import 'dart:async';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:google_fonts/google_fonts.dart';
import 'package:go_router/go_router.dart';
import '../../../core/services/auth_proxy_service.dart';

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

  @override
  State<SignupScreen> createState() => _SignupScreenState();
}

class _SignupScreenState extends State<SignupScreen> {
  final _formKey = GlobalKey<FormState>();
  int _currentStep = 1; // 1: 인증, 2: 정보, 3: 비밀번호

  // Controllers
  final _emailController = TextEditingController();
  final _emailCodeController = TextEditingController();
  final _phoneController = TextEditingController();
  final _phoneCodeController = TextEditingController();
  final _nameController = TextEditingController();
  final _passwordController = TextEditingController();
  final _confirmPasswordController = TextEditingController();
  final _deptController = TextEditingController();

  // State
  bool _isEmailVerified = false;
  bool _isPhoneVerified = false;
  String _affiliationType = 'GENERAL';
  String? _companyCode;
  bool _termsAccepted = false;
  bool _privacyAccepted = false;
  bool _isLoading = false;

  // Inline Errors
  String? _emailError;
  String? _phoneError;
  String? _passwordError;
  String? _confirmPasswordError;

  // Timers
  Timer? _emailTimer;
  int _emailSeconds = 0;
  Timer? _phoneTimer;
  int _phoneSeconds = 0;

  @override
  void dispose() {
    _emailTimer?.cancel();
    _phoneTimer?.cancel();
    _emailController.dispose();
    _emailCodeController.dispose();
    _phoneController.dispose();
    _phoneCodeController.dispose();
    _nameController.dispose();
    _passwordController.dispose();
    _confirmPasswordController.dispose();
    _deptController.dispose();
    super.dispose();
  }

  // --- Logic Methods ---

  void _startTimer(String type) {
    if (type == 'email') {
      _emailSeconds = 300;
      _emailTimer?.cancel();
      _emailTimer = Timer.periodic(const Duration(seconds: 1), (timer) {
        if (!mounted) return;
        setState(() {
          if (_emailSeconds > 0) _emailSeconds--;
          else timer.cancel();
        });
      });
    } else {
      _phoneSeconds = 180;
      _phoneTimer?.cancel();
      _phoneTimer = Timer.periodic(const Duration(seconds: 1), (timer) {
        if (!mounted) return;
        setState(() {
          if (_phoneSeconds > 0) _phoneSeconds--;
          else timer.cancel();
        });
      });
    }
  }

  String _formatTime(int seconds) {
    final m = seconds ~/ 60;
    final s = seconds % 60;
    return '${m.toString().padLeft(2, '0')}:${s.toString().padLeft(2, '0')}';
  }

  Future<void> _sendEmailCode() async {
    final email = _emailController.text.trim();
    final emailRegex = RegExp(r'^[\w-\.]+@([\w-]+\.)+[\w-]{2,4}$');
    if (!emailRegex.hasMatch(email)) {
      setState(() => _emailError = '유효한 이메일 형식이 아닙니다.');
      return;
    }

    setState(() { _isLoading = true; _emailError = null; });
    try {
      final available = await AuthProxyService.checkEmailAvailability(email);
      if (!available) {
        setState(() => _emailError = '이미 가입된 이메일입니다.');
        return;
      }
      await AuthProxyService.sendSignupCode(email, 'email');
      _startTimer('email');
    } catch (e) {
      setState(() => _emailError = '발송 실패: $e');
    } finally {
      setState(() => _isLoading = false);
    }
  }

  Future<void> _verifyEmailCode() async {
    final code = _emailCodeController.text.trim();
    if (code.length != 6) return;
    try {
      final success = await AuthProxyService.verifySignupCode(_emailController.text.trim(), 'email', code);
      if (success) {
        setState(() {
          _isEmailVerified = true;
          _emailTimer?.cancel();
          _emailSeconds = 0;
          _emailError = null;
        });
      } else {
        setState(() => _emailError = '인증코드가 일치하지 않습니다.');
      }
    } catch (e) {
      setState(() => _emailError = '인증 실패: $e');
    }
  }

  Future<void> _sendPhoneCode() async {
    final phone = _phoneController.text.trim();
    if (phone.isEmpty) return;
    setState(() { _isLoading = true; _phoneError = null; });
    try {
      await AuthProxyService.sendSignupCode(phone, 'phone');
      _startTimer('phone');
    } catch (e) {
      setState(() => _phoneError = '발송 실패: $e');
    } finally {
      setState(() => _isLoading = false);
    }
  }

  Future<void> _verifyPhoneCode() async {
    final code = _phoneCodeController.text.trim();
    if (code.length != 6) return;
    try {
      final success = await AuthProxyService.verifySignupCode(_phoneController.text.trim(), 'phone', code);
      if (success) {
        setState(() {
          _isPhoneVerified = true;
          _phoneTimer?.cancel();
          _phoneSeconds = 0;
          _phoneError = null;
        });
      } else {
        setState(() => _phoneError = '인증코드가 일치하지 않습니다.');
      }
    } catch (e) {
      setState(() => _phoneError = '인증 실패: $e');
    }
  }

  Future<void> _handleSignup() async {
    if (_passwordController.text != _confirmPasswordController.text) {
      setState(() => _confirmPasswordError = '비밀번호가 일치하지 않습니다.');
      return;
    }
    if (!_formKey.currentState!.validate()) return;
    if (!_termsAccepted || !_privacyAccepted) return;

    setState(() {
      _isLoading = true;
      _passwordError = null;
    });

    try {
      await AuthProxyService.signup(
        email: _emailController.text.trim(),
        password: _passwordController.text,
        name: _nameController.text.trim(),
        phone: _phoneController.text.trim(),
        affiliationType: _affiliationType,
        companyCode: _affiliationType == 'AFFILIATE' ? _companyCode : null,
        department: _deptController.text.trim().isEmpty ? (_affiliationType == 'GENERAL' ? 'External' : '') : _deptController.text.trim(),
        termsAccepted: true,
      );
      if (mounted) _showSuccessDialog();
    } catch (e) {
      String eStr = e.toString().toLowerCase();
      setState(() {
        if (eStr.contains('uppercase')) _passwordError = '대문자가 최소 1개 이상 포함되어야 합니다.';
        else if (eStr.contains('lowercase')) _passwordError = '소문자가 최소 1개 이상 포함되어야 합니다.';
        else if (eStr.contains('digit') || eStr.contains('number')) _passwordError = '숫자가 최소 1개 이상 포함되어야 합니다.';
        else if (eStr.contains('symbol') || eStr.contains('special')) _passwordError = '특수문자가 최소 1개 이상 포함되어야 합니다.';
        else if (eStr.contains('length') || eStr.contains('12 characters')) _passwordError = '비밀번호는 최소 12자 이상이어야 합니다.';
        else _passwordError = '가입 실패: $e';
      });
    } finally {
      setState(() => _isLoading = false);
    }
  }

  void _showSuccessDialog() {
    showDialog(
      context: context,
      barrierDismissible: false,
      builder: (context) => AlertDialog(
        title: const Text('회원가입 완료'),
        content: const Text('성공적으로 가입되었습니다.'),
        actions: [TextButton(onPressed: () => context.go('/login'), child: const Text('로그인하기'))],
      ),
    );
  }

  // --- UI Components ---

  Widget _buildStepIndicator() {
    return Padding(
      padding: const EdgeInsets.symmetric(vertical: 20),
      child: Row(
        children: [
          _stepCircle(1, '본인인증'),
          _stepLine(1),
          _stepCircle(2, '정보입력'),
          _stepLine(2),
          _stepCircle(3, '비밀번호'),
        ],
      ),
    );
  }

  Widget _stepCircle(int step, String label) {
    bool isDone = _currentStep > step;
    bool isCurrent = _currentStep == step;
    return Column(
      children: [
        CircleAvatar(
          radius: 15,
          backgroundColor: isDone ? Colors.green : (isCurrent ? Colors.black : Colors.grey[300]),
          child: isDone ? const Icon(Icons.check, size: 16, color: Colors.white) : Text('$step', style: TextStyle(color: isCurrent ? Colors.white : Colors.black54, fontSize: 12)),
        ),
        const SizedBox(height: 4),
        Text(label, style: TextStyle(fontSize: 10, color: isCurrent ? Colors.black : Colors.grey, fontWeight: isCurrent ? FontWeight.bold : FontWeight.normal)),
      ],
    );
  }

  Widget _stepLine(int afterStep) {
    return Expanded(
      child: Container(
        margin: const EdgeInsets.only(bottom: 16, left: 4, right: 4),
        height: 2,
        color: _currentStep > afterStep ? Colors.green : Colors.grey[300],
      ),
    );
  }

  Widget _buildStep1() {
    return Column(
      crossAxisAlignment: CrossAxisAlignment.stretch,
      children: [
        Text('이메일 인증', style: GoogleFonts.outfit(fontSize: 16, fontWeight: FontWeight.w600)),
        const SizedBox(height: 12),
        Row(
          children: [
            Expanded(
              child: TextFormField(
                controller: _emailController,
                decoration: InputDecoration(labelText: '이메일 주소', border: const OutlineInputBorder(), errorText: _emailError),
                readOnly: _isEmailVerified,
              ),
            ),
            const SizedBox(width: 8),
            SizedBox(
              height: 55,
              child: ElevatedButton(
                onPressed: (_isEmailVerified || _isLoading) ? null : _sendEmailCode,
                child: Text(_emailSeconds > 0 ? '재발송' : '인증요청'),
              ),
            ),
          ],
        ),
        if (_emailSeconds > 0 && !_isEmailVerified) ...[
          const SizedBox(height: 8),
          TextFormField(
            controller: _emailCodeController,
            decoration: InputDecoration(
              labelText: '이메일 인증코드 6자리',
              suffixText: _formatTime(_emailSeconds),
              border: const OutlineInputBorder(),
            ),
            keyboardType: TextInputType.number,
            inputFormatters: [FilteringTextInputFormatter.digitsOnly, LengthLimitingTextInputFormatter(6)],
            onChanged: (val) { if(val.length == 6) _verifyEmailCode(); },
          ),
        ],
        if (_isEmailVerified) const Padding(
          padding: EdgeInsets.only(top: 8),
          child: Text('✅ 이메일 인증이 완료되었습니다.', style: TextStyle(color: Colors.green, fontSize: 13)),
        ),
        const SizedBox(height: 24),
        Text('휴대폰 인증', style: GoogleFonts.outfit(fontSize: 16, fontWeight: FontWeight.w600)),
        const SizedBox(height: 12),
        Row(
          children: [
            Expanded(
              child: TextFormField(
                controller: _phoneController,
                decoration: InputDecoration(labelText: '휴대폰 번호 (-없이)', border: const OutlineInputBorder(), errorText: _phoneError),
                readOnly: _isPhoneVerified,
                keyboardType: TextInputType.phone,
              ),
            ),
            const SizedBox(width: 8),
            SizedBox(
              height: 55,
              child: ElevatedButton(
                onPressed: (_isPhoneVerified || _isLoading) ? null : _sendPhoneCode,
                child: Text(_phoneSeconds > 0 ? '재발송' : '인증요청'),
              ),
            ),
          ],
        ),
        if (_phoneSeconds > 0 && !_isPhoneVerified) ...[
          const SizedBox(height: 8),
          TextFormField(
            controller: _phoneCodeController,
            decoration: InputDecoration(
              labelText: '휴대폰 인증코드 6자리',
              suffixText: _formatTime(_phoneSeconds),
              border: const OutlineInputBorder(),
            ),
            keyboardType: TextInputType.number,
            inputFormatters: [FilteringTextInputFormatter.digitsOnly, LengthLimitingTextInputFormatter(6)],
            onChanged: (val) { if(val.length == 6) _verifyPhoneCode(); },
          ),
        ],
        if (_isPhoneVerified) const Padding(
          padding: EdgeInsets.only(top: 8),
          child: Text('✅ 휴대폰 인증이 완료되었습니다.', style: TextStyle(color: Colors.green, fontSize: 13)),
        ),
      ],
    );
  }

  Widget _buildStep2() {
    return Column(
      crossAxisAlignment: CrossAxisAlignment.stretch,
      children: [
        Text('사용자 정보를 입력해주세요', style: GoogleFonts.outfit(fontSize: 16, fontWeight: FontWeight.w600)),
        const SizedBox(height: 16),
        TextFormField(
          controller: _nameController,
          decoration: const InputDecoration(labelText: '이름', border: OutlineInputBorder()),
        ),
        const SizedBox(height: 16),
        DropdownButtonFormField<String>(
          value: _affiliationType,
          decoration: const InputDecoration(labelText: '소속 유형', border: OutlineInputBorder()),
          items: const [
            DropdownMenuItem(value: 'GENERAL', child: Text('일반 사용자')),
            DropdownMenuItem(value: 'AFFILIATE', child: Text('가족사 임직원')),
          ],
          onChanged: (val) => setState(() { _affiliationType = val!; }),
        ),
        const SizedBox(height: 16),
        if (_affiliationType == 'AFFILIATE') ...[
          DropdownButtonFormField<String>(
            value: _companyCode,
            decoration: const InputDecoration(labelText: '가족사 선택', border: OutlineInputBorder()),
            items: const [
              DropdownMenuItem(value: 'HANMAC', child: Text('한맥')),
              DropdownMenuItem(value: 'SAMAN', child: Text('삼안')),
              DropdownMenuItem(value: 'PTC', child: Text('PTC')),
              DropdownMenuItem(value: 'JANGHEON', child: Text('장헌')),
              DropdownMenuItem(value: 'BARON', child: Text('바론')),
              DropdownMenuItem(value: 'HALLA', child: Text('한라')),
            ],
            onChanged: (val) => setState(() => _companyCode = val),
          ),
          const SizedBox(height: 16),
        ],
        TextFormField(
          controller: _deptController,
          decoration: InputDecoration(
            labelText: _affiliationType == 'AFFILIATE' ? '부서명' : '소속 정보 (선택)',
            border: const OutlineInputBorder()
          ),
        ),
      ],
    );
  }

  Widget _buildStep3() {
    // 실시간 비밀번호 체크 로직
    String p = _passwordController.text;
    bool hasUpper = p.contains(RegExp(r'[A-Z]'));
    bool hasLower = p.contains(RegExp(r'[a-z]'));
    bool hasDigit = p.contains(RegExp(r'[0-9]'));
    bool hasSpecial = p.contains(RegExp(r'[!@#$%^&*(),.?":{}|<>]'));
    bool hasLength = p.length >= 12;

    return Column(
      crossAxisAlignment: CrossAxisAlignment.stretch,
      children: [
        Text('보안 설정', style: GoogleFonts.outfit(fontSize: 16, fontWeight: FontWeight.w600)),
        const SizedBox(height: 16),
        TextFormField(
          controller: _passwordController,
          obscureText: true,
          onChanged: (_) => setState(() {}),
          decoration: InputDecoration(
            labelText: '비밀번호',
            border: const OutlineInputBorder(),
            errorText: _passwordError,
          ),
        ),
        const SizedBox(height: 8),
        // 실시간 체크 표시 UI
        Wrap(
          spacing: 10,
          children: [
            _cryptoCheck('12자 이상', hasLength),
            _cryptoCheck('대문자', hasUpper),
            _cryptoCheck('소문자', hasLower),
            _cryptoCheck('숫자', hasDigit),
            _cryptoCheck('특수문자', hasSpecial),
          ],
        ),
        const SizedBox(height: 16),
        TextFormField(
          controller: _confirmPasswordController,
          obscureText: true,
          onChanged: (val) {
            setState(() {
              if (val != _passwordController.text) {
                _confirmPasswordError = '비밀번호가 일치하지 않습니다.';
              } else {
                _confirmPasswordError = null;
              }
            });
          },
          decoration: InputDecoration(
            labelText: '비밀번호 확인', 
            border: const OutlineInputBorder(),
            errorText: _confirmPasswordError,
          ),
        ),
        const SizedBox(height: 24),
        CheckboxListTile(
          title: const Text('이용약관 및 개인정보 처리방침 동의', style: TextStyle(fontSize: 13)),
          value: _termsAccepted && _privacyAccepted,
          onChanged: (val) => setState(() { _termsAccepted = val!; _privacyAccepted = val; }),
          controlAffinity: ListTileControlAffinity.leading,
          contentPadding: EdgeInsets.zero,
        ),
      ],
    );
  }

  Widget _cryptoCheck(String label, bool isValid) {
    return Row(
      mainAxisSize: MainAxisSize.min,
      children: [
        Icon(isValid ? Icons.check_circle : Icons.circle_outlined, size: 14, color: isValid ? Colors.green : Colors.grey),
        const SizedBox(width: 4),
        Text(label, style: TextStyle(fontSize: 11, color: isValid ? Colors.green : Colors.grey)),
      ],
    );
  }

  @override
  Widget build(BuildContext context) {
    bool canGoNext = false;
    if (_currentStep == 1 && _isEmailVerified && _isPhoneVerified) canGoNext = true;
    if (_currentStep == 2 && _nameController.text.isNotEmpty && (_affiliationType == 'GENERAL' || _companyCode != null)) canGoNext = true;

    return Scaffold(
      backgroundColor: Colors.white,
      appBar: AppBar(
        title: Text('회원가입', style: GoogleFonts.outfit(fontWeight: FontWeight.bold)),
        elevation: 0,
        backgroundColor: Colors.white,
        foregroundColor: Colors.black,
      ),
      body: SafeArea(
        child: Column(
          children: [
            Padding(
              padding: const EdgeInsets.symmetric(horizontal: 40),
              child: _buildStepIndicator(),
            ),
            Expanded(
              child: SingleChildScrollView(
                padding: const EdgeInsets.all(24),
                child: Form(
                  key: _formKey,
                  child: _currentStep == 1 ? _buildStep1() : (_currentStep == 2 ? _buildStep2() : _buildStep3()),
                ),
              ),
            ),
            Padding(
              padding: const EdgeInsets.all(24),
              child: Row(
                children: [
                  if (_currentStep > 1) ...[
                    Expanded(
                      child: OutlinedButton(
                        onPressed: () => setState(() => _currentStep--),
                        style: OutlinedButton.styleFrom(minimumSize: const Size.fromHeight(55)),
                        child: const Text('이전'),
                      ),
                    ),
                    const SizedBox(width: 12),
                  ],
                  Expanded(
                    child: FilledButton(
                      onPressed: _currentStep < 3 
                        ? (canGoNext ? () => setState(() => _currentStep++) : null)
                        : (_isLoading || !_termsAccepted ? null : _handleSignup),
                      style: FilledButton.styleFrom(
                        minimumSize: const Size.fromHeight(55),
                        backgroundColor: Colors.black,
                      ),
                      child: _isLoading 
                        ? const SizedBox(height: 20, width: 20, child: CircularProgressIndicator(color: Colors.white, strokeWidth: 2))
                        : Text(_currentStep < 3 ? '다음 단계' : '가입 완료'),
                    ),
                  ),
                ],
              ),
            ),
          ],
        ),
      ),
    );
  }
}