import threading

import contexts

class TkContext(contexts.CallableContext):
    def __init__(self, app):
        self.app = app
        self._post_signal = threading.Condition()

    @staticmethod
    def invoke(callable, args, kwargs):
        callable(*args, **kwargs)

    @staticmethod
    def invoke_and_notify(signal, callable, args, kwargs):
        with signal:
            callable(*args, **kwargs)
            signal.notify_all()

    def post(self, callable, *args, **kwargs):
        '''Adds a callable to invoke within this context.'''
        self.app.after(0, TkContext.invoke, callable, args, kwargs)

    def submit(self, callable, *args, **kwargs):
        '''Adds a callable to invoke within this context and returns when it
        has been completed.
        '''
        with self._post_signal:
            self.app.after(0, TkContext.invoke_and_notify, self._post_signal, callable, args, kwargs)
            self._post_signal.wait()