fix: simplify wallet choices and use bnb chain

src/wallet/injected.ts

@@ -1,6 +1,14 @@
 import { requestWalletNonce, verifyWalletSignature } from "./api";
 
+export type WalletKind = "tokenPocket" | "metaMask" | "imToken";
+
+const bnbChainIdHex = "0x38";
+
 export type EthereumProvider = {
+  isMetaMask?: boolean;
+  isTokenPocket?: boolean;
+  isImToken?: boolean;
+  providers?: EthereumProvider[];
   request: <T = unknown>(args: {
     method: string;
     params?: unknown[];
@@ -13,13 +21,54 @@ export function getInjectedEthereum(): EthereumProvider | null {
   return maybeWindow.ethereum ?? null;
 }
 
-export async function signInWithInjectedWallet(): Promise<{
+export function getInjectedWallet(kind?: WalletKind): EthereumProvider | null {
+  const ethereum = getInjectedEthereum();
+  if (!ethereum || !kind) return ethereum;
+  const providers = ethereum.providers?.length
+    ? ethereum.providers
+    : [ethereum];
+  const match = providers.find((provider) => {
+    if (kind === "metaMask") return provider.isMetaMask;
+    if (kind === "tokenPocket") return provider.isTokenPocket;
+    if (kind === "imToken") return provider.isImToken;
+    return false;
+  });
+  return match ?? null;
+}
+
+async function ensureBnbChain(ethereum: EthereumProvider): Promise<void> {
+  try {
+    await ethereum.request({
+      method: "wallet_switchEthereumChain",
+      params: [{ chainId: bnbChainIdHex }],
+    });
+  } catch (error) {
+    const code = (error as { code?: number | string }).code;
+    if (code !== 4902 && code !== "4902") throw error;
+    await ethereum.request({
+      method: "wallet_addEthereumChain",
+      params: [
+        {
+          blockExplorerUrls: ["https://bscscan.com"],
+          chainId: bnbChainIdHex,
+          chainName: "BNB Smart Chain",
+          nativeCurrency: { decimals: 18, name: "BNB", symbol: "BNB" },
+          rpcUrls: ["https://bsc-dataseed.binance.org"],
+        },
+      ],
+    });
+  }
+}
+
+export async function signInWithInjectedWallet(kind?: WalletKind): Promise<{
   token: string;
   wallet: string;
 }> {
-  const ethereum = getInjectedEthereum();
+  const ethereum = getInjectedWallet(kind);
   if (!ethereum) throw new Error("No injected wallet found");
 
+  await ensureBnbChain(ethereum);
+
   const accounts = await ethereum.request<string[]>({
     method: "eth_requestAccounts",
   });