const fs = require('fs').promises;
async function loadConfigs() {
  const [db, redis, secrets] = await Promise.all([
    fs.readFile('./config/db.json', 'utf8').then(JSON.parse),
    fs.readFile('./config/redis.json', 'utf8').then(JSON.parse),
    fs.readFile('./config/secrets.json', 'utf8').then(JSON.parse)
  ]);
  console.log('所有配置加載完成', { db, redis, secrets });
}

async function syncUserToExternal(user) {
  const tasks = [
    syncToCRM(user),
    syncToEmailService(user),
    syncToPushService(user)
  ];
  const results = await Promise.allSettled(tasks);
  const failed = results.filter(r => r.status === 'rejected');
  if (failed.length) {
    console.error(`同步失敗 ${failed.length} 個(gè)系統(tǒng)`, failed.map(f => f.reason));
    // 將失敗記錄到數(shù)據(jù)庫(kù)，等待重試隊(duì)列處理
  }
  return results;
}

function fetchWithTimeout(url, timeout = 3000) {
  const controller = new AbortController();
  const fetchPromise = fetch(url, { signal: controller.signal });
  const timeoutPromise = new Promise((_, reject) =>
    setTimeout(() => {
      controller.abort();
      reject(new Error('請(qǐng)求超時(shí)'));
    }, timeout)
  );
  return Promise.race([fetchPromise, timeoutPromise]);
}
// 使用
try {
  const data = await fetchWithTimeout('https://slow-api.example.com/data', 3000);
  console.log(data);
} catch (err) {
  console.log('使用緩存數(shù)據(jù)');
}

async function loadScriptFromCDNs(urls) {
  const fetchTasks = urls.map(url => fetch(url).then(res => {
    if (!res.ok) throw new Error(`HTTP ${res.status}`);
    return res.text();
  }));
  try {
    const scriptContent = await Promise.any(fetchTasks);
    eval(scriptContent); // 實(shí)際項(xiàng)目中建議使用更安全的方式
    console.log('腳本加載成功');
  } catch (aggregateError) {
    console.error('所有 CDN 均不可用', aggregateError.errors);
  }
}
loadScriptFromCDNs([
  'https://cdn1.example.com/lib.js',
  'https://cdn2.example.com/lib.js',
  'https://cdn3.example.com/lib.js'
]);

const EventEmitter = require('events');
const fs = require('fs');
class FileWriter extends EventEmitter {
  writeAndNotify(file, data) {
    fs.writeFile(file, data, (err) => {
      if (err) this.emit('error', err);
      else this.emit('done', file);
    });
  }
}
// 應(yīng)用
const writer = new FileWriter();
let completed = 0;
const total = 3;
function onAllDone() {
  console.log('所有文件寫(xiě)入完成，開(kāi)始合并壓縮');
  // 執(zhí)行合并邏輯
}
writer.on('done', (file) => {
  console.log(`${file} 寫(xiě)入完成`);
  if (++completed === total) onAllDone();
});
writer.writeAndNotify('log1.txt', 'data1');
writer.writeAndNotify('log2.txt', 'data2');
writer.writeAndNotify('log3.txt', 'data3');

const { fromEvent, merge, bufferCount } = require('rxjs');
const { EventEmitter } = require('events');
const sensorA = new EventEmitter();
const sensorB = new EventEmitter();
const sensorC = new EventEmitter();
// 模擬每秒推送一次數(shù)據(jù)
setInterval(() => sensorA.emit('data', Math.random() * 30), 1000);
setInterval(() => sensorB.emit('data', Math.random() * 60), 1000);
setInterval(() => sensorC.emit('data', Math.random() * 10), 1000);
// 將 EventEmitter 轉(zhuǎn)為 Observable
const streamA = fromEvent(sensorA, 'data');
const streamB = fromEvent(sensorB, 'data');
const streamC = fromEvent(sensorC, 'data');
// 合并并每收到3個(gè)值（各一個(gè)）計(jì)算一次平均值
merge(streamA, streamB, streamC)
  .pipe(bufferCount(3))
  .subscribe(values => {
    const avg = values.reduce((a, b) => a + b, 0) / values.length;
    console.log(`實(shí)時(shí)平均傳感器值: ${avg.toFixed(2)}`);
  });

const pLimit = require('p-limit');
const fs = require('fs').promises;
const path = require('path');
async function uploadFile(filePath) {
  console.log(`開(kāi)始上傳 ${path.basename(filePath)}`);
  await new Promise(r => setTimeout(r, 1000)); // 模擬上傳
  console.log(`完成上傳 ${path.basename(filePath)}`);
  return filePath;
}
async function uploadAll(filePaths) {
  const limit = pLimit(5); // 最多5個(gè)并發(fā)
  const tasks = filePaths.map(filePath => 
    limit(() => uploadFile(filePath))
  );
  const results = await Promise.all(tasks);
  console.log(`全部上傳完成，共 ${results.length} 個(gè)文件`);
}
// 生成100個(gè)測(cè)試文件路徑
const files = Array.from({ length: 100 }, (_, i) => `/tmp/file${i}.txt`);
uploadAll(files);