pages_api_[b64].ts

/* How to use

    import { getTypes } from "../api/types"
    const result = await getTypes("https://esm.sh/react");
    if (result.hasTypes) {
      console.log(result.typesCode);
    }
*/
import { NextApiHandler } from "next";
import fetch from "isomorphic-unfetch";

type GetTypesResponse =
  | {
      hasTypes: true;
      typesUrl: string;
      typesCode: string;
    }
  | {
      hasTypes: false;
    };

const handler: NextApiHandler<GetTypesResponse> = async (req, res) => {
  const b64 = req.query["b64"] as string;
  const codeUrl = Buffer.from(b64, "base64").toString("utf-8");
  try {
    const response = await fetch(codeUrl);
    const typesUrl = response.headers.get("x-typescript-types") as string;
    if (typesUrl == null) {
      return res.json({ hasTypes: false });
    }
    const typesCode = await fetch(typesUrl).then((res) => {
      return res.text();
    });
    res.json({ typesUrl, typesCode, hasTypes: true });
  } catch (err) {
    res.status(400).end();
  }
};

export default handler;

export async function getTypes(url: string): Promise<GetTypesResponse> {
  const encoded = btoa(url);
  return fetch(`/api/types/${encoded}`).then((res) => res.json());
}