import logging

from celery import Celery, task
from datetime import timedelta
from os import environ

# Fetch the Redis connection string from the env, or use localhost by default
REDIS_URL = environ.get('REDISTOGO_URL', 'redis://localhost')

# Setup the celery instance under the 'tasks' namespace
app = Celery('tasks')

# Use Redis as our broker and define json as the default serializer
app.conf.update(
    BROKER_URL=REDIS_URL,
    CELERY_TASK_SERIALIZER='json',
    CELERY_ACCEPT_CONTENT=['json'],
    CELERYBEAT_SCHEDULE = {
        'print-fibonacci': {
            'task': 'tasks.print_fib',
            'schedule': timedelta(seconds=10)
        },
    }
)

# Define the fibonacci function for use in our task
def fib(n):
    if n > 1:
        return fib(n - 1) + fib(n - 2)
    else:
        return 1

# The periodic task itself, defined by the following decorator
@task
def print_fib():
    # Just log fibonacci(30), no more
    logging.info(fib(30))