fix: sum total amount leaving the taker's account

Some trades involve a sell tax, which needs to be accounted for. By including
both the output amount and the sell tax, we can calculate the total amount
leaving the user's wallet. Otherwise, only the tax is shown as the amount
leaving the wallet.

resolves #72

src/index.ts

@@ -86,7 +86,13 @@ export async function parseSwap({
     (log) => log.from.toLowerCase() === taker.toLowerCase()
   );
 
-  let input = fromTaker.length ? fromTaker[0] : logs[0];
+  let input = fromTaker.length
+    ? fromTaker.reduce((acc, curr) => ({
+        ...acc,
+        amount: formatUnits(acc.amountRaw + curr.amountRaw, curr.decimals),
+        amountRaw: acc.amountRaw + curr.amountRaw,
+      }))
+    : logs[0];
 
   let output =
     nativeAmountToTaker === "0"

src/tests/index.test.ts

@@ -550,6 +550,37 @@ test("parse a gasless swap on Base (DEGEN for USDC) for SettlerMetaTxn", async (
   });
 });
 
+// https://basescan.org/tx/0x3d032fdd216315c3dce7bcafeac0805ec18d27c7c9fdf43836cab7fb61332a6d
+test("parse a swap on Base (KEIRA for ETH) for Settler", 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 =
+    "0x3d032fdd216315c3dce7bcafeac0805ec18d27c7c9fdf43836cab7fb61332a6d";
+
+  const result = await parseSwap({
+    publicClient,
+    transactionHash,
+  });
+
+  expect(result).toEqual({
+    tokenIn: {
+      symbol: "KEIRA",
+      amount: "27538.512122127777968652",
+      address: "0x710eEc215b3bB653d42fC6e70E0531eA13F51A7A",
+    },
+    tokenOut: {
+      symbol: "ETH",
+      amount: "0.035509880980229712",
+      address: "0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE",
+    },
+  });
+});
+
 // https://arbiscan.io/tx/0xb2c05194e4ec9ae0f82098ec82a606df544e87c8d6b7726bbb4b1dcc023cb9d7
 test("parse a gasless swap on on Arbitrum (ARB for ETH)", async () => {
   const publicClient = createPublicClient({

src/types.ts

@@ -50,6 +50,7 @@ export interface EnrichedLog {
   amount: string;
   address: Address;
   decimals: number;
+  amountRaw: bigint;
 }
 
 export interface Trace {

src/utils/index.ts

@@ -107,12 +107,13 @@ export async function transferLogs({
       const decimals = results[midpoint + index].result as number;
       const amount =
         log.data === "0x" ? "0" : formatUnits(BigInt(log.data), decimals);
+      const amountRaw = log.data === "0x" ? 0n : BigInt(log.data);
       const { address, topics } = log;
       const { 1: fromHex, 2: toHex } = topics;
       const from = getAddress(convertHexToAddress(fromHex));
       const to = getAddress(convertHexToAddress(toHex));
 
-      return { to, from, symbol, amount, address, decimals };
+      return { to, from, symbol, amount, amountRaw, address, decimals };
     })
     .filter((log) => log.amount !== "0");