import datetime
from unittest import mock

from django.contrib.postgres.indexes import OpClass
from django.db import (
    IntegrityError, NotSupportedError, connection, transaction,
)
from django.db.models import (
    CheckConstraint, Deferrable, F, Func, IntegerField, Q, UniqueConstraint,
)
from django.db.models.fields.json import KeyTextTransform
from django.db.models.functions import Cast, Left, Lower
from django.test import modify_settings, skipUnlessDBFeature
from django.utils import timezone

from . import PostgreSQLTestCase
from .models import (
    HotelReservation, IntegerArrayModel, RangesModel, Room, Scene,
)

try:
    from psycopg2.extras import DateRange, NumericRange

    from django.contrib.postgres.constraints import ExclusionConstraint
    from django.contrib.postgres.fields import (
        DateTimeRangeField, RangeBoundary, RangeOperators,
    )
except ImportError:
    pass


@modify_settings(INSTALLED_APPS={'append': 'django.contrib.postgres'})
class SchemaTests(PostgreSQLTestCase):
    get_opclass_query = '''
        SELECT opcname, c.relname FROM pg_opclass AS oc
        JOIN pg_index as i on oc.oid = ANY(i.indclass)
        JOIN pg_class as c on c.oid = i.indexrelid
        WHERE c.relname = %s
    '''

    def get_constraints(self, table):
        """Get the constraints on the table using a new cursor."""
        with connection.cursor() as cursor:
            return connection.introspection.get_constraints(cursor, table)

    def test_check_constraint_range_value(self):
        constraint_name = 'ints_between'
        self.assertNotIn(constraint_name, self.get_constraints(RangesModel._meta.db_table))
        constraint = CheckConstraint(
            check=Q(ints__contained_by=NumericRange(10, 30)),
            name=constraint_name,
        )
        with connection.schema_editor() as editor:
            editor.add_constraint(RangesModel, constraint)
        self.assertIn(constraint_name, self.get_constraints(RangesModel._meta.db_table))
        with self.assertRaises(IntegrityError), transaction.atomic():
            RangesModel.objects.create(ints=(20, 50))
        RangesModel.objects.create(ints=(10, 30))

    def test_check_constraint_daterange_contains(self):
        constraint_name = 'dates_contains'
        self.assertNotIn(constraint_name, self.get_constraints(RangesModel._meta.db_table))
        constraint = CheckConstraint(
            check=Q(dates__contains=F('dates_inner')),
            name=constraint_name,
        )
        with connection.schema_editor() as editor:
            editor.add_constraint(RangesModel, constraint)
        self.assertIn(constraint_name, self.get_constraints(RangesModel._meta.db_table))
        date_1 = datetime.date(2016, 1, 1)
        date_2 = datetime.date(2016, 1, 4)
        with self.assertRaises(IntegrityError), transaction.atomic():
            RangesModel.objects.create(
                dates=(date_1, date_2),
                dates_inner=(date_1, date_2.replace(day=5)),
            )
        RangesModel.objects.create(
            dates=(date_1, date_2),
            dates_inner=(date_1, date_2),
        )

    def test_check_constraint_datetimerange_contains(self):
        constraint_name = 'timestamps_contains'
        self.assertNotIn(constraint_name, self.get_constraints(RangesModel._meta.db_table))
        constraint = CheckConstraint(
            check=Q(timestamps__contains=F('timestamps_inner')),
            name=constraint_name,
        )
        with connection.schema_editor() as editor:
            editor.add_constraint(RangesModel, constraint)
        self.assertIn(constraint_name, self.get_constraints(RangesModel._meta.db_table))
        datetime_1 = datetime.datetime(2016, 1, 1)
        datetime_2 = datetime.datetime(2016, 1, 2, 12)
        with self.assertRaises(IntegrityError), transaction.atomic():
            RangesModel.objects.create(
                timestamps=(datetime_1, datetime_2),
                timestamps_inner=(datetime_1, datetime_2.replace(hour=13)),
            )
        RangesModel.objects.create(
            timestamps=(datetime_1, datetime_2),
            timestamps_inner=(datetime_1, datetime_2),
        )

    def test_opclass(self):
        constraint = UniqueConstraint(
            name='test_opclass',
            fields=['scene'],
            opclasses=['varchar_pattern_ops'],
        )
        with connection.schema_editor() as editor:
            editor.add_constraint(Scene, constraint)
        self.assertIn(constraint.name, self.get_constraints(Scene._meta.db_table))
        with editor.connection.cursor() as cursor:
            cursor.execute(self.get_opclass_query, [constraint.name])
            self.assertEqual(
                cursor.fetchall(),
                [('varchar_pattern_ops', constraint.name)],
            )
        # Drop the constraint.
        with connection.schema_editor() as editor:
            editor.remove_constraint(Scene, constraint)
        self.assertNotIn(constraint.name, self.get_constraints(Scene._meta.db_table))

    def test_opclass_multiple_columns(self):
        constraint = UniqueConstraint(
            name='test_opclass_multiple',
            fields=['scene', 'setting'],
            opclasses=['varchar_pattern_ops', 'text_pattern_ops'],
        )
        with connection.schema_editor() as editor:
            editor.add_constraint(Scene, constraint)
        with editor.connection.cursor() as cursor:
            cursor.execute(self.get_opclass_query, [constraint.name])
            expected_opclasses = (
                ('varchar_pattern_ops', constraint.name),
                ('text_pattern_ops', constraint.name),
            )
            self.assertCountEqual(cursor.fetchall(), expected_opclasses)

    def test_opclass_partial(self):
        constraint = UniqueConstraint(
            name='test_opclass_partial',
            fields=['scene'],
            opclasses=['varchar_pattern_ops'],
            condition=Q(setting__contains="Sir Bedemir's Castle"),
        )
        with connection.schema_editor() as editor:
            editor.add_constraint(Scene, constraint)
        with editor.connection.cursor() as cursor:
            cursor.execute(self.get_opclass_query, [constraint.name])
            self.assertCountEqual(
                cursor.fetchall(),
                [('varchar_pattern_ops', constraint.name)],
            )

    @skipUnlessDBFeature('supports_covering_indexes')
    def test_opclass_include(self):
        constraint = UniqueConstraint(
            name='test_opclass_include',
            fields=['scene'],
            opclasses=['varchar_pattern_ops'],
            include=['setting'],
        )
        with connection.schema_editor() as editor:
            editor.add_constraint(Scene, constraint)
        with editor.connection.cursor() as cursor:
            cursor.execute(self.get_opclass_query, [constraint.name])
            self.assertCountEqual(
                cursor.fetchall(),
                [('varchar_pattern_ops', constraint.name)],
            )

    @skipUnlessDBFeature('supports_expression_indexes')
    def test_opclass_func(self):
        constraint = UniqueConstraint(
            OpClass(Lower('scene'), name='text_pattern_ops'),
            name='test_opclass_func',
        )
        with connection.schema_editor() as editor:
            editor.add_constraint(Scene, constraint)
        constraints = self.get_constraints(Scene._meta.db_table)
        self.assertIs(constraints[constraint.name]['unique'], True)
        self.assertIn(constraint.name, constraints)
        with editor.connection.cursor() as cursor:
            cursor.execute(self.get_opclass_query, [constraint.name])
            self.assertEqual(
                cursor.fetchall(),
                [('text_pattern_ops', constraint.name)],
            )
        Scene.objects.create(scene='Scene 10', setting='The dark forest of Ewing')
        with self.assertRaises(IntegrityError), transaction.atomic():
            Scene.objects.create(scene='ScEnE 10', setting="Sir Bedemir's Castle")
        Scene.objects.create(scene='Scene 5', setting="Sir Bedemir's Castle")
        # Drop the constraint.
        with connection.schema_editor() as editor:
            editor.remove_constraint(Scene, constraint)
        self.assertNotIn(constraint.name, self.get_constraints(Scene._meta.db_table))
        Scene.objects.create(scene='ScEnE 10', setting="Sir Bedemir's Castle")


class ExclusionConstraintTests(PostgreSQLTestCase):
    def get_constraints(self, table):
        """Get the constraints on the table using a new cursor."""
        with connection.cursor() as cursor:
            return connection.introspection.get_constraints(cursor, table)

    def test_invalid_condition(self):
        msg = 'ExclusionConstraint.condition must be a Q instance.'
        with self.assertRaisesMessage(ValueError, msg):
            ExclusionConstraint(
                index_type='GIST',
                name='exclude_invalid_condition',
                expressions=[(F('datespan'), RangeOperators.OVERLAPS)],
                condition=F('invalid'),
            )

    def test_invalid_index_type(self):
        msg = 'Exclusion constraints only support GiST or SP-GiST indexes.'
        with self.assertRaisesMessage(ValueError, msg):
            ExclusionConstraint(
                index_type='gin',
                name='exclude_invalid_index_type',
                expressions=[(F('datespan'), RangeOperators.OVERLAPS)],
            )

    def test_invalid_expressions(self):
        msg = 'The expressions must be a list of 2-tuples.'
        for expressions in (['foo'], [('foo')], [('foo_1', 'foo_2', 'foo_3')]):
            with self.subTest(expressions), self.assertRaisesMessage(ValueError, msg):
                ExclusionConstraint(
                    index_type='GIST',
                    name='exclude_invalid_expressions',
                    expressions=expressions,
                )

    def test_empty_expressions(self):
        msg = 'At least one expression is required to define an exclusion constraint.'
        for empty_expressions in (None, []):
            with self.subTest(empty_expressions), self.assertRaisesMessage(ValueError, msg):
                ExclusionConstraint(
                    index_type='GIST',
                    name='exclude_empty_expressions',
                    expressions=empty_expressions,
                )

    def test_invalid_deferrable(self):
        msg = 'ExclusionConstraint.deferrable must be a Deferrable instance.'
        with self.assertRaisesMessage(ValueError, msg):
            ExclusionConstraint(
                name='exclude_invalid_deferrable',
                expressions=[(F('datespan'), RangeOperators.OVERLAPS)],
                deferrable='invalid',
            )

    def test_deferrable_with_condition(self):
        msg = 'ExclusionConstraint with conditions cannot be deferred.'
        with self.assertRaisesMessage(ValueError, msg):
            ExclusionConstraint(
                name='exclude_invalid_condition',
                expressions=[(F('datespan'), RangeOperators.OVERLAPS)],
                condition=Q(cancelled=False),
                deferrable=Deferrable.DEFERRED,
            )

    def test_invalid_include_type(self):
        msg = 'ExclusionConstraint.include must be a list or tuple.'
        with self.assertRaisesMessage(ValueError, msg):
            ExclusionConstraint(
                name='exclude_invalid_include',
                expressions=[(F('datespan'), RangeOperators.OVERLAPS)],
                include='invalid',
            )

    def test_invalid_include_index_type(self):
        msg = 'Covering exclusion constraints only support GiST indexes.'
        with self.assertRaisesMessage(ValueError, msg):
            ExclusionConstraint(
                name='exclude_invalid_index_type',
                expressions=[(F('datespan'), RangeOperators.OVERLAPS)],
                include=['cancelled'],
                index_type='spgist',
            )

    def test_invalid_opclasses_type(self):
        msg = 'ExclusionConstraint.opclasses must be a list or tuple.'
        with self.assertRaisesMessage(ValueError, msg):
            ExclusionConstraint(
                name='exclude_invalid_opclasses',
                expressions=[(F('datespan'), RangeOperators.OVERLAPS)],
                opclasses='invalid',
            )

    def test_opclasses_and_expressions_same_length(self):
        msg = (
            'ExclusionConstraint.expressions and '
            'ExclusionConstraint.opclasses must have the same number of '
            'elements.'
        )
        with self.assertRaisesMessage(ValueError, msg):
            ExclusionConstraint(
                name='exclude_invalid_expressions_opclasses_length',
                expressions=[(F('datespan'), RangeOperators.OVERLAPS)],
                opclasses=['foo', 'bar'],
            )

    def test_repr(self):
        constraint = ExclusionConstraint(
            name='exclude_overlapping',
            expressions=[
                (F('datespan'), RangeOperators.OVERLAPS),
                (F('room'), RangeOperators.EQUAL),
            ],
        )
        self.assertEqual(
            repr(constraint),
            "<ExclusionConstraint: index_type='GIST' expressions=["
            "(F(datespan), '&&'), (F(room), '=')] name='exclude_overlapping'>",
        )
        constraint = ExclusionConstraint(
            name='exclude_overlapping',
            expressions=[(F('datespan'), RangeOperators.ADJACENT_TO)],
            condition=Q(cancelled=False),
            index_type='SPGiST',
        )
        self.assertEqual(
            repr(constraint),
            "<ExclusionConstraint: index_type='SPGiST' expressions=["
            "(F(datespan), '-|-')] name='exclude_overlapping' "
            "condition=(AND: ('cancelled', False))>",
        )
        constraint = ExclusionConstraint(
            name='exclude_overlapping',
            expressions=[(F('datespan'), RangeOperators.ADJACENT_TO)],
            deferrable=Deferrable.IMMEDIATE,
        )
        self.assertEqual(
            repr(constraint),
            "<ExclusionConstraint: index_type='GIST' expressions=["
            "(F(datespan), '-|-')] name='exclude_overlapping' "
            "deferrable=Deferrable.IMMEDIATE>",
        )
        constraint = ExclusionConstraint(
            name='exclude_overlapping',
            expressions=[(F('datespan'), RangeOperators.ADJACENT_TO)],
            include=['cancelled', 'room'],
        )
        self.assertEqual(
            repr(constraint),
            "<ExclusionConstraint: index_type='GIST' expressions=["
            "(F(datespan), '-|-')] name='exclude_overlapping' "
            "include=('cancelled', 'room')>",
        )
        constraint = ExclusionConstraint(
            name='exclude_overlapping',
            expressions=[(F('datespan'), RangeOperators.ADJACENT_TO)],
            opclasses=['range_ops'],
        )
        self.assertEqual(
            repr(constraint),
            "<ExclusionConstraint: index_type='GIST' expressions=["
            "(F(datespan), '-|-')] name='exclude_overlapping' "
            "opclasses=['range_ops']>",
        )

    def test_eq(self):
        constraint_1 = ExclusionConstraint(
            name='exclude_overlapping',
            expressions=[
                (F('datespan'), RangeOperators.OVERLAPS),
                (F('room'), RangeOperators.EQUAL),
            ],
            condition=Q(cancelled=False),
        )
        constraint_2 = ExclusionConstraint(
            name='exclude_overlapping',
            expressions=[
                ('datespan', RangeOperators.OVERLAPS),
                ('room', RangeOperators.EQUAL),
            ],
        )
        constraint_3 = ExclusionConstraint(
            name='exclude_overlapping',
            expressions=[('datespan', RangeOperators.OVERLAPS)],
            condition=Q(cancelled=False),
        )
        constraint_4 = ExclusionConstraint(
            name='exclude_overlapping',
            expressions=[
                ('datespan', RangeOperators.OVERLAPS),
                ('room', RangeOperators.EQUAL),
            ],
            deferrable=Deferrable.DEFERRED,
        )
        constraint_5 = ExclusionConstraint(
            name='exclude_overlapping',
            expressions=[
                ('datespan', RangeOperators.OVERLAPS),
                ('room', RangeOperators.EQUAL),
            ],
            deferrable=Deferrable.IMMEDIATE,
        )
        constraint_6 = ExclusionConstraint(
            name='exclude_overlapping',
            expressions=[
                ('datespan', RangeOperators.OVERLAPS),
                ('room', RangeOperators.EQUAL),
            ],
            deferrable=Deferrable.IMMEDIATE,
            include=['cancelled'],
        )
        constraint_7 = ExclusionConstraint(
            name='exclude_overlapping',
            expressions=[
                ('datespan', RangeOperators.OVERLAPS),
                ('room', RangeOperators.EQUAL),
            ],
            include=['cancelled'],
        )
        constraint_8 = ExclusionConstraint(
            name='exclude_overlapping',
            expressions=[
                ('datespan', RangeOperators.OVERLAPS),
                ('room', RangeOperators.EQUAL),
            ],
            include=['cancelled'],
            opclasses=['range_ops', 'range_ops']
        )
        constraint_9 = ExclusionConstraint(
            name='exclude_overlapping',
            expressions=[
                ('datespan', RangeOperators.OVERLAPS),
                ('room', RangeOperators.EQUAL),
            ],
            opclasses=['range_ops', 'range_ops']
        )
        self.assertEqual(constraint_1, constraint_1)
        self.assertEqual(constraint_1, mock.ANY)
        self.assertNotEqual(constraint_1, constraint_2)
        self.assertNotEqual(constraint_1, constraint_3)
        self.assertNotEqual(constraint_1, constraint_4)
        self.assertNotEqual(constraint_2, constraint_3)
        self.assertNotEqual(constraint_2, constraint_4)
        self.assertNotEqual(constraint_2, constraint_7)
        self.assertNotEqual(constraint_2, constraint_9)
        self.assertNotEqual(constraint_4, constraint_5)
        self.assertNotEqual(constraint_5, constraint_6)
        self.assertNotEqual(constraint_7, constraint_8)
        self.assertNotEqual(constraint_1, object())

    def test_deconstruct(self):
        constraint = ExclusionConstraint(
            name='exclude_overlapping',
            expressions=[('datespan', RangeOperators.OVERLAPS), ('room', RangeOperators.EQUAL)],
        )
        path, args, kwargs = constraint.deconstruct()
        self.assertEqual(path, 'django.contrib.postgres.constraints.ExclusionConstraint')
        self.assertEqual(args, ())
        self.assertEqual(kwargs, {
            'name': 'exclude_overlapping',
            'expressions': [('datespan', RangeOperators.OVERLAPS), ('room', RangeOperators.EQUAL)],
        })

    def test_deconstruct_index_type(self):
        constraint = ExclusionConstraint(
            name='exclude_overlapping',
            index_type='SPGIST',
            expressions=[('datespan', RangeOperators.OVERLAPS), ('room', RangeOperators.EQUAL)],
        )
        path, args, kwargs = constraint.deconstruct()
        self.assertEqual(path, 'django.contrib.postgres.constraints.ExclusionConstraint')
        self.assertEqual(args, ())
        self.assertEqual(kwargs, {
            'name': 'exclude_overlapping',
            'index_type': 'SPGIST',
            'expressions': [('datespan', RangeOperators.OVERLAPS), ('room', RangeOperators.EQUAL)],
        })

    def test_deconstruct_condition(self):
        constraint = ExclusionConstraint(
            name='exclude_overlapping',
            expressions=[('datespan', RangeOperators.OVERLAPS), ('room', RangeOperators.EQUAL)],
            condition=Q(cancelled=False),
        )
        path, args, kwargs = constraint.deconstruct()
        self.assertEqual(path, 'django.contrib.postgres.constraints.ExclusionConstraint')
        self.assertEqual(args, ())
        self.assertEqual(kwargs, {
            'name': 'exclude_overlapping',
            'expressions': [('datespan', RangeOperators.OVERLAPS), ('room', RangeOperators.EQUAL)],
            'condition': Q(cancelled=False),
        })

    def test_deconstruct_deferrable(self):
        constraint = ExclusionConstraint(
            name='exclude_overlapping',
            expressions=[('datespan', RangeOperators.OVERLAPS)],
            deferrable=Deferrable.DEFERRED,
        )
        path, args, kwargs = constraint.deconstruct()
        self.assertEqual(path, 'django.contrib.postgres.constraints.ExclusionConstraint')
        self.assertEqual(args, ())
        self.assertEqual(kwargs, {
            'name': 'exclude_overlapping',
            'expressions': [('datespan', RangeOperators.OVERLAPS)],
            'deferrable': Deferrable.DEFERRED,
        })

    def test_deconstruct_include(self):
        constraint = ExclusionConstraint(
            name='exclude_overlapping',
            expressions=[('datespan', RangeOperators.OVERLAPS)],
            include=['cancelled', 'room'],
        )
        path, args, kwargs = constraint.deconstruct()
        self.assertEqual(path, 'django.contrib.postgres.constraints.ExclusionConstraint')
        self.assertEqual(args, ())
        self.assertEqual(kwargs, {
            'name': 'exclude_overlapping',
            'expressions': [('datespan', RangeOperators.OVERLAPS)],
            'include': ('cancelled', 'room'),
        })

    def test_deconstruct_opclasses(self):
        constraint = ExclusionConstraint(
            name='exclude_overlapping',
            expressions=[('datespan', RangeOperators.OVERLAPS)],
            opclasses=['range_ops'],
        )
        path, args, kwargs = constraint.deconstruct()
        self.assertEqual(path, 'django.contrib.postgres.constraints.ExclusionConstraint')
        self.assertEqual(args, ())
        self.assertEqual(kwargs, {
            'name': 'exclude_overlapping',
            'expressions': [('datespan', RangeOperators.OVERLAPS)],
            'opclasses': ['range_ops'],
        })

    def _test_range_overlaps(self, constraint):
        # Create exclusion constraint.
        self.assertNotIn(constraint.name, self.get_constraints(HotelReservation._meta.db_table))
        with connection.schema_editor() as editor:
            editor.add_constraint(HotelReservation, constraint)
        self.assertIn(constraint.name, self.get_constraints(HotelReservation._meta.db_table))
        # Add initial reservations.
        room101 = Room.objects.create(number=101)
        room102 = Room.objects.create(number=102)
        datetimes = [
            timezone.datetime(2018, 6, 20),
            timezone.datetime(2018, 6, 24),
            timezone.datetime(2018, 6, 26),
            timezone.datetime(2018, 6, 28),
            timezone.datetime(2018, 6, 29),
        ]
        HotelReservation.objects.create(
            datespan=DateRange(datetimes[0].date(), datetimes[1].date()),
            start=datetimes[0],
            end=datetimes[1],
            room=room102,
        )
        HotelReservation.objects.create(
            datespan=DateRange(datetimes[1].date(), datetimes[3].date()),
            start=datetimes[1],
            end=datetimes[3],
            room=room102,
        )
        # Overlap dates.
        with self.assertRaises(IntegrityError), transaction.atomic():
            reservation = HotelReservation(
                datespan=(datetimes[1].date(), datetimes[2].date()),
                start=datetimes[1],
                end=datetimes[2],
                room=room102,
            )
            reservation.save()
        # Valid range.
        HotelReservation.objects.bulk_create([
            # Other room.
            HotelReservation(
                datespan=(datetimes[1].date(), datetimes[2].date()),
                start=datetimes[1],
                end=datetimes[2],
                room=room101,
            ),
            # Cancelled reservation.
            HotelReservation(
                datespan=(datetimes[1].date(), datetimes[1].date()),
                start=datetimes[1],
                end=datetimes[2],
                room=room102,
                cancelled=True,
            ),
            # Other adjacent dates.
            HotelReservation(
                datespan=(datetimes[3].date(), datetimes[4].date()),
                start=datetimes[3],
                end=datetimes[4],
                room=room102,
            ),
        ])

    def test_range_overlaps_custom(self):
        class TsTzRange(Func):
            function = 'TSTZRANGE'
            output_field = DateTimeRangeField()

        constraint = ExclusionConstraint(
            name='exclude_overlapping_reservations_custom',
            expressions=[
                (TsTzRange('start', 'end', RangeBoundary()), RangeOperators.OVERLAPS),
                ('room', RangeOperators.EQUAL)
            ],
            condition=Q(cancelled=False),
            opclasses=['range_ops', 'gist_int4_ops'],
        )
        self._test_range_overlaps(constraint)

    def test_range_overlaps(self):
        constraint = ExclusionConstraint(
            name='exclude_overlapping_reservations',
            expressions=[
                (F('datespan'), RangeOperators.OVERLAPS),
                ('room', RangeOperators.EQUAL)
            ],
            condition=Q(cancelled=False),
        )
        self._test_range_overlaps(constraint)

    def test_range_adjacent(self):
        constraint_name = 'ints_adjacent'
        self.assertNotIn(constraint_name, self.get_constraints(RangesModel._meta.db_table))
        constraint = ExclusionConstraint(
            name=constraint_name,
            expressions=[('ints', RangeOperators.ADJACENT_TO)],
        )
        with connection.schema_editor() as editor:
            editor.add_constraint(RangesModel, constraint)
        self.assertIn(constraint_name, self.get_constraints(RangesModel._meta.db_table))
        RangesModel.objects.create(ints=(20, 50))
        with self.assertRaises(IntegrityError), transaction.atomic():
            RangesModel.objects.create(ints=(10, 20))
        RangesModel.objects.create(ints=(10, 19))
        RangesModel.objects.create(ints=(51, 60))
        # Drop the constraint.
        with connection.schema_editor() as editor:
            editor.remove_constraint(RangesModel, constraint)
        self.assertNotIn(constraint_name, self.get_constraints(RangesModel._meta.db_table))

    def test_expressions_with_params(self):
        constraint_name = 'scene_left_equal'
        self.assertNotIn(constraint_name, self.get_constraints(Scene._meta.db_table))
        constraint = ExclusionConstraint(
            name=constraint_name,
            expressions=[(Left('scene', 4), RangeOperators.EQUAL)],
        )
        with connection.schema_editor() as editor:
            editor.add_constraint(Scene, constraint)
        self.assertIn(constraint_name, self.get_constraints(Scene._meta.db_table))

    def test_expressions_with_key_transform(self):
        constraint_name = 'exclude_overlapping_reservations_smoking'
        constraint = ExclusionConstraint(
            name=constraint_name,
            expressions=[
                (F('datespan'), RangeOperators.OVERLAPS),
                (KeyTextTransform('smoking', 'requirements'), RangeOperators.EQUAL),
            ],
        )
        with connection.schema_editor() as editor:
            editor.add_constraint(HotelReservation, constraint)
        self.assertIn(
            constraint_name,
            self.get_constraints(HotelReservation._meta.db_table),
        )

    def test_index_transform(self):
        constraint_name = 'first_index_equal'
        constraint = ExclusionConstraint(
            name=constraint_name,
            expressions=[('field__0', RangeOperators.EQUAL)],
        )
        with connection.schema_editor() as editor:
            editor.add_constraint(IntegerArrayModel, constraint)
        self.assertIn(
            constraint_name,
            self.get_constraints(IntegerArrayModel._meta.db_table),
        )

    def test_range_adjacent_initially_deferred(self):
        constraint_name = 'ints_adjacent_deferred'
        self.assertNotIn(constraint_name, self.get_constraints(RangesModel._meta.db_table))
        constraint = ExclusionConstraint(
            name=constraint_name,
            expressions=[('ints', RangeOperators.ADJACENT_TO)],
            deferrable=Deferrable.DEFERRED,
        )
        with connection.schema_editor() as editor:
            editor.add_constraint(RangesModel, constraint)
        self.assertIn(constraint_name, self.get_constraints(RangesModel._meta.db_table))
        RangesModel.objects.create(ints=(20, 50))
        adjacent_range = RangesModel.objects.create(ints=(10, 20))
        # Constraint behavior can be changed with SET CONSTRAINTS.
        with self.assertRaises(IntegrityError):
            with transaction.atomic(), connection.cursor() as cursor:
                quoted_name = connection.ops.quote_name(constraint_name)
                cursor.execute('SET CONSTRAINTS %s IMMEDIATE' % quoted_name)
        # Remove adjacent range before the end of transaction.
        adjacent_range.delete()
        RangesModel.objects.create(ints=(10, 19))
        RangesModel.objects.create(ints=(51, 60))

    @skipUnlessDBFeature('supports_covering_gist_indexes')
    def test_range_adjacent_include(self):
        constraint_name = 'ints_adjacent_include'
        self.assertNotIn(constraint_name, self.get_constraints(RangesModel._meta.db_table))
        constraint = ExclusionConstraint(
            name=constraint_name,
            expressions=[('ints', RangeOperators.ADJACENT_TO)],
            include=['decimals', 'ints'],
            index_type='gist',
        )
        with connection.schema_editor() as editor:
            editor.add_constraint(RangesModel, constraint)
        self.assertIn(constraint_name, self.get_constraints(RangesModel._meta.db_table))
        RangesModel.objects.create(ints=(20, 50))
        with self.assertRaises(IntegrityError), transaction.atomic():
            RangesModel.objects.create(ints=(10, 20))
        RangesModel.objects.create(ints=(10, 19))
        RangesModel.objects.create(ints=(51, 60))

    @skipUnlessDBFeature('supports_covering_gist_indexes')
    def test_range_adjacent_include_condition(self):
        constraint_name = 'ints_adjacent_include_condition'
        self.assertNotIn(constraint_name, self.get_constraints(RangesModel._meta.db_table))
        constraint = ExclusionConstraint(
            name=constraint_name,
            expressions=[('ints', RangeOperators.ADJACENT_TO)],
            include=['decimals'],
            condition=Q(id__gte=100),
        )
        with connection.schema_editor() as editor:
            editor.add_constraint(RangesModel, constraint)
        self.assertIn(constraint_name, self.get_constraints(RangesModel._meta.db_table))

    @skipUnlessDBFeature('supports_covering_gist_indexes')
    def test_range_adjacent_include_deferrable(self):
        constraint_name = 'ints_adjacent_include_deferrable'
        self.assertNotIn(constraint_name, self.get_constraints(RangesModel._meta.db_table))
        constraint = ExclusionConstraint(
            name=constraint_name,
            expressions=[('ints', RangeOperators.ADJACENT_TO)],
            include=['decimals'],
            deferrable=Deferrable.DEFERRED,
        )
        with connection.schema_editor() as editor:
            editor.add_constraint(RangesModel, constraint)
        self.assertIn(constraint_name, self.get_constraints(RangesModel._meta.db_table))

    def test_include_not_supported(self):
        constraint_name = 'ints_adjacent_include_not_supported'
        constraint = ExclusionConstraint(
            name=constraint_name,
            expressions=[('ints', RangeOperators.ADJACENT_TO)],
            include=['id'],
        )
        msg = 'Covering exclusion constraints requires PostgreSQL 12+.'
        with connection.schema_editor() as editor:
            with mock.patch(
                'django.db.backends.postgresql.features.DatabaseFeatures.supports_covering_gist_indexes',
                False,
            ):
                with self.assertRaisesMessage(NotSupportedError, msg):
                    editor.add_constraint(RangesModel, constraint)

    def test_range_adjacent_opclasses(self):
        constraint_name = 'ints_adjacent_opclasses'
        self.assertNotIn(constraint_name, self.get_constraints(RangesModel._meta.db_table))
        constraint = ExclusionConstraint(
            name=constraint_name,
            expressions=[('ints', RangeOperators.ADJACENT_TO)],
            opclasses=['range_ops'],
        )
        with connection.schema_editor() as editor:
            editor.add_constraint(RangesModel, constraint)
        self.assertIn(constraint_name, self.get_constraints(RangesModel._meta.db_table))
        RangesModel.objects.create(ints=(20, 50))
        with self.assertRaises(IntegrityError), transaction.atomic():
            RangesModel.objects.create(ints=(10, 20))
        RangesModel.objects.create(ints=(10, 19))
        RangesModel.objects.create(ints=(51, 60))
        # Drop the constraint.
        with connection.schema_editor() as editor:
            editor.remove_constraint(RangesModel, constraint)
        self.assertNotIn(constraint_name, self.get_constraints(RangesModel._meta.db_table))

    def test_range_adjacent_opclasses_condition(self):
        constraint_name = 'ints_adjacent_opclasses_condition'
        self.assertNotIn(constraint_name, self.get_constraints(RangesModel._meta.db_table))
        constraint = ExclusionConstraint(
            name=constraint_name,
            expressions=[('ints', RangeOperators.ADJACENT_TO)],
            opclasses=['range_ops'],
            condition=Q(id__gte=100),
        )
        with connection.schema_editor() as editor:
            editor.add_constraint(RangesModel, constraint)
        self.assertIn(constraint_name, self.get_constraints(RangesModel._meta.db_table))

    def test_range_adjacent_opclasses_deferrable(self):
        constraint_name = 'ints_adjacent_opclasses_deferrable'
        self.assertNotIn(constraint_name, self.get_constraints(RangesModel._meta.db_table))
        constraint = ExclusionConstraint(
            name=constraint_name,
            expressions=[('ints', RangeOperators.ADJACENT_TO)],
            opclasses=['range_ops'],
            deferrable=Deferrable.DEFERRED,
        )
        with connection.schema_editor() as editor:
            editor.add_constraint(RangesModel, constraint)
        self.assertIn(constraint_name, self.get_constraints(RangesModel._meta.db_table))

    @skipUnlessDBFeature('supports_covering_gist_indexes')
    def test_range_adjacent_opclasses_include(self):
        constraint_name = 'ints_adjacent_opclasses_include'
        self.assertNotIn(constraint_name, self.get_constraints(RangesModel._meta.db_table))
        constraint = ExclusionConstraint(
            name=constraint_name,
            expressions=[('ints', RangeOperators.ADJACENT_TO)],
            opclasses=['range_ops'],
            include=['decimals'],
        )
        with connection.schema_editor() as editor:
            editor.add_constraint(RangesModel, constraint)
        self.assertIn(constraint_name, self.get_constraints(RangesModel._meta.db_table))

    def test_range_equal_cast(self):
        constraint_name = 'exclusion_equal_room_cast'
        self.assertNotIn(constraint_name, self.get_constraints(Room._meta.db_table))
        constraint = ExclusionConstraint(
            name=constraint_name,
            expressions=[(Cast('number', IntegerField()), RangeOperators.EQUAL)],
        )
        with connection.schema_editor() as editor:
            editor.add_constraint(Room, constraint)
        self.assertIn(constraint_name, self.get_constraints(Room._meta.db_table))
