from dataclasses import dataclass

from django.contrib.contenttypes.models import ContentType
from django.db import transaction
from django.db.models import Q
from django.utils import timezone

from notifications.cache import invalidate_unread_summary
from notifications.models import Notification
from notifications.realtime import send_notifications_read_all_event
from requests_app.models import Request as EmployeeRequest


@dataclass(frozen=True)
class RequestNotificationReadResult:
    notification_ids: list[int]
    count: int


class RequestNotificationReadService:
    """Отмечает прочитанными уведомления только выбранного заявления."""

    def mark_request_notifications_as_read(
        self,
        *,
        user,
        employee_request: EmployeeRequest,
    ) -> RequestNotificationReadResult:
        request_content_type = ContentType.objects.get_for_model(EmployeeRequest)
        request_id = employee_request.id
        request_id_text = str(request_id)

        queryset = (
            Notification.objects.filter(
                recipient_id=user.id,
                unread=True,
                deleted=False,
                verb__startswith="request_",
            )
            .filter(
                Q(data__request_id=request_id)
                | Q(data__request_id=request_id_text)
                | Q(
                    target_content_type=request_content_type,
                    target_object_id=request_id_text,
                )
                | Q(
                    action_object_content_type=request_content_type,
                    action_object_object_id=request_id_text,
                )
            )
            .distinct()
        )
        notification_ids = list(queryset.values_list("id", flat=True))

        if not notification_ids:
            return RequestNotificationReadResult(notification_ids=[], count=0)

        count = Notification.objects.filter(id__in=notification_ids).update(
            unread=False,
            timestamp_read=timezone.now(),
        )
        invalidate_unread_summary(user.id)

        def notify_after_commit():
            invalidate_unread_summary(user.id)
            send_notifications_read_all_event(user.id, notification_ids)

        transaction.on_commit(notify_after_commit)
        return RequestNotificationReadResult(
            notification_ids=notification_ids,
            count=count,
        )