Add api for getting native mainnet, testnet chain infos

pages/api/native-chains.ts

@@ -0,0 +1,60 @@
+// Next.js API route support: https://nextjs.org/docs/api-routes/introduction
+import type { NextApiRequest, NextApiResponse } from "next";
+
+import path from "path";
+import { promises as fs } from "fs";
+import { ChainInfo } from "@keplr-wallet/types";
+import Cors from "cors";
+import {
+  nativeMainnetChainIdentifiers,
+  nativeTestnetChainIdentifiers,
+} from "../../src/constants";
+import { ChainIdHelper } from "@keplr-wallet/cosmos";
+
+type Data = {
+  mainnetChains: ChainInfo[];
+  testnetChains: ChainInfo[];
+};
+
+const cors = Cors({
+  methods: ["GET"],
+});
+
+export default async function (
+  req: NextApiRequest,
+  res: NextApiResponse<Data>,
+) {
+  await new Promise((resolve, reject) => {
+    cors(req, res, (result: any) => {
+      if (result instanceof Error) {
+        return reject(result);
+      }
+
+      return resolve(result);
+    });
+  });
+
+  const jsonDirectory = path.join(process.cwd(), "cosmos");
+
+  const fetchChains = (await fs.readdir(jsonDirectory)).map((fileName) =>
+    fs.readFile(`${jsonDirectory}/${fileName}`, "utf8"),
+  );
+
+  const chainInfos: ChainInfo[] = (await Promise.all(fetchChains)).map(
+    (chainInfo) => JSON.parse(chainInfo),
+  );
+
+  //Return the content of the data file in json format
+  res.status(200).json({
+    mainnetChains: chainInfos.filter((chainInfo) =>
+      nativeMainnetChainIdentifiers.includes(
+        ChainIdHelper.parse(chainInfo.chainId).identifier,
+      ),
+    ),
+    testnetChains: chainInfos.filter((chainInfo) =>
+      nativeTestnetChainIdentifiers.includes(
+        ChainIdHelper.parse(chainInfo.chainId).identifier,
+      ),
+    ),
+  });
+}