#!/usr/bin/python2 -O

import inspect

import qubes.events
import qubes.plugins

class ExtensionPlugin(qubes.plugins.Plugin):
    def __init__(cls, name, bases, dict_):
        super(ExtensionPlugin, cls).__init__(name, bases, dict_)
        cls._instance = None

    def __call__(cls, *args, **kwargs):
        if cls._instance is None:
            cls._instance = super(ExtensionPlugin, cls).__call__(*args, **kwargs)
        return cls._instance

class Extension(object):
    __metaclass__ = ExtensionPlugin
    def __init__(self):
        for name in dir(self):
            attr = getattr(self, name)
            if not ishook(attr):
                continue

            if attr.ho_vm is not None:
                attr.ho_vm.add_hook(event, attr)
            else:
                # global hook
                qubes.events.add_system_hook(event, attr)

def init():
    for ext in Extension.register.values():
        instance = ext()

__all__ = qubes.plugins.load(__file__)