From b9f166e864eaf14633b1373725dbf26f1966cc4a Mon Sep 17 00:00:00 2001
From: ponyjackal <pony1125@outlook.com>
Date: Thu, 30 Nov 2023 04:04:47 -0800
Subject: [PATCH 1/2] feat: update erc20Swap

---
 src/heuristics/erc20Swap.ts | 39 ++++++++++++++++++++++++++-----------
 1 file changed, 28 insertions(+), 11 deletions(-)

diff --git a/src/heuristics/erc20Swap.ts b/src/heuristics/erc20Swap.ts
index 65f711fd..34d63c7d 100644
--- a/src/heuristics/erc20Swap.ts
+++ b/src/heuristics/erc20Swap.ts
@@ -7,6 +7,18 @@ export function erc20SwapContextualizer(transaction: Transaction): Transaction {
   return generateERC20SwapContext(transaction);
 }
 
+/**
+ * Detection criteria
+ *
+ * We should detect an ERC20 swap if:
+ * The from account sent and received 1 asset. The sent and received must be either ETH OR an ERC20.
+ * Only 1 other account sends and receives assets (the liquidity pool).
+ * This is a simple check against the other addresses in netAssetTransfers (sent.length === 1 && received.length===1)
+ * Only 4 addresses max in netAssetTransfers.
+ *
+ * This is because when using a router there are likely other parties receiving fees. Some erc20s take a fee for any transfers as well. 4 addresses should be safe.
+ * To generate the erc20 swap, only look at the tx.from address in netAssetTransfers to pull out the sent/received (i.e., swapped from token X <> to token Y)
+ */
 export function detectERC20Swap(transaction: Transaction): boolean {
   /**
    * There is a degree of overlap between the 'detect' and 'generateContext' functions,
@@ -23,17 +35,22 @@ export function detectERC20Swap(transaction: Transaction): boolean {
   if (!addresses.includes(transaction.from.toLowerCase())) {
     return false;
   }
-
-  for (const address of addresses) {
-    const sent = transaction.netAssetTransfers[address].sent;
-    const received = transaction.netAssetTransfers[address].received;
-
-    const sentCount = sent?.length || 0;
-    const receivedCount = received?.length || 0;
-
-    if (sentCount === 1 && receivedCount === 1 && sent[0].type === 'erc20') {
-      return true;
-    }
+  // check netAssetTransfer addresses
+  if (addresses.length > 4) {
+    return false;
+  }
+  // check if transfer.from sent and receive one asset
+  const sent = transaction.netAssetTransfers[transaction.from].sent;
+  const received = transaction.netAssetTransfers[transaction.from].received;
+  const sentCount = sent?.length || 0;
+  const receivedCount = received?.length || 0;
+  // check if only one asset was transferred
+  if (sentCount !== 1 || receivedCount !== 1) {
+    return false;
+  }
+  // check if asset transferred is erc20 or eth
+  if (sent[0].type === 'erc20' || sent[0].type === 'eth') {
+    return true;
   }
 
   return false;

From 4541517a4aa12d114d92274f6eb62799a5c23f9a Mon Sep 17 00:00:00 2001
From: Paul Cowgill <pauldavidcowgill@gmail.com>
Date: Thu, 30 Nov 2023 10:09:13 -0600
Subject: [PATCH 2/2] Grammar fix

---
 src/heuristics/erc20Swap.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/heuristics/erc20Swap.ts b/src/heuristics/erc20Swap.ts
index 34d63c7d..2a66091c 100644
--- a/src/heuristics/erc20Swap.ts
+++ b/src/heuristics/erc20Swap.ts
@@ -39,7 +39,7 @@ export function detectERC20Swap(transaction: Transaction): boolean {
   if (addresses.length > 4) {
     return false;
   }
-  // check if transfer.from sent and receive one asset
+  // check if transfer.from sent and received one asset
   const sent = transaction.netAssetTransfers[transaction.from].sent;
   const received = transaction.netAssetTransfers[transaction.from].received;
   const sentCount = sent?.length || 0;