"""
全局同步锁与同步模式标记
同步期间禁止所有写操作，前端显示同步遮罩
"""
import threading

_sync_lock = threading.Lock()
_sync_in_progress = False
_sync_mode = threading.local()


def acquire_sync_lock() -> bool:
    """非阻塞获取同步锁，成功返回 True"""
    acquired = _sync_lock.acquire(blocking=False)
    if acquired:
        global _sync_in_progress
        _sync_in_progress = True
        _sync_mode.active = True
    return acquired


def release_sync_lock():
    """释放同步锁"""
    global _sync_in_progress
    _sync_in_progress = False
    _sync_mode.active = False
    _sync_lock.release()


def is_syncing() -> bool:
    """检查是否正在同步"""
    return _sync_in_progress


def is_sync_mode() -> bool:
    """检查当前线程是否在同步模式中（跳过 sync_version 自增）"""
    return getattr(_sync_mode, 'active', False)