Contract

// SPDX-License-Identifier: UNLICENSED
pragma solidity 0.6.12;

import "@openzeppelin/contracts-upgradeable/proxy/Initializable.sol";

import "../external/compound/PriceOracle.sol";
import "../external/compound/CToken.sol";
import "../external/compound/CErc20.sol";

import "./BasePriceOracle.sol";

/**
 * @title MasterPriceOracle
 * @notice Use a combination of price oracles.
 * @dev Implements `PriceOracle`.
 * @author David Lucid <[email protected]> (https://github.com/davidlucid)
 */
contract MasterPriceOracle is Initializable, PriceOracle, BasePriceOracle {
    /**
     * @dev Maps underlying token addresses to `PriceOracle` contracts (can be `BasePriceOracle` contracts too).
     */
    mapping(address => PriceOracle) public oracles;

    /**
     * @dev Default/fallback `PriceOracle`.
     */
    PriceOracle public defaultOracle;

    /**
     * @dev The administrator of this `MasterPriceOracle`.
     */
    address public admin;

    /**
     * @dev Controls if `admin` can overwrite existing assignments of oracles to underlying tokens.
     */
    bool internal noAdminOverwrite;

    /**
     * @dev Returns a boolean indicating if `admin` can overwrite existing assignments of oracles to underlying tokens.
     */
    function canAdminOverwrite() external view returns (bool) {
        return !noAdminOverwrite;
    }

    /**
     * @dev Event emitted when `admin` is changed.
     */
    event NewAdmin(address oldAdmin, address newAdmin);

    /**
     * @dev Event emitted when the default oracle is changed.
     */
    event NewDefaultOracle(address oldOracle, address newOracle);

    /**
     * @dev Event emitted when an underlying token's oracle is changed.
     */
    event NewOracle(address underlying, address oldOracle, address newOracle);

    /**
     * @dev Constructor to initialize state variables.
     * @param underlyings The underlying ERC20 token addresses to link to `_oracles`.
     * @param _oracles The `PriceOracle` contracts to be assigned to `underlyings`.
     * @param _defaultOracle The default `PriceOracle` contract to use.
     * @param _admin The admin who can assign oracles to underlying tokens.
     * @param _canAdminOverwrite Controls if `admin` can overwrite existing assignments of oracles to underlying tokens.
     */
    function initialize(address[] memory underlyings, PriceOracle[] memory _oracles, PriceOracle _defaultOracle, address _admin, bool _canAdminOverwrite) external initializer {
        // Input validation
        require(underlyings.length == _oracles.length, "Lengths of both arrays must be equal.");

        // Initialize state variables
        for (uint256 i = 0; i < underlyings.length; i++) {
            address underlying = underlyings[i];
            PriceOracle newOracle = _oracles[i];
            oracles[underlying] = newOracle;
            emit NewOracle(underlying, address(0), address(newOracle));
        }

        defaultOracle = _defaultOracle;
        admin = _admin;
        noAdminOverwrite = !_canAdminOverwrite;
    }

    /**
     * @dev Sets `_oracles` for `underlyings`.
     */
    function add(address[] calldata underlyings, PriceOracle[] calldata _oracles) external onlyAdmin {
        // Input validation
        require(underlyings.length > 0 && underlyings.length == _oracles.length, "Lengths of both arrays must be equal and greater than 0.");

        // Assign oracles to underlying tokens
        for (uint256 i = 0; i < underlyings.length; i++) {
            address underlying = underlyings[i];
            address oldOracle = address(oracles[underlying]);
            if (noAdminOverwrite) require(oldOracle == address(0), "Admin cannot overwrite existing assignments of oracles to underlying tokens.");
            PriceOracle newOracle = _oracles[i];
            oracles[underlying] = newOracle;
            emit NewOracle(underlying, oldOracle, address(newOracle));
        }
    }

    /**
     * @dev Changes the admin and emits an event.
     */
    function setDefaultOracle(PriceOracle newOracle) external onlyAdmin {
        PriceOracle oldOracle = defaultOracle;
        defaultOracle = newOracle;
        emit NewDefaultOracle(address(oldOracle), address(newOracle));
    }

    /**
     * @dev Changes the admin and emits an event.
     */
    function changeAdmin(address newAdmin) external onlyAdmin {
        address oldAdmin = admin;
        admin = newAdmin;
        emit NewAdmin(oldAdmin, newAdmin);
    }

    /**
     * @dev Modifier that checks if `msg.sender == admin`.
     */
    modifier onlyAdmin {
        require(msg.sender == admin, "Sender is not the admin.");
        _;
    }

    /**
     * @notice Returns the price in ETH of the token underlying `cToken`.
     * @dev Implements the `PriceOracle` interface for Fuse pools (and Compound v2).
     * @return Price in ETH of the token underlying `cToken`, scaled by `10 ** (36 - underlyingDecimals)`.
     */
    function getUnderlyingPrice(CToken cToken) external override view returns (uint) {
        // Get underlying ERC20 token address
        address underlying = address(CErc20(address(cToken)).underlying());

        // Return 1e18 for WETH
        if (underlying == 0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2) return 1e18;

        // Get underlying price from assigned oracle
        PriceOracle oracle = oracles[underlying];
        if (address(oracle) != address(0)) return oracle.getUnderlyingPrice(cToken);
        if (address(defaultOracle) != address(0)) return defaultOracle.getUnderlyingPrice(cToken);
        revert("Price oracle not found for this underlying token address.");
    }

    /**
     * @dev Attempts to return the price in ETH of `underlying` (implements `BasePriceOracle`).
     */
    function price(address underlying) external override view returns (uint) {
        // Return 1e18 for WETH
        if (underlying == 0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2) return 1e18;

        // Get underlying price from assigned oracle
        PriceOracle oracle = oracles[underlying];
        if (address(oracle) != address(0)) return BasePriceOracle(address(oracle)).price(underlying);
        if (address(defaultOracle) != address(0)) return BasePriceOracle(address(defaultOracle)).price(underlying);
        revert("Price oracle not found for this underlying token address.");
    }
}

// SPDX-License-Identifier: MIT

pragma solidity >=0.6.2 <0.8.0;

/**
 * @dev Collection of functions related to the address type
 */
library AddressUpgradeable {
    /**
     * @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;
        // solhint-disable-next-line no-inline-assembly
        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");

        // solhint-disable-next-line avoid-low-level-calls, avoid-call-value
        (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");

        // solhint-disable-next-line avoid-low-level-calls
        (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");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.staticcall(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

                // solhint-disable-next-line no-inline-assembly
                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}

// SPDX-License-Identifier: MIT

// solhint-disable-next-line compiler-version
pragma solidity >=0.4.24 <0.8.0;

import "../utils/AddressUpgradeable.sol";

/**
 * @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 {UpgradeableProxy-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 || _isConstructor() || !_initialized, "Initializable: contract is already initialized");

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

        _;

        if (isTopLevelCall) {
            _initializing = false;
        }
    }

    /// @dev Returns true if and only if the function is running in the constructor
    function _isConstructor() private view returns (bool) {
        return !AddressUpgradeable.isContract(address(this));
    }
}

// SPDX-License-Identifier: UNLICENSED
pragma solidity 0.6.12;

import "../external/compound/PriceOracle.sol";

/**
 * @title BasePriceOracle
 * @notice Returns prices of underlying tokens directly without the caller having to specify a cToken address.
 * @dev Implements the `PriceOracle` interface.
 * @author David Lucid <[email protected]> (https://github.com/davidlucid)
 */
interface BasePriceOracle is PriceOracle {
    /**
     * @notice Get the price of an underlying asset.
     * @param underlying The underlying asset to get the price of.
     * @return The underlying asset price in ETH as a mantissa (scaled by 1e18).
     * Zero means the price is unavailable.
     */
    function price(address underlying) external view returns (uint);
}

// SPDX-License-Identifier: BSD-3-Clause
pragma solidity 0.6.12;

import "./CToken.sol";

interface PriceOracle {
    /**
      * @notice Get the underlying price of a cToken asset
      * @param cToken The cToken to get the underlying price of
      * @return The underlying asset price mantissa (scaled by 1e18).
      *  Zero means the price is unavailable.
      */
    function getUnderlyingPrice(CToken cToken) external view returns (uint);
}

// SPDX-License-Identifier: BSD-3-Clause
pragma solidity 0.6.12;

/**
 * @title Compound's CToken Contract
 * @notice Abstract base for CTokens
 * @author Compound
 */
interface CToken {
    function admin() external view returns (address);
    function adminHasRights() external view returns (bool);
    function fuseAdminHasRights() external view returns (bool);
    function symbol() external view returns (string memory);
    function comptroller() external view returns (address);
    function adminFeeMantissa() external view returns (uint256);
    function fuseFeeMantissa() external view returns (uint256);
    function reserveFactorMantissa() external view returns (uint256);
    function totalReserves() external view returns (uint);
    function totalAdminFees() external view returns (uint);
    function totalFuseFees() external view returns (uint);

    function isCToken() external view returns (bool);
    function isCEther() external view returns (bool);

    function balanceOf(address owner) external view returns (uint);
    function balanceOfUnderlying(address owner) external returns (uint);
    function borrowRatePerBlock() external view returns (uint);
    function supplyRatePerBlock() external view returns (uint);
    function totalBorrowsCurrent() external returns (uint);
    function borrowBalanceStored(address account) external view returns (uint);
    function exchangeRateStored() external view returns (uint);
    function getCash() external view returns (uint);

    function redeem(uint redeemTokens) external returns (uint);
    function redeemUnderlying(uint redeemAmount) external returns (uint);
}

// SPDX-License-Identifier: BSD-3-Clause
pragma solidity 0.6.12;

import "./CToken.sol";

/**
 * @title Compound's CErc20 Contract
 * @notice CTokens which wrap an EIP-20 underlying
 * @author Compound
 */
interface CErc20 is CToken {
    function underlying() external view returns (address);
    function liquidateBorrow(address borrower, uint repayAmount, CToken cTokenCollateral) external returns (uint);
}

{
  "remappings": [],
  "optimizer": {
    "enabled": true,
    "runs": 200
  },
  "evmVersion": "istanbul",
  "libraries": {},
  "outputSelection": {
    "*": {
      "*": [
        "evm.bytecode",
        "evm.deployedBytecode",
        "devdoc",
        "userdoc",
        "metadata",
        "abi"
      ]
    }
  }
}

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