From 6dbb9cd4e1360a70d593167dc7d371b686612b93 Mon Sep 17 00:00:00 2001
From: Domen Grabec <grabec@gmail.com>
Date: Thu, 7 Dec 2023 00:44:48 +0100
Subject: [PATCH] rename variable, add test for double withdrawal. Gas
 optimisation when withdrawingAll with no BPT

---
 .../balancer/BalancerMetaPoolStrategy.sol        | 16 +++++++++++-----
 .../balancerMetaStablePool.fork-test.js          |  9 +++++++++
 2 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/contracts/contracts/strategies/balancer/BalancerMetaPoolStrategy.sol b/contracts/contracts/strategies/balancer/BalancerMetaPoolStrategy.sol
index 82e81ab883..9e7ec13847 100644
--- a/contracts/contracts/strategies/balancer/BalancerMetaPoolStrategy.sol
+++ b/contracts/contracts/strategies/balancer/BalancerMetaPoolStrategy.sol
@@ -174,11 +174,11 @@ contract BalancerMetaPoolStrategy is BaseAuraStrategy {
             }
         }
 
-        uint256 minBPT = _getBPTExpected(
+        uint256 minBpt = _getBPTExpected(
             strategyAssetsToPoolAssets,
             strategyAssetAmountsToPoolAssetAmounts
         );
-        uint256 minBPTwDeviation = minBPT.mulTruncate(
+        uint256 minBptWDeviation = minBpt.mulTruncate(
             1e18 - maxDepositDeviation
         );
 
@@ -192,7 +192,7 @@ contract BalancerMetaPoolStrategy is BaseAuraStrategy {
         bytes memory userData = abi.encode(
             IBalancerVault.MetaStablePoolJoinKind.EXACT_TOKENS_IN_FOR_BPT_OUT,
             _getUserDataEncodedAmounts(amountsIn),
-            minBPTwDeviation
+            minBptWDeviation
         );
 
         IBalancerVault.JoinPoolRequest memory request = IBalancerVault
@@ -471,9 +471,15 @@ contract BalancerMetaPoolStrategy is BaseAuraStrategy {
         // STEP 1 - Withdraw all Balancer Pool Tokens (BPT) from Aura to this strategy contract
         _lpWithdrawAll();
         // Get the BPTs withdrawn from Aura plus any that were already in this strategy contract
-        uint256 BPTtoWithdraw = IERC20(platformAddress).balanceOf(
+        uint256 bptToWithdraw = IERC20(platformAddress).balanceOf(
             address(this)
         );
+
+        // Do not proceed with withdrawal if there is nothing to withdraw
+        if (bptToWithdraw == 0) {
+            return;
+        }
+
         uint256[] memory minAmountsOut = new uint256[](_poolAssets.length);
 
         // STEP 2 - Withdraw the Balancer pool assets from the pool
@@ -495,7 +501,7 @@ contract BalancerMetaPoolStrategy is BaseAuraStrategy {
             isRecoveryModeWithdrawal
                 ? RECOVERY_MODE_EXIT_KIND
                 : _exactBptInTokensOutIndex(),
-            BPTtoWithdraw
+            bptToWithdraw
         );
 
         if (isRecoveryModeWithdrawal) {
diff --git a/contracts/test/strategies/balancerMetaStablePool.fork-test.js b/contracts/test/strategies/balancerMetaStablePool.fork-test.js
index b7451ea6bc..93d13d7298 100644
--- a/contracts/test/strategies/balancerMetaStablePool.fork-test.js
+++ b/contracts/test/strategies/balancerMetaStablePool.fork-test.js
@@ -1055,6 +1055,15 @@ describe("ForkTest: Balancer MetaStablePool wstETH/WETH Strategy", function () {
       expect(wethBalanceDiff).to.be.gte(await units("15", weth), 1);
       expect(stEthBalanceDiff).to.be.gte(await units("15", stETH), 1);
     });
+
+    it("Should be able to call withdrawAll twice (second time musn't revert)", async function () {
+      const { oethVault, balancerWstEthStrategy } = fixture;
+
+      const oethVaultSigner = await impersonateAndFund(oethVault.address);
+
+      await balancerWstEthStrategy.connect(oethVaultSigner).withdrawAll();
+      await balancerWstEthStrategy.connect(oethVaultSigner).withdrawAll();
+    });
   });
 
   describe("Harvest rewards", function () {