import signal

from threading import Thread, Event
from queue import Queue


def prepend_signal(sig, func):
    handler = signal.getsignal(sig)

    def wrapper(*args, **kwargs):
        func(*args, **kwargs)
        handler(*args, **kwargs)

    signal.signal(sig, wrapper)



class ProdThread:
    """
    provided func has to accept two arguments:
    - queue = queue.Queue()
    - running = threading.Event()
    """

    def __init__(self, func):
        self.func = func

        self.thread = None
        self.queue = Queue()
        self.running = Event()

        prepend_signal(signal.SIGINT, self.stop)


    def target(self):
        self.running.set()
        self.func(self.queue, self.running)
        self.running.clear()

    def start(self):
        if not self.thread:
            self.thread = thread = Thread(target=self.target)
            thread.start()

    def stop(self, *args): # signal() gives some extra args
        self.running.clear()
        if self.thread:
            self.thread.join()
            self.thread = None