from django.core.management.base import BaseCommand
from django.utils import timezone

from podcasts.models import PodcastFeed
from podcasts.views import _in_backoff_q, _refresh_feeds


class Command(BaseCommand):
    help = 'Refresh podcast feeds (fetch new episodes from RSS)'

    def add_arguments(self, parser):
        parser.add_argument('--feed-id', type=int, help='Refresh only this feed ID (even when backing off)')
        parser.add_argument('--limit', type=int, default=0, help='Max number of feeds to refresh')

    def handle(self, *args, **options):
        qs = PodcastFeed.objects.all().order_by('last_refreshed_at')

        if options['feed_id']:
            qs = qs.filter(pk=options['feed_id'])
        else:
            # A feed failing 3+ times in a row is tried every 2, 4, 8, 16,
            # at most 24 hours instead of every hour.
            qs = qs.exclude(_in_backoff_q(timezone.now()))

        if options['limit']:
            qs = qs[: options['limit']]

        if not qs.exists():
            self.stdout.write('No feeds to refresh.')
            return

        # Parallel downloads, one per distinct feed URL (see _refresh_feeds).
        refreshed, failed, new = _refresh_feeds(qs)
        self.stdout.write(f'{refreshed} feeds refreshed, {failed} failed, +{new} episodes')