#!/usr/bin/env node
/**
 * @file Detached helper spawned by `server/lib/self-restart.js`. Polls the
 * old dashboard PID until it exits (server/index.js's own SIGTERM handler
 * has a 5s force-exit backstop, so this never waits forever), then starts a
 * fresh server from the same entry point and exits itself. The new server's
 * stdout/stderr are appended to the log file it is given (the checkout's
 * `data/agenthub-server.log`, the one `agenthub start` writes), so a crash
 * after an update still leaves Node's stack trace behind.
 * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
 */

require("../server/lib/windows-hide").install(); // before child_process is read
const fs = require("fs");
const path = require("path");
const { spawn } = require("child_process");
const { rotateIfLarge } = require("./log-rotate");

const [, , pidArg, entry, logArg] = process.argv;
const pid = parseInt(pidArg, 10);

// ponytail: fixed poll cadence/cap, not configurable — this script has one caller.
const POLL_MS = 200;
const MAX_WAIT_MS = 20_000;

function isAlive(p) {
  try {
    process.kill(p, 0);
    return true;
  } catch {
    return false;
  }
}

/** Append fd for the new server's output, or "ignore" when there is none. */
function openLog(file) {
  if (!file) return "ignore";
  try {
    fs.mkdirSync(path.dirname(file), { recursive: true });
    rotateIfLarge(file);
    const fd = fs.openSync(file, "a");
    fs.writeSync(fd, `[${new Date().toISOString()}] restart-helper: old server ${pid} gone, starting ${entry}\n`);
    return fd;
  } catch {
    return "ignore"; // a log must never stop the restart
  }
}

function restart() {
  const out = openLog(logArg);
  const child = spawn(process.execPath, [entry], {
    detached: true,
    stdio: ["ignore", out, out],
    env: process.env,
  });
  child.unref();
  process.exit(0);
}

function waitAndRestart(waited = 0) {
  if (isAlive(pid) && waited < MAX_WAIT_MS) {
    setTimeout(() => waitAndRestart(waited + POLL_MS), POLL_MS);
    return;
  }
  restart();
}

waitAndRestart();