From 1316cf48e4b605cda20caae6846564906bf0664c Mon Sep 17 00:00:00 2001
From: Hadrien Charlanes <hadrien@variabl.io>
Date: Tue, 6 Apr 2021 15:08:19 +0200
Subject: [PATCH] Updated WETHGateway for withdrawETHWithPermit

---
 contracts/misc/WETHGateway.sol | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/contracts/misc/WETHGateway.sol b/contracts/misc/WETHGateway.sol
index 336e8de2..1ddceaa0 100644
--- a/contracts/misc/WETHGateway.sol
+++ b/contracts/misc/WETHGateway.sol
@@ -131,6 +131,37 @@ contract WETHGateway is IWETHGateway, Ownable {
     _safeTransferETH(msg.sender, amount);
   }
 
+  /**
+   * @dev withdraws the WETH _reserves of msg.sender.
+   * @param lendingPool address of the targeted underlying lending pool
+   * @param amount amount of aWETH to withdraw and receive native ETH
+   * @param to address of the user who will receive native ETH
+   */
+  function withdrawETHWithPermit(
+    address lendingPool,
+    uint256 amount,
+    address to,
+    uint256 deadline,
+    uint8 permitV,
+    bytes32 permitR,
+    bytes32 permitS
+  ) external override {
+    IAToken aWETH = IAToken(ILendingPool(lendingPool).getReserveData(address(WETH)).aTokenAddress);
+    uint256 userBalance = aWETH.balanceOf(msg.sender);
+    uint256 amountToWithdraw = amount;
+
+    // if amount is equal to uint(-1), the user wants to redeem everything
+    if (amount == type(uint256).max) {
+      amountToWithdraw = userBalance;
+    }
+    // chosing to permit `amount`and not `amountToWithdraw`, easier for frontends, intregrators.
+    aWETH.permit(msg.sender, address(this), amount, deadline, permitV, permitR, permitS);
+    aWETH.transferFrom(msg.sender, address(this), amountToWithdraw);
+    ILendingPool(lendingPool).withdraw(address(WETH), amountToWithdraw, address(this));
+    WETH.withdraw(amountToWithdraw);
+    _safeTransferETH(to, amountToWithdraw);
+  }
+
   /**
    * @dev transfer ETH to an address, revert if it fails.
    * @param to recipient of the transfer