// File: contracts/masset/liquidator/Unliquidator.sol



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

import { IClaimRewards } from "../../polygon/IClaimRewards.sol";
import { ImmutableModule } from "../../shared/ImmutableModule.sol";

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

/**
 * @title   Unliquidator
 * @author  mStable
 * @notice  Replacement Contract for the Liquidator.
 *          Does not liquidate the tokens but sends them to the treasury or a set address
 * @dev     VERSION: 1
 *          DATE:    2022-02-10
 */
contract Unliquidator is ImmutableModule {
    using SafeERC20 for IERC20;

    event DistributedRewards(address from, address token, uint256 amount, address to);
    event ReceiverUpdated(address receiver);

    /// @notice Address to which the tokens will be send at the end
    address public receiverSafe;

    constructor(address _nexus, address _receiverSafe) ImmutableModule(_nexus) {
        require(_receiverSafe != address(0), "Invalid receiver address");
        receiverSafe = _receiverSafe;
    }

    /***************************************
                    GOVERNANCE
    ****************************************/

    /**
     * @notice Sets a new receive address for the tokens
     * @param  _receiverSafe  Address to which the tokens will be send at the end
     */

    function setReceiver(address _receiverSafe) external onlyGovernance {
        //
        require(_receiverSafe != address(0), "Invalid receiver address");
        receiverSafe = _receiverSafe;

        emit ReceiverUpdated(_receiverSafe);
    }

    /***************************************
                    CLAIM REWARDS
    ****************************************/

    /**
     * @notice Claims the rewards and sends them to the receiverSafe, e.g. claims and sends stkAave
     * @param  _integration  Integration address, this contract should have permissions to spend the token
     * @param  _token  Address of the token that are claimed and send
     */
    function claimAndDistributeRewards(address _integration, address _token) external {
        //
        require(_integration != address(0), "Invalid integration address");
        require(_token != address(0), "Invalid token address");

        // 1. Claim rewards for the integration contract
        IClaimRewards(_integration).claimRewards();

        // 2. Send token rewards to receiverSafe
        _sendRewards(_integration, _token);
    }

    /**
     * @notice Sends rewards them to the receiverSafe, without claiming them e.g. COMP can be claimed by anyone
     * @param  _integration  Integration address, this contract should have permissions to spend the token
     * @param  _token  Address of the token that are transferred
     */
    function distributeRewards(address _integration, address _token) external {
        require(_integration != address(0), "Invalid integration address");
        require(_token != address(0), "Invalid token address");

        _sendRewards(_integration, _token);
    }

    function _sendRewards(address _from, address _token) internal {
        //
        IERC20 token = IERC20(_token);

        // 1. Get balances of the token
        uint256 amount = token.balanceOf(_from);
        require(amount > 0, "No rewards to send");

        // 2. Send the tokens to the receiverSafe
        SafeERC20.safeTransferFrom(token, _from, receiverSafe, amount);

        // 3. Emit the event
        emit DistributedRewards(_from, _token, amount, receiverSafe);
    }
}

// File: contracts/polygon/IClaimRewards.sol



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

interface IClaimRewards {
    /**
     * @notice claims platform reward tokens from a platform integration.
     * For example, stkAAVE from Aave.
     */
    function claimRewards() external;
}

// 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/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/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;
}

// 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);
            }
        }
    }
}