From ae7981c68b36193191f4e6e3f0511577cb093733 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Andr=C3=A9s=20Elizondo?= <andres@0xproject.com>
Date: Wed, 29 May 2024 14:40:07 -0500
Subject: [PATCH] Adds support for multiple ABIs for ERC20 Transfer events.

---
 src/abis.ts                                 |  2 +-
 src/parsers/events/erc20_transfer_events.ts | 26 +++++++++++++--------
 2 files changed, 17 insertions(+), 11 deletions(-)

diff --git a/src/abis.ts b/src/abis.ts
index 2d40966d..9e6a2321 100644
--- a/src/abis.ts
+++ b/src/abis.ts
@@ -1427,7 +1427,7 @@ export const STAKING_REWARDS_PAID_ABI = {
     type: 'event',
 };
 
-export const ERC20_TRANSFER_ABI = {
+export const STANDARD_ERC20_TRANSFER_ABI = {
     anonymous: false,
     inputs: [
         {
diff --git a/src/parsers/events/erc20_transfer_events.ts b/src/parsers/events/erc20_transfer_events.ts
index b5f69626..e79bfecc 100644
--- a/src/parsers/events/erc20_transfer_events.ts
+++ b/src/parsers/events/erc20_transfer_events.ts
@@ -1,4 +1,4 @@
-import { ERC20_TRANSFER_ABI } from '../../constants';
+import { STANDARD_ERC20_TRANSFER_ABI } from '../../constants';
 import { ERC20TransferEvent } from '../../entities';
 import { parseEvent } from './parse_event';
 import { BigNumber } from '@0x/utils';
@@ -13,17 +13,23 @@ export function parseERC20TransferEvent(eventLog: LogEntry): ERC20TransferEvent
 
     parseEvent(eventLog, eRC20TransferEvent);
 
-    // ERC20 Transfers have 3 topics and 32 bytes of data
-    // ERC721 Transfers have 4 topics and no data
-    if (eventLog.topics.length !== 3) {
+    if (eventLog.topics.length === 4 && eventLog.data === '0x') {
+        // ERC721 Transfer - 4 topics, no data
+        return null;
+    } else if (eventLog.topics.length === 3 && eventLog.data !== '0x') {
+        // Standard ERC20 Transfer - 3 topics, 32 bytes of data
+        const decodedLog = abiCoder.decodeLog(
+            STANDARD_ERC20_TRANSFER_ABI.inputs,
+            eventLog.data,
+            eventLog.topics.slice(1),
+        );
+
+        eRC20TransferEvent.from = decodedLog.from.toLowerCase();
+        eRC20TransferEvent.to = decodedLog.to.toLowerCase();
+        eRC20TransferEvent.value = new BigNumber(decodedLog.value);
+    } else {
         return null;
     }
 
-    const decodedLog = abiCoder.decodeLog(ERC20_TRANSFER_ABI.inputs, eventLog.data, eventLog.topics.slice(1));
-
-    eRC20TransferEvent.from = decodedLog.from.toLowerCase();
-    eRC20TransferEvent.to = decodedLog.to.toLowerCase();
-    eRC20TransferEvent.value = new BigNumber(decodedLog.value);
-
     return eRC20TransferEvent;
 }