From 1d659a6f01db14f409f6f8f117189d06809e1b4f Mon Sep 17 00:00:00 2001
From: hzhu <hz@henryzhu.me>
Date: Wed, 10 Jul 2024 00:59:01 -0700
Subject: [PATCH] fix: native transfers with SettlerMetaTxn

---
 src/parseSwapV2.ts            | 33 +++++++++++++++++++++++++++++++++
 src/tests/parseSwapV2.test.ts | 31 +++++++++++++++++++++++++++++++
 2 files changed, 64 insertions(+)

diff --git a/src/parseSwapV2.ts b/src/parseSwapV2.ts
index 1bde04f..84180d6 100644
--- a/src/parseSwapV2.ts
+++ b/src/parseSwapV2.ts
@@ -63,6 +63,16 @@ export const NATIVE_SYMBOL_BY_CHAIN_ID: { [key in SupportedChainId]: string } =
     43114: "AVAX", // Avalanche
   };
 
+const SETTLER_META_TXN_BY_CHAIN_ID: { [key in SupportedChainId]: string } = {
+  1: "0x7C39a136EA20B3483e402EA031c1f3C019bAb24b",
+  10: "0x4069560a180EbD76bB1aF947f5119Fe555BB4eA0",
+  56: "0x73C25Ef091Ce3F2451946Be3f982549776bFED31",
+  137: "0xF9332450385291b6dcE301917aF6905e28E8f35f",
+  8453: "0x5CE929DDB01804bfF35B2F5c77b735bdB094AAc8",
+  42161: "0x1aa84EB5cb62f686FC0D908AFd85864f4A05d5Ee",
+  43114: "0x2adb2cE26848B94E13d2f7fE0fF7E945050D741c",
+};
+
 const MULTICALL3_ADDRESS = "0xcA11bde05977b3631167028862bE2a173976CA11";
 
 export function isChainIdSupported(
@@ -280,6 +290,26 @@ export async function parseSwapV2({
     }
   }
 
+  const isSettlerMetaTxn =
+    to?.toLowerCase() === SETTLER_META_TXN_BY_CHAIN_ID[chainId].toLowerCase();
+
+  if (isSettlerMetaTxn) {
+    const { args } = decodeFunctionData<any[]>({
+      abi: settlerAbi,
+      data: transaction.input,
+    });
+
+    const taker = args[0].recipient.toLowerCase() as Address;
+
+    const nativeTransferAmount = extractNativeTransfer(trace, taker);
+
+    output = {
+      symbol: NATIVE_SYMBOL_BY_CHAIN_ID[chainId],
+      amount: nativeTransferAmount,
+      address: NATIVE_TOKEN_ADDRESS,
+    };
+  }
+
   if (isNativeSell) {
     const nativeSellAmount = formatEther(value);
     const tokenOut = logs
@@ -307,6 +337,9 @@ export async function parseSwapV2({
   }
 
   if (!output) {
+    console.error(
+      "An error has occurred. File a bug report here: https://github.com/0xProject/0x-parser/issues/new/choose"
+    );
     return null;
   }
 
diff --git a/src/tests/parseSwapV2.test.ts b/src/tests/parseSwapV2.test.ts
index 76868a4..9736d9d 100644
--- a/src/tests/parseSwapV2.test.ts
+++ b/src/tests/parseSwapV2.test.ts
@@ -414,6 +414,37 @@ test("parse a gasless swap on Base (USDC for DEGEN)", async () => {
   });
 });
 
+// https://basescan.org/tx/0x14416958953850c5c5a572d6e8cb832c032d0678b3ce9da6cdce891a20864b99
+test("parse a gasless swap on Base (USDC for ETH) for SettlerMetaTxn", async () => {
+  const publicClient = createPublicClient({
+    chain: base,
+    transport: http(
+      `https://base-mainnet.g.alchemy.com/v2/${process.env.ALCHEMY_API_KEY}`
+    ),
+  }) as PublicClient<Transport, Chain>;
+
+  const transactionHash =
+    "0x14416958953850c5c5a572d6e8cb832c032d0678b3ce9da6cdce891a20864b99";
+
+  const result = await parseSwapV2({
+    publicClient,
+    transactionHash,
+  });
+
+  expect(result).toEqual({
+    tokenIn: {
+      symbol: "USDC",
+      amount: "21.27865",
+      address: "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
+    },
+    tokenOut: {
+      symbol: "ETH",
+      amount: "0.006847116541535933",
+      address: NATIVE_ASSET.address,
+    },
+  });
+});
+
 // https://arbiscan.io/tx/0xb2c05194e4ec9ae0f82098ec82a606df544e87c8d6b7726bbb4b1dcc023cb9d7
 test("parse a gasless swap on on Arbitrum (ARB for ETH)", async () => {
   const publicClient = createPublicClient({