import django.dispatch
from django.apps import apps
from django.dispatch.dispatcher import NO_RECEIVERS
from typing import Any, Callable, List, Tuple

from .models import Event


class EventPluginSignal(django.dispatch.Signal):
    """
    This is an extension to Django's built-in signals which differs in a way that it sends
    out it's events only to receivers which belong to plugins that are enabled for the given
    Event.
    """

    def send(self, sender: Event, **named) -> List[Tuple[Callable, Any]]:
        """
        Send signal from sender to all connected receivers that belong to
        plugins enabled for the given Event.

        sender is required to be an instance of ``pretix.base.models.Event``.
        """
        assert isinstance(sender, Event)

        responses = []
        if not self.receivers or self.sender_receivers_cache.get(sender) is NO_RECEIVERS:
            return responses

        for receiver in self._live_receivers(sender):
            # Find the Django application this belongs to
            searchpath = receiver.__module__
            app = None
            mod = None
            while "." in searchpath:
                try:
                    if apps.is_installed(searchpath):
                        app = apps.get_app_config(searchpath.split(".")[-1])
                except LookupError:
                    pass
                searchpath, mod = searchpath.rsplit(".", 1)

            # Only fire receivers from active plugins and core modules
            if (searchpath, mod) == ("pretix", "base") or (app and app.name in sender.get_plugins()):
                if not hasattr(app, 'compatibility_errors') or not app.compatibility_errors:
                    response = receiver(signal=self, sender=sender, **named)
                    responses.append((receiver, response))
        return responses

"""
This signal is sent out to get all known payment providers. Receivers should return a
subclass of pretix.base.payment.BasePaymentProvider
"""
register_payment_providers = EventPluginSignal(
    providing_args=[]
)

"""
This signal is sent out to get all known ticket outputs. Receivers should return a
subclass of pretix.base.ticketoutput.BaseTicketOutput
"""
register_ticket_outputs = EventPluginSignal(
    providing_args=[]
)

"""
This signal is sent out to get all known data exporters. Receivers should return a
subclass of pretix.base.exporter.BaseExporter
"""
register_data_exporters = EventPluginSignal(
    providing_args=[]
)

"""
This signal is sent out every time an order is placed. The order object is given
as the first argument.
"""
order_placed = EventPluginSignal(
    providing_args=["order"]
)

"""
This signal is sent out every time an order is paid. The order object is given
as the first argument.
"""
order_paid = EventPluginSignal(
    providing_args=["order"]
)