

    function borrowable0() external view returns (address);

    function borrowable1() external view returns (address);

    function tarotPriceOracle() external view returns (address);

    function safetyMarginSqrt() external view returns (uint256);

    function liquidationIncentive() external view returns (uint256);
 
    function liquidationFee() external view returns (uint256);

    function liquidationPenalty() external view returns (uint256);

    function getPrices() external returns (uint256 price0, uint256 price1);

    function tokensUnlocked(address from, uint256 value)
        external
        returns (bool);

    function accountLiquidityAmounts(
        address account,
        uint256 amount0,
        uint256 amount1
    ) external returns (uint256 liquidity, uint256 shortfall);

    function accountLiquidity(address account)
        external
        returns (uint256 liquidity, uint256 shortfall);

    function canBorrow(
        address account,
        address borrowable,
        uint256 accountBorrows
    ) external returns (bool);

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

    function flashRedeem(
        address redeemer,
        uint256 redeemAmount,
        bytes calldata data
    ) external;

    /*** Collateral Setter ***/

    event NewSafetyMargin(uint256 newSafetyMarginSqrt);
    event NewLiquidationIncentive(uint256 newLiquidationIncentive);
    event NewLiquidationFee(uint256 newLiquidationFee);

    function SAFETY_MARGIN_SQRT_MIN() external pure returns (uint256);

    function SAFETY_MARGIN_SQRT_MAX() external pure returns (uint256);

    function LIQUIDATION_INCENTIVE_MIN() external pure returns (uint256);

    function LIQUIDATION_INCENTIVE_MAX() external pure returns (uint256);

    function LIQUIDATION_FEE_MAX() external pure returns (uint256);

    function _initialize(
        string calldata _name,
        string calldata _symbol,
        address _underlying,
        address _borrowable0,
        address _borrowable1
    ) external;

    function _setSafetyMarginSqrt(uint256 newSafetyMarginSqrt) external;

    function _setLiquidationIncentive(uint256 newLiquidationIncentive) external;

    function _setLiquidationFee(uint256 newLiquidationFee) external;
}

// File: contracts/interfaces/ITarotCallee.sol



pragma solidity >=0.5.0;

interface ITarotCallee {
    function tarotBorrow(
        address sender,
        address borrower,
        uint256 borrowAmount,
        bytes calldata data
    ) external;

    function tarotRedeem(
        address sender,
        uint256 redeemAmount,
        bytes calldata data
    ) external;
}

// File: contracts/interfaces/IERC20.sol



pragma solidity >=0.5.0;

interface IERC20 {
    event Approval(address indexed owner, address indexed spender, uint value);
    event Transfer(address indexed from, address indexed to, uint value);

    function name() external view returns (string memory);
    function symbol() external view returns (string memory);
    function decimals() external view returns (uint8);
    function totalSupply() external view returns (uint);
    function balanceOf(address owner) external view returns (uint);
    function allowance(address owner, address spender) external view returns (uint);

    function approve(address spender, uint value) external returns (bool);
    function transfer(address to, uint value) external returns (bool);
    function transferFrom(address from, address to, uint value) external returns (bool);
}

// File: contracts/interfaces/IFactory.sol



pragma solidity >=0.5.0;

interface IFactory {
	event LendingPoolInitialized(address indexed uniswapV2Pair, address indexed token0, address indexed token1,
		address collateral, address borrowable0, address borrowable1, uint lendingPoolId);
	event NewPendingAdmin(address oldPendingAdmin, address newPendingAdmin);
	event NewAdmin(address oldAdmin, address newAdmin);
	event NewReservesPendingAdmin(address oldReservesPendingAdmin, address newReservesPendingAdmin);
	event NewReservesAdmin(address oldReservesAdmin, address newReservesAdmin);
	event NewReservesManager(address oldReservesManager, address newReservesManager);
	
	function admin() external view returns (address);
	function pendingAdmin() external view returns (address);
	function reservesAdmin() external view returns (address);
	function reservesPendingAdmin() external view returns (address);
	function reservesManager() external view returns (address);

	function getLendingPool(address uniswapV2Pair) external view returns (
		bool initialized, 
		uint24 lendingPoolId, 
		address collateral, 
		address borrowable0, 
		address borrowable1
	);
	function allLendingPools(uint) external view returns (address uniswapV2Pair);
	function allLendingPoolsLength() external view returns (uint);
	
	function bDeployer() external view returns (address);
	function cDeployer() external view returns (address);
	function tarotPriceOracle() external view returns (address);

	function createCollateral(address uniswapV2Pair) external returns (address collateral);
	function createBorrowable0(address uniswapV2Pair) external returns (address borrowable0);
	function createBorrowable1(address uniswapV2Pair) external returns (address borrowable1);
	function initializeLendingPool(address uniswapV2Pair) external;

	function _setPendingAdmin(address newPendingAdmin) external;
	function _acceptAdmin() external;
	function _setReservesPendingAdmin(address newPendingAdmin) external;
	function _acceptReservesAdmin() external;
	function _setReservesManager(address newReservesManager) external;
}

// File: contracts/interfaces/IBorrowTracker.sol



pragma solidity >=0.5.0;

interface IBorrowTracker {
	function trackBorrow(address borrower, uint borrowBalance, uint borrowIndex) external;
}
// File: contracts/libraries/Math.sol



pragma solidity =0.5.16;

// a library for performing various math operations
// forked from: https://github.com/Uniswap/uniswap-v2-core/blob/master/contracts/libraries/Math.sol

library Math {
    function min(uint x, uint y) internal pure returns (uint z) {
        z = x < y ? x : y;
    }

    // babylonian method (https://en.wikipedia.org/wiki/Methods_of_computing_square_roots#Babylonian_method)
    function sqrt(uint y) internal pure returns (uint z) {
        if (y > 3) {
            z = y;
            uint x = y / 2 + 1;
            while (x < z) {
                z = x;
                x = (y / x + x) / 2;
            }
        } else if (y != 0) {
            z = 1;
        }
    }
}

// File: contracts/TarotERC20.sol



pragma solidity =0.5.16;

import "./libraries/SafeMath.sol";

// This contract is basically UniswapV2ERC20 with small modifications
// src: https://github.com/Uniswap/uniswap-v2-core/blob/master/contracts/UniswapV2ERC20.sol

contract TarotERC20 {
    using SafeMath for uint256;

    string public name;
    string public symbol;
    uint8 public decimals = 18;
    uint256 public totalSupply;
    mapping(address => uint256) public balanceOf;
    mapping(address => mapping(address => uint256)) public allowance;

    bytes32 public DOMAIN_SEPARATOR;
    mapping(address => uint256) public nonces;

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

    constructor() public {}

    function _setName(string memory _name, string memory _symbol) internal {
        name = _name;
        symbol = _symbol;
        uint256 chainId;
        assembly {
            chainId := chainid
        }
        DOMAIN_SEPARATOR = keccak256(
            abi.encode(
                keccak256(
                    "EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)"
                ),
                keccak256(bytes(_name)),
                keccak256(bytes("1")),
                chainId,
                address(this)
            )
        );
    }

    function _mint(address to, uint256 value) internal {
        totalSupply = totalSupply.add(value);
        balanceOf[to] = balanceOf[to].add(value);
        emit Transfer(address(0), to, value);
    }

    function _burn(address from, uint256 value) internal {
        balanceOf[from] = balanceOf[from].sub(value);
        totalSupply = totalSupply.sub(value);
        emit Transfer(from, address(0), value);
    }

    function _approve(
        address owner,
        address spender,
        uint256 value
    ) private {
        allowance[owner][spender] = value;
        emit Approval(owner, spender, value);
    }

    function _transfer(
        address from,
        address to,
        uint256 value
    ) internal {
        balanceOf[from] = balanceOf[from].sub(
            value,
            "Tarot: TRANSFER_TOO_HIGH"
        );
        balanceOf[to] = balanceOf[to].add(value);
        emit Transfer(from, to, value);
    }

    function approve(address spender, uint256 value) external returns (bool) {
        _approve(msg.sender, spender, value);
        return true;
    }

    function transfer(address to, uint256 value) external returns (bool) {
        _transfer(msg.sender, to, value);
        return true;
    }

    function transferFrom(
        address from,
        address to,
        uint256 value
    ) external returns (bool) {
        if (allowance[from][msg.sender] != uint256(-1)) {
            allowance[from][msg.sender] = allowance[from][msg.sender].sub(
                value,
                "Tarot: TRANSFER_NOT_ALLOWED"
            );
        }
        _transfer(from, to, value);
        return true;
    }

    function _checkSignature(
        address owner,
        address spender,
        uint256 value,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s,
        bytes32 typehash
    ) internal {
        require(deadline >= block.timestamp, "Tarot: EXPIRED");
        bytes32 digest =
            keccak256(
                abi.encodePacked(
                    "\x19\x01",
                    DOMAIN_SEPARATOR,
                    keccak256(
                        abi.encode(
                            typehash,
                            owner,
                            spender,
                            value,
                            nonces[owner]++,
                            deadline
                        )
                    )
                )
            );
        address recoveredAddress = ecrecover(digest, v, r, s);
        require(
            recoveredAddress != address(0) && recoveredAddress == owner,
            "Tarot: INVALID_SIGNATURE"
        );
    }

    // keccak256("Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)");
    bytes32 public constant PERMIT_TYPEHASH =
        0x6e71edae12b1b97f4d1f60370fef10105fa2faae0126114a169c64845d6126c9;

    function permit(
        address owner,
        address spender,
        uint256 value,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external {
        _checkSignature(
            owner,
            spender,
            value,
            deadline,
            v,
            r,
            s,
            PERMIT_TYPEHASH
        );
        _approve(owner, spender, value);
    }
}

// File: contracts/interfaces/IPoolToken.sol



pragma solidity >=0.5.0;

interface IPoolToken {
    /*** Tarot ERC20 ***/

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

    function name() external pure returns (string memory);

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

    function decimals() external pure returns (uint8);

    function totalSupply() external view returns (uint256);

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

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

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

    function transfer(address to, uint256 value) external returns (bool);

    function transferFrom(
        address from,
        address to,
        uint256 value
    ) external returns (bool);

    function DOMAIN_SEPARATOR() external view returns (bytes32);

    function PERMIT_TYPEHASH() external pure returns (bytes32);

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

    function permit(
        address owner,
        address spender,
        uint256 value,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external;

    /*** Pool Token ***/

    event Mint(
        address indexed sender,
        address indexed minter,
        uint256 mintAmount,
        uint256 mintTokens
    );
    event Redeem(
        address indexed sender,
        address indexed redeemer,
        uint256 redeemAmount,
        uint256 redeemTokens
    );
    event Sync(uint256 totalBalance);

    function underlying() external view returns (address);

    function factory() external view returns (address);

    function totalBalance() external view returns (uint256);

    function MINIMUM_LIQUIDITY() external pure returns (uint256);

    function exchangeRate() external returns (uint256);

    function mint(address minter) external returns (uint256 mintTokens);

    function redeem(address redeemer) external returns (uint256 redeemAmount);

    function skim(address to) external;

    function sync() external;

    function _setFactory() external;
}

// File: contracts/libraries/SafeMath.sol



pragma solidity =0.5.16;

// From https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/math/Math.sol
// Subject to the MIT license.

/**
 * @dev Wrappers over Solidity's arithmetic operations with added overflow
 * checks.
 *
 * Arithmetic operations in Solidity wrap on overflow. This can easily result
 * in bugs, because programmers usually assume that an overflow raises an
 * error, which is the standard behavior in high level programming languages.
 * `SafeMath` restores this intuition by reverting the transaction when an
 * operation overflows.
 *
 * Using this library instead of the unchecked operations eliminates an entire
 * class of bugs, so it's recommended to use it always.
 */
library SafeMath {
    /**
     * @dev Returns the addition of two unsigned integers, reverting on overflow.
     *
     * Counterpart to Solidity's `+` operator.
     *
     * Requirements:
     * - Addition cannot overflow.
     */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a, "SafeMath: addition overflow");

        return c;
    }

    /**
     * @dev Returns the addition of two unsigned integers, reverting with custom message on overflow.
     *
     * Counterpart to Solidity's `+` operator.
     *
     * Requirements:
     * - Addition cannot overflow.
     */
    function add(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a, errorMessage);

        return c;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting on underflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     * - Subtraction cannot underflow.
     */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        return sub(a, b, "SafeMath: subtraction underflow");
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on underflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     * - Subtraction cannot underflow.
     */
    function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b <= a, errorMessage);
        uint256 c = a - b;

        return c;
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, reverting on overflow.
     *
     * Counterpart to Solidity's `*` operator.
     *
     * Requirements:
     * - Multiplication cannot overflow.
     */
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
        // benefit is lost if 'b' is also tested.
        // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
        if (a == 0) {
            return 0;
        }

        uint256 c = a * b;
        require(c / a == b, "SafeMath: multiplication overflow");

        return c;
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, reverting on overflow.
     *
     * Counterpart to Solidity's `*` operator.
     *
     * Requirements:
     * - Multiplication cannot overflow.
     */
    function mul(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
        // benefit is lost if 'b' is also tested.
        // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
        if (a == 0) {
            return 0;
        }

        uint256 c = a * b;
        require(c / a == b, errorMessage);

        return c;
    }

    /**
     * @dev Returns the integer division of two unsigned integers.
     * Reverts on division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        return div(a, b, "SafeMath: division by zero");
    }

    /**
     * @dev Returns the integer division of two unsigned integers.
     * Reverts with custom message on division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        // Solidity only automatically asserts when dividing by 0
        require(b > 0, errorMessage);
        uint256 c = a / b;
        // assert(a == b * c + a % b); // There is no case in which this doesn't hold

        return c;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        return mod(a, b, "SafeMath: modulo by zero");
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts with custom message when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b != 0, errorMessage);
        return a % b;
    }
}