from unittest import mock

from django.contrib.contenttypes.checks import check_model_name_lengths
from django.contrib.contenttypes.fields import GenericForeignKey, GenericRelation
from django.contrib.contenttypes.models import ContentType
from django.core import checks
from django.db import models
from django.test import SimpleTestCase, override_settings
from django.test.utils import isolate_apps


@isolate_apps("contenttypes_tests", attr_name="apps")
class GenericForeignKeyTests(SimpleTestCase):
    def test_missing_content_type_field(self):
        class TaggedItem(models.Model):
            # no content_type field
            object_id = models.PositiveIntegerField()
            content_object = GenericForeignKey()

        expected = [
            checks.Error(
                "The GenericForeignKey content type references the nonexistent "
                "field 'TaggedItem.content_type'.",
                obj=TaggedItem.content_object,
                id="contenttypes.E002",
            )
        ]
        self.assertEqual(TaggedItem.content_object.check(), expected)

    def test_invalid_content_type_field(self):
        class Model(models.Model):
            content_type = models.IntegerField()  # should be ForeignKey
            object_id = models.PositiveIntegerField()
            content_object = GenericForeignKey("content_type", "object_id")

        self.assertEqual(
            Model.content_object.check(),
            [
                checks.Error(
                    "'Model.content_type' is not a ForeignKey.",
                    hint=(
                        "GenericForeignKeys must use a ForeignKey to "
                        "'contenttypes.ContentType' as the 'content_type' field."
                    ),
                    obj=Model.content_object,
                    id="contenttypes.E003",
                )
            ],
        )

    def test_content_type_field_pointing_to_wrong_model(self):
        class Model(models.Model):
            content_type = models.ForeignKey(
                "self", models.CASCADE
            )  # should point to ContentType
            object_id = models.PositiveIntegerField()
            content_object = GenericForeignKey("content_type", "object_id")

        self.assertEqual(
            Model.content_object.check(),
            [
                checks.Error(
                    "'Model.content_type' is not a ForeignKey to "
                    "'contenttypes.ContentType'.",
                    hint=(
                        "GenericForeignKeys must use a ForeignKey to "
                        "'contenttypes.ContentType' as the 'content_type' field."
                    ),
                    obj=Model.content_object,
                    id="contenttypes.E004",
                )
            ],
        )

    def test_missing_object_id_field(self):
        class TaggedItem(models.Model):
            content_type = models.ForeignKey(ContentType, models.CASCADE)
            # missing object_id field
            content_object = GenericForeignKey()

        self.assertEqual(
            TaggedItem.content_object.check(),
            [
                checks.Error(
                    "The GenericForeignKey object ID references the nonexistent "
                    "field 'object_id'.",
                    obj=TaggedItem.content_object,
                    id="contenttypes.E001",
                )
            ],
        )

    def test_field_name_ending_with_underscore(self):
        class Model(models.Model):
            content_type = models.ForeignKey(ContentType, models.CASCADE)
            object_id = models.PositiveIntegerField()
            content_object_ = GenericForeignKey("content_type", "object_id")

        self.assertEqual(
            Model.content_object_.check(),
            [
                checks.Error(
                    "Field names must not end with an underscore.",
                    obj=Model.content_object_,
                    id="fields.E001",
                )
            ],
        )

    @override_settings(
        INSTALLED_APPS=[
            "django.contrib.auth",
            "django.contrib.contenttypes",
            "contenttypes_tests",
        ]
    )
    def test_generic_foreign_key_checks_are_performed(self):
        class Model(models.Model):
            content_object = GenericForeignKey()

        with mock.patch.object(GenericForeignKey, "check") as check:
            checks.run_checks(app_configs=self.apps.get_app_configs())
        check.assert_called_once_with()


@isolate_apps("contenttypes_tests")
class GenericRelationTests(SimpleTestCase):
    def test_valid_generic_relationship(self):
        class TaggedItem(models.Model):
            content_type = models.ForeignKey(ContentType, models.CASCADE)
            object_id = models.PositiveIntegerField()
            content_object = GenericForeignKey()

        class Bookmark(models.Model):
            tags = GenericRelation("TaggedItem")

        self.assertEqual(Bookmark.tags.field.check(), [])

    def test_valid_generic_relationship_with_explicit_fields(self):
        class TaggedItem(models.Model):
            custom_content_type = models.ForeignKey(ContentType, models.CASCADE)
            custom_object_id = models.PositiveIntegerField()
            content_object = GenericForeignKey(
                "custom_content_type", "custom_object_id"
            )

        class Bookmark(models.Model):
            tags = GenericRelation(
                "TaggedItem",
                content_type_field="custom_content_type",
                object_id_field="custom_object_id",
            )

        self.assertEqual(Bookmark.tags.field.check(), [])

    def test_pointing_to_missing_model(self):
        class Model(models.Model):
            rel = GenericRelation("MissingModel")

        self.assertEqual(
            Model.rel.field.check(),
            [
                checks.Error(
                    "Field defines a relation with model 'MissingModel', "
                    "which is either not installed, or is abstract.",
                    obj=Model.rel.field,
                    id="fields.E300",
                )
            ],
        )

    def test_valid_self_referential_generic_relationship(self):
        class Model(models.Model):
            rel = GenericRelation("Model")
            content_type = models.ForeignKey(ContentType, models.CASCADE)
            object_id = models.PositiveIntegerField()
            content_object = GenericForeignKey("content_type", "object_id")

        self.assertEqual(Model.rel.field.check(), [])

    def test_missing_generic_foreign_key(self):
        class TaggedItem(models.Model):
            content_type = models.ForeignKey(ContentType, models.CASCADE)
            object_id = models.PositiveIntegerField()

        class Bookmark(models.Model):
            tags = GenericRelation("TaggedItem")

        self.assertEqual(
            Bookmark.tags.field.check(),
            [
                checks.Error(
                    "The GenericRelation defines a relation with the model "
                    "'contenttypes_tests.TaggedItem', but that model does not have a "
                    "GenericForeignKey.",
                    obj=Bookmark.tags.field,
                    id="contenttypes.E004",
                )
            ],
        )

    @override_settings(TEST_SWAPPED_MODEL="contenttypes_tests.Replacement")
    def test_pointing_to_swapped_model(self):
        class Replacement(models.Model):
            pass

        class SwappedModel(models.Model):
            content_type = models.ForeignKey(ContentType, models.CASCADE)
            object_id = models.PositiveIntegerField()
            content_object = GenericForeignKey()

            class Meta:
                swappable = "TEST_SWAPPED_MODEL"

        class Model(models.Model):
            rel = GenericRelation("SwappedModel")

        self.assertEqual(
            Model.rel.field.check(),
            [
                checks.Error(
                    "Field defines a relation with the model "
                    "'contenttypes_tests.SwappedModel', "
                    "which has been swapped out.",
                    hint=(
                        "Update the relation to point at 'settings.TEST_SWAPPED_MODEL'."
                    ),
                    obj=Model.rel.field,
                    id="fields.E301",
                )
            ],
        )

    def test_field_name_ending_with_underscore(self):
        class TaggedItem(models.Model):
            content_type = models.ForeignKey(ContentType, models.CASCADE)
            object_id = models.PositiveIntegerField()
            content_object = GenericForeignKey()

        class InvalidBookmark(models.Model):
            tags_ = GenericRelation("TaggedItem")

        self.assertEqual(
            InvalidBookmark.tags_.field.check(),
            [
                checks.Error(
                    "Field names must not end with an underscore.",
                    obj=InvalidBookmark.tags_.field,
                    id="fields.E001",
                )
            ],
        )


@isolate_apps("contenttypes_tests", attr_name="apps")
class ModelCheckTests(SimpleTestCase):
    def test_model_name_too_long(self):
        model = type("A" * 101, (models.Model,), {"__module__": self.__module__})
        self.assertEqual(
            check_model_name_lengths(self.apps.get_app_configs()),
            [
                checks.Error(
                    "Model names must be at most 100 characters (got 101).",
                    obj=model,
                    id="contenttypes.E005",
                )
            ],
        )

    def test_model_name_max_length(self):
        type("A" * 100, (models.Model,), {"__module__": self.__module__})
        self.assertEqual(check_model_name_lengths(self.apps.get_app_configs()), [])