import logging
import threading
from typing import Union

import gevent.threading


class UnLock(object):
    """
    The idea is to use this class within a context manager to release a lock temporarily but then acquire it again.
    Example:
        lock = gevent.threading.Lock()
        with lock:
            logging.info('Websocket request 10 received')
            with UnLock(lock):
                sleep(10.)  # this part does not need the resource to be locked
            logging.info('Websocket request 10 finished')
    """

    def __init__(self, lock: Union[gevent.threading.Lock, threading.Lock], require_taken: bool = True, verbose=False):
        self.lock = lock
        self.require_taken = require_taken
        self.verbose = verbose

    def __enter__(self):
        if self.require_taken and not self.lock.locked():
            raise RuntimeError('Lock not taken')
        self.lock.release()
        if self.verbose:
            logging.info('Unlocked')

    def __exit__(self, exc_type, exc_val, exc_tb):
        self.lock.acquire()
        if self.verbose:
            logging.info('Locked again.')