// ==UserScript==
// @name         学员中心 · 2倍速学习助手
// @namespace    local.icampus.study
// @version      1.1.1
// @description  2倍速顺序播放、测验自动作答、按逐题反馈记忆答案并重试。
// @match        https://icampus.yunyinsh.com/course/*
// @run-at       document-start
// @grant        none
// @sandbox      raw
// @noframes
// ==/UserScript==

(() => {
  'use strict';
  const normalize = text => String(text || '').normalize('NFKC').replace(/\s+/g, '').trim();
  function route(hash) {
    const [path, query = ''] = hash.replace(/^#/, '').split('?');
    return {list: path === '/my-course', id: path === '/my-course/learn' ? new URLSearchParams(query).get('id') : null};
  }
  function endpoint(raw, base) {
    try {
      const u = new URL(raw, base);
      if (u.origin !== new URL(base).origin) return null;
      const m = u.pathname.match(/^\/smtp\/api\/my-courses\/(packages|\d+)(?:\/(.*))?$/);
      return m ? {id: m[1], tail: m[2] || ''} : null;
    } catch { return null; }
  }
  function bodyJSON(body) {
    try { return typeof body === 'string' && body.length < 65536 ? JSON.parse(body) : null; } catch { return null; }
  }
  function courseDone(c) { return !!c && (c.status === 'COMPLETED' || !!c.completedAt); }
  function videoPlan(detail) {
    if (!detail?.course || !Array.isArray(detail.resources)) return {kind: 'wait'};
    const resources = [...detail.resources].sort((a, b) => a.sortNo - b.sortNo);
    const next = resources.find(r => r.completed !== true);
    if (next) return {kind: next.type === 'VIDEO' ? 'video' : 'manual', resource: next};
    if (detail.course.examRequired && detail.course.examPassed !== true) return {kind: 'quiz'};
    return {kind: 'finish'};
  }
  function resolveCards(cards, courses) {
    return cards.map(card => {
      const matches = courses.filter(c => normalize(c.courseName) === normalize(card.title));
      return {card, course: matches.length === 1 ? matches[0] : null};
    });
  }
  function leaseAvailable(lease, owner, now) { return !lease || lease.owner === owner || lease.until <= now; }
  function questionKey(q) {
    return JSON.stringify([q.type, normalize(q.title), normalize(q.group), q.options.map(o => normalize(o.text)).sort()]);
  }
  const selectionKey = texts => JSON.stringify(texts.map(normalize).sort());
  function chooseAnswer(q, entry) {
    const texts = q.options.map(o => normalize(o.text));
    if (!['single','multi'].includes(q.type) || !texts.length || texts.length > 8 || texts.some(t => !t) || new Set(texts).size !== texts.length) return null;
    if (entry?.correct?.every(t => texts.includes(t)) && entry.correct.length) return entry.correct;
    const ordered = [...texts].sort();
    const candidates = q.type === 'single' ? ordered.map(t => [t]) :
      Array.from({length: 2 ** ordered.length - 1}, (_, n) => ordered.filter((_, i) => ((n + 1) & (1 << i)) !== 0));
    return candidates.find(c => !(entry?.wrong || []).includes(selectionKey(c))) || null;
  }
  function learnCard(bank, snapshot, rows) {
    let learned = 0;
    for (const row of rows) {
      if (typeof row.correct !== 'boolean') continue;
      const q = snapshot.questions.find(q => q.id === String(row.questionId));
      if (!q) continue;
      const keys = q.type === 'multi' ? row.selectedOptionKeys : [row.selectedOptionKey];
      if (!Array.isArray(keys) || !keys.length || keys.some(k => typeof k !== 'string')) continue;
      const options = keys.map(k => q.options.find(o => o.key === k));
      if (options.some(o => !o)) continue;
      const texts = options.map(o => normalize(o.text));
      // Only learn feedback about exactly the submitted choice, never a stale answer card.
      if (selectionKey(texts) !== selectionKey(q.chosen)) continue;
      const key = questionKey(q), entry = bank[key] || {wrong: []};
      if (row.correct) entry.correct = texts;
      else {
        if (entry.correct && selectionKey(entry.correct) === selectionKey(texts)) delete entry.correct;
        entry.wrong = [...new Set([...(entry.wrong || []), selectionKey(texts)])];
      }
      bank[key] = entry; ++learned;
    }
    return learned;
  }
  function quizEndpoint(raw, base) {
    try {
      const u = new URL(raw, base); if (u.origin !== new URL(base).origin) return null;
      let m = u.pathname.match(/^\/smtp\/api\/my-courses\/(\d+)\/exam$/);
      if (m) return {kind:'exam', id:m[1]};
      m = u.pathname.match(/^\/smtp\/api\/my-courses\/exams\/(\d+)\/(answers|submit)$/);
      if (m) return {kind:m[2], examId:m[1]};
      m = u.pathname.match(/^\/smtp\/api\/my-courses\/exam-papers\/(\d+)\/answer-card$/);
      return m ? {kind:'card', paperId:m[1]} : null;
    } catch { return null; }
  }
  const core = {normalize, route, endpoint, bodyJSON, courseDone, videoPlan, resolveCards, leaseAvailable,
    questionKey, selectionKey, chooseAnswer, learnCard, quizEndpoint};
  if (typeof module === 'object' && module.exports && typeof window === 'undefined') { module.exports = core; return; }
  if (window.top !== window.self || document.getElementById('icampus-study-helper')) return;

  const LEASE_KEY = 'icampus.study.v1.lease';
  const BANK_KEY = 'icampus.study.v1.answers';
  const SNAPSHOT_KEY = 'icampus.study.v1.lastExam';
  const RESUME_KEY = 'icampus.study.v1.recovery';
  let mediaLoad = null;
  let recoveryUsed = new Set();
  let bank;
  let lastExam;
  try { bank = JSON.parse(localStorage.getItem(BANK_KEY) || '{}'); } catch { bank = {}; }
  if (!bank || typeof bank !== 'object' || Array.isArray(bank)) bank = {};
  try { lastExam = JSON.parse(localStorage.getItem(SNAPSHOT_KEY) || 'null'); } catch { lastExam = null; }
  if (!lastExam || !Array.isArray(lastExam.questions)) lastExam = null;
  const exams = new Map();
  let quiz = null;
  let autoQuiz;
  let quizOnly = false;
  const VERIFIED_ANSWERS = [{"question":"在“2.11”辽宁先达公司较大爆炸事故中，以下哪项是导致爆炸发生的直接原因？( )","answerText":"一操未对物料复核确认，二操错误地将丙酰三酮与氯代胺同时加入储罐内反应"},{"question":"关于“4.6”成都精济药业实验室电气火灾事故，以下哪项不是该事故的间接原因？( )","answerText":"实验室内电气线路短路，引燃周围可燃物"},{"question":"“6.13”浙江温岭液化石油气槽罐车重大爆炸事故的直接原因是？( )","answerText":"驾驶员在弯道路段未及时减速导致车辆侧翻，罐体与护栏碰撞破裂解体"},{"question":"根据对黎巴嫩贝鲁特港“8.4”特大爆炸事故的分析，以下哪项不是事故的间接原因？( )","answerText":"焊接维修作业产生的火花引燃了仓库中的烟花爆竹"},{"question":"“9.19”中科（广东）炼化公司闪爆事故的直接原因是？( )","answerText":"作业人员在切割法兰时，砂轮机产生的火花引燃了污水池内的环氧乙烷爆炸性气体"},{"question":"“4.22”上海金山胜瑞电子科技公司较大火灾事故的直接原因是？( )","answerText":"作业人员黄某在车间内违章吸烟，引燃周边杂物"},{"question":"在“5.29”上海石化公司爆燃事故中，以下哪项不是事故的间接原因？( )","answerText":"作业人员打开了轻石脑油进料界区阀门，造成物料从盲板法兰处泄漏"}];
  const owner = crypto.randomUUID();
  const details = new Map();
  let courses = [];
  let packagesAt = 0;
  let running = false;
  let busy = false;
  let runNumber = 0;
  let status = '就绪：刷新后，在课程列表或学习页点击开始。';
  let panel;
  let mode;
  let active = null;
  let routeSince = Date.now();
  let lastHash = location.hash;
  let navigatingUntil = 0;
  let courseNavigationPending = false;
  let resourceSwitch = null;
  let expectedCourse = null;
  let verifyAfterBack = null;
  let mustObservePackagesAfter = 0;
  let lastNetworkAt = 0;
  let startAt = 0;
  const logs = [];
  const visible = el => !!el && el.getClientRects().length > 0;
  const currentVideo = () => document.querySelector('video.player__video');
  function log(message) {
    logs.push({time: new Date().toLocaleTimeString(), message: String(message).replace(/https?:\/\/\S+/g, '[链接]').slice(0, 300)});
    if (logs.length > 60) logs.shift();
  }
  function show(message) { if (status !== message) { status = message; log(message); } render(); }
  function readLease() { try { return JSON.parse(localStorage.getItem(LEASE_KEY) || 'null'); } catch { return null; } }
  function holdLease() {
    if (!leaseAvailable(readLease(), owner, Date.now())) return false;
    try { localStorage.setItem(LEASE_KEY, JSON.stringify({owner, until: Date.now() + 12000})); }
    catch { return false; }
    return readLease()?.owner === owner;
  }
  function releaseLease() { try { if (readLease()?.owner === owner) localStorage.removeItem(LEASE_KEY); } catch {} }
  function stop(message = '已暂停；点击开始可继续。') {
    running = false; ++runNumber;
    const video = active?.video;
    active = null;
    mediaLoad = null;
    try { sessionStorage.removeItem(RESUME_KEY); } catch {}
    if (video && !video.paused) video.pause();
    releaseLease(); show(message);
  }
  function safeCourse(c) {
    if (!c || typeof c.id !== 'string') return null;
    return Object.fromEntries(['id', 'courseName', 'status', 'completedAt', 'examRequired', 'examPassed', 'examScorePercent', 'progressPercent'].map(k => [k, c[k]]));
  }
  function receive(meta, response, httpStatus) {
    if (!meta) return;
    if (meta.kind) return receiveQuiz(meta, response, httpStatus);
    const relevant = meta.id === route(location.hash).id || meta.id === 'packages';
    if (relevant && running && (httpStatus === 401 || httpStatus === 403)) return stop('登录状态失效或无权限，请重新登录后刷新。');
    if (!response || typeof response !== 'object' || response.bizCode === undefined) return;
    if (response.bizCode !== 0) {
      if (running && relevant) stop(`平台未接受操作（${response.bizCode}）：${response.message || '请查看页面提示'}`);
      return;
    }
    const data = response.data;
    if (meta.id === 'packages' && Array.isArray(data)) {
      courses = data.flatMap(p => Array.isArray(p.courses) ? p.courses : []).map(safeCourse).filter(Boolean);
      packagesAt = Date.now(); return;
    }
    if (!meta.tail && data?.course && Array.isArray(data.resources)) {
      const course = safeCourse(data.course);
      if (!course || course.id !== meta.id) return;
      details.set(meta.id, {course, at: Date.now(), resources: data.resources.map(r =>
        Object.fromEntries(['id','name','type','sortNo','completed','playable','currentPositionSeconds','durationSeconds'].map(k => [k, r[k]])))});
    }
    if (/^sessions\/[^/]+\/heartbeat$/.test(meta.tail) && data) {
      const resourceId = meta.body?.resourceId;
      const detail = details.get(meta.id);
      const resource = detail?.resources.find(r => r.id === resourceId);
      if (resource) {
        if (typeof data.resourceCompleted === 'boolean') resource.completed = data.resourceCompleted;
        if (typeof data.courseStatus === 'string') detail.course.status = data.courseStatus;
        if (typeof data.courseProgressPercent === 'number') detail.course.progressPercent = data.courseProgressPercent;
      }
      if (active && active.courseId === meta.id && active.id === resourceId) {
        lastNetworkAt = Date.now(); active.saved = true;
        active.serverPosition = data.currentPositionSeconds;
      }
    }
    render();
  }
  // 只旁观原网页的详情/心跳响应；不发送、重放或改写学习记录。
  function observe(raw, body) {
    const examMeta = quizEndpoint(raw, location.href);
    if (examMeta) return {...examMeta, body: bodyJSON(body)};
    const meta = endpoint(raw, location.href);
    if (!meta || (meta.tail && !/^sessions(?:\/[^/]+\/(heartbeat|end))?$/.test(meta.tail))) return null;
    return {...meta, body: bodyJSON(body)};
  }
  const originalFetch = window.fetch;
  if (originalFetch) window.fetch = function (...args) {
    const promise = Reflect.apply(originalFetch, this, args);
    let meta;
    try { meta = observe(typeof args[0] === 'string' || args[0] instanceof URL ? String(args[0]) : args[0]?.url, args[1]?.body); } catch {}
    if (meta) promise.then(async response => {
      if (Number(response.headers.get('content-length')) > 524288) return;
      const copy = response.clone();
      const reader = copy.body?.getReader();
      if (!reader) return;
      const decoder = new TextDecoder(); let text = ''; let size = 0;
      try {
        for (;;) {
          const chunk = await reader.read(); if (chunk.done) break;
          size += chunk.value.byteLength;
          if (size > 524288) { void reader.cancel().catch(() => {}); return; }
          text += decoder.decode(chunk.value, {stream: true});
        }
        text += decoder.decode(); receive(meta, JSON.parse(text), response.status);
      } catch { /* 旁观失败不影响原请求。 */ }
    }).catch(() => {});
    return promise;
  };
  const xhrMeta = new WeakMap();
  const originalOpen = XMLHttpRequest.prototype.open;
  const originalSend = XMLHttpRequest.prototype.send;
  XMLHttpRequest.prototype.open = function (...args) {
    const result = Reflect.apply(originalOpen, this, args);
    xhrMeta.set(this, {url: args[1]}); return result;
  };
  XMLHttpRequest.prototype.send = function (...args) {
    const meta = observe(xhrMeta.get(this)?.url, args[0]);
    if (meta) this.addEventListener('loadend', function () {
      try {
        if (this.responseType === 'json') receive(meta, this.response, this.status);
        else if ((!this.responseType || this.responseType === 'text') && this.responseText.length <= 524288)
          receive(meta, JSON.parse(this.responseText), this.status);
      } catch {}
    }, {once: true});
    return Reflect.apply(originalSend, this, args);
  };

  function persistQuiz() {
    // Keep a bounded local bank; never store access tokens, media URLs or account details.
    const entries = Object.entries(bank).slice(-2000);
    bank = Object.fromEntries(entries);
    try {
      localStorage.setItem(BANK_KEY, JSON.stringify(bank));
      if (lastExam) localStorage.setItem(SNAPSHOT_KEY, JSON.stringify(lastExam));
      return true;
    } catch { if (running) stop('答案记忆保存失败，请检查浏览器本地存储空间。'); return false; }
  }
  function savedAnswersMatch(snapshot, body) {
    if (!Array.isArray(body?.answers) || body.answers.length !== snapshot.questions.length) return false;
    return snapshot.questions.every(q => {
      const answer = body.answers.find(a => a.questionId === q.id);
      if (!answer) return false;
      const keys = q.type === 'multi' ? answer.selectedOptionKeys : [answer.selectedOptionKey];
      if (!Array.isArray(keys) || !keys.length) return false;
      const options = keys.map(k => q.options.find(o => o.key === k));
      return options.every(Boolean) && selectionKey(options.map(o => o.text)) === selectionKey(q.chosen);
    });
  }
  function receiveQuiz(meta, response, httpStatus) {
    const id = route(location.hash).id;
    const relevant = meta.kind === 'exam' ? meta.id === id :
      meta.kind === 'card' ? lastExam?.courseId === id && lastExam.paperId === meta.paperId :
      exams.get(id)?.examId === meta.examId;
    if (!relevant) return;
    if (httpStatus === 401 || httpStatus === 403 || (response?.bizCode !== undefined && response.bizCode !== 0)) {
      if (running) stop(`测验操作失败：${response?.message || '登录状态或权限异常'}`); return;
    }
    if (response?.bizCode !== 0) return;
    const data = response.data;
    if (meta.kind === 'exam' && data && typeof data.examId === 'string') {
      exams.set(id, {examId:data.examId, paperId:String(data.paperId || data.assessmentPaperId || data.examId),
        status:data.status, maxAttempts:data.maxAttempts, remainingAttempts:data.remainingAttempts,
        canRetry:data.canRetry, attemptsExhausted:data.attemptsExhausted,
        questionIds:Array.isArray(data.questions) ? data.questions.map(q => String(q.questionId)) : [], at:Date.now()});
    } else if (meta.kind === 'card' && Array.isArray(data) && lastExam?.submitted === true) {
      const count = learnCard(bank, lastExam, data);
      if (count) { persistQuiz(); log(`已根据平台逐题反馈更新 ${count} 道题的答案记忆。`); }
    } else if (meta.kind === 'answers' && lastExam?.examId === meta.examId && savedAnswersMatch(lastExam, meta.body)) {
      lastExam.answersSaved = true; persistQuiz(); finishQuizSubmission(id);
    } else if (meta.kind === 'submit' && lastExam?.examId === meta.examId && data) {
      lastExam.grade = Object.fromEntries(['scorePercent','passed','canRetry','attemptsExhausted','remainingAttempts'].map(k => [k,data[k]]));
      finishQuizSubmission(id);
    }
  }
  function finishQuizSubmission(id) {
    if (lastExam?.courseId === id && lastExam.answersSaved && lastExam.grade && !lastExam.submitted) {
      const data = lastExam.grade;
      lastExam.submitted = true;
      if (Number(data.scorePercent) === 100) {
        for (const q of lastExam.questions) bank[questionKey(q)] = {correct:q.chosen.map(normalize), wrong:[]};
        log('本次100%正确，已保存整卷答案。');
      }
      const exam = exams.get(id); if (exam) Object.assign(exam, {status:'SUBMITTED', canRetry:data.canRetry,
        attemptsExhausted:data.attemptsExhausted, remainingAttempts:data.remainingAttempts});
      const course = details.get(id)?.course;
      if (course && typeof data.passed === 'boolean') { course.examPassed=data.passed; course.examScorePercent=data.scorePercent; }
      persistQuiz();
      if (quiz?.courseId === id) { quiz.phase='result'; quiz.since=Date.now(); }
    }
  }
  function quizButton(root, text) {
    return [...root.querySelectorAll('button')].find(b => visible(b) && normalize(b.textContent) === text && !b.disabled);
  }
  function readQuestions(root) {
    const nodes = [...root.querySelectorAll('article.quiz-question')];
    return nodes.map(node => {
      const options = [...node.querySelectorAll('button.quiz-option')].map(button => ({
        key:button.querySelector('.quiz-option__key')?.textContent.trim(),
        text:button.querySelector('.quiz-option__text')?.textContent.trim(),
        selected:button.classList.contains('is-selected'), button}));
      return {id:node.getAttribute('data-qid'), title:node.querySelector('.quiz-question__title')?.textContent,
        group:'', type:node.querySelector('.quiz-options--multi') ? 'multi' : options.length ? 'single' : 'unsupported',
        unsupported:!!node.querySelector('img, input, textarea') || !!root.querySelector('.quiz-material'), options};
    });
  }
  function pureQuestion(q, chosen) {
    return {id:q.id,title:q.title,type:q.type,group:q.group,
      options:q.options.map(o => ({key:o.key,text:o.text})),chosen};
  }
  function quizWait(message, timeout = 25000) {
    show(message);
    if (Date.now() - quiz.since > timeout) stop('测验页面未在预期时间内响应。已保留答案记忆，请检查网页后继续。');
  }
  function tickQuiz(id) {
    if (autoQuiz && !autoQuiz.checked && !quizOnly) return stop('自动测验已关闭，请开启后继续。');
    if (!quiz || quiz.courseId !== id) quiz = {courseId:id,phase:'idle',since:Date.now(),round:0};
    const root = document.querySelector('.course-quiz');
    if (!root) return quizWait('等待课程测验区域加载…');
    const result = root.querySelector('.quiz-result');
    if (result && visible(result)) {
      // A previously passed course has no retake button; do not resubmit it.
      if (result.querySelector('.quiz-result__status.is-pass')) {
        const course = details.get(id)?.course;
        if (course) course.examPassed = true;
        const percent = result.querySelector('.quiz-result__score strong')?.textContent.trim();
        log(`测验已合格（${percent || '平台确认'}）。`);
        if (quizOnly) return stop(`测验已合格（${percent || '平台确认'}），答案已按可用反馈保存。`);
        quiz = null; return;
      }
      if (quiz.phase === 'opening' || quiz.phase === 'retrying') return quizWait('正在打开测验…');
      const exam = exams.get(id);
      if (exam?.canRetry === false || exam?.attemptsExhausted || root.querySelector('.quiz-result__exhausted'))
        return stop('平台答题次数已用完，已保留答案记忆。');
      const retry = quizButton(root, '重新测验');
      if (!retry) return stop('本次未合格，但页面没有可用的重新测验按钮。');
      if (++quiz.round > 256) return stop('本轮重试达到256次，已暂停，请检查是否存在无法判断的题目。');
      quiz.phase='retrying'; quiz.since=Date.now(); quiz.plan=null;
      retry.click(); show('未合格，读取上次逐题反馈后重新作答…'); return;
    }
    if (quiz.phase === 'confirming') {
      const dialogs = [...document.querySelectorAll('.van-dialog')].filter(visible);
      const dialog = dialogs.find(d => normalize(d.querySelector('.van-dialog__header')?.textContent) === '确认交卷');
      if (dialog) {
        const confirm = quizButton(dialog, '确定交卷');
        if (confirm) { quiz.phase='submitting'; quiz.since=Date.now(); confirm.click(); show('已确认交卷，等待平台评分…'); return; }
      }
      return quizWait('等待交卷确认框…');
    }
    if (quiz.phase === 'submitting' || quiz.phase === 'result') return quizWait('等待平台返回测验结果…', 45000);
    const questions = readQuestions(root);
    if (!questions.length) {
      if (quiz.phase === 'opening' || quiz.phase === 'retrying') return quizWait('正在加载试卷…');
      const start = quizButton(root, '开始测验');
      if (!start) return quizWait('等待可用的测验入口…');
      quiz.phase='opening'; quiz.since=Date.now(); start.click(); show('正在开始本门测验…'); return;
    }
    const exam = exams.get(id);
    if (!exam || exam.status === 'SUBMITTED' || questions.length !== exam.questionIds.length ||
      questions.some(q => !exam.questionIds.includes(q.id))) return quizWait('核对当前试卷数据…');
    if (quiz.lastClick) {
      const pending=quiz.lastClick;
      const option=questions.find(q=>q.id===pending.id)?.options.find(o=>o.key===pending.key);
      if (option?.selected===pending.want) quiz.lastClick=null;
      else {
        if(Date.now()-pending.at>8000) stop('选项点击后没有生效，已暂停，请检查页面。');
        return;
      }
    }
    if (!quiz.plan) {
      const planned = [];
      for (const q of questions) {
        if (q.unsupported || !q.title || !q.id || q.options.some(o => !o.key))
          return stop('本卷包含图片、材料题、填空或问答题，需要手动作答；已保留其他答案记忆。');
        const key = questionKey(q);
        const seed = VERIFIED_ANSWERS.find(a => normalize(a.question) === normalize(q.title));
        if (!bank[key] && seed && q.type === 'single' && q.options.some(o => normalize(o.text) === normalize(seed.answerText)))
          bank[key] = {correct:[normalize(seed.answerText)],wrong:[]};
        const choice = chooseAnswer(q, bank[key]);
        if (!choice) return stop('某题的可用选项已全部尝试，或选项无法唯一识别，请人工核对。');
        planned.push(pureQuestion(q, choice));
      }
      const signature = qs => JSON.stringify(qs.map(q => [questionKey(q),selectionKey(q.chosen)]).sort());
      if (lastExam?.courseId === id && lastExam.submitted && signature(lastExam.questions) === signature(planned))
        return stop('未取得能改变答案的逐题反馈，已暂停，避免反复提交同一份答案。');
      quiz.plan = planned; quiz.phase='answering'; quiz.since=Date.now();
      show(`自动作答：共 ${questions.length} 题，优先使用已确认答案。`);
    }
    for (const planned of quiz.plan) {
      const q = questions.find(q => q.id === planned.id);
      if (!q || questionKey(q) !== questionKey(planned)) return stop('作答过程中题目发生变化，已暂停。');
      for (const option of q.options) {
        const want = planned.chosen.includes(normalize(option.text));
        if (q.type === 'single' ? want && !option.selected : want !== option.selected) {
          quiz.lastClick={id:q.id,key:option.key,want,at:Date.now()};
          option.button.click(); quiz.since=Date.now(); return;
        }
      }
      if (selectionKey(q.options.filter(o => o.selected).map(o => o.text)) !== selectionKey(planned.chosen))
        return stop('页面选项状态与计划不一致，已暂停。');
    }
    const submit = root.querySelector('button.quiz-footer__submit');
    if (!visible(submit) || submit.disabled) return quizWait('等待交卷按钮可用…');
    lastExam = {courseId:id,examId:exam.examId,paperId:exam.paperId,questions:quiz.plan,
      answersSaved:false,submitted:false};
    if (!persistQuiz()) return;
    quiz.phase='confirming'; quiz.since=Date.now(); submit.click(); show('作答完成，正在交卷…');
  }

  function goBack(forVerification) {
    const back = document.querySelector('.van-nav-bar__left');
    if (!back) return stop('找不到返回列表按钮，请手动返回课程列表后继续。');
    if (forVerification) verifyAfterBack = route(location.hash).id;
    mustObservePackagesAfter = Date.now();
    navigatingUntil = Date.now() + 20000;
    courseNavigationPending = true;
    active = null;
    back.click();
    show('正在返回列表，等待平台核对课程状态…');
  }
  function tickList() {
    if (!packagesAt || packagesAt < mustObservePackagesAfter) {
      if (Date.now() - routeSince > 25000) stop('未收到新的课程列表数据，请刷新页面后开始。');
      return;
    }
    if (verifyAfterBack) {
      const previous = courses.find(c => c.id === verifyAfterBack);
      if (!courseDone(previous)) return stop('视频已播完，但平台尚未确认整门课程完成。请查看课程状态后继续。');
      log('平台已确认上一门课程完成。'); verifyAfterBack = null;
    }
    const cards = [...document.querySelectorAll('article.course-row')].filter(visible)
      .map(el => ({el, title: el.querySelector('.course-row__title')?.textContent}));
    if (!cards.length) {
      if (Date.now() - routeSince > 25000) stop('没有找到课程列表，请检查是否已登录。');
      return;
    }
    const mapped = resolveCards(cards, courses);
    if (mapped.some(x => !x.course)) return stop('课程名称重复或列表结构发生变化，请进入具体课程后选择“仅当前课程”。');
    const next = mapped.find(x => !courseDone(x.course));
    if (!next) return stop('当前显示的课程均已由平台确认完成。');
    expectedCourse = next.course.id;
    details.delete(expectedCourse);
    navigatingUntil = Date.now() + 20000;
    courseNavigationPending = true;
    next.card.el.click();
    show(`正在打开：${next.course.courseName}`);
  }
  function recoverMedia(id, resourceId, reason) {
    const key = `${id}/${resourceId}`;
    if (recoveryUsed.has(key)) return stop(`${reason}，自动恢复一次后仍失败，请检查网络并手动刷新。`);
    recoveryUsed.add(key);
    try {
      sessionStorage.setItem(RESUME_KEY, JSON.stringify({hash:location.hash, expires:Date.now()+120000,
        mode:mode.value, autoQuiz:autoQuiz?.checked !== false, used:[...recoveryUsed]}));
    } catch { return stop(`${reason}，无法保存恢复状态，请手动刷新后继续。`); }
    // The website tears down its old session and fetches fresh media on reload.
    // Only this explicit recovery reload resumes; ordinary refreshes stay paused.
    running=false; ++runNumber;
    const v=active?.video; active=null; mediaLoad=null;
    if(v && !v.paused) v.pause();
    releaseLease(); show(`${reason}，正在刷新恢复（本视频最多一次）…`);
    location.reload();
  }
  function waitMedia(id, resource, video) {
    const key=`${id}/${resource.id}`;
    if(!mediaLoad || mediaLoad.key!==key) mediaLoad={key,since:Date.now(),overlayTried:false,video:null,src:null,settledAt:0};
    const load=mediaLoad;
    if(video?.error) { recoverMedia(id,resource.id,'视频加载错误'); return false; }
    const staleSource=resourceSwitch?.id===resource.id && video===resourceSwitch.previousVideo && video?.currentSrc===resourceSwitch.previousSrc;
    if(!video || video.readyState<2 || !video.currentSrc || video.seeking || staleSource) {
      load.settledAt=0;
      const elapsed=Date.now()-load.since;
      const overlay=document.querySelector('.player__play-overlay');
      if(!load.overlayTried && elapsed>=10000 && visible(overlay)) {
        load.overlayTried=true; overlay.click();
      }
      show(`正在加载：${resource.name}（${Math.floor(elapsed/1000)}秒）`);
      if(elapsed>=90000) recoverMedia(id,resource.id,'视频加载超过90秒');
      return false;
    }
    if(load.video!==video || load.src!==video.currentSrc || !load.settledAt) {
      load.video=video; load.src=video.currentSrc; load.settledAt=Date.now(); return false;
    }
    // Let the website finish restoring the position and its own initial rate.
    return Date.now()-load.settledAt>=1000;
  }
  async function tickCourse(id) {
    if (expectedCourse && expectedCourse !== id) return stop('打开的课程与选定课程不一致，已暂停。');
    expectedCourse = null;
    const detail = details.get(id);
    if (!detail) {
      if (Date.now() - routeSince > 20000) stop('未捕获课程详情。安装后请刷新学习页，再点击开始。');
      return;
    }
    const plan = videoPlan(detail);
    // 正在播放的资源自然结束后再切换，即便平台提前返回 completed。
    if (active && active.courseId === id && !active.video.ended) return monitor();
    if (active?.video.ended) {
      const resource = detail.resources.find(r => r.id === active.id);
      active.endedAt ||= Date.now();
      if (resource?.completed !== true) {
        show('视频已结束，等待平台确认保存…');
        if (Date.now() - active.endedAt > 25000) stop('平台尚未确认视频完成，请返回列表核对后再继续。');
        return;
      }
      log('平台已确认本段视频完成。'); active = null;
    }
    if (plan.kind === 'manual') return stop('下一项不是视频，请在页面中完成该学习资源后继续。');
    if (plan.kind === 'quiz' || quiz?.courseId === id) return tickQuiz(id);
    if (plan.kind === 'finish') {
      if (mode.value === 'current') return stop('本门视频及测验条件已满足；请返回列表核对最终完成状态。');
      return goBack(true);
    }
    if (plan.kind !== 'video') return;
    const resource = plan.resource;
    const buttons = [...document.querySelectorAll('button.resource-item')];
    const matches = buttons.filter(b => normalize(b.querySelector('.resource-item__title')?.textContent) === normalize(resource.name));
    if (matches.length !== 1) return stop('未能唯一识别下一段视频，请手动选择后检查页面。');
    const button = matches[0];
    if (!button.classList.contains('is-active')) {
      if (button.disabled || resource.playable === false) return stop('下一段视频尚未解锁，请按平台提示完成前置学习。');
      if (resourceSwitch?.id === resource.id) {
        if (Date.now() - resourceSwitch.at > 20000) stop('切换视频没有成功，请手动选择该视频后继续。');
        return;
      }
      resourceSwitch = {id: resource.id, at: Date.now(),previousVideo:currentVideo(),previousSrc:currentVideo()?.currentSrc};
      mediaLoad = null;
      navigatingUntil = Date.now() + 5000;
      button.click(); show(`正在加载：${resource.name}`); routeSince = Date.now(); return;
    }
    const video = currentVideo();
    if (!waitMedia(id, resource, video)) return;
    resourceSwitch = null;
    // 设置一次，平台如改变速率就停止，避免与播放器循环争抢。
    const run = runNumber;
    active = {video, id: resource.id, courseId: id, src: video.currentSrc,
      lastPosition: video.currentTime, progressedAt: Date.now(), started: Date.now(), saved: false, serverPosition: null,
      phase:'starting', attempts:0, playPending:false, nextPlayAt:0};
    mediaLoad=null;
    lastNetworkAt = Date.now();
    video.playbackRate = 2;
    if (Math.abs(video.playbackRate - 2) > 0.01) return stop('播放器未接受2倍速，请检查页面倍速设置。');
    attemptPlay(active,run);
    if(running) show(`正在启动2倍速播放：${resource.name}`);
  }
  function attemptPlay(a, run=runNumber) {
    if(!running || active!==a || a.playPending || a.attempts>=3 || Date.now()<a.nextPlayAt) return;
    a.playPending=true; ++a.attempts; a.nextPlayAt=Date.now()+2000;
    const failed=error => {
      if(!running || run!==runNumber || active!==a) return;
      a.playPending=false;
      if(error?.name==='NotAllowedError') return stop('浏览器阻止自动播放，请手动点击网页“点击播放”，然后点助手继续。');
      if(error?.name!=='AbortError') recoverMedia(a.courseId,a.id,'播放启动失败');
      // AbortError commonly means the website is replacing the media source.
    };
    try { Promise.resolve(a.video.play()).then(() => {
      if(!running || run!==runNumber || active!==a) return;
      a.playPending=false;
    },failed); } catch(error) { failed(error); }
  }
  function monitor() {
    const a = active, v = a.video;
    const resource=details.get(a.courseId)?.resources.find(r=>r.id===a.id);
    const selected=document.querySelector('button.resource-item.is-active .resource-item__title');
    if(selected && normalize(selected.textContent)!==normalize(resource?.name)) return stop('视频已被手动切换，点击开始可继续。');
    if (!v.isConnected || currentVideo() !== v || v.currentSrc !== a.src) {
      active=null; mediaLoad=null; show('播放器正在重建，等待新视频就绪…'); return;
    }
    if (v.error) return recoverMedia(a.courseId,a.id,'视频播放错误');
    if(a.phase==='starting') {
      if(!v.paused && v.currentTime>a.lastPosition+0.1) { a.phase='playing'; show('2倍速播放中，正在核对平台保存进度。'); }
      else {
        if(Date.now()-a.started>20000) return recoverMedia(a.courseId,a.id,'视频未能开始播放');
        if(v.paused && v.readyState>=2) attemptPlay(a);
        return;
      }
    }
    if (Math.abs(v.playbackRate - 2) > 0.01) return stop('播放器改变了倍速，已暂停；请检查是否仍有诊断脚本在运行。');
    if (v.paused && !v.ended) return stop('视频已暂停；点击助手开始可继续。');
    if (v.currentTime > a.lastPosition + 0.1) { a.progressedAt = Date.now(); a.lastPosition = v.currentTime; }
    if (Date.now() - a.progressedAt > 60000) return recoverMedia(a.courseId,a.id,'视频超过60秒没有推进');
    if (Date.now() - lastNetworkAt > 75000) return stop('超过75秒未收到平台保存确认，已暂停，避免继续播放却未计入进度。');
  }
  async function tick() {
    if (!running || busy) return;
    busy = true;
    try {
      if (!holdLease()) return stop('另一个学习页正在使用助手，或浏览器禁止本地存储。');
      if (Date.now() - startAt < 600) return;
      if (location.hash !== lastHash) {
        const expected = navigatingUntil > Date.now();
        lastHash = location.hash; routeSince = Date.now(); active = null; navigatingUntil = 0;
        courseNavigationPending = false; resourceSwitch = null;
        if (!expected) return stop('页面已被手动切换；点击开始可继续。');
      }
      if (navigatingUntil > Date.now()) return;
      if (courseNavigationPending) return stop('课程页面跳转没有成功，请手动打开课程后继续。');
      const here = route(location.hash);
      if (here.list) tickList();
      else if (here.id) { if (quizOnly) tickQuiz(here.id); else await tickCourse(here.id); }
      else stop('请打开“我的课程”列表或课程学习页。');
      render();
    } catch { stop('页面结构或播放操作出现异常，请刷新页面后重试。'); }
    finally { busy = false; }
  }
  function render() {
    if (!panel) return;
    panel.querySelector('[data-status]').textContent = status;
    const v = active?.video;
    const course = details.get(route(location.hash).id)?.course;
    panel.querySelector('[data-progress]').textContent = v
      ? `实际 ${v.playbackRate.toFixed(1)}倍 · ${Math.floor(v.currentTime / 60)}:${String(Math.floor(v.currentTime % 60)).padStart(2, '0')} / ${Math.floor(v.duration / 60)}:${String(Math.floor(v.duration % 60)).padStart(2, '0')}\n平台进度 ${course?.progressPercent ?? '待确认'}% · ${active.saved ? '已收到保存确认' : '等待保存确认'}`
      : '以平台保存结果为准；电脑需保持唤醒。';
    panel.querySelector('[data-start]').disabled = running;
    panel.querySelector('[data-quiz-only]').disabled = running;
    mode.disabled = running;
  }
  function mount() {
    if (!document.body) return;
    const host = document.createElement('div'); host.id = 'icampus-study-helper';
    host.style.cssText = 'position:fixed;left:16px;bottom:16px;z-index:2147483646';
    panel = host.attachShadow({mode: 'open'});
    panel.innerHTML = `<style>:host{font:14px/1.6 system-ui;color:#eaf0fa}section{width:290px;background:#17243a;border:1px solid #6883a6;border-radius:12px;padding:15px;box-shadow:0 5px 24px #0005}strong{font-size:16px}p{margin:9px 0;white-space:pre-line}small{color:#b7c7df}button,select{font:inherit;border-radius:6px;border:1px solid #7186a5;padding:5px 9px;margin:3px 5px 3px 0}button{cursor:pointer;background:#dbeaff;color:#123}button:disabled{opacity:.5;cursor:default}select{width:100%;background:#fff;color:#123}[data-status]{min-height:45px}details{margin-top:8px}pre{white-space:pre-wrap;max-height:160px;overflow:auto;font-size:12px}</style>
      <section><strong>2倍速学习助手 · 1.1.1</strong><p data-status></p><small data-progress></small>
      <select aria-label="播放范围"><option value="all">按列表顺序继续课程</option><option value="current">仅当前课程</option></select>
      <div><button data-start>开始 / 继续</button><button data-stop>暂停</button></div>
      <label><input type="checkbox" data-quiz checked> 视频完成后自动做测验</label>
      <div><button data-quiz-only>只做本门测验</button></div>
      <small>错题根据平台反馈重试；合格后平台可能不允许重考。</small>
      <details><summary>运行记录</summary><pre></pre><button data-copy>更新记录</button></details></section>`;
    mode = panel.querySelector('select');
    autoQuiz = panel.querySelector('[data-quiz]');
    function beginRun(only, resume) {
      if (only && !route(location.hash).id) return show('请先进入需要作答的课程学习页。');
      if (!holdLease()) return show('另一个学习页正在运行助手，或本地存储不可用。请先暂停另一个页面。');
      if (only) currentVideo()?.pause();
      quizOnly=only; quiz=null;
      mediaLoad=null; recoveryUsed=new Set(resume?.used || []);
      running = true; ++runNumber; active = null; expectedCourse = null; verifyAfterBack = null;
      startAt = routeSince = Date.now(); lastHash = location.hash; navigatingUntil = 0;
      courseNavigationPending = false; resourceSwitch = null;
      show('已开始，正在核对课程与平台数据…'); void tick();
    }
    panel.querySelector('[data-start]').onclick = () => beginRun(false);
    panel.querySelector('[data-quiz-only]').onclick = () => beginRun(true);
    panel.querySelector('[data-stop]').onclick = () => stop();
    panel.querySelector('[data-copy]').onclick = () => { panel.querySelector('pre').textContent = logs.map(x => `${x.time} ${x.message}`).join('\n'); };
    document.body.append(host); render();
    try {
      const resume=JSON.parse(sessionStorage.getItem(RESUME_KEY) || 'null');
      sessionStorage.removeItem(RESUME_KEY);
      if(resume?.hash===location.hash && resume.expires>Date.now() && Array.isArray(resume.used) && resume.used.length<=100) {
        mode.value=resume.mode==='current'?'current':'all'; autoQuiz.checked=resume.autoQuiz!==false;
        beginRun(false,resume);
      }
    } catch { /* Ordinary reload or invalid checkpoint: wait for the user. */ }
  }
  window.addEventListener('storage', e => { if (e.key === LEASE_KEY && running && readLease()?.owner !== owner) stop('其他学习页接管了助手，本页已暂停。'); });
  window.addEventListener('pagehide', () => { running = false; releaseLease(); });
  if (document.body) mount(); else document.addEventListener('DOMContentLoaded', mount, {once: true});
  setInterval(() => { void tick(); }, 1000);
})();