import 'package:flutter/material.dart';
import 'package:go_router/go_router.dart';
import '../../../core/i18n/locale_utils.dart';
import '../../../core/services/auth_proxy_service.dart';
import '../../../core/ui/toast_service.dart';
import 'package:userfront/i18n.dart';

class ResetPasswordScreen extends StatefulWidget {
  final String? loginId; // Now receiving loginId
  const ResetPasswordScreen({super.key, this.loginId});

  @override
  State<ResetPasswordScreen> createState() => _ResetPasswordScreenState();
}

class _ResetPasswordScreenState extends State<ResetPasswordScreen> {
  final TextEditingController _passwordController = TextEditingController();
  final TextEditingController _confirmPasswordController =
      TextEditingController();
  final _formKey = GlobalKey<FormState>();
  bool _isLoading = false;
  String? _loginId;
  String? _token;
  bool _isPasswordObscured = true;
  bool _isConfirmPasswordObscured = true;
  Map<String, dynamic>? _policy;
  bool _isPolicyLoading = false;

  @override
  void initState() {
    super.initState();
    // 1. Get loginId from GoRouter state if available
    _loginId = widget.loginId;

    // 2. Fallback to URI query parameter if not available via router
    if (_loginId == null || _loginId!.isEmpty) {
      final uri = Uri.base;
      _loginId = uri.queryParameters['loginId'];
    }

    // 토큰도 함께 읽어놓는다.
    final uri = Uri.base;
    _token = uri.queryParameters['token'];

    _loadPolicy();
  }

  Future<void> _loadPolicy() async {
    setState(() {
      _isPolicyLoading = true;
    });
    try {
      final policy = await AuthProxyService.fetchPasswordPolicy();
      if (mounted) {
        setState(() {
          _policy = policy;
        });
      }
    } catch (_) {
      // 실패해도 기본 검증 로직 사용
    } finally {
      if (mounted) {
        setState(() {
          _isPolicyLoading = false;
        });
      }
    }
  }

  Future<void> _handlePasswordReset() async {
    if (_formKey.currentState?.validate() != true) return;
    if ((_loginId == null || _loginId!.isEmpty) &&
        (_token == null || _token!.isEmpty)) {
      _showError(tr('msg.userfront.reset.invalid_link'));
      return;
    }

    setState(() => _isLoading = true);

    try {
      await AuthProxyService.completePasswordReset(
        loginId: _loginId,
        token: _token,
        newPassword: _passwordController.text,
      );

      if (mounted) {
        ToastService.success(tr('msg.userfront.reset.success'));
        context.go(buildLocalizedSigninPath(Uri.base));
      }
    } catch (e) {
      if (mounted) {
        _showError(
          tr(
            'msg.userfront.reset.error.generic',
            params: {'error': e.toString()},
          ),
        );
      }
    } finally {
      if (mounted) {
        setState(() => _isLoading = false);
      }
    }
  }

  void _showError(String message) {
    ToastService.error(message);
  }

  String _buildPolicyDescription() {
    if (_isPolicyLoading) {
      return tr('msg.userfront.reset.policy_loading');
    }
    final minLength = (_policy?['minLength'] as int?) ?? 12;
    final minTypes = (_policy?['minCharacterTypes'] as int?) ?? 0;
    final requiresLower = _policy?['lowercase'] ?? true;
    final requiresUpper = _policy?['uppercase'] ?? false;
    final requiresNumber = _policy?['number'] ?? true;
    final requiresSymbol = _policy?['nonAlphanumeric'] ?? true;

    final parts = <String>[
      tr(
        'msg.userfront.reset.policy.min_length',
        params: {'count': '$minLength'},
      ),
    ];
    if (minTypes > 0) {
      parts.add(
        tr(
          'msg.userfront.reset.policy.min_types',
          params: {'count': '$minTypes'},
        ),
      );
    }
    if (requiresLower) {
      parts.add(tr('msg.userfront.reset.policy.lowercase'));
    }
    if (requiresUpper) {
      parts.add(tr('msg.userfront.reset.policy.uppercase'));
    }
    if (requiresNumber) {
      parts.add(tr('msg.userfront.reset.policy.number'));
    }
    if (requiresSymbol) {
      parts.add(tr('msg.userfront.reset.policy.symbol'));
    }

    return parts.join(", ");
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(tr('ui.userfront.reset.title')),
        centerTitle: true,
      ),
      body: Center(
        child: Container(
          constraints: const BoxConstraints(maxWidth: 400),
          padding: const EdgeInsets.all(24),
          child:
              (_loginId == null || _loginId!.isEmpty) &&
                  (_token == null || _token!.isEmpty)
              ? _buildInvalidTokenView()
              : Form(
                  key: _formKey,
                  child: Column(
                    mainAxisAlignment: MainAxisAlignment.center,
                    crossAxisAlignment: CrossAxisAlignment.stretch,
                    children: [
                      Text(
                        tr('ui.userfront.reset.subtitle'),
                        style: const TextStyle(
                          fontSize: 28,
                          fontWeight: FontWeight.bold,
                        ),
                        textAlign: TextAlign.center,
                      ),
                      const SizedBox(height: 16),
                      Text(
                        _buildPolicyDescription(),
                        textAlign: TextAlign.center,
                        style: const TextStyle(color: Colors.grey),
                      ),
                      const SizedBox(height: 40),
                      TextFormField(
                        key: const ValueKey('reset_password_new_input'),
                        controller: _passwordController,
                        obscureText: _isPasswordObscured,
                        decoration: InputDecoration(
                          labelText: tr('ui.userfront.reset.new_password'),
                          border: const OutlineInputBorder(),
                          prefixIcon: const Icon(Icons.lock_outline),
                          suffixIcon: IconButton(
                            icon: Icon(
                              _isPasswordObscured
                                  ? Icons.visibility_off
                                  : Icons.visibility,
                            ),
                            onPressed: () {
                              setState(() {
                                _isPasswordObscured = !_isPasswordObscured;
                              });
                            },
                          ),
                        ),
                        validator: (value) {
                          final val = value ?? "";
                          if (val.isEmpty) {
                            return tr(
                              'msg.userfront.reset.error.empty_password',
                            );
                          }
                          final minLength =
                              (_policy?['minLength'] as int?) ?? 12;
                          if (val.length < minLength) {
                            return tr(
                              'msg.userfront.reset.error.min_length',
                              params: {'count': '$minLength'},
                            );
                          }
                          final hasLower = RegExp(r'[a-z]').hasMatch(val);
                          final hasUpper = RegExp(r'[A-Z]').hasMatch(val);
                          final hasNumber = RegExp(r'[0-9]').hasMatch(val);
                          final hasSymbol = RegExp(r'[\W_]').hasMatch(val);
                          int typeCount = 0;
                          if (hasLower) typeCount++;
                          if (hasUpper) typeCount++;
                          if (hasNumber) typeCount++;
                          if (hasSymbol) typeCount++;

                          final minTypes =
                              (_policy?['minCharacterTypes'] as int?) ?? 0;
                          if (minTypes > 0 && typeCount < minTypes) {
                            return tr(
                              'msg.userfront.reset.error.min_types',
                              params: {'count': '$minTypes'},
                            );
                          }

                          if ((_policy?['lowercase'] ?? true) && !hasLower) {
                            return tr('msg.userfront.reset.error.lowercase');
                          }
                          if ((_policy?['uppercase'] ?? false) && !hasUpper) {
                            return tr('msg.userfront.reset.error.uppercase');
                          }
                          if ((_policy?['number'] ?? true) && !hasNumber) {
                            return tr('msg.userfront.reset.error.number');
                          }
                          if ((_policy?['nonAlphanumeric'] ?? true) &&
                              !hasSymbol) {
                            return tr('msg.userfront.reset.error.symbol');
                          }
                          return null;
                        },
                      ),
                      const SizedBox(height: 16),
                      TextFormField(
                        key: const ValueKey('reset_password_confirm_input'),
                        controller: _confirmPasswordController,
                        obscureText: _isConfirmPasswordObscured,
                        decoration: InputDecoration(
                          labelText: tr('ui.userfront.reset.confirm_password'),
                          border: const OutlineInputBorder(),
                          prefixIcon: const Icon(Icons.lock_outline),
                          suffixIcon: IconButton(
                            icon: Icon(
                              _isConfirmPasswordObscured
                                  ? Icons.visibility_off
                                  : Icons.visibility,
                            ),
                            onPressed: () {
                              setState(() {
                                _isConfirmPasswordObscured =
                                    !_isConfirmPasswordObscured;
                              });
                            },
                          ),
                        ),
                        validator: (value) {
                          if (value != _passwordController.text) {
                            return tr('msg.userfront.reset.error.mismatch');
                          }
                          return null;
                        },
                      ),
                      const SizedBox(height: 24),
                      FilledButton(
                        key: const ValueKey('reset_password_submit_button'),
                        onPressed: _isLoading ? null : _handlePasswordReset,
                        style: FilledButton.styleFrom(
                          minimumSize: const Size.fromHeight(50),
                        ),
                        child: _isLoading
                            ? const SizedBox(
                                height: 20,
                                width: 20,
                                child: CircularProgressIndicator(
                                  strokeWidth: 2,
                                  color: Colors.white,
                                ),
                              )
                            : Text(tr('ui.userfront.reset.submit')),
                      ),
                    ],
                  ),
                ),
        ),
      ),
    );
  }

  Widget _buildInvalidTokenView() {
    return Center(
      child: Column(
        mainAxisAlignment: MainAxisAlignment.center,
        children: [
          const Icon(Icons.error_outline, color: Colors.red, size: 60),
          const SizedBox(height: 16),
          Text(
            tr('msg.userfront.reset.invalid_title'),
            style: const TextStyle(fontSize: 18, fontWeight: FontWeight.bold),
            textAlign: TextAlign.center,
          ),
          const SizedBox(height: 8),
          Text(
            tr('msg.userfront.reset.invalid_body'),
            textAlign: TextAlign.center,
          ),
        ],
      ),
    );
  }
}