from django.db import migrations


def set_collection_path_collation(apps, schema_editor):
    """
    Treebeard's path comparison logic can fail on certain locales such as sk_SK, which
    sort numbers after letters. To avoid this, we explicitly set the collation for the
    'path' column to the (non-locale-specific) 'C' collation.

    See: https://groups.google.com/d/msg/wagtail/q0leyuCnYWI/I9uDvVlyBAAJ
    """
    if schema_editor.connection.vendor == "postgresql":
        schema_editor.execute(
            """
            ALTER TABLE wagtailcore_collection ALTER COLUMN path TYPE VARCHAR(255) COLLATE "C"
        """
        )


class Migration(migrations.Migration):

    dependencies = [
        ("wagtailcore", "0026_group_collection_permission"),
    ]

    operations = [
        migrations.RunPython(set_collection_path_collation, migrations.RunPython.noop),
    ]