From 36b007d01ca3d20b009550de9d2fbcb1393e662f Mon Sep 17 00:00:00 2001
From: "mia von steinkirch, phd"
 <1130416+miavonsteinkirch@users.noreply.github.com>
Date: Thu, 17 Nov 2022 12:27:14 -0800
Subject: [PATCH] Create dydx_flahsloan.sol

---
 flashloans/dydx_flahsloan.sol | 61 +++++++++++++++++++++++++++++++++++
 1 file changed, 61 insertions(+)
 create mode 100644 flashloans/dydx_flahsloan.sol

diff --git a/flashloans/dydx_flahsloan.sol b/flashloans/dydx_flahsloan.sol
new file mode 100644
index 0000000..753bf90
--- /dev/null
+++ b/flashloans/dydx_flahsloan.sol
@@ -0,0 +1,61 @@
+function callFunction(address sender, Account.Info memory accountInfo, bytes memory data) external {
+        // Use chi tokens 
+        uint256 gasStart = gasleft();
+
+        // Let the executor or the dYdX contract call this function
+        // probably fine to restrict to dYdX
+        require(msg.sender == executor || msg.sender == address(soloMargin));
+        
+        // Decode the passed variables from the data object
+        (
+            address[] memory sUSDAddresses,
+            uint256[] memory sUSDLoanIDs,
+            uint256 wethEstimate,
+            uint256 usdcEstimate,
+            uint256 ethToCoinbase
+        ) 
+            = abi.decode(data, 
+        (
+            address[],
+            uint256[],
+            uint256,
+            uint256,
+            uint256
+        ));
+
+        // Swap WETH for USDC on uniswap v3
+        uniswapRouter.exactOutputSingle(
+            ISwapRouter.ExactOutputSingleParams(
+                address(WETH),        // address tokenIn;
+                usdcTokenAddress,     // address tokenOut;
+                3000,                 // uint24 fee;
+                address(this),        // address recipient;
+                10**18,               // uint256 deadline;
+                usdcEstimate,         // uint256 amountOut;
+                wethEstimate,         // uint256 amountInMaximum;
+                0                     // uint160 sqrtPriceLimitX96;
+            )
+        );
+
+        // Swap USDC for sUSD on Curve
+        curvePoolSUSD.exchange_underlying(
+            1, // usdc
+            3, // sUSD
+            usdcEstimate, // usdc input
+            1); // min sUSD, generally not advisible to make a trade with a min amount out of 1, but its fine here I think because the overall risk of getting rekt is low
+        
+        // Liquidate the loans
+        for (uint256 i = 0; i < sUSDAddresses.length; i++) {
+            sUSDLoansAddress.liquidateUnclosedLoan(sUSDAddresses[i], sUSDLoanIDs[i]);
+        }
+
+        // We got back ETH but must pay dYdX in WETH, so deposit our whole balance sans what is paid to miners
+        WETH.deposit{value: address(this).balance - ethToCoinbase}();
+
+        // Pay the miner
+        block.coinbase.transfer(ethToCoinbase);
+
+        // Use for chi tokens
+        uint256 gasSpent = 21000 + gasStart - gasleft() + (16 * msg.data.length);
+        CHI.freeFromUpTo(owner, (gasSpent + 14154) / 41947);
+    }