import 'package:firebase_auth/firebase_auth.dart' as fb;
import 'package:flutter/foundation.dart' show kIsWeb;
import 'package:google_sign_in/google_sign_in.dart';

import '../../shared/models/user.dart';
import '../api/api_client.dart';
import 'secure_storage.dart';

class AuthService {
  final fb.FirebaseAuth _firebaseAuth;
  final ApiClient _apiClient;
  final SecureStorageService _storage;

  AuthService({
    required fb.FirebaseAuth firebaseAuth,
    required ApiClient apiClient,
    required SecureStorageService storage,
  })  : _firebaseAuth = firebaseAuth,
        _apiClient = apiClient,
        _storage = storage;

  Future<User> signInWithGoogle() async {
    if (kIsWeb) {
      // На вебе используем signInWithPopup — открывает Google popup в браузере
      final provider = fb.GoogleAuthProvider();
      final userCredential = await _firebaseAuth.signInWithPopup(provider);
      return _authenticateWithBackend(userCredential);
    } else {
      // На мобильных используем google_sign_in
      final googleUser = await GoogleSignIn().signIn();
      if (googleUser == null) {
        throw Exception('Google sign-in cancelled');
      }
      final googleAuth = await googleUser.authentication;
      final credential = fb.GoogleAuthProvider.credential(
        accessToken: googleAuth.accessToken,
        idToken: googleAuth.idToken,
      );
      final userCredential =
          await _firebaseAuth.signInWithCredential(credential);
      return _authenticateWithBackend(userCredential);
    }
  }

  Future<User> signInWithEmail(String email, String password) async {
    final userCredential = await _firebaseAuth.signInWithEmailAndPassword(
      email: email,
      password: password,
    );
    return _authenticateWithBackend(userCredential);
  }

  Future<User> registerWithEmail(
      String email, String password, String name) async {
    final userCredential = await _firebaseAuth.createUserWithEmailAndPassword(
      email: email,
      password: password,
    );
    await userCredential.user!.updateDisplayName(name);
    return _authenticateWithBackend(userCredential);
  }

  Future<User> _authenticateWithBackend(fb.UserCredential credential) async {
    final idToken = await credential.user!.getIdToken();

    final response = await _apiClient.post('/auth/login', data: {
      'firebase_token': idToken,
    });

    await _storage.saveTokens(
      accessToken: response['access_token'],
      refreshToken: response['refresh_token'],
    );

    return User.fromJson(response['user']);
  }

  Future<void> signOut() async {
    try {
      await _apiClient.post('/auth/logout');
    } catch (_) {
      // Don't block logout on backend failure
    }
    await _firebaseAuth.signOut();
    await _storage.clearTokens();
  }

  Future<bool> isAuthenticated() async {
    final token = await _storage.getAccessToken();
    return token != null;
  }
}