import 'package:flutter/foundation.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:shared_preferences/shared_preferences.dart';

const _kAccessToken = 'access_token';
const _kRefreshToken = 'refresh_token';
const _kUsername = 'username';
const _kRealName = 'real_name';
const _kShopNo = 'shop_no';
const _kShopId = 'shop_id';
const _kRole = 'role';

class AuthUser {
  final String accessToken;
  final String refreshToken;
  final String username;
  final String realName;
  final String shopNo;
  final int shopId;
  final String role;

  const AuthUser({
    required this.accessToken,
    required this.refreshToken,
    required this.username,
    required this.realName,
    required this.shopNo,
    required this.shopId,
    this.role = 'operator',
  });

  // Kept for ApiClient compatibility
  String get token => accessToken;
}

class AuthState {
  final AuthUser? user;
  final bool initialized;
  const AuthState({this.user, this.initialized = false});
  bool get isLoggedIn => user != null;
}

class AuthNotifier extends StateNotifier<AuthState> {
  AuthNotifier() : super(const AuthState());

  /// Called at app startup to restore persisted session.
  Future<void> restore() async {
    try {
      final prefs = await SharedPreferences.getInstance();
      final accessToken = prefs.getString(_kAccessToken);
      final refreshToken = prefs.getString(_kRefreshToken);
      final username = prefs.getString(_kUsername);
      final realName = prefs.getString(_kRealName);
      final shopNo = prefs.getString(_kShopNo);
      final shopIdStr = prefs.getString(_kShopId);

      final role = prefs.getString(_kRole);
      if (accessToken != null && refreshToken != null && username != null) {
        state = AuthState(
          initialized: true,
          user: AuthUser(
            accessToken: accessToken,
            refreshToken: refreshToken,
            username: username,
            realName: realName ?? username,
            shopNo: shopNo ?? '',
            shopId: int.tryParse(shopIdStr ?? '') ?? 0,
            role: role ?? 'operator',
          ),
        );
        return;
      }
    } catch (_) {
      // Storage unavailable — fall through to logged-out state
    }
    state = const AuthState(initialized: true);
  }

  Future<void> login(AuthUser user) async {
    debugPrint('[Auth] login() called, username=${user.username} shopId=${user.shopId}');
    final prefs = await SharedPreferences.getInstance();
    await prefs.setString(_kAccessToken, user.accessToken);
    await prefs.setString(_kRefreshToken, user.refreshToken);
    await prefs.setString(_kUsername, user.username);
    await prefs.setString(_kRealName, user.realName);
    await prefs.setString(_kShopNo, user.shopNo);
    await prefs.setString(_kShopId, user.shopId.toString());
    await prefs.setString(_kRole, user.role);
    debugPrint('[Auth] login() setting state, token prefix: ${user.accessToken.substring(0, user.accessToken.length.clamp(0, 20))}...');
    state = AuthState(initialized: true, user: user);
    debugPrint('[Auth] login() state set, isLoggedIn=${state.isLoggedIn}');
  }

  void updateAccessToken(String newToken) {
    if (state.user == null) return;
    SharedPreferences.getInstance()
        .then((prefs) => prefs.setString(_kAccessToken, newToken));
    state = AuthState(
      initialized: true,
      user: AuthUser(
        accessToken: newToken,
        refreshToken: state.user!.refreshToken,
        username: state.user!.username,
        realName: state.user!.realName,
        shopNo: state.user!.shopNo,
        shopId: state.user!.shopId,
        role: state.user!.role,
      ),
    );
  }

  Future<void> logout() async {
    debugPrint('[Auth] logout() called! stack: ${StackTrace.current}');
    final prefs = await SharedPreferences.getInstance();
    await prefs.remove(_kAccessToken);
    await prefs.remove(_kRefreshToken);
    await prefs.remove(_kUsername);
    await prefs.remove(_kRealName);
    await prefs.remove(_kShopNo);
    await prefs.remove(_kShopId);
    await prefs.remove(_kRole);
    state = const AuthState(initialized: true);
  }
}

final authStateProvider = StateNotifierProvider<AuthNotifier, AuthState>(
  (ref) => AuthNotifier(),
);