lobby-systems/src/main/java/id/dartokloning/lobbysystems/PlayerDataStore.java

package id.dartokloning.lobbysystems;

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.google.gson.JsonElement;
import com.google.gson.JsonObject;
import com.google.gson.JsonParser;

import java.io.Reader;
import java.io.Writer;
import java.lang.reflect.Type;
import java.nio.file.Files;

/**
 * Shared persistent player database. Auth and last-position data intentionally
 * live in one file while remaining separate logical sections, so either
 * subsystem can update its own data without overwriting the other.
 */
public final class PlayerDataStore {
    private static final Gson GSON = new GsonBuilder().setPrettyPrinting().create();
    private static final Object LOCK = new Object();
    private static final String AUTH = "auth";
    private static final String POSITIONS = "positions";

    private PlayerDataStore() {}

    public static <T> T loadAuth(Type type, T fallback) {
        return loadSection(AUTH, type, fallback);
    }

    public static <T> T loadPositions(Type type, T fallback) {
        return loadSection(POSITIONS, type, fallback);
    }

    public static void saveAuth(Object value, Type type) {
        saveSection(AUTH, value, type);
    }

    public static void savePositions(Object value, Type type) {
        saveSection(POSITIONS, value, type);
    }

    private static <T> T loadSection(String name, Type type, T fallback) {
        synchronized (LOCK) {
            try {
                JsonObject root = readRoot();
                JsonElement section = root.get(name);
                if (section == null || section.isJsonNull()) return fallback;
                T loaded = GSON.fromJson(section, type);
                return loaded == null ? fallback : loaded;
            } catch (Exception e) {
                LobbySystemsMod.LOGGER.error("Failed to load '{}' from {}", name, ConfigPaths.PLAYER, e);
                return fallback;
            }
        }
    }

    private static void saveSection(String name, Object value, Type type) {
        synchronized (LOCK) {
            try {
                JsonObject root = readRoot();
                root.add(name, GSON.toJsonTree(value, type));
                Files.createDirectories(ConfigPaths.PLAYER.getParent());
                try (Writer writer = Files.newBufferedWriter(ConfigPaths.PLAYER)) {
                    GSON.toJson(root, writer);
                }
            } catch (Exception e) {
                LobbySystemsMod.LOGGER.error("Failed to save '{}' to {}", name, ConfigPaths.PLAYER, e);
            }
        }
    }

    private static JsonObject readRoot() throws Exception {
        if (!Files.exists(ConfigPaths.PLAYER)) return new JsonObject();
        try (Reader reader = Files.newBufferedReader(ConfigPaths.PLAYER)) {
            JsonElement parsed = JsonParser.parseReader(reader);
            if (parsed == null || parsed.isJsonNull()) return new JsonObject();
            if (!parsed.isJsonObject()) throw new IllegalArgumentException("player.json root must be a JSON object");
            return parsed.getAsJsonObject();
        }
    }
}