// 👥 교사용 학생 계정 관리 화면 (UI 전용). 신규 학생 계정 추가 폼과 강제 삭제 다이얼로그를 그린다.
// 서버 통신/상태는 lib/function/teacher_student_management_controller.dart가 담당한다.
import 'dart:typed_data';
import 'package:desktop_drop/desktop_drop.dart';
import 'package:flutter/material.dart';
import '../function/excel_file_picker.dart';
import '../function/teacher_student_management_controller.dart';

// 📐 "실시간 출석 확인" 목록(teacher_attendance_page.dart)의 타일 규격과 동일하게 맞춘다.
const double kAttendanceTileWidth = 220;
const double kAttendanceTileHeight = 148;

// -----------------------------------------------------------------------------
// 👥 [서브 화면 2] 학생 계정 관리 란 (추가 양식 폼 + 강제 삭제 다이얼로그 완전 내장)
// -----------------------------------------------------------------------------
class TeacherStudentManagementPage extends StatefulWidget {
  const TeacherStudentManagementPage({super.key});

  @override
  State<TeacherStudentManagementPage> createState() =>
      _TeacherStudentManagementPageState();
}

class _TeacherStudentManagementPageState
    extends State<TeacherStudentManagementPage> {
  final TeacherStudentManagementController _controller =
      TeacherStudentManagementController();
  final TextEditingController _addIdController = TextEditingController();
  final TextEditingController _addNameController = TextEditingController();
  final TextEditingController _addPwController = TextEditingController();
  int? _selectedGrade;
  bool _isDragging = false;

  @override
  void initState() {
    super.initState();
    _controller.init();
  }

  @override
  void dispose() {
    _controller.dispose();
    _addIdController.dispose();
    _addNameController.dispose();
    _addPwController.dispose();
    super.dispose();
  }

  // ➕ [학생 추가 버튼 동작]
  Future<void> _addStudentAccount() async {
    final sId = _addIdController.text.trim();
    final sName = _addNameController.text.trim();
    final sPw = _addPwController.text.trim();

    if (sId.isEmpty || sName.isEmpty || sPw.isEmpty) {
      ScaffoldMessenger.of(
        context,
      ).showSnackBar(const SnackBar(content: Text('⚠️ 모든 입력란을 채워주세요.')));
      return;
    }

    final (success, message) = await _controller.addStudentAccount(
      studentId: sId,
      name: sName,
      password: sPw,
      grade: _selectedGrade,
    );
    if (!mounted) return;
    if (success) {
      _addIdController.clear();
      _addNameController.clear();
      _addPwController.clear();
      setState(() => _selectedGrade = null);
    }
    ScaffoldMessenger.of(
      context,
    ).showSnackBar(SnackBar(content: Text(message)));
  }

  // 📄 [파일 선택 버튼 동작] "파일 선택"으로 엑셀 고르기
  Future<void> _pickExcelFile() async {
    final bytes = await pickExcelFileBytes();
    if (bytes == null) return;
    if (!mounted) return;
    await _handleExcelBytes(bytes);
  }

  // 📄 엑셀 바이트를 파싱해서 미리보기 다이얼로그를 띄운다 (드래그/파일선택 공용).
  Future<void> _handleExcelBytes(Uint8List bytes) async {
    List<BulkStudentRow> rows;
    try {
      rows = _controller.parseExcelBytes(bytes);
    } catch (e) {
      if (!mounted) return;
      ScaffoldMessenger.of(
        context,
      ).showSnackBar(SnackBar(content: Text('❌ 엑셀 파일을 읽는 데 실패했습니다: $e')));
      return;
    }
    if (rows.isEmpty) {
      if (!mounted) return;
      ScaffoldMessenger.of(context).showSnackBar(
        const SnackBar(
          content: Text('⚠️ 유효한 학생 데이터를 찾지 못했습니다. (1행은 머리글로 건너뜁니다)'),
        ),
      );
      return;
    }
    _showBulkPreviewDialog(rows);
  }

  // 📋 [일괄 등록 확인 팝업] 엑셀에서 뽑아낸 명단을 미리 보여주고 확정받는다.
  void _showBulkPreviewDialog(List<BulkStudentRow> rows) {
    showDialog(
      context: context,
      builder: (context) => AlertDialog(
        shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(24)),
        title: Text('📄 ${rows.length}명 확인됨'),
        content: SizedBox(
          width: 400,
          child: Column(
            mainAxisSize: MainAxisSize.min,
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              const Text(
                '아래 명단으로 계정을 일괄 생성합니다 (초기 비밀번호: 1234).',
                style: TextStyle(color: Colors.black54, fontSize: 13),
              ),
              const SizedBox(height: 12),
              ConstrainedBox(
                constraints: const BoxConstraints(maxHeight: 300),
                child: ListView.builder(
                  shrinkWrap: true,
                  itemCount: rows.length,
                  itemBuilder: (context, i) {
                    final row = rows[i];
                    return ListTile(
                      dense: true,
                      leading: CircleAvatar(
                        radius: 14,
                        child: Text(
                          '${i + 1}',
                          style: const TextStyle(fontSize: 11),
                        ),
                      ),
                      title: Text('${row.name} (${row.studentId})'),
                      trailing: Text(
                        row.grade != null ? '${row.grade}학년' : '미배정',
                        style: TextStyle(color: Colors.grey[600]),
                      ),
                    );
                  },
                ),
              ),
            ],
          ),
        ),
        actions: [
          TextButton(
            onPressed: () => Navigator.pop(context),
            child: const Text('취소', style: TextStyle(color: Colors.grey)),
          ),
          ElevatedButton(
            onPressed: () {
              Navigator.pop(context);
              _runBulkImport(rows);
            },
            style: ElevatedButton.styleFrom(
              backgroundColor: Colors.orange,
              foregroundColor: Colors.white,
              shape: RoundedRectangleBorder(
                borderRadius: BorderRadius.circular(12),
              ),
            ),
            child: Text('${rows.length}명 일괄 등록'),
          ),
        ],
      ),
    );
  }

  // 🚀 실제 일괄 등록 실행 + 진행 상황 표시 + 결과 요약 팝업.
  Future<void> _runBulkImport(List<BulkStudentRow> rows) async {
    showDialog(
      context: context,
      barrierDismissible: false,
      builder: (context) => ListenableBuilder(
        listenable: _controller,
        builder: (context, _) => AlertDialog(
          shape: RoundedRectangleBorder(
            borderRadius: BorderRadius.circular(24),
          ),
          content: Row(
            children: [
              const CircularProgressIndicator(),
              const SizedBox(width: 20),
              Text(
                '등록 중... (${_controller.bulkDone}/${_controller.bulkTotal})',
              ),
            ],
          ),
        ),
      ),
    );

    final result = await _controller.bulkAddStudents(rows);

    if (!mounted) return;
    Navigator.pop(context); // 진행 팝업 닫기

    showDialog(
      context: context,
      builder: (context) => AlertDialog(
        shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(24)),
        title: Text(
          result.failures.isEmpty ? '✅ 일괄 등록 완료' : '⚠️ 일괄 등록 완료 (일부 실패)',
        ),
        content: SizedBox(
          width: 400,
          child: Column(
            mainAxisSize: MainAxisSize.min,
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              Text(
                '성공 ${result.successCount}명 / 실패 ${result.failures.length}명',
              ),
              if (result.failures.isNotEmpty) ...[
                const SizedBox(height: 12),
                const Text(
                  '실패 목록',
                  style: TextStyle(fontWeight: FontWeight.bold),
                ),
                const SizedBox(height: 6),
                ConstrainedBox(
                  constraints: const BoxConstraints(maxHeight: 200),
                  child: SingleChildScrollView(
                    child: Text(
                      result.failures.join('\n'),
                      style: const TextStyle(fontSize: 12, color: Colors.red),
                    ),
                  ),
                ),
              ],
            ],
          ),
        ),
        actions: [
          TextButton(
            onPressed: () => Navigator.pop(context),
            child: const Text('확인'),
          ),
        ],
      ),
    );
  }

  // 🏫 [목록 행의 "학년" 칩] 눌러서 바로 학년 변경 (미배정/1/2/3학년 중 선택).
  Future<void> _showGradeMenu(
    BuildContext tileContext,
    String studentId,
    String studentName,
    int? currentGrade,
  ) async {
    final RenderBox box = tileContext.findRenderObject() as RenderBox;
    final Offset position = box.localToGlobal(Offset.zero);

    final selected = await showMenu<int?>(
      context: tileContext,
      position: RelativeRect.fromLTRB(
        position.dx,
        position.dy + box.size.height,
        position.dx,
        0,
      ),
      items: const [
        PopupMenuItem(value: null, child: Text('미배정')),
        PopupMenuItem(value: 1, child: Text('1학년')),
        PopupMenuItem(value: 2, child: Text('2학년')),
        PopupMenuItem(value: 3, child: Text('3학년')),
      ],
    );
    if (selected == currentGrade) return; // 취소했거나 같은 값 선택
    if (!mounted) return;

    final (_, message) = await _controller.updateStudentGrade(
      studentId: studentId,
      grade: selected,
    );
    if (!mounted) return;
    ScaffoldMessenger.of(
      context,
    ).showSnackBar(SnackBar(content: Text(message)));
  }

  // 🔓 [목록 행의 "기기 리셋" 버튼] 학생이 폰을 바꿨을 때 등록 초기화.
  void _confirmResetDevice(String studentId, String studentName) {
    showDialog(
      context: context,
      builder: (ctx) => AlertDialog(
        title: const Text(
          '⚠️ 기기 등록 초기화',
          style: TextStyle(fontWeight: FontWeight.bold, color: Colors.purple),
        ),
        content: Text('$studentName 학생의 스마트폰 기기 등록과 비밀번호(1234)를 초기화하시겠습니까?'),
        actions: [
          TextButton(
            onPressed: () => Navigator.pop(ctx),
            child: const Text('취소', style: TextStyle(color: Colors.grey)),
          ),
          ElevatedButton(
            style: ElevatedButton.styleFrom(
              backgroundColor: Colors.purple,
              foregroundColor: Colors.white,
            ),
            onPressed: () async {
              Navigator.pop(ctx);
              final (_, message) = await _controller.resetDevice(
                studentId,
                studentName,
              );
              if (!mounted) return;
              ScaffoldMessenger.of(
                context,
              ).showSnackBar(SnackBar(content: Text(message)));
            },
            child: const Text('초기화 승인'),
          ),
        ],
      ),
    );
  }

  // 🚨 [목록 행의 삭제 버튼] 계정 완전 삭제 확인 팝업.
  void _confirmDeleteStudent(String studentId, String studentName) {
    showDialog(
      context: context,
      builder: (ctx) => AlertDialog(
        shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(24)),
        title: Row(
          children: [
            Icon(Icons.warning_amber_rounded, color: Colors.red[700]),
            const SizedBox(width: 10),
            const Text(
              '계정 완전 삭제',
              style: TextStyle(fontWeight: FontWeight.bold, fontSize: 18),
            ),
          ],
        ),
        content: Text(
          '정말로 $studentName ($studentId) 학생의 계정을 영구 삭제하시겠습니까?\n이 작업은 되돌릴 수 없습니다.',
        ),
        actions: [
          TextButton(
            onPressed: () => Navigator.pop(ctx),
            child: const Text('취소', style: TextStyle(color: Colors.grey)),
          ),
          ElevatedButton(
            style: ElevatedButton.styleFrom(
              backgroundColor: Colors.red[600],
              foregroundColor: Colors.white,
            ),
            onPressed: () async {
              Navigator.pop(ctx);
              final (_, message) = await _controller.deleteStudentAccount(
                studentId,
              );
              if (!mounted) return;
              ScaffoldMessenger.of(
                context,
              ).showSnackBar(SnackBar(content: Text(message)));
            },
            child: const Text('영구 삭제'),
          ),
        ],
      ),
    );
  }

  // 🏷️ 섹션 제목 (색 인디케이터 바 + 텍스트).
  Widget _sectionTitle(String text, {Color color = Colors.orange}) {
    return Row(
      children: [
        Container(
          width: 4,
          height: 16,
          decoration: BoxDecoration(
            color: color,
            borderRadius: BorderRadius.circular(2),
          ),
        ),
        const SizedBox(width: 8),
        Text(
          text,
          style: const TextStyle(fontSize: 18, fontWeight: FontWeight.bold),
        ),
      ],
    );
  }

  // 📝 [정사각형 박스 1] 신규 학생 계정 추가 폼. 박스가 작아도 버튼까지 다 보이도록 촘촘하게 배치.
  Widget _buildAddAccountBox() {
    const InputDecoration Function(String, IconData) fieldDecoration =
        _compactFieldDecoration;
    return Container(
      padding: const EdgeInsets.all(10),
      decoration: BoxDecoration(
        color: Colors.white,
        borderRadius: BorderRadius.circular(24),
        boxShadow: [
          BoxShadow(
            color: Colors.black.withValues(alpha: 0.04),
            blurRadius: 16,
          ),
        ],
      ),
      child: SingleChildScrollView(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            TextField(
              controller: _addIdController,
              keyboardType: TextInputType.number,
              style: const TextStyle(fontSize: 12),
              decoration: fieldDecoration('학번', Icons.badge),
            ),
            const SizedBox(height: 4),
            TextField(
              controller: _addNameController,
              style: const TextStyle(fontSize: 12),
              decoration: fieldDecoration('이름', Icons.person),
            ),
            const SizedBox(height: 4),
            TextField(
              controller: _addPwController,
              obscureText: true,
              style: const TextStyle(fontSize: 12),
              decoration: fieldDecoration('초기 비밀번호', Icons.lock),
            ),
            const SizedBox(height: 4),
            DropdownButtonFormField<int>(
              initialValue: _selectedGrade,
              style: const TextStyle(fontSize: 12, color: Colors.black87),
              decoration: fieldDecoration('학년 (선택)', Icons.class_),
              items: const [
                DropdownMenuItem(value: 1, child: Text('1학년')),
                DropdownMenuItem(value: 2, child: Text('2학년')),
                DropdownMenuItem(value: 3, child: Text('3학년')),
              ],
              onChanged: (value) => setState(() => _selectedGrade = value),
            ),
            const SizedBox(height: 6),
            SizedBox(
              width: double.infinity,
              height: 30,
              child: ElevatedButton(
                onPressed: _controller.isWorking ? null : _addStudentAccount,
                style: ElevatedButton.styleFrom(
                  backgroundColor: Colors.orange,
                  foregroundColor: Colors.white,
                  padding: EdgeInsets.zero,
                  shape: RoundedRectangleBorder(
                    borderRadius: BorderRadius.circular(10),
                  ),
                ),
                child: _controller.isWorking
                    ? const SizedBox(
                        width: 16,
                        height: 16,
                        child: CircularProgressIndicator(
                          color: Colors.white,
                          strokeWidth: 2,
                        ),
                      )
                    : const Text(
                        '학생 등록 완료',
                        style: TextStyle(
                          fontWeight: FontWeight.bold,
                          fontSize: 12,
                        ),
                      ),
              ),
            ),
          ],
        ),
      ),
    );
  }

  static InputDecoration _compactFieldDecoration(String label, IconData icon) {
    return InputDecoration(
      labelText: label,
      labelStyle: const TextStyle(fontSize: 12),
      prefixIcon: Icon(icon, size: 16),
      isDense: true,
      contentPadding: const EdgeInsets.symmetric(vertical: 4, horizontal: 8),
    );
  }

  // 📤 [정사각형 박스 2] 엑셀 일괄 등록 드롭존.
  Widget _buildExcelBox() {
    return DropTarget(
      onDragEntered: (_) => setState(() => _isDragging = true),
      onDragExited: (_) => setState(() => _isDragging = false),
      onDragDone: (details) async {
        setState(() => _isDragging = false);
        if (details.files.isEmpty) return;
        final bytes = await details.files.first.readAsBytes();
        if (!mounted) return;
        await _handleExcelBytes(bytes);
      },
      child: InkWell(
        onTap: _pickExcelFile,
        borderRadius: BorderRadius.circular(24),
        child: Container(
          width: double.infinity,
          height: double.infinity,
          padding: const EdgeInsets.all(20),
          decoration: BoxDecoration(
            color: _isDragging ? Colors.orange[50] : Colors.white,
            borderRadius: BorderRadius.circular(24),
            border: Border.all(
              color: _isDragging ? Colors.orange : Colors.grey.shade300,
              width: _isDragging ? 2 : 1,
            ),
          ),
          child: Column(
            mainAxisAlignment: MainAxisAlignment.center,
            children: [
              Icon(
                Icons.upload_file_rounded,
                size: 40,
                color: _isDragging ? Colors.orange : Colors.grey[400],
              ),
              const SizedBox(height: 12),
              Text(
                _isDragging ? '여기에 놓으세요' : '엑셀 파일을 드래그하거나 눌러서 선택',
                textAlign: TextAlign.center,
                style: TextStyle(
                  fontWeight: FontWeight.bold,
                  color: _isDragging ? Colors.orange[800] : Colors.black87,
                ),
              ),
              const SizedBox(height: 4),
              Text(
                '.xlsx · 1행은 머리글, A열=학번 B열=이름 C열=학년(선택)',
                style: TextStyle(fontSize: 12, color: Colors.grey[500]),
                textAlign: TextAlign.center,
              ),
            ],
          ),
        ),
      ),
    );
  }

  // 🧑‍🎓 [학생 목록 타일] 아이콘/이름/상태/액션을 모두 중앙 정렬한 정사각 타일.
  Widget _buildStudentTile(Map<String, dynamic> student) {
    final String studentId = student['id'].toString();
    final String studentName = student['name'].toString();
    final int? grade = student['grade'] as int?;
    final bool needsReset = student['device'] == '초기화 필요';

    return Container(
      padding: const EdgeInsets.all(14),
      decoration: BoxDecoration(
        color: Colors.white,
        borderRadius: BorderRadius.circular(20),
        boxShadow: [
          BoxShadow(
            color: Colors.black.withValues(alpha: 0.03),
            blurRadius: 12,
            offset: const Offset(0, 4),
          ),
        ],
      ),
      child: Column(
        mainAxisAlignment: MainAxisAlignment.center,
        crossAxisAlignment: CrossAxisAlignment.center,
        children: [
          Container(
            padding: const EdgeInsets.all(8),
            decoration: BoxDecoration(
              color: (needsReset ? Colors.red : Colors.blue).withValues(
                alpha: 0.1,
              ),
              shape: BoxShape.circle,
            ),
            child: Icon(
              needsReset ? Icons.lock_reset : Icons.person,
              size: 18,
              color: needsReset ? Colors.red : Colors.blue,
            ),
          ),
          const SizedBox(height: 8),
          Text(
            '$studentName ($studentId)',
            textAlign: TextAlign.center,
            maxLines: 1,
            overflow: TextOverflow.ellipsis,
            style: const TextStyle(fontWeight: FontWeight.bold, fontSize: 15),
          ),
          const SizedBox(height: 4),
          Text(
            needsReset ? '초기화 대기중' : '정상 등록',
            textAlign: TextAlign.center,
            style: TextStyle(
              fontSize: 11.5,
              color: needsReset ? Colors.red[700] : Colors.grey[600],
              fontWeight: needsReset ? FontWeight.bold : FontWeight.normal,
            ),
          ),
          const SizedBox(height: 6),
          Wrap(
            alignment: WrapAlignment.center,
            spacing: 2,
            runSpacing: 2,
            children: [
              Builder(
                builder: (chipContext) => ActionChip(
                  visualDensity: VisualDensity.compact,
                  materialTapTargetSize: MaterialTapTargetSize.shrinkWrap,
                  labelPadding: const EdgeInsets.symmetric(horizontal: 6),
                  label: Text(
                    grade != null ? '$grade학년' : '미배정',
                    style: const TextStyle(fontSize: 11),
                  ),
                  onPressed: () => _showGradeMenu(
                    chipContext,
                    studentId,
                    studentName,
                    grade,
                  ),
                ),
              ),
              IconButton(
                icon: const Icon(
                  Icons.lock_reset,
                  color: Colors.purple,
                  size: 18,
                ),
                tooltip: '기기 리셋',
                padding: EdgeInsets.zero,
                constraints: const BoxConstraints(minWidth: 28, minHeight: 28),
                onPressed: () => _confirmResetDevice(studentId, studentName),
              ),
              IconButton(
                icon: const Icon(
                  Icons.delete_forever_rounded,
                  color: Colors.redAccent,
                  size: 18,
                ),
                tooltip: '계정 영구 삭제',
                padding: EdgeInsets.zero,
                constraints: const BoxConstraints(minWidth: 28, minHeight: 28),
                onPressed: () => _confirmDeleteStudent(studentId, studentName),
              ),
            ],
          ),
        ],
      ),
    );
  }

  @override
  Widget build(BuildContext context) {
    return ListenableBuilder(
      listenable: _controller,
      builder: (context, _) {
        return Scaffold(
          backgroundColor: Colors.grey[100],
          appBar: AppBar(
            title: const Text(
              '⚙️ 학생 통합 관리 센터',
              style: TextStyle(fontWeight: FontWeight.bold),
            ),
            backgroundColor: Colors.orange,
            foregroundColor: Colors.white,
            elevation: 0,
          ),
          body: SingleChildScrollView(
            padding: const EdgeInsets.all(24.0),
            child: LayoutBuilder(
              builder: (context, constraints) {
                // 🖥️ 웹(넓은 화면)은 계정 추가/엑셀 등록을 정사각형 2칸으로 나란히, 폰은 기존처럼 세로로 쌓는다.
                // 📐 학생 목록 타일은 "실시간 출석 확인" 목록의 타일(220x148)과 동일하게 맞춘다.
                final bool isWide = constraints.maxWidth >= 800;
                final double listWidth = constraints.maxWidth;
                // 📉 계정 추가 / 엑셀 등록 칸: 정사각형 기본 크기의 25%(+ 버튼까지 다 보이도록 확대).
                final double formSquareSize =
                    ((constraints.maxWidth - 20) / 2) * 0.25 * 1.45;

                final Widget addBoxColumn = Column(
                  crossAxisAlignment: CrossAxisAlignment.start,
                  children: [
                    _sectionTitle('신규 학생 계정 추가'),
                    const SizedBox(height: 16),
                    SizedBox(
                      width: isWide ? formSquareSize : double.infinity,
                      height: isWide ? formSquareSize : null,
                      child: _buildAddAccountBox(),
                    ),
                  ],
                );

                final Widget excelBoxColumn = Column(
                  crossAxisAlignment: CrossAxisAlignment.start,
                  children: [
                    _sectionTitle('엑셀로 한번에 추가 (신입생 등)'),
                    const SizedBox(height: 16),
                    SizedBox(
                      width: isWide ? formSquareSize : double.infinity,
                      height: isWide ? formSquareSize : 240,
                      child: _buildExcelBox(),
                    ),
                  ],
                );

                return Column(
                  crossAxisAlignment: CrossAxisAlignment.start,
                  children: [
                    isWide
                        ? Row(
                            crossAxisAlignment: CrossAxisAlignment.start,
                            children: [
                              addBoxColumn,
                              const SizedBox(width: 20),
                              excelBoxColumn,
                            ],
                          )
                        : Column(
                            crossAxisAlignment: CrossAxisAlignment.start,
                            children: [
                              addBoxColumn,
                              const SizedBox(height: 24),
                              excelBoxColumn,
                            ],
                          ),
                    const SizedBox(height: 36),

                    // 🏷️ 인디케이터 바 (전체 학생 목록) — 위 두 칸을 합친 폭에 맞춘다.
                    SizedBox(
                      width: listWidth,
                      child: Column(
                        crossAxisAlignment: CrossAxisAlignment.start,
                        children: [
                          Row(
                            children: [
                              _sectionTitle('전체 학생 목록', color: Colors.blue),
                              const Spacer(),
                              IconButton(
                                icon: const Icon(Icons.refresh_rounded),
                                onPressed: _controller.isLoadingStudents
                                    ? null
                                    : _controller.fetchStudents,
                                tooltip: '새로고침',
                              ),
                            ],
                          ),
                          const SizedBox(height: 8),
                          const Text(
                            '학년 칩을 눌러 학년을 바꾸고, 기기 리셋은 학생이 폰을 바꿨을 때 사용하세요.',
                            style: TextStyle(
                              color: Colors.black54,
                              fontSize: 12,
                            ),
                          ),
                          const SizedBox(height: 12),
                          _controller.isLoadingStudents
                              ? const Padding(
                                  padding: EdgeInsets.symmetric(vertical: 40),
                                  child: Center(
                                    child: CircularProgressIndicator(),
                                  ),
                                )
                              : _controller.students.isEmpty
                              ? const Padding(
                                  padding: EdgeInsets.symmetric(vertical: 24),
                                  child: Center(
                                    child: Text(
                                      '가입된 학생 계정이 없습니다.',
                                      style: TextStyle(color: Colors.grey),
                                    ),
                                  ),
                                )
                              : GridView.builder(
                                  shrinkWrap: true,
                                  physics: const NeverScrollableScrollPhysics(),
                                  gridDelegate:
                                      const SliverGridDelegateWithMaxCrossAxisExtent(
                                        maxCrossAxisExtent:
                                            kAttendanceTileWidth,
                                        mainAxisExtent: kAttendanceTileHeight,
                                        crossAxisSpacing: 12,
                                        mainAxisSpacing: 12,
                                      ),
                                  itemCount: _controller.students.length,
                                  itemBuilder: (context, index) =>
                                      _buildStudentTile(
                                        _controller.students[index],
                                      ),
                                ),
                        ],
                      ),
                    ),
                  ],
                );
              },
            ),
          ),
        );
      },
    );
  }
}