import 'dart:convert';

import 'package:flutter/foundation.dart';
import 'package:webview_flutter/webview_flutter.dart';

import '../../data/json_schedule_import.dart';
import 'school_navigation_policy.dart';
import 'school_page_adapter.dart';

enum SchoolConnectionState {
  signedOut,
  authenticating,
  connected,
  expired,
  unknown,
}

class SchoolSession extends ChangeNotifier {
  SchoolSession() {
    web = WebViewController()
      ..setJavaScriptMode(JavaScriptMode.unrestricted)
      ..setNavigationDelegate(
        NavigationDelegate(
          onNavigationRequest: (request) {
            final uri = Uri.tryParse(request.url);
            if (uri == null ||
                !SchoolNavigationPolicy.canNavigate(
                  uri,
                  isMainFrame: request.isMainFrame,
                )) {
              message = '学校跳转到了其他地址，已停止自动交接登录信息。';
              notifyListeners();
              return NavigationDecision.prevent;
            }
            return NavigationDecision.navigate;
          },
          onPageStarted: (_) {
            _pageGeneration++;
            _reader.invalidate();
            pendingDraft = null;
            if (!hasOpened) {
              return;
            }
            _loading = true;
            formReady = false;
            notifyListeners();
          },
          onPageFinished: _loaded,
          onWebResourceError: (error) {
            if (error.isForMainFrame == true) {
              _loading = false;
              message = '学校页面暂时未能加载，请检查网络或使用统一认证入口。';
              notifyListeners();
            }
          },
          onHttpError: (error) async {
            final current = Uri.tryParse(await web.currentUrl() ?? '');
            if (!hasOpened ||
                error.request == null ||
                error.request!.uri != current) {
              return;
            }
            _loading = false;
            message = '学校页面请求未完成，可稍后重试。';
            notifyListeners();
          },
        ),
      );
  }
  late final WebViewController web;
  final _reader = SchoolReader(SchoolPageAdapter());
  SchoolConnectionState connectionState = SchoolConnectionState.signedOut;
  bool _loading = false,
      _submitting = false,
      hasOpened = false,
      formReady = false;
  bool get busy => _loading || _submitting || _reader.busy;
  int _pageGeneration = 0;
  ImportDraft? pendingDraft;
  String message = '请通过学校统一身份认证登录。';
  String get statusLabel => switch (connectionState) {
    SchoolConnectionState.signedOut => '未登录',
    SchoolConnectionState.authenticating => '请在学校页面完成认证',
    SchoolConnectionState.connected => '学校认证已确认',
    SchoolConnectionState.expired => '学校登录已过期',
    SchoolConnectionState.unknown => '学校页面已打开 · 等待完整课表',
  };
  static final authUrl = Uri.parse(
    'https://idas.uestc.edu.cn/authserver/login',
  );
  static final timetableUrl = Uri.parse(
    'https://yjsjy.uestc.edu.cn/pyxx/pygl/xskbcx/index/1',
  );
  Future<void> open() => openTimetable();
  Future<void> openTimetable() async {
    hasOpened = true;
    _loading = true;
    pendingDraft = null;
    message = '正在打开研究生课表页面…';
    notifyListeners();
    try {
      await web.loadRequest(timetableUrl);
    } catch (_) {
      _loading = false;
      message = '学校课表页面无法打开，请检查校园网络。';
      notifyListeners();
    }
  }

  Future<void> openAuthentication() async {
    hasOpened = true;
    _loading = true;
    message = '正在准备学校认证…';
    notifyListeners();
    try {
      await web.loadRequest(authUrl);
    } catch (_) {
      _loading = false;
      message = '学校认证页面暂时不可用。';
      notifyListeners();
    }
  }

  static const _readyScript = """(() => {
    if (location.origin !== 'https://idas.uestc.edu.cn' || location.pathname !== '/authserver/login') return false;
    const f = document.querySelector('.login-main #pwdFromId');
    if (!f || f.method.toLowerCase() !== 'post') return false;
    const action = new URL(f.action, location.href);
    return action.origin === location.origin && action.pathname === '/authserver/login'
      && !!f.querySelector('#username') && !!f.querySelector('#password')
      && !!f.querySelector('#saltPassword') && !!f.querySelector('#pwdEncryptSalt')
      && !!f.querySelector('#login_submit') && typeof window.startLogin === 'function'
      && typeof window.encryptPassword === 'function' && typeof window.checkUserCaptcha === 'function';
  })()""";
  bool _truth(Object value) => value == true || value.toString() == 'true';
  Future<void> _loaded(String url) async {
    if (!hasOpened) {
      return;
    }
    _loading = false;
    final generation = _pageGeneration;
    final uri = Uri.tryParse(url);
    if (uri != null && SchoolNavigationPolicy.canInjectCredentials(uri)) {
      connectionState = connectionState == SchoolConnectionState.connected
          ? SchoolConnectionState.expired
          : SchoolConnectionState.authenticating;
      try {
        final ready = _truth(
          await web.runJavaScriptReturningResult(_readyScript),
        );
        if (!hasOpened || generation != _pageGeneration) return;
        formReady = ready;
      } catch (_) {
        if (!hasOpened || generation != _pageGeneration) return;
        formReady = false;
      }
      message = formReady ? '可以使用应用界面登录；验证码会在学校页面完成。' : '请使用学校原页面完成认证。';
    } else if (uri != null && SchoolNavigationPolicy.isTimetable(uri)) {
      connectionState = SchoolConnectionState.unknown;
      message = '已打开课表页面，正在核对课程结构。';
      try {
        final draft = await readTimetable();
        if (!hasOpened || generation != _pageGeneration) return;
        pendingDraft = draft;
        connectionState = SchoolConnectionState.connected;
      } catch (error) {
        if (!hasOpened || generation != _pageGeneration) return;
        message = error is UnsupportedSchoolLayout
            ? error.toString()
            : '课表读取未完成，已有课表保持不变。';
      }
    } else {
      connectionState = SchoolConnectionState.unknown;
      message = '可点击右上角日历打开学校课表。';
    }
    notifyListeners();
  }

  Future<void> submitCredentials(String username, String password) async {
    if (busy) return;
    _submitting = true;
    message = '正在交接学校认证…';
    notifyListeners();
    try {
      final url = Uri.tryParse(await web.currentUrl() ?? '');
      if (url == null ||
          !SchoolNavigationPolicy.canInjectCredentials(url) ||
          !_truth(await web.runJavaScriptReturningResult(_readyScript))) {
        throw StateError('学校表单尚未准备好，请使用学校页面登录');
      }
      final result = await web.runJavaScriptReturningResult('''(() => {
        if (!($_readyScript)) return false;
        const f = document.querySelector('.login-main #pwdFromId');
        const u = f.querySelector('#username'), p = f.querySelector('#password');
        u.value = ${jsonEncode(username)}; p.value = ${jsonEncode(password)};
        p.removeAttribute('readonly');
        u.dispatchEvent(new Event('input', {bubbles:true}));
        p.dispatchEvent(new Event('input', {bubbles:true}));
        window.checkUserCaptcha(); return true;
      })()''');
      if (!_truth(result)) throw StateError('学校表单已变化，请使用学校页面登录');
      var settled = false;
      for (var i = 0; i < 20; i++) {
        if (_truth(
          await web.runJavaScriptReturningResult(
            '!!window.jQuery && window.jQuery.active === 0',
          ),
        )) {
          settled = true;
          break;
        }
        await Future<void>.delayed(const Duration(milliseconds: 200));
      }
      final current = Uri.tryParse(await web.currentUrl() ?? '');
      if (!settled ||
          current == null ||
          !SchoolNavigationPolicy.canInjectCredentials(current)) {
        message = '请在学校页面继续完成验证。';
        return;
      }
      await web.runJavaScript('''(() => {
        if (!($_readyScript)) return;
        window.startLogin(document.querySelector('.login-main #pwdFromId #login_submit'));
      })()''');
      message = '已交给学校处理；如有验证码，请在学校页面完成。';
    } catch (_) {
      message = '登录交接未完成，请使用学校页面继续。';
    } finally {
      _submitting = false;
      notifyListeners();
    }
  }

  Future<ImportDraft> readTimetable() async {
    final uri = Uri.tryParse(await web.currentUrl() ?? '');
    if (uri == null) throw UnsupportedSchoolLayout();
    return _reader.read(uri, () async {
      final raw = await web.runJavaScriptReturningResult(
        'JSON.stringify(document.documentElement.outerHTML)',
      );
      final value = raw is String ? raw : raw.toString();
      try {
        final decoded = jsonDecode(value);
        return decoded is String ? decoded : value;
      } catch (_) {
        return value;
      }
    });
  }

  Future<void> logout() async {
    _pageGeneration++;
    _reader.invalidate();
    hasOpened = false;
    await WebViewCookieManager().clearCookies();
    await web.clearCache();
    await web.clearLocalStorage();
    await web.loadHtmlString('<html></html>');
    _loading = false;
    hasOpened = false;
    pendingDraft = null;
    formReady = false;
    connectionState = SchoolConnectionState.signedOut;
    message = '已退出学校登录。';
    notifyListeners();
  }
}