// File: contracts/JumpRateModelV2.sol



// SPDX-License-Identifier: MIT

pragma solidity 0.6.12;

import "./BaseJumpRateModelV2.sol";
import "./InterestRateModel.sol";

/**
 * @title Compound's JumpRateModel Contract V2 for V2 cTokens
 * @author Arr00
 * @notice Supports only for V2 cTokens
 */
contract JumpRateModelV2 is InterestRateModel, BaseJumpRateModelV2 {
    /**
     * @notice Calculates the current borrow rate per block
     * @param cash The amount of cash in the market
     * @param borrows The amount of borrows in the market
     * @param reserves The amount of reserves in the market
     * @return The borrow rate percentage per block as a mantissa (scaled by 1e18)
     */
    function getBorrowRate(
        uint cash,
        uint borrows,
        uint reserves
    ) external view override returns (uint) {
        return getBorrowRateInternal(cash, borrows, reserves);
    }

    /**
     * @notice Calculates the current supply rate per block
     * @param cash The amount of cash in the market
     * @param borrows The amount of borrows in the market
     * @param reserves The amount of reserves in the market
     * @param reserveFactorMantissa The current reserve factor for the market
     * @return The supply rate percentage per block as a mantissa (scaled by 1e18)
     */
    function getSupplyRate(
        uint cash,
        uint borrows,
        uint reserves,
        uint reserveFactorMantissa
    )
        public
        view
        virtual
        override(InterestRateModel, BaseJumpRateModelV2)
        returns (uint)
    {
        uint oneMinusReserveFactor = uint(1e18).sub(reserveFactorMantissa);
        uint borrowRate = getBorrowRateInternal(cash, borrows, reserves);
        uint rateToPool = borrowRate.mul(oneMinusReserveFactor).div(1e18);
        return
            utilizationRate(cash, borrows, reserves).mul(rateToPool).div(1e18);
    }

    constructor(
        uint baseRatePerYear,
        uint multiplierPerYear,
        uint jumpMultiplierPerYear,
        uint kink_,
        address owner_
    )
        public
        BaseJumpRateModelV2(
            baseRatePerYear,
            multiplierPerYear,
            jumpMultiplierPerYear,
            kink_,
            owner_
        )
    {}
}

// File: contracts/BaseJumpRateModelV2.sol



// SPDX-License-Identifier: MIT

pragma solidity 0.6.12;

import "./SafeMath.sol";

/**
 * @title Logic for Compound's JumpRateModel Contract V2.
 * @author Compound (modified by Dharma Labs, refactored by Arr00)
 * @notice Version 2 modifies Version 1 by enabling updateable parameters.
 */
abstract contract BaseJumpRateModelV2 {
    using SafeMath for uint;

    event NewInterestParams(
        uint baseRatePerBlock,
        uint multiplierPerBlock,
        uint jumpMultiplierPerBlock,
        uint kink
    );

    /**
     * @notice The address of the owner, i.e. the Timelock contract, which can update parameters directly
     */
    address public owner;

    /**
     * @notice The approximate number of blocks per year that is assumed by the interest rate model
     */
    uint public constant blocksPerYear = 2102400;

    /**
     * @notice The multiplier of utilization rate that gives the slope of the interest rate
     */
    uint public multiplierPerBlock;

    /**
     * @notice The base interest rate which is the y-intercept when utilization rate is 0
     */
    uint public baseRatePerBlock;

    /**
     * @notice The multiplierPerBlock after hitting a specified utilization point
     */
    uint public jumpMultiplierPerBlock;

    /**
     * @notice The utilization point at which the jump multiplier is applied
     */
    uint public kink;

    /**
     * @notice Construct an interest rate model
     * @param baseRatePerYear The approximate target base APR, as a mantissa (scaled by 1e18)
     * @param multiplierPerYear The rate of increase in interest rate wrt utilization (scaled by 1e18)
     * @param jumpMultiplierPerYear The multiplierPerBlock after hitting a specified utilization point
     * @param kink_ The utilization point at which the jump multiplier is applied
     * @param owner_ The address of the owner, i.e. the Timelock contract (which has the ability to update parameters directly)
     */
    constructor(
        uint baseRatePerYear,
        uint multiplierPerYear,
        uint jumpMultiplierPerYear,
        uint kink_,
        address owner_
    ) internal {
        owner = owner_;

        updateJumpRateModelInternal(
            baseRatePerYear,
            multiplierPerYear,
            jumpMultiplierPerYear,
            kink_
        );
    }

    /**
     * @notice Update Owner Address
     */
    function transferOwnership(address _owner) external {
        require(msg.sender == owner, "only the owner may call this function.");
        owner = _owner;
    }

    /**
     * @notice Update the parameters of the interest rate model (only callable by owner, i.e. Timelock)
     * @param baseRatePerYear The approximate target base APR, as a mantissa (scaled by 1e18)
     * @param multiplierPerYear The rate of increase in interest rate wrt utilization (scaled by 1e18)
     * @param jumpMultiplierPerYear The multiplierPerBlock after hitting a specified utilization point
     * @param kink_ The utilization point at which the jump multiplier is applied
     */
    function updateJumpRateModel(
        uint baseRatePerYear,
        uint multiplierPerYear,
        uint jumpMultiplierPerYear,
        uint kink_
    ) external virtual {
        require(msg.sender == owner, "only the owner may call this function.");

        updateJumpRateModelInternal(
            baseRatePerYear,
            multiplierPerYear,
            jumpMultiplierPerYear,
            kink_
        );
    }

    /**
     * @notice Calculates the utilization rate of the market: `borrows / (cash + borrows - reserves)`
     * @param cash The amount of cash in the market
     * @param borrows The amount of borrows in the market
     * @param reserves The amount of reserves in the market (currently unused)
     * @return The utilization rate as a mantissa between [0, 1e18]
     */
    function utilizationRate(
        uint cash,
        uint borrows,
        uint reserves
    ) public pure returns (uint) {
        // Utilization rate is 0 when there are no borrows
        if (borrows == 0) {
            return 0;
        }

        return borrows.mul(1e18).div(cash.add(borrows).sub(reserves));
    }

    /**
     * @notice Calculates the current borrow rate per block, with the error code expected by the market
     * @param cash The amount of cash in the market
     * @param borrows The amount of borrows in the market
     * @param reserves The amount of reserves in the market
     * @return The borrow rate percentage per block as a mantissa (scaled by 1e18)
     */
    function getBorrowRateInternal(
        uint cash,
        uint borrows,
        uint reserves
    ) internal view returns (uint) {
        uint util = utilizationRate(cash, borrows, reserves);

        if (util <= kink) {
            return util.mul(multiplierPerBlock).div(1e18).add(baseRatePerBlock);
        } else {
            uint normalRate = kink.mul(multiplierPerBlock).div(1e18).add(
                baseRatePerBlock
            );
            uint excessUtil = util.sub(kink);
            return
                excessUtil.mul(jumpMultiplierPerBlock).div(1e18).add(
                    normalRate
                );
        }
    }

    /**
     * @notice Calculates the current supply rate per block
     * @param cash The amount of cash in the market
     * @param borrows The amount of borrows in the market
     * @param reserves The amount of reserves in the market
     * @param reserveFactorMantissa The current reserve factor for the market
     * @return The supply rate percentage per block as a mantissa (scaled by 1e18)
     */
    function getSupplyRate(
        uint cash,
        uint borrows,
        uint reserves,
        uint reserveFactorMantissa
    ) public view virtual returns (uint) {
        uint oneMinusReserveFactor = uint(1e18).sub(reserveFactorMantissa);
        uint borrowRate = getBorrowRateInternal(cash, borrows, reserves);
        uint rateToPool = borrowRate.mul(oneMinusReserveFactor).div(1e18);
        return
            utilizationRate(cash, borrows, reserves).mul(rateToPool).div(1e18);
    }

    /**
     * @notice Internal function to update the parameters of the interest rate model
     * @param baseRatePerYear The approximate target base APR, as a mantissa (scaled by 1e18)
     * @param multiplierPerYear The rate of increase in interest rate wrt utilization (scaled by 1e18)
     * @param jumpMultiplierPerYear The multiplierPerBlock after hitting a specified utilization point
     * @param kink_ The utilization point at which the jump multiplier is applied
     */
    function updateJumpRateModelInternal(
        uint baseRatePerYear,
        uint multiplierPerYear,
        uint jumpMultiplierPerYear,
        uint kink_
    ) internal {
        baseRatePerBlock = baseRatePerYear.div(blocksPerYear);
        multiplierPerBlock = (multiplierPerYear.mul(1e18)).div(
            blocksPerYear.mul(kink_)
        );
        jumpMultiplierPerBlock = jumpMultiplierPerYear.div(blocksPerYear);
        kink = kink_;

        emit NewInterestParams(
            baseRatePerBlock,
            multiplierPerBlock,
            jumpMultiplierPerBlock,
            kink
        );
    }
}

// File: contracts/InterestRateModel.sol



// SPDX-License-Identifier: MIT

pragma solidity 0.6.12;

/**
 * @title Compound's InterestRateModel Interface
 * @author Compound
 */
abstract 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(
        uint cash,
        uint borrows,
        uint reserves
    ) external view virtual returns (uint);

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

// File: contracts/SafeMath.sol



// SPDX-License-Identifier: MIT

pragma solidity 0.6.12;

// 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;
    }
}