import 'dart:async';

import 'package:freezed_annotation/freezed_annotation.dart';
import 'package:riverpod_annotation/riverpod_annotation.dart';
import 'package:sunny_mochi/core/error/exception_mapper.dart';
import 'package:sunny_mochi/features/auth/auth_providers.dart';
import 'package:sunny_mochi/features/auth/domain/entities/user_entity.dart';
import 'package:sunny_mochi/features/auth/presentation/notifiers/auth_status_provider.dart';

part 'auth_notifier.freezed.dart';
part 'auth_notifier.g.dart';

@freezed
sealed class AuthState with _$AuthState {
  const factory AuthState.initial() = AuthInitial;
  const factory AuthState.loading() = AuthLoading;
  const factory AuthState.authenticated(UserEntity user) = AuthAuthenticated;
  const factory AuthState.unauthenticated() = AuthUnauthenticated;
  const factory AuthState.error(String message) = AuthError;
}

@riverpod
class AuthNotifier extends _$AuthNotifier {
  static const _mapper = ExceptionMapper();

  // generation 计数：防止旧 async 回调覆盖最新登录态
  int _generation = 0;

  @override
  AuthState build() {
    final gen = ++_generation;
    unawaited(_checkAuth(gen));
    return const AuthState.initial();
  }

  Future<void> _checkAuth(int gen) async {
    final user = await ref.read(authRepositoryProvider).getCurrentUser();
    if (_generation != gen) return;
    if (user != null) {
      state = AuthState.authenticated(user);
      ref.read(authStatusProvider).markLoggedIn();
      unawaited(refreshUserInfo());
    } else {
      state = const AuthState.unauthenticated();
      ref.read(authStatusProvider).markLoggedOut();
    }
  }

  Future<void> loginWithPhone(String phone, String code) async {
    _generation++;
    state = const AuthState.loading();
    try {
      final user = await ref
          .read(authRepositoryProvider)
          .loginWithPhone(phone: phone, code: code);
      state = AuthState.authenticated(user);
      ref.read(authStatusProvider).markLoggedIn();
      unawaited(refreshUserInfo());
    } on Object catch (e, st) {
      final failure = _mapper.fromUnknown(e, st);
      state = AuthState.error(failure.message);
    }
  }

  Future<void> loginWithPassword(String phone, String password) async {
    _generation++;
    state = const AuthState.loading();
    try {
      final user = await ref
          .read(authRepositoryProvider)
          .loginWithPassword(phone: phone, password: password);
      state = AuthState.authenticated(user);
      ref.read(authStatusProvider).markLoggedIn();
      unawaited(refreshUserInfo());
    } on Object catch (e, st) {
      final failure = _mapper.fromUnknown(e, st);
      state = AuthState.error(failure.message);
    }
  }

  Future<void> logout() async {
    _generation++;
    state = const AuthState.unauthenticated();
    ref.read(authStatusProvider).markLoggedOut();
    unawaited(ref.read(authRepositoryProvider).logout());
  }

  /// 发送短信验证码。返回 dev/test 环境后端回显的验证码（release 为 null），供 UI 自动填入。
  Future<String?> sendSmsCode(String phone) async {
    try {
      return await ref.read(authRepositoryProvider).sendSmsCode(phone);
    } on Object catch (e, st) {
      throw _mapper.fromUnknown(e, st);
    }
  }

  Future<void> refreshUserInfo() async {
    final current = state;
    if (current is! AuthAuthenticated) return;
    final gen = _generation;
    try {
      final fresh = await ref.read(authRepositoryProvider).fetchUserProfile();
      if (_generation != gen) return;
      state = AuthState.authenticated(
        fresh.copyWith(
          token: current.user.token,
          userId: fresh.userId ?? current.user.userId,
        ),
      );
    } on Object {
      // profile 拉取失败不应改变登录状态
    }
  }
}