// SPDX-License-Identifier: AGPL-3.0-or-later
pragma solidity 0.8.6;


struct BassetPersonal {
    // Address of the bAsset
    address addr;
    // Address of the bAsset
    address integrator;
    // An ERC20 can charge transfer fee, for example USDT, DGX tokens.
    bool hasTxFee; // takes a byte in storage
    // Status of the bAsset
    BassetStatus status;
}

struct BassetData {
    // 1 Basset * ratio / ratioScale == x Masset (relative value)
    // If ratio == 10e8 then 1 bAsset = 10 mAssets
    // A ratio is divised as 10^(18-tokenDecimals) * measurementMultiple(relative value of 1 base unit)
    uint128 ratio;
    // Amount of the Basset that is held in Collateral
    uint128 vaultBalance;
}

// Status of the Basset - has it broken its peg?
enum BassetStatus {
    Default,
    Normal,
    BrokenBelowPeg,
    BrokenAbovePeg,
    Blacklisted,
    Liquidating,
    Liquidated,
    Fail
}

abstract contract IMasset {
    // Mint
    function mint(
        address _input,
        uint256 _inputQuantity,
        uint256 _minOutputQuantity,
        address _recipient
    ) external virtual returns (uint256 mintOutput);

    function mintMulti(
        address[] calldata _inputs,
        uint256[] calldata _inputQuantities,
        uint256 _minOutputQuantity,
        address _recipient
    ) external virtual returns (uint256 mintOutput);

    function getMintOutput(address _input, uint256 _inputQuantity)
        external
        view
        virtual
        returns (uint256 mintOutput);

    function getMintMultiOutput(address[] calldata _inputs, uint256[] calldata _inputQuantities)
        external
        view
        virtual
        returns (uint256 mintOutput);

    // Swaps
    function swap(
        address _input,
        address _output,
        uint256 _inputQuantity,
        uint256 _minOutputQuantity,
        address _recipient
    ) external virtual returns (uint256 swapOutput);

    function getSwapOutput(
        address _input,
        address _output,
        uint256 _inputQuantity
    ) external view virtual returns (uint256 swapOutput);

    // Redemption
    function redeem(
        address _output,
        uint256 _mAssetQuantity,
        uint256 _minOutputQuantity,
        address _recipient
    ) external virtual returns (uint256 outputQuantity);

    function redeemMasset(
        uint256 _mAssetQuantity,
        uint256[] calldata _minOutputQuantities,
        address _recipient
    ) external virtual returns (uint256[] memory outputQuantities);

    function redeemExactBassets(
        address[] calldata _outputs,
        uint256[] calldata _outputQuantities,
        uint256 _maxMassetQuantity,
        address _recipient
    ) external virtual returns (uint256 mAssetRedeemed);

    function getRedeemOutput(address _output, uint256 _mAssetQuantity)
        external
        view
        virtual
        returns (uint256 bAssetOutput);

    function getRedeemExactBassetsOutput(
        address[] calldata _outputs,
        uint256[] calldata _outputQuantities
    ) external view virtual returns (uint256 mAssetAmount);

    // Views
    function getBasket() external view virtual returns (bool, bool);

    function getBasset(address _token)
        external
        view
        virtual
        returns (BassetPersonal memory personal, BassetData memory data);

    function getBassets()
        external
        view
        virtual
        returns (BassetPersonal[] memory personal, BassetData[] memory data);

    function bAssetIndexes(address) external view virtual returns (uint8);

    function getPrice() external view virtual returns (uint256 price, uint256 k);

    // SavingsManager
    function collectInterest() external virtual returns (uint256 swapFeesGained, uint256 newSupply);

    function collectPlatformInterest()
        external
        virtual
        returns (uint256 mintAmount, uint256 newSupply);

    // Admin
    function setCacheSize(uint256 _cacheSize) external virtual;

    function setFees(uint256 _swapFee, uint256 _redemptionFee) external virtual;

    function setTransferFeesFlag(address _bAsset, bool _flag) external virtual;

    function migrateBassets(address[] calldata _bAssets, address _newIntegration) external virtual;
}

interface IERC20 {
    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns the amount of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);

    /**
     * @dev Moves `amount` tokens from the caller's account to `recipient`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address recipient, uint256 amount) external returns (bool);

    /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}. This is
     * zero by default.
     *
     * This value changes when {approve} or {transferFrom} are called.
     */
    function allowance(address owner, address spender) external view returns (uint256);

    /**
     * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * IMPORTANT: Beware that changing an allowance with this method brings the risk
     * that someone may use both the old and the new allowance by unfortunate
     * transaction ordering. One possible solution to mitigate this race
     * condition is to first reduce the spender's allowance to 0 and set the
     * desired value afterwards:
     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
     *
     * Emits an {Approval} event.
     */
    function approve(address spender, uint256 amount) external returns (bool);

    /**
     * @dev Moves `amount` tokens from `sender` to `recipient` using the
     * allowance mechanism. `amount` is then deducted from the caller's
     * allowance.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(
        address sender,
        address recipient,
        uint256 amount
    ) external returns (bool);

    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}. `value` is the new allowance.
     */
    event Approval(address indexed owner, address indexed spender, uint256 value);
}

interface ISavingsContractV2 {
    // DEPRECATED but still backwards compatible
    function redeem(uint256 _amount) external returns (uint256 massetReturned);

    function creditBalances(address) external view returns (uint256); // V1 & V2 (use balanceOf)

    // --------------------------------------------

    function depositInterest(uint256 _amount) external; // V1 & V2

    function depositSavings(uint256 _amount) external returns (uint256 creditsIssued); // V1 & V2

    function depositSavings(uint256 _amount, address _beneficiary)
        external
        returns (uint256 creditsIssued); // V2

    function redeemCredits(uint256 _amount) external returns (uint256 underlyingReturned); // V2

    function redeemUnderlying(uint256 _amount) external returns (uint256 creditsBurned); // V2

    function exchangeRate() external view returns (uint256); // V1 & V2

    function balanceOfUnderlying(address _user) external view returns (uint256 underlying); // V2

    function underlyingToCredits(uint256 _underlying) external view returns (uint256 credits); // V2

    function creditsToUnderlying(uint256 _credits) external view returns (uint256 underlying); // V2

    function underlying() external view returns (IERC20 underlyingMasset); // V2
}

interface IRevenueRecipient {
    /** @dev Recipient */
    function notifyRedistributionAmount(address _mAsset, uint256 _amount) external;

    function depositToPool(address[] calldata _mAssets, uint256[] calldata _percentages) external;
}

interface ISavingsManager {
    /** @dev Admin privs */
    function distributeUnallocatedInterest(address _mAsset) external;

    /** @dev Liquidator */
    function depositLiquidation(address _mAsset, uint256 _liquidation) external;

    /** @dev Liquidator */
    function collectAndStreamInterest(address _mAsset) external;

    /** @dev Public privs */
    function collectAndDistributeInterest(address _mAsset) external;

    /** @dev getter for public lastBatchCollected mapping */
    function lastBatchCollected(address _mAsset) external view returns (uint256);
}

contract ModuleKeys {
    // Governance
    // ===========
    // keccak256("Governance");
    bytes32 internal constant KEY_GOVERNANCE =
        0x9409903de1e6fd852dfc61c9dacb48196c48535b60e25abf92acc92dd689078d;
    //keccak256("Staking");
    bytes32 internal constant KEY_STAKING =
        0x1df41cd916959d1163dc8f0671a666ea8a3e434c13e40faef527133b5d167034;
    //keccak256("ProxyAdmin");
    bytes32 internal constant KEY_PROXY_ADMIN =
        0x96ed0203eb7e975a4cbcaa23951943fa35c5d8288117d50c12b3d48b0fab48d1;

    // mStable
    // =======
    // keccak256("OracleHub");
    bytes32 internal constant KEY_ORACLE_HUB =
        0x8ae3a082c61a7379e2280f3356a5131507d9829d222d853bfa7c9fe1200dd040;
    // keccak256("Manager");
    bytes32 internal constant KEY_MANAGER =
        0x6d439300980e333f0256d64be2c9f67e86f4493ce25f82498d6db7f4be3d9e6f;
    //keccak256("Recollateraliser");
    bytes32 internal constant KEY_RECOLLATERALISER =
        0x39e3ed1fc335ce346a8cbe3e64dd525cf22b37f1e2104a755e761c3c1eb4734f;
    //keccak256("MetaToken");
    bytes32 internal constant KEY_META_TOKEN =
        0xea7469b14936af748ee93c53b2fe510b9928edbdccac3963321efca7eb1a57a2;
    // keccak256("SavingsManager");
    bytes32 internal constant KEY_SAVINGS_MANAGER =
        0x12fe936c77a1e196473c4314f3bed8eeac1d757b319abb85bdda70df35511bf1;
    // keccak256("Liquidator");
    bytes32 internal constant KEY_LIQUIDATOR =
        0x1e9cb14d7560734a61fa5ff9273953e971ff3cd9283c03d8346e3264617933d4;
    // keccak256("InterestValidator");
    bytes32 internal constant KEY_INTEREST_VALIDATOR =
        0xc10a28f028c7f7282a03c90608e38a4a646e136e614e4b07d119280c5f7f839f;
}

interface INexus {
    function governor() external view returns (address);

    function getModule(bytes32 key) external view returns (address);

    function proposeModule(bytes32 _key, address _addr) external;

    function cancelProposedModule(bytes32 _key) external;

    function acceptProposedModule(bytes32 _key) external;

    function acceptProposedModules(bytes32[] calldata _keys) external;

    function requestLockModule(bytes32 _key) external;

    function cancelLockModule(bytes32 _key) external;

    function lockModule(bytes32 _key) external;
}

abstract contract ImmutableModule is ModuleKeys {
    INexus public immutable nexus;

    /**
     * @dev Initialization function for upgradable proxy contracts
     * @param _nexus Nexus contract address
     */
    constructor(address _nexus) {
        require(_nexus != address(0), "Nexus address is zero");
        nexus = INexus(_nexus);
    }

    /**
     * @dev Modifier to allow function calls only from the Governor.
     */
    modifier onlyGovernor() {
        _onlyGovernor();
        _;
    }

    function _onlyGovernor() internal view {
        require(msg.sender == _governor(), "Only governor can execute");
    }

    /**
     * @dev Modifier to allow function calls only from the Governance.
     *      Governance is either Governor address or Governance address.
     */
    modifier onlyGovernance() {
        require(
            msg.sender == _governor() || msg.sender == _governance(),
            "Only governance can execute"
        );
        _;
    }

    /**
     * @dev Returns Governor address from the Nexus
     * @return Address of Governor Contract
     */
    function _governor() internal view returns (address) {
        return nexus.governor();
    }

    /**
     * @dev Returns Governance Module address from the Nexus
     * @return Address of the Governance (Phase 2)
     */
    function _governance() internal view returns (address) {
        return nexus.getModule(KEY_GOVERNANCE);
    }

    /**
     * @dev Return SavingsManager Module address from the Nexus
     * @return Address of the SavingsManager Module contract
     */
    function _savingsManager() internal view returns (address) {
        return nexus.getModule(KEY_SAVINGS_MANAGER);
    }

    /**
     * @dev Return Recollateraliser Module address from the Nexus
     * @return  Address of the Recollateraliser Module contract (Phase 2)
     */
    function _recollateraliser() internal view returns (address) {
        return nexus.getModule(KEY_RECOLLATERALISER);
    }

    /**
     * @dev Return Liquidator Module address from the Nexus
     * @return  Address of the Liquidator Module contract
     */
    function _liquidator() internal view returns (address) {
        return nexus.getModule(KEY_LIQUIDATOR);
    }

    /**
     * @dev Return ProxyAdmin Module address from the Nexus
     * @return Address of the ProxyAdmin Module contract
     */
    function _proxyAdmin() internal view returns (address) {
        return nexus.getModule(KEY_PROXY_ADMIN);
    }
}

abstract contract PausableModule is ImmutableModule {
    /**
     * @dev Emitted when the pause is triggered by Governor
     */
    event Paused(address account);

    /**
     * @dev Emitted when the pause is lifted by Governor
     */
    event Unpaused(address account);

    bool internal _paused = false;

    /**
     * @dev Modifier to make a function callable only when the contract is not paused.
     */
    modifier whenNotPaused() {
        require(!_paused, "Pausable: paused");
        _;
    }

    /**
     * @dev Modifier to make a function callable only when the contract is paused.
     */
    modifier whenPaused() {
        require(_paused, "Pausable: not paused");
        _;
    }

    /**
     * @dev Initializes the contract in unpaused state.
     * Hooks into the Module to give the Governor ability to pause
     * @param _nexus Nexus contract address
     */
    constructor(address _nexus) ImmutableModule(_nexus) {
        _paused = false;
    }

    /**
     * @dev Returns true if the contract is paused, and false otherwise.
     * @return Returns `true` when paused, otherwise `false`
     */
    function paused() external view returns (bool) {
        return _paused;
    }

    /**
     * @dev Called by the Governor to pause, triggers stopped state.
     */
    function pause() external onlyGovernor whenNotPaused {
        _paused = true;
        emit Paused(msg.sender);
    }

    /**
     * @dev Called by Governor to unpause, returns to normal state.
     */
    function unpause() external onlyGovernor whenPaused {
        _paused = false;
        emit Unpaused(msg.sender);
    }
}

/**
 * @dev Collection of functions related to the address type
 */
library Address {
    /**
     * @dev Returns true if `account` is a contract.
     *
     * [IMPORTANT]
     * ====
     * It is unsafe to assume that an address for which this function returns
     * false is an externally-owned account (EOA) and not a contract.
     *
     * Among others, `isContract` will return false for the following
     * types of addresses:
     *
     *  - an externally-owned account
     *  - a contract in construction
     *  - an address where a contract will be created
     *  - an address where a contract lived, but was destroyed
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize, which returns 0 for contracts in
        // construction, since the code is only stored at the end of the
        // constructor execution.

        uint256 size;
        assembly {
            size := extcodesize(account)
        }
        return size > 0;
    }

    /**
     * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
     * `recipient`, forwarding all available gas and reverting on errors.
     *
     * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
     * of certain opcodes, possibly making contracts go over the 2300 gas limit
     * imposed by `transfer`, making them unable to receive funds via
     * `transfer`. {sendValue} removes this limitation.
     *
     * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
     *
     * IMPORTANT: because control is transferred to `recipient`, care must be
     * taken to not create reentrancy vulnerabilities. Consider using
     * {ReentrancyGuard} or the
     * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");

        (bool success, ) = recipient.call{value: amount}("");
        require(success, "Address: unable to send value, recipient may have reverted");
    }

    /**
     * @dev Performs a Solidity function call using a low level `call`. A
     * plain `call` is an unsafe replacement for a function call: use this
     * function instead.
     *
     * If `target` reverts with a revert reason, it is bubbled up by this
     * function (like regular Solidity function calls).
     *
     * Returns the raw returned data. To convert to the expected return value,
     * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
     *
     * Requirements:
     *
     * - `target` must be a contract.
     * - calling `target` with `data` must not revert.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionCall(target, data, "Address: low-level call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
     * `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but also transferring `value` wei to `target`.
     *
     * Requirements:
     *
     * - the calling contract must have an ETH balance of at least `value`.
     * - the called Solidity function must be `payable`.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(
        address target,
        bytes memory data,
        uint256 value
    ) internal returns (bytes memory) {
        return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
    }

    /**
     * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
     * with `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(
        address target,
        bytes memory data,
        uint256 value,
        string memory errorMessage
    ) internal returns (bytes memory) {
        require(address(this).balance >= value, "Address: insufficient balance for call");
        require(isContract(target), "Address: call to non-contract");

        (bool success, bytes memory returndata) = target.call{value: value}(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
        return functionStaticCall(target, data, "Address: low-level static call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal view returns (bytes memory) {
        require(isContract(target), "Address: static call to non-contract");

        (bool success, bytes memory returndata) = target.staticcall(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionDelegateCall(target, data, "Address: low-level delegate call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        require(isContract(target), "Address: delegate call to non-contract");

        (bool success, bytes memory returndata) = target.delegatecall(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    function _verifyCallResult(
        bool success,
        bytes memory returndata,
        string memory errorMessage
    ) private pure returns (bytes memory) {
        if (success) {
            return returndata;
        } else {
            // Look for revert reason and bubble it up if present
            if (returndata.length > 0) {
                // The easiest way to bubble the revert reason is using memory via assembly

                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}

library SafeERC20 {
    using Address for address;

    function safeTransfer(
        IERC20 token,
        address to,
        uint256 value
    ) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
    }

    function safeTransferFrom(
        IERC20 token,
        address from,
        address to,
        uint256 value
    ) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transferFrom.selector, from, to, value));
    }

    /**
     * @dev Deprecated. This function has issues similar to the ones found in
     * {IERC20-approve}, and its usage is discouraged.
     *
     * Whenever possible, use {safeIncreaseAllowance} and
     * {safeDecreaseAllowance} instead.
     */
    function safeApprove(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        // safeApprove should only be called when setting an initial allowance,
        // or when resetting it to zero. To increase and decrease it, use
        // 'safeIncreaseAllowance' and 'safeDecreaseAllowance'
        require(
            (value == 0) || (token.allowance(address(this), spender) == 0),
            "SafeERC20: approve from non-zero to non-zero allowance"
        );
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, value));
    }

    function safeIncreaseAllowance(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        uint256 newAllowance = token.allowance(address(this), spender) + value;
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
    }

    function safeDecreaseAllowance(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        unchecked {
            uint256 oldAllowance = token.allowance(address(this), spender);
            require(oldAllowance >= value, "SafeERC20: decreased allowance below zero");
            uint256 newAllowance = oldAllowance - value;
            _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
        }
    }

    /**
     * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
     * on the return value: the return value is optional (but if data is returned, it must not be false).
     * @param token The token targeted by the call.
     * @param data The call data (encoded using abi.encode or one of its variants).
     */
    function _callOptionalReturn(IERC20 token, bytes memory data) private {
        // We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
        // we're implementing it ourselves. We use {Address.functionCall} to perform this call, which verifies that
        // the target address contains contract code and also asserts for success in the low-level call.

        bytes memory returndata = address(token).functionCall(data, "SafeERC20: low-level call failed");
        if (returndata.length > 0) {
            // Return data is optional
            require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
        }
    }
}

library StableMath {
    /**
     * @dev Scaling unit for use in specific calculations,
     * where 1 * 10**18, or 1e18 represents a unit '1'
     */
    uint256 private constant FULL_SCALE = 1e18;

    /**
     * @dev Token Ratios are used when converting between units of bAsset, mAsset and MTA
     * Reasoning: Takes into account token decimals, and difference in base unit (i.e. grams to Troy oz for gold)
     * bAsset ratio unit for use in exact calculations,
     * where (1 bAsset unit * bAsset.ratio) / ratioScale == x mAsset unit
     */
    uint256 private constant RATIO_SCALE = 1e8;

    /**
     * @dev Provides an interface to the scaling unit
     * @return Scaling unit (1e18 or 1 * 10**18)
     */
    function getFullScale() internal pure returns (uint256) {
        return FULL_SCALE;
    }

    /**
     * @dev Provides an interface to the ratio unit
     * @return Ratio scale unit (1e8 or 1 * 10**8)
     */
    function getRatioScale() internal pure returns (uint256) {
        return RATIO_SCALE;
    }

    /**
     * @dev Scales a given integer to the power of the full scale.
     * @param x   Simple uint256 to scale
     * @return    Scaled value a to an exact number
     */
    function scaleInteger(uint256 x) internal pure returns (uint256) {
        return x * FULL_SCALE;
    }

    /***************************************
              PRECISE ARITHMETIC
    ****************************************/

    /**
     * @dev Multiplies two precise units, and then truncates by the full scale
     * @param x     Left hand input to multiplication
     * @param y     Right hand input to multiplication
     * @return      Result after multiplying the two inputs and then dividing by the shared
     *              scale unit
     */
    function mulTruncate(uint256 x, uint256 y) internal pure returns (uint256) {
        return mulTruncateScale(x, y, FULL_SCALE);
    }

    /**
     * @dev Multiplies two precise units, and then truncates by the given scale. For example,
     * when calculating 90% of 10e18, (10e18 * 9e17) / 1e18 = (9e36) / 1e18 = 9e18
     * @param x     Left hand input to multiplication
     * @param y     Right hand input to multiplication
     * @param scale Scale unit
     * @return      Result after multiplying the two inputs and then dividing by the shared
     *              scale unit
     */
    function mulTruncateScale(
        uint256 x,
        uint256 y,
        uint256 scale
    ) internal pure returns (uint256) {
        // e.g. assume scale = fullScale
        // z = 10e18 * 9e17 = 9e36
        // return 9e36 / 1e18 = 9e18
        return (x * y) / scale;
    }

    /**
     * @dev Multiplies two precise units, and then truncates by the full scale, rounding up the result
     * @param x     Left hand input to multiplication
     * @param y     Right hand input to multiplication
     * @return      Result after multiplying the two inputs and then dividing by the shared
     *              scale unit, rounded up to the closest base unit.
     */
    function mulTruncateCeil(uint256 x, uint256 y) internal pure returns (uint256) {
        // e.g. 8e17 * 17268172638 = 138145381104e17
        uint256 scaled = x * y;
        // e.g. 138145381104e17 + 9.99...e17 = 138145381113.99...e17
        uint256 ceil = scaled + FULL_SCALE - 1;
        // e.g. 13814538111.399...e18 / 1e18 = 13814538111
        return ceil / FULL_SCALE;
    }

    /**
     * @dev Precisely divides two units, by first scaling the left hand operand. Useful
     *      for finding percentage weightings, i.e. 8e18/10e18 = 80% (or 8e17)
     * @param x     Left hand input to division
     * @param y     Right hand input to division
     * @return      Result after multiplying the left operand by the scale, and
     *              executing the division on the right hand input.
     */
    function divPrecisely(uint256 x, uint256 y) internal pure returns (uint256) {
        // e.g. 8e18 * 1e18 = 8e36
        // e.g. 8e36 / 10e18 = 8e17
        return (x * FULL_SCALE) / y;
    }

    /***************************************
                  RATIO FUNCS
    ****************************************/

    /**
     * @dev Multiplies and truncates a token ratio, essentially flooring the result
     *      i.e. How much mAsset is this bAsset worth?
     * @param x     Left hand operand to multiplication (i.e Exact quantity)
     * @param ratio bAsset ratio
     * @return c    Result after multiplying the two inputs and then dividing by the ratio scale
     */
    function mulRatioTruncate(uint256 x, uint256 ratio) internal pure returns (uint256 c) {
        return mulTruncateScale(x, ratio, RATIO_SCALE);
    }

    /**
     * @dev Multiplies and truncates a token ratio, rounding up the result
     *      i.e. How much mAsset is this bAsset worth?
     * @param x     Left hand input to multiplication (i.e Exact quantity)
     * @param ratio bAsset ratio
     * @return      Result after multiplying the two inputs and then dividing by the shared
     *              ratio scale, rounded up to the closest base unit.
     */
    function mulRatioTruncateCeil(uint256 x, uint256 ratio) internal pure returns (uint256) {
        // e.g. How much mAsset should I burn for this bAsset (x)?
        // 1e18 * 1e8 = 1e26
        uint256 scaled = x * ratio;
        // 1e26 + 9.99e7 = 100..00.999e8
        uint256 ceil = scaled + RATIO_SCALE - 1;
        // return 100..00.999e8 / 1e8 = 1e18
        return ceil / RATIO_SCALE;
    }

    /**
     * @dev Precisely divides two ratioed units, by first scaling the left hand operand
     *      i.e. How much bAsset is this mAsset worth?
     * @param x     Left hand operand in division
     * @param ratio bAsset ratio
     * @return c    Result after multiplying the left operand by the scale, and
     *              executing the division on the right hand input.
     */
    function divRatioPrecisely(uint256 x, uint256 ratio) internal pure returns (uint256 c) {
        // e.g. 1e14 * 1e8 = 1e22
        // return 1e22 / 1e12 = 1e10
        return (x * RATIO_SCALE) / ratio;
    }

    /***************************************
                    HELPERS
    ****************************************/

    /**
     * @dev Calculates minimum of two numbers
     * @param x     Left hand input
     * @param y     Right hand input
     * @return      Minimum of the two inputs
     */
    function min(uint256 x, uint256 y) internal pure returns (uint256) {
        return x > y ? y : x;
    }

    /**
     * @dev Calculated maximum of two numbers
     * @param x     Left hand input
     * @param y     Right hand input
     * @return      Maximum of the two inputs
     */
    function max(uint256 x, uint256 y) internal pure returns (uint256) {
        return x > y ? x : y;
    }

    /**
     * @dev Clamps a value to an upper bound
     * @param x           Left hand input
     * @param upperBound  Maximum possible value to return
     * @return            Input x clamped to a maximum value, upperBound
     */
    function clamp(uint256 x, uint256 upperBound) internal pure returns (uint256) {
        return x > upperBound ? upperBound : x;
    }
}

library YieldValidator {
    uint256 private constant SECONDS_IN_YEAR = 365 days;
    uint256 private constant THIRTY_MINUTES = 30 minutes;

    uint256 private constant MAX_APY = 15e18;
    uint256 private constant TEN_BPS = 1e15;

    /**
     * @dev Validates that an interest collection does not exceed a maximum APY. If last collection
     * was under 30 mins ago, simply check it does not exceed 10bps
     * @param _newSupply               New total supply of the mAsset
     * @param _interest                Increase in total supply since last collection
     * @param _timeSinceLastCollection Seconds since last collection
     */
    function validateCollection(
        uint256 _newSupply,
        uint256 _interest,
        uint256 _timeSinceLastCollection
    ) internal pure returns (uint256 extrapolatedAPY) {
        return
            validateCollection(_newSupply, _interest, _timeSinceLastCollection, MAX_APY, TEN_BPS);
    }

    /**
     * @dev Validates that an interest collection does not exceed a maximum APY. If last collection
     * was under 30 mins ago, simply check it does not exceed 10bps
     * @param _newSupply               New total supply of the mAsset
     * @param _interest                Increase in total supply since last collection
     * @param _timeSinceLastCollection Seconds since last collection
     * @param _maxApy                  Max APY where 100% == 1e18
     * @param _baseApy                 If less than 30 mins, do not exceed this % increase
     */
    function validateCollection(
        uint256 _newSupply,
        uint256 _interest,
        uint256 _timeSinceLastCollection,
        uint256 _maxApy,
        uint256 _baseApy
    ) internal pure returns (uint256 extrapolatedAPY) {
        uint256 protectedTime = _timeSinceLastCollection == 0 ? 1 : _timeSinceLastCollection;

        // Percentage increase in total supply
        // e.g. (1e20 * 1e18) / 1e24 = 1e14 (or a 0.01% increase)
        // e.g. (5e18 * 1e18) / 1.2e24 = 4.1667e12
        // e.g. (1e19 * 1e18) / 1e21 = 1e16
        uint256 oldSupply = _newSupply - _interest;
        uint256 percentageIncrease = (_interest * 1e18) / oldSupply;

        //      If over 30 mins, extrapolate APY
        // e.g. day: (86400 * 1e18) / 3.154e7 = 2.74..e15
        // e.g. 30 mins: (1800 * 1e18) / 3.154e7 = 5.7..e13
        // e.g. epoch: (1593596907 * 1e18) / 3.154e7 = 50.4..e18
        uint256 yearsSinceLastCollection = (protectedTime * 1e18) / SECONDS_IN_YEAR;

        // e.g. 0.01% (1e14 * 1e18) / 2.74..e15 = 3.65e16 or 3.65% apr
        // e.g. (4.1667e12 * 1e18) / 5.7..e13 = 7.1e16 or 7.1% apr
        // e.g. (1e16 * 1e18) / 50e18 = 2e14
        extrapolatedAPY = (percentageIncrease * 1e18) / yearsSinceLastCollection;

        if (protectedTime > THIRTY_MINUTES) {
            require(extrapolatedAPY < _maxApy, "Interest protected from inflating past maxAPY");
        } else {
            require(percentageIncrease < _baseApy, "Interest protected from inflating past 10 Bps");
        }
    }
}

/**
 * @title   SavingsManager
 * @author  mStable
 * @notice  Savings Manager collects interest from mAssets and sends them to the
 *          corresponding Savings Contract, performing some validation in the process.
 * @dev     VERSION: 1.4
 *          DATE:    2021-10-15
 */
contract SavingsManager is ISavingsManager, PausableModule {
    using StableMath for uint256;
    using SafeERC20 for IERC20;

    // Core admin events
    event RevenueRecipientSet(address indexed mAsset, address recipient);
    event SavingsContractAdded(address indexed mAsset, address savingsContract);
    event SavingsContractUpdated(address indexed mAsset, address savingsContract);
    event SavingsRateChanged(uint256 newSavingsRate);
    event StreamsFrozen();
    // Interest collection
    event LiquidatorDeposited(address indexed mAsset, uint256 amount);
    event InterestCollected(
        address indexed mAsset,
        uint256 interest,
        uint256 newTotalSupply,
        uint256 apy
    );
    event InterestDistributed(address indexed mAsset, uint256 amountSent);
    event RevenueRedistributed(address indexed mAsset, address recipient, uint256 amount);

    // Locations of each mAsset savings contract
    mapping(address => ISavingsContractV2) public savingsContracts;
    mapping(address => IRevenueRecipient) public revenueRecipients;
    // Time at which last collection was made
    mapping(address => uint256) public lastPeriodStart;
    mapping(address => uint256) public lastCollection;
    mapping(address => uint256) public periodYield;

    // Amount of collected interest that will be sent to Savings Contract (1e18 = 100%)
    uint256 private savingsRate;
    // Streaming liquidated tokens
    uint256 private immutable DURATION; // measure in days. eg 1 days or 7 days
    uint256 private constant ONE_DAY = 1 days;
    uint256 private constant THIRTY_MINUTES = 30 minutes;
    // Streams
    bool private streamsFrozen = false;
    // Liquidator
    mapping(address => Stream) public liqStream;
    // Platform
    mapping(address => Stream) public yieldStream;
    // Batches are for the platformInterest collection
    mapping(address => uint256) public override lastBatchCollected;

    enum StreamType {
        liquidator,
        yield
    }

    struct Stream {
        uint256 end;
        uint256 rate;
    }

    constructor(
        address _nexus,
        address[] memory _mAssets,
        address[] memory _savingsContracts,
        address[] memory _revenueRecipients,
        uint256 _savingsRate,
        uint256 _duration
    ) PausableModule(_nexus) {
        uint256 len = _mAssets.length;
        require(
            _savingsContracts.length == len && _revenueRecipients.length == len,
            "Invalid inputs"
        );
        for (uint256 i = 0; i < len; i++) {
            _updateSavingsContract(_mAssets[i], _savingsContracts[i]);
            emit SavingsContractAdded(_mAssets[i], _savingsContracts[i]);

            revenueRecipients[_mAssets[i]] = IRevenueRecipient(_revenueRecipients[i]);
            emit RevenueRecipientSet(_mAssets[i], _revenueRecipients[i]);
        }
        savingsRate = _savingsRate;
        DURATION = _duration;
    }

    modifier onlyLiquidator() {
        require(msg.sender == _liquidator(), "Only liquidator can execute");
        _;
    }

    modifier whenStreamsNotFrozen() {
        require(!streamsFrozen, "Streaming is currently frozen");
        _;
    }

    /***************************************
                    STATE
    ****************************************/

    /**
     * @dev Adds a new savings contract
     * @param _mAsset           Address of underlying mAsset
     * @param _savingsContract  Address of the savings contract
     */
    function addSavingsContract(address _mAsset, address _savingsContract) external onlyGovernor {
        require(
            address(savingsContracts[_mAsset]) == address(0),
            "Savings contract already exists"
        );
        _updateSavingsContract(_mAsset, _savingsContract);
        emit SavingsContractAdded(_mAsset, _savingsContract);
    }

    /**
     * @dev Updates an existing savings contract
     * @param _mAsset           Address of underlying mAsset
     * @param _savingsContract  Address of the savings contract
     */
    function updateSavingsContract(address _mAsset, address _savingsContract)
        external
        onlyGovernor
    {
        require(
            address(savingsContracts[_mAsset]) != address(0),
            "Savings contract does not exist"
        );
        _updateSavingsContract(_mAsset, _savingsContract);
        emit SavingsContractUpdated(_mAsset, _savingsContract);
    }

    function _updateSavingsContract(address _mAsset, address _savingsContract) internal {
        require(_mAsset != address(0) && _savingsContract != address(0), "Must be valid address");
        savingsContracts[_mAsset] = ISavingsContractV2(_savingsContract);

        IERC20(_mAsset).safeApprove(address(_savingsContract), 0);
        IERC20(_mAsset).safeApprove(address(_savingsContract), type(uint256).max);
    }

    /**
     * @dev Freezes streaming of mAssets
     */
    function freezeStreams() external onlyGovernor whenStreamsNotFrozen {
        streamsFrozen = true;

        emit StreamsFrozen();
    }

    /**
     * @dev Sets the revenue recipient address
     * @param _mAsset           Address of underlying mAsset
     * @param _recipient        Address of the recipient
     */
    function setRevenueRecipient(address _mAsset, address _recipient) external onlyGovernor {
        revenueRecipients[_mAsset] = IRevenueRecipient(_recipient);

        emit RevenueRecipientSet(_mAsset, _recipient);
    }

    /**
     * @dev Sets a new savings rate for interest distribution
     * @param _savingsRate   Rate of savings sent to SavingsContract (100% = 1e18)
     */
    function setSavingsRate(uint256 _savingsRate) external onlyGovernor {
        // Greater than 25% up to 100%
        require(_savingsRate >= 25e16 && _savingsRate <= 1e18, "Must be a valid rate");
        savingsRate = _savingsRate;
        emit SavingsRateChanged(_savingsRate);
    }

    /**
     * @dev Allows the liquidator to deposit proceeds from liquidated gov tokens.
     * Transfers proceeds on a second by second basis to the Savings Contract over 1 week.
     * @param _mAsset The mAsset to transfer and distribute
     * @param _liquidated Units of mAsset to distribute
     */
    function depositLiquidation(address _mAsset, uint256 _liquidated)
        external
        override
        whenNotPaused
        onlyLiquidator
        whenStreamsNotFrozen
    {
        // Collect existing interest to ensure everything is up to date
        _collectAndDistributeInterest(_mAsset);

        // transfer liquidated mUSD to here
        IERC20(_mAsset).safeTransferFrom(_liquidator(), address(this), _liquidated);

        uint256 leftover = _unstreamedRewards(_mAsset, StreamType.liquidator);
        _initialiseStream(_mAsset, StreamType.liquidator, _liquidated + leftover, DURATION);

        emit LiquidatorDeposited(_mAsset, _liquidated);
    }

    /**
     * @dev Collects the platform interest from a given mAsset and then adds capital to the
     * stream. If there is > 24h left in current stream, just top it up, otherwise reset.
     * @param _mAsset The mAsset to fetch interest
     */
    function collectAndStreamInterest(address _mAsset)
        external
        override
        whenNotPaused
        whenStreamsNotFrozen
    {
        // Collect existing interest to ensure everything is up to date
        _collectAndDistributeInterest(_mAsset);

        uint256 currentTime = block.timestamp;
        uint256 previousBatch = lastBatchCollected[_mAsset];
        uint256 timeSincePreviousBatch = currentTime - previousBatch;
        require(timeSincePreviousBatch > 6 hours, "Cannot deposit twice in 6 hours");
        lastBatchCollected[_mAsset] = currentTime;

        // Batch collect
        (uint256 interestCollected, uint256 totalSupply) = IMasset(_mAsset)
        .collectPlatformInterest();

        if (interestCollected > 0) {
            // Validate APY
            uint256 apy = YieldValidator.validateCollection(
                totalSupply,
                interestCollected,
                timeSincePreviousBatch
            );

            // Get remaining rewards
            uint256 leftover = _unstreamedRewards(_mAsset, StreamType.yield);
            _initialiseStream(_mAsset, StreamType.yield, interestCollected + leftover, ONE_DAY);

            emit InterestCollected(_mAsset, interestCollected, totalSupply, apy);
        } else {
            emit InterestCollected(_mAsset, interestCollected, totalSupply, 0);
        }
    }

    /**
     * @dev Calculates how many rewards from the stream are still to be distributed, from the
     * last collection time to the end of the stream.
     * @param _mAsset The mAsset in question
     * @return leftover The total amount of mAsset that is yet to be collected from a stream
     */
    function _unstreamedRewards(address _mAsset, StreamType _stream)
        internal
        view
        returns (uint256 leftover)
    {
        uint256 lastUpdate = lastCollection[_mAsset];

        Stream memory stream = _stream == StreamType.liquidator
            ? liqStream[_mAsset]
            : yieldStream[_mAsset];
        uint256 unclaimedSeconds = 0;
        if (lastUpdate < stream.end) {
            unclaimedSeconds = stream.end - lastUpdate;
        }
        return unclaimedSeconds * stream.rate;
    }

    /**
     * @dev Simply sets up the stream
     * @param _mAsset The mAsset in question
     * @param _amount Amount of units to stream
     * @param _duration Duration of the stream, from now
     */
    function _initialiseStream(
        address _mAsset,
        StreamType _stream,
        uint256 _amount,
        uint256 _duration
    ) internal {
        uint256 currentTime = block.timestamp;
        // Distribute reward per second over X seconds
        uint256 rate = _amount / _duration;
        uint256 end = currentTime + _duration;
        if (_stream == StreamType.liquidator) {
            liqStream[_mAsset] = Stream(end, rate);
        } else {
            yieldStream[_mAsset] = Stream(end, rate);
        }

        // Reset pool data to enable lastCollection usage twice
        require(lastCollection[_mAsset] == currentTime, "Stream data must be up to date");
    }

    /***************************************
                COLLECTION
    ****************************************/

    /**
     * @dev Collects interest from a target mAsset and distributes to the SavingsContract.
     *      Applies constraints such that the max APY since the last fee collection cannot
     *      exceed the "MAX_APY" variable.
     * @param _mAsset       mAsset for which the interest should be collected
     */
    function collectAndDistributeInterest(address _mAsset) external override whenNotPaused {
        _collectAndDistributeInterest(_mAsset);
    }

    function _collectAndDistributeInterest(address _mAsset) internal {
        ISavingsContractV2 savingsContract = savingsContracts[_mAsset];
        require(address(savingsContract) != address(0), "Must have a valid savings contract");

        // Get collection details
        uint256 recentPeriodStart = lastPeriodStart[_mAsset];
        uint256 previousCollection = lastCollection[_mAsset];
        lastCollection[_mAsset] = block.timestamp;

        // 1. Collect the new interest from the mAsset
        IMasset mAsset = IMasset(_mAsset);
        (uint256 interestCollected, uint256 totalSupply) = mAsset.collectInterest();

        // 2. Update all the time stamps
        //    Avoid division by 0 by adding a minimum elapsed time of 1 second
        uint256 timeSincePeriodStart = StableMath.max(1, block.timestamp - recentPeriodStart);
        uint256 timeSinceLastCollection = StableMath.max(1, block.timestamp - previousCollection);

        uint256 inflationOperand = interestCollected;
        //    If it has been 30 mins since last collection, reset period data
        if (timeSinceLastCollection > THIRTY_MINUTES) {
            lastPeriodStart[_mAsset] = block.timestamp;
            periodYield[_mAsset] = 0;
        }
        //    Else if period has elapsed, start a new period from the lastCollection time
        else if (timeSincePeriodStart > THIRTY_MINUTES) {
            lastPeriodStart[_mAsset] = previousCollection;
            periodYield[_mAsset] = interestCollected;
        }
        //    Else add yield to period yield
        else {
            inflationOperand = periodYield[_mAsset] + interestCollected;
            periodYield[_mAsset] = inflationOperand;
        }

        //    Add on liquidated
        uint256 newReward = _unclaimedRewards(_mAsset, previousCollection);
        // 3. Validate that interest is collected correctly and does not exceed max APY
        if (interestCollected > 0 || newReward > 0) {
            require(
                IERC20(_mAsset).balanceOf(address(this)) >= interestCollected + newReward,
                "Must receive mUSD"
            );

            uint256 extrapolatedAPY = YieldValidator.validateCollection(
                totalSupply,
                inflationOperand,
                timeSinceLastCollection
            );

            emit InterestCollected(_mAsset, interestCollected, totalSupply, extrapolatedAPY);

            // 4. Distribute the interest
            //    Calculate the share for savers (95e16 or 95%)
            uint256 saversShare = (interestCollected + newReward).mulTruncate(savingsRate);

            //    Call depositInterest on contract
            savingsContract.depositInterest(saversShare);

            emit InterestDistributed(_mAsset, saversShare);
        } else {
            emit InterestCollected(_mAsset, 0, totalSupply, 0);
        }
    }

    /**
     * @dev Calculates unclaimed rewards from the liquidation stream
     * @param _mAsset mAsset key
     * @param _previousCollection Time of previous collection
     * @return Units of mAsset that have been unlocked for distribution
     */
    function _unclaimedRewards(address _mAsset, uint256 _previousCollection)
        internal
        view
        returns (uint256)
    {
        Stream memory liq = liqStream[_mAsset];
        uint256 unclaimedSeconds_liq = _unclaimedSeconds(_previousCollection, liq.end);
        uint256 subtotal_liq = unclaimedSeconds_liq * liq.rate;

        Stream memory yield = yieldStream[_mAsset];
        uint256 unclaimedSeconds_yield = _unclaimedSeconds(_previousCollection, yield.end);
        uint256 subtotal_yield = unclaimedSeconds_yield * yield.rate;

        return subtotal_liq + subtotal_yield;
    }

    /**
     * @dev Calculates the seconds of unclaimed rewards, based on period length
     * @param _lastUpdate Time of last update
     * @param _end End time of period
     * @return Seconds of stream that should be compensated
     */
    function _unclaimedSeconds(uint256 _lastUpdate, uint256 _end) internal view returns (uint256) {
        uint256 currentTime = block.timestamp;
        uint256 unclaimedSeconds = 0;

        if (currentTime <= _end) {
            unclaimedSeconds = currentTime - _lastUpdate;
        } else if (_lastUpdate < _end) {
            unclaimedSeconds = _end - _lastUpdate;
        }
        return unclaimedSeconds;
    }

    /***************************************
            Revenue Redistribution
    ****************************************/

    /**
     * @dev Redistributes the unallocated interest to the saved recipient, allowing
     * the siphoned assets to be used elsewhere in the system
     * @param _mAsset  mAsset to collect
     */
    function distributeUnallocatedInterest(address _mAsset) external override {
        IRevenueRecipient recipient = revenueRecipients[_mAsset];
        require(address(recipient) != address(0), "Must have valid recipient");

        IERC20 mAsset = IERC20(_mAsset);
        uint256 balance = mAsset.balanceOf(address(this));
        uint256 leftover_liq = _unstreamedRewards(_mAsset, StreamType.liquidator);
        uint256 leftover_yield = _unstreamedRewards(_mAsset, StreamType.yield);

        uint256 unallocated = balance - leftover_liq - leftover_yield;

        mAsset.approve(address(recipient), unallocated);
        recipient.notifyRedistributionAmount(_mAsset, unallocated);

        emit RevenueRedistributed(_mAsset, address(recipient), unallocated);
    }
}

{
  "compilationTarget": {
    "SavingsManager.sol": "SavingsManager"
  },
  "evmVersion": "berlin",
  "libraries": {},
  "metadata": {
    "bytecodeHash": "ipfs"
  },
  "optimizer": {
    "enabled": true,
    "runs": 200
  },
  "remappings": []
}