# -*- coding: utf-8 -*-
# Generated by Django 1.9.7 on 2016-08-01 14:54
from __future__ import unicode_literals

from django.core.exceptions import ObjectDoesNotExist
from django.db import migrations


def migrate_groups_and_user_permissions(apps, schema_editor):
    """
    This function migrates the database to the new groups logic:
    - Rename Group 'Anonymous' (pk=1) to 'Default'
    - Rename Group 'Registered users' (pk=2) to 'Previous group Registered'
    - Add all users who are not in any group to this group (pk=2)
    - Add all permissions of 'Previous group Registered' to all other groups (exclude 'Default')

    But only do this migration if:
    - there are groups in the database
    - the name of the first group is 'Guests'.
    """
    User = apps.get_model('users', 'User')
    Group = apps.get_model('auth', 'Group')

    if Group.objects.exists():
        try:
            group_default = Group.objects.filter(pk=1)
            if group_default.get().name == 'Guests':
                group_default.update(name='Default')

                group_old_registered = Group.objects.filter(pk=2)
                group_old_registered.update(name='Previous group Registered')
                group_old_registered = group_old_registered.get()

                users = User.objects.all()
                for user in users:
                    if not user.groups.exists():
                        user.groups.add(group_old_registered.pk)

                groups = Group.objects.filter(pk__gt=2)
                for group in groups:
                    for permission in group_old_registered.permissions.all():
                        group.permissions.add(permission)
        except ObjectDoesNotExist:
            # If the first or second group doesn't exists, just pass this migraition
            pass


class Migration(migrations.Migration):

    dependencies = [
        ('users', '0003_user_number'),
    ]

    operations = [
        migrations.RunPython(migrate_groups_and_user_permissions),
    ]