/** 管理员网页更新入口。安装由独立 systemd 单元执行，重启 ERP 不会杀掉更新任务。 */
const fs = require('fs');
const path = require('path');
const crypto = require('crypto');
const { execFile } = require('child_process');
const { promisify } = require('util');
const exec = promisify(execFile);
const updater = require('./updater');
const ROOT = path.resolve(__dirname, '../..');
const DATA = path.resolve(process.env.DATA_DIR || path.join(ROOT, 'backend/data'));
const DIR = path.join(DATA, 'system-update');
const STATUS = path.join(DIR, 'status.json');
const LOCK = path.join(DIR, 'lock');
const SERVICE = process.env.HAPPY_UPDATE_SERVICE || 'erp';

let lastInspection = 0;
async function readStatus() {
  let status;
  try { status = JSON.parse(fs.readFileSync(STATUS, 'utf8')); }
  catch { return { state: 'idle', message: '尚未执行更新' }; }
  if (process.platform === 'linux' && /^[a-f0-9]{16}$/.test(status.id || '')
      && !['idle', 'completed', 'failed'].includes(status.state)
      && Date.now() - Date.parse(status.startedAt) > 60000 && Date.now() - lastInspection > 30000) {
    lastInspection = Date.now();
    try {
      const { stdout } = await exec('systemctl', ['show', `happy-update-${status.id}.service`, '--property=ActiveState', '--value'], { timeout: 5000 });
      if (['inactive', 'failed'].includes(stdout.trim())) {
        // 再读一次，避免 worker 刚完成时被旧状态覆盖。
        const latest = JSON.parse(fs.readFileSync(STATUS, 'utf8'));
        if (latest.id === status.id && !['completed', 'failed'].includes(latest.state)) {
          status = { ...latest, state: 'failed', message: '更新任务意外中断，请查看日志；数据库备份与恢复目录已保留', finishedAt: new Date().toISOString() };
          fs.writeFileSync(STATUS, JSON.stringify(status), { mode: 0o600 });
          fs.rmSync(LOCK, { force: true });
        } else status = latest;
      }
    } catch { /* systemd 暂不可达时保留状态，不能认定任务已终止 */ }
  }
  return status;
}
function capability() {
  return { supported: process.platform === 'linux', service: SERVICE,
    reason: process.platform === 'linux' ? '' : '网页安装支持 Linux systemd 部署；当前环境可检查版本。' };
}
async function start(req) {
  if (!capability().supported) throw Object.assign(new Error(capability().reason), { statusCode: 400 });
  if (!/^[a-zA-Z0-9_.@-]+$/.test(SERVICE)) throw new Error('更新服务名配置无效');
  await exec('systemctl', ['is-active', `${SERVICE}.service`], { timeout: 10000 });
  const dirty = await exec('git', ['status', '--porcelain', '--untracked-files=normal'], { cwd: ROOT, timeout: 10000 });
  if (dirty.stdout.trim()) throw Object.assign(new Error('部署目录有未提交或未跟踪的文件，请先处理后再更新'), { statusCode: 409 });
  const repo = updater.normalizeRepo(process.env.HAPPY_UPDATE_REPO || updater.DEFAULT_REPO);
  if (!repo || !/^[a-zA-Z0-9_.-]+\/[a-zA-Z0-9_.-]+$/.test(repo)) throw new Error('服务器更新源配置无效');
  fs.mkdirSync(DIR, { recursive: true, mode: 0o700 });
  try { fs.writeFileSync(LOCK, String(Date.now()), { flag: 'wx', mode: 0o600 }); }
  catch (error) {
    if (error.code === 'EEXIST') throw Object.assign(new Error('已有更新任务正在执行'), { statusCode: 409 });
    throw error;
  }
  try {
    const result = await updater.checkUpdate(repo);
    if (!result.ok) throw new Error(result.error);
    if (!result.hasUpdate) throw Object.assign(new Error('当前已是最新版本'), { statusCode: 409 });
    if (!/^v?\d+\.\d+\.\d+(?:-[a-zA-Z0-9.-]+)?$/.test(result.tag)) throw new Error('版本标签无效');
    const id = crypto.randomBytes(8).toString('hex');
    const jobDir = path.join(DIR, id);
    fs.mkdirSync(jobDir, { mode: 0o700 });
    const worker = path.join(jobDir, 'worker.js');
    fs.copyFileSync(path.join(__dirname, 'updateWorker.js'), worker);
    const config = path.join(jobDir, 'config.json');
    fs.writeFileSync(config, JSON.stringify({ root: ROOT, data: DATA, dir: DIR, jobDir, service: SERVICE,
      repo, tag: result.tag, version: result.latest, node: process.execPath, port: process.env.PORT || '4300' }), { mode: 0o600 });
    const status = { id, state: 'queued', message: '更新任务已创建', version: result.latest,
      startedAt: new Date().toISOString(), username: req.user.username };
    fs.writeFileSync(STATUS, JSON.stringify(status), { mode: 0o600 });
    await exec('systemd-run', ['--unit', `happy-update-${id}`, '--collect', '--property=Type=exec',
      process.execPath, worker, config], { timeout: 15000 });
    return status;
  } catch (error) {
    fs.rmSync(LOCK, { force: true });
    fs.writeFileSync(STATUS, JSON.stringify({ state: 'failed', message: error.message, finishedAt: new Date().toISOString() }), { mode: 0o600 });
    throw error;
  }
}
module.exports = { start, readStatus, capability };