Updated UserConfig

package org.example;

import ninja.leaping.configurate.commented.CommentedConfigurationNode;
import ninja.leaping.configurate.loader.ConfigurationLoader;
import org.spongepowered.api.Sponge;
import org.spongepowered.api.profile.GameProfile;
import org.spongepowered.api.service.user.UserStorageService;

import java.io.File;
import java.util.*;
import java.util.function.Predicate;

public class UserConfig extends Config {

    private static final String DISCORD_ID_NODE = "discordid";
    private static final String NICKNAME_NODE = "nickname";
    private static final String USER_CODE_NODE = "code";
    private static final String CLASSES_NODE = "classes";

    public UserConfig(ConfigurationLoader<CommentedConfigurationNode> loader, CommentedConfigurationNode root){
        super(loader, root);
    }

    public UserConfig(File file) {
        super(file);
    }

    public boolean isUserRegistered(UUID uuid){
        return this.<Boolean>get(n -> n.isVirtual(), "users", uuid.toString());
    }

    public Optional<GameProfile> getProfileByDiscord(String discordId){
        return getByStringNode(discordId, DISCORD_ID_NODE);
    }

    public Optional<GameProfile> getProfileByNickname(String nick){
        return getByStringNode(nick, NICKNAME_NODE);
    }

    public List<String> getUserClasses(UUID uuid){
        return this.getList(n -> n.getString(), "users", uuid.toString(), CLASSES_NODE);
    }

    public Optional<String> getUserCode(UUID uuid){
        return Optional.ofNullable(this.getString("users", uuid.toString(), USER_CODE_NODE));
    }

    public void registerUser(UUID uuid, String nick, String discord, String code, String... classes){
        set(nick, "users", uuid.toString(), NICKNAME_NODE);
        set(discord, "users", uuid.toString(), DISCORD_ID_NODE);
        set(code, "users", uuid.toString(), USER_CODE_NODE);
        set(Arrays.asList(classes), "users", uuid.toString(), CLASSES_NODE);
    }

    public void registerClass(UUID uuid, String className){
        List<String> list = new ArrayList<>(getUserClasses(uuid));
        list.add(className);
        set(list, "users", uuid.toString(), CLASSES_NODE);
    }

    public void deleteClass(UUID uuid, String className){
        List<String> list = new ArrayList<>(getUserClasses(uuid));
        list.remove(className);
        set(list, "users", uuid.toString(), CLASSES_NODE);
    }

    public void deleteUser(UUID uuid){
        remove("users", uuid.toString());
    }

    public boolean hasUserClass(UUID uuid, String className){
        return getUserClasses(uuid).stream().anyMatch(s -> s.equalsIgnoreCase(className));
    }

    private Optional<GameProfile> getByStringNode(String idToCheck, String node){
        return getGameProfiles(gp -> {
            String id = this.getString("users", gp.getUniqueId().toString(), node);
            if(id == null){
                return false;
            }
            if(id.equalsIgnoreCase(idToCheck)){
                return true;
            }
            return false;
        });
    }

    private Optional<GameProfile> getGameProfiles(Predicate<GameProfile> filterTo){
        UserStorageService userStorageService = Sponge.getServiceManager().getRegistration(UserStorageService.class).get().getProvider();
        return userStorageService.getAll().stream().filter(filterTo).findFirst();
    }
}