frosty/lib/stores/auth_store.dart

import 'package:frosty/api/twitch_api.dart';
import 'package:mobx/mobx.dart';
import 'package:flutter/foundation.dart';
import 'package:frosty/constants.dart';
import 'package:frosty/models/user.dart';
import 'package:flutter_secure_storage/flutter_secure_storage.dart';
import 'package:flutter_web_auth/flutter_web_auth.dart';

part 'auth_store.g.dart';

class AuthStore = _AuthBase with _$AuthStore;

abstract class _AuthBase with Store {
  // Secure storage to store tokens
  final _storage = const FlutterSecureStorage();

  // The current token
  @observable
  String? _token;
  String? get token => _token;

  // Whether the user is logged in or not
  @observable
  var _isLoggedIn = false;
  bool get isLoggedIn => _isLoggedIn;

  // Whether the token is valid or not
  @observable
  var _tokenIsValid = false;

  // The current user's info
  @observable
  UserTwitch? _user;
  UserTwitch? get user => _user;

  // Authentication headers for Twitch API requests
  @computed
  Map<String, String> get headersTwitch => {'Authorization': 'Bearer $_token', 'Client-Id': clientId};

  /// Initialize by retrieving a token if it does not already exist.
  @action
  Future<void> init() async {
    // Read and set the currently stored user token, if any.
    _token = await _storage.read(key: 'USER_TOKEN');

    // If the token does not exist, get the default token.
    // Otherwise, log in and get the user info.
    if (_token == null) {
      // Retrieve the currently stored default token if it exists
      _token = await _storage.read(key: 'DEFAULT_TOKEN');
      // If the token does not exist, get a new token and store it
      if (_token == null) {
        _token = await Twitch.getDefaultToken();
        await _storage.write(key: 'DEFAULT_TOKEN', value: _token);
      }
    } else {
      _isLoggedIn = true;
      _user = await Twitch.getUserInfo(headers: headersTwitch);
    }

    // Validate the token
    _tokenIsValid = await Twitch.validateToken(token: _token!);

    // If the token is invalid, logout
    if (!_tokenIsValid) {
      logout();
      return;
    }

    debugPrint('Token is valid: $_tokenIsValid');
    debugPrint('Created auth provider');
  }

  /// Initiates the OAuth sign-in process and updates fields accordingly upon successful login
  @action
  Future<void> login() async {
    // Create the OAuth sign-in URI
    final loginUrl = Uri(
      scheme: 'https',
      host: 'id.twitch.tv',
      path: '/oauth2/authorize',
      queryParameters: {
        'client_id': clientId,
        'redirect_uri': 'auth://',
        'response_type': 'token',
        'scope': 'chat:read chat:edit user:read:follows',
      },
    );

    try {
      // Retrieve the OAuth redirect URI
      final result = await FlutterWebAuth.authenticate(url: loginUrl.toString(), callbackUrlScheme: 'auth', preferEphemeral: true);

      // Parse the user token from the redirect URI fragment
      final fragment = Uri.parse(result).fragment;
      _token = fragment.substring(fragment.indexOf('=') + 1, fragment.indexOf('&'));

      // Store the user token
      await _storage.write(key: 'USER_TOKEN', value: _token);

      // Retrieve the user info and set it
      _user = await Twitch.getUserInfo(headers: headersTwitch);

      // Set the login status to logged in
      _isLoggedIn = true;
    } catch (error) {
      debugPrint('Login failed due to $error');
    }
  }

  // Logs out the current user and updates fields accordingly
  @action
  Future<void> logout() async {
    // If the default token already exists, set it. Otherwise, get a new default token.
    _token = await _storage.read(key: 'DEFAULT_TOKEN') ?? await Twitch.getDefaultToken();

    // Clear the user info
    _user = null;

    // Set the login status to logged out
    _isLoggedIn = false;
    debugPrint('Successfully logged out');
  }
}