'use strict';

// 智慧运营中台 · 引导入口
// 职责仅剩：装配共享状态（server/context.js）→ 挂载路由（server/routes/）→ 监听端口。
// 端口被旧实例占用时自动回收；业务逻辑全部在 server/ 目录下。

const http = require('http');
const path = require('path');
const { execFile } = require('child_process');

const { createContext } = require('./server/context.js');
const { createRouter } = require('./server/router.js');
const { createCrawlService } = require('./server/services/crawl.js');
const { createGenerationService } = require('./server/services/generation.js');
const { createAutoSyncService } = require('./server/services/auto-sync.js');
const { registerRoutes } = require('./server/routes/index.js');

const HOST = process.env.HOST || '127.0.0.1';

const ctx = createContext();
ctx.crawl = createCrawlService(ctx);
ctx.generation = createGenerationService(ctx);
ctx.autoSync = createAutoSyncService(ctx);

const app = createRouter();
registerRoutes(app, ctx);

const server = http.createServer((req, res) => {
  app.dispatch(req, res);
});

// 恢复上次未完成的生成任务（重启后仍可轮询已提交的任务）
ctx.generation.loadPersistedJobs();

// PORT 环境变量可临时覆盖 config.json 的端口（多实例/调试用，不落盘）
const LISTEN_PORT = Number(process.env.PORT || ctx.config.port) || ctx.config.port;

function runCmd(cmd, args, timeoutMs = 8000) {
  return new Promise((resolve) => {
    execFile(cmd, args, { timeout: timeoutMs }, (err, stdout) => resolve(err ? '' : String(stdout || '')));
  });
}

/** 找出正在监听指定端口的 PID 列表 */
async function pidsListeningOnPort(port) {
  if (process.platform === 'win32') {
    const out = await runCmd('powershell', ['-NoProfile', '-Command',
      `(Get-NetTCPConnection -LocalPort ${port} -State Listen -ErrorAction SilentlyContinue | Select-Object -ExpandProperty OwningProcess -Unique) -join ','`]);
    return out.trim().split(',').map((s) => parseInt(s, 10)).filter((n) => Number.isInteger(n) && n > 0);
  }
  const out = await runCmd('lsof', ['-ti', `tcp:${port}`, '-s', 'TCP:LISTEN']);
  return out.trim().split('\n').map((s) => parseInt(s, 10)).filter((n) => Number.isInteger(n) && n > 0);
}

/** 校验该 PID 是否是「本项目的 server.js」（命令行 + 工作目录双重确认，避免误杀无关进程） */
async function isOurServerProcess(pid) {
  try {
    if (process.platform === 'win32') {
      const out = await runCmd('powershell', ['-NoProfile', '-Command',
        `(Get-CimInstance Win32_Process -Filter "ProcessId=${pid}").CommandLine`]);
      return /server\.js/i.test(out) && !!out;
    }
    const cmd = await runCmd('ps', ['-p', String(pid), '-o', 'command=']);
    if (!/server\.js/i.test(cmd)) return false;
    const cwdOut = await runCmd('lsof', ['-a', '-p', String(pid), '-d', 'cwd', '-Fn']);
    const cwdLine = cwdOut.split('\n').find((l) => l.startsWith('n')) || '';
    const cwdPath = cwdLine.slice(1);
    return !cwdPath || cwdPath === __dirname || cwdPath.startsWith(__dirname + path.sep) || cmd.includes(__dirname);
  } catch {
    return false;
  }
}

/** 端口被占时，自动退出本项目遗留的旧实例并等待端口释放 */
async function reclaimPortFromStaleInstance(port) {
  const pids = await pidsListeningOnPort(port);
  let killedAny = false;
  for (const pid of pids) {
    if (pid === process.pid) continue;
    if (!(await isOurServerProcess(pid))) continue;
    try {
      process.kill(pid, 'SIGTERM');
      killedAny = true;
      console.log(`已自动退出旧实例（PID ${pid}），正在重新启动...`);
    } catch { /* 无权限等，忽略 */ }
  }
  if (!killedAny) return false;
  for (let i = 0; i < 20; i++) {
    await new Promise((r) => setTimeout(r, 200));
    if (!(await pidsListeningOnPort(port)).length) return true;
  }
  // SIGTERM 没退干净 → 强杀兜底
  for (const pid of await pidsListeningOnPort(port)) {
    try { process.kill(pid, 'SIGKILL'); } catch { /* ignore */ }
  }
  await new Promise((r) => setTimeout(r, 400));
  return !(await pidsListeningOnPort(port)).length;
}

function printPortBusyHelp() {
  console.error(`启动失败：端口 ${LISTEN_PORT} 已被其他程序占用（非本工具实例），无法自动处理。`);
  console.error('可任选其一：');
  console.error(`  · 退出占用该端口的程序：macOS/Linux 执行 lsof -ti tcp:${LISTEN_PORT} 查 PID，Windows 执行 netstat -ano | findstr :${LISTEN_PORT}`);
  console.error(`  · 或修改 config.json 里的 port（或以 PORT=xxxx 环境变量临时指定）后再启动。`);
}

let listenAttempts = 0;
const MAX_LISTEN_ATTEMPTS = 3;

server.on('error', async (err) => {
  if (err && err.code === 'EADDRINUSE' && listenAttempts < MAX_LISTEN_ATTEMPTS) {
    listenAttempts += 1;
    console.log(`端口 ${LISTEN_PORT} 被占用，正在检测是否为本工具的旧实例...`);
    let reclaimed = false;
    try {
      reclaimed = await reclaimPortFromStaleInstance(LISTEN_PORT);
    } catch { /* 检测失败按未回收处理 */ }
    if (reclaimed) {
      server.listen(LISTEN_PORT, HOST);
      return;
    }
    printPortBusyHelp();
    process.exit(1);
  }
  if (err && err.code === 'EADDRINUSE') {
    printPortBusyHelp();
    process.exit(1);
  }
  throw err;
});

server.listen(LISTEN_PORT, HOST, () => {
  const url = `http://${HOST === '0.0.0.0' ? 'localhost' : HOST}:${LISTEN_PORT}`;
  ctx.logs.pushSystemLog(`服务已启动：${url}`, 'success');
  console.log(`智慧运营中台已启动: ${url}`);
  // "start" is a cmd.exe builtin (not a standalone executable), so it must be run via cmd /c;
  // the empty "" argument is the window-title placeholder start expects before the URL.
  execFile('cmd', ['/c', 'start', '', url], () => {});
});

// ---------- 优雅停机：Ctrl+C / kill 时先落盘任务与采集状态，再退出 ----------
let shuttingDown = false;
function shutdown(signal) {
  if (shuttingDown) { process.exit(1); } // 连按两次 Ctrl+C 强制退出
  shuttingDown = true;
  console.log(`\n收到 ${signal}，正在保存状态并退出...`);
  try { ctx.generation.flushPersisted(); } catch { /* ignore */ }
  try { ctx.crawl.flushState(); } catch { /* ignore */ }
  try { if (server.closeIdleConnections) server.closeIdleConnections(); } catch { /* ignore */ }
  server.close(() => process.exit(0));
  setTimeout(() => process.exit(0), 3000).unref();
}
process.on('SIGTERM', () => shutdown('SIGTERM'));
process.on('SIGINT', () => shutdown('SIGINT'));