import datetime
from game_object import GameObject


class GameManager:

    _game_objects = list()
    def __init__(self, screen):

        self._last_update = None
        self._screen = screen
        self._pause = False

    @property
    def pause(self):
        return self._pause

    @pause.setter
    def pause(self, pause: bool):
        self._pause = pause

    def update(self):
        if not self._pause:
            now = datetime.datetime.now()
            self.__call_update(now - self._last_update)
            self.__call_draw()
        self._last_update = now

    def __call_update(self, deltatime):
        for go in GameManager._game_objects:
            go.update(deltatime)

    def __call_draw(self):
        for go in GameManager._game_objects:
            go.draw()

    @classmethod
    def register_game_object(cls, go: GameObject) -> bool:
        if go not in cls._game_objects:
            cls._game_objects.append(go)
            return True
        return False

    @classmethod
    def unregister_game_object(cls, go: GameObject) -> bool:
        if go in cls._game_objects:
            cls._game_objects.remove(go)
            return True
        return False