from django.core.exceptions import ImproperlyConfigured

from django.db import models

from django.test import SimpleTestCase, override_settings

from django.test.utils import isolate_apps

class MyBigAutoField(models.BigAutoField):

    pass

@isolate_apps("model_options")

class TestDefaultPK(SimpleTestCase):

    @override_settings(DEFAULT_AUTO_FIELD="django.db.models.NonexistentAutoField")

    def test_default_auto_field_setting_nonexistent(self):

        msg = (

            "DEFAULT_AUTO_FIELD refers to the module "

            "'django.db.models.NonexistentAutoField' that could not be "

            "imported."

        )

        with self.assertRaisesMessage(ImproperlyConfigured, msg):

            class Model(models.Model):

                pass

    @isolate_apps("model_options.apps.ModelPKNonexistentConfig")

    def test_app_default_auto_field_nonexistent(self):

        msg = (

            "model_options.apps.ModelPKNonexistentConfig.default_auto_field "

            "refers to the module 'django.db.models.NonexistentAutoField' "

            "that could not be imported."

        )

        with self.assertRaisesMessage(ImproperlyConfigured, msg):

            class Model(models.Model):

                pass

    @override_settings(DEFAULT_AUTO_FIELD="django.db.models.TextField")

    def test_default_auto_field_setting_non_auto(self):

        msg = (

            "Primary key 'django.db.models.TextField' referred by "

            "DEFAULT_AUTO_FIELD must subclass AutoField."

        )

        with self.assertRaisesMessage(ValueError, msg):

            class Model(models.Model):

                pass

    @isolate_apps("model_options.apps.ModelPKNonAutoConfig")

    def test_app_default_auto_field_non_auto(self):

        msg = (

            "Primary key 'django.db.models.TextField' referred by "

            "model_options.apps.ModelPKNonAutoConfig.default_auto_field must "

            "subclass AutoField."

        )

        with self.assertRaisesMessage(ValueError, msg):

            class Model(models.Model):

                pass

    @override_settings(DEFAULT_AUTO_FIELD=None)

    def test_default_auto_field_setting_none(self):

        msg = "DEFAULT_AUTO_FIELD must not be empty."

        with self.assertRaisesMessage(ImproperlyConfigured, msg):

            class Model(models.Model):

                pass

    @isolate_apps("model_options.apps.ModelPKNoneConfig")

    def test_app_default_auto_field_none(self):

        msg = (

            "model_options.apps.ModelPKNoneConfig.default_auto_field must not "

            "be empty."

        )

        with self.assertRaisesMessage(ImproperlyConfigured, msg):

            class Model(models.Model):

                pass

    @isolate_apps("model_options.apps.ModelDefaultPKConfig")

    @override_settings(DEFAULT_AUTO_FIELD="django.db.models.SmallAutoField")

    def test_default_auto_field_setting(self):

        class Model(models.Model):

            pass

        self.assertIsInstance(Model._meta.pk, models.SmallAutoField)

    @override_settings(

        DEFAULT_AUTO_FIELD="model_options.test_default_pk.MyBigAutoField"

    )

    def test_default_auto_field_setting_bigautofield_subclass(self):

        class Model(models.Model):

            pass

        self.assertIsInstance(Model._meta.pk, MyBigAutoField)

    @isolate_apps("model_options.apps.ModelPKConfig")

    @override_settings(DEFAULT_AUTO_FIELD="django.db.models.AutoField")

    def test_app_default_auto_field(self):

        class Model(models.Model):

            pass

        self.assertIsInstance(Model._meta.pk, models.SmallAutoField)

    @isolate_apps("model_options.apps.ModelDefaultPKConfig")

    @override_settings(DEFAULT_AUTO_FIELD="django.db.models.SmallAutoField")

    def test_m2m_default_auto_field_setting(self):

        class M2MModel(models.Model):

            m2m = models.ManyToManyField("self")

        m2m_pk = M2MModel._meta.get_field("m2m").remote_field.through._meta.pk

        self.assertIsInstance(m2m_pk, models.SmallAutoField)

    @isolate_apps("model_options.apps.ModelPKConfig")

    @override_settings(DEFAULT_AUTO_FIELD="django.db.models.AutoField")

    def test_m2m_app_default_auto_field(self):

        class M2MModel(models.Model):

            m2m = models.ManyToManyField("self")

        m2m_pk = M2MModel._meta.get_field("m2m").remote_field.through._meta.pk

        self.assertIsInstance(m2m_pk, models.SmallAutoField)