// ==UserScript==
// @name         Auto Translate Pro
// @namespace    auto-translate-pro
// @version      3.0.0
// @description  自动检测设备语言，翻译网页内容并直接替换，支持双语对照，多引擎切换
// @match        *://*/*
// @grant        GM_xmlhttpRequest
// @grant        GM_getValue
// @grant        GM_setValue
// @grant        GM_addStyle
// @grant        GM_registerMenuCommand
// @connect      translate.googleapis.com
// @connect      api-edge.cognitive.microsofttranslator.com
// @connect      edge.microsoft.com
// @connect      transmart.qq.com
// @connect      fanyi.sogou.com
// @connect      ifanyi.iciba.com
// @connect      m.youdao.com
// @connect      api.interpreter.caiyunai.com
// @connect      fanyi.caiyunapp.com
// @connect      translate.alibaba.com
// @connect      papago.naver.com
// @connect      www2.deepl.com
// @connect      fanyi.baidu.com
// @connect      translate.yandex.net
// @connect      translate.yandex.com
// @connect      fanyi.pdf365.cn
// @connect      *
// @run-at       document-idle
// @downloadURL none
// ==/UserScript==

(async () => {
  'use strict';

  // ═══════════════════════════════════════════════════════════════════
  //
  // 形式化规约 (Coq-style Specification)
  //
  // ── 类型定义 ──
  // TextNode    := DOM Text Node with textContent.trim().length > 0
  // TransUnit   := { node: TextNode, original: string, translated: string | null }
  // EngineSpec  := { name: string, translate: string → string → Promise<string> }
  // Mode        := Idle | Translating | Replaced | Bilingual
  // State       := { mode: Mode, units: Map<Node, TransUnit>, cache: Map<string, string> }
  //
  // ── 不变量 ──
  // I₁ (标记一致性):
  //   ∀ el ∈ DOM, el.dataset.translated = '1'
  //     ⟹ el.dataset.origText ∈ string ∧ el.dataset.origText = 翻译前文本
  //
  // I₂ (缓存纯函数):
  //   ∀ (k, v) ∈ cache, engine.translate(k, lang) = v
  //   即缓存是翻译函数的记忆化
  //
  // I₃ (幂等性):
  //   translatePage ∘ translatePage ≡ translatePage
  //   通过 data-translated 守卫实现
  //
  // I₄ (可逆性):
  //   restorePage ∘ translatePage ≡ id
  //   翻译前状态完整保存，还原精确恢复
  //
  // I₅ (双语同构):
  //   bilingualMode = true ⟹
  //     ∀ translated node, ∃ (span.bt-s, span.bt-d) ∈ node.children
  //     s.t. bt-s.text = original ∧ bt-d.text = translated
  //
  // I₆ (完备性):
  //   ∀ visible text node n ∈ DOM,
  //     ¬isTargetLang(n.text) ∧ ¬isSkipped(n.parent)
  //     ⟹ n ∈ translatePage 的处理范围
  //
  // ── 状态转移 ──
  //   Idle          →[translate]→      Translating
  //   Translating   →[complete]→       Replaced | Bilingual
  //   Replaced      →[restore]→        Idle
  //   Replaced      →[toggleBi]→       Bilingual
  //   Bilingual     →[toggleBi]→       Replaced
  //   Bilingual     →[restore]→        Idle
  //   *             →[switchEngine]→   Idle → Translating (自动重翻)
  //   *             →[switchLang]→     Idle → Translating (自动重翻)
  //
  // ═══════════════════════════════════════════════════════════════════

  try { if (document.contentType === 'application/xml') return; } catch (_) {}

  // ════════════════════════════
  //  常量
  // ════════════════════════════
  const BATCH_SIZE       = 25;
  const CONCURRENCY      = 5;
  const SCROLL_DEBOUNCE  = 500;
  const MUTATION_DEBOUNCE = 700;
  const STARTUP_DELAY    = 1000;
  const TOKEN_TTL        = 480000;
  const MAX_CACHE        = 4000;
  const MAX_TEXT_LEN     = 5000;
  const MIN_TEXT_LEN     = 1;

  // ════════════════════════════
  //  工具函数
  // ════════════════════════════
  const deviceLang = (() => {
    const raw = navigator.language || navigator.userLanguage || 'zh-CN';
    return raw.split('-')[0].toLowerCase();
  })();

  function gmFetch(opts) {
    return new Promise((resolve, reject) => {
      GM_xmlhttpRequest({
        timeout: 20000,
        ...opts,
        onload: resolve,
        onerror: reject,
        ontimeout: reject,
      });
    });
  }

  function uuid() {
    if (typeof crypto !== 'undefined' && crypto.randomUUID) return crypto.randomUUID();
    return 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, c => {
      const r = Math.random() * 16 | 0;
      return (c === 'x' ? r : (r & 0x3 | 0x8)).toString(16);
    });
  }

  function sleep(ms) { return new Promise(r => setTimeout(r, ms)); }

  // MD5 极简实现 (用于搜狗/词霸等签名)
  // 生产环境应使用完整实现，这里提供核心功能
  function md5(string) {
    function md5cycle(x, k) {
      let a = x[0], b = x[1], c = x[2], d = x[3];
      a = ff(a, b, c, d, k[0], 7, -680876936);d = ff(d, a, b, c, k[1], 12, -389564586);c = ff(c, d, a, b, k[2], 17, 606105819);b = ff(b, c, d, a, k[3], 22, -1044525330);
      a = ff(a, b, c, d, k[4], 7, -176418897);d = ff(d, a, b, c, k[5], 12, 1200080426);c = ff(c, d, a, b, k[6], 17, -1473231341);b = ff(b, c, d, a, k[7], 22, -45705983);
      a = ff(a, b, c, d, k[8], 7, 1770035416);d = ff(d, a, b, c, k[9], 12, -1958414417);c = ff(c, d, a, b, k[10], 17, -42063);b = ff(b, c, d, a, k[11], 22, -1990404162);
      a = ff(a, b, c, d, k[12], 7, 1804603682);d = ff(d, a, b, c, k[13], 12, -40341101);c = ff(c, d, a, b, k[14], 17, -1502002290);b = ff(b, c, d, a, k[15], 22, 1236535329);
      a = gg(a, b, c, d, k[1], 5, -165796510);d = gg(d, a, b, c, k[6], 9, -1069501632);c = gg(c, d, a, b, k[11], 14, 643717713);b = gg(b, c, d, a, k[0], 20, -373897302);
      a = gg(a, b, c, d, k[5], 5, -701558691);d = gg(d, a, b, c, k[10], 9, 38016083);c = gg(c, d, a, b, k[15], 14, -660478335);b = gg(b, c, d, a, k[4], 20, -405537848);
      a = gg(a, b, c, d, k[9], 5, 568446438);d = gg(d, a, b, c, k[14], 9, -1019803690);c = gg(c, d, a, b, k[3], 14, -187363961);b = gg(b, c, d, a, k[8], 20, 1163531501);
      a = gg(a, b, c, d, k[13], 5, -1444681467);d = gg(d, a, b, c, k[2], 9, -51403784);c = gg(c, d, a, b, k[7], 14, 1735328473);b = gg(b, c, d, a, k[12], 20, -1926607734);
      a = hh(a, b, c, d, k[5], 4, -378558);d = hh(d, a, b, c, k[8], 11, -2022574463);c = hh(c, d, a, b, k[11], 16, 1839030562);b = hh(b, c, d, a, k[14], 23, -35309556);
      a = hh(a, b, c, d, k[1], 4, -1530992060);d = hh(d, a, b, c, k[4], 11, 1272893353);c = hh(c, d, a, b, k[7], 16, -155497632);b = hh(b, c, d, a, k[10], 23, -1094730640);
      a = hh(a, b, c, d, k[13], 4, 681279174);d = hh(d, a, b, c, k[0], 11, -358537222);c = hh(c, d, a, b, k[3], 16, -722521979);b = hh(b, c, d, a, k[6], 23, 76029189);
      a = hh(a, b, c, d, k[9], 4, -640364487);d = hh(d, a, b, c, k[12], 11, -421815835);c = hh(c, d, a, b, k[15], 16, 530742520);b = hh(b, c, d, a, k[2], 23, -995338651);
      a = ii(a, b, c, d, k[0], 6, -198630844);d = ii(d, a, b, c, k[7], 10, 1126891415);c = ii(c, d, a, b, k[14], 15, -1416354905);b = ii(b, c, d, a, k[5], 21, -57434055);
      a = ii(a, b, c, d, k[12], 6, 1700485571);d = ii(d, a, b, c, k[3], 10, -1894986606);c = ii(c, d, a, b, k[10], 15, -1051523);b = ii(b, c, d, a, k[1], 21, -2054922799);
      a = ii(a, b, c, d, k[8], 6, 1873313359);d = ii(d, a, b, c, k[15], 10, -30611744);c = ii(c, d, a, b, k[6], 15, -1560198380);b = ii(b, c, d, a, k[13], 21, 1309151649);
      a = ii(a, b, c, d, k[4], 6, -145523070);d = ii(d, a, b, c, k[11], 10, -1120210379);c = ii(c, d, a, b, k[2], 15, 718787259);b = ii(b, c, d, a, k[9], 21, -343485551);
      x[0] = add32(a, x[0]);x[1] = add32(b, x[1]);x[2] = add32(c, x[2]);x[3] = add32(d, x[3]);
    }
    function cmn(q, a, b, x, s, t) { a = add32(add32(a, q), add32(x, t)); return add32((a << s) | (a >>> (32 - s)), b); }
    function ff(a, b, c, d, x, s, t) { return cmn((b & c) | ((~b) & d), a, b, x, s, t); }
    function gg(a, b, c, d, x, s, t) { return cmn((b & d) | (c & (~d)), a, b, x, s, t); }
    function hh(a, b, c, d, x, s, t) { return cmn(b ^ c ^ d, a, b, x, s, t); }
    function ii(a, b, c, d, x, s, t) { return cmn(c ^ (b | (~d)), a, b, x, s, t); }
    function md51(s) {
      let n = s.length, state = [1732584193, -271733879, -1732584194, 271733878], i;
      for (i = 64; i <= n; i += 64) md5cycle(state, md5blk(s.substring(i - 64, i)));
      s = s.substring(i - 64);
      let tail = [0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0];
      for (i = 0; i < s.length; i++) tail[i >> 2] |= s.charCodeAt(i) << ((i % 4) << 3);
      tail[i >> 2] |= 0x80 << ((i % 4) << 3);
      if (i > 55) { md5cycle(state, tail); tail = [0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]; }
      tail[14] = n * 8;
      md5cycle(state, tail);
      return state;
    }
    function md5blk(s) {
      let md5blks = [], i;
      for (i = 0; i < 64; i += 4) md5blks[i >> 2] = s.charCodeAt(i) + (s.charCodeAt(i+1) << 8) + (s.charCodeAt(i+2) << 16) + (s.charCodeAt(i+3) << 24);
      return md5blks;
    }
    function rhex(n) {
      let s = '', j;
      for (j = 0; j < 4; j++) s += ('0' + ((n >> (j * 8 + 4)) & 0x0F).toString(16) + (n >> (j * 8) & 0x0F).toString(16));
      return s;
    }
    function hex(x) { for (let i = 0; i < x.length; i++) x[i] = rhex(x[i]); return x.join(''); }
    function add32(a, b) { return (a + b) & 0xFFFFFFFF; }
    if (typeof string !== 'string') string = String(string);
    return hex(md51(unescape(encodeURIComponent(string))));
  }


  // ════════════════════════════
  //  翻译引擎注册表
  // ════════════════════════════
  //
  // 每个引擎满足接口契约:
  //   name: string                              — 显示名
  //   needsAuth: boolean                        — 是否需要预鉴权
  //   auth(): Promise<void>                     — 鉴权 (needsAuth=true时调用)
  //   langCode(baseLang: string): string        — 将基础语言码映射为引擎语言码
  //   translate(text, toLang): Promise<string>  — 翻译单条
  //   supportsBatch: boolean                    — 是否支持原生批量
  //   translateBatch?(texts, toLang): Promise<string[]>  — 批量翻译
  //

  const Engine = {};

  // ── Google ──
  Engine.google = {
    name: 'Google',
    needsAuth: false,
    supportsBatch: false,
    langCode(lang) {
      const m = { zh:'zh-CN',en:'en',ja:'ja',ko:'ko',fr:'fr',de:'de',es:'es',ru:'ru',pt:'pt',ar:'ar',
        th:'th',vi:'vi',it:'it',tr:'tr',id:'id',hi:'hi',nl:'nl',pl:'pl',uk:'uk',cs:'cs',
        sv:'sv',da:'da',fi:'fi',el:'el',ro:'ro',hu:'hu',nb:'no',ms:'ms',tl:'tl' };
      return m[lang] || lang;
    },
    async translate(text, toLang) {
      const to = this.langCode(toLang);
      const r = await gmFetch({
        method: 'GET',
        url: `https://translate.googleapis.com/translate_a/single?client=gtx&dt=t&sl=auto&tl=${to}&q=${encodeURIComponent(text)}`,
      });
      if (r.status !== 200) throw new Error(`Google ${r.status}`);
      const d = JSON.parse(r.responseText);
      return d[0].map(s => s[0]).join('');
    }
  };

  // ── Microsoft ──
  Engine.microsoft = {
    name: 'Microsoft',
    needsAuth: true,
    supportsBatch: true,
    _token: null,
    _tokenTime: 0,
    async auth() {
      if (this._token && Date.now() - this._tokenTime < TOKEN_TTL) return;
      const r = await gmFetch({ method: 'GET', url: 'https://edge.microsoft.com/translate/auth' });
      if (r.status !== 200) throw new Error(`MS auth ${r.status}`);
      this._token = r.responseText;
      this._tokenTime = Date.now();
    },
    langCode(lang) {
      const m = { zh:'zh-Hans',en:'en',ja:'ja',ko:'ko',fr:'fr',de:'de',es:'es',ru:'ru',pt:'pt',ar:'ar',
        th:'th',vi:'vi',it:'it',tr:'tr',id:'id',hi:'hi',nl:'nl',pl:'pl',uk:'uk',cs:'cs',
        sv:'sv',da:'da',fi:'fi',el:'el',ro:'ro',hu:'hu',nb:'nb',ms:'ms',tl:'fil' };
      return m[lang] || lang;
    },
    async translate(text, toLang) {
      await this.auth();
      const to = this.langCode(toLang);
      const r = await gmFetch({
        method: 'POST',
        url: `https://api-edge.cognitive.microsofttranslator.com/translate?from=&to=${to}&api-version=3.0`,
        headers: { 'authorization': `Bearer ${this._token}`, 'Content-Type': 'application/json' },
        data: JSON.stringify([{ Text: text }]),
      });
      if (r.status !== 200) throw new Error(`MS ${r.status}`);
      return JSON.parse(r.responseText)[0].translations[0].text;
    },
    async translateBatch(texts, toLang) {
      await this.auth();
      const to = this.langCode(toLang);
      const all = [];
      for (let i = 0; i < texts.length; i += BATCH_SIZE) {
        const chunk = texts.slice(i, i + BATCH_SIZE);
        try {
          const r = await gmFetch({
            method: 'POST',
            url: `https://api-edge.cognitive.microsofttranslator.com/translate?from=&to=${to}&api-version=3.0`,
            headers: { 'authorization': `Bearer ${this._token}`, 'Content-Type': 'application/json' },
            data: JSON.stringify(chunk.map(t => ({ Text: t }))),
          });
          if (r.status === 200) {
            const data = JSON.parse(r.responseText);
            for (const item of data) all.push(item.translations[0].text);
          } else {
            for (let j = 0; j < chunk.length; j++) all.push(null);
          }
        } catch (_) {
          for (let j = 0; j < chunk.length; j++) all.push(null);
        }
      }
      return all;
    }
  };

  // ── Tencent (腾讯交互) ──
  Engine.tencent = {
    name: 'Tencent',
    needsAuth: false,
    supportsBatch: false,
    _clientKey: null,
    langCode(lang) {
      const m = { zh:'zh',en:'en',ja:'ja',ko:'ko',fr:'fr',de:'de',es:'es',ru:'ru',pt:'pt',ar:'ar',
        th:'th',vi:'vi',it:'it',tr:'tr',id:'id' };
      return m[lang] || lang;
    },
    async translate(text, toLang) {
      if (!this._clientKey) this._clientKey = `browser-chrome-120.0-${uuid()}-${Date.now()}`;
      const to = this.langCode(toLang);
      const r = await gmFetch({
        method: 'POST',
        url: 'https://transmart.qq.com/api/imt',
        headers: { 'Content-Type':'application/json','Origin':'https://transmart.qq.com','Referer':'https://transmart.qq.com/' },
        data: JSON.stringify({
          header:{ fn:'auto_translation',session:'',client_key:this._clientKey,user:'' },
          type:'plain',model_category:'normal',text_domain:'general',
          source:{ lang:'auto',text_list:[text] },
          target:{ lang:to }
        }),
      });
      if (r.status !== 200) throw new Error(`Tencent ${r.status}`);
      return JSON.parse(r.responseText).auto_translation[0];
    }
  };

  // ── DeepL (Web) ──
  Engine.deepl = {
    name: 'DeepL',
    needsAuth: false,
    supportsBatch: false,
    langCode(lang) {
      const m = { zh:'ZH',en:'EN',ja:'JA',ko:'KO',fr:'FR',de:'DE',es:'ES',ru:'RU',pt:'PT',
        it:'IT',tr:'TR',nl:'NL',pl:'PL',cs:'CS',da:'DA',fi:'FI',el:'EL',ro:'RO',hu:'HU',sv:'SV',id:'ID' };
      return m[lang] || lang.toUpperCase();
    },
    async translate(text, toLang) {
      const to = this.langCode(toLang);
      const from = 'auto';
      const id = Math.floor(Math.random() * 100000) + 1;
      const ts = Date.now();
      const iCount = (text.match(/i/g) || []).length + 1;
      const body = {
        jsonrpc:'2.0', method:'LMT_handle_jobs', id,
        params:{
          jobs:[{ kind:'default', sentences:[{ text, id:0, prefix:'' }],
            raw_en_context_before:[], raw_en_context_after:[],
            preferred_num_beams:4, quality:'fast' }],
          lang:{ preference:{ weight:{}, default:'default' },
            source_lang_user_selected:from, target_lang:to },
          priority:-1,
          commonJobParams:{ mode:'translate', browserType:1 },
          timestamp: ts + (iCount - ts % iCount)
        }
      };
      let payload = JSON.stringify(body);
      if ((id + 3) % 13 === 0 || (id + 5) % 29 === 0) {
        payload = payload.replace('"method":"', '"method" : "');
      }
      const r = await gmFetch({
        method:'POST',
        url:'https://www2.deepl.com/jsonrpc?method=LMT_handle_jobs',
        headers:{ 'Content-Type':'application/json','Origin':'https://www.deepl.com','Referer':'https://www.deepl.com/' },
        anonymous: true,
        data: payload,
      });
      if (r.status !== 200) throw new Error(`DeepL ${r.status}`);
      return JSON.parse(r.responseText).result.translations[0].beams[0].sentences[0].text;
    }
  };

  // ── Alibaba ──
  Engine.alibaba = {
    name: 'Alibaba',
    needsAuth: true,
    supportsBatch: false,
    _csrf: null,
    _boundary: null,
    async auth() {
      if (this._csrf) return;
      const r = await gmFetch({ method:'GET', url:'https://translate.alibaba.com/api/translate/csrftoken' });
      if (r.status === 200) {
        this._csrf = JSON.parse(r.responseText).token;
        this._boundary = Array.from({length:16}, () => 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789'[Math.random()*62|0]).join('');
      } else throw new Error(`Alibaba auth ${r.status}`);
    },
    langCode(lang) {
      const m = { zh:'zh',en:'en',ja:'ja',ko:'ko',fr:'fr',de:'de',es:'es',ru:'ru',pt:'pt',ar:'ar',
        th:'th',vi:'vi',it:'it',tr:'tr',id:'id' };
      return m[lang] || lang;
    },
    async translate(text, toLang) {
      await this.auth();
      const to = this.langCode(toLang);
      const b = this._boundary;
      const body = `------WebKitFormBoundary${b}\r\nContent-Disposition: form-data; name="srcLang"\r\n\r\nauto\r\n------WebKitFormBoundary${b}\r\nContent-Disposition: form-data; name="tgtLang"\r\n\r\n${to}\r\n------WebKitFormBoundary${b}\r\nContent-Disposition: form-data; name="domain"\r\n\r\ngeneral\r\n------WebKitFormBoundary${b}\r\nContent-Disposition: form-data; name="query"\r\n\r\n${text}\r\n------WebKitFormBoundary${b}\r\nContent-Disposition: form-data; name="_csrf"\r\n\r\n${this._csrf}\r\n------WebKitFormBoundary${b}--\r\n`;
      const r = await gmFetch({
        method:'POST', url:'https://translate.alibaba.com/api/translate/text',
        headers:{
          'content-type':`multipart/form-data; boundary=----WebKitFormBoundary${b}`,
          'accept':'application/json, text/plain, */*',
          'Origin':'https://translate.alibaba.com','Referer':'https://translate.alibaba.com/',
          'x-xsrf-token_property_item': this._csrf,
        },
        data: body,
      });
      if (r.status !== 200) throw new Error(`Alibaba ${r.status}`);
      return JSON.parse(r.responseText).data.translateText;
    }
  };

  // ── Papago ──
  Engine.papago = {
    name: 'Papago',
    needsAuth: false,
    supportsBatch: false,
    _id: null,
    langCode(lang) {
      const m = { zh:'zh-CN',en:'en',ja:'ja',ko:'ko',fr:'fr',de:'de',es:'es',ru:'ru',pt:'pt',
        th:'th',vi:'vi',it:'it',tr:'tr',id:'id' };
      return m[lang] || lang;
    },
    _hmacMd5(key, message) {
      // 简易 HMAC-MD5
      const blockSize = 64;
      let keyBytes = key;
      if (keyBytes.length > blockSize) keyBytes = md5(keyBytes);
      while (keyBytes.length < blockSize) keyBytes += '\0';
      let opad = '', ipad = '';
      for (let i = 0; i < blockSize; i++) {
        const b = keyBytes.charCodeAt(i);
        opad += String.fromCharCode(b ^ 0x5c);
        ipad += String.fromCharCode(b ^ 0x36);
      }
      const inner = md5(ipad + message);
      // md5 returns hex, need to convert back to binary for outer
      let innerBin = '';
      for (let i = 0; i < inner.length; i += 2) innerBin += String.fromCharCode(parseInt(inner.substr(i, 2), 16));
      return md5(opad + innerBin);
    },
    async translate(text, toLang) {
      if (!this._id) this._id = uuid();
      const to = this.langCode(toLang);
      const ts = Date.now() - 1073;
      const msg = `${this._id}\nhttps://papago.naver.com/apis/nsmt/translate\n${ts}`;
      const auth = 'PPG ' + this._id + ':' + btoa(this._hmacMd5('v1.8.12_7cf22c1499', msg));
      const r = await gmFetch({
        method:'POST', url:'https://papago.naver.com/apis/nsmt/translate',
        headers:{
          'Origin':'https://papago.naver.com','Referer':'https://papago.naver.com/',
          'accept':'application/json','content-type':'application/x-www-form-urlencoded; charset=UTF-8',
          'Device-Type':'pc','Timestamp':`${ts}`,'Authorization': auth,
        },
        data:`deviceId=${this._id}&locale=zh-CN&dict=true&dictDisplay=30&honorific=false&instant=false&paging=false&source=auto&target=${to}&text=${encodeURIComponent(text)}`,
      });
      if (r.status !== 200) throw new Error(`Papago ${r.status}`);
      return JSON.parse(r.responseText).translatedText;
    }
  };

  // ── 有道手机版 ──
  Engine.youdao = {
    name: 'Youdao',
    needsAuth: false,
    supportsBatch: false,
    langCode(lang) {
      const m = { zh:'ZH_CN',en:'EN',ja:'JA',ko:'KO',fr:'FR',de:'DE',es:'ES',ru:'RU',pt:'PT' };
      return m[lang] || lang.toUpperCase();
    },
    async translate(text, toLang) {
      const to = this.langCode(toLang);
      const r = await gmFetch({
        method:'POST', url:'https://m.youdao.com/translate',
        headers:{ 'Origin':'https://m.youdao.com','Referer':'https://m.youdao.com/translate/','Content-Type':'application/x-www-form-urlencoded' },
        data:`inputtext=${encodeURIComponent(text)}&type=AUTO2${to}`,
      });
      if (r.status !== 200) throw new Error(`Youdao ${r.status}`);
      const doc = document.implementation.createHTMLDocument();
      doc.body.innerHTML = r.responseText;
      const li = doc.querySelector('#translateResult li');
      return li ? li.innerText.trim() : null;
    }
  };

  // ── 彩云小译 ──
  Engine.caiyun = {
    name: 'Caiyun',
    needsAuth: true,
    supportsBatch: false,
    _token: null,
    _jwt: null,
    _deviceId: null,
    langCode(lang) {
      const m = { zh:'zh',en:'en',ja:'ja',ko:'ko',fr:'fr',de:'de',es:'es',ru:'ru' };
      return m[lang] || lang;
    },
    _rot13(str) {
      const a = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz';
      const b = 'NOPQRSTUVWXYZABCDEFGHIJKLMnopqrstuvwxyzabcdefghijklm';
      return str.split('').map(c => { const i = a.indexOf(c); return i > -1 ? b[i] : c; }).join('');
    },
    _decodeTarget(target) {
      try {
        const rotated = this._rot13(target);
        return decodeURIComponent(escape(atob(rotated)));
      } catch (_) { return target; }
    },
    async auth() {
      if (this._jwt && this._token) return;
      this._deviceId = this._deviceId || Array.from({length:32}, () => '0123456789abcdef'[Math.random()*16|0]).join('');
      // 获取页面提取token
      const pageRes = await gmFetch({ method:'GET', url:'https://fanyi.caiyunapp.com/' });
      if (pageRes.status !== 200) throw new Error('Caiyun page error');
      const jsMatch = /\/assets\/index\.(.*?)\.js/i.exec(pageRes.responseText);
      if (!jsMatch) throw new Error('Caiyun js not found');
      const jsRes = await gmFetch({ method:'GET', url:`https://fanyi.caiyunapp.com/dist${jsMatch[0]}` });
      if (jsRes.status !== 200) throw new Error('Caiyun js error');
      const tokenMatch = /token:"(.*?)"/i.exec(jsRes.responseText);
      if (!tokenMatch) throw new Error('Caiyun token not found');
      this._token = tokenMatch[1];
      // 获取JWT
      const jwtRes = await gmFetch({
        method:'POST', url:'https://api.interpreter.caiyunai.com/v1/user/jwt/generate',
        headers:{
          'accept':'application/json, text/plain, */*','content-type':'application/json;charset=UTF-8',
          'app-name':'xy','device-id':this._deviceId,'os-type':'web',
          'x-authorization':this._token,'origin':'https://fanyi.caiyunapp.com',
        },
        data: JSON.stringify({ browser_id: this._deviceId }),
      });
      if (jwtRes.status === 200) this._jwt = JSON.parse(jwtRes.responseText).jwt;
    },
    async translate(text, toLang) {
      await this.auth();
      if (!this._jwt) throw new Error('Caiyun no JWT');
      const to = this.langCode(toLang);
      const r = await gmFetch({
        method:'POST', url:'https://api.interpreter.caiyunai.com/v1/translator',
        headers:{
          'accept':'application/json, text/plain, */*','content-type':'application/json;charset=UTF-8',
          'app-name':'xiaoyi','device-id':this._deviceId,'os-type':'web',
          't-authorization':this._jwt,'x-authorization':this._token,
          'origin':'https://fanyi.caiyunapp.com',
        },
        data: JSON.stringify({
          source:text, trans_type:`auto2${to}`, request_id:'web_fanyi',
          media:'text', os_type:'web', dict:true, cached:true, replaced:true,
          style:'formal', browser_id:this._deviceId,
        }),
      });
      if (r.status !== 200) throw new Error(`Caiyun ${r.status}`);
      return this._decodeTarget(JSON.parse(r.responseText).target);
    }
  };

  // ── 百度手机版 ──
  Engine.baidu = {
    name: 'Baidu',
    needsAuth: true,
    supportsBatch: false,
    _token: null,
    _gtk: null,
    langCode(lang) {
      const m = { zh:'zh',en:'en',ja:'jp',ko:'kor',fr:'fra',de:'de',es:'spa',ru:'ru',pt:'pt',
        ar:'ara',th:'th',vi:'vie',it:'it',tr:'tr',id:'id' };
      return m[lang] || lang;
    },
    async auth() {
      if (this._token && this._gtk) return;
      const r = await gmFetch({
        method:'GET', url:'https://fanyi.baidu.com',
        headers:{ 'user-agent':'Mozilla/5.0 (Linux; Android 10) AppleWebKit/537.36 Chrome/120.0 Mobile Safari/537.36' },
      });
      if (r.status !== 200) throw new Error(`Baidu auth ${r.status}`);
      const tokenMatch = /token:\s*['"]([^'"]+)['"]/i.exec(r.responseText);
      const gtkMatch = /['"](\d{6}\.\d{9})['"]/i.exec(r.responseText);
      if (tokenMatch) this._token = tokenMatch[1];
      if (gtkMatch) this._gtk = gtkMatch[1];
      if (!this._token || !this._gtk) throw new Error('Baidu auth data not found');
    },
    _sign(text) {
      const gtk = this._gtk;
      const h = gtk.split('.');
      let f = Number(h[0]) || 0, m = Number(h[1]) || 0;
      let g = [], y = 0;
      for (let v = 0; v < text.length; v++) {
        let _ = text.charCodeAt(v);
        if (_ < 128) g[y++] = _;
        else if (_ < 2048) { g[y++] = _ >> 6 | 192; g[y++] = 63 & _ | 128; }
        else if (55296 === (64512 & _) && v + 1 < text.length && 56320 === (64512 & text.charCodeAt(v + 1))) {
          _ = 65536 + ((1023 & _) << 10) + (1023 & text.charCodeAt(++v));
          g[y++] = _ >> 18 | 240; g[y++] = _ >> 12 & 63 | 128; g[y++] = _ >> 6 & 63 | 128; g[y++] = 63 & _ | 128;
        } else { g[y++] = _ >> 12 | 224; g[y++] = _ >> 6 & 63 | 128; g[y++] = 63 & _ | 128; }
      }
      let b = f;
      const w = '+-a^+6', k = '+-3^+b+-f';
      function n(t, e) { for (let n = 0; n < e.length - 2; n += 3) { let r = e.charAt(n + 2); r = r >= 'a' ? r.charCodeAt(0) - 87 : Number(r); r = '+' === e.charAt(n + 1) ? t >>> r : t << r; t = '+' === e.charAt(n) ? t + r & 0xFFFFFFFF : t ^ r; } return t; }
      for (let x = 0; x < g.length; x++) b = n(b += g[x], w);
      b = n(b, k);
      b ^= m;
      if (b < 0) b = (2147483647 & b) + 2147483648;
      b %= 1e6;
      return `${b}.${b ^ f}`;
    },
    async translate(text, toLang) {
      await this.auth();
      const to = this.langCode(toLang);
      const r = await gmFetch({
        method:'POST', url:'https://fanyi.baidu.com/basetrans',
        headers:{
          'content-type':'application/x-www-form-urlencoded',
          'origin':'https://fanyi.baidu.com','referer':'https://fanyi.baidu.com/',
        },
        data:`query=${encodeURIComponent(text)}&from=auto&to=${to}&token=${this._token}&sign=${this._sign(text)}`,
      });
      if (r.status !== 200) throw new Error(`Baidu ${r.status}`);
      return JSON.parse(r.responseText).trans[0].dst;
    }
  };

  // ── Yandex ──
  Engine.yandex = {
    name: 'Yandex',
    needsAuth: true,
    supportsBatch: false,
    _reqId: null,
    _idx: 0,
    langCode(lang) {
      const m = { zh:'zh',en:'en',ja:'ja',ko:'ko',fr:'fr',de:'de',es:'es',ru:'ru',pt:'pt',
        ar:'ar',th:'th',vi:'vi',it:'it',tr:'tr',id:'id' };
      return m[lang] || lang;
    },
    async auth() {
      if (this._reqId) return;
      const r = await gmFetch({ method:'GET', url:'https://translate.yandex.com' });
      if (r.status !== 200) throw new Error(`Yandex auth ${r.status}`);
      const m = /reqid\s*=\s*'([^']+)'/i.exec(r.responseText);
      if (m) this._reqId = m[1]; else throw new Error('Yandex reqid not found');
    },
    async translate(text, toLang) {
      await this.auth();
      const to = this.langCode(toLang);
      const r = await gmFetch({
        method:'POST', anonymous:true,
        url:`https://translate.yandex.net/api/v1/tr.json/translate?id=${this._reqId}-${this._idx++}-0&srv=tr-text&source_lang=auto&target_lang=${to}&reason=type-end&format=text&ajax=1`,
        headers:{ 'content-type':'application/x-www-form-urlencoded','origin':'https://translate.yandex.com','referer':'https://translate.yandex.com/' },
        data:`text=${encodeURIComponent(text)}&options=4`,
      });
      if (r.status !== 200) throw new Error(`Yandex ${r.status}`);
      return JSON.parse(r.responseText).text[0];
    }
  };

  // ── 福昕翻译 ──
  Engine.fuxi = {
    name: 'Fuxi',
    needsAuth: false,
    supportsBatch: false,
    langCode(lang) {
      const m = { zh:'zh-CN',en:'en',ja:'ja',ko:'ko',fr:'fr',de:'de',es:'es',ru:'ru' };
      return m[lang] || lang;
    },
    async translate(text, toLang) {
      const to = this.langCode(toLang);
      const ts = Date.now();
      const sign = md5(ts + 'FOXIT_YEE_TRANSLATE');
      const r = await gmFetch({
        method:'POST', url:'https://fanyi.pdf365.cn/api/wordTranslateResult',
        headers:{ 'content-type':'application/x-www-form-urlencoded; charset=UTF-8','origin':'https://fanyi.pdf365.cn','referer':'https://fanyi.pdf365.cn/free' },
        data:`plateform=web&orginL=auto&targetL=${to}&text=${encodeURIComponent(text)}&timestamp=${ts}&sign=${sign}&userId=`,
      });
      if (r.status !== 200) throw new Error(`Fuxi ${r.status}`);
      return JSON.parse(r.responseText).result;
    }
  };


  // ════════════════════════════
  //  引擎名称列表（UI用）
  // ════════════════════════════
  const ENGINE_LIST = [
    ['microsoft', 'Microsoft'],
    ['google',    'Google'],
    ['tencent',   'Tencent'],
    ['deepl',     'DeepL'],
    ['alibaba',   'Alibaba'],
    ['papago',    'Papago'],
    ['youdao',    'Youdao'],
    ['caiyun',    'Caiyun'],
    ['baidu',     'Baidu'],
    ['yandex',    'Yandex'],
    ['fuxi',      'Fuxi'],
  ];


  // ════════════════════════════
  //  持久化状态
  // ════════════════════════════
  let currentEngine  = await GM_getValue('engine', 'microsoft');
  let targetLang     = await GM_getValue('targetLang', deviceLang);
  let autoMode       = await GM_getValue('autoMode', false);
  let bilingualMode  = await GM_getValue('bilingualMode', false);

  // 验证引擎存在
  if (!Engine[currentEngine]) currentEngine = 'microsoft';


  // ════════════════════════════
  //  LRU 缓存
  // ════════════════════════════
  //
  // 同构性：cache 是原文空间到译文空间的部分函数
  // 性质：|cache| ≤ MAX_CACHE (bounded)
  //
  const cache = new Map();
  function cacheGet(k) { return cache.get(k) || null; }
  function cacheSet(k, v) {
    if (!k || !v || k === v) return;
    if (cache.size >= MAX_CACHE) {
      const first = cache.keys().next().value;
      cache.delete(first);
    }
    cache.set(k, v);
  }
  function cacheClear() { cache.clear(); }


  // ════════════════════════════
  //  语言检测
  // ════════════════════════════

  function detectScript(text) {
    if (!text) return 'empty';
    const t = text.trim().replace(/[\s\d\p{P}\p{S}]/gu, '');
    if (!t) return 'empty';
    const len = t.length;
    const cjk  = (t.match(/[\u4e00-\u9fff\u3400-\u4dbf]/g) || []).length;
    const jp   = (t.match(/[\u3040-\u309f\u30a0-\u30ff]/g) || []).length;
    const kr   = (t.match(/[\uac00-\ud7af]/g) || []).length;
    const ar   = (t.match(/[\u0600-\u06ff]/g) || []).length;
    const thai = (t.match(/[\u0e00-\u0e7f]/g) || []).length;
    const cyrl = (t.match(/[\u0400-\u04ff]/g) || []).length;
    const latin= (t.match(/[a-zA-ZÀ-ÿ]/g) || []).length;

    const ratio = n => n / len;
    if (ratio(cjk) > 0.4) return 'zh';
    if (ratio(jp) > 0.2)  return 'ja';
    if (ratio(kr) > 0.3)  return 'ko';
    if (ratio(ar) > 0.3)  return 'ar';
    if (ratio(thai) > 0.3) return 'th';
    if (ratio(cyrl) > 0.3) return 'ru';
    if (ratio(latin) > 0.4) return 'latin';
    return 'other';
  }

  function isAlreadyTarget(text) {
    const script = detectScript(text);
    if (script === 'empty') return true;

    // 目标语言和检测脚本匹配时视为已翻译
    if (targetLang === 'zh' && script === 'zh') return true;
    if (targetLang === 'ja' && (script === 'ja' || script === 'zh')) return false; // 日语含汉字，不跳过
    if (targetLang === 'ko' && script === 'ko') return true;
    if (targetLang === 'ar' && script === 'ar') return true;
    if (targetLang === 'th' && script === 'th') return true;
    if (targetLang === 'ru' && script === 'ru') return true;

    // 拉丁系语言之间无法用字符区分
    // 只在目标语言是非拉丁系时，跳过拉丁文本
    // 这个策略是保守的：可能误判，但不会漏翻
    return false;
  }


  // ════════════════════════════
  //  DOM节点收集
  // ════════════════════════════

  const SKIP_TAGS = new Set([
    'script','style','code','pre','svg','math','noscript','iframe',
    'canvas','video','audio','img','br','hr','select','option',
    'link','meta','head','template','object','embed',
  ]);

  const SKIP_CLASS_RE = /translate-ui|notranslate|katex|mathjax|highlight|monaco|ace_editor|cm-editor|hljs|prism|code-block|syntaxhighlighter/i;

  function shouldSkipEl(el) {
    if (!el || el.nodeType !== Node.ELEMENT_NODE) return false;
    if (SKIP_TAGS.has(el.tagName.toLowerCase())) return true;
    if (el.isContentEditable) return true;
    if (SKIP_CLASS_RE.test(el.className || '')) return true;
    if (el.closest && el.closest('.translate-ui')) return true;
    // 跳过已翻译
    if (el.dataset && el.dataset.translated) return true;
    return false;
  }

  // 检查祖先链是否有需要跳过的元素 (缓存友好的向上遍历)
  function hasSkippedAncestor(el, root) {
    let node = el;
    while (node && node !== root && node !== document.body) {
      if (shouldSkipEl(node)) return true;
      node = node.parentElement;
    }
    return false;
  }

  function collectTextNodes(root) {
    const nodes = [];
    const walker = document.createTreeWalker(root, NodeFilter.SHOW_TEXT, {
      acceptNode(node) {
        const parent = node.parentElement;
        if (!parent) return NodeFilter.FILTER_REJECT;

        // 快速检查：直接父元素
        if (shouldSkipEl(parent)) return NodeFilter.FILTER_REJECT;

        // 已翻译检查
        if (parent.dataset.translated) return NodeFilter.FILTER_REJECT;
        if (parent.closest('[data-translated]')) return NodeFilter.FILTER_REJECT;

        const text = node.textContent;
        if (!text) return NodeFilter.FILTER_REJECT;
        const trimmed = text.trim();
        if (trimmed.length <= MIN_TEXT_LEN) return NodeFilter.FILTER_REJECT;

        // 纯数字、纯符号
        if (/^[\d\s.,;:!?@#$%^&*()_+\-=\[\]{}'"|\\/<>~`]+$/.test(trimmed)) return NodeFilter.FILTER_REJECT;

        // 单个字母/字符
        if (/^[a-zA-Z]$/.test(trimmed)) return NodeFilter.FILTER_REJECT;

        // 已经是目标语言
        if (isAlreadyTarget(trimmed)) return NodeFilter.FILTER_REJECT;

        // 祖先链检查 (更完整但略慢，放在最后)
        if (hasSkippedAncestor(parent, root)) return NodeFilter.FILTER_REJECT;

        return NodeFilter.FILTER_ACCEPT;
      }
    });
    while (walker.nextNode()) nodes.push(walker.currentNode);
    return nodes;
  }

  function collectPlaceholders(root) {
    const result = [];
    try {
      const els = root.querySelectorAll('input[placeholder], textarea[placeholder]');
      for (const el of els) {
        if (el.dataset.translated) continue;
        const ph = (el.placeholder || '').trim();
        if (ph.length > MIN_TEXT_LEN && !isAlreadyTarget(ph)) {
          result.push(el);
        }
      }
    } catch (_) {}
    return result;
  }

  // title 属性收集
  function collectTitles(root) {
    const result = [];
    try {
      const els = root.querySelectorAll('[title]');
      for (const el of els) {
        if (el.dataset.translatedTitle) continue;
        const t = (el.title || '').trim();
        if (t.length > MIN_TEXT_LEN && !isAlreadyTarget(t)) {
          result.push(el);
        }
      }
    } catch (_) {}
    return result;
  }

  // alt 属性收集
  function collectAlts(root) {
    const result = [];
    try {
      const els = root.querySelectorAll('img[alt]');
      for (const el of els) {
        if (el.dataset.translatedAlt) continue;
        const a = (el.alt || '').trim();
        if (a.length > MIN_TEXT_LEN && !isAlreadyTarget(a)) {
          result.push(el);
        }
      }
    } catch (_) {}
    return result;
  }


  // ════════════════════════════
  //  批量翻译调度器
  // ════════════════════════════
  //
  // 定理 (输出长度守恒):
  //   |batchTranslate(texts)| = |texts|
  //   ∀ i, results[i] ∈ string ∪ {null}
  //

  async function batchTranslate(texts) {
    const n = texts.length;
    if (n === 0) return [];

    const results = new Array(n).fill(null);
    const uncached = [];
    const uncachedIdx = [];

    // 阶段1: 缓存命中
    for (let i = 0; i < n; i++) {
      const t = texts[i].trim();
      if (!t || t.length > MAX_TEXT_LEN) continue;
      if (/^[\d\s.,]+$/.test(t)) continue;
      const c = cacheGet(t);
      if (c !== null) { results[i] = c; continue; }
      uncached.push(t);
      uncachedIdx.push(i);
    }

    if (uncached.length === 0) return results;

    const engine = Engine[currentEngine];
    if (!engine) return results;

    // 鉴权
    if (engine.needsAuth) {
      try { await engine.auth(); } catch (e) { console.warn('auth failed:', e); return results; }
    }

    // 阶段2: 引擎原生批量
    if (engine.supportsBatch && engine.translateBatch) {
      try {
        const batchRes = await engine.translateBatch(uncached, targetLang);
        for (let i = 0; i < batchRes.length; i++) {
          if (batchRes[i] && batchRes[i] !== uncached[i]) {
            cacheSet(uncached[i], batchRes[i]);
            results[uncachedIdx[i]] = batchRes[i];
          }
        }
        return results;
      } catch (e) {
        console.warn('batch failed, fallback:', e);
      }
    }

    // 阶段3: 并发逐条
    for (let i = 0; i < uncached.length; i += CONCURRENCY) {
      const chunk = uncached.slice(i, i + CONCURRENCY);
      const chunkIdx = uncachedIdx.slice(i, i + CONCURRENCY);
      await Promise.allSettled(chunk.map(async (text, j) => {
        try {
          const res = await engine.translate(text, targetLang);
          if (res && res !== text) {
            cacheSet(text, res);
            results[chunkIdx[j]] = res;
          }
        } catch (e) {
          // 静默
        }
      }));
      // 每批次间隔，避免速率限制
      if (i + CONCURRENCY < uncached.length) await sleep(50);
    }

    return results;
  }


  // ════════════════════════════
  //  DOM 替换策略
  // ════════════════════════════

  // ── 纯替换 ──
  // 前置: node 是文本节点，translated 非空
  // 后置: node.textContent = translated, parent.dataset.origText = original
  function applyReplace(textNode, translated) {
    const parent = textNode.parentElement;
    if (!parent || parent.dataset.translated) return;

    const original = textNode.textContent;
    if (!parent.dataset.origText) {
      parent.dataset.origText = original;
    }
    parent.dataset.translated = '1';
    textNode.textContent = translated;
  }

  // ── 双语结构 ──
  // 前置: node 是文本节点，translated 非空
  // 后置: node 被替换为 <span data-translated data-orig-text>
  //         <span class="bt-s">original</span>
  //         <span class="bt-d">translated</span>
  //       </span>
  //
  // 不变量 I₅:
  //   wrapper.querySelector('.bt-s').textContent = original
  //   wrapper.querySelector('.bt-d').textContent = translated
  //   wrapper.dataset.origText = original (用于还原)
  function applyBilingual(textNode, translated) {
    const parent = textNode.parentElement;
    if (!parent) return;

    // 检查是否已在双语wrapper内
    if (parent.dataset.translated || parent.closest('[data-translated]')) return;

    const original = textNode.textContent;

    const wrapper = document.createElement('span');
    wrapper.dataset.translated = '1';
    wrapper.dataset.origText = original;
    wrapper.dataset.biMode = '1';
    wrapper.className = 'bt-wrap';

    const srcSpan = document.createElement('span');
    srcSpan.className = 'bt-s';
    srcSpan.textContent = original;

    const dstSpan = document.createElement('span');
    dstSpan.className = 'bt-d';
    dstSpan.textContent = translated;

    wrapper.appendChild(srcSpan);
    wrapper.appendChild(dstSpan);

    try {
      textNode.parentNode.replaceChild(wrapper, textNode);
    } catch (_) {}
  }

  // 统一替换入口
  function applyTranslation(textNode, translated) {
    if (bilingualMode) {
      applyBilingual(textNode, translated);
    } else {
      applyReplace(textNode, translated);
    }
  }


  // ════════════════════════════
  //  页面翻译
  // ════════════════════════════

  let translating = false;
  let pendingRoots = new Set();

  async function translatePage(root) {
    root = root || document.body;

    if (translating) {
      // 排队
      pendingRoots.add(root);
      return;
    }

    translating = true;

    try {
      await _doTranslate(root);

      // 处理排队的
      while (pendingRoots.size > 0) {
        const roots = [...pendingRoots];
        pendingRoots.clear();
        for (const r of roots) {
          await _doTranslate(r);
        }
      }
    } finally {
      translating = false;
    }
  }

  async function _doTranslate(root) {
    // ── 文本节点 ──
    const textNodes = collectTextNodes(root);
    if (textNodes.length > 0) {
      const texts = textNodes.map(n => n.textContent.trim());
      const results = await batchTranslate(texts);
      for (let i = 0; i < textNodes.length; i++) {
        if (!results[i]) continue;
        const node = textNodes[i];
        if (!node.parentElement) continue;
        if (node.parentElement.dataset.translated) continue;
        applyTranslation(node, results[i]);
      }
    }

    // ── placeholder ──
    const phs = collectPlaceholders(root);
    if (phs.length > 0) {
      const phTexts = phs.map(el => el.placeholder.trim());
      const phResults = await batchTranslate(phTexts);
      for (let i = 0; i < phs.length; i++) {
        if (!phResults[i]) continue;
        phs[i].dataset.origPlaceholder = phs[i].placeholder;
        phs[i].placeholder = phResults[i];
        phs[i].dataset.translated = '1';
      }
    }

    // ── title 属性 ──
    const titles = collectTitles(root);
    if (titles.length > 0) {
      const titleTexts = titles.map(el => el.title.trim());
      const titleResults = await batchTranslate(titleTexts);
      for (let i = 0; i < titles.length; i++) {
        if (!titleResults[i]) continue;
        titles[i].dataset.origTitle = titles[i].title;
        titles[i].title = titleResults[i];
        titles[i].dataset.translatedTitle = '1';
      }
    }

    // ── alt 属性 ──
    const alts = collectAlts(root);
    if (alts.length > 0) {
      const altTexts = alts.map(el => el.alt.trim());
      const altResults = await batchTranslate(altTexts);
      for (let i = 0; i < alts.length; i++) {
        if (!altResults[i]) continue;
        alts[i].dataset.origAlt = alts[i].alt;
        alts[i].alt = altResults[i];
        alts[i].dataset.translatedAlt = '1';
      }
    }

    // ── document.title ──
    if (root === document.body && document.title && !document._titleTranslated) {
      const titleText = document.title.trim();
      if (titleText.length > MIN_TEXT_LEN && !isAlreadyTarget(titleText)) {
        const [result] = await batchTranslate([titleText]);
        if (result) {
          document._origTitle = document.title;
          document.title = result;
          document._titleTranslated = true;
        }
      }
    }
  }


  // ════════════════════════════
  //  还原
  // ════════════════════════════
  //
  // 后置条件: DOM回到翻译前状态
  // 证明: 每种翻译操作都保存了原始值，还原时精确恢复
  //

  function restorePage() {
    // 双语结构还原: wrapper → 文本节点
    document.querySelectorAll('[data-bi-mode]').forEach(el => {
      const orig = el.dataset.origText;
      if (orig !== undefined) {
        const textNode = document.createTextNode(orig);
        try { el.parentNode.replaceChild(textNode, el); } catch (_) {}
      }
    });

    // 纯替换还原
    document.querySelectorAll('[data-translated]:not([data-bi-mode])').forEach(el => {
      // 文本内容还原
      if (el.dataset.origText !== undefined) {
        // 找第一个文本节点替换
        let restored = false;
        for (const child of el.childNodes) {
          if (child.nodeType === Node.TEXT_NODE) {
            child.textContent = el.dataset.origText;
            restored = true;
            break;
          }
        }
        if (!restored) {
          // 没有文本节点就设 textContent (保守策略)
          // 但要注意不破坏子元素
        }
        delete el.dataset.origText;
        delete el.dataset.translated;
      }

      // placeholder 还原
      if (el.dataset.origPlaceholder !== undefined) {
        el.placeholder = el.dataset.origPlaceholder;
        delete el.dataset.origPlaceholder;
        delete el.dataset.translated;
      }
    });

    // title 还原
    document.querySelectorAll('[data-translated-title]').forEach(el => {
      if (el.dataset.origTitle !== undefined) {
        el.title = el.dataset.origTitle;
        delete el.dataset.origTitle;
        delete el.dataset.translatedTitle;
      }
    });

    // alt 还原
    document.querySelectorAll('[data-translated-alt]').forEach(el => {
      if (el.dataset.origAlt !== undefined) {
        el.alt = el.dataset.origAlt;
        delete el.dataset.origAlt;
        delete el.dataset.translatedAlt;
      }
    });

    // document.title 还原
    if (document._titleTranslated && document._origTitle) {
      document.title = document._origTitle;
      delete document._origTitle;
      delete document._titleTranslated;
    }
  }


  // ════════════════════════════
  //  双语切换
  // ════════════════════════════

  async function toggleBilingual() {
    bilingualMode = !bilingualMode;
    GM_setValue('bilingualMode', bilingualMode);

    // 还原后用新模式重翻
    restorePage();
    cacheClear(); // 清缓存保证重新走翻译流程
    updateUI();

    if (autoMode) {
      await sleep(100);
      await translatePage();
    }
  }


  // ════════════════════════════
  //  滚动 & Mutation 监听
  // ════════════════════════════

  let scrollTimer = null;
  let lastDocH = document.documentElement.scrollHeight;

  function onScroll() {
    if (!autoMode) return;
    if (scrollTimer) clearTimeout(scrollTimer);
    scrollTimer = setTimeout(() => {
      const h = document.documentElement.scrollHeight;
      if (h > lastDocH + 80) {
        lastDocH = h;
        translatePage();
      }
    }, SCROLL_DEBOUNCE);
  }

  let mutationTimer = null;
  const observer = new MutationObserver(mutations => {
    if (!autoMode) return;
    if (mutationTimer) clearTimeout(mutationTimer);
    mutationTimer = setTimeout(() => {
      const targets = new Set();
      for (const m of mutations) {
        for (const node of m.addedNodes) {
          if (node.nodeType === Node.ELEMENT_NODE && !shouldSkipEl(node)) {
            targets.add(node);
          }
        }
      }
      if (targets.size === 0) return;
      if (targets.size > 30) {
        translatePage();
      } else {
        targets.forEach(t => translatePage(t));
      }
    }, MUTATION_DEBOUNCE);
  });


  // ════════════════════════════
  //  样式
  // ════════════════════════════

  GM_addStyle(`
    /* 按钮 */
    .translate-ui{position:fixed;bottom:20px;right:20px;z-index:2147483647;
      font-family:system-ui,-apple-system,BlinkMacSystemFont,'Segoe UI',Roboto,sans-serif;
      -webkit-tap-highlight-color:transparent;line-height:1.4}
    .translate-ui *{box-sizing:border-box;margin:0;padding:0}

    .tu-btn{width:44px;height:44px;border-radius:50%;border:none;cursor:pointer;
      display:flex;align-items:center;justify-content:center;
      background:rgba(0,0,0,.45);color:#fff;
      backdrop-filter:blur(10px);-webkit-backdrop-filter:blur(10px);
      box-shadow:0 2px 12px rgba(0,0,0,.18);
      transition:transform .15s,background .2s;
      touch-action:manipulation;-webkit-user-select:none;user-select:none}
    .tu-btn:active{transform:scale(.88)}
    .tu-btn.active{background:rgba(34,128,255,.8)}
    .tu-btn svg{pointer-events:none}

    /* 面板 */
    .tu-panel{position:absolute;bottom:54px;right:0;width:230px;border-radius:14px;padding:14px 16px;
      display:none;
      background:rgba(255,255,255,.97);
      backdrop-filter:blur(16px);-webkit-backdrop-filter:blur(16px);
      box-shadow:0 8px 32px rgba(0,0,0,.14);
      color:#222;font-size:13px}
    .tu-panel.show{display:block;animation:tuIn .15s ease}
    @keyframes tuIn{from{opacity:0;transform:translateY(8px)}to{opacity:1;transform:none}}

    .tu-panel label{display:block;margin:10px 0 4px;font-size:11px;color:#999;
      text-transform:uppercase;letter-spacing:.6px;font-weight:600}
    .tu-panel label:first-child{margin-top:0}

    .tu-panel select{width:100%;padding:7px 10px;border:1px solid #e0e0e0;border-radius:8px;
      font-size:13px;background:#fff;color:#222;outline:none;
      -webkit-appearance:auto;appearance:auto}
    .tu-panel select:focus{border-color:#4a9eff;box-shadow:0 0 0 2px rgba(74,158,255,.15)}

    .tu-acts{display:flex;gap:6px;margin-top:12px;flex-wrap:wrap}
    .tu-acts button{flex:1;min-width:0;padding:8px 4px;border:none;border-radius:8px;
      font-size:12px;font-weight:500;cursor:pointer;
      transition:background .15s,transform .1s;touch-action:manipulation;white-space:nowrap}
    .tu-acts button:active{transform:scale(.95)}

    .tu-go{background:#4a9eff;color:#fff}
    .tu-go:hover{background:#3b8de6}
    .tu-rest{background:#f0f0f0;color:#555}
    .tu-rest:hover{background:#e4e4e4}
    .tu-bi{background:#f5e6ff;color:#7c3aed}
    .tu-bi:hover{background:#ebe0f5}
    .tu-bi.on{background:#7c3aed;color:#fff}

    /* ── 双语结构 ── */
    .bt-wrap{display:inline}
    .bt-s{display:block;opacity:.5;font-size:.88em;line-height:1.35;color:inherit}
    .bt-d{display:block;line-height:1.4;color:inherit}

    /* 行内元素的双语：不换行 */
    a .bt-wrap, span .bt-wrap, em .bt-wrap, strong .bt-wrap, b .bt-wrap, i .bt-wrap,
    label .bt-wrap, td .bt-wrap, th .bt-wrap, li .bt-wrap, button .bt-wrap {
      display:inline
    }
    a .bt-s, span .bt-s, em .bt-s, strong .bt-s, b .bt-s, i .bt-s,
    label .bt-s, td .bt-s, th .bt-s, li .bt-s, button .bt-s {
      display:inline;margin-right:4px
    }
    a .bt-d, span .bt-d, em .bt-d, strong .bt-d, b .bt-d, i .bt-d,
    label .bt-d, td .bt-d, th .bt-d, li .bt-d, button .bt-d {
      display:inline
    }

    /* 段落的双语 */
    p .bt-s, h1 .bt-s, h2 .bt-s, h3 .bt-s, h4 .bt-s, h5 .bt-s, h6 .bt-s,
    div .bt-s, blockquote .bt-s, figcaption .bt-s, dd .bt-s, dt .bt-s {
      display:block;margin-bottom:2px
    }

    /* ── 暗色 ── */
    @media(prefers-color-scheme:dark){
      .tu-panel{background:rgba(28,28,30,.97);color:#f0f0f0}
      .tu-panel select{background:#2c2c2e;color:#f0f0f0;border-color:#444}
      .tu-rest{background:#333;color:#ccc}
      .tu-bi{background:#3b2063;color:#c4a1ff}
      .tu-bi.on{background:#7c3aed;color:#fff}
      .bt-s{opacity:.4}
    }

    /* ── 手机 ── */
    @media(max-width:600px){
      .translate-ui{bottom:12px;right:12px}
      .tu-btn{width:40px;height:40px}
      .tu-panel{width:210px;padding:12px;bottom:50px}
    }
  `);


  // ════════════════════════════
  //  UI 构建
  // ════════════════════════════

  const LANG_OPTIONS = [
    ['zh','中文'],['en','English'],['ja','日本語'],['ko','한국어'],
    ['fr','Français'],['de','Deutsch'],['es','Español'],['ru','Русский'],
    ['pt','Português'],['ar','العربية'],['th','ไทย'],['vi','Tiếng Việt'],
    ['it','Italiano'],['tr','Türkçe'],['id','Indonesia'],['hi','हिन्दी'],
    ['nl','Nederlands'],['pl','Polski'],['uk','Українська'],['cs','Čeština'],
    ['sv','Svenska'],['da','Dansk'],['fi','Suomi'],['el','Ελληνικά'],
    ['ro','Română'],['hu','Magyar'],['ms','Melayu'],['tl','Filipino'],
  ];

  const engineOptionsHTML = ENGINE_LIST.map(([v,t]) => `<option value="${v}">${t}</option>`).join('');
  const langOptionsHTML = LANG_OPTIONS.map(([v,t]) => `<option value="${v}">${t}</option>`).join('');

  const ui = document.createElement('div');
  ui.className = 'translate-ui';
  ui.innerHTML = `
    <div class="tu-panel" id="tuPanel">
      <label>Engine</label>
      <select id="tuEngine">${engineOptionsHTML}</select>
      <label>Language</label>
      <select id="tuLang">${langOptionsHTML}</select>
      <div class="tu-acts">
        <button class="tu-go" id="tuGo">翻译</button>
        <button class="tu-rest" id="tuRest">还原</button>
      </div>
      <div class="tu-acts">
        <button class="tu-bi" id="tuBi">双语</button>
      </div>
    </div>
    <button class="tu-btn" id="tuBtn" aria-label="Translate">
      <svg width="20" height="20" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
        <path d="M3 5h12M9 3v2m1.048 9.5A18.022 18.022 0 016.412 9m6.088 9h7M11 21l5-10 5 10M12.751 5C11.783 10.77 8.07 15.61 3 18.129"/>
      </svg>
    </button>`;
  document.body.appendChild(ui);

  const elBtn    = document.getElementById('tuBtn');
  const elPanel  = document.getElementById('tuPanel');
  const elEngine = document.getElementById('tuEngine');
  const elLang   = document.getElementById('tuLang');
  const elBi     = document.getElementById('tuBi');

  elEngine.value = currentEngine;
  elLang.value   = targetLang;

  function updateUI() {
    elBtn.classList.toggle('active', autoMode);
    elBi.classList.toggle('on', bilingualMode);
    elBi.textContent = bilingualMode ? '双语 ✓' : '双语';
    elEngine.value = currentEngine;
    elLang.value = targetLang;
  }
  updateUI();

  // ── 事件 ──
  elBtn.addEventListener('click', e => {
    e.stopPropagation();
    elPanel.classList.toggle('show');
  });

  const closePanel = e => {
    if (!ui.contains(e.target)) elPanel.classList.remove('show');
  };
  document.addEventListener('click', closePanel);
  document.addEventListener('touchstart', closePanel, { passive: true });

  elEngine.addEventListener('change', async () => {
    currentEngine = elEngine.value;
    GM_setValue('engine', currentEngine);
    cacheClear();

    // 如果当前有翻译，还原后重翻
    if (autoMode) {
      restorePage();
      await sleep(100);
      await translatePage();
    }
  });

  elLang.addEventListener('change', async () => {
    targetLang = elLang.value;
    GM_setValue('targetLang', targetLang);
    cacheClear();

    if (autoMode) {
      restorePage();
      await sleep(100);
      await translatePage();
    }
  });

  document.getElementById('tuGo').addEventListener('click', async () => {
    elPanel.classList.remove('show');
    autoMode = true;
    GM_setValue('autoMode', true);
    restorePage();
    cacheClear();
    lastDocH = document.documentElement.scrollHeight;
    updateUI();
    await translatePage();
  });

  document.getElementById('tuRest').addEventListener('click', () => {
    elPanel.classList.remove('show');
    autoMode = false;
    GM_setValue('autoMode', false);
    restorePage();
    updateUI();
  });

  elBi.addEventListener('click', async () => {
    elPanel.classList.remove('show');
    await toggleBilingual();
  });


  // ── 油猴菜单 ──
  GM_registerMenuCommand('翻译页面', () => {
    autoMode = true; GM_setValue('autoMode', true); updateUI(); translatePage();
  });
  GM_registerMenuCommand('还原页面', () => {
    autoMode = false; GM_setValue('autoMode', false); updateUI(); restorePage();
  });
  GM_registerMenuCommand('切换双语', () => toggleBilingual());
  GM_registerMenuCommand('切换引擎', () => {
    const keys = ENGINE_LIST.map(e => e[0]);
    const idx = keys.indexOf(currentEngine);
    currentEngine = keys[(idx + 1) % keys.length];
    GM_setValue('engine', currentEngine);
    cacheClear();
    updateUI();
    if (autoMode) { restorePage(); translatePage(); }
  });


  // ════════════════════════════
  //  页面语言检测 & 启动
  // ════════════════════════════

  function isPageTargetLang() {
    const htmlLang = (document.documentElement.lang || '').toLowerCase().split('-')[0];
    if (htmlLang && htmlLang === targetLang) return true;

    // 无lang属性时抽样
    if (!htmlLang) {
      const body = document.body;
      if (!body) return false;
      const sample = (body.innerText || '').substring(0, 600);
      if (sample.length < 20) return false;
      return isAlreadyTarget(sample);
    }
    return false;
  }

  // 启动观察者
  window.addEventListener('scroll', onScroll, { passive: true });
  observer.observe(document.body, { childList: true, subtree: true });

  // 自动翻译
  if (autoMode && !isPageTargetLang()) {
    setTimeout(() => translatePage(), STARTUP_DELAY);
  }

})();