import cluster from "node:cluster";
import { rpcFromIpc } from "rpc-async";

/* optional interface */
interface Server {
  add: (a: number, b: number) => number;
  disconnect: () => void;
}

if (cluster.isPrimary) {
  /* --- MAIN PROCESS ---- */
  const worker = cluster.fork();
  const rpc = rpcFromIpc(worker);
  /* Implement and expose local methods.  
  ✅ Use generics for type safety */
  rpc.expose<Server>({
    add: (a: number, b: number) => a + b,
    disconnect: () => cluster.disconnect(),
  });
} else {
  /* --- CHILD PROCESS ---- */
  /* ✅ Use generics for code completion */
  const rpc = rpcFromIpc<Server>(process);
  /* rpc.request[method]() invokes promisified non void remote methods */
  const sum = await rpc.request.add(3, 4);
  console.log("sum =", sum); // => 7
  /* rpc.notify[method]() invokes void remote methods */
  rpc.notify.disconnect();
}

/* -- pseudocode for an imaginary "com"unication channel -- */
import { createRpc, type Handler } from 'rpc-async'

export function myCustomRpc<T extends Handler>(com: any) {
  return createRpc<T>({
    /* required: send messages */
    send: (msg) => com.send(msg),
    /* required: listen to and route incoming messages. Should return a detach function */
    attach: (route) => {
      com.on("message", route)
      return () => com.removeListener("message", route)
    },
    /* optional message codec, depending on the needs of your communication channel */
    encode: (obj: any) => JSON.stringify(obj),
    decode: (text: string) => JSON.parse(text)
  });
}