from celery.task import task
from celery.task.base import PeriodicTask
from celery.task.schedules import schedule
from celery.execute import send_task

from oyster.client import Client

client = Client()
client.db.status.drop()
client.db.status.insert({'update_queue': 0})


@task(ignore_result=True)
def update_task(doc_id):
    # maybe fetch doc instead?
    doc = client.db.tracked.find_one({'_id': doc_id})
    client.update(doc)
    for hook in doc.get('post_update_hooks', []):
        send_task(hook, (doc_id,))
    client.db.status.update({}, {'$inc': {'update_queue': -1}})


class UpdateTaskScheduler(PeriodicTask):

    # 60s tick
    run_every = 60

    def run(self):

        # if the update queue isn't empty, wait to add more
        # (currently the only way we avoid duplicates)
        # alternate option would be to set a _queued flag on documents
        if client.db.status.find_one()['update_queue']:
            pass

        next_set = client.get_update_queue()
        for doc in next_set:
            update_task.delay(doc['_id'])
            client.db.status.update({}, {'$inc': {'update_queue': 1}})