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

from django.db import migrations, models

from openslides.utils.autoupdate import inform_changed_data_receiver


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 (except 'Default')

    But only run this migration if:
    - there are groups in the database,
    - the name of the first group is 'Guests',
    - the name of the second group is 'Registered users'.
    """
    # Disconnect autoupdate. We do not want to trigger it here.
    models.signals.post_save.disconnect(dispatch_uid='inform_changed_data_receiver')

    User = apps.get_model('users', 'User')
    Group = apps.get_model('auth', 'Group')

    try:
        group_default = Group.objects.get(pk=1)
        group_registered = Group.objects.get(pk=2)
    except Group.DoesNotExist:
        # One of the groups does not exist. Just do nothing.
        pass
    else:
        if group_default.name == 'Guests' and group_registered.name == 'Registered users':
            # Rename groups pk 1 and 2.
            group_default.name = 'Default'
            group_default.save()
            group_registered.name = 'Previous group Registered'
            group_registered.save()

            # Move users without groups to group pk 2.
            users = User.objects.all()
            for user in users:
                if not user.groups.exists():
                    user.groups.add(group_registered)

            # Copy permissions of group pk 2 to all other groups except pk 1.
            groups = Group.objects.filter(pk__gt=2)
            for group in groups:
                for permission in group_registered.permissions.all():
                    group.permissions.add(permission)

    # Reconnect autoupdate.
    models.signals.post_save.connect(
        inform_changed_data_receiver,
        dispatch_uid='inform_changed_data_receiver')


class Migration(migrations.Migration):

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

    operations = [
        migrations.RunPython(migrate_groups_and_user_permissions),
    ]