import { LocalStorageService } from '../storage';
import { UsersPreferences } from '../../models/user-preference/users-preferences';
/**
 * Service for storing and retrieving user preferences data from local storage.
 */
export declare class UserPreferencesStorageService extends LocalStorageService {
    /**
     * Namespace used for user-related local storage entries.
     */
    readonly NAMESPACE = "userPreferences";
    /**
     * Local storage key used for persisted preferences of users.
     */
    private readonly USER_PREFERENCES;
    /**
     * Stores a value in local storage.
     *
     * @param key - The storage key.
     * @param value - The value to store.
     */
    set(key: string, value: string): void;
    /**
     * Stores the preferences of all known users.
     *
     * @param userPreferences - The user preferences collection to persist.
     */
    setUsersPreferences(userPreferences: UsersPreferences): void;
    /**
     * Returns the persisted preferences of all known users.
     *
     * If no preferences are stored, an empty preferences collection is returned.
     *
     * @returns The stored user preferences collection.
     */
    getPreferences(): UsersPreferences;
}