import 'dart:convert';

import 'navigation_policy.dart';

const undergraduateProbeBase = r'''(() => {
  const capture=__CAPTURE__;
  const topUrl=location.href;
  const result={topUrl,authenticated:false,pages:[]};
  const trusted=value=>{try{const u=new URL(value);return u.protocol==='https:' && u.hostname==='eams.uestc.edu.cn' &&
    (!u.port || u.port==='443') && !u.username && !u.password && u.pathname.startsWith('/eams/');}catch(_){return false;}};
  if(!trusted(topUrl) || document.querySelector('input[type="password"]'))return JSON.stringify(result);
  const origin=new URL(topUrl).origin,seen=new Set();let total=0;
  const headers=['课程序号','课程名称','考试日期','考试安排','考试地点','座位号','考试情况','考试类型','其它说明'];
  const add=(kind,url,body)=>{
    total+=new TextEncoder().encode(body).byteLength;
    if(total>2*1024*1024)throw new Error('capture_limit');
    result.pages.push({kind,url,html:body});
  };
  const visit=(doc,depth)=>{
    if(!doc || seen.has(doc))return;
    let url;try{url=doc.location.href;}catch(_){return;}
    if(!trusted(url) || new URL(url).origin!==origin || doc.querySelector('input[type="password"]'))return;
    if(depth>4 || seen.size>=16)throw new Error('capture_limit');seen.add(doc);
    const timetable=doc.querySelector('#manualArrangeCourseTable');
    const exams=Array.from(doc.querySelectorAll('table')).filter(table=>{
      const row=table.querySelector('tr');if(!row)return false;
      const values=Array.from(row.children).map(c=>c.textContent.trim());
      return values.length===9 && headers.every((v,i)=>values[i]===v);
    });
    const logout=Array.from(doc.querySelectorAll('a[href]')).some(a=>{try{return new URL(a.getAttribute('href'),url).pathname==='/eams/logout.action';}catch(_){return false;}});
    result.authenticated=result.authenticated || Boolean(logout || timetable || exams.length);
    if(capture && (timetable || exams.length)){
      const fields=Array.from(doc.querySelectorAll('input[name="semester.id"],input[name="examType.id"],input[name="params"]')).map(input=>{
        const clone=input.cloneNode(true);clone.setAttribute('value',input.value);return clone.outerHTML;
      }).join('');
      const scripts=Array.from(doc.querySelectorAll('script')).filter(s=>/new\s+TaskActivity|\bunitCount\s*=|\bvar\s+params\s*=/.test(s.textContent)).map(s=>s.outerHTML).join('');
      if(timetable){
        const roster=Array.from(doc.querySelectorAll('table')).filter(table=>{
          const row=table.querySelector('tr');return row && Array.from(row.children).some(c=>c.textContent.trim()==='课程序号') &&
            Array.from(row.children).some(c=>c.textContent.trim()==='课程代码');
        }).map(t=>t.outerHTML).join('');
        add('timetable',url,fields+timetable.outerHTML+roster+scripts);
      }
      for(const table of exams)add('exams',url,'<form id="stdExamTableForm">'+fields+'</form>'+table.outerHTML+scripts);
    }
    for(const frame of doc.querySelectorAll('iframe,frame')){
      let child;try{child=frame.contentDocument;}catch(_){continue;}visit(child,depth+1);
    }
  };
  try{visit(document,0);}catch(_){result.error='capture_limit';result.pages=[];}
  return JSON.stringify(result);
})()''';

final undergraduateStatusProbeScript = undergraduateProbeBase.replaceAll(
  '__CAPTURE__',
  'false',
);
final undergraduateCaptureScript = undergraduateProbeBase.replaceAll(
  '__CAPTURE__',
  'true',
);

class UndergraduateFragment {
  const UndergraduateFragment(this.kind, this.url, this.html);
  final String kind, html;
  final Uri url;
}

class UndergraduatePageEvidence {
  const UndergraduatePageEvidence(this.authenticated, this.pages);
  final bool authenticated;
  final List<UndergraduateFragment> pages;
  static UndergraduatePageEvidence decode(Object raw, Uri current) {
    try {
      dynamic value = raw;
      for (var i = 0; i < 2 && value is String; i++) {
        value = jsonDecode(value);
      }
      if (value is! Map ||
          value['topUrl'] != current.toString() ||
          value['error'] != null ||
          !UndergraduateNavigationPolicy.canNavigate(
            current,
            isMainFrame: true,
          )) {
        throw const FormatException('页面证据无效');
      }
      final pages = value['pages'];
      if (pages is! List || pages.length > 32) {
        throw const FormatException('页面片段过多');
      }
      var bytes = 0;
      final result = <UndergraduateFragment>[];
      for (final page in pages) {
        if (page is! Map ||
            page['url'] is! String ||
            page['html'] is! String ||
            !const ['timetable', 'exams'].contains(page['kind'])) {
          throw const FormatException('页面片段无效');
        }
        final uri = Uri.parse(page['url'] as String),
            body = page['html'] as String;
        bytes += utf8.encode(body).length;
        if (bytes > 2 * 1024 * 1024 ||
            !UndergraduateNavigationPolicy.isDataPage(current) ||
            !UndergraduateNavigationPolicy.isDataPage(uri) ||
            current.origin != uri.origin) {
          throw const FormatException('页面来源或大小无效');
        }
        result.add(UndergraduateFragment(page['kind'] as String, uri, body));
      }
      if (!UndergraduateNavigationPolicy.isDataPage(current) &&
          (value['authenticated'] == true || result.isNotEmpty)) {
        throw const FormatException('认证页面不能作为数据来源');
      }
      return UndergraduatePageEvidence(
        value['authenticated'] == true,
        List.unmodifiable(result),
      );
    } on FormatException {
      rethrow;
    } catch (_) {
      throw const FormatException('学校页面读取未完成');
    }
  }
}