"""Coordinate queue file reads and replacement across Windows processes/threads."""

from functools import lru_cache
from pathlib import Path

from filelock import FileLock


@lru_cache(maxsize=128)
def _directory_lock(directory: Path) -> FileLock:
    # One small OS-backed lock per queue directory, not one leftover file per
    # task. FileLock releases the OS lock when its process exits.
    return FileLock(directory / ".artemis-queue-io.lock", timeout=3)


def queue_file_lock(path: Path):
    """Hold only during file I/O, never across device operations or retry sleeps."""
    return _directory_lock(path.parent.resolve()).acquire(poll_interval=0.005)


def read_queue_text(path: Path) -> str:
    with queue_file_lock(path):
        return path.read_text(encoding="utf-8")