convert_world.py

import nbt
import os
import requests
import shutil
import uuid

uuids = {}

for file in os.listdir("world/playerdata"):
    if file.endswith(".dat"):
        nbtfile = nbt.nbt.NBTFile(os.path.join("world/playerdata", file), "rb")
        uuids[file.split(".")[0]] = nbtfile["bukkit"]["lastKnownName"].value

    if file.endswith(".dat_old"):
        os.remove(os.path.join("world/playerdata", file))

for offline_uuid, player_name in uuids.items():
    # check if player name is premium
    r = requests.get("https://api.mojang.com/users/profiles/minecraft/" + player_name)
    r.raise_for_status()

    try:
        data = r.json()
    except:
        continue

    premium_uuid = uuid.UUID(data["id"])
    print(f"Converting offline UUID for player {player_name} with UUID {premium_uuid}")
    
    shutil.move(f"world/playerdata/{offline_uuid}.dat", f"world/playerdata/{premium_uuid}.dat")
    shutil.move(f"world/stats/{offline_uuid}.json", f"world/stats/{premium_uuid}.json")
    shutil.move(f"world/advancements/{offline_uuid}.json", f"world/advancements/{premium_uuid}.json")