fix: use zeroFloorPlus to compute totalBorrowAssets

src/distribute-market-rewards.ts

@@ -4,7 +4,7 @@ import { MorphoTx } from "../generated/schema";
 
 import { getMarket, setupPosition } from "./initializers";
 import { snapshotMarket, snapshotPosition } from "./snapshots";
-import { EventType } from "./utils";
+import { EventType, zeroFloorPlus } from "./utils";
 
 export function computeMarketPoints(marketId: Bytes, timestamp: BigInt): void {
   const market = getMarket(marketId);
@@ -72,7 +72,11 @@ export function handleMorphoTx(morphoTx: MorphoTx): void {
   } else if (morphoTx.type === EventType.BORROW) {
     position.borrowShares = position.borrowShares.plus(morphoTx.shares);
     market.totalBorrowShares = market.totalBorrowShares.plus(morphoTx.shares);
-    market.totalBorrowAssets = market.totalBorrowAssets.plus(morphoTx.assets);
+    // zeroFloorPlus to avoid negative values when the user repays or get liquidated
+    market.totalBorrowAssets = zeroFloorPlus(
+      market.totalBorrowAssets,
+      morphoTx.assets
+    );
   } else if (morphoTx.type === EventType.COLLATERAL) {
     position.collateral = position.collateral.plus(morphoTx.assets);
     market.totalCollateral = market.totalCollateral.plus(morphoTx.assets);

src/utils.ts

@@ -1,4 +1,4 @@
-import { Bytes, ethereum, log } from "@graphprotocol/graph-ts";
+import { Bytes, ethereum, log, BigInt } from "@graphprotocol/graph-ts";
 
 export namespace EventType {
   export const SUPPLY = "SUPPLY";
@@ -22,3 +22,8 @@ export function generateLogId(event: ethereum.Event): Bytes {
 
   return event.transaction.hash.concat(logIndex);
 }
+
+export function zeroFloorPlus(a: BigInt, b: BigInt): BigInt {
+  const result = a.plus(b);
+  return result.gt(BigInt.zero()) ? result : BigInt.zero();
+}