(function () {
  'use strict';

  // 源代码：构建后连同 question-bank-core.js 一起装入单个油猴脚本。
  if (window.YianQuestionBankExporter) return;
  const core = window.QuestionBankCore;
  if (!core) throw new Error('题库提取核心未加载');
  const config = { autoExport: true, format: 'csv', settleMs: 1800 };
  const completed = new Set();
  let state = null;
  let panel = null;
  let statusNode = null;
  let debounceTimer = null;
  let previousPractice = false;
  let previousRoot = null;
  let previousSignature = '';

  function routeInfo() {
    const url = new URL(location.href);
    let params = url.searchParams;
    let path = url.pathname;
    if (url.hash.startsWith('#/')) {
      const hashUrl = new URL(url.hash.slice(1), url.origin);
      params = hashUrl.searchParams;
      path = hashUrl.pathname;
    }
    const root = document.querySelector('app-examtest, .pc_examtest');
    const local = url.protocol === 'file:';
    const practice = !!root && (local
      ? /[?&]flag=exercise(?:&|$)/.test(core.savedSourceURL(document))
      : params.get('flag') === 'exercise' && /\/exam\/[^/]+\/questions\/?$/.test(path));
    return { practice, root, title: params.get('title') || '', key: path + '|' + (params.get('title') || ''), local };
  }

  function fingerprint(bank) {
    return JSON.stringify([bank.title, bank.expectedTotal, bank.questions.map(q =>
      [q.number, q.type, q.question, q.options, q.answer, q.explanation, q.images])]);
  }

  function setStatus(message) {
    if (statusNode && statusNode.textContent !== message) statusNode.textContent = message;
  }

  function createPanel() {
    if (panel) return;
    panel = document.createElement('div');
    panel.id = 'yian-question-bank-exporter';
    panel.style.cssText = 'position:fixed;right:16px;bottom:16px;z-index:2147483600;max-width:min(330px,calc(100vw - 32px));padding:14px;border:1px solid #d5dde5;border-radius:12px;background:#fff;color:#233447;box-shadow:0 4px 20px #0002;font:13px/1.6 system-ui,sans-serif;text-align:left';
    const heading = document.createElement('strong');
    heading.textContent = '练习题库导出';
    statusNode = document.createElement('div');
    statusNode.setAttribute('role', 'status');
    statusNode.style.cssText = 'margin:6px 0;white-space:pre-line';
    const actions = document.createElement('div');
    actions.style.cssText = 'display:flex;gap:6px;flex-wrap:wrap';
    for (const format of ['csv', 'json', 'txt']) {
      const button = document.createElement('button');
      button.type = 'button';
      button.textContent = '导出 ' + format.toUpperCase();
      button.style.cssText = 'cursor:pointer;border:1px solid #d5dde5;border-radius:6px;background:#f5f8fa;padding:5px 9px;color:#233447;font:inherit';
      button.addEventListener('click', () => {
        try { exportCurrent(format); }
        catch (error) { setStatus('导出失败：' + error.message); }
      });
      actions.append(button);
    }
    const label = document.createElement('label');
    label.style.cssText = 'display:flex;gap:6px;align-items:center;margin-top:8px;cursor:pointer';
    const checkbox = document.createElement('input');
    checkbox.type = 'checkbox';
    checkbox.checked = config.autoExport;
    checkbox.addEventListener('change', () => {
      config.autoExport = checkbox.checked;
      tick();
    });
    label.append(checkbox, document.createTextNode('进入练习后自动导出 CSV'));
    panel.append(heading, statusNode, actions, label);
    document.body.append(panel);
  }

  function exportCurrent(format = config.format) {
    if (!routeInfo().practice) throw new Error('请先进入练习页面');
    const bank = core.extract(document, location.href);
    if (!bank.total) throw new Error('页面还没有题目，请稍后重试');
    // 手动导出可保存不完整内容，文件及提示都会标记缺失。
    core.download(bank, format);
    setStatus((bank.complete ? '已发起下载：' : '已发起不完整题库下载：') + bank.title + '\n'
      + bank.total + ' 题，' + bank.answered + ' 个答案'
      + (bank.complete ? '。' : '，请检查缺失内容。')
      + '\n若未出现文件，请点击上方导出按钮。');
    return bank;
  }

  function tick() {
    const route = routeInfo();
    if (!route.practice) {
      if (panel) panel.remove();
      panel = statusNode = null;
      state = null;
      previousPractice = false;
      previousRoot = route.root;
      return;
    }
    createPanel();
    const bank = core.extract(document, location.href);
    const signature = fingerprint(bank);
    const now = Date.now();
    if (!state || state.key !== route.key) {
      // SPA 改 URL 后旧题目可能仍留在 DOM，等待题目或组件更新。
      const transitioning = !!previousRoot && !!(previousPractice || previousSignature)
        && previousRoot === route.root && previousSignature === signature;
      state = { key: route.key, signature, since: now, initialRoot: route.root,
        initialSignature: signature, waitingForReplacement: transitioning };
    }
    if (state.waitingForReplacement && (route.root !== state.initialRoot || signature !== state.initialSignature)) {
      state.waitingForReplacement = false;
      state.since = now;
    }
    previousPractice = true;
    previousRoot = route.root;
    previousSignature = signature;
    if (state.signature !== signature) {
      state.signature = signature;
      state.since = now;
    }
    if (state.waitingForReplacement || (route.title && route.title.trim() !== bank.title.trim())) {
      setStatus('等待本次练习的题目加载…');
      return;
    }
    if (!bank.total || now - state.since < config.settleMs) {
      setStatus('正在读取题目与隐藏答案…');
      return;
    }
    if (bank.expectedTotal !== null && bank.expectedTotal !== bank.total) {
      setStatus('已读取 ' + bank.total + ' / ' + bank.expectedTotal + ' 题，等待全部加载。\n若页面分页，请逐页导出；手动导出会标记不完整。');
      return;
    }
    if (!bank.complete) {
      setStatus('已读取 ' + bank.total + ' 题，缺少 ' + bank.missingAnswers.length + ' 个答案。\n自动导出等待答案加载；可手动保存现有内容。');
      return;
    }
    const exportKey = state.key + '|' + signature;
    if (completed.has(exportKey)) return;
    if (!config.autoExport) {
      setStatus(bank.title + '\n' + bank.total + ' 题，答案齐全，可点击导出。');
      return;
    }
    try {
      exportCurrent(config.format);
      completed.add(exportKey);
    } catch (error) {
      config.autoExport = false;
      const checkbox = panel.querySelector('input');
      if (checkbox) checkbox.checked = false;
      setStatus('自动下载失败：' + error.message + '\n请点击导出按钮重试。');
      console.error('[谊安学题库导出]', error);
    }
  }

  const observer = new MutationObserver(records => {
    if (records.every(record => panel && (record.target === panel || panel.contains(record.target)))) return;
    clearTimeout(debounceTimer);
    debounceTimer = setTimeout(tick, 300);
  });
  observer.observe(document.body, { childList: true, subtree: true, characterData: true });
  const timer = setInterval(tick, 750); // 同时覆盖 Angular 路由和返回/前进。
  window.YianQuestionBankExporter = Object.freeze({
    exportCurrent,
    collectCurrent: () => core.extract(document, location.href),
    stop: () => { observer.disconnect(); clearInterval(timer); clearTimeout(debounceTimer); if (panel) panel.remove(); }
  });
  tick();
})();