From 9683edf050feb44803e319ef6e0ae09ced8b3c10 Mon Sep 17 00:00:00 2001
From: Willian Mitsuda <wmitsuda@gmail.com>
Date: Tue, 23 Aug 2022 17:29:54 -0300
Subject: [PATCH] Convert token metadata logic into SWR fetcher

---
 src/TokenTransferItem.tsx   | 11 ++---
 src/transaction/Details.tsx |  6 +--
 src/types.ts                |  1 -
 src/useErigonHooks.ts       | 82 ++++++++++++++++++++++++-------------
 4 files changed, 58 insertions(+), 42 deletions(-)

diff --git a/src/TokenTransferItem.tsx b/src/TokenTransferItem.tsx
index 0284a58..5fba3ca 100644
--- a/src/TokenTransferItem.tsx
+++ b/src/TokenTransferItem.tsx
@@ -6,24 +6,21 @@ import TransactionAddress from "./components/TransactionAddress";
 import ValueHighlighter from "./components/ValueHighlighter";
 import FormattedBalance from "./components/FormattedBalance";
 import USDAmount from "./components/USDAmount";
-import { AddressContext, TokenMeta, TokenTransfer } from "./types";
 import { RuntimeContext } from "./useRuntime";
 import { useBlockNumberContext } from "./useBlockTagContext";
+import { useTokenMetadata } from "./useErigonHooks";
 import { useTokenUSDOracle } from "./usePriceOracle";
+import { AddressContext, TokenTransfer } from "./types";
 
 type TokenTransferItemProps = {
   t: TokenTransfer;
-  tokenMeta?: TokenMeta | null | undefined;
 };
 
-// TODO: handle partial
-const TokenTransferItem: React.FC<TokenTransferItemProps> = ({
-  t,
-  tokenMeta,
-}) => {
+const TokenTransferItem: React.FC<TokenTransferItemProps> = ({ t }) => {
   const { provider } = useContext(RuntimeContext);
   const blockNumber = useBlockNumberContext();
   const [quote, decimals] = useTokenUSDOracle(provider, blockNumber, t.token);
+  const tokenMeta = useTokenMetadata(provider, t.token);
 
   return (
     <div className="flex items-baseline space-x-2 px-2 py-1 truncate hover:bg-gray-100">
diff --git a/src/transaction/Details.tsx b/src/transaction/Details.tsx
index 6932f5c..bb41b04 100644
--- a/src/transaction/Details.tsx
+++ b/src/transaction/Details.tsx
@@ -285,11 +285,7 @@ const Details: React.FC<DetailsProps> = ({ txData }) => {
       {txData.tokenTransfers.length > 0 && (
         <InfoRow title={`Tokens Transferred (${txData.tokenTransfers.length})`}>
           {txData.tokenTransfers.map((t, i) => (
-            <TokenTransferItem
-              key={i}
-              t={t}
-              tokenMeta={txData.tokenMetas[t.token]}
-            />
+            <TokenTransferItem key={i} t={t} />
           ))}
         </InfoRow>
       )}
diff --git a/src/types.ts b/src/types.ts
index 44a134b..06d7c69 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -37,7 +37,6 @@ export type TransactionData = {
   to?: string;
   value: BigNumber;
   tokenTransfers: TokenTransfer[];
-  tokenMetas: TokenMetas;
   type: number;
   maxFeePerGas?: BigNumber | undefined;
   maxPriorityFeePerGas?: BigNumber | undefined;
diff --git a/src/useErigonHooks.ts b/src/useErigonHooks.ts
index a3620b7..61037fe 100644
--- a/src/useErigonHooks.ts
+++ b/src/useErigonHooks.ts
@@ -13,13 +13,13 @@ import { arrayify, hexDataSlice, isHexString } from "@ethersproject/bytes";
 import useSWR from "swr";
 import useSWRImmutable from "swr/immutable";
 import {
-  TokenMetas,
   TokenTransfer,
   TransactionData,
   InternalOperation,
   ProcessedTransaction,
   OperationType,
   ChecksummedAddress,
+  TokenMeta,
 } from "./types";
 import erc20 from "./erc20.json";
 
@@ -216,40 +216,12 @@ export const useTxData = (
           }
         }
 
-        // Extract token meta
-        const tokenMetas: TokenMetas = {};
-        for (const t of tokenTransfers) {
-          if (tokenMetas[t.token] !== undefined) {
-            continue;
-          }
-          const erc20Contract = new Contract(t.token, erc20, provider);
-          try {
-            const [name, symbol, decimals] = await Promise.all([
-              erc20Contract.name(),
-              erc20Contract.symbol(),
-              erc20Contract.decimals(),
-            ]);
-            tokenMetas[t.token] = {
-              name,
-              symbol,
-              decimals,
-            };
-          } catch (err) {
-            tokenMetas[t.token] = null;
-            console.warn(
-              `Couldn't get token ${t.token} metadata; ignoring`,
-              err
-            );
-          }
-        }
-
         setTxData({
           transactionHash: _response.hash,
           from: _response.from,
           to: _response.to,
           value: _response.value,
           tokenTransfers,
-          tokenMetas,
           type: _response.type ?? 0,
           maxFeePerGas: _response.maxFeePerGas,
           maxPriorityFeePerGas: _response.maxPriorityFeePerGas,
@@ -665,3 +637,55 @@ export const useHasCode = (
   }
   return data as boolean | undefined;
 };
+
+const tokenMetadataFetcher =
+  (provider: JsonRpcProvider | undefined) =>
+  async (
+    _: "tokenmeta",
+    address: ChecksummedAddress
+  ): Promise<TokenMeta | null> => {
+    const erc20Contract = new Contract(address, erc20, provider);
+    try {
+      const name = (await erc20Contract.name()) as string;
+      if (!name.trim()) {
+        return null;
+      }
+
+      const [symbol, decimals] = (await Promise.all([
+        erc20Contract.symbol(),
+        erc20Contract.decimals(),
+      ])) as [string, number];
+
+      // Prevent faulty tokens with empty name/symbol
+      if (!symbol.trim()) {
+        return null;
+      }
+
+      return {
+        name,
+        symbol,
+        decimals,
+      };
+    } catch (err) {
+      // Ignore on purpose; this indicates the probe failed and the address
+      // is not a token
+      return null;
+    }
+  };
+
+export const useTokenMetadata = (
+  provider: JsonRpcProvider | undefined,
+  address: ChecksummedAddress | undefined
+): TokenMeta | null | undefined => {
+  const fetcher = tokenMetadataFetcher(provider);
+  const { data, error } = useSWRImmutable(
+    provider !== undefined && address !== undefined
+      ? ["tokenmeta", address]
+      : null,
+    fetcher
+  );
+  if (error) {
+    return undefined;
+  }
+  return data;
+};