from werkzeug.local import LocalProxy, LocalStack

_business_event_stack = LocalStack()


def _get_current_event():
    top = _business_event_stack.top
    if top is None:
        raise RuntimeError("No business event context found. Are you sure you're in a business event?")
    return top


current_event = LocalProxy(_get_current_event)


class BusinessEventContext:
    def __init__(self, event):
        self.event = event

    def __enter__(self):
        _business_event_stack.push(self.event)
        return self.event

    def __exit__(self, exc_type, exc_val, exc_tb):
        _business_event_stack.pop()