# -*- coding: utf-8 -*-
from django.db import migrations
from django.db.models import Q


def convert_manage_perms(apps, schema_editor):
    """
    Use the permissions of `kfet.auth.models.Group` model, instead of using the
    `manage_perms` permission, which is deleted, of `kfet.models.Account`.

    `Group` which have this last permission will get the permissions:
    `kfetauth.view_group`, `kfetauth.add_group` and `kfetauth.change_group`.
    """
    Group = apps.get_model('auth', 'Group')
    Permission = apps.get_model('auth', 'Permission')
    ContentType = apps.get_model('contenttypes', 'ContentType')

    try:
        old_p = Permission.objects.get(
            content_type__app_label='kfet',
            content_type__model='account',
            codename='manage_perms',
        )
    except Permission.DoesNotExist:
        return

    groups = old_p.group_set.all()

    ct_group, _ = ContentType.objects.get_or_create(
        app_label='kfetauth',
        model='group',
    )

    view_p, _ = Permission.objects.get_or_create(
        content_type=ct_group, codename='view_group',
        defaults={'name': 'Can view Groupe'})
    add_p, _ = Permission.objects.get_or_create(
        content_type=ct_group, codename='add_group',
        defaults={'name': 'Can add Groupe'})
    change_p, _ = Permission.objects.get_or_create(
        content_type=ct_group, codename='change_group',
        defaults={'name': 'Can change Group'})

    GroupPermission = Group.permissions.through

    GroupPermission.objects.bulk_create([
        GroupPermission(permission=p, group=g)
        for g in groups
        for p in (view_p, add_p, change_p)
    ])

    old_p.delete()


def delete_unused_permissions(apps, schema_editor):
    Permission = apps.get_model('auth', 'Permission')

    to_delete_q = Q(content_type__model='genericteamtoken') | Q(
        content_type__model='group',
        codename='delete_group',
    )

    to_delete_q &= Q(content_type__app_label='kfetauth')

    Permission.objects.filter(to_delete_q).delete()


class Migration(migrations.Migration):
    """
    Data migration about permissions.
    """
    dependencies = [
        ('kfetauth', '0002_existing_groups'),
        ('auth', '0006_require_contenttypes_0002'),
        ('contenttypes', '0002_remove_content_type_name'),
    ]

    operations = [
        migrations.RunPython(convert_manage_perms),
        migrations.RunPython(delete_unused_permissions),
    ]