"""One managed temporary Minecraft server at a time on this host."""
from contextlib import contextmanager
import fcntl
from pathlib import Path
import tempfile


@contextmanager
def server_test_lock():
    with (Path(tempfile.gettempdir()) / "rivencraft-server-tests.lock").open("a") as lock:
        try:
            fcntl.flock(lock, fcntl.LOCK_EX | fcntl.LOCK_NB)
        except BlockingIOError:
            raise SystemExit("Another Rivencraft server test is active; finish it before starting this one")
        try:
            yield
        finally:
            fcntl.flock(lock, fcntl.LOCK_UN)