# -*- coding: utf-8 -*-
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 EventChange(models.Model):
    UPDATE = 'update'
    RAISE_FLAG = 'set_flag'
    LOWER_FLAG = 'unset_flag'
    OPERATION_CHOICES = (
        (UPDATE, 'Update'),
        (RAISE_FLAG, 'Raise Flag'),
        (LOWER_FLAG, 'Lower Flag'),
    )

    event = models.ForeignKey('dav_events.Event', related_name='changes')
    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='+')

    operation = models.CharField(max_length=20, choices=OPERATION_CHOICES)
    content = models.TextField()

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

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