import { Rcon } from "rcon-client";
import { MC_SERVER_IP, RCON_PORT, RCON_PASSWORD } from "./constants";

let pooled: Rcon | null = null;
let connecting: Promise<Rcon> | null = null;
let idleTimer: NodeJS.Timeout | null = null;
const IDLE_MS = 30_000;

async function open(): Promise<Rcon> {
  const rcon = await Rcon.connect({
    host: MC_SERVER_IP,
    port: RCON_PORT,
    password: RCON_PASSWORD,
    timeout: 5000,
  });
  rcon.on("end", () => {
    if (pooled === rcon) pooled = null;
  });
  rcon.on("error", () => {
    if (pooled === rcon) pooled = null;
  });
  return rcon;
}

function scheduleIdleClose() {
  if (idleTimer) clearTimeout(idleTimer);
  idleTimer = setTimeout(() => {
    const r = pooled;
    pooled = null;
    idleTimer = null;
    r?.end().catch(() => {});
  }, IDLE_MS);
}

async function getConnection(): Promise<Rcon> {
  if (pooled) return pooled;
  if (connecting) return connecting;
  connecting = open()
    .then((r) => {
      pooled = r;
      return r;
    })
    .finally(() => {
      connecting = null;
    });
  return connecting;
}

export async function sendCommand(command: string): Promise<string> {
  try {
    const rcon = await getConnection();
    const response = await rcon.send(command);
    scheduleIdleClose();
    return response;
  } catch (e) {
    // Drop the pooled connection on any error, retry once with fresh
    const bad = pooled;
    pooled = null;
    bad?.end().catch(() => {});
    const rcon = await getConnection();
    const response = await rcon.send(command);
    scheduleIdleClose();
    return response;
  }
}