from .models import Track, Vote
from random import choice, seed

def from_json(cls, json):
    try:
        return cls.objects.get(pk=json["id"])
    except cls.DoesNotExist:
        keys = [f.name for f in cls._meta.get_fields()]
        subset = {key:json[key] for key in set(keys) & set(json.keys())}
        return cls.objects.create(**subset)

def get_unvoted(user):
    votes = set(Vote.objects.filter(user=user).values_list('track_id', flat=True))
    tracks = set(Track.objects.filter(banter_done=True).values_list('pk', flat=True))
    seed(user.username)
    try:
        random_track = choice(list(tracks - votes))
        return Track.objects.get(pk=random_track)
    except IndexError:
        return None