add moonwell oracle and liquidation contract

src/FlashLoanLiquidateMtoken.sol

@@ -0,0 +1,67 @@
+/*
+    Copyright 2022 JOJO Exchange
+    SPDX-License-Identifier: BUSL-1.1
+*/
+
+pragma solidity ^0.8.19;
+
+import "@openzeppelin/contracts/access/Ownable.sol";
+import "@openzeppelin/contracts/token/ERC20/ERC20.sol";
+import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
+import "./interfaces/IJUSDBank.sol";
+import "./interfaces/IJUSDExchange.sol";
+import "./libraries/SignedDecimalMath.sol";
+
+interface MTokenInterface {
+    function redeem(uint redeemTokens) external returns (uint);
+}
+
+contract FlashLoanLiquidateMtoken is Ownable {
+    using SafeERC20 for IERC20;
+    using SignedDecimalMath for uint256;
+
+    address public immutable USDC;
+    address public immutable JUSD;
+    address public jusdBank;
+    address public jusdExchange;
+    address public insurance;
+
+    struct LiquidateData {
+        uint256 actualCollateral;
+        uint256 insuranceFee;
+        uint256 actualLiquidatedT0;
+        uint256 actualLiquidated;
+        uint256 liquidatedRemainUSDC;
+    }
+
+    constructor(address _jusdBank, address _jusdExchange, address _USDC, address _JUSD, address _insurance) {
+        jusdBank = _jusdBank;
+        jusdExchange = _jusdExchange;
+        USDC = _USDC;
+        JUSD = _JUSD;
+        insurance = _insurance;
+    }
+
+    function JOJOFlashLoan(address asset, uint256 amount, address to, bytes calldata param) external {
+        (LiquidateData memory liquidateData, bytes memory originParam) = abi.decode(param, (LiquidateData, bytes));
+        (address liquidator, uint256 minReceive) =
+            abi.decode(originParam, (address, uint256));
+
+        MTokenInterface(asset).redeem(amount);
+        uint256 USDCAmount = IERC20(USDC).balanceOf(address(this));
+        require(USDCAmount >= minReceive, "receive amount is too small");
+        IERC20(USDC).approve(jusdExchange, liquidateData.actualLiquidated);
+        IJUSDExchange(jusdExchange).buyJUSD(liquidateData.actualLiquidated, address(this));
+        IERC20(JUSD).approve(jusdBank, liquidateData.actualLiquidated);
+        IJUSDBank(jusdBank).repay(liquidateData.actualLiquidated, to);
+        IERC20(USDC).safeTransfer(insurance, liquidateData.insuranceFee);
+        if (liquidateData.liquidatedRemainUSDC != 0) {
+            IERC20(USDC).safeTransfer(address(jusdBank), liquidateData.liquidatedRemainUSDC);
+        }
+        IERC20(USDC).safeTransfer(
+            liquidator,
+            USDCAmount - liquidateData.insuranceFee - liquidateData.actualLiquidated
+                - liquidateData.liquidatedRemainUSDC
+        );
+    }
+}

src/oracle/MoonwellOracle.sol

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+/*
+    Copyright 2022 JOJO Exchange
+    SPDX-License-Identifier: BUSL-1.1
+*/
+
+pragma solidity ^0.8.19;
+
+import "@openzeppelin/contracts/access/Ownable.sol";
+import "@openzeppelin/contracts/utils/math/SafeCast.sol";
+
+interface MTokenInterface {
+    function exchangeRateStored() external view returns (uint);
+}
+
+contract MoonwellOracle {
+    uint256 public price;
+    address public immutable source;
+    string public description;
+
+    constructor(string memory _description, address _source) {
+        description = _description;
+        source = _source;
+    }
+
+    function getAssetPrice() external view returns (uint256) {
+        uint256 rate = MTokenInterface(source).exchangeRateStored();
+        return rate;
+    }
+}