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

import '../../../app/app_controller.dart';
import '../../../data/json_schedule_import.dart';
import '../../../domain/exam_schedule.dart';
import '../../profile/import_preview.dart';
import 'session.dart';
import 'exam_query_picker.dart';

class UndergraduateAuthPage extends StatefulWidget {
  const UndergraduateAuthPage({
    super.key,
    required this.session,
    required this.controller,
  });
  final UndergraduateSession session;
  final AppController controller;
  @override
  State<UndergraduateAuthPage> createState() => _UndergraduateAuthPageState();
}

class _UndergraduateAuthPageState extends State<UndergraduateAuthPage> {
  bool _saving = false;
  Object? _handled;
  String? _saveError;
  @override
  void initState() {
    super.initState();
    widget.session.addListener(_changed);
    WidgetsBinding.instance.addPostFrameCallback((_) {
      if (mounted) {
        widget.session.setReadingActive(true);
        _changed();
      }
    });
  }

  void _changed() {
    if (!mounted) return;
    setState(() {});
    final s = widget.session, result = s.pendingDraft ?? s.pendingExams;
    if (_saving || result == null || identical(_handled, result)) return;
    _handled = result;
    _saving = true;
    final generation = s.pageGeneration;
    WidgetsBinding.instance.addPostFrameCallback((_) async {
      if (!mounted) return;
      await _save(s.pendingDraft, s.pendingExams, generation);
    });
  }

  Future<void> _save(
    ImportDraft? draft,
    ExamSchedule? exams,
    int generation,
  ) async {
    final s = widget.session,
        controller = widget.controller,
        route = ModalRoute.of(context);
    bool current() =>
        mounted &&
        route?.isActive == true &&
        generation == s.pageGeneration &&
        identical(draft, s.pendingDraft) &&
        identical(exams, s.pendingExams);
    try {
      if (!current()) return;
      var saved = false;
      if (draft != null) {
        final replacement =
            controller.snapshot.courses.isNotEmpty &&
            controller.snapshot.schoolTerm != draft.schoolTerm;
        if (replacement || draft.courses.isEmpty) {
          final confirmed = await showModalBottomSheet<bool>(
            context: context,
            isScrollControlled: true,
            showDragHandle: true,
            builder: (_) => ImportPreview(
              draft: draft,
              controller: controller,
              canApply: current,
            ),
          );
          if (!current()) return;
          saved = confirmed == true;
        } else {
          await controller.applyImport(
            draft,
            confirmedEmpty: false,
            canApply: current,
          );
          saved = controller.lastError == null;
        }
      } else if (exams != null) {
        await controller.applyExams(exams, canApply: current);
        saved = controller.lastError == null;
      }
      if (!current()) return;
      if (saved && s.saved(generation: generation)) {
        if (!mounted) return;
        final messenger = ScaffoldMessenger.of(context);
        if (route?.isCurrent == true) Navigator.pop(context);
        messenger.showSnackBar(
          SnackBar(
            content: Text(
              exams != null
                  ? '考试信息已更新'
                  : draft!.courses.any((c) => c.room == '教室待定')
                  ? '课表已导入，部分课程教室待定；请核对学期开始日。'
                  : '课表已导入，请核对学期开始日。',
            ),
          ),
        );
      } else if (controller.lastError != null) {
        _saveError = controller.lastError;
      }
    } finally {
      _saving = false;
      if (mounted) _changed();
    }
  }

  @override
  void dispose() {
    widget.session.removeListener(_changed);
    widget.session.setReadingActive(false);
    super.dispose();
  }

  Future<void> _changeQuery() async {
    final value = await showUndergraduateExamQueryPicker(
      context,
      initial: widget.session.query,
      now: widget.controller.clock(),
    );
    if (!mounted || value == null) return;
    _handled = null;
    _saveError = null;
    await widget.session.openExams(value);
  }

  @override
  Widget build(BuildContext context) {
    final s = widget.session;
    return Scaffold(
      appBar: AppBar(
        title: Text(s.requestingExams ? '本科考试查询' : '本科课表导入'),
        actions: [
          if (s.requestingExams)
            IconButton(
              tooltip: '查询选项',
              onPressed: _saving ? null : _changeQuery,
              icon: const Icon(Icons.tune_rounded),
            ),
          IconButton(
            tooltip: '重新认证',
            onPressed: _saving
                ? null
                : () {
                    _handled = null;
                    _saveError = null;
                    s.reauthenticate();
                  },
            icon: const Icon(Icons.refresh_rounded),
          ),
        ],
      ),
      body: Column(
        children: [
          if (s.busy || _saving) const LinearProgressIndicator(minHeight: 2),
          Container(
            width: double.infinity,
            padding: const EdgeInsets.all(12),
            color: const Color(0xFFEFF6FF),
            child: Text(
              [
                s.message,
                if (s.browserVersion != null) 'Chromium ${s.browserVersion}',
              ].join('\n'),
              style: const TextStyle(fontSize: 12, height: 1.5),
            ),
          ),
          if (s.requestingExams && s.query != null)
            Padding(
              padding: const EdgeInsets.all(8),
              child: Text(
                '${s.query!.term.label} · ${s.query!.orderedTypes.map((t) => t.label).join('、')}',
                style: const TextStyle(fontSize: 12),
              ),
            ),
          if (_saveError != null)
            Padding(
              padding: const EdgeInsets.all(8),
              child: Column(
                children: [
                  Text(_saveError!, style: const TextStyle(fontSize: 12)),
                  TextButton(
                    onPressed: _saving
                        ? null
                        : () {
                            _saveError = null;
                            _handled = null;
                            _changed();
                          },
                    child: const Text('重试保存'),
                  ),
                ],
              ),
            ),
          Expanded(child: WebViewWidget(controller: s.web)),
          if (!s.requestingExams)
            SafeArea(
              top: false,
              child: Padding(
                padding: const EdgeInsets.fromLTRB(16, 8, 16, 10),
                child: SizedBox(
                  width: double.infinity,
                  child: FilledButton.icon(
                    onPressed: _saving || s.busy
                        ? null
                        : () {
                            _handled = null;
                            _saveError = null;
                            s.readCurrentTimetable();
                          },
                    icon: const Icon(Icons.download_rounded),
                    label: const Text('导入当前课表'),
                  ),
                ),
              ),
            ),
        ],
      ),
    );
  }
}