/**
 * @file autostart.js
 * @description Settings → System's "Start automatically" switch: whether the
 * dashboard starts at boot/login through the per-user service
 * (`scripts/service-manager.js` — a systemd `--user` unit, or a LaunchAgent on
 * macOS). The switch IS the unit's enabled state, nothing stored beside it.
 * Turning it on writes a unit for THIS server when none exists, and enables
 * it; turning it off disables it. Neither ever starts or stops anything — the
 * server answering the click is the one that would die. Off by default: the
 * plugin bootstrap installs no unit until the user opts in.
 * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
 */

const fs = require("fs");
const path = require("path");
const svc = require("../../scripts/service-manager");

const NAME = "agenthub";
const ROOT = path.resolve(__dirname, "..", "..");

/** A unit by our name that AgentHub did not write — never ours to touch. */
function isForeign() {
  return fs.existsSync(svc.unitPath(NAME)) && !svc.unitIsOurs(NAME);
}

function status() {
  const available = svc.systemctlAvailable();
  return {
    available,
    kind: svc.kind,
    enabled: available && svc.unitIsEnabled(NAME),
    foreign: isForeign(),
  };
}

/** The unit for the running server — same shape the bootstrap writes. */
function unitForThisServer() {
  const entry = path.join(ROOT, "server", "index.js");
  const env = { NODE_ENV: "production", PATH: process.env.PATH || "" };
  for (const key of ["NODE_PATH", "DASHBOARD_CLIENT_DIST", "DASHBOARD_PORT"]) {
    if (process.env[key]) env[key] = process.env[key];
  }
  return {
    name: NAME,
    description: "AgentHub dashboard server",
    workingDir: ROOT,
    execStart: `${process.execPath} ${entry}`,
    argv: [process.execPath, entry],
    env,
  };
}

function fail(code, message) {
  return Object.assign(new Error(message), { code });
}

function setEnabled(on) {
  if (!svc.systemctlAvailable()) {
    throw fail("EUNAVAILABLE", `no ${svc.label} manager is available on this machine`);
  }
  let result;
  if (svc.unitIsOurs(NAME)) result = svc.setUnitEnabled(NAME, on);
  else if (isForeign()) result = "foreign";
  else if (!on)
    result = "ok"; // nothing installed: already off
  else {
    result = svc.writeUserService(unitForThisServer()); // writes + enables, starts nothing
    if (result === "written") svc.enableLinger();
  }
  if (result === "foreign") {
    throw fail("EFOREIGN", `${svc.unitPath(NAME)} was not written by AgentHub — not touching it`);
  }
  if (result === "failed" || result === "unavailable") {
    throw fail("ESERVICE", `could not change the ${svc.label}`);
  }
  return status();
}

module.exports = { status, setEnabled };