import shutil
import tempfile
from pathlib import Path

from django.contrib.auth import get_user_model
from django.test import TestCase, override_settings

from artifacts.models import Artifact, UserProfile
from artifacts.storage import QuotaExceeded, make_room_for

User = get_user_model()


@override_settings()
class MakeRoomForTestCase(TestCase):
    @classmethod
    def setUpClass(cls):
        super().setUpClass()
        cls.artifacts_root = Path(tempfile.mkdtemp(prefix="agentfeed-test-storage-"))
        cls.settings_override = override_settings(ARTIFACTS_ROOT=cls.artifacts_root)
        cls.settings_override.enable()

    @classmethod
    def tearDownClass(cls):
        cls.settings_override.disable()
        shutil.rmtree(cls.artifacts_root, ignore_errors=True)
        super().tearDownClass()

    def setUp(self):
        self.user = User.objects.create_user(username="quota-test", password="pw")

    def make_artifact(self, artifact_id, size_bytes, is_kept=False):
        return Artifact.objects.create(
            id=artifact_id,
            owner=self.user,
            source="test",
            title=f"Artifact {artifact_id}",
            kind=Artifact.MARKDOWN,
            day="2026-01-01",
            path=f"test/2026-01-01/{artifact_id}.html",
            original_kind=Artifact.MARKDOWN,
            size_bytes=size_bytes,
            is_kept=is_kept,
        )

    def set_quota(self, quota_bytes):
        UserProfile.objects.update_or_create(user=self.user, defaults={"quota_bytes": quota_bytes})

    def test_unwinnable_eviction_deletes_nothing(self):
        """Regression test for issue #006: a doomed post must not destroy
        unkept artifacts on its way to still failing."""
        self.set_quota(1000)
        self.make_artifact("kept0001", size_bytes=900, is_kept=True)
        self.make_artifact("unkept01", size_bytes=50)
        self.make_artifact("unkept02", size_bytes=40)

        with self.assertRaises(QuotaExceeded):
            make_room_for(self.user, incoming_bytes=200)

        self.assertTrue(Artifact.objects.filter(id="unkept01").exists())
        self.assertTrue(Artifact.objects.filter(id="unkept02").exists())
        self.assertTrue(Artifact.objects.filter(id="kept0001").exists())

    def test_successful_eviction_frees_only_what_is_needed(self):
        self.set_quota(1000)
        self.make_artifact("kept0001", size_bytes=500, is_kept=True)
        self.make_artifact("oldest01", size_bytes=200)
        self.make_artifact("newest01", size_bytes=200)
        Artifact.objects.filter(id="oldest01").update(created_at="2026-01-01T00:00:00Z")
        Artifact.objects.filter(id="newest01").update(created_at="2026-06-01T00:00:00Z")

        evicted = make_room_for(self.user, incoming_bytes=300)

        self.assertEqual(set(evicted), {"oldest01"})
        self.assertFalse(Artifact.objects.filter(id="oldest01").exists())
        self.assertTrue(Artifact.objects.filter(id="newest01").exists())
        self.assertTrue(Artifact.objects.filter(id="kept0001").exists())

    def test_incoming_larger_than_quota_deletes_nothing(self):
        self.set_quota(1000)
        self.make_artifact("unkept01", size_bytes=50)

        with self.assertRaises(QuotaExceeded):
            make_room_for(self.user, incoming_bytes=2000)

        self.assertTrue(Artifact.objects.filter(id="unkept01").exists())