// ==UserScript==
// @name         学习通一键导出
// @namespace    local.xxt.userscript
// @version      1.3.0
// @description  学习通作业/考试页一键导出 Word(.docx)：图片位置与原插件一致；OCR 仅用于纯文字图，公式/图形自动留原图
// @author       祁桉
// @match        *://*.chaoxing.com/*
// @match        *://*.cldisk.com/*
// @grant        GM_xmlhttpRequest
// @grant        GM.xmlHttpRequest
// @connect      chaoxing.com
// @connect      cldisk.com
// @connect      cdn.jsdelivr.net
// @connect      tessdata.projectnaptha.com
// @connect      unpkg.com
// @connect      *
// @require      https://cdn.jsdelivr.net/npm/tesseract.js@5.1.1/dist/tesseract.min.js
// @run-at       document-idle
// ==/UserScript==
//
// 由原 Edge 扩展（content.js + native_host.py）转换而来，排版规则逐条对齐原版：
//  - 题干有内嵌图 -> 图文按原顺序同一段；无内嵌图 -> 题干成段后再单独插图（不再重复插）
//  - 题干内嵌图高 0.45"；独立题图 <=2.0"x0.9"；选项/答案图高 0.65"、宽<=1.8"
//  - 图片默认保留原图；OCR 仅当识别质量达标（置信度足够、像正常文字）才用文字，否则留原图

(() => {
  if (window.__xxtExporterInjected) return;
  window.__xxtExporterInjected = true;

  const sleep = (ms) => new Promise((r) => setTimeout(r, ms));
  const TYPES = '单选题|多选题|判断题|填空题|简答题|名词解释|论述题|案例分析';

  async function scrollLoad() {
    let lastH = 0;
    for (let i = 0; i < 12; i++) {
      window.scrollTo(0, document.documentElement.scrollHeight || document.body.scrollHeight);
      await sleep(400);
      const h = document.documentElement.scrollHeight || document.body.scrollHeight;
      if (h === lastH) break;
      lastH = h;
    }
    window.scrollTo(0, 0);
    await sleep(300);
  }

  function parseQuestionsFromText(fullText) {
    const normalized = (fullText || '').replace(/\u00a0/g, ' ').replace(/\r\n?/g, '\n');
    const headerRe = new RegExp('\\n(?=\\s*\\d{1,3}\\s*[.、．:：](?!\\d)\\s*(?:\\(?(?:' + TYPES + ')\\)?)?)', 'g');
    const parts = normalized.split(headerRe).map((s) => s.trim()).filter(Boolean);

    const questions = [];
    for (const part of parts) {
      const q = parseQuestionPart(part);
      if (!q) continue;
      const hasType = new RegExp('^(?:' + TYPES + ')$').test(q.type);
      if (q.options.length || hasType || q.answer || q.myAnswer) {
        questions.push(q);
      }
    }
    return questions;
  }

  function extractTextAnswer(part, labels) {
    const m = part.match(new RegExp(labels + '[:：]'));
    if (!m) return '';
    const segment = part.slice(m.index + m[0].length);
    const lines = segment.split(/\n+/).map((s) => s.trim());
    for (const line of lines) {
      if (!line) continue;
      if (/^\d+分$/.test(line)) continue;
      if (/^(我的答案|正确答案|参考答案|标准答案|AI讲解|知识点|排除法)/.test(line)) break;
      return line;
    }
    return '';
  }

  function parseQuestionPart(part) {
    const lines = part.split(/\n+/).map((s) => s.trim());
    if (!lines.length) return null;

    const header = lines[0] || '';
    const hm = header.match(/^\s*(\d{1,3})\s*[.、．:：](?!\d)\s*(?:\(([^)]*)\)\s*)?(.*)$/);
    if (!hm) return null;
    const number = parseInt(hm[1], 10);

    let type = (hm[2] || '').trim();
    let headerRest = (hm[3] || '').trim();

    if (type) {
      const tm = type.match(new RegExp('(' + TYPES + ')'));
      type = tm ? tm[1] : type;
    }
    if (!type) {
      const tm = headerRest.match(new RegExp('^(' + TYPES + ')'));
      if (tm) {
        type = tm[1];
        headerRest = headerRest.slice(tm[0].length).trim();
      }
    }
    if (!type) type = '题目';

    const options = [];
    const stemLines = headerRest ? [headerRest] : [];
    let myAnswer = '';
    let myText = '';
    let correctAnswer = '';
    let correctText = '';
    let state = 'stem';
    let currentOption = null;

    const stopRe = /^\d+分$|^AI讲解$|^知识点[:：]?|^排除法$|^[一二三四五六七八九十]+[.、]/;

    for (let i = 1; i < lines.length; i++) {
      const line = lines[i];

      if (stopRe.test(line) || /^(答题卡|上一题|下一题|收藏|标记|纠错|展开|收起|题目列表|试卷列表)$/.test(line)) {
        break;
      }

      const myM = line.match(/^我的答案[:：]\s*([A-H])?/i);
      if (myM) {
        if (myM[1]) myAnswer = myM[1].toUpperCase();
        state = 'my';
        let j = i + 1;
        while (j < lines.length && lines[j].startsWith(':')) {
          if (!myText) myText = lines[j].slice(1).replace(/;+$/g, '').trim();
          j++;
        }
        i = j - 1;
        continue;
      }

      const correctM = line.match(/^(正确答案|参考答案|标准答案)[:：]\s*([A-H])?/i);
      if (correctM) {
        if (correctM[2]) correctAnswer = correctM[2].toUpperCase();
        state = 'correct';
        let j = i + 1;
        while (j < lines.length && lines[j].startsWith(':')) {
          if (!correctText) correctText = lines[j].slice(1).replace(/;+$/g, '').trim();
          j++;
        }
        i = j - 1;
        continue;
      }

      if (/^(答案解析|解析)[:：]/.test(line)) {
        continue;
      }

      const optionM = line.match(/^([A-H])[.、．:：)]\s*(.*)$/);
      if (optionM) {
        const letter = optionM[1].toUpperCase();
        const optText = (optionM[2] || '').trim();
        currentOption = optText ? `${letter}. ${optText}` : `${letter}. `;
        options.push(currentOption);
        state = 'options';
        continue;
      }

      if (state === 'options' && currentOption) {
        const appended = (options[options.length - 1].endsWith(' ') ? '' : ' ') + line;
        options[options.length - 1] = options[options.length - 1] + appended;
        continue;
      }

      if (line) {
        stemLines.push(line);
      }
    }

    let stem = stemLines.join(' ').trim();

    if (!myAnswer) {
      myAnswer = extractTextAnswer(part, '我的答案');
    }
    if (!correctAnswer) {
      correctAnswer = extractTextAnswer(part, '正确答案|参考答案|标准答案');
    }

    return {
      number,
      type,
      stem,
      options,
      answer: correctAnswer || '',
      myAnswer: myAnswer || '',
      analysis: ''
    };
  }

  function buildStemItems(h) {
    const qt = h.querySelector('.qtContent') || h.querySelector('.qtContent.workTextWrap');
    if (!qt) return null;
    const items = [];
    let buf = '';
    const flush = () => {
      const t = buf.replace(/\s+/g, ' ').trim();
      if (t) items.push({ type: 'text', text: t });
      buf = '';
    };
    const walk = (el) => {
      for (const child of el.childNodes) {
        if (child.nodeType === Node.TEXT_NODE) {
          buf += child.textContent;
        } else if (child.nodeType === Node.ELEMENT_NODE) {
          if (child.tagName === 'IMG') {
            flush();
            const src = child.getAttribute('data-original') || child.currentSrc || child.src || '';
            if (src) items.push({ type: 'image', url: src, data_url: '' });
          } else if (child.tagName === 'BR') {
            buf += '\n';
          } else {
            walk(child);
          }
        }
      }
    };
    walk(qt);
    flush();
    return items.length ? items : null;
  }

  function collectImagesByNumber() {
    const map = {};
    const heads = document.querySelectorAll('h3.mark_name');
    for (const h of heads) {
      const text = (h.innerText || '').trim();
      const m = text.match(/^\s*(\d{1,3})\s*[.、．:：]/);
      if (!m) continue;
      const num = parseInt(m[1], 10);

      const questionImages = [];
      h.querySelectorAll('img').forEach((img) => {
        const src = img.getAttribute('data-original') || img.currentSrc || img.src || '';
        if (src) questionImages.push({ url: src, data_url: '' });
      });

      const answerImages = [];
      const optionImagesByLetter = {};
      const seenAnswer = new Set();
      const seenOption = new Set();
      const answerSel = 'dd.rightAnswerContent.workTextWrap, dl.mark_fill.colorGreen';
      const myAnswerSel = 'dd.textwrap.stuAnswerContent.reserve-newline, dl.mark_fill.colorDeep';

      let node = h.nextElementSibling;
      while (node && !(node.tagName === 'H3' && node.classList.contains('mark_name'))) {
        const answerContainers = node.querySelectorAll(answerSel);
        answerContainers.forEach((container) => {
          container.querySelectorAll('img').forEach((img) => {
            const src = img.getAttribute('data-original') || img.currentSrc || img.src || '';
            if (src && !seenAnswer.has(src)) {
              seenAnswer.add(src);
              answerImages.push({ url: src, data_url: '' });
            }
          });
        });

        const optionLis = node.querySelectorAll('li.workTextWrap');
        optionLis.forEach((li) => {
          const t = (li.innerText || '').trim();
          const lm = t.match(/^\s*([A-H])[.、．:：)]/);
          if (!lm) return;
          const letter = lm[1].toUpperCase();
          li.querySelectorAll('img').forEach((img) => {
            const src = img.getAttribute('data-original') || img.currentSrc || img.src || '';
            if (!src || seenOption.has(src)) return;
            seenOption.add(src);
            if (!optionImagesByLetter[letter]) optionImagesByLetter[letter] = [];
            optionImagesByLetter[letter].push({ url: src, data_url: '' });
          });
        });

        node = node.nextElementSibling;
      }

      const stemItems = buildStemItems(h);

      if (questionImages.length || answerImages.length || Object.keys(optionImagesByLetter).length || stemItems) {
        map[num] = { questionImages, answerImages, optionImagesByLetter, stemItems };
      }
    }
    return map;
  }

  async function blobToDataURL(blob) {
    return new Promise((resolve, reject) => {
      const fr = new FileReader();
      fr.onload = () => resolve(fr.result);
      fr.onerror = reject;
      fr.readAsDataURL(blob);
    });
  }

  async function enrichImageData(img) {
    if (img.data_url) return;
    let src = img.url || '';
    if (!src || src.startsWith('data:')) return;
    if (src.startsWith('//')) src = location.protocol + src;
    try {
      const resp = await fetch(src, { credentials: 'include' });
      if (resp.ok) {
        const blob = await resp.blob();
        img.data_url = await blobToDataURL(blob);
      }
    } catch (e) {
      img.data_url = '';
    }
  }

  async function attachImages(questions) {
    const imageMap = collectImagesByNumber();
    if (!Object.keys(imageMap).length) return questions;
    for (const q of questions) {
      const entry = imageMap[q.number];
      if (!entry) continue;
      const qImgs = entry.questionImages || [];
      const aImgs = entry.answerImages || [];
      const oMap = entry.optionImagesByLetter || {};
      const oImgs = Object.values(oMap).flat();
      for (const img of qImgs.concat(aImgs, oImgs)) {
        await enrichImageData(img);
      }
      q.images = qImgs;
      q.answer_images = aImgs;
      q.option_images_by_letter = oMap;
      if (entry.stemItems) q.stem_items = entry.stemItems;
    }
    return questions.filter((q) => q.stem || q.options.length || q.answer || (q.images && q.images.length) || (q.answer_images && q.answer_images.length) || (q.option_images_by_letter && Object.keys(q.option_images_by_letter).length));
  }

  function guessCourse() {
    const selectors = ['.breadcrumb', '.crumbs', '.catalog_title', '.chapter', 'h1', '.title'];
    for (const s of selectors) {
      const el = document.querySelector(s);
      const t = el && el.innerText ? el.innerText.trim() : '';
      if (t && t.length < 80) return t;
    }
    const m = (document.title || '').match(/^(.+?)[-_—]\s*学习通/);
    if (m) return m[1].trim();
    return '';
  }

  function guessAssignmentName(fullText) {
    const m = (fullText || '').match(/(?:考试详情|作业详情)\s*\n\s*(.+?)\s*\n\s*题量/);
    if (m && m[1]) return m[1].trim();
    return guessCourse();
  }

  function guessAssignmentKind(fullText) {
    const t = fullText || '';
    if (/考试详情|考试时间/.test(t)) return '考试';
    if (/作业详情|作答时间/.test(t)) return '作业';
    return '作业';
  }

  async function extract() {
    await scrollLoad();
    const fullText = document.body.innerText || '';
    let questions = parseQuestionsFromText(fullText);
    questions = await attachImages(questions);

    if (!questions.length) {
      return { ok: false, error: '没有解析到题目，请确认已打开学习通作业/考试页面并完全加载。' };
    }

    const assignmentName = guessAssignmentName(fullText);
    const assignmentKind = guessAssignmentKind(fullText);

    return {
      ok: true,
      title: document.title || '',
      course: guessCourse(),
      assignment_name: assignmentName,
      assignment_kind: assignmentKind,
      page_url: location.href,
      questions,
};
  }

  // ================================================================
  // 【补丁 1】图片获取：绕过 CORS
  // 原插件真正靠的是 native_host.py 里带 Referer 的 urllib 下载；
  // 油猴里 fetch 跨域会被拦，导致图片只剩一个网址。这里用 GM_xmlhttpRequest。
  // ================================================================
  async function enrichImageData(img) {
    if (!img || img.data_url) return;
    let src = img.url || '';
    if (!src || src.startsWith('data:')) return;
    if (src.startsWith('//')) src = location.protocol + src;
    try { src = new URL(src, location.href).href; } catch (e) {}

    const gm = (typeof GM_xmlhttpRequest !== 'undefined') ? GM_xmlhttpRequest
      : (typeof GM !== 'undefined' && GM && GM.xmlHttpRequest) ? GM.xmlHttpRequest : null;

    if (gm) {
      const got = await new Promise((resolve) => {
        try {
          gm({
            method: 'GET', url: src, responseType: 'blob',
            headers: { Referer: location.href },
            withCredentials: true, timeout: 30000,
            onload: async (res) => {
              try {
                if (res && res.status >= 200 && res.status < 300 && res.response) {
                  if (res.response instanceof Blob) return resolve(await blobToDataURL(res.response));
                  if (res.response instanceof ArrayBuffer) return resolve(await blobToDataURL(new Blob([res.response])));
                }
                resolve('');
              } catch (e) { resolve(''); }
            },
            onerror: () => resolve(''), ontimeout: () => resolve('')
          });
        } catch (e) { resolve(''); }
      });
      if (got) { img.data_url = got; return; }
    }

    try {
      const resp = await fetch(src, { credentials: 'include' });
      if (resp && resp.ok) img.data_url = await blobToDataURL(await resp.blob());
    } catch (e) {}
  }

  // ================================================================
  // 【补丁 2】图片文字识别 OCR（带质量闸门）
  // 只有「像正常文字」时才用 OCR 结果；公式 / 图形 / 化学式 / 表格 等
  // 会被闸门判定为不合格，自动改为放原图（和原版"直接留原图"的结果一致）。
  // ================================================================
  const OCR_MIN_CONF = 70;          // 平均置信度低于此值 -> 判为图形/公式，用原图
  const OCR_MIN_CHARS = 4;          // 有效字符太少 -> 用原图
  const OCR_MAX_SYMBOL_RATIO = 0.4; // 符号占比过高（公式/化学式/图形）-> 用原图

  let _ocrWorker = null, _ocrLoading = null;

  async function getOcrWorker() {
    if (_ocrWorker) return _ocrWorker;
    if (!_ocrLoading) {
      _ocrLoading = (async () => {
        if (typeof Tesseract === 'undefined') throw new Error('OCR 组件未加载（可能没联网）');
        const w = await Tesseract.createWorker('chi_sim+eng');
        _ocrWorker = w;
        return w;
      })().catch((e) => { _ocrLoading = null; throw e; });
    }
    return _ocrLoading;
  }

  function collectOcrTargets(res) {
    const items = [], seen = new Set();
    const push = (im) => {
      if (!im) return;
      const k = im.data_url || '';
      if (!k.startsWith('data:') || seen.has(k)) return;
      seen.add(k); items.push(im);
    };
    (res.questions || []).forEach((q) => {
      (q.stem_items || []).forEach((it) => { if (it.type === 'image') push(it); });
      (q.images || []).forEach(push);
      const om = q.option_images_by_letter || {};
      Object.keys(om).forEach((k) => (om[k] || []).forEach(push));
      (q.answer_images || []).forEach(push);
    });
    return items;
  }

  function ocrQualityOk(out) {
    const d = (out && out.data) || {};
    const raw = (((d.text == null ? '' : d.text)) + '').trim();
    const compact = raw.replace(/\s+/g, '');
    const alnum = compact.replace(/[^\u4e00-\u9fa5A-Za-z0-9]/g, '');
    const symbolRatio = compact.length ? (1 - (alnum.length / compact.length)) : 1;
    const conf = (typeof d.confidence === 'number') ? d.confidence : 0;
    const ok = !!raw && conf >= OCR_MIN_CONF && alnum.length >= OCR_MIN_CHARS && symbolRatio <= OCR_MAX_SYMBOL_RATIO;
    return { ok: ok, text: raw.replace(/\s+/g, ' '), conf: Math.round(conf), symbolRatio: symbolRatio };
  }

  async function runOcrOnImages(res, onProgress) {
    const targets = collectOcrTargets(res);
    if (!targets.length) return { total: 0, ok: 0, skipped: 0, failed: false };
    let worker;
    try { worker = await getOcrWorker(); }
    catch (e) { return { total: targets.length, ok: 0, skipped: 0, failed: true, error: (e && e.message) || String(e) }; }
    let ok = 0;
    for (let i = 0; i < targets.length; i++) {
      try {
        const out = await worker.recognize(targets[i].data_url);
        const q = ocrQualityOk(out);
        if (q.ok) { targets[i].ocr_text = q.text; targets[i].ocr_conf = q.conf; ok++; }
      } catch (e) {}
      if (onProgress) onProgress(i + 1, targets.length);
    }
    return { total: targets.length, ok: ok, skipped: targets.length - ok, failed: false };
  }


  // ================================================================
  // userscript 版：界面 + 浏览器内导出
  // 导出 Word 使用「自建最小 OOXML(.docx) 打包器」，图片按标准内嵌，
  // 不依赖 nativeMessaging / 内置 Python / python-docx / RapidOCR。
  // ================================================================
  const CFG = { includeOptions: true, includeAnswer: false, includeImages: true, includeOcr: true };
  let FAB = null, PANEL = null, TIP = null;

  const esc = (s) => String(s == null ? '' : s)
    .replace(/&/g, '&amp;').replace(/</g, '&lt;').replace(/>/g, '&gt;').replace(/"/g, '&quot;');
  const imgSrc = (im) => (im && (im.data_url || im.url)) || '';
  const nap = (ms) => new Promise((r) => setTimeout(r, ms));
  const letterOf = (s) => { const t = (s || '').trim(); return t ? t[0].toUpperCase() : ''; };

  function stamp() {
    const d = new Date(); const p = (n) => String(n).padStart(2, '0');
    return `${d.getFullYear()}${p(d.getMonth() + 1)}${p(d.getDate())}_${p(d.getHours())}${p(d.getMinutes())}`;
  }
  function safeName(s) {
    return (s || '').replace(/[\\/:*?"<>|\r\n\t]/g, '_').replace(/^[\s._]+|[\s._]+$/g, '').slice(0, 80);
  }
  function meta(res) {
    const kind = res.assignment_kind || '作业';
    const name = res.assignment_name || res.course || ('学习通' + kind);
    return { kind, name, title: name + '（' + kind + '）' };
  }

  // ---------------- 通用下载 ----------------
  function downloadBlob(filename, blob) {
    const a = document.createElement('a');
    a.href = URL.createObjectURL(blob);
    a.download = filename;
    document.body.appendChild(a); a.click();
    setTimeout(() => { URL.revokeObjectURL(a.href); a.remove(); }, 1500);
  }
  function downloadText(filename, content, mime) {
    downloadBlob(filename, new Blob(['\ufeff' + content], { type: mime + ';charset=utf-8' }));
  }

  // ---------------- Markdown / 文本 ----------------
  function buildMarkdown(res) {
    const qs = res.questions || []; const m = meta(res);
    const out = ['# ' + m.title, '', '> 共 ' + qs.length + ' 题 · ' + new Date().toLocaleString(), ''];
    qs.forEach((q, i) => {
      out.push('## ' + (i + 1) + '. ' + (q.type || '题目'));
      out.push(q.stem || '（图片题）');
      if (CFG.includeImages) (q.images || []).forEach((im) => { const s = imgSrc(im); if (s) out.push('![](' + s + ')'); });
      if (CFG.includeOptions) (q.options || []).forEach((o) => {
        out.push('- ' + o);
        if (CFG.includeImages) (((q.option_images_by_letter || {})[letterOf(o)]) || []).forEach((im) => { const s = imgSrc(im); if (s) out.push('  ![](' + s + ')'); });
      });
      if (CFG.includeAnswer) out.push('> 答案：' + ((q.answer || '').trim() || '未显示答案'));
      out.push('');
    });
    return out.join('\n');
  }
  function buildText(res) {
    const qs = res.questions || [];
    const out = [meta(res).title, '共 ' + qs.length + ' 题', ''];
    qs.forEach((q, i) => {
      out.push((i + 1) + '.【' + (q.type || '题目') + '】' + (q.stem || ''));
      if (CFG.includeOptions) (q.options || []).forEach((o) => out.push('    ' + o));
      if (CFG.includeAnswer) out.push('    答案：' + ((q.answer || '').trim() || '未显示答案'));
      out.push('');
    });
    return out.join('\n');
  }

  // ---------------- 最小 ZIP（store，无压缩） ----------------
  let _crcTable = null;
  function crc32(u8) {
    if (!_crcTable) {
      _crcTable = new Uint32Array(256);
      for (let n = 0; n < 256; n++) { let c = n; for (let k = 0; k < 8; k++) c = (c & 1) ? (0xEDB88320 ^ (c >>> 1)) : (c >>> 1); _crcTable[n] = c >>> 0; }
    }
    let crc = 0xFFFFFFFF;
    for (let i = 0; i < u8.length; i++) crc = (crc >>> 8) ^ _crcTable[(crc ^ u8[i]) & 0xFF];
    return (crc ^ 0xFFFFFFFF) >>> 0;
  }
  function zipStore(entries) {
    const enc = new TextEncoder();
    const u16 = (n) => [n & 0xFF, (n >>> 8) & 0xFF];
    const u32 = (n) => [n & 0xFF, (n >>> 8) & 0xFF, (n >>> 16) & 0xFF, (n >>> 24) & 0xFF];
    const d = new Date();
    const dt = ((d.getHours() << 11) | (d.getMinutes() << 5) | (d.getSeconds() >> 1)) & 0xFFFF;
    const dd = (((d.getFullYear() - 1980) << 9) | ((d.getMonth() + 1) << 5) | d.getDate()) & 0xFFFF;
    const parts = [], central = [];
    let offset = 0;
    for (const e of entries) {
      const nb = enc.encode(e.name), data = e.data, crc = crc32(data);
      const lh = new Uint8Array([].concat(
        u32(0x04034b50), u16(20), u16(0x0800), u16(0), u16(dt), u16(dd),
        u32(crc), u32(data.length), u32(data.length), u16(nb.length), u16(0)));
      parts.push(lh, nb, data);
      central.push({ nb, crc, size: data.length, offset });
      offset += lh.length + nb.length + data.length;
    }
    const cdParts = [];
    let cdSize = 0;
    for (const c of central) {
      const cd = new Uint8Array([].concat(
        u32(0x02014b50), u16(20), u16(20), u16(0x0800), u16(0), u16(dt), u16(dd),
        u32(c.crc), u32(c.size), u32(c.size), u16(c.nb.length), u16(0), u16(0), u16(0), u16(0), u32(0), u32(c.offset)));
      cdParts.push(cd, c.nb);
      cdSize += cd.length + c.nb.length;
    }
    const eocd = new Uint8Array([].concat(
      u32(0x06054b50), u16(0), u16(0), u16(central.length), u16(central.length), u32(cdSize), u32(offset), u16(0)));
    let total = eocd.length;
    for (const p of parts) total += p.length;
    for (const p of cdParts) total += p.length;
    const out = new Uint8Array(total);
    let pos = 0;
    for (const p of parts.concat(cdParts, [eocd])) { out.set(p, pos); pos += p.length; }
    return out;
  }

  // ---------------- 图片工具 ----------------
  function b64ToU8(b64) {
    const bin = atob(b64);
    const u8 = new Uint8Array(bin.length);
    for (let i = 0; i < bin.length; i++) u8[i] = bin.charCodeAt(i);
    return u8;
  }
  function parseDataUrl(url) {
    const m = /^data:image\/(png|jpe?g|gif|webp|bmp);base64,(.*)$/i.exec(url || '');
    if (!m) return null;
    const ext = m[1].toLowerCase().replace('jpeg', 'jpg');
    try { return { ext: ext, u8: b64ToU8(m[2]) }; } catch (e) { return null; }
  }
  function imageSize(u8, ext) {
    try {
      if (ext === 'png') {
        if (u8.length < 24) return null;
        const w = (u8[16] << 24) | (u8[17] << 16) | (u8[18] << 8) | u8[19];
        const h = (u8[20] << 24) | (u8[21] << 16) | (u8[22] << 8) | u8[23];
        return (w > 0 && h > 0) ? { w: w, h: h } : null;
      }
      if (ext === 'gif') {
        if (u8.length < 10) return null;
        const w = u8[6] | (u8[7] << 8), h = u8[8] | (u8[9] << 8);
        return (w > 0 && h > 0) ? { w: w, h: h } : null;
      }
      if (ext === 'jpg') {
        let i = 2;
        while (i + 9 < u8.length) {
          if (u8[i] !== 0xFF) { i++; continue; }
          const mk = u8[i + 1];
          if (mk === 0xD8 || mk === 0x01 || (mk >= 0xD0 && mk <= 0xD7)) { i += 2; continue; }
          const len = (u8[i + 2] << 8) | u8[i + 3];
          if (mk >= 0xC0 && mk <= 0xCF && mk !== 0xC4 && mk !== 0xC8 && mk !== 0xCC) {
            const h = (u8[i + 5] << 8) | u8[i + 6], w = (u8[i + 7] << 8) | u8[i + 8];
            return (w > 0 && h > 0) ? { w: w, h: h } : null;
          }
          i += 2 + len;
        }
      }
      if (ext === 'webp') {
        if (u8.length < 30) return null;
        if (u8[12] === 0x56 && u8[13] === 0x50 && u8[14] === 0x38 && u8[15] === 0x58) {
          const w = 1 + (u8[24] | (u8[25] << 8) | (u8[26] << 16));
          const h = 1 + (u8[27] | (u8[28] << 8) | (u8[29] << 16));
          return { w: w, h: h };
        }
      }
    } catch (e) {}
    return null;
  }

  // ---------------- OOXML 片段 ----------------
  const PTSZ = { title: 28, stem: 22, body: 20 };
  function runXml(text, o) {
    o = o || {};
    const font = o.font || '宋体';
    return '<w:r><w:rPr><w:rFonts w:ascii="' + font + '" w:eastAsia="' + font + '" w:hAnsi="' + font + '"/>' +
      (o.bold ? '<w:b/>' : '') + (o.color ? '<w:color w:val="' + o.color + '"/>' : '') +
      '<w:sz w:val="' + (o.size || PTSZ.body) + '"/><w:szCs w:val="' + (o.size || PTSZ.body) + '"/></w:rPr>' +
      '<w:t xml:space="preserve">' + esc(text) + '</w:t></w:r>';
  }
  function pXml(text, o) {
    o = o || {};
    const ppr = '<w:pPr>' +
      '<w:spacing' + (o.before != null ? ' w:before="' + o.before + '"' : '') + (o.after != null ? ' w:after="' + o.after + '"' : '') + ' w:line="336" w:lineRule="auto"/>' +
      (o.indent ? '<w:ind w:left="' + o.indent + '"/>' : '') +
      (o.align ? '<w:jc w:val="' + o.align + '"/>' : '') +
      '</w:pPr>';
    return '<w:p>' + ppr + runXml(text, o) + '</w:p>';
  }
  function drawingRun(im) {
    return '<w:r><w:drawing><wp:inline distT="0" distB="0" distL="0" distR="0">' +
      '<wp:extent cx="' + im.cx + '" cy="' + im.cy + '"/>' +
      '<wp:docPr id="' + im.seq + '" name="Picture ' + im.seq + '"/>' +
      '<a:graphic><a:graphicData uri="http://schemas.openxmlformats.org/drawingml/2006/picture">' +
      '<pic:pic><pic:nvPicPr><pic:cNvPr id="' + im.seq + '" name="image' + im.seq + '"/><pic:cNvPicPr/></pic:nvPicPr>' +
      '<pic:blipFill><a:blip r:embed="' + im.rid + '"/><a:stretch><a:fillRect/></a:stretch></pic:blipFill>' +
      '<pic:spPr><a:xfrm><a:off x="0" y="0"/><a:ext cx="' + im.cx + '" cy="' + im.cy + '"/></a:xfrm>' +
      '<a:prstGeom prst="rect"><a:avLst/></a:prstGeom></pic:spPr>' +
      '</pic:pic></a:graphicData></a:graphic></wp:inline></w:drawing></w:r>';
  }
  function drawingPara(im) {
    return '<w:p><w:pPr><w:spacing w:before="60" w:after="60" w:line="336" w:lineRule="auto"/><w:ind w:left="360"/></w:pPr>' + drawingRun(im) + '</w:p>';
  }

  // ---------------- 生成 .docx ----------------
  function buildDocx(res) {
    const qs = res.questions || [];
    const m = meta(res);
    const media = [], rels = [];
    let seq = 0;

    const IN = 914400;
    function addImg(imEl, mode) {
      const parsed = parseDataUrl(imgSrc(imEl));
      if (!parsed) return null;
      seq++;
      const fname = 'image' + seq + '.' + parsed.ext;
      const rid = 'rIdImg' + seq;
      media.push({ name: 'word/media/' + fname, data: parsed.u8 });
      rels.push({ id: rid, target: 'media/' + fname });
      const nat = imageSize(parsed.u8, parsed.ext) || { w: 640, h: 400 };
      const aspect = (nat.w > 0 && nat.h > 0) ? (nat.w / nat.h) : 1.6;
      let wi, hi;
      if (mode === 'stem') {
        hi = 0.45; wi = hi * aspect;
        if (wi > 6.0) { wi = 6.0; hi = wi / aspect; }
      } else if (mode === 'option' || mode === 'answer') {
        hi = 0.65; wi = hi * aspect;
        if (wi > 1.8) { wi = 1.8; hi = wi / aspect; }
      } else {
        wi = 2.0; hi = wi / aspect;
        if (hi > 0.9) { hi = 0.9; wi = hi * aspect; }
      }
      return { rid: rid, cx: Math.max(9525, Math.round(wi * IN)), cy: Math.max(9525, Math.round(hi * IN)), seq: seq };
    }

    const body = [];
    body.push(pXml(m.title, { bold: true, size: PTSZ.title, font: '微软雅黑', align: 'center', after: 200 }));

    qs.forEach((q, i) => {
      if (q.stem_items && q.stem_items.length) {
        const runs = [runXml((i + 1) + '.【' + (q.type || '题目') + '】', { bold: true, size: PTSZ.stem })];
        q.stem_items.forEach((it) => {
          if (it.type === 'image') {
            if (it.ocr_text) runs.push(runXml('【图片文字】' + it.ocr_text, { size: PTSZ.stem }));
            else { const im = addImg(it, 'stem'); if (im) runs.push(drawingRun(im)); }
          } else runs.push(runXml(it.text || '', { size: PTSZ.stem }));
        });
        body.push('<w:p><w:pPr><w:spacing w:before="160" w:after="80" w:line="336" w:lineRule="auto"/></w:pPr>' + runs.join('') + '</w:p>');
      } else {
        body.push(pXml((i + 1) + '.【' + (q.type || '题目') + '】' + (q.stem || '（图片题，见下方原图）'), { bold: true, size: PTSZ.stem, before: 160, after: 80 }));
        if (CFG.includeImages) {
          (q.images || []).forEach((im) => {
            if (im && im.ocr_text) {
              body.push(pXml('【图片文字】' + im.ocr_text, { size: PTSZ.body, color: '333333', indent: 360, after: 80 }));
              return;
            }
            const r = addImg(im, 'block');
            if (r) body.push(drawingPara(r));
            else if (im && im.url) body.push(pXml('（图片：' + im.url + '）', { size: 18, color: '888888', indent: 360, after: 60 }));
          });
        }
      }
      if (CFG.includeOptions) {
        (q.options || []).forEach((o) => {
          body.push(pXml(o, { size: PTSZ.body, indent: 360, after: 40 }));
          if (CFG.includeImages) {
            (((q.option_images_by_letter || {})[letterOf(o)]) || []).forEach((im) => {
              if (im && im.ocr_text) {
                body.push(pXml('【图片文字】' + im.ocr_text, { size: PTSZ.body, color: '333333', indent: 360, after: 40 }));
                return;
              }
              const r = addImg(im, 'option');
              if (r) body.push(drawingPara(r));
            });
          }
        });
      }
      if (CFG.includeAnswer) {
        const ans = (q.answer || '').trim();
        body.push(pXml('答案：' + (ans || '未显示答案'), { bold: true, size: PTSZ.body, color: '0A7A2F', indent: 360, before: 40, after: 80 }));
      }
      if (CFG.includeImages) {
        (q.answer_images || []).forEach((im) => {
          if (im && im.ocr_text) {
            body.push(pXml('【图片文字】' + im.ocr_text, { size: PTSZ.body, color: '333333', indent: 360, after: 60 }));
            return;
          }
          const r = addImg(im, 'answer');
          if (r) body.push(drawingPara(r));
        });
      }
      if (i !== qs.length - 1) body.push('<w:p><w:pPr><w:spacing w:after="160"/></w:pPr></w:p>');
    });

    const docXml = '<?xml version="1.0" encoding="UTF-8" standalone="yes"?>' +
      '<w:document xmlns:w="http://schemas.openxmlformats.org/wordprocessingml/2006/main" ' +
      'xmlns:r="http://schemas.openxmlformats.org/officeDocument/2006/relationships" ' +
      'xmlns:wp="http://schemas.openxmlformats.org/drawingml/2006/wordprocessingDrawing" ' +
      'xmlns:a="http://schemas.openxmlformats.org/drawingml/2006/main" ' +
      'xmlns:pic="http://schemas.openxmlformats.org/drawingml/2006/picture"><w:body>' +
      body.join('') +
      '<w:sectPr><w:pgSz w:w="11906" w:h="16838"/><w:pgMar w:top="1152" w:right="1296" w:bottom="1152" w:left="1296" w:header="720" w:footer="720" w:gutter="0"/></w:sectPr>' +
      '</w:body></w:document>';

    const docRels = '<?xml version="1.0" encoding="UTF-8" standalone="yes"?>' +
      '<Relationships xmlns="http://schemas.openxmlformats.org/package/2006/relationships">' +
      rels.map((r) => '<Relationship Id="' + r.id + '" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/image" Target="' + r.target + '"/>').join('') +
      '</Relationships>';

    const contentTypes = '<?xml version="1.0" encoding="UTF-8" standalone="yes"?>' +
      '<Types xmlns="http://schemas.openxmlformats.org/package/2006/content-types">' +
      '<Default Extension="rels" ContentType="application/vnd.openxmlformats-package.relationships+xml"/>' +
      '<Default Extension="xml" ContentType="application/xml"/>' +
      '<Default Extension="png" ContentType="image/png"/>' +
      '<Default Extension="jpg" ContentType="image/jpeg"/>' +
      '<Default Extension="jpeg" ContentType="image/jpeg"/>' +
      '<Default Extension="gif" ContentType="image/gif"/>' +
      '<Default Extension="webp" ContentType="image/webp"/>' +
      '<Override PartName="/word/document.xml" ContentType="application/vnd.openxmlformats-officedocument.wordprocessingml.document.main+xml"/>' +
      '</Types>';

    const rootRels = '<?xml version="1.0" encoding="UTF-8" standalone="yes"?>' +
      '<Relationships xmlns="http://schemas.openxmlformats.org/package/2006/relationships">' +
      '<Relationship Id="rId1" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/officeDocument" Target="word/document.xml"/>' +
      '</Relationships>';

    const enc = new TextEncoder();
    const entries = [
      { name: '[Content_Types].xml', data: enc.encode(contentTypes) },
      { name: '_rels/.rels', data: enc.encode(rootRels) },
      { name: 'word/document.xml', data: enc.encode(docXml) },
      { name: 'word/_rels/document.xml.rels', data: enc.encode(docRels) },
    ];
    media.forEach((md) => entries.push({ name: md.name, data: md.data }));
    return zipStore(entries);
  }

  // ---------------- 导出流程 ----------------
  let panelWasOpen = false;
  function hideUI() {
    panelWasOpen = !!(PANEL && PANEL.style.display === 'block');
    if (PANEL) PANEL.style.display = 'none';
    if (FAB) FAB.style.display = 'none';
  }
  function showUI() {
    if (FAB) FAB.style.display = '';
    if (PANEL && panelWasOpen) PANEL.style.display = 'block';
  }

  async function runExport(kind) {
    if (TIP) TIP.textContent = '正在读取页面题目，请稍候…（长页面会自动滚动加载）';
    hideUI();
    await nap(60);
    let res;
    try { res = await extract(); }
    catch (e) { res = { ok: false, error: e && e.message ? e.message : String(e) }; }
    finally { showUI(); }
    if (!res || !res.ok) {
      if (TIP) TIP.textContent = (res && res.error) || '提取失败，请确认在作业/考试页。';
      return;
    }

    let ocrMsg = '';
    if (CFG.includeOcr) {
      const targets = collectOcrTargets(res);
      if (targets.length) {
        if (TIP) TIP.textContent = '正在识别图片文字 0/' + targets.length + '…（首次会下载 OCR 模型，请稍等）';
        const r = await runOcrOnImages(res, (done, total) => {
          if (TIP) TIP.textContent = '正在识别图片文字 ' + done + '/' + total + '…';
        });
        if (r.failed) ocrMsg = '（OCR 不可用，已全部用原图）';
        else ocrMsg = '（识别为文字 ' + r.ok + ' 张，其余 ' + r.skipped + ' 张用原图）';
      }
    }
    const m = meta(res);
    const base = safeName(m.name) || ('学习通' + m.kind);
    try {
      if (kind === 'docx') {
        const bytes = buildDocx(res);
        downloadBlob(base + '（' + m.kind + '）.docx',
          new Blob([bytes], { type: 'application/vnd.openxmlformats-officedocument.wordprocessingml.document' }));
      } else if (kind === 'md') {
        downloadText(base + '.md', buildMarkdown(res), 'text/markdown');
      } else if (kind === 'txt') {
        downloadText(base + '.txt', buildText(res), 'text/plain');
      } else if (kind === 'copy') {
        await navigator.clipboard.writeText(buildText(res));
      }
    } catch (e) {
      if (TIP) TIP.textContent = '导出出错：' + (e && e.message ? e.message : e);
      return;
    }
    if (TIP) TIP.textContent = '完成：共 ' + res.questions.length + ' 题' + (CFG.includeAnswer ? '（含答案）' : '（未含答案）') + ocrMsg;
  }

  // ---------------- 界面 ----------------
  function buildUI() {
    if (document.getElementById('xxt-fab')) return;
    const style = document.createElement('style');
    style.textContent = [
      '#xxt-fab{position:fixed;right:22px;bottom:96px;z-index:2147483000;background:#ff6b4a;color:#fff;',
      'border:none;border-radius:24px;padding:11px 18px;font:700 15px/1.2 "Microsoft YaHei",sans-serif;',
      'cursor:pointer;box-shadow:0 6px 18px rgba(0,0,0,.25);}',
      '#xxt-panel{position:fixed;right:22px;bottom:150px;z-index:2147483000;width:288px;background:#fff;',
      'color:#243;border-radius:14px;box-shadow:0 10px 40px rgba(0,0,0,.28);padding:16px;display:none;',
      'font:13px/1.5 "Microsoft YaHei",sans-serif;}',
      '#xxt-panel h3{margin:0 0 10px;font-size:15px;color:#1f2a44;}',
      '#xxt-panel label{display:flex;align-items:center;gap:6px;margin:7px 0;cursor:pointer;color:#334;}',
      '#xxt-panel .row{display:flex;gap:8px;flex-wrap:wrap;margin-top:10px;}',
      '#xxt-panel button{flex:1 1 46%;padding:9px 8px;border:1px solid #e2e6ee;border-radius:9px;',
      'background:#f7f9fc;cursor:pointer;font:13px "Microsoft YaHei",sans-serif;}',
      '#xxt-panel button:hover{background:#eef2f8;}',
      '#xxt-panel .primary{background:#24304a;color:#fff;border-color:#24304a;}',
      '#xxt-tip{color:#8a91a3;margin-top:10px;line-height:1.5;min-height:18px;}',
    ].join('');
    document.head.appendChild(style);

    FAB = document.createElement('button');
    FAB.id = 'xxt-fab';
    FAB.textContent = '导出题目';
    document.body.appendChild(FAB);

    PANEL = document.createElement('div');
    PANEL.id = 'xxt-panel';
    PANEL.innerHTML =
      '<h3>学习通一键导出 <span style="color:#8a91a3;font-weight:400">v1.0</span></h3>' +
      '<label><input type="checkbox" id="xxt-opt" ' + (CFG.includeOptions ? 'checked' : '') + '>包含选项</label>' +
      '<label><input type="checkbox" id="xxt-ans">包含答案（默认关）</label>' +
      '<label><input type="checkbox" id="xxt-img" ' + (CFG.includeImages ? 'checked' : '') + '>保留图片题</label>' +
      '<label><input type="checkbox" id="xxt-ocr" ' + (CFG.includeOcr ? 'checked' : '') + '>图片文字识别 OCR</label>' +
      '<div class="row">' +
      '<button class="primary" id="xxt-word">导出 Word (.docx)</button>' +
      '<button id="xxt-md">导出 Markdown</button>' +
      '<button id="xxt-txt">导出 TXT</button>' +
      '<button id="xxt-copy">复制文字</button>' +
      '</div>' +
      '<div id="xxt-tip"></div>';
    document.body.appendChild(PANEL);
    TIP = PANEL.querySelector('#xxt-tip');

    FAB.addEventListener('click', () => { PANEL.style.display = PANEL.style.display === 'block' ? 'none' : 'block'; });
    PANEL.querySelector('#xxt-opt').addEventListener('change', (e) => (CFG.includeOptions = e.target.checked));
    PANEL.querySelector('#xxt-ans').addEventListener('change', (e) => (CFG.includeAnswer = e.target.checked));
    PANEL.querySelector('#xxt-img').addEventListener('change', (e) => (CFG.includeImages = e.target.checked));
    PANEL.querySelector('#xxt-ocr').addEventListener('change', (e) => (CFG.includeOcr = e.target.checked));
    PANEL.querySelector('#xxt-word').addEventListener('click', () => runExport('docx'));
    PANEL.querySelector('#xxt-md').addEventListener('click', () => runExport('md'));
    PANEL.querySelector('#xxt-txt').addEventListener('click', () => runExport('txt'));
    PANEL.querySelector('#xxt-copy').addEventListener('click', () => runExport('copy'));
  }

  if (document.readyState === 'loading') {
    document.addEventListener('DOMContentLoaded', buildUI);
  } else {
    buildUI();
  }

})();