let serverTime = null;
let timeDiff = 0;
// 獲取服務(wù)器時(shí)間
fetch('/api/server-time')
  .then(response => response.json())
  .then(data => {
    serverTime = new Date(data.time);
    timeDiff = serverTime.getTime() - Date.now();
    startCountdown();
  });
// 定期校準(zhǔn)
setInterval(() => {
  fetch('/api/server-time')
    .then(response => response.json())
    .then(data => {
      serverTime = new Date(data.time);
      timeDiff = serverTime.getTime() - Date.now();
    });
}, 60000); // 每分鐘校準(zhǔn)一次
// 開始倒計(jì)時(shí)
function startCountdown() {
  const countdownTime = serverTime.getTime() + timeDiff + 10 * 60 * 1000; // 假設(shè)倒計(jì)時(shí)為10分鐘
  const timer = setInterval(() => {
    const now = Date.now() + timeDiff;
    const remainingTime = countdownTime - now;
    if (remainingTime > 0) {
      const minutes = Math.floor(remainingTime / 60000);
      const seconds = Math.floor((remainingTime % 60000) / 1000);
      console.log(`${minutes}分${seconds}秒`);
    } else {
      console.log('倒計(jì)時(shí)結(jié)束');
      clearInterval(timer);
    }
  }, 1000);
}

// 主線程
const worker = new Worker('countdown.worker.js');
worker.onmessage = function(e) {
  console.log('倒計(jì)時(shí)剩余時(shí)間：' + e.data);
};
worker.postMessage(10); // 10秒倒計(jì)時(shí)
// countdown.worker.js (Web Worker文件)
self.onmessage = function(e) {
  let count = e.data;
  const timer = setInterval(function() {
    count--;
    self.postMessage(count);
    if (count === 0) {
      clearInterval(timer);
    }
  }, 1000);
};

let firstStamp = null; // 倒計(jì)時(shí)開始的時(shí)間戳
let lastStamp = null;  // 上一次更新的時(shí)間戳
let timer = null;      // 定時(shí)器
let total = 10;        // 倒計(jì)時(shí)總時(shí)間（10秒）
// 監(jiān)聽頁面可見性變化
document.addEventListener('visibilitychange', handleVisibilityChange);
// 頁面可見性變化處理函數(shù)
function handleVisibilityChange() {
    // 當(dāng)頁面變?yōu)榭梢姞顟B(tài)時(shí)，修正倒計(jì)時(shí)
    if (document.visibilityState === 'visible') {
        updateCount();
    }
}
// 開始倒計(jì)時(shí)
function startCountdown() {
    firstStamp = Date.now(); // 記錄倒計(jì)時(shí)開始的時(shí)間戳
    lastStamp = firstStamp;
    updateCount(); // 初始化倒計(jì)時(shí)顯示
}
// 更新倒計(jì)時(shí)
function updateCount() {
    clearTimeout(timer); // 清除舊的定時(shí)器
    const nowStamp = Date.now(); // 當(dāng)前時(shí)間戳
    const pastTime = nowStamp - firstStamp; // 已經(jīng)過的時(shí)間
    const remainTime = total * 1000 - pastTime; // 剩余時(shí)間
    if (remainTime > 0) {
        // 更新倒計(jì)時(shí)顯示
        const seconds = Math.floor(remainTime / 1000);
        console.log(`剩余時(shí)間：${seconds}秒`);
        lastStamp = nowStamp; // 更新上一次更新的時(shí)間戳
        // 設(shè)置新的定時(shí)器，確保下次定時(shí)器在剩余時(shí)間的基礎(chǔ)上執(zhí)行
        timer = setTimeout(updateCount, remainTime % 1000);
    } else {
        console.log('倒計(jì)時(shí)結(jié)束');
    }
}
// 啟動倒計(jì)時(shí)
startCountdown();

function accurateTimer(fn, interval) {
  let expected = Date.now() + interval;
  let timeout;
  const tick = () => {
    const drift = Date.now() - expected; // 計(jì)算偏差
    fn();
    expected += interval; // 更新下次預(yù)期時(shí)間
    timeout = setTimeout(tick, Math.max(0, interval - drift));
  };
  timeout = setTimeout(tick, interval);
  return () => clearTimeout(timeout);
}
// 使用示例
let count = 10;
const stopTimer = accurateTimer(() => {
  count--;
  console.log(count);
  if (count === 0) {
    stopTimer();
  }
}, 1000);

let startTime = performance.now();
const totalDuration = 10000; // 10秒倒計(jì)時(shí)
const countDown = () => {
  const elapsedTime = performance.now() - startTime;
  const remainingTime = totalDuration - elapsedTime;
  if (remainingTime > 0) {
    console.log(Math.floor(remainingTime / 1000));
    requestAnimationFrame(countDown);
  } else {
    console.log('倒計(jì)時(shí)結(jié)束');
  }
};
requestAnimationFrame(countDown);