Local Storage Service with Enum Keys

local_storage_service.dart

import 'dart:convert';

import 'package:get_storage/get_storage.dart';
import 'package:quran_app/screens/settings/bloc/settings_bloc.dart';

/// Read custom class from local storage
final SettingsState settings =
    LocalStorageKey.settingsObject.readObject(SettingsState.empty());

/// Read email from local storage
final String? email = LocalStorageKey.email.read();

enum LocalStorageKey {
  settingsObject,
  email,
}

extension LocalStorageExtension on LocalStorageKey {
  read() => LocalStorageService.instance.read(this);
  remove() => LocalStorageService.instance.remove(this);
  write(value) => LocalStorageService.instance.write(this, value);

  T readObject<T extends Encodable>(T instance) => LocalStorageService.instance
      .readObject<T>(this, defaultInstance: instance);

  writeObject<T extends Codable>(T object) =>
      LocalStorageService.instance.writeObject(this, object);
}

class LocalStorageService {
  LocalStorageService._();
  static final instance = LocalStorageService._();

  late GetStorage _storage;

  init() async {
    await GetStorage.init();
    _storage = GetStorage();
  }

  read(LocalStorageKey key) {
    return _storage.read(key.name);
  }

  remove(LocalStorageKey key) {
    return _storage.remove(key.name);
  }

  write(LocalStorageKey key, value) {
    return _storage.write(key.name, value);
  }

  clearAll() {
    _storage.erase();
  }

  T readObject<T extends Encodable>(LocalStorageKey key,
      {required T defaultInstance}) {
    final value = _storage.read(key.name);
    if (value == null) {
      return defaultInstance;
    }
    return defaultInstance.fromMap(jsonDecode(value));
  }

  writeObject(LocalStorageKey key, Codable object) {
    return _storage.write(key.name, jsonEncode(object.toMap()));
  }
}

abstract class Codable {
  Object toMap();
}

abstract class Encodable<T> {
  T fromMap(Map<String, dynamic> map);
}