buf connect with next 13 route handlers

connect-nextjs13-adapter.ts

import {
  ConnectRouter,
  ConnectRouterOptions,
  createConnectRouter,
} from "@bufbuild/connect";
import type { UniversalHandler } from "@bufbuild/connect/protocol";
import { createFetchHandler, FetchHandler } from "./fetch-universal-handler"; // https://gist.github.com/timostamm/5ca423155a0ddf03678ddc61f08cf4bd

interface NextJs13ApiRouterOptions extends ConnectRouterOptions {
  /**
   * Route definitions. We recommend the following pattern:
   *
   * Create a file `connect.ts` with a default export such as this:
   *
   * ```ts
   * import {ConnectRouter} from "@bufbuild/connect";
   *
   * export default (router: ConnectRouter) => {
   *   router.service(ElizaService, {});
   * }
   * ```
   *
   * Then pass this function here.
   */
  routes: (router: ConnectRouter) => void;
  prefix?: string;
}

type NextApiRouteHandler = (req: Request) => Promise<Response>;

interface ApiRoute {
  POST: FetchHandler | NextApiRouteHandler;
}

export function next13JsApiRouter(options: NextJs13ApiRouterOptions): ApiRoute {
  const router = createConnectRouter(options);
  options.routes(router);
  const prefix = options.prefix ?? "/api";
  const paths = new Map<string, UniversalHandler>();
  for (const uHandler of router.handlers) {
    paths.set(prefix + uHandler.requestPath, uHandler);
  }

  async function POST(req: Request) {
    const requestPath = new URL(req.url).pathname;
    const uHandler = paths.get(requestPath);
    if (!uHandler) {
      return new Response(null, { status: 404 });
    }
    const fetchHandler = createFetchHandler(uHandler);

    return await fetchHandler(req);
  }

  return {
    POST,
  };
}

route.ts

// app/api/appservice/[[...connect]]/route.ts

import { next13JsApiRouter } from "@/adapters/connect-nextjs13-adapter";
import routes from "@/connect"; // connect router with a service implementation

const { POST } = next13JsApiRouter({
  routes,
  prefix: "/api/appservice",
});

export { POST };