from __future__ import unicode_literals
from django.conf import settings
from django.db import models
from django.utils import timezone
from django.utils.encoding import python_2_unicode_compatible

from . import get_ghost_user, get_system_user


def get_system_user_id():
    return get_system_user().id


@python_2_unicode_compatible
class EventFlag(models.Model):
    event = models.ForeignKey('dav_events.Event', related_name='flags')
    status = models.ForeignKey('dav_events.EventStatus',
                               on_delete=models.PROTECT,
                               related_name='+')
    timestamp = models.DateTimeField(default=timezone.now)
    user = models.ForeignKey(settings.AUTH_USER_MODEL,
                             default=get_system_user_id,
                             on_delete=models.SET(get_ghost_user),
                             related_name='+')

    class Meta:
        ordering = ['event', 'timestamp', 'status']

    def __str__(self):
        s = '{status} - {timestamp}'
        if self.user:
            s += ' by user {user}'
        return s.format(status=self.status, timestamp=self.timestamp.strftime('%d.%m.%Y %H:%M:%S'),
                        user=self.user)