import functools
import logging
from dataclasses import dataclass, field

from django.db import transaction
from django.db.models import Q

logger = logging.getLogger(__name__)


@dataclass
class EventDefinition:
    name: str
    description: str = ""
    example_payload: dict = field(default_factory=dict)
    schema: dict = field(default_factory=dict)


class EventRegistry:
    _events: dict[str, EventDefinition] = {}

    @classmethod
    def register(cls, event_name, *, description="", example_payload=None, schema=None):
        cls._events[event_name] = EventDefinition(
            name=event_name,
            description=description,
            example_payload=example_payload or {},
            schema=schema or {},
        )
        logger.debug(f"Event registered: {event_name}")

    @classmethod
    def emit(cls, event_name, payload: dict):
        from infrasynth.shared.settings_utils import get_setting
        from infrasynth.tenancy.context import get_current_tenant

        from . import dispatch as dispatch_module
        from .models import OutboundSubscription

        active_subs = OutboundSubscription.objects.filter(
            Q(event_name=event_name) | Q(event_name="*"),
            is_active=True,
            endpoint__is_active=True,
        ).select_related("endpoint")

        tenant = get_current_tenant()
        tenant_id = str(tenant.pk) if tenant is not None else None
        backend = get_setting("INFRASYNTH_WEBHOOKS", "DELIVERY_BACKEND", "celery")

        def _deliver(subscription):
            if backend == "sync":
                dispatch_module.deliver_webhook.apply(
                    args=(subscription.id, event_name, payload, subscription.payload_template, tenant_id)
                )
            else:
                dispatch_module.deliver_webhook.delay(
                    subscription.id, event_name, payload, subscription.payload_template, tenant_id
                )

        with transaction.atomic():
            for sub in active_subs:
                transaction.on_commit(functools.partial(_deliver, sub))

    @classmethod
    def get_registered_events(cls) -> dict[str, EventDefinition]:
        return dict(cls._events)