fix: getThawedTokens calculation (TRST-L03)

Author: Maikol

packages/horizon/contracts/staking/HorizonStakingBase.sol

@@ -206,20 +206,25 @@ abstract contract HorizonStakingBase is
             return 0;
         }
 
-        uint256 tokens = 0;
+        uint256 thawedTokens = 0;
         Provision storage prov = _provisions[serviceProvider][verifier];
+        uint256 tokensThawing = prov.tokensThawing;
+        uint256 sharesThawing = prov.sharesThawing;
 
         bytes32 thawRequestId = thawRequestList.head;
         while (thawRequestId != bytes32(0)) {
             ThawRequest storage thawRequest = _getThawRequest(requestType, thawRequestId);
             if (thawRequest.thawingUntil <= block.timestamp) {
-                tokens += (thawRequest.shares * prov.tokensThawing) / prov.sharesThawing;
+                uint256 tokens = (thawRequest.shares * tokensThawing) / sharesThawing;
+                tokensThawing = tokensThawing - tokens;
+                sharesThawing = sharesThawing - thawRequest.shares;
+                thawedTokens = thawedTokens + tokens;
             } else {
                 break;
             }
             thawRequestId = thawRequest.next;
         }
-        return tokens;
+        return thawedTokens;
     }
 
     /**

packages/horizon/test/staking/provision/thaw.t.sol

@@ -139,4 +139,28 @@ contract HorizonStakingThawTest is HorizonStakingTest {
         resetPrank(users.indexer);
         _thaw(users.indexer, subgraphDataServiceAddress, thawAmount);
     }
+
+    function testThaw_GetThawedTokens(
+        uint256 amount,
+        uint64 thawingPeriod,
+        uint256 thawSteps
+    ) public useIndexer useProvision(amount, 0, thawingPeriod) {
+        thawSteps = bound(thawSteps, 1, 10);
+
+        uint256 thawAmount = amount / thawSteps;
+        vm.assume(thawAmount > 0);
+        for (uint256 i = 0; i < thawSteps; i++) {
+            _thaw(users.indexer, subgraphDataServiceAddress, thawAmount);
+        }
+
+        skip(thawingPeriod + 1);
+
+        uint256 thawedTokens = staking.getThawedTokens(
+            ThawRequestType.Provision,
+            users.indexer,
+            subgraphDataServiceAddress,
+            users.indexer
+        );
+        vm.assertEq(thawedTokens, thawAmount * thawSteps);
+    }
 }