import uuid

import django.db.models.deletion
from django.db import migrations, models


def delete_existing_submissions(apps, schema_editor):
    """Submissions predate Scope and can't be backfilled with one; wipe them."""
    Submission = apps.get_model("submissions", "Submission")
    Submission.objects.all().delete()


class Migration(migrations.Migration):
    # Deleting existing submissions (which cascades to their files/crops) fires
    # deferred FK triggers on postgres; altering the same table right after in
    # the same transaction hits "pending trigger events", so run non-atomically.
    atomic = False

    dependencies = [
        ("submissions", "0006_scope"),
    ]

    operations = [
        migrations.RunPython(delete_existing_submissions, migrations.RunPython.noop),
        migrations.AddField(
            model_name="submission",
            name="scope",
            field=models.ForeignKey(
                default=uuid.uuid4,
                help_text="The match this submission's score is for.",
                on_delete=django.db.models.deletion.CASCADE,
                related_name="submissions",
                to="submissions.scope",
            ),
            preserve_default=False,
        ),
    ]