# Adapted from djpubsubhubbub. See License: http://git.participatoryculture.org/djpubsubhubbub/tree/LICENSE

from datetime import datetime, timedelta
import feedparser
import requests

from django.conf import settings
from django.contrib.sites.models import Site
from django.core.urlresolvers import reverse, Resolver404
from django.db import models
from django.utils.hashcompat import sha_constructor

from apps.push import signals
from apps.rss_feeds.models import Feed
from utils import log as logging

DEFAULT_LEASE_SECONDS = 2592000 # 30 days in seconds

class PushSubscriptionManager(models.Manager):

    def subscribe(self, topic, feed, hub=None, callback=None,
                  lease_seconds=None):
        if hub is None:
            hub = self._get_hub(topic)

        if hub is None:
            raise TypeError('hub cannot be None if the feed does not provide it')

        if lease_seconds is None:
            lease_seconds = getattr(settings, 'PUBSUBHUBBUB_LEASE_SECONDS',
                                   DEFAULT_LEASE_SECONDS)

        subscription, created = self.get_or_create(
            hub=hub, topic=topic, feed=feed)
        signals.pre_subscribe.send(sender=subscription, created=created)
        subscription.set_expiration(lease_seconds)

        if callback is None:
            # try:
            #     callback_path = reverse('push-callback', args=(subscription.pk,))
            # except Resolver404:
            #     raise TypeError('callback cannot be None if there is not a reverable URL')
            # else:
            #     # callback = 'http://' + Site.objects.get_current() + callback_path
            callback = "http://push.newsblur.com/push/%s" % subscription.pk # + callback_path

        response = self._send_request(hub, {
            'hub.mode': 'subscribe',
            'hub.callback': callback,
            'hub.topic': topic,
            'hub.verify': ['async', 'sync'],
            'hub.verify_token': subscription.generate_token('subscribe'),
            'hub.lease_seconds': lease_seconds,
        })

        if response.status_code == 204:
            subscription.verified = True
        elif response.status_code == 202: # async verification
            subscription.verified = False
        else:
            error = response.content
            logging.debug(u'   ---> [%-30s] ~FR~BKFeed failed to subscribe to push: %s' % (
                          unicode(subscription.feed)[:30], error))

        subscription.save()
        feed.setup_push()
        if subscription.verified:
            signals.verified.send(sender=subscription)
        return subscription


    def _get_hub(self, topic):
        parsed = feedparser.parse(topic)
        for link in parsed.feed.links:
            if link['rel'] == 'hub':
                return link['href']

    def _send_request(self, url, data):
        return requests.post(url, data=data)

class PushSubscription(models.Model):
    feed = models.OneToOneField(Feed, db_index=True, related_name='push')
    hub = models.URLField(db_index=True)
    topic = models.URLField(db_index=True)
    verified = models.BooleanField(default=False)
    verify_token = models.CharField(max_length=60)
    lease_expires = models.DateTimeField(default=datetime.now)

    objects = PushSubscriptionManager()

    # class Meta:
    #     unique_together = [
    #         ('hub', 'topic')
    #         ]
    
    def unsubscribe(self):
        feed = self.feed
        self.delete()
        feed.setup_push()
        
    def set_expiration(self, lease_seconds):
        self.lease_expires = datetime.now() + timedelta(
            seconds=lease_seconds)
        self.save()

    def generate_token(self, mode):
        assert self.pk is not None, \
            'Subscription must be saved before generating token'
        token = mode[:20] + sha_constructor('%s%i%s' % (
                settings.SECRET_KEY, self.pk, mode)).hexdigest()
        self.verify_token = token
        self.save()
        return token

    def __unicode__(self):
        if self.verified:
            verified = u'verified'
        else:
            verified = u'unverified'
        return u'to %s on %s: %s' % (
            self.topic, self.hub, verified)

    def __str__(self):
        return str(unicode(self))