import requests

from django.conf import settings

from requests.exceptions import RequestException

from celery import shared_task
from celery.exceptions import SoftTimeLimitExceeded


class PendingTaskException(Exception):
    """ There are pending tasks """
    pass


@shared_task(
    bind = True,
    autoretry_for = (
        RequestException,
        SoftTimeLimitExceeded,
        PendingTaskException
    ),
    soft_time_limit = 60,
    retry_backoff = 3,
    max_retries = 1000
)
def notify(self, action, payload):
    from .models import Task, Delivery
    hook_backend = getattr(settings,'HOOK_BACKEND', None)

    if hook_backend:

        task, created = Task.objects.get_or_create(
            task_id = self.request.id,
            action = action,
            defaults={
                'payload': payload
            }
        )

        # check for pending tasks
        pending = Task.objects.filter(created__lt=task.created, success=False).exclude(pk=task.pk).count()
        if pending:
            raise PendingTaskException('Wait for pending taks')

        data = {
            'action': action,
            'payload': payload
        }

        # start delivery
        delivery = Delivery.objects.create(task = task)


        r = requests.post(hook_backend, json=data)
        delivery.response_status = r.status_code
        delivery.response_message = r.content
        delivery.save()

        if r.status_code == 200:
            task.success = True
            task.save()
        else:
            raise RequestException()

        return data
    return None