// 🔑 로그인 화면 (UI 전용). 입력폼/다이얼로그/화면 이동만 담당한다.
// 인증 로직/서버 통신은 lib/function/login_controller.dart가 담당한다.
import 'package:flutter/material.dart';
import '../config.dart' show schoolName;
import '../function/login_controller.dart';
import '../function/session_store.dart';
import '../theme/app_palette.dart';
import 'app_notice.dart';
import 'main_dashboard.dart';
import 'teacher_register_screen.dart';

// -------------------------------------------------------------
// 1. 로그인 화면 (LoginScreen)
// -------------------------------------------------------------

class LoginScreen extends StatefulWidget {
  const LoginScreen({super.key});

  @override
  State<LoginScreen> createState() => _LoginScreenState();
}

class _LoginScreenState extends State<LoginScreen> {
  final LoginController _controller = LoginController();
  final TextEditingController _idController = TextEditingController();
  final TextEditingController _pwController = TextEditingController();
  bool _keepLoggedIn = true;

  @override
  void dispose() {
    _controller.dispose();
    _idController.dispose();
    _pwController.dispose();
    super.dispose();
  }

  Future<void> _login() async {
    final result = await _controller.login(
      _idController.text.trim(),
      _pwController.text.trim(),
    );
    if (!mounted) return;

    switch (result.outcome) {
      case LoginOutcome.error:
        _showErrorDialog(result.errorMessage!);
        break;
      case LoginOutcome.masterSuccess:
        if (_keepLoggedIn) {
          await SessionStore.save(
            SavedSession(
              userId: result.studentId!,
              userName: result.name!,
              role: 'student',
              isDeviceMatched: true,
            ),
          );
        } else {
          await SessionStore.clear();
        }
        if (!mounted) return;
        AppNotice.show(context, '개발자 최고 권한으로 로그인되었습니다.');
        Navigator.pushReplacement(
          context,
          MaterialPageRoute(
            builder: (context) => MainDashboard(
              userId: result.studentId!,
              userName: result.name!,
              role: 'student',
              isDeviceMatched: true,
            ),
          ),
        );
        break;
      case LoginOutcome.needsPasswordChange:
        _showFirstLoginPasswordDialog(
          result.studentId!,
          result.name!,
          result.role!,
          result.isDeviceMatched,
          result.grade,
        );
        break;
      case LoginOutcome.success:
        AppNotice.show(context, '${result.name}님 환영합니다!');
        _navigateBasedOnRole(
          result.role!,
          result.studentId!,
          result.name!,
          result.isDeviceMatched,
          result.grade,
        );
        break;
    }
  }

  // 🛠️ 초기 비밀번호 변경 팝업창 (기기 매칭 데이터 파라미터 추가)
  void _showFirstLoginPasswordDialog(
    String studentId,
    String name,
    String role,
    bool isDeviceMatched,
    int? grade,
  ) {
    final TextEditingController newPwController = TextEditingController();

    showDialog(
      context: context,
      barrierDismissible: false,
      builder: (BuildContext dialogContext) {
        bool isUpdating = false;

        return StatefulBuilder(
          builder: (context, setDialogState) {
            return AlertDialog(
              title: const Text(
                '초기 비밀번호 변경',
                style: TextStyle(fontWeight: FontWeight.bold),
              ),
              content: Column(
                mainAxisSize: MainAxisSize.min,
                children: [
                  const Text(
                    '보안을 위해 새로운 비밀번호를 설정해 주세요.',
                    style: TextStyle(color: Colors.redAccent),
                  ),
                  const SizedBox(height: 16),
                  TextField(
                    controller: newPwController,
                    obscureText: true,
                    decoration: const InputDecoration(
                      labelText: '새 비밀번호',
                      border: OutlineInputBorder(),
                      prefixIcon: Icon(Icons.lock_reset),
                    ),
                  ),
                ],
              ),
              actions: [
                isUpdating
                    ? const Padding(
                        padding: EdgeInsets.only(right: 20.0),
                        child: CircularProgressIndicator(),
                      )
                    : ElevatedButton(
                        style: ElevatedButton.styleFrom(
                          backgroundColor: AppPalette.ink,
                          foregroundColor: Colors.white,
                        ),
                        onPressed: () async {
                          String newPassword = newPwController.text.trim();
                          if (newPassword.isEmpty) {
                            AppNotice.show(context, '새 비밀번호를 입력해 주세요.');
                            return;
                          }

                          setDialogState(() => isUpdating = true);

                          final (success, message) = await _controller
                              .changePassword(
                                studentId: studentId,
                                newPassword: newPassword,
                              );
                          setDialogState(() => isUpdating = false);

                          if (success) {
                            Navigator.pop(dialogContext);
                            AppNotice.show(context, message);
                            _navigateBasedOnRole(
                              role,
                              studentId,
                              name,
                              isDeviceMatched,
                              grade,
                            );
                          } else {
                            AppNotice.show(context, message);
                          }
                        },
                        child: const Text('변경하고 시작하기'),
                      ),
              ],
            );
          },
        );
      },
    );
  }

  // 🆕 권한별 화면 이동시 기기 일치 여부 파라미터(`isDeviceMatched`) 수신 및 대시보드 전달
  Future<void> _navigateBasedOnRole(
    String role,
    String studentId,
    String name,
    bool isDeviceMatched,
    int? grade,
  ) async {
    if (_keepLoggedIn) {
      await SessionStore.save(
        SavedSession(
          userId: studentId,
          userName: name,
          role: role,
          isDeviceMatched: isDeviceMatched,
          grade: grade,
        ),
      );
    } else {
      await SessionStore.clear();
    }
    if (!mounted) return;
    Navigator.pushReplacement(
      context,
      MaterialPageRoute(
        builder: (context) => MainDashboard(
          userId: studentId,
          userName: name,
          role: role,
          isDeviceMatched: isDeviceMatched,
          grade: grade,
        ),
      ),
    );
  }

  void _showErrorDialog(String message) {
    showDialog(
      context: context,
      builder: (ctx) => AlertDialog(
        title: const Text(
          '인증 실패',
          style: TextStyle(fontWeight: FontWeight.bold),
        ),
        content: Text(message),
        actions: [
          TextButton(
            onPressed: () => Navigator.pop(ctx),
            child: const Text('확인'),
          ),
        ],
      ),
    );
  }

  void _showLegacyPasswordDialog(
    String title,
    String correctPassword,
    Widget nextPage,
  ) {
    final TextEditingController passwordController = TextEditingController();
    showDialog(
      context: context,
      barrierDismissible: false,
      builder: (BuildContext dialogContext) {
        return AlertDialog(
          title: Text('$title 권한 인증 (기존 방식)'),
          content: TextField(
            controller: passwordController,
            obscureText: true,
            keyboardType: TextInputType.number,
            textInputAction: TextInputAction.done,
            onSubmitted: (value) {
              if (value == correctPassword) {
                Navigator.pop(dialogContext);
                Navigator.push(
                  context,
                  MaterialPageRoute(builder: (context) => nextPage),
                );
              } else {
                AppNotice.show(context, '비밀번호가 올바르지 않습니다.');
              }
            },
            decoration: const InputDecoration(
              hintText: '비밀번호 4자리를 입력하세요',
              border: OutlineInputBorder(),
            ),
          ),
          actions: [
            TextButton(
              onPressed: () => Navigator.pop(dialogContext),
              child: const Text('취소', style: TextStyle(color: Colors.grey)),
            ),
            ElevatedButton(
              onPressed: () {
                if (passwordController.text == correctPassword) {
                  Navigator.pop(dialogContext);
                  Navigator.push(
                    context,
                    MaterialPageRoute(builder: (context) => nextPage),
                  );
                } else {
                  AppNotice.show(context, '비밀번호가 올바르지 않습니다.');
                }
              },
              child: const Text('인증하기'),
            ),
          ],
        );
      },
    );
  }

  @override
  Widget build(BuildContext context) {
    return ListenableBuilder(
      listenable: _controller,
      builder: (context, _) {
        return Scaffold(
          backgroundColor: AppPalette.mist,
          body: Center(
            child: SingleChildScrollView(
              padding: const EdgeInsets.all(24.0),
              child: ConstrainedBox(
                constraints: const BoxConstraints(maxWidth: 420),
                child: Column(
                  mainAxisAlignment: MainAxisAlignment.center,
                  children: [
                    const Icon(Icons.school, size: 80, color: AppPalette.ink),
                    const SizedBox(height: 16),
                    Text(
                      '$schoolName 모니터',
                      style: const TextStyle(
                        fontSize: 26,
                        fontWeight: FontWeight.bold,
                        color: AppPalette.ink,
                      ),
                    ),
                    const SizedBox(height: 8),
                    const Text(
                      '학생 편의 및 학교생활 도우미',
                      style: TextStyle(color: Colors.grey, fontSize: 15),
                    ),
                    const SizedBox(height: 40),
                    TextField(
                      controller: _idController,
                      textInputAction: TextInputAction.next,
                      decoration: const InputDecoration(
                        labelText: '학번 또는 교직원 번호',
                        border: OutlineInputBorder(),
                        prefixIcon: Icon(Icons.person),
                      ),
                    ),
                    const SizedBox(height: 16),
                    TextField(
                      controller: _pwController,
                      obscureText: true,
                      textInputAction: TextInputAction.done,
                      onSubmitted: (_) => _login(),
                      decoration: const InputDecoration(
                        labelText: '비밀번호',
                        border: OutlineInputBorder(),
                        prefixIcon: Icon(Icons.lock),
                      ),
                    ),
                    const SizedBox(height: 8),
                    InkWell(
                      onTap: () =>
                          setState(() => _keepLoggedIn = !_keepLoggedIn),
                      borderRadius: BorderRadius.circular(8),
                      child: Padding(
                        padding: const EdgeInsets.symmetric(vertical: 4),
                        child: Row(
                          mainAxisSize: MainAxisSize.min,
                          children: [
                            Checkbox(
                              value: _keepLoggedIn,
                              activeColor: AppPalette.ink,
                              onChanged: (value) =>
                                  setState(() => _keepLoggedIn = value ?? true),
                            ),
                            const Text(
                              '로그인 상태 유지',
                              style: TextStyle(color: AppPalette.ink),
                            ),
                          ],
                        ),
                      ),
                    ),
                    const SizedBox(height: 16),
                    _controller.isLoading
                        ? const CircularProgressIndicator()
                        : SizedBox(
                            width: double.infinity,
                            height: 55,
                            child: ElevatedButton(
                              style: ElevatedButton.styleFrom(
                                backgroundColor: AppPalette.ink,
                                foregroundColor: Colors.white,
                                shape: RoundedRectangleBorder(
                                  borderRadius: BorderRadius.circular(12),
                                ),
                              ),
                              onPressed: _login,
                              child: const Text(
                                '로그인',
                                style: TextStyle(
                                  fontSize: 18,
                                  fontWeight: FontWeight.bold,
                                ),
                              ),
                            ),
                          ),
                    const SizedBox(height: 4),
                    TextButton(
                      onPressed: () => Navigator.push(
                        context,
                        MaterialPageRoute(
                          builder: (context) => const TeacherRegisterScreen(),
                        ),
                      ),
                      child: const Text(
                        '선생님이신가요? 교사 회원가입 하기',
                        style: TextStyle(
                          color: AppPalette.ink,
                          fontWeight: FontWeight.bold,
                        ),
                      ),
                    ),
                    const Divider(height: 40),
                    Row(
                      mainAxisAlignment: MainAxisAlignment.spaceEvenly,
                      children: [
                        TextButton.icon(
                          icon: const Icon(
                            Icons.gavel,
                            size: 18,
                            color: Colors.grey,
                          ),
                          label: const Text(
                            '교사 간편인증',
                            style: TextStyle(color: Colors.grey),
                          ),
                          onPressed: () => _showLegacyPasswordDialog(
                            '선생님',
                            '1234',
                            const MainDashboard(role: 'teacher'),
                          ),
                        ),
                        TextButton.icon(
                          icon: const Icon(
                            Icons.settings,
                            size: 18,
                            color: Colors.grey,
                          ),
                          label: const Text(
                            '관리자 간편인증',
                            style: TextStyle(color: Colors.grey),
                          ),
                          onPressed: () => _showLegacyPasswordDialog(
                            '시스템 관리자',
                            '4936',
                            const MainDashboard(role: 'admin'),
                          ),
                        ),
                      ],
                    ),
                  ],
                ),
              ),
            ),
          ),
        );
      },
    );
  }
}