from django.test import TransactionTestCase

from polymorphic.models import PolymorphicModel, PolymorphicTypeUndefined
from polymorphic.tests.models import (
    Enhance_Base,
    Enhance_Inherit,
    Model2A,
    Model2B,
    Model2C,
    Model2D,
)
from polymorphic.utils import (
    get_base_polymorphic_model,
    reset_polymorphic_ctype,
    sort_by_subclass,
)


class UtilsTests(TransactionTestCase):
    def test_sort_by_subclass(self):
        self.assertEqual(
            sort_by_subclass(Model2D, Model2B, Model2D, Model2A, Model2C),
            [Model2A, Model2B, Model2C, Model2D, Model2D],
        )

    def test_reset_polymorphic_ctype(self):
        """
        Test the the polymorphic_ctype_id can be restored.
        """
        Model2A.objects.create(field1="A1")
        Model2D.objects.create(field1="A1", field2="B2", field3="C3", field4="D4")
        Model2B.objects.create(field1="A1", field2="B2")
        Model2B.objects.create(field1="A1", field2="B2")
        Model2A.objects.all().update(polymorphic_ctype_id=None)

        with self.assertRaises(PolymorphicTypeUndefined):
            list(Model2A.objects.all())

        reset_polymorphic_ctype(Model2D, Model2B, Model2D, Model2A, Model2C)

        self.assertQuerysetEqual(
            Model2A.objects.order_by("pk"),
            [Model2A, Model2D, Model2B, Model2B],
            transform=lambda o: o.__class__,
        )

    def test_get_base_polymorphic_model(self):
        """
        Test that finding the base polymorphic model works.
        """
        # Finds the base from every level (including lowest)
        self.assertIs(get_base_polymorphic_model(Model2D), Model2A)
        self.assertIs(get_base_polymorphic_model(Model2C), Model2A)
        self.assertIs(get_base_polymorphic_model(Model2B), Model2A)
        self.assertIs(get_base_polymorphic_model(Model2A), Model2A)

        # Properly handles multiple inheritance
        self.assertIs(get_base_polymorphic_model(Enhance_Inherit), Enhance_Base)

        # Ignores PolymorphicModel itself.
        self.assertIs(get_base_polymorphic_model(PolymorphicModel), None)

    def test_get_base_polymorphic_model_skip_abstract(self):
        """
        Skipping abstract models that can't be used for querying.
        """

        class A(PolymorphicModel):
            class Meta:
                abstract = True

        class B(A):
            pass

        class C(B):
            pass

        self.assertIs(get_base_polymorphic_model(A), None)
        self.assertIs(get_base_polymorphic_model(B), B)
        self.assertIs(get_base_polymorphic_model(C), B)

        self.assertIs(get_base_polymorphic_model(C, allow_abstract=True), A)