/// <reference no-default-lib="true" />
/// <reference lib="esnext" />
/// <reference lib="dom" />
import type {
  Socket, Manager, ManagerOptions, SocketOptions,
} from "https://cdn.esm.sh/v54/socket.io-client@4.2.0/build/index.d.ts";
export type { Socket, Manager, ManagerOptions, SocketOptions };

declare function io(uri: string, opts?: Partial<ManagerOptions & SocketOptions>): Socket;
const version = "4.2.0";

export async function socketIO(): Promise<Socket> {
  const io = await importSocketIO();
  return io("https://scrapbox.io", {reconnectionDelay: 5000, transports: ["websocket"]});
}

function importSocketIO(): Promise<typeof io> {
  const url = `https://cdnjs.cloudflare.com/ajax/libs/socket.io/${version}/socket.io.min.js`;
  if (document.querySelector(`script[src="${url}"]`)) {
    return Promise.resolve(io);
  }
  
  const script = document.createElement("script");
  script.src = url;
  return new Promise((resolve, reject) => {
    script.onload = () => resolve(io);
    script.onerror = (e) => reject(e);
    document.head.append(script);
  });
}