factor duplicated approval/permit2 code

Author: hoytech

src/EulerSwap.sol

@@ -164,24 +164,21 @@ contract EulerSwap is IEulerSwap, EVCUtil {
         require(status != 2, Locked());
         status = 1;
 
-        address permit2 = IEVault(vault0).permit2Address();
-        if (permit2 == address(0)) {
-            IERC20(asset0).forceApprove(vault0, type(uint256).max);
-        } else {
-            IERC20(asset0).forceApprove(permit2, type(uint256).max);
-            IAllowanceTransfer(permit2).approve(asset0, vault0, type(uint160).max, type(uint48).max);
-        }
+        approveVault(asset0, vault0);
+        approveVault(asset1, vault1);
+
+        IEVC(evc).enableCollateral(eulerAccount, vault0);
+        IEVC(evc).enableCollateral(eulerAccount, vault1);
+    }
 
-        permit2 = IEVault(vault1).permit2Address();
+    function approveVault(address asset, address vault) internal {
+        address permit2 = IEVault(vault).permit2Address();
         if (permit2 == address(0)) {
-            IERC20(asset1).forceApprove(vault1, type(uint256).max);
+            IERC20(asset).forceApprove(vault, type(uint256).max);
         } else {
-            IERC20(asset1).forceApprove(permit2, type(uint256).max);
-            IAllowanceTransfer(permit2).approve(asset1, vault1, type(uint160).max, type(uint48).max);
+            IERC20(asset).forceApprove(permit2, type(uint256).max);
+            IAllowanceTransfer(permit2).approve(asset, vault, type(uint160).max, type(uint48).max);
         }
-
-        IEVC(evc).enableCollateral(eulerAccount, vault0);
-        IEVC(evc).enableCollateral(eulerAccount, vault1);
     }
 
     /// @inheritdoc IEulerSwap