import persisting_theory


class ActivityRegistry(persisting_theory.Registry):
    look_into = 'activities'

    def _register_for_model(self, model, attr, value):
        key = model._meta.label
        d = self.setdefault(key, {'consumers': []})
        d[attr] = value

    def register_serializer(self, serializer_class):
        model = serializer_class.Meta.model
        self._register_for_model(model, 'serializer', serializer_class)
        return serializer_class

    def register_consumer(self, label):
        def decorator(func):
            consumers = self[label]['consumers']
            if func not in consumers:
                consumers.append(func)
            return func
        return decorator


registry = ActivityRegistry()




def send(obj):
    conf = registry[obj.__class__._meta.label]
    consumers = conf['consumers']
    if not consumers:
        return
    serializer = conf['serializer'](obj)
    for consumer in consumers:
        consumer(data=serializer.data, obj=obj)