/* Exact answer matching and role-scoped local search. */
(function (root) {
  'use strict';
  const ROLES = ['主操', '班长', '副操'];
  const cache = new WeakMap();

  function normalize(value) {
    // Strict answer identity: MPa/mPa, m²/m2 and Ⅰ/I are distinct.
    return String(value == null ? '' : value)
      .replace(/[\u200b-\u200d\u2060\uFEFF]/g, '')
      .replace(/\s+/g, ' ').trim();
  }

  // Search is intentionally more tolerant; these keys never authorize clicks.
  function searchNormalize(value) {
    return normalize(value).normalize('NFKC').replace(/[−﹣]/g, '-').toLowerCase();
  }

  function courseNormalize(value) { return searchNormalize(value); }

  function normalizeType(value) {
    const type = String(value || '').trim().replace(/^[\[【]|[\]】]$/g, '').replace(/题$/, '');
    return ({ 单选: '单选', 单项选择: '单选', single: '单选', radio: '单选', 多选: '多选', 多项选择: '多选', multiple: '多选', checkbox: '多选', 判断: '判断', 判断正误: '判断', boolean: '判断' })[type.toLowerCase()] || type;
  }

  function optionKey(options) { return JSON.stringify((options || []).map(option => normalize(option.text)).sort()); }
  function questionKey(record) { return JSON.stringify([normalizeType(record.type), normalize(record.question)]); }
  function correctKey(record) { return JSON.stringify((record.correctTexts || []).map(normalize).sort()); }
  function groupKey(record) { return questionKey(record) + '\n' + optionKey(record.options); }
  function normalizedLabel(value) { return String(value || '').normalize('NFKC').trim().toUpperCase().replace(/[.、:：)]$/, ''); }

  function getIndex(snapshot) {
    if (!snapshot || !Array.isArray(snapshot.records)) return new Map();
    const saved = cache.get(snapshot);
    if (saved && saved.revision === snapshot.revision && saved.records === snapshot.records) return saved.index;
    const index = new Map();
    snapshot.records.forEach(record => {
      if (!ROLES.includes(record.role)) return;
      const key = record.role + '\n' + groupKey(record);
      if (!index.has(key)) index.set(key, []);
      index.get(key).push(record);
    });
    cache.set(snapshot, { revision: snapshot.revision, records: snapshot.records, index });
    return index;
  }

  function sourceIdentity(value) {
    if (!value) return '';
    try {
      const url = new URL(value, 'https://local.invalid');
      const route = url.hash.startsWith('#/') ? new URL(url.hash.slice(1), url.origin) : url;
      for (const params of [route.searchParams, url.searchParams]) {
        for (const [key, id] of params) {
          if (/^(course_?id|exam_?id|paper_?id|training_?id|lesson_?id)$/i.test(key) && id) return key.toLowerCase().replace(/_/g, '') + ':' + id;
        }
      }
      const exam = route.pathname.match(/\/exam\/([^/]+)\/(?:questions|exercise)\/?$/i);
      if (exam) return 'examid:' + decodeURIComponent(exam[1]);
      // A source path works after a domain/IP change, while title parameters do not identify a course.
      const params = new URLSearchParams(route.search);
      ['title', 'flag', 'name'].forEach(key => params.delete(key));
      params.sort();
      return route.pathname + (params.size ? '?' + params.toString() : '');
    } catch (_) { return String(value); }
  }

  function result(status, reason, records, labels, texts) {
    return { status, reason, records: records || [], correctLabels: labels || [], correctTexts: texts || [] };
  }

  function match(question, context, snapshot) {
    context = context || {};
    if (!ROLES.includes(context.role)) return result('unsupported', '请先选择主操、班长或副操');
    if (!question || !['单选', '多选', '判断'].includes(normalizeType(question.type))) return result('unsupported', '当前题型暂不支持自动选择');
    if (!normalize(question.question) || !Array.isArray(question.options) || question.options.length < 2) return result('unsupported', '题干或选项尚未完整加载');
    if ((question.questionImages && question.questionImages.length) || question.options.some(option => !normalize(option.text) || (option.images && option.images.length))) return result('unsupported', '含图片的题目需要人工核对');
    const currentTexts = question.options.map(option => normalize(option.text));
    const currentLabels = question.options.map(option => normalizedLabel(option.label));
    if (new Set(currentTexts).size !== currentTexts.length || new Set(currentLabels).size !== currentLabels.length || currentLabels.some(label => !/^[A-H]$/.test(label))) return result('unsupported', '当前选项文字或字母重复，无法唯一映射');
    let records = getIndex(snapshot).get(context.role + '\n' + groupKey(question)) || [];
    if (!records.length) return result('missing', '所选岗位题库没有题型、题干和全部选项均一致的记录');
    let sourceMatched = false;
    const identity = sourceIdentity(context.sourceUrl);
    if (identity) {
      const exactSource = records.filter(record => record.sourceUrl && sourceIdentity(record.sourceUrl) === identity);
      if (exactSource.length) { records = exactSource; sourceMatched = true; }
    }
    const course = courseNormalize(context.course);
    if (course) {
      const exactCourse = records.filter(record => courseNormalize(record.course) === course);
      if (exactCourse.length) { records = exactCourse; sourceMatched = true; }
    }
    const answers = new Set(records.map(correctKey));
    if (answers.size > 1) return result('conflict', '相同题干与选项存在不同答案；当前课程来源未能唯一确定', records);
    const wanted = records[0].correctTexts || [];
    const wantedKeys = wanted.map(normalize);
    if (!wantedKeys.length || new Set(wantedKeys).size !== wantedKeys.length || wantedKeys.some(text => !currentTexts.includes(text))) return result('unsupported', '题库参考答案无法唯一对应当前选项', records);
    const selected = question.options.filter(option => wantedKeys.includes(normalize(option.text)));
    if (normalizeType(question.type) !== '多选' && selected.length !== 1) return result('unsupported', '单选/判断题的参考答案数量不正确', records);
    // Keep label/text pairs in current-page order, but obtain each text from bank evidence.
    const evidenceTexts = selected.map(option => wanted.find(text => normalize(text) === normalize(option.text)));
    return result('matched', sourceMatched ? '岗位、课程、题干及选项完全匹配' : '岗位、题干及选项完全匹配，所有来源答案一致', records, selected.map(option => normalizedLabel(option.label)), evidenceTexts);
  }

  function search(query, settings, snapshot) {
    settings = settings || {};
    const role = settings.role;
    const empty = reason => ({ items: [], total: 0, reason, role: role || '', query: String(query || ''), hasMore: false });
    if (!ROLES.includes(role)) return empty('请先选择主操、班长或副操');
    const fullQuery = searchNormalize(query);
    if (!fullQuery) return empty('请输入题干、关键词或选项文字');
    const tokens = fullQuery.split(/\s+/).filter(Boolean);
    const course = courseNormalize(settings.course);
    const records = snapshot && Array.isArray(snapshot.records) ? snapshot.records : [];
    const groups = new Map(), conflicts = new Map();
    records.forEach(record => {
      if (record.role !== role || (course && courseNormalize(record.course) !== course)) return;
      const baseKey = groupKey(record), answerKey = correctKey(record), key = baseKey + '\n' + answerKey;
      if (!conflicts.has(baseKey)) conflicts.set(baseKey, new Set());
      conflicts.get(baseKey).add(answerKey);
      if (!groups.has(key)) groups.set(key, { ...record, sources: [], conflict: false, sourceCount: 0, _baseKey: baseKey, _sources: new Set() });
      const group = groups.get(key);
      const source = { role: record.role, course: record.course, sourceUrl: record.sourceUrl || '', number: record.number };
      const sourceKey = JSON.stringify(source);
      if (!group._sources.has(sourceKey)) { group._sources.add(sourceKey); group.sources.push(source); group.sourceCount++; }
    });
    const items = [];
    groups.forEach(group => {
      const stem = searchNormalize(group.question);
      const optionText = (group.options || []).map(option => searchNormalize(option.text)).join('\n');
      const answerText = (group.correctTexts || []).map(searchNormalize).join('\n');
      const haystack = stem + '\n' + optionText + '\n' + answerText;
      if (!tokens.every(token => haystack.includes(token))) return;
      let score = stem === fullQuery ? 10000 : stem.includes(fullQuery) ? 5000 : 0;
      tokens.forEach(token => { score += stem.includes(token) ? 100 : optionText.includes(token) ? 30 : 10; });
      group.conflict = conflicts.get(group._baseKey).size > 1;
      delete group._baseKey; delete group._sources;
      items.push({ ...group, score });
    });
    items.sort((left, right) => right.score - left.score || left.question.localeCompare(right.question, 'zh-CN') || left.course.localeCompare(right.course, 'zh-CN') || left.number - right.number);
    const total = items.length;
    const limit = Math.max(1, Math.min(100, Number(settings.limit) || 20));
    const offset = Math.max(0, Math.floor(Number(settings.offset) || 0));
    return { items: items.slice(offset, offset + limit), total, role, query: String(query), reason: total ? '' : '当前岗位未找到符合条件的题目', hasMore: offset + limit < total };
  }

  const api = Object.freeze({ version: '2.0.0', normalize, searchNormalize, normalizeType, optionKey, questionKey, sourceIdentity, match, search });
  root.YianAnswerMatcher = api;
  if (typeof module !== 'undefined' && module.exports) module.exports = api;
})(typeof window !== 'undefined' ? window : globalThis);