from .singleton import Singleton


class SceneManager(metaclass=Singleton):
    def __init__(self, scene):
        super().__init__()
        self._scene = scene
        self._scene.load()

    def change_scene(self, new_scene):
        self._scene.unload()
        self._scene = new_scene
        self._scene.load()

    def step(self):
        for entity in self._scene.entities:
            if entity.script is not None:
                entity.script(entity)