React hook for using a Sanity dataset as a general messaging system between users

useSanityMessaging.ts

import { useCallback, useEffect } from "react";
import type { SanityClient, SanityDocument } from "@sanity/client";
import {nanoid} from "nanoid"

type Params<T> = {
  id: string;
  client: SanityClient;
  handler: (from: string, payload: T) => Promise<void>;
};

export function useSanityMessaging<T>({ id, handler, client }: Params<T>) {
  type Message = SanityDocument<{
    payload: T,
    from: string
  }>

  // Sending a message to another party is done by creating a document with a
  // known _type
  const write = useCallback(
    (to: string, payload: T) => {
      client.create({
        ...{ payload },
        from: id,
        _id: `private.${nanoid()}`,
        _type: `messages.${to}`,
      });
    },
    [client, id]
  );

  // Receiving a message from another party is done by subscribing to created
  // documents of a known _type
  useEffect(() => {
    const subscription = client
      .listen<Message>("* [_type == $type]", { type: `messages.${id}` })
      .subscribe((update) => {
        if (update.transition === "appear") {
          // A document of the _type we're interested in was created
          const document = update.result;
          const { from, payload, _id } = document;
          // Tell our handler, then delete the document
          handler(from, payload).then(() => client.delete(_id));
        }
      });
    return () => subscription.unsubscribe();
  }, [id, client]);

  return write;
}