from __future__ import annotations

from datetime import datetime, timezone

from django.test import SimpleTestCase

from pobsync.retention import Snapshot, build_retention_plan


class RetentionTests(SimpleTestCase):
    def test_always_keeps_newest_snapshot(self) -> None:
        snapshots = [
            Snapshot("scheduled", "old", "/x/old", datetime(2026, 5, 18, tzinfo=timezone.utc), "success", None),
            Snapshot("scheduled", "new", "/x/new", datetime(2026, 5, 19, tzinfo=timezone.utc), "failed", None),
        ]

        plan = build_retention_plan(
            snapshots,
            retention={"daily": 0, "weekly": 0, "monthly": 0, "yearly": 0},
            now=datetime(2026, 5, 19, tzinfo=timezone.utc),
        )

        self.assertEqual(plan.keep, {"new"})
        self.assertEqual(plan.reasons["new"], ["newest"])