import 'dart:convert';
import 'dart:typed_data';

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

import '../../app/app_controller.dart';
import '../../app/app_theme.dart';
import '../school/school_exam_adapter.dart';

class ExamsPage extends StatelessWidget {
  const ExamsPage({super.key, required this.controller, required this.onSync});
  final AppController controller;
  final VoidCallback onSync;
  Future<void> _import(BuildContext context) async {
    try {
      final file = await FilePicker.pickFile(
        type: FileType.custom,
        allowedExtensions: ['html', 'htm'],
      );
      if (file == null) return;
      final bytes = BytesBuilder(copy: false);
      var length = 0;
      await for (final chunk in file.readAsByteStream()) {
        length += chunk.length;
        if (length > 2 * 1024 * 1024) {
          throw const FormatException('文件不能超过 2 MB');
        }
        bytes.add(chunk);
      }
      final draft = SchoolExamAdapter.extract(utf8.decode(bytes.takeBytes()));
      if (!context.mounted) return;
      final confirmed = await showDialog<bool>(
        context: context,
        builder: (context) => AlertDialog(
          title: const Text('导入考试信息'),
          content: Text(
            '${draft.semesterLabel} · ${draft.records.length} 门课程\n文件仅包含这个学期；其他学期请从学校查询。将更新本机考试列表，尚未公布的字段显示为“尚未安排”。',
          ),
          actions: [
            TextButton(
              onPressed: () => Navigator.pop(context, false),
              child: const Text('取消'),
            ),
            FilledButton(
              onPressed: () => Navigator.pop(context, true),
              child: const Text('确认导入'),
            ),
          ],
        ),
      );
      if (confirmed == true) {
        await controller.applyExams(draft);
        if (context.mounted) {
          ScaffoldMessenger.of(context).showSnackBar(
            SnackBar(content: Text(controller.lastError ?? '考试信息已导入')),
          );
        }
      }
    } catch (error) {
      if (context.mounted) {
        ScaffoldMessenger.of(context)
            .showSnackBar(SnackBar(content: Text('导入未完成：$error')));
      }
    }
  }

  @override
  Widget build(BuildContext context) {
    final schedule = controller.snapshot.examSchedule;
    return ListView(
      key: const PageStorageKey('exams-scroll'),
      padding: EdgeInsets.fromLTRB(
        22,
        10,
        22,
        140 + MediaQuery.paddingOf(context).bottom,
      ),
      children: [
        const Text(
          '考试',
          style: TextStyle(fontSize: 22, fontWeight: FontWeight.w700),
        ),
        const SizedBox(height: 18),
        Row(
          children: [
            const Expanded(
              child: Text(
                '考试安排',
                style: TextStyle(fontSize: 25, fontWeight: FontWeight.w700),
              ),
            ),
            IconButton(
              tooltip: '从学校更新考试',
              onPressed: onSync,
              icon: const Icon(Icons.sync_rounded),
            ),
            IconButton(
              tooltip: '导入考试 HTML',
              onPressed: () => _import(context),
              icon: const Icon(Icons.file_download_outlined),
            ),
          ],
        ),
        const SizedBox(height: 8),
        if (schedule == null) ...[
          const SizedBox(height: 54),
          const Icon(
            Icons.assignment_outlined,
            size: 64,
            color: Color(0xFF9ABBE8),
          ),
          const SizedBox(height: 20),
          const Text(
            '等待学校公布考试安排',
            textAlign: TextAlign.center,
            style: TextStyle(fontSize: 18, fontWeight: FontWeight.w600),
          ),
          const SizedBox(height: 12),
          const Text(
            '选择学校连接教务系统，或导入学校考试页面的 HTML。',
            textAlign: TextAlign.center,
            style: TextStyle(fontSize: 13, height: 1.8),
          ),
          const SizedBox(height: 24),
          Center(
            child: FilledButton.icon(
              onPressed: onSync,
              icon: const Icon(Icons.school_outlined),
              label: const Text('连接学校考试查询'),
            ),
          ),
        ] else ...[
          Text(
            '${schedule.semesterLabel} · ${schedule.records.length} 门课程',
            style: TextStyle(fontSize: 13, color: ink.withValues(alpha: 0.55)),
          ),
          const SizedBox(height: 18),
          if (schedule.records.isEmpty) const Text('该学期暂无考试课程'),
          for (final exam in schedule.records)
            Padding(
              padding: const EdgeInsets.only(bottom: 14),
              child: SurfaceCard(
                child: Column(
                  crossAxisAlignment: CrossAxisAlignment.start,
                  children: [
                    Text(
                      exam.name,
                      style: const TextStyle(
                        fontSize: 17,
                        fontWeight: FontWeight.w700,
                      ),
                    ),
                    const SizedBox(height: 14),
                    _field(Icons.schedule_rounded, '考试时间', exam.time),
                    _field(Icons.location_on_outlined, '考场', exam.room),
                    _field(Icons.event_seat_outlined, '座位号', exam.seat),
                    if (exam.assessment.isNotEmpty)
                      _field(
                        Icons.assignment_outlined,
                        '考核方式',
                        exam.assessment,
                      ),
                    if (exam.candidate.isNotEmpty)
                      _field(Icons.badge_outlined, '考生编号', exam.candidate),
                    if (exam.sequence.isNotEmpty)
                      _field(
                        Icons.format_list_numbered,
                        '考场顺序号',
                        exam.sequence,
                      ),
                  ],
                ),
              ),
            ),
          const Text(
            '排考信息以学校最新公布为准。',
            textAlign: TextAlign.center,
            style: TextStyle(fontSize: 11, color: Color(0xFF8493A5)),
          ),
        ],
      ],
    );
  }

  Widget _field(IconData icon, String label, String value) => Padding(
    padding: const EdgeInsets.only(bottom: 8),
    child: Row(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        Icon(icon, size: 17, color: const Color(0xFF007AFF)),
        const SizedBox(width: 9),
        Expanded(
          child: Text(
            '$label：${value.isEmpty ? '尚未安排' : value}',
            style: const TextStyle(fontSize: 13, height: 1.5),
          ),
        ),
      ],
    ),
  );
}