import 'package:flutter/material.dart';
import 'package:sales_chat/models/user.dart';
import 'package:sales_chat/services/api_service.dart';

class AuthProvider with ChangeNotifier {
  final ApiService _apiService;

  User? _user;
  bool _isLoading = false;
  String? _error;

  AuthProvider(this._apiService);

  User? get user => _user;
  bool get isLoading => _isLoading;
  String? get error => _error;
  bool get isLoggedIn => _user != null;
  Future<bool> get isAuthenticated => _apiService.isAuthenticated;

  /// 使用邮箱/用户名和密码登录。
  /// 至少提供其中一个 [email] 或 [username]。
  Future<bool> login({
    String? email,
    String? username,
    required String password,
  }) async {
    _isLoading = true;
    _error = null;
    notifyListeners();

    try {
      final response = await _apiService.login(
        email: email,
        username: username,
        password: password,
      );
      _user = response.user;
      _isLoading = false;
      notifyListeners();
      return true;
    } catch (e) {
      _error = _parseError(e);
      _isLoading = false;
      notifyListeners();
      return false;
    }
  }

  /// 以访客身份登录（临时用户）。
  Future<bool> loginAsGuest({required String nickname}) async {
    _isLoading = true;
    _error = null;
    notifyListeners();

    try {
      final response = await _apiService.createTemporaryUser(nickname: nickname);
      _user = response.user;
      _isLoading = false;
      notifyListeners();
      return true;
    } catch (e) {
      _error = _parseError(e);
      _isLoading = false;
      notifyListeners();
      return false;
    }
  }

  /// 注册新用户。
  Future<bool> register({
    String? username,
    String? email,
    String? nickname,
    required String password,
  }) async {
    _isLoading = true;
    _error = null;
    notifyListeners();

    try {
      final response = await _apiService.register(
        username: username,
        email: email,
        nickname: nickname,
        password: password,
      );
      _user = response.user;
      _isLoading = false;
      notifyListeners();
      return true;
    } catch (e) {
      _error = _parseRegisterError(e);
      _isLoading = false;
      notifyListeners();
      return false;
    }
  }

  Future<void> logout() async {
    _isLoading = true;
    notifyListeners();

    try {
      await _apiService.logout();
    } finally {
      _user = null;
      _isLoading = false;
      notifyListeners();
    }
  }

  Future<void> loadUser() async {
    if (!await _apiService.isAuthenticated) return;

    _isLoading = true;
    notifyListeners();

    try {
      _user = await _apiService.getCurrentUser();
    } catch (e) {
      _user = null;
    } finally {
      _isLoading = false;
      notifyListeners();
    }
  }

  void clearError() {
    _error = null;
    notifyListeners();
  }

  String _parseError(dynamic e) {
    final errStr = e.toString();
    if (errStr.contains('401')) {
      return 'Email/username or password incorrect';
    } else if (errStr.contains('422') || errStr.contains('password')) {
      return 'Email/username or password incorrect';
    } else if (errStr.contains('timeout')) {
      return 'Network timeout, please retry';
    } else if (errStr.contains('SocketException')) {
      return 'Network connection failed';
    } else if (errStr.contains('banned')) {
      return 'Account has been banned';
    }
    return 'Login failed, please retry';
  }

  String _parseRegisterError(dynamic e) {
    final errorStr = e.toString();
    if (errorStr.contains('exist')) {
      return 'Username or email already exists';
    } else if (errorStr.contains('empty')) {
      return 'Username or email is required';
    } else if (errorStr.contains('timeout')) {
      return 'Network timeout, please retry';
    } else if (errorStr.contains('SocketException')) {
      return 'Network connection failed';
    } else if (errorStr.contains('not allowed')) {
      return 'Server does not allow new user registration';
    }
    return 'Registration failed, please retry';
  }
}