from unittest import mock

from django.core.exceptions import ValidationError
from django.db import IntegrityError, connection, models
from django.db.models.constraints import BaseConstraint
from django.test import SimpleTestCase, TestCase, skipUnlessDBFeature

from .models import ChildModel, Product, UniqueConstraintProduct


def get_constraints(table):
    with connection.cursor() as cursor:
        return connection.introspection.get_constraints(cursor, table)


class BaseConstraintTests(SimpleTestCase):
    def test_constraint_sql(self):
        c = BaseConstraint('name')
        msg = 'This method must be implemented by a subclass.'
        with self.assertRaisesMessage(NotImplementedError, msg):
            c.constraint_sql(None, None)

    def test_create_sql(self):
        c = BaseConstraint('name')
        msg = 'This method must be implemented by a subclass.'
        with self.assertRaisesMessage(NotImplementedError, msg):
            c.create_sql(None, None)

    def test_remove_sql(self):
        c = BaseConstraint('name')
        msg = 'This method must be implemented by a subclass.'
        with self.assertRaisesMessage(NotImplementedError, msg):
            c.remove_sql(None, None)


class CheckConstraintTests(TestCase):
    def test_eq(self):
        check1 = models.Q(price__gt=models.F('discounted_price'))
        check2 = models.Q(price__lt=models.F('discounted_price'))
        self.assertEqual(
            models.CheckConstraint(check=check1, name='price'),
            models.CheckConstraint(check=check1, name='price'),
        )
        self.assertEqual(models.CheckConstraint(check=check1, name='price'), mock.ANY)
        self.assertNotEqual(
            models.CheckConstraint(check=check1, name='price'),
            models.CheckConstraint(check=check1, name='price2'),
        )
        self.assertNotEqual(
            models.CheckConstraint(check=check1, name='price'),
            models.CheckConstraint(check=check2, name='price'),
        )
        self.assertNotEqual(models.CheckConstraint(check=check1, name='price'), 1)

    def test_repr(self):
        check = models.Q(price__gt=models.F('discounted_price'))
        name = 'price_gt_discounted_price'
        constraint = models.CheckConstraint(check=check, name=name)
        self.assertEqual(
            repr(constraint),
            "<CheckConstraint: check='{}' name='{}'>".format(check, name),
        )

    def test_deconstruction(self):
        check = models.Q(price__gt=models.F('discounted_price'))
        name = 'price_gt_discounted_price'
        constraint = models.CheckConstraint(check=check, name=name)
        path, args, kwargs = constraint.deconstruct()
        self.assertEqual(path, 'django.db.models.CheckConstraint')
        self.assertEqual(args, ())
        self.assertEqual(kwargs, {'check': check, 'name': name})

    @skipUnlessDBFeature('supports_table_check_constraints')
    def test_database_constraint(self):
        Product.objects.create(price=10, discounted_price=5)
        with self.assertRaises(IntegrityError):
            Product.objects.create(price=10, discounted_price=20)

    @skipUnlessDBFeature('supports_table_check_constraints', 'can_introspect_check_constraints')
    def test_name(self):
        constraints = get_constraints(Product._meta.db_table)
        for expected_name in (
            'price_gt_discounted_price',
            'constraints_product_price_gt_0',
        ):
            with self.subTest(expected_name):
                self.assertIn(expected_name, constraints)

    @skipUnlessDBFeature('supports_table_check_constraints', 'can_introspect_check_constraints')
    def test_abstract_name(self):
        constraints = get_constraints(ChildModel._meta.db_table)
        self.assertIn('constraints_childmodel_adult', constraints)


class UniqueConstraintTests(TestCase):
    @classmethod
    def setUpTestData(cls):
        cls.p1, cls.p2 = UniqueConstraintProduct.objects.bulk_create([
            UniqueConstraintProduct(name='p1', color='red'),
            UniqueConstraintProduct(name='p2'),
        ])

    def test_eq(self):
        self.assertEqual(
            models.UniqueConstraint(fields=['foo', 'bar'], name='unique'),
            models.UniqueConstraint(fields=['foo', 'bar'], name='unique'),
        )
        self.assertEqual(
            models.UniqueConstraint(fields=['foo', 'bar'], name='unique'),
            mock.ANY,
        )
        self.assertNotEqual(
            models.UniqueConstraint(fields=['foo', 'bar'], name='unique'),
            models.UniqueConstraint(fields=['foo', 'bar'], name='unique2'),
        )
        self.assertNotEqual(
            models.UniqueConstraint(fields=['foo', 'bar'], name='unique'),
            models.UniqueConstraint(fields=['foo', 'baz'], name='unique'),
        )
        self.assertNotEqual(models.UniqueConstraint(fields=['foo', 'bar'], name='unique'), 1)

    def test_eq_with_condition(self):
        self.assertEqual(
            models.UniqueConstraint(
                fields=['foo', 'bar'], name='unique',
                condition=models.Q(foo=models.F('bar'))
            ),
            models.UniqueConstraint(
                fields=['foo', 'bar'], name='unique',
                condition=models.Q(foo=models.F('bar'))),
        )
        self.assertNotEqual(
            models.UniqueConstraint(
                fields=['foo', 'bar'],
                name='unique',
                condition=models.Q(foo=models.F('bar'))
            ),
            models.UniqueConstraint(
                fields=['foo', 'bar'],
                name='unique',
                condition=models.Q(foo=models.F('baz'))
            ),
        )

    def test_repr(self):
        fields = ['foo', 'bar']
        name = 'unique_fields'
        constraint = models.UniqueConstraint(fields=fields, name=name)
        self.assertEqual(
            repr(constraint),
            "<UniqueConstraint: fields=('foo', 'bar') name='unique_fields'>",
        )

    def test_repr_with_condition(self):
        constraint = models.UniqueConstraint(
            fields=['foo', 'bar'],
            name='unique_fields',
            condition=models.Q(foo=models.F('bar')),
        )
        self.assertEqual(
            repr(constraint),
            "<UniqueConstraint: fields=('foo', 'bar') name='unique_fields' "
            "condition=(AND: ('foo', F(bar)))>",
        )

    def test_deconstruction(self):
        fields = ['foo', 'bar']
        name = 'unique_fields'
        constraint = models.UniqueConstraint(fields=fields, name=name)
        path, args, kwargs = constraint.deconstruct()
        self.assertEqual(path, 'django.db.models.UniqueConstraint')
        self.assertEqual(args, ())
        self.assertEqual(kwargs, {'fields': tuple(fields), 'name': name})

    def test_deconstruction_with_condition(self):
        fields = ['foo', 'bar']
        name = 'unique_fields'
        condition = models.Q(foo=models.F('bar'))
        constraint = models.UniqueConstraint(fields=fields, name=name, condition=condition)
        path, args, kwargs = constraint.deconstruct()
        self.assertEqual(path, 'django.db.models.UniqueConstraint')
        self.assertEqual(args, ())
        self.assertEqual(kwargs, {'fields': tuple(fields), 'name': name, 'condition': condition})

    def test_database_constraint(self):
        with self.assertRaises(IntegrityError):
            UniqueConstraintProduct.objects.create(name=self.p1.name, color=self.p1.color)

    def test_model_validation(self):
        msg = 'Unique constraint product with this Name and Color already exists.'
        with self.assertRaisesMessage(ValidationError, msg):
            UniqueConstraintProduct(name=self.p1.name, color=self.p1.color).validate_unique()

    def test_model_validation_with_condition(self):
        """Partial unique constraints are ignored by Model.validate_unique()."""
        UniqueConstraintProduct(name=self.p1.name, color='blue').validate_unique()
        UniqueConstraintProduct(name=self.p2.name).validate_unique()

    def test_name(self):
        constraints = get_constraints(UniqueConstraintProduct._meta.db_table)
        expected_name = 'name_color_uniq'
        self.assertIn(expected_name, constraints)

    def test_condition_must_be_q(self):
        with self.assertRaisesMessage(ValueError, 'UniqueConstraint.condition must be a Q instance.'):
            models.UniqueConstraint(name='uniq', fields=['name'], condition='invalid')
