// File: contracts/polygon/PAaveIntegration.sol



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

import { IAaveATokenV2, IAaveLendingPoolV2, ILendingPoolAddressesProviderV2 } from "../peripheral/Aave/IAave.sol";
import { AaveV2Integration } from "../masset/peripheral/AaveV2Integration.sol";
import { IAaveIncentivesController } from "../peripheral/Aave/IAaveIncentivesController.sol";

/**
 * @title   PAaveIntegration
 * @author  mStable
 * @notice  A simple connection to deposit and withdraw bAssets from Aave on Polygon
 * @dev     VERSION: 1.0
 *          DATE:    2020-16-11
 */
contract PAaveIntegration is AaveV2Integration {
    event RewardsClaimed(address[] assets, uint256 amount);

    IAaveIncentivesController public immutable rewardController;

    /**
     * @param _nexus            Address of the Nexus
     * @param _lp               Address of LP
     * @param _platformAddress  Generic platform address
     * @param _rewardToken      Reward token, if any
     * @param _rewardController AaveIncentivesController
     */
    constructor(
        address _nexus,
        address _lp,
        address _platformAddress,
        address _rewardToken,
        address _rewardController
    ) AaveV2Integration(_nexus, _lp, _platformAddress, _rewardToken) {
        require(_rewardController != address(0), "Invalid controller address");

        rewardController = IAaveIncentivesController(_rewardController);
    }

    /**
     * @dev Claims outstanding rewards from market
     */
    function claimRewards() external {
        uint256 len = bAssetsMapped.length;
        address[] memory pTokens = new address[](len);
        for (uint256 i = 0; i < len; i++) {
            pTokens[i] = bAssetToPToken[bAssetsMapped[i]];
        }
        uint256 rewards = rewardController.claimRewards(pTokens, type(uint256).max, address(this));

        emit RewardsClaimed(pTokens, rewards);
    }
}

// File: contracts/peripheral/Aave/IAave.sol



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

/**
 * @dev Interface for Aaves Lending Pool
 * Documentation: https://developers.aave.com/#lendingpooladdressesprovider
 */
interface ILendingPoolAddressesProviderV2 {
    /**
     * @notice Get the current address for Aave LendingPool
     * @dev Lending pool is the core contract on which to call deposit
     */
    function getLendingPool() external view returns (address);
}

/**
 * @dev Interface for Aaves A Token
 * Documentation: https://developers.aave.com/#atokens
 */
interface IAaveATokenV2 {
    /**
     * @notice returns the current total aToken balance of _user all interest collected included.
     * To obtain the user asset principal balance with interests excluded , ERC20 non-standard
     * method principalBalanceOf() can be used.
     */
    function balanceOf(address _user) external view returns (uint256);
}

interface IAaveLendingPoolV2 {
    /**
     * @dev deposits The underlying asset into the reserve. A corresponding amount of the overlying asset (aTokens)
     * is minted.
     * @param reserve the address of the reserve
     * @param amount the amount to be deposited
     * @param referralCode integrators are assigned a referral code and can potentially receive rewards.
     **/
    function deposit(
        address reserve,
        uint256 amount,
        address onBehalfOf,
        uint16 referralCode
    ) external;

    /**
     * @dev withdraws the assets of user.
     * @param reserve the address of the reserve
     * @param amount the underlying amount to be redeemed
     * @param to address that will receive the underlying
     **/
    function withdraw(
        address reserve,
        uint256 amount,
        address to
    ) external;
}

/** Interface for Staking AAVE Token
 * Documentation: https://docs.aave.com/developers/protocol-governance/staking-aave
 */
interface IStakedAave {
    function COOLDOWN_SECONDS() external returns (uint256);

    function UNSTAKE_WINDOW() external returns (uint256);

    function stake(address to, uint256 amount) external;

    function redeem(address to, uint256 amount) external;

    function cooldown() external;

    function claimRewards(address to, uint256 amount) external;

    function stakersCooldowns(address staker) external returns (uint256);
}

// File: contracts/masset/peripheral/AaveV2Integration.sol



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

// External
import { IAaveATokenV2, IAaveLendingPoolV2, ILendingPoolAddressesProviderV2 } from "../../peripheral/Aave/IAave.sol";

// Libs
import { MassetHelpers } from "../../shared/MassetHelpers.sol";
import { SafeERC20 } from "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
import { IERC20 } from "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import { AbstractIntegration } from "./AbstractIntegration.sol";

/**
 * @title   AaveV2Integration
 * @author  mStable
 * @notice  A simple connection to deposit and withdraw bAssets from Aave
 * @dev     VERSION: 1.0
 *          DATE:    2020-16-11
 */
contract AaveV2Integration is AbstractIntegration {
    using SafeERC20 for IERC20;

    // Core address for the given platform */
    address public immutable platformAddress;
    address public immutable rewardToken;

    event RewardTokenApproved(address rewardToken, address account);

    /**
     * @param _nexus            Address of the Nexus
     * @param _lp               Address of LP
     * @param _platformAddress  Generic platform address
     * @param _rewardToken      Reward token, if any
     */
    constructor(
        address _nexus,
        address _lp,
        address _platformAddress,
        address _rewardToken
    ) AbstractIntegration(_nexus, _lp) {
        require(_platformAddress != address(0), "Invalid platform address");

        platformAddress = _platformAddress;

        rewardToken = _rewardToken;
    }

    /***************************************
                    ADMIN
    ****************************************/

    /**
     * @dev Approves Liquidator to spend reward tokens
     */
    function approveRewardToken() external onlyGovernor {
        address liquidator = nexus.getModule(keccak256("Liquidator"));
        require(liquidator != address(0), "Liquidator address cannot be zero");

        MassetHelpers.safeInfiniteApprove(rewardToken, liquidator);

        emit RewardTokenApproved(rewardToken, liquidator);
    }

    /***************************************
                    CORE
    ****************************************/

    /**
     * @dev Deposit a quantity of bAsset into the platform. Credited aTokens
     *      remain here in the vault. Can only be called by whitelisted addresses
     *      (mAsset and corresponding BasketManager)
     * @param _bAsset              Address for the bAsset
     * @param _amount              Units of bAsset to deposit
     * @param _hasTxFee            Is the bAsset known to have a tx fee?
     * @return quantityDeposited   Quantity of bAsset that entered the platform
     */
    function deposit(
        address _bAsset,
        uint256 _amount,
        bool _hasTxFee
    ) external override onlyLP nonReentrant returns (uint256 quantityDeposited) {
        require(_amount > 0, "Must deposit something");

        IAaveATokenV2 aToken = _getATokenFor(_bAsset);

        quantityDeposited = _amount;

        if (_hasTxFee) {
            // If we charge a fee, account for it
            uint256 prevBal = _checkBalance(aToken);
            _getLendingPool().deposit(_bAsset, _amount, address(this), 36);
            uint256 newBal = _checkBalance(aToken);
            quantityDeposited = _min(quantityDeposited, newBal - prevBal);
        } else {
            _getLendingPool().deposit(_bAsset, _amount, address(this), 36);
        }

        emit Deposit(_bAsset, address(aToken), quantityDeposited);
    }

    /**
     * @dev Withdraw a quantity of bAsset from the platform
     * @param _receiver     Address to which the bAsset should be sent
     * @param _bAsset       Address of the bAsset
     * @param _amount       Units of bAsset to withdraw
     * @param _hasTxFee     Is the bAsset known to have a tx fee?
     */
    function withdraw(
        address _receiver,
        address _bAsset,
        uint256 _amount,
        bool _hasTxFee
    ) external override onlyLP nonReentrant {
        _withdraw(_receiver, _bAsset, _amount, _amount, _hasTxFee);
    }

    /**
     * @dev Withdraw a quantity of bAsset from the platform
     * @param _receiver     Address to which the bAsset should be sent
     * @param _bAsset       Address of the bAsset
     * @param _amount       Units of bAsset to send to recipient
     * @param _totalAmount  Total units to pull from lending platform
     * @param _hasTxFee     Is the bAsset known to have a tx fee?
     */
    function withdraw(
        address _receiver,
        address _bAsset,
        uint256 _amount,
        uint256 _totalAmount,
        bool _hasTxFee
    ) external override onlyLP nonReentrant {
        _withdraw(_receiver, _bAsset, _amount, _totalAmount, _hasTxFee);
    }

    /** @dev Withdraws _totalAmount from the lending pool, sending _amount to user */
    function _withdraw(
        address _receiver,
        address _bAsset,
        uint256 _amount,
        uint256 _totalAmount,
        bool _hasTxFee
    ) internal {
        require(_totalAmount > 0, "Must withdraw something");

        IAaveATokenV2 aToken = _getATokenFor(_bAsset);

        if (_hasTxFee) {
            require(_amount == _totalAmount, "Cache inactive for assets with fee");
            _getLendingPool().withdraw(_bAsset, _amount, _receiver);
        } else {
            _getLendingPool().withdraw(_bAsset, _totalAmount, address(this));
            // Send redeemed bAsset to the receiver
            IERC20(_bAsset).safeTransfer(_receiver, _amount);
        }

        emit PlatformWithdrawal(_bAsset, address(aToken), _totalAmount, _amount);
    }

    /**
     * @dev Withdraw a quantity of bAsset from the cache.
     * @param _receiver     Address to which the bAsset should be sent
     * @param _bAsset       Address of the bAsset
     * @param _amount       Units of bAsset to withdraw
     */
    function withdrawRaw(
        address _receiver,
        address _bAsset,
        uint256 _amount
    ) external override onlyLP nonReentrant {
        require(_amount > 0, "Must withdraw something");
        require(_receiver != address(0), "Must specify recipient");

        IERC20(_bAsset).safeTransfer(_receiver, _amount);

        emit Withdrawal(_bAsset, address(0), _amount);
    }

    /**
     * @dev Get the total bAsset value held in the platform
     *      This includes any interest that was generated since depositing
     *      Aave gradually increases the balances of all aToken holders, as the interest grows
     * @param _bAsset     Address of the bAsset
     * @return balance    Total value of the bAsset in the platform
     */
    function checkBalance(address _bAsset) external view override returns (uint256 balance) {
        // balance is always with token aToken decimals
        IAaveATokenV2 aToken = _getATokenFor(_bAsset);
        return _checkBalance(aToken);
    }

    /***************************************
                    APPROVALS
    ****************************************/

    /**
     * @dev Internal method to respond to the addition of new bAsset / pTokens
     *      We need to approve the Aave lending pool core conrtact and give it permission
     *      to spend the bAsset
     * @param _bAsset Address of the bAsset to approve
     */
    function _abstractSetPToken(
        address _bAsset,
        address /*_pToken*/
    ) internal override {
        address lendingPool = address(_getLendingPool());
        // approve the pool to spend the bAsset
        MassetHelpers.safeInfiniteApprove(_bAsset, lendingPool);
    }

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

    /**
     * @dev Get the current address of the Aave lending pool, which is the gateway to
     *      depositing.
     * @return Current lending pool implementation
     */
    function _getLendingPool() internal view returns (IAaveLendingPoolV2) {
        address lendingPool = ILendingPoolAddressesProviderV2(platformAddress).getLendingPool();
        require(lendingPool != address(0), "Lending pool does not exist");
        return IAaveLendingPoolV2(lendingPool);
    }

    /**
     * @dev Get the pToken wrapped in the IAaveAToken interface for this bAsset, to use
     *      for withdrawing or balance checking. Fails if the pToken doesn't exist in our mappings.
     * @param _bAsset  Address of the bAsset
     * @return aToken  Corresponding to this bAsset
     */
    function _getATokenFor(address _bAsset) internal view returns (IAaveATokenV2) {
        address aToken = bAssetToPToken[_bAsset];
        require(aToken != address(0), "aToken does not exist");
        return IAaveATokenV2(aToken);
    }

    /**
     * @dev Get the total bAsset value held in the platform
     * @param _aToken     aToken for which to check balance
     * @return balance    Total value of the bAsset in the platform
     */
    function _checkBalance(IAaveATokenV2 _aToken) internal view returns (uint256 balance) {
        return _aToken.balanceOf(address(this));
    }
}

// File: contracts/peripheral/Aave/IAaveIncentivesController.sol



// SPDX-License-Identifier: agpl-3.0
pragma solidity 0.8.6;
pragma experimental ABIEncoderV2;

interface IAaveIncentivesController {
    /**
     * @dev Claims reward for an user, on all the assets of the lending pool, accumulating the pending rewards
     * @param amount Amount of rewards to claim
     * @param to Address that will be receiving the rewards
     * @return Rewards claimed
     **/
    function claimRewards(
        address[] calldata assets,
        uint256 amount,
        address to
    ) external returns (uint256);

    /**
     * @dev Returns the total of rewards of an user, already accrued + not yet accrued
     * @param user The address of the user
     * @return The rewards
     **/
    function getRewardsBalance(address[] calldata assets, address user)
        external
        view
        returns (uint256);

    /**
     * @dev returns the unclaimed rewards of the user
     * @param user the address of the user
     * @return the unclaimed user rewards
     */
    function getUserUnclaimedRewards(address user) external view returns (uint256);
}

// File: contracts/shared/MassetHelpers.sol



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

import { SafeERC20 } from "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
import { IERC20 } from "@openzeppelin/contracts/token/ERC20/IERC20.sol";

/**
 * @title   MassetHelpers
 * @author  mStable
 * @notice  Helper functions to facilitate minting and redemption from off chain
 * @dev     VERSION: 1.0
 *          DATE:    2020-03-28
 */
library MassetHelpers {
    using SafeERC20 for IERC20;

    function transferReturnBalance(
        address _sender,
        address _recipient,
        address _bAsset,
        uint256 _qty
    ) internal returns (uint256 receivedQty, uint256 recipientBalance) {
        uint256 balBefore = IERC20(_bAsset).balanceOf(_recipient);
        IERC20(_bAsset).safeTransferFrom(_sender, _recipient, _qty);
        recipientBalance = IERC20(_bAsset).balanceOf(_recipient);
        receivedQty = recipientBalance - balBefore;
    }

    function safeInfiniteApprove(address _asset, address _spender) internal {
        IERC20(_asset).safeApprove(_spender, 0);
        IERC20(_asset).safeApprove(_spender, 2**256 - 1);
    }
}

// File: @openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "../IERC20.sol";
import "../../../utils/Address.sol";

/**
 * @title SafeERC20
 * @dev Wrappers around ERC20 operations that throw on failure (when the token
 * contract returns false). Tokens that return no value (and instead revert or
 * throw on failure) are also supported, non-reverting calls are assumed to be
 * successful.
 * To use this library you can add a `using SafeERC20 for IERC20;` statement to your contract,
 * which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
 */
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");
        }
    }
}

// File: @openzeppelin/contracts/token/ERC20/IERC20.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
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);
}

// File: contracts/masset/peripheral/AbstractIntegration.sol



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

import { IPlatformIntegration } from "../../interfaces/IPlatformIntegration.sol";
import { ImmutableModule } from "../../shared/ImmutableModule.sol";
import { ReentrancyGuard } from "@openzeppelin/contracts/security/ReentrancyGuard.sol";
import { Initializable } from "@openzeppelin/contracts/proxy/utils/Initializable.sol";

/**
 * @title   AbstractIntegration
 * @author  mStable
 * @notice  A generalised platform integration contract from which to inherit
 * @dev     Contains functionality for managing access to a specific lending
 *          platform. pTokens are the generic name given to platform tokens e.g. cDai
 *          Governance are responsible for setting platform and pToken addresses.
 */
abstract contract AbstractIntegration is
    IPlatformIntegration,
    Initializable,
    ImmutableModule,
    ReentrancyGuard
{
    event PTokenAdded(address indexed _bAsset, address _pToken);

    event Deposit(address indexed _bAsset, address _pToken, uint256 _amount);
    event Withdrawal(address indexed _bAsset, address _pToken, uint256 _amount);
    event PlatformWithdrawal(
        address indexed bAsset,
        address pToken,
        uint256 totalAmount,
        uint256 userAmount
    );

    /// @notice mAsset or Feeder Pool using the integration. eg fPmUSD/alUSD
    /// @dev LP has write access
    address public immutable lpAddress;

    // bAsset => pToken (Platform Specific Token Address)
    mapping(address => address) public bAssetToPToken;
    // Full list of all bAssets supported here
    address[] internal bAssetsMapped;

    /**
     * @param _nexus     Address of the Nexus
     * @param _lp        Address of LP
     */
    constructor(address _nexus, address _lp) ReentrancyGuard() ImmutableModule(_nexus) {
        require(_lp != address(0), "Invalid LP address");
        lpAddress = _lp;
    }

    /**
     * @dev Simple initializer to set first bAsset/pTokens
     */
    function initialize(address[] calldata _bAssets, address[] calldata _pTokens)
        public
        initializer
    {
        uint256 len = _bAssets.length;
        require(len == _pTokens.length, "Invalid inputs");
        for (uint256 i = 0; i < len; i++) {
            _setPTokenAddress(_bAssets[i], _pTokens[i]);
        }
    }

    /**
     * @dev Modifier to allow function calls only from the Governor.
     */
    modifier onlyLP() {
        require(msg.sender == lpAddress, "Only the LP can execute");
        _;
    }

    /***************************************
                    CONFIG
    ****************************************/

    /**
     * @dev Provide support for bAsset by passing its pToken address.
     * This method can only be called by the system Governor
     * @param _bAsset   Address for the bAsset
     * @param _pToken   Address for the corresponding platform token
     */
    function setPTokenAddress(address _bAsset, address _pToken) external onlyGovernor {
        _setPTokenAddress(_bAsset, _pToken);
    }

    /**
     * @dev Provide support for bAsset by passing its pToken address.
     * Add to internal mappings and execute the platform specific,
     * abstract method `_abstractSetPToken`
     * @param _bAsset   Address for the bAsset
     * @param _pToken   Address for the corresponding platform token
     */
    function _setPTokenAddress(address _bAsset, address _pToken) internal {
        require(bAssetToPToken[_bAsset] == address(0), "pToken already set");
        require(_bAsset != address(0) && _pToken != address(0), "Invalid addresses");

        bAssetToPToken[_bAsset] = _pToken;
        bAssetsMapped.push(_bAsset);

        emit PTokenAdded(_bAsset, _pToken);

        _abstractSetPToken(_bAsset, _pToken);
    }

    function _abstractSetPToken(address _bAsset, address _pToken) internal virtual;

    /**
     * @dev Simple helper func to get the min of two values
     */
    function _min(uint256 x, uint256 y) internal pure returns (uint256) {
        return x > y ? y : x;
    }
}

// File: @openzeppelin/contracts/utils/Address.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @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);
    }

    /**
     * @dev Tool to verifies that a low level call was successful, and revert if it wasn't, either by bubbling the
     * revert reason using the provided one.
     *
     * _Available since v4.3._
     */
    function verifyCallResult(
        bool success,
        bytes memory returndata,
        string memory errorMessage
    ) internal 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);
            }
        }
    }
}

// File: contracts/interfaces/IPlatformIntegration.sol



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

/**
 * @title Platform interface to integrate with lending platform like Compound, AAVE etc.
 */
interface IPlatformIntegration {
    /**
     * @dev Deposit the given bAsset to Lending platform
     * @param _bAsset bAsset address
     * @param _amount Amount to deposit
     */
    function deposit(
        address _bAsset,
        uint256 _amount,
        bool isTokenFeeCharged
    ) external returns (uint256 quantityDeposited);

    /**
     * @dev Withdraw given bAsset from Lending platform
     */
    function withdraw(
        address _receiver,
        address _bAsset,
        uint256 _amount,
        bool _hasTxFee
    ) external;

    /**
     * @dev Withdraw given bAsset from Lending platform
     */
    function withdraw(
        address _receiver,
        address _bAsset,
        uint256 _amount,
        uint256 _totalAmount,
        bool _hasTxFee
    ) external;

    /**
     * @dev Withdraw given bAsset from the cache
     */
    function withdrawRaw(
        address _receiver,
        address _bAsset,
        uint256 _amount
    ) external;

    /**
     * @dev Returns the current balance of the given bAsset
     */
    function checkBalance(address _bAsset) external returns (uint256 balance);
}

// File: contracts/shared/ImmutableModule.sol



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

import { ModuleKeys } from "./ModuleKeys.sol";
import { INexus } from "../interfaces/INexus.sol";

/**
 * @title   ImmutableModule
 * @author  mStable
 * @dev     Subscribes to module updates from a given publisher and reads from its registry.
 *          Contract is used for upgradable proxy contracts.
 */
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 Governor or the Keeper EOA.
     */
    modifier onlyKeeperOrGovernor() {
        _keeperOrGovernor();
        _;
    }

    function _keeperOrGovernor() internal view {
        require(msg.sender == _keeper() || msg.sender == _governor(), "Only keeper or governor");
    }

    /**
     * @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 Keeper address from the Nexus.
     *      This account is used for operational transactions that
     *      don't need multiple signatures.
     * @return  Address of the Keeper externally owned account.
     */
    function _keeper() internal view returns (address) {
        return nexus.getModule(KEY_KEEPER);
    }

    /**
     * @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);
    }
}

// File: @openzeppelin/contracts/security/ReentrancyGuard.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @dev Contract module that helps prevent reentrant calls to a function.
 *
 * Inheriting from `ReentrancyGuard` will make the {nonReentrant} modifier
 * available, which can be applied to functions to make sure there are no nested
 * (reentrant) calls to them.
 *
 * Note that because there is a single `nonReentrant` guard, functions marked as
 * `nonReentrant` may not call one another. This can be worked around by making
 * those functions `private`, and then adding `external` `nonReentrant` entry
 * points to them.
 *
 * TIP: If you would like to learn more about reentrancy and alternative ways
 * to protect against it, check out our blog post
 * https://blog.openzeppelin.com/reentrancy-after-istanbul/[Reentrancy After Istanbul].
 */
abstract contract ReentrancyGuard {
    // Booleans are more expensive than uint256 or any type that takes up a full
    // word because each write operation emits an extra SLOAD to first read the
    // slot's contents, replace the bits taken up by the boolean, and then write
    // back. This is the compiler's defense against contract upgrades and
    // pointer aliasing, and it cannot be disabled.

    // The values being non-zero value makes deployment a bit more expensive,
    // but in exchange the refund on every call to nonReentrant will be lower in
    // amount. Since refunds are capped to a percentage of the total
    // transaction's gas, it is best to keep them low in cases like this one, to
    // increase the likelihood of the full refund coming into effect.
    uint256 private constant _NOT_ENTERED = 1;
    uint256 private constant _ENTERED = 2;

    uint256 private _status;

    constructor() {
        _status = _NOT_ENTERED;
    }

    /**
     * @dev Prevents a contract from calling itself, directly or indirectly.
     * Calling a `nonReentrant` function from another `nonReentrant`
     * function is not supported. It is possible to prevent this from happening
     * by making the `nonReentrant` function external, and make it call a
     * `private` function that does the actual work.
     */
    modifier nonReentrant() {
        // On the first call to nonReentrant, _notEntered will be true
        require(_status != _ENTERED, "ReentrancyGuard: reentrant call");

        // Any calls to nonReentrant after this point will fail
        _status = _ENTERED;

        _;

        // By storing the original value once again, a refund is triggered (see
        // https://eips.ethereum.org/EIPS/eip-2200)
        _status = _NOT_ENTERED;
    }
}

// File: @openzeppelin/contracts/proxy/utils/Initializable.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @dev This is a base contract to aid in writing upgradeable contracts, or any kind of contract that will be deployed
 * behind a proxy. Since a proxied contract can't have a constructor, it's common to move constructor logic to an
 * external initializer function, usually called `initialize`. It then becomes necessary to protect this initializer
 * function so it can only be called once. The {initializer} modifier provided by this contract will have this effect.
 *
 * TIP: To avoid leaving the proxy in an uninitialized state, the initializer function should be called as early as
 * possible by providing the encoded function call as the `_data` argument to {ERC1967Proxy-constructor}.
 *
 * CAUTION: When used with inheritance, manual care must be taken to not invoke a parent initializer twice, or to ensure
 * that all initializers are idempotent. This is not verified automatically as constructors are by Solidity.
 */
abstract contract Initializable {
    /**
     * @dev Indicates that the contract has been initialized.
     */
    bool private _initialized;

    /**
     * @dev Indicates that the contract is in the process of being initialized.
     */
    bool private _initializing;

    /**
     * @dev Modifier to protect an initializer function from being invoked twice.
     */
    modifier initializer() {
        require(_initializing || !_initialized, "Initializable: contract is already initialized");

        bool isTopLevelCall = !_initializing;
        if (isTopLevelCall) {
            _initializing = true;
            _initialized = true;
        }

        _;

        if (isTopLevelCall) {
            _initializing = false;
        }
    }
}

// File: contracts/shared/ModuleKeys.sol



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

/**
 * @title  ModuleKeys
 * @author mStable
 * @notice Provides system wide access to the byte32 represntations of system modules
 *         This allows each system module to be able to reference and update one another in a
 *         friendly way
 * @dev    keccak256() values are hardcoded to avoid re-evaluation of the constants at runtime.
 */
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;
    // keccak256("Keeper");
    bytes32 internal constant KEY_KEEPER =
        0x4f78afe9dfc9a0cb0441c27b9405070cd2a48b490636a7bdd09f355e33a5d7de;
}

// File: contracts/interfaces/INexus.sol



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

/**
 * @title INexus
 * @dev Basic interface for interacting with the Nexus i.e. SystemKernel
 */
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;
}