// ==UserScript==
// @name         VKvideo 实时双语字幕
// @version      1.1.1
// @description  俄网VK Video实时中俄双语字幕 — Yandex优先，支持上下文翻译
// @author       zzzdawei
// @match        *://vk.com/*
// @match        *://*.vk.com/*
// @match        *://vk.ru/*
// @match        *://*.vk.ru/*
// @match        *://vkvideo.ru/*
// @match        *://*.vkvideo.ru/*
// @grant        GM.xmlHttpRequest
// @grant        GM_addStyle
// @grant        unsafeWindow
// @connect      *
// @connect      okcdn.ru
// @connect      vkuser.net
// @connect      vk-cdn.net
// @connect      vot.toil.cc
// @run-at       document-start
// ==/UserScript==

(function () {
  "use strict";

  // ═══════════════════════════════════════════════════════════════════════
  // 1. CONFIG
  // ═══════════════════════════════════════════════════════════════════════
  var TRANSLATE_TO = "zh";
  var TRANSLATE_ENABLED = true;

  // ═══════════════════════════════════════════════════════════════════════
  // 2. UTILS
  // ═══════════════════════════════════════════════════════════════════════
  var log   = function () { console.log  .apply(console, ["[VK Subs]"].concat(Array.prototype.slice.call(arguments))); };
  var warn  = function () { console.warn .apply(console, ["[VK Subs]"].concat(Array.prototype.slice.call(arguments))); };

  /** MM:SS panel display */
  function formatTime(sec) {
    var m = Math.floor(sec / 60), s = Math.floor(sec % 60);
    return (m < 10 ? "0" : "") + m + ":" + (s < 10 ? "0" : "") + s;
  }

  /** VTT timestamp: HH:MM:SS.mmm or MM:SS.mmm */
  function formatVttTime(sec) {
    var h = Math.floor(sec / 3600), m = Math.floor((sec % 3600) / 60), s = Math.floor(sec % 60), ms = Math.floor((sec % 1) * 1000);
    var ts = (m < 10 ? "0" : "") + m + ":" + (s < 10 ? "0" : "") + s + "." + (ms < 100 ? (ms < 10 ? "00" : "0") : "") + ms;
    return h > 0 ? ((h < 10 ? "0" : "") + h + ":" + ts) : ts;
  }

  /** SRT timestamp: HH:MM:SS,mmm */
  function formatSrtTime(sec) {
    var h = Math.floor(sec / 3600), m = Math.floor((sec % 3600) / 60), s = Math.floor(sec % 60), ms = Math.floor((sec % 1) * 1000);
    return (h < 10 ? "0" : "") + h + ":" + (m < 10 ? "0" : "") + m + ":" + (s < 10 ? "0" : "") + s + "," + (ms < 100 ? (ms < 10 ? "00" : "0") : "") + ms;
  }

  function getPageWindow() {
    return typeof unsafeWindow !== "undefined" ? unsafeWindow : globalThis;
  }

  // ═══════════════════════════════════════════════════════════════════════
  // 3. ENCODING — multi-charset VTT decoder
  // ═══════════════════════════════════════════════════════════════════════
  var ENCODINGS = ["utf-8", "windows-1251", "koi8-r", "iso-8859-5"];
  var VTT_HEADER_RE = /^WEBVTT/mu;

  function decodeBuffer(buffer, encoding) {
    try { return new TextDecoder(encoding, { fatal: false }).decode(buffer); } catch (_) { return null; }
  }

  function isLikelyMojibake(text) {
    var c = 0;
    for (var i = 0; i < text.length; i++) { if (text.charCodeAt(i) === 0xfffd) c++; }
    return c > text.length * 0.03;
  }

  function looksLikeVttContent(text) {
    return VTT_HEADER_RE.test(text) || text.indexOf("-->") !== -1;
  }

  /** Decode ArrayBuffer → VTT string, trying all known encodings. */
  function decodeTextFromBuffer(buffer) {
    var best = "";
    for (var e = 0; e < ENCODINGS.length; e++) {
      var decoded = decodeBuffer(buffer, ENCODINGS[e]);
      if (!decoded) continue;
      if (looksLikeVttContent(decoded) && !isLikelyMojibake(decoded)) {
        log("VTT encoding:", ENCODINGS[e], "(" + decoded.length + " chars)");
        return decoded;
      }
      if (!best && looksLikeVttContent(decoded)) best = decoded;
    }
    if (best) { warn("all encodings produced mojibake; using fallback"); return best; }
    return decodeBuffer(buffer, ENCODINGS[0]) || "";
  }

  // ═══════════════════════════════════════════════════════════════════════
  // 4. VTT PARSER
  // ═══════════════════════════════════════════════════════════════════════
  var VTT_TIMING_RE = /^(?<start>(?:\d{2}:)?\d{2}:\d{2}\.\d{3})\s+-->\s+(?<end>(?:\d{2}:)?\d{2}:\d{2}\.\d{3})/u;

  function parseClockTime(v) {
    var p = v.trim().split(":");
    if (p.length === 3) return (parseInt(p[0],10)*3600 + parseInt(p[1],10)*60 + parseFloat(p[2])) * 1000;
    if (p.length === 2) return (parseInt(p[0],10)*60 + parseFloat(p[1])) * 1000;
    return NaN;
  }

  /** Parse WEBVTT text → [{start, end, text}, ...] sorted by start. */
  function parseVtt(text) {
    var normalized = text.replace(/\r/g, "").replace(/^/, "");
    var lines = normalized.split("\n");
    if (!lines[0] || !lines[0].startsWith("WEBVTT")) return [];

    var cues = [], i = 1;
    while (i < lines.length) {
      while (i < lines.length && lines[i].trim() === "") i++;
      if (i >= lines.length) break;
      if (/^(NOTE|STYLE|REGION)\b/i.test(lines[i])) { i++; while (i < lines.length && lines[i].trim() !== "") i++; continue; }
      if (!VTT_TIMING_RE.test(lines[i])) { i++; continue; }

      var m = VTT_TIMING_RE.exec(lines[i]);
      if (!m) { i++; continue; }
      var startMs = parseClockTime(m.groups.start), endMs = parseClockTime(m.groups.end);
      i++;

      var textLines = [];
      while (i < lines.length && lines[i].trim() !== "") {
        var line = lines[i].replace(/<[^>]+>/g, "").replace(/&nbsp;/gi, " ").replace(/&amp;/gi, "&").replace(/&lt;/gi, "<").replace(/&gt;/gi, ">").replace(/&quot;/gi, '"').replace(/&#39;/g, "'");
        textLines.push(line);
        i++;
      }
      var cueText = textLines.join("\n").trim();
      if (!isNaN(startMs) && !isNaN(endMs) && cueText) cues.push({ start: startMs / 1000, end: endMs / 1000, text: cueText });
    }
    cues.sort(function (a, b) { return a.start - b.start; });
    return cues;
  }

  /**
   * Clean VK's auto-generated VTT cues: 5-pass dedup + merge.
   *
   * VK auto-VTT has interleaved formats:
   *   A — short→long corrections at same timestamp
   *   B — daisy-chain pairs: two texts share start time, second repeats as next pair's first
   *
   * P1: group by start time (0.05s tolerance)
   * P2: within-group: drop exact dupes, drop short texts contained in longer siblings
   * P3: cross-group text dedup (daisy-chain repeats within 5s)
   * P4: rolling-window containment merge
   * P5: daisy-chain dedup across \n line boundaries
   */
  function cleanCues(cues) {
    if (!cues.length) return [];

    // P1: group by start time
    cues.sort(function (a, b) { return a.start - b.start; });
    var groups = [], curGroup = [cues[0]];
    for (var i = 1; i < cues.length; i++) {
      if (Math.abs(cues[i].start - curGroup[0].start) < 0.05) curGroup.push(cues[i]);
      else { groups.push(curGroup); curGroup = [cues[i]]; }
    }
    groups.push(curGroup);

    // P2: within-group resolution
    var resolved = [];
    for (var g = 0; g < groups.length; g++) {
      var group = groups[g];
      var unique = [], seen = {};
      for (var j = 0; j < group.length; j++) {
        if (!seen[group[j].text]) { seen[group[j].text] = true; unique.push(group[j]); }
      }
      for (var k = 0; k < unique.length; k++) {
        var contained = false;
        for (var m = 0; m < unique.length; m++) {
          if (k === m) continue;
          if (unique[m].text.length > unique[k].text.length && unique[m].text.indexOf(unique[k].text) !== -1) { contained = true; break; }
        }
        if (!contained) resolved.push(unique[k]);
      }
    }
    if (resolved.length <= 1) return resolved;

    // P3: cross-group text dedup
    var result3 = [], seen3 = {};
    for (var r = 0; r < resolved.length; r++) {
      var cue = resolved[r], prev = seen3[cue.text];
      if (prev !== undefined) {
        if (cue.start - prev.start < 5) { prev.end = Math.max(prev.end, cue.end); continue; }
      }
      seen3[cue.text] = cue;
      result3.push(cue);
    }
    if (result3.length <= 1) return result3;

    // P4: rolling-window containment merge
    var final4 = [result3[0]];
    for (var f = 1; f < result3.length; f++) {
      var p4 = final4[final4.length - 1], c4 = result3[f];
      if (c4.start - p4.start < 5) {
        if (p4.text.length > 3 && c4.text.indexOf(p4.text) !== -1 && c4.text.length > p4.text.length) { final4[final4.length - 1] = { start: p4.start, end: c4.end, text: c4.text }; continue; }
        if (c4.text.length > 3 && p4.text.indexOf(c4.text) !== -1 && p4.text.length > c4.text.length) { p4.end = Math.max(p4.end, c4.end); continue; }
      }
      final4.push(c4);
    }
    if (final4.length <= 1) return final4;

    // P5: daisy-chain across \n boundaries
    var final5 = [final4[0]];
    for (var p = 1; p < final4.length; p++) {
      var p5 = final5[final5.length - 1], c5 = final4[p];
      var pLines = p5.text.split("\n"), cLines = c5.text.split("\n");
      var pLast = pLines[pLines.length - 1].trim(), cFirst = cLines[0].trim();
      if (pLast.length > 3 && pLast === cFirst) {
        if (cLines.length === 1) { p5.end = Math.max(p5.end, c5.end); continue; }
        var stripped = cLines.slice(1).join("\n").trim();
        if (stripped) final5.push({ start: c5.start, end: c5.end, text: stripped });
        else p5.end = Math.max(p5.end, c5.end);
        continue;
      }
      final5.push(c5);
    }
    return final5;
  }

  /** Binary-search the current cue. Prefers longest text among same-timestamp neighbors. */
  function findCurrentCue(cues, time) {
    if (!cues || !cues.length) return null;
    var lo = 0, hi = cues.length - 1, best = null;
    while (lo <= hi) {
      var mid = (lo + hi) >>> 1, cue = cues[mid];
      if (time >= cue.start && time < cue.end) {
        best = cue;
        for (var L = mid - 1; L >= 0 && Math.abs(cues[L].start - cue.start) < 0.05; L--) {
          if (time >= cues[L].start && time < cues[L].end && cues[L].text.length > best.text.length) best = cues[L];
        }
        for (var R = mid + 1; R < cues.length && Math.abs(cues[R].start - cue.start) < 0.05; R++) {
          if (time >= cues[R].start && time < cues[R].end && cues[R].text.length > best.text.length) best = cues[R];
        }
        return best;
      }
      if (time < cue.start) hi = mid - 1; else lo = mid + 1;
    }
    return null;
  }

  // ═══════════════════════════════════════════════════════════════════════
  // 4.5. SENTENCE MERGE — build translation units from VK's tiny fragments
  // ═══════════════════════════════════════════════════════════════════════
  //
  // WHY: VK auto-VTT breaks text every ~2s with no punctuation. Translating
  // individual fragments produces gibberish.  We merge consecutive cues into
  // sentence-level "translation units" capped at 6s / 150 chars so the API
  // gets coherent input.  Display cues stay individual for precise timing.
  var _transUnits = [];

  function mergeToTranslationUnits(cues) {
    if (!cues.length) return [];
    var MAX_DUR = 6;     // hard cap: never merge beyond 6 seconds
    var MAX_CHARS = 150;  // hard cap: never merge beyond 150 characters
    var GAP_S = 0.3;      // gap threshold to force split (natural pause)

    var units = [];
    var cur = { start: cues[0].start, end: cues[0].end, text: cues[0].text };
    for (var i = 1; i < cues.length; i++) {
      var c = cues[i];
      var dur = c.end - cur.start;
      var totalChars = cur.text.length + c.text.length + 1;
      var gap = c.start - cur.end;
      var isEnd = /[.!?]$/.test(cur.text);
      var tooLong = dur > MAX_DUR || totalChars > MAX_CHARS;
      var hasPause = gap > GAP_S;

      if (isEnd || tooLong || hasPause) {
        units.push(cur);
        cur = { start: c.start, end: c.end, text: c.text };
      } else {
        cur.end = c.end;
        cur.text += " " + c.text;
      }
    }
    units.push(cur);
    log("Translation units:", cues.length, "display cues →", units.length, "units");
    return units;
  }

  /**
   * After a translation unit is translated, copy its translation to all
   * display cues whose time range falls within the unit.
   */
  function syncUnitToDisplay(unitText, translation, displayCues) {
    var unit = null;
    for (var u = 0; u < _transUnits.length; u++) {
      if (_transUnits[u].text === unitText) { unit = _transUnits[u]; break; }
    }
    if (!unit) { cacheSet(unitText, translation); return; }
    cacheSet(unitText, translation);
    for (var i = 0; i < displayCues.length; i++) {
      var dc = displayCues[i];
      if (dc.start >= unit.start - 0.05 && dc.end <= unit.end + 0.05) {
        cacheSet(dc.text, translation);
      }
    }
  }

  /** Sync ALL translated units to display cues. */
  function syncAllUnitsToDisplay() {
    var dc = _dedupedCues;
    if (!dc.length || !_transUnits.length) return;
    for (var u = 0; u < _transUnits.length; u++) {
      var unit = _transUnits[u];
      var trans = cacheGet(unit.text);
      if (!trans) continue;
      for (var i = 0; i < dc.length; i++) {
        if (dc[i].start >= unit.start - 0.05 && dc[i].end <= unit.end + 0.05) {
          cacheSet(dc[i].text, trans);
        }
      }
    }
  }

  // ═══════════════════════════════════════════════════════════════════════
  // 5. TRANSLATION ENGINE (fully decoupled)
  // ═══════════════════════════════════════════════════════════════════════
  //
  // Layers:  Cache  →  Context  →  Provider  →  Queue  →  Orchestrator
  //
  //   Cache:       get/set/evict translation entries
  //   Context:     wrap sentence with prev/next for coherent translation
  //   Provider:    call a translation API (Google, VOT/Yandex, etc.)
  //   Queue:       batch + priority-sort + rate-limit the translation work
  //   Orchestrator: wire cache + context + provider + queue together

  // ── 5a. Cache ────────────────────────────────────────────────────────
  var _cache = Object.create(null);
  var _cacheSize = 0;
  var _cacheMax = 3000;

  function cacheGet(key)    { return _cache[key]; }
  function cacheSet(k, v)   { if (!_cache[k]) _cacheSize++; _cache[k] = v; }
  function cacheHas(key)    { return _cache[key] !== undefined; }

  function cacheEvict(n) {
    n = n || 100;
    var keys = Object.keys(_cache);
    for (var i = 0; i < Math.min(n, keys.length); i++) { delete _cache[keys[i]]; _cacheSize--; }
  }

  // ── 5b. Context strategy ─────────────────────────────────────────────
  //
  // WHY: isolated sentences lose pronoun references and discourse flow.
  // Wrapping with neighbors gives the API enough context.
  var CTX_SEP = "◈CTX◈";  // ◈CTX◈ — won't appear in natural text

  /** Wrap cue at index i with prev/next neighbors. */
  function contextWrap(cues, i) {
    var parts = [];
    if (i > 0) parts.push(cues[i - 1].text);
    parts.push(cues[i].text);
    if (i < cues.length - 1) parts.push(cues[i + 1].text);
    return parts.join("\n" + CTX_SEP + "\n");
  }

  /** Extract the target (middle) segment from a context-aware translation result. */
  function contextExtract(translated) {
    var parts = translated.split(CTX_SEP);
    var idx = Math.min(1, Math.floor((parts.length - 1) / 2));
    return (parts[idx] || parts[0] || "").trim();
  }

  // ── 5c. Provider: Google Translate ───────────────────────────────────
  function providerGoogle(text, targetLang) {
    return new Promise(function (resolve, reject) {
      var url = "https://translate.googleapis.com/translate_a/single" +
        "?client=gtx&sl=ru&tl=" + encodeURIComponent(targetLang) +
        "&dt=t&q=" + encodeURIComponent(text);
      GM.xmlHttpRequest({
        method: "GET", url: url, timeout: 5000,
        onload: function (r) {
          try {
            var data = JSON.parse(r.responseText);
            var out = (data[0] || []).map(function (s) { return (s || [])[0] || ""; }).join("");
            out ? resolve(out) : reject(new Error("Empty"));
          } catch (e) { reject(e); }
        },
        onerror: function () { reject(new Error("API error")); },
        ontimeout: function () { reject(new Error("Timeout")); }
      });
    });
  }

  // ── 5c. Provider: VOT Backend (Yandex) ───────────────────────────────
  //
  // WHY: VOT backend proxies to Yandex Translate, producing much better
  // Russian→Chinese than Google's free endpoint.  We fetch BOTH original
  // and translated subtitle tracks — Yandex preserves cue timing so they
  // are 1:1 aligned.
  var VOT_BACKEND = "https://vot.toil.cc/v1";
  var _votOriginal = null;    // VOT original-track cues
  var _votTranslated = null;  // VOT translated-track cues (1:1 aligned)
  var _votApplied = false;

  function extractVkVideoId() {
    if (_loadedVideoId && _loadedVideoId !== "unknown") return _loadedVideoId;
    var m = location.href.match(/video(-?\d+_\d+)/);  if (m) return m[1];
    m = location.href.match(/video(\d{6,})/);          if (m) return m[1];
    if (videoElement && videoElement.src) { m = videoElement.src.match(/(\d{6,})/); if (m) return m[1]; }
    return "unknown";
  }

  /** Fetch and parse a single Yandex JSON subtitle file → cue array. */
  function fetchYandexJson(url) {
    return new Promise(function (resolve) {
      GM.xmlHttpRequest({
        method: "GET", url: url, timeout: 10000,
        onload: function (r) {
          try {
            var data = JSON.parse(r.responseText);
            var items = Array.isArray(data) ? data : (data.subtitles || data.events || []);
            if (!items.length) { resolve(null); return; }
            var cues = [];
            for (var i = 0; i < items.length; i++) {
              var it = items[i];
              var text = it.text || it.caption || "";
              var startMs = it.startMs || it.start || it.tStartMs || 0;
              var dur = it.durationMs || it.duration || (it.endMs ? it.endMs - startMs : 2000);
              if (!text.trim()) continue;
              cues.push({ start: startMs / 1000, end: (startMs + dur) / 1000, text: text.trim() });
            }
            resolve(cues.length > 0 ? cues : null);
          } catch (_) { resolve(null); }
        },
        onerror: function () { resolve(null); },
        ontimeout: function () { resolve(null); }
      });
    });
  }

  /** Fetch BOTH original + translated VOT tracks. Returns {original:[], translated:[]} or null. */
  function providerVotFetchTracks(videoId, targetLang) {
    return new Promise(function (resolve) {
      GM.xmlHttpRequest({
        method: "POST", url: VOT_BACKEND + "/video-subtitles/get-subtitles",
        headers: { "Content-Type": "application/json", "User-Agent": "vot.js/2.4.17" },
        data: JSON.stringify({ service: "vk", video_id: String(videoId), provider: "yandex" }),
        timeout: 10000,
        onload: function (r) {
          try {
            var data = JSON.parse(r.responseText);
            if (!Array.isArray(data) || !data.length) { resolve(null); return; }
            var orig = null, trans = null;
            for (var i = 0; i < data.length; i++) {
              if (!data[i].lang_from) orig = data[i];
              if (data[i].lang === targetLang && data[i].lang_from) trans = data[i];
            }
            if (!orig || !trans || !orig.subtitle_url || !trans.subtitle_url) { resolve(null); return; }
            log("VOT: dual tracks —", orig.lang, "→", trans.lang);
            Promise.all([fetchYandexJson(orig.subtitle_url), fetchYandexJson(trans.subtitle_url)]).then(function (r2) {
              var o = r2[0], t = r2[1];
              if (!o || !t) { resolve(null); return; }
              var len = Math.min(o.length, t.length);
              resolve({ original: o.slice(0, len), translated: t.slice(0, len) });
            });
          } catch (_) { resolve(null); }
        },
        onerror: function () { resolve(null); },
        ontimeout: function () { resolve(null); }
      });
    });
  }

  // ── 5d. Queue: batching + priority + rate limiting ──────────────────
  var _queue = [];
  var _queueTimer = null;
  var _queueTotal = 0;
  var _queueDone = 0;
  var BATCH_SIZE = 8;
  var BATCH_DELAY = 300;   // ms between batches
  var BATCH_RETRY_DELAY = 1500;

  /**
   * Build a priority queue of translation batches.
   * Each uncached cue is wrapped with context.  Batches nearest the
   * current playback position are processed first.
   */
  function queueBuild(cues, curTime) {
    if (!cues || !cues.length) return;
    var batches = [];
    for (var i = 0; i < cues.length; i += BATCH_SIZE) {
      var end = Math.min(i + BATCH_SIZE, cues.length);
      var contexts = [], targets = [], allCached = true;
      for (var j = i; j < end; j++) {
        targets.push(cues[j].text);
        if (!cacheHas(cues[j].text)) { allCached = false; contexts.push(contextWrap(cues, j)); }
        else contexts.push(null);
      }
      if (!allCached) batches.push({ contexts: contexts, targets: targets, firstIdx: i });
    }

    if (!batches.length) { _queueTotal = 0; _queueDone = 0; return; }

    var curIdx = 0;
    for (var k = 0; k < cues.length; k++) { if (curTime >= cues[k].start && curTime < cues[k].end) { curIdx = k; break; } }
    batches.sort(function (a, b) { return Math.abs(a.firstIdx - curIdx) - Math.abs(b.firstIdx - curIdx); });

    _queue = batches;
    _queueTotal = batches.length;
    _queueDone = 0;
  }

  /**
   * Translate a batch of context-wrapped sentences via Google.
   * Splits results back by batch separator, extracts target segment from
   * each context block, and caches the individual translations.
   */
  function queuePumpOne(batch, onDone) {
    var BSEP = "\n\n---VOTSEP---\n\n";
    var uncached = [], targets = [];
    for (var i = 0; i < batch.contexts.length; i++) {
      if (batch.contexts[i] !== null) { uncached.push(batch.contexts[i]); targets.push(batch.targets[i]); }
    }
    if (!uncached.length) { onDone(true); return; }

    providerGoogle(uncached.join(BSEP), TRANSLATE_TO).then(function (result) {
      var blocks = result.split(BSEP);
      for (var i = 0; i < Math.min(uncached.length, blocks.length); i++) {
        var extracted = contextExtract(blocks[i]);
        if (extracted) cacheSet(targets[i], extracted);
      }
      if (blocks.length !== uncached.length) {
        warn("batch split mismatch:", blocks.length, "vs", uncached.length);
        for (var j = 0; j < targets.length; j++) {
          if (!cacheHas(targets[j])) {
            (function (t) { providerGoogle(t, TRANSLATE_TO).then(function (r) { cacheSet(t, r); }); })(targets[j]);
          }
        }
      }
      if (_cacheSize > _cacheMax) cacheEvict(100);
      onDone(true);
    }).catch(function (err) {
      warn("batch error:", err && err.message);
      _queue.unshift(batch);
      onDone(false);
    });
  }

  /** Pump queue at controlled intervals. */
  function queuePump() {
    if (_queue.length === 0) { _queueTimer = null; return; }
    var batch = _queue.shift();
    queuePumpOne(batch, function (ok) {
      _queueDone++;
      syncAllUnitsToDisplay();
      updatePanelTitle();
      refreshPanelTranslations();
      _queueTimer = setTimeout(queuePump, ok ? BATCH_DELAY : BATCH_RETRY_DELAY);
    });
  }

  // ── 5e. Orchestrator — wires cache + context + provider + queue ─────
  var _running = false;
  var _livePending = null;

  /** Start/restart background translation for a cue list. */
  function translationStart(cues, curTime) {
    if (!TRANSLATE_ENABLED) return;
    queueBuild(cues || _transUnits, curTime || 0);
    if (_running) return;
    _running = true;
    queuePump();
  }

  /** Stop background translation. */
  function translationStop() {
    _running = false;
    _queue = [];
    if (_queueTimer) { clearTimeout(_queueTimer); _queueTimer = null; }
    _queueTotal = 0;
    _queueDone = 0;
  }

  /**
   * Live-translate on cache miss during playback.
   * Finds the translation unit containing this display cue, translates the
   * WHOLE unit for coherence, then syncs the result to all display cues
   * within that unit so subsequent fragments are instant.
   */
  function translationLive(text, displayCues) {
    if (!TRANSLATE_ENABLED || !text || _livePending === text) return;
    if (cacheHas(text)) return;
    _livePending = text;

    // Find which translation unit covers this display cue
    var unit = null;
    if (_transUnits.length && displayCues) {
      // Locate the display cue first
      var dcStart = 0;
      for (var d = 0; d < displayCues.length; d++) {
        if (displayCues[d].text === text) { dcStart = displayCues[d].start; break; }
      }
      // Find containing translation unit
      for (var u = 0; u < _transUnits.length; u++) {
        if (dcStart >= _transUnits[u].start - 0.05 && dcStart <= _transUnits[u].end + 0.05) {
          unit = _transUnits[u]; break;
        }
      }
    }

    var payload = unit ? contextWrap(_transUnits, _transUnits.indexOf(unit)) : text;

    providerGoogle(payload, TRANSLATE_TO).then(function (result) {
      var extracted = unit ? contextExtract(result) : result;
      if (unit) {
        cacheSet(unit.text, extracted);
        // Sync to all display cues in this unit
        for (var i = 0; i < displayCues.length; i++) {
          if (displayCues[i].start >= unit.start - 0.05 && displayCues[i].end <= unit.end + 0.05) {
            cacheSet(displayCues[i].text, extracted);
          }
        }
      } else {
        cacheSet(text, extracted);
      }
      refreshPanelTranslations();
      if (overlay && overlay.firstChild && overlay.firstChild.textContent === text) showTranslation(extracted);
      _livePending = null;
    }).catch(function () { _livePending = null; });
  }

  /** Progress string for panel header. */
  function translationProgress() {
    if (_queueTotal === 0) return "Subtitles";
    if (_queueDone >= _queueTotal) return "Subtitles ✓";
    return "Subtitles (" + _queueDone + "/" + _queueTotal + ")";
  }

  /** Update panel header title element. */
  function updatePanelTitle() {
    var el = document.querySelector("#vot-vk-sub-panel [data-trans-title]");
    if (el) el.textContent = translationProgress();
  }

  // ── 5f. VOT backend trigger (fire-and-forget) ────────────────────────
  //
  // Tries VOT backend.  On success, replaces VK cues with VOT's original
  // cues (better text quality) and fills the cache with 1:1 aligned Yandex
  // translations.  Cancels the Google queue since everything is covered.
  function tryVotBackend(videoId) {
    if (!TRANSLATE_ENABLED || _votApplied) return;
    if (!videoId || videoId === "unknown") return;
    _votApplied = true;
    log("VOT: requesting dual-track for", videoId, "→", TRANSLATE_TO);
    providerVotFetchTracks(videoId, TRANSLATE_TO).then(function (tracks) {
      if (!tracks) { log("VOT: nothing available, Google fallback active"); return; }
      _votOriginal = tracks.original;
      _votTranslated = tracks.translated;
      log("VOT: received", tracks.original.length, "cues (1:1 aligned)");

      _dedupedCues = tracks.original;
      _transUnits = tracks.original;  // VOT cues are already sentence-level
      for (var i = 0; i < tracks.original.length; i++) cacheSet(tracks.original[i].text, tracks.translated[i].text);

      translationStop();
      updatePanelTitle();
      rebuildPanel();
      if (overlay && overlay.firstChild && overlay.firstChild.textContent) {
        var c = cacheGet(overlay.firstChild.textContent);
        if (c) showTranslation(c);
      }
    });
  }

  // ═══════════════════════════════════════════════════════════════════════
  // 6. SUBTITLE DOWNLOAD — VTT / SRT bilingual serializers
  // ═══════════════════════════════════════════════════════════════════════

  /** Serialize cue pairs to bilingual VTT. */
  function serializeBilingual(orig, trans, fmt) {
    var fmtTime = fmt === "srt" ? formatSrtTime : formatVttTime;
    var lines = fmt === "srt" ? [] : ["WEBVTT", ""];
    for (var i = 0; i < orig.length; i++) {
      var c = orig[i];
      if (fmt === "srt") lines.push(String(i + 1));
      lines.push(fmtTime(c.start) + " --> " + fmtTime(c.end));
      lines.push(c.text);
      var t = trans ? (trans[i] ? trans[i].text : "") : (cacheGet(c.text) || "");
      if (t) lines.push(t);
      lines.push("");
    }
    return lines.join("\n");
  }

  function triggerDownload(data, filename, mime) {
    try {
      var blob = new Blob([data], { type: mime + ";charset=utf-8" });
      var url = URL.createObjectURL(blob);
      var a = document.createElement("a");
      a.href = url; a.download = filename; a.style.display = "none";
      document.body.appendChild(a); a.click();
      setTimeout(function () { document.body.removeChild(a); URL.revokeObjectURL(url); }, 100);
      log("Download:", filename);
    } catch (e) { warn("Download failed:", e); }
  }

  function downloadBilingualVtt() {
    var orig = _votOriginal || _dedupedCues || activeCues;
    if (!orig.length) { warn("No subtitles"); return; }
    triggerDownload(serializeBilingual(orig, _votTranslated, "vtt"), "vk-subs-" + (_loadedVideoId || "video") + "-bilingual.vtt", "text/vtt");
  }

  function downloadBilingualSrt() {
    var orig = _votOriginal || _dedupedCues || activeCues;
    if (!orig.length) { warn("No subtitles"); return; }
    triggerDownload(serializeBilingual(orig, _votTranslated, "srt"), "vk-subs-" + (_loadedVideoId || "video") + "-bilingual.srt", "text/srt");
  }

  /** Internal: mono VTT (no translation), used for textTracks fallback. */
  function serializeMonoVtt(cues) {
    var lines = ["WEBVTT", ""];
    for (var i = 0; i < cues.length; i++) { lines.push(formatVttTime(cues[i].start) + " --> " + formatVttTime(cues[i].end)); lines.push(cues[i].text); lines.push(""); }
    return lines.join("\n");
  }

  // ═══════════════════════════════════════════════════════════════════════
  // 7. OVERLAY UI — floating subtitle box on video (Shadow DOM)
  // ═══════════════════════════════════════════════════════════════════════
  var OVERLAY_ID = "vot-vk-sub-overlay";
  var overlay = null;
  var overlayMount = null;
  var _dragY = null;
  var _userBottom = 64;

  function resolveOverlayMount() {
    var p = document.querySelector("vk-video-player");
    if (p && p.shadowRoot) return p.shadowRoot;
    var all = document.querySelectorAll("*");
    for (var i = 0; i < all.length; i++) { var sr = all[i].shadowRoot; if (sr && sr.querySelector("video")) return sr; }
    return document.body;
  }

  function getContainerHeight(el) {
    var p = el.parentNode;
    if (!p) return 720;
    if (p.host && p.host.getBoundingClientRect) return p.host.getBoundingClientRect().height || 720;
    if (p.getBoundingClientRect instanceof Function) return p.getBoundingClientRect().height || 720;
    return 720;
  }

  function createOverlay(mount) {
    var el = document.createElement("div");
    el.id = OVERLAY_ID;
    el.style.cssText = "position:absolute;bottom:" + _userBottom + "px;left:50%;transform:translateX(-50%);z-index:999999;max-width:88%;display:none;padding:8px 16px;background:rgba(0,0,0,0.75);color:#fff;font-size:18px;line-height:1.3;text-align:center;border-radius:8px;backdrop-filter:blur(8px);font-family:Arial,Helvetica,sans-serif;box-shadow:0 2px 16px rgba(0,0,0,0.4);";

    var textSpan = document.createElement("span");
    textSpan.style.cssText = "display:block;white-space:nowrap;overflow:hidden;text-overflow:ellipsis;cursor:text;user-select:text;font-size:18px;line-height:1.3;";
    el.appendChild(textSpan);

    var transSpan = document.createElement("span");
    transSpan.className = "vot-trans";
    transSpan.style.cssText = "display:block;white-space:nowrap;overflow:hidden;text-overflow:ellipsis;color:#aaa;font-size:13px;font-style:italic;line-height:1.2;margin-top:2px;";
    el.appendChild(transSpan);

    // Drag handle (top edge)
    var handle = document.createElement("div");
    handle.style.cssText = "position:absolute;top:-14px;left:50%;transform:translateX(-50%);width:60px;height:14px;cursor:ns-resize;border-radius:7px 7px 0 0;background:rgba(60,60,60,0.9);border:1px solid rgba(255,255,255,0.1);border-bottom:none;box-shadow:0 -2px 10px rgba(0,0,0,0.4);transition:width 0.15s,background 0.15s;";
    handle.innerHTML = '<span style="display:flex;justify-content:center;align-items:center;gap:5px;height:100%;pointer-events:none;"><span style="display:block;width:4px;height:4px;border-radius:50%;background:#fff;"></span><span style="display:block;width:4px;height:4px;border-radius:50%;background:#fff;"></span><span style="display:block;width:4px;height:4px;border-radius:50%;background:#fff;"></span></span>';
    handle.addEventListener("mouseenter", function () { handle.style.width = "84px"; handle.style.background = "rgba(255,255,255,0.25)"; });
    handle.addEventListener("mouseleave", function () { handle.style.width = "60px"; handle.style.background = "rgba(60,60,60,0.9)"; });
    el.appendChild(handle);

    handle.addEventListener("pointerdown", function (e) {
      if (e.button !== undefined && e.button !== 0) return;
      e.preventDefault(); e.stopPropagation();
      handle.setPointerCapture(e.pointerId);
      handle.style.background = "rgba(255,255,255,0.30)";
      _dragY = { startY: e.clientY, startBottom: _userBottom };
    });
    handle.addEventListener("pointermove", function (e) {
      if (!_dragY) return;
      var dy = _dragY.startY - e.clientY;
      var nb = _dragY.startBottom + dy;
      var maxB = Math.max(8, getContainerHeight(el) - 56);
      _userBottom = Math.max(8, Math.min(maxB, nb));
      el.style.bottom = _userBottom + "px";
    });
    var endDrag = function (e) { if (!_dragY) return; handle.style.background = "rgba(255,255,255,0.10)"; handle.releasePointerCapture(e.pointerId); _dragY = null; };
    handle.addEventListener("pointerup", endDrag);
    handle.addEventListener("pointercancel", endDrag);
    handle.addEventListener("dblclick", function () { _userBottom = 64; el.style.bottom = "64px"; });

    if (mount) mount.appendChild(el);
    return el;
  }

  function ensureOverlayInDOM() {
    var mount = resolveOverlayMount();
    if (!mount) return;
    if (mount !== overlayMount) {
      if (overlay && overlay.parentNode) overlay.parentNode.removeChild(overlay);
      overlay = null; overlayMount = null;
    }
    if (!overlay) {
      overlay = document.getElementById(OVERLAY_ID);
      if (!overlay || !overlay.parentNode) overlay = createOverlay(mount);
      overlayMount = mount;
    }
    if (!overlay.parentNode && mount) { overlay = createOverlay(mount); overlayMount = mount; }
  }

  /**
   * Show a subtitle line on the overlay.  Skips re-render if unchanged
   * (prevents translation flicker at 60 fps timeupdate).
   */
  function showOverlay(text) {
    ensureOverlayInDOM();
    if (!overlay) return;
    if (!text || !text.trim()) { overlay.style.display = "none"; return; }
    var display = text.replace(/[\r\n]+/g, " ").replace(/\s{2,}/g, " ").trim();
    if (overlay.firstChild.textContent === display && overlay.style.display === "block") return;
    overlay.firstChild.textContent = display;
    overlay.style.display = "block";
    if (TRANSLATE_ENABLED) {
      try { overlay.dispatchEvent(new CustomEvent("vot-subtitle-change", { detail: { text: display }, bubbles: true, composed: true })); } catch (_) {}
    }
  }

  function showTranslation(text) {
    if (!overlay || !overlay.parentNode) return;
    var t = overlay.querySelector(".vot-trans");
    if (t) t.textContent = text || "";
  }

  function showStatus(msg) {
    var el = document.getElementById("vot-vk-sub-status");
    if (!el) {
      el = document.createElement("div");
      el.id = "vot-vk-sub-status";
      el.style.cssText = "position:fixed;top:8px;right:8px;z-index:2147483647;padding:4px 10px;background:rgba(0,0,0,0.6);color:#aaa;font-size:11px;border-radius:4px;pointer-events:none;font-family:monospace;";
      if (document.body) document.body.appendChild(el);
    }
    if (!el.parentNode && document.body) document.body.appendChild(el);
    el.textContent = msg; el.style.display = "block";
    setTimeout(function () { el.style.display = "none"; }, 5000);
  }

  // ═══════════════════════════════════════════════════════════════════════
  // 8. PANEL UI — subtitle list panel (Light DOM)
  // ═══════════════════════════════════════════════════════════════════════
  var _panelEl = null;
  var _panelListEl = null;
  var _panelBaseX = null;
  var _panelBaseY = 80;
  var _panelOffX = 0;
  var _panelOffY = 0;
  var _panelCollapsed = false;
  var _panelScrollLock = false;
  var _panelScrollTimer = null;
  var _highlightTimer = null;
  var _cueRows = [];
  var _dedupedCues = [];
  var _highlightedIdx = -1;

  function applyPanelTransform() {
    if (_panelEl) _panelEl.style.transform = "translate(" + _panelOffX + "px, " + _panelOffY + "px)";
  }

  /** Create a single cue row. */
  function createCueRow(cue, idx) {
    var row = document.createElement("div");
    row.style.cssText = "display:flex;gap:8px;padding:4px 10px;cursor:pointer;border-bottom:1px solid rgba(255,255,255,0.03);transition:background 0.1s;";
    row.setAttribute("data-cue-idx", String(idx));

    var timeSpan = document.createElement("span");
    timeSpan.textContent = formatTime(cue.start);
    timeSpan.style.cssText = "flex-shrink:0;width:42px;color:#888;font-size:11px;font-family:monospace;text-align:right;padding-top:2px;";
    row.appendChild(timeSpan);

    var container = document.createElement("div");
    container.style.cssText = "flex:1;min-width:0;";

    var textSpan = document.createElement("span");
    textSpan.textContent = cue.text;
    textSpan.style.cssText = "display:block;font-size:12px;line-height:1.4;white-space:pre-wrap;word-break:break-word;";
    container.appendChild(textSpan);

    var transSpan = document.createElement("span");
    transSpan.className = "vot-panel-trans";
    transSpan.style.cssText = "display:block;font-size:11px;line-height:1.3;color:#aaa;font-style:italic;white-space:pre-wrap;word-break:break-word;margin-top:1px;";
    container.appendChild(transSpan);

    row.appendChild(container);
    row.addEventListener("click", (function (c) { return function () { if (videoElement && typeof videoElement.currentTime === "number") videoElement.currentTime = c.start; }; })(cue));
    return row;
  }

  /** Full panel rebuild from _dedupedCues. */
  function rebuildPanel() {
    if (!_panelListEl) return;
    _panelListEl.innerHTML = "";
    _cueRows = [];
    _highlightedIdx = -1;
    var cues = _dedupedCues;
    if (!cues.length) {
      var empty = document.createElement("div");
      empty.textContent = "No subtitles loaded";
      empty.style.cssText = "padding:16px;color:#666;text-align:center;";
      _panelListEl.appendChild(empty);
      return;
    }
    for (var i = 0; i < cues.length; i++) { var row = createCueRow(cues[i], i); _panelListEl.appendChild(row); _cueRows.push(row); }
    refreshPanelTranslations();
  }

  /** First render: clean raw cues, build dedup list, kick off translation. */
  function renderCueList() {
    if (!_panelListEl) return;
    _panelListEl.innerHTML = "";
    _cueRows = [];
    if (!activeCues.length) {
      var empty = document.createElement("div");
      empty.textContent = "No subtitles loaded";
      empty.style.cssText = "padding:16px;color:#666;text-align:center;";
      _panelListEl.appendChild(empty);
      return;
    }
    var cues = cleanCues(activeCues);
    _dedupedCues = cues;
    _transUnits = mergeToTranslationUnits(cues);
    translationStart(_transUnits, videoElement ? videoElement.currentTime : 0);
    for (var i = 0; i < cues.length; i++) { var row = createCueRow(cues[i], i); _panelListEl.appendChild(row); _cueRows.push(row); }
  }

  function updatePanelHighlight() {
    if (!videoElement || !_cueRows.length) return;
    var time = videoElement.currentTime, cues = _dedupedCues || activeCues, idx = -1;
    if (cues.length) {
      var lo = 0, hi = cues.length - 1;
      while (lo <= hi) { var mid = (lo + hi) >>> 1; if (time >= cues[mid].start && time < cues[mid].end) { idx = mid; break; } if (time < cues[mid].start) hi = mid - 1; else lo = mid + 1; }
    }
    if (idx === _highlightedIdx) return;
    _highlightedIdx = idx;
    for (var i = 0; i < _cueRows.length; i++) {
      var spans = _cueRows[i].querySelectorAll("span");
      if (i === idx) {
        _cueRows[i].style.background = "rgba(255,255,255,0.15)";
        for (var s = 0; s < spans.length; s++) spans[s].style.color = "#fff";
        if (!_panelScrollLock && _panelListEl) _cueRows[i].scrollIntoView({ block: "center", behavior: "smooth" });
      } else {
        _cueRows[i].style.background = "";
        if (spans.length) spans[0].style.color = "#888";
        if (spans.length > 1) spans[1].style.color = "";
      }
    }
  }

  function refreshPanelTranslations() {
    if (!_cueRows.length) return;
    var cues = _dedupedCues;
    for (var i = 0; i < _cueRows.length; i++) {
      var ts = _cueRows[i].querySelector(".vot-panel-trans");
      if (!ts || ts.textContent) continue;
      var cue = cues[i]; if (!cue) continue;
      var t = cacheGet(cue.text); if (t) ts.textContent = t;
    }
  }

  function refreshPanelTranslationsClear() {
    for (var i = 0; i < _cueRows.length; i++) {
      var ts = _cueRows[i].querySelector(".vot-panel-trans");
      if (ts) ts.textContent = "";
    }
  }

  /** Create a header button with shared styling. */
  function makeHeaderBtn(text, title, width, fontSize, isActive) {
    var btn = document.createElement("button");
    btn.textContent = text; btn.title = title;
    btn.style.cssText = "background:" + (isActive ? "rgba(255,255,255,0.25)" : "rgba(255,255,255,0.1)") + ";border:none;color:" + (isActive ? "#fff" : "#ccc") + ";cursor:pointer;border-radius:4px;width:" + (width || 22) + "px;height:22px;font-size:" + (fontSize || 11) + "px;line-height:1;padding:0;flex-shrink:0;";
    btn.addEventListener("pointerdown", function (e) { e.stopPropagation(); });
    btn.addEventListener("mouseenter", function () { btn.style.background = "rgba(255,255,255,0.25)"; });
    btn.addEventListener("mouseleave", function () { btn.style.background = isActive ? "rgba(255,255,255,0.25)" : "rgba(255,255,255,0.1)"; });
    return btn;
  }

  function createSubtitlePanel() {
    if (_panelEl) return;
    if (_panelBaseX == null) _panelBaseX = window.innerWidth - 360;

    var panel = document.createElement("div");
    panel.id = "vot-vk-sub-panel";
    panel.style.cssText = "position:fixed;top:" + _panelBaseY + "px;left:" + _panelBaseX + "px;z-index:2147483646;width:340px;background:rgba(0,0,0,0.88);color:#fff;border-radius:8px;font-family:Arial,Helvetica,sans-serif;font-size:13px;box-shadow:0 2px 20px rgba(0,0,0,0.5);will-change:transform;display:flex;flex-direction:column;overflow:hidden;";
    applyPanelTransform();

    // ── Header ──
    var header = document.createElement("div");
    header.style.cssText = "display:flex;align-items:center;gap:6px;padding:4px 8px;cursor:move;user-select:none;flex-shrink:0;border-bottom:1px solid rgba(255,255,255,0.08);background:rgba(255,255,255,0.06);";

    var title = document.createElement("span");
    title.setAttribute("data-trans-title", "1");
    title.textContent = "Subtitles";
    title.style.cssText = "flex:1;font-size:12px;color:#aaa;";
    header.appendChild(title);

    // T — translation toggle
    var trBtn = makeHeaderBtn("T", "翻译开关 — 开启/关闭双语翻译", 22, 11, TRANSLATE_ENABLED);
    trBtn.style.fontWeight = "bold";
    trBtn.addEventListener("click", function (e) {
      e.stopPropagation();
      TRANSLATE_ENABLED = !TRANSLATE_ENABLED;
      if (TRANSLATE_ENABLED) {
        trBtn.style.background = "rgba(255,255,255,0.25)"; trBtn.style.color = "#fff";
        translationStart(_transUnits, videoElement ? videoElement.currentTime : 0);
        updatePanelTitle();
      } else {
        trBtn.style.background = "rgba(255,255,255,0.1)"; trBtn.style.color = "#666";
        translationStop();
        updatePanelTitle();
        showTranslation(""); refreshPanelTranslationsClear();
      }
    });
    header.appendChild(trBtn);

    // ⬇ VTT download
    var vttBtn = makeHeaderBtn("⬇", "下载双语字幕 VTT — 原文 + 中文翻译", 28, 13, false);
    vttBtn.addEventListener("click", function (e) { e.stopPropagation(); downloadBilingualVtt(); });
    header.appendChild(vttBtn);

    // SRT download
    var srtBtn = makeHeaderBtn("SRT", "下载双语字幕 SRT — 通用格式，原文 + 中文翻译", 30, 9, false);
    srtBtn.style.fontWeight = "bold";
    srtBtn.addEventListener("click", function (e) { e.stopPropagation(); downloadBilingualSrt(); });
    header.appendChild(srtBtn);

    // ⊙ scroll-to-current
    var scBtn = makeHeaderBtn("⊙", "定位到当前播放的字幕行", 22, 12, false);
    scBtn.addEventListener("click", function (e) { e.stopPropagation(); _panelScrollLock = false; updatePanelHighlight(); });
    header.appendChild(scBtn);

    // −/+ collapse
    var colBtn = makeHeaderBtn("−", "折叠 / 展开字幕列表面板", 22, 14, false);
    colBtn.addEventListener("click", function (e) {
      e.stopPropagation(); _panelCollapsed = !_panelCollapsed;
      colBtn.textContent = _panelCollapsed ? "+" : "−";
      colBtn.title = _panelCollapsed ? "展开字幕列表面板" : "折叠字幕列表面板";
      listContainer.style.display = _panelCollapsed ? "none" : "";
    });
    header.appendChild(colBtn);

    panel.appendChild(header);

    // Panel drag
    var _pDrag = null;
    header.addEventListener("pointerdown", function (e) { if (e.button !== undefined && e.button !== 0) return; e.preventDefault(); header.setPointerCapture(e.pointerId); _pDrag = { x: e.clientX, y: e.clientY, ox: _panelOffX, oy: _panelOffY }; });
    header.addEventListener("pointermove", function (e) { if (!_pDrag) return; _panelOffX = _pDrag.ox + (e.clientX - _pDrag.x); _panelOffY = _pDrag.oy + (e.clientY - _pDrag.y); applyPanelTransform(); });
    header.addEventListener("pointerup",   function () { _pDrag = null; try { header.releasePointerCapture(1); } catch (_) {} });
    header.addEventListener("pointercancel", function () { _pDrag = null; try { header.releasePointerCapture(1); } catch (_) {} });

    // Cue list
    var listContainer = document.createElement("div");
    listContainer.style.cssText = "overflow-y:auto;overflow-x:hidden;max-height:60vh;scroll-behavior:smooth;display:block;";
    listContainer.addEventListener("wheel", function () { _panelScrollLock = true; clearTimeout(_panelScrollTimer); _panelScrollTimer = setTimeout(function () { _panelScrollLock = false; }, 3000); });
    panel.appendChild(listContainer);
    _panelListEl = listContainer;

    document.body.appendChild(panel);
    _panelEl = panel;
    renderCueList();
    if (!_highlightTimer) _highlightTimer = setInterval(updatePanelHighlight, 500);
    log("Panel created");
  }

  window.addEventListener("resize", function () {
    if (!_panelEl) return;
    var cx = _panelBaseX + _panelOffX, cy = _panelBaseY + _panelOffY;
    if (cx + 340 > window.innerWidth) _panelOffX = window.innerWidth - 350 - _panelBaseX;
    if (cy > window.innerHeight - 100) _panelOffY = window.innerHeight - 200 - _panelBaseY;
    applyPanelTransform();
  });

  // ═══════════════════════════════════════════════════════════════════════
  // 9. VIDEO DISCOVERY — Shadow DOM penetration + prototype hooks
  // ═══════════════════════════════════════════════════════════════════════
  var knownShadowRoots = [];

  function collectShadowVideos(host, results) {
    var sr = host.shadowRoot;
    if (sr && sr.querySelectorAll) { var v = sr.querySelectorAll("video"); for (var i = 0; i < v.length; i++) results.push(v[i]); return; }
    for (var s = 0; s < knownShadowRoots.length; s++) {
      var csr = knownShadowRoots[s];
      if (!csr.querySelectorAll) continue;
      if (csr.host === host || !csr.host) { var v2 = csr.querySelectorAll("video"); for (var j = 0; j < v2.length; j++) results.push(v2[j]); }
    }
  }

  function queryAllVideosOnPage() {
    var results = [];
    var light = document.querySelectorAll("video");
    for (var i = 0; i < light.length; i++) results.push(light[i]);
    var vkPlayer = document.querySelector("vk-video-player");
    if (vkPlayer) collectShadowVideos(vkPlayer, results);
    var all = document.querySelectorAll("*");
    for (var j = 0; j < all.length; j++) { if (all[j] !== vkPlayer && all[j].shadowRoot) collectShadowVideos(all[j], results); }
    for (var s = 0; s < knownShadowRoots.length; s++) {
      var csr = knownShadowRoots[s];
      if (!csr.querySelectorAll) continue;
      var cv = csr.querySelectorAll("video");
      for (var c = 0; c < cv.length; c++) { if (results.indexOf(cv[c]) === -1) results.push(cv[c]); }
    }
    return results;
  }

  function findBestVideo() {
    var all = queryAllVideosOnPage();
    if (!all.length) {
      var iframes = document.querySelectorAll("iframe");
      for (var f = 0; f < iframes.length; f++) {
        try { var doc = iframes[f].contentDocument || (iframes[f].contentWindow && iframes[f].contentWindow.document); if (doc) { var iv = doc.querySelectorAll("video"); if (iv.length) return iv[0]; } } catch (_) {}
      }
      return null;
    }
    for (var i = 0; i < all.length; i++) { if (all[i].classList && all[i].classList.contains("player-media")) return all[i]; }
    for (var j = 0; j < all.length; j++) { if (all[j].closest && all[j].closest("vk-video-player, .videoplayer_media, [data-video]")) return all[j]; }
    return all[0];
  }

  function waitForVideo(ms) {
    ms = ms || 15000;
    return new Promise(function (resolve) {
      var start = Date.now();
      var check = function () { var v = findBestVideo(); if (v) resolve(v); else if (Date.now() - start > ms) resolve(null); else setTimeout(check, 300); };
      check();
    });
  }

  function hookAttachShadow() {
    if (Element.prototype.attachShadow.__votHooked) return;
    var orig = Element.prototype.attachShadow;
    var wrapper = function (init) {
      var sr = orig.call(this, init);
      var mode = (init && init.mode) || "open";
      log("Shadow root created (" + mode + ")", this.tagName || "unknown");
      knownShadowRoots.push(sr);
      var timer = null;
      var obs = new MutationObserver(function () { if (timer) return; timer = setTimeout(function () { timer = null; checkVideoChange("shadow mutation"); }, 250); });
      obs.observe(sr, { childList: true, subtree: true });
      setTimeout(function () { checkVideoChange("new shadow root"); }, 50);
      return sr;
    };
    wrapper.__votHooked = true;
    Element.prototype.attachShadow = wrapper;
  }

  function hookVideoPlay() {
    if (HTMLVideoElement.prototype.play.__votPlayHooked) return;
    var orig = HTMLVideoElement.prototype.play;
    var debounce = null;
    var wrapper = function () {
      var v = this;
      if (v !== currentVideo && v.nodeType === 1 && v.classList && v.classList.contains("player-media")) {
        if (debounce) return;
        debounce = setTimeout(function () { debounce = null; }, 500);
        log("Video.play() intercepted:", v);
        currentVideo = v;
        attachToVideo(v);
      }
      return orig.apply(this, arguments);
    };
    wrapper.__votPlayHooked = true;
    HTMLVideoElement.prototype.play = wrapper;
    log("HTMLVideoElement.prototype.play hooked");
  }

  // ═══════════════════════════════════════════════════════════════════════
  // 10. SUBTITLE LOADING — fetch + parse + activate
  // ═══════════════════════════════════════════════════════════════════════
  var activeCues = [];
  var videoElement = null;
  var currentVideo = null;
  var timeUpdateHandler = null;
  var loadedDataHandler = null;
  var _timeUpdateCount = 0;
  var _cueHitCount = 0;
  var _loadingSubtitles = false;
  var _rawVttText = null;
  var _loadedVideoId = null;
  var _lastVideoTime = 0;
  var _lastLoadAttempt = 0;

  function fetchSubtitlesViaGM(url) {
    return new Promise(function (resolve, reject) {
      log("Fetching:", url.substring(0, 80) + "...");
      GM.xmlHttpRequest({
        method: "GET", url: url, responseType: "arraybuffer", timeout: 10000,
        onload: function (r) {
          if (r.status < 200 || r.status >= 400) { reject(new Error("HTTP " + r.status)); return; }
          if (!r.response || r.response.byteLength === 0) { reject(new Error("Empty")); return; }
          var text = decodeTextFromBuffer(r.response);
          text ? resolve(text) : reject(new Error("Decode failed"));
        },
        onerror: function (e) { reject(new Error((e && e.error) || "GM XHR error")); },
        ontimeout: function () { reject(new Error("Timeout")); }
      });
    });
  }

  function getSubtitleUrlsFromPlayer() {
    try {
      var pw = getPageWindow();
      if (typeof pw.Videoview === "undefined") return null;
      var player = pw.Videoview.getPlayerObject && pw.Videoview.getPlayerObject();
      if (!player || !player.vars || !player.vars.subs) return null;
      var subs = Array.isArray(player.vars.subs) ? player.vars.subs : [player.vars.subs];
      var urls = [];
      for (var i = 0; i < subs.length; i++) { if (subs[i].url) urls.push({ url: subs[i].url, lang: subs[i].lang || "unknown", isAuto: !!subs[i].is_auto }); }
      return urls.length ? urls : null;
    } catch (e) { warn("Videoview error:", e); return null; }
  }

  // ── Page state scanning (last-resort fallback) ──
  function normalizeCue(item) {
    if (!item || typeof item !== "object") return null;
    var t = item.text || item.subtitle || item.caption || item.title || null;
    if (!t || !t.trim()) return null;
    var s = parseFloat(item.start != null ? item.start : (item.begin != null ? item.begin : (item.from != null ? item.from : item.ts)));
    var e = parseFloat(item.end != null ? item.end : (item.to != null ? item.to : (item.finish != null ? item.finish : item.stop)));
    if (isNaN(s) || isNaN(e) || e <= s) return null;
    return { start: s, end: e, text: t.trim() };
  }

  function extractCues(obj, results, depth) {
    if (depth > 6 || !obj || typeof obj !== "object") return;
    if (Array.isArray(obj)) {
      var possible = obj.filter(function (i) { return normalizeCue(i); });
      if (possible.length === obj.length && obj.length > 0) { for (var p = 0; p < obj.length; p++) { var cue = normalizeCue(obj[p]); if (cue) results.push(cue); } return; }
      for (var a = 0; a < obj.length; a++) extractCues(obj[a], results, depth + 1);
      return;
    }
    var keys = Object.keys(obj);
    for (var k = 0; k < keys.length; k++) { if (/subtitles?|captions?|tracks?|events?|segments?/i.test(keys[k])) extractCues(obj[keys[k]], results, depth + 1); }
    var c = normalizeCue(obj); if (c) { results.push(c); return; }
    for (var k2 = 0; k2 < keys.length; k2++) extractCues(obj[keys[k2]], results, depth + 1);
  }

  function scanPageStateForSubtitles() {
    var pw = getPageWindow();
    var keys = ["__INITIAL_STATE__", "__PRELOADED_STATE__", "__NEXT_DATA__", "__PAGE_DATA__", "initialState", "pageData", "appState", "windowData", "data", "state"];
    for (var k = 0; k < keys.length; k++) {
      try {
        var val = pw[keys[k]]; if (!val) continue;
        var results = [];
        extractCues(val, results, 0);
        if (results.length > 0) { results.sort(function (a, b) { return a.start - b.start; }); activeCues = cleanCues(results); log("Found", activeCues.length, "cues in page state:", keys[k]); return true; }
      } catch (_) {}
    }
    return false;
  }

  /** Unified subtitle loading: VK player API → track elements → textTracks → page state. */
  async function loadSubtitlesForCurrentVideo() {
    if (!videoElement || _loadingSubtitles) return;
    _loadingSubtitles = true;
    try {
      // 1. VK player API
      var urls = getSubtitleUrlsFromPlayer();
      if (urls && urls.length) {
        var auto = urls.find(function (s) { return s.isAuto; }), target = auto || urls[0];
        log("Player API:", target.lang, "auto:", target.isAuto);
        try {
          var vttText = await fetchSubtitlesViaGM(target.url);
          var cues = parseVtt(vttText);
          if (cues.length) {
            activeCues = cleanCues(cues);
            _rawVttText = vttText;
            _loadedVideoId = (target.url.match(/id=(\d+)/) || [])[1] || "unknown";
            renderCueList();
            _votApplied = false; tryVotBackend(_loadedVideoId);
            showStatus("字幕: " + activeCues.length + " (" + target.lang + ")");
            log("Loaded", activeCues.length, "cues (player API)");
            return;
          }
        } catch (e) { warn("Player API URL failed:", e.message); }
      }

      // 2. <track> elements
      var tracks = videoElement.querySelectorAll("track");
      for (var ti = 0; ti < tracks.length; ti++) {
        var track = tracks[ti]; if (!track.src) continue;
        log("Track element:", track.src.substring(0, 80), track.srclang);
        try {
          var tv = await fetchSubtitlesViaGM(track.src);
          var tc = parseVtt(tv);
          if (tc.length) {
            activeCues = cleanCues(tc);
            _rawVttText = tv;
            _loadedVideoId = (track.src.match(/id=(\d+)/) || [])[1] || "unknown";
            renderCueList();
            _votApplied = false; tryVotBackend(_loadedVideoId);
            showStatus("字幕: " + activeCues.length + " (track)");
            log("Loaded", activeCues.length, "cues (track)");
            return;
          }
        } catch (e) { warn("Track failed:", e.message); }
      }

      // 3. textTracks API
      var ttracks = Array.from(videoElement.textTracks || []);
      for (var tti = 0; tti < ttracks.length; tti++) {
        var tt = ttracks[tti]; if (!["subtitles", "captions", ""].includes(tt.kind)) continue;
        tt.mode = "hidden";
        if (tt.cues && tt.cues.length) {
          activeCues = Array.from(tt.cues).map(function (c) { return { start: c.startTime, end: c.endTime, text: c.text.replace(/<[^>]+>/g, "").trim() }; });
          activeCues.sort(function (a, b) { return a.start - b.start; });
          activeCues = cleanCues(activeCues);
          _rawVttText = serializeMonoVtt(activeCues);
          _loadedVideoId = extractVkVideoId();
          renderCueList();
          _votApplied = false; tryVotBackend(_loadedVideoId);
          showStatus("字幕: " + activeCues.length + " (textTracks)");
          log("Loaded", activeCues.length, "cues (textTracks)");
          return;
        }
      }

      // 4. Page state
      if (scanPageStateForSubtitles()) {
        _rawVttText = serializeMonoVtt(activeCues);
        _loadedVideoId = extractVkVideoId();
        renderCueList();
        _votApplied = false; tryVotBackend(_loadedVideoId);
        showStatus("字幕: " + activeCues.length + " (page state)");
        return;
      }
      log("No subtitles found");
    } finally { _loadingSubtitles = false; }
  }

  // ═══════════════════════════════════════════════════════════════════════
  // 11. CORE — video attach/detach, timeupdate loop
  // ═══════════════════════════════════════════════════════════════════════

  function detachVideo() {
    if (!videoElement) return;
    if (timeUpdateHandler) { videoElement.removeEventListener("timeupdate", timeUpdateHandler); timeUpdateHandler = null; }
    if (loadedDataHandler) { videoElement.removeEventListener("loadeddata", loadedDataHandler); loadedDataHandler = null; }
    videoElement = null;
    activeCues = [];
    _dedupedCues = [];
    _transUnits = [];
    _votApplied = false;
    _votOriginal = null;
    _votTranslated = null;
    showOverlay("");
    log("Detached");
  }

  async function attachToVideo(video) {
    if (!video || videoElement === video) return;
    detachVideo();
    videoElement = video;
    activeCues = [];
    showOverlay("");
    log("Attached:", video);
    await loadSubtitlesForCurrentVideo();
    timeUpdateHandler = function () { if (videoElement) onTimeUpdate(); };
    loadedDataHandler = async function () { log("loadeddata"); await loadSubtitlesForCurrentVideo(); };
    videoElement.addEventListener("timeupdate", timeUpdateHandler);
    videoElement.addEventListener("loadeddata", loadedDataHandler);
  }

  function onTimeUpdate() {
    if (!videoElement) return;
    _timeUpdateCount++;
    var curTime = videoElement.currentTime;

    // Seek detection: rebuild translation queue
    if (Math.abs(curTime - _lastVideoTime) > 2 && _dedupedCues.length) {
      translationStart(_transUnits, curTime);
    }
    _lastVideoTime = curTime;

    // Retry subtitle loading
    var now = Date.now();
    if (!activeCues.length && (now - _lastLoadAttempt) > 2000) { _lastLoadAttempt = now; loadSubtitlesForCurrentVideo(); }

    if (_timeUpdateCount === 1 || _timeUpdateCount % 60 === 0) {
      log("tick #" + _timeUpdateCount, "t=" + curTime.toFixed(1), "cues=" + activeCues.length, "hits=" + _cueHitCount);
    }

    var cue = findCurrentCue(_dedupedCues.length ? _dedupedCues : activeCues, curTime);
    if (cue) { _cueHitCount++; showOverlay(cue.text); }
    else showOverlay("");
  }

  // ── Live translation handler (event from showOverlay) ────────────────
  function onSubtitleChange(e) {
    if (!TRANSLATE_ENABLED) return;
    var text = (e.detail && e.detail.text) || "";
    if (!text || !text.trim()) return;

    var cached = cacheGet(text);
    if (cached !== undefined) { showTranslation(cached); return; }

    translationLive(text, _dedupedCues.length ? _dedupedCues : activeCues);
  }

  // ── Video change observer ─────────────────────────────────────────────
  function checkVideoChange(source) {
    var v = findBestVideo();
    if (v && v !== currentVideo) { currentVideo = v; log("Video changed (" + source + ")"); attachToVideo(v); }
  }

  // ═══════════════════════════════════════════════════════════════════════
  // 12. BOOTSTRAP
  // ═══════════════════════════════════════════════════════════════════════
  function main() {
    var isReboot = !!document.documentElement.getAttribute("data-vot-reboot");
    if (!isReboot) log("Starting VK Subtitle Extractor [document-start]");
    document.documentElement.setAttribute("data-vot-reboot", "1");

    hookAttachShadow();
    hookVideoPlay();
    document.addEventListener("vot-subtitle-change", onSubtitleChange);

    function onBodyReady() {
      var domTimer = null;
      var domObs = new MutationObserver(function () { if (domTimer) return; domTimer = setTimeout(function () { domTimer = null; checkVideoChange("DOM mutation"); }, 250); });
      domObs.observe(document.documentElement, { childList: true, subtree: true });
      log("DOM observer active");

      createSubtitlePanel();
      waitForVideo().then(function (v) { if (v) { currentVideo = v; attachToVideo(v); } else log("No video found, waiting..."); }).catch(function (e) { warn("waitForVideo:", e); });
    }

    if (document.body) onBodyReady();
    else {
      var bodyObs = new MutationObserver(function () { if (document.body) { bodyObs.disconnect(); onBodyReady(); } });
      bodyObs.observe(document.documentElement, { childList: true, subtree: true });
    }
  }

  try { main(); } catch (e) { warn("init error:", e); }
})();