import logging
import signal
import threading


class State(object):
    """
    Do not create an instance of this class directly: use the instance `state` below. This state must be initiated once,
    probably when your program starts.

    This class is used to share state between threads. For example, when the program is quit, that all threads can
    detect this via the `exit_event` property being set.
    """
    def __init__(self):
        self.is_initialized = False
        self.exit_event = None

    def initialize(self):
        if self.is_initialized:
            logging.warn("Already initialized")
            return

        self.exit_event = threading.Event()
        def handle_exit(_, __):
            logging.info("Exiting.")
            self.exit_event.set()
        signal.signal(signal.SIGINT, handle_exit)
        signal.signal(signal.SIGTERM, handle_exit)

        self.is_initialized = True

    def deinitialize(self):
        if not self.is_initialized: return
        self.is_initialized = False

    def __getattribute__(self, name):
        # Enforce that the state is initialized before accessing any property (aside from the basic ones)
        if name in ("initialize", "deinitialize", "is_initialized", "__dict__", "__class__", "id", "name", "ip", "port"):
            return object.__getattribute__(self, name)

        if not object.__getattribute__(self, "is_initialized"):
            # Special case for the exit_event: if the event is set, return it without an error
            if name == "exit_event":
                exit_event = object.__getattribute__(self, "exit_event")
                if exit_event and exit_event.is_set(): return exit_event

            raise RuntimeError("State must be initialized before accessing '%s'" % name)

        return object.__getattribute__(self, name)


# Must call `.initialize` before use
state = State()