import decimal

from django.core.management.color import no_style
from django.db import NotSupportedError, connection, transaction
from django.db.backends.base.operations import BaseDatabaseOperations
from django.db.models import DurationField, Value
from django.db.models.expressions import Col
from django.test import (
    SimpleTestCase,
    TestCase,
    TransactionTestCase,
    override_settings,
    skipIfDBFeature,
)
from django.utils import timezone

from ..models import Author, Book


class SimpleDatabaseOperationTests(SimpleTestCase):
    may_require_msg = "subclasses of BaseDatabaseOperations may require a %s() method"

    def setUp(self):
        self.ops = BaseDatabaseOperations(connection=connection)

    def test_deferrable_sql(self):
        self.assertEqual(self.ops.deferrable_sql(), "")

    def test_end_transaction_rollback(self):
        self.assertEqual(self.ops.end_transaction_sql(success=False), "ROLLBACK;")

    def test_no_limit_value(self):
        with self.assertRaisesMessage(
            NotImplementedError, self.may_require_msg % "no_limit_value"
        ):
            self.ops.no_limit_value()

    def test_quote_name(self):
        with self.assertRaisesMessage(
            NotImplementedError, self.may_require_msg % "quote_name"
        ):
            self.ops.quote_name("a")

    def test_regex_lookup(self):
        with self.assertRaisesMessage(
            NotImplementedError, self.may_require_msg % "regex_lookup"
        ):
            self.ops.regex_lookup(lookup_type="regex")

    def test_set_time_zone_sql(self):
        self.assertEqual(self.ops.set_time_zone_sql(), "")

    def test_sql_flush(self):
        msg = "subclasses of BaseDatabaseOperations must provide an sql_flush() method"
        with self.assertRaisesMessage(NotImplementedError, msg):
            self.ops.sql_flush(None, None)

    def test_pk_default_value(self):
        self.assertEqual(self.ops.pk_default_value(), "DEFAULT")

    def test_tablespace_sql(self):
        self.assertEqual(self.ops.tablespace_sql(None), "")

    def test_sequence_reset_by_name_sql(self):
        self.assertEqual(self.ops.sequence_reset_by_name_sql(None, []), [])

    def test_adapt_unknown_value_decimal(self):
        value = decimal.Decimal("3.14")
        self.assertEqual(
            self.ops.adapt_unknown_value(value),
            self.ops.adapt_decimalfield_value(value),
        )

    def test_adapt_unknown_value_date(self):
        value = timezone.now().date()
        self.assertEqual(
            self.ops.adapt_unknown_value(value), self.ops.adapt_datefield_value(value)
        )

    def test_adapt_unknown_value_time(self):
        value = timezone.now().time()
        self.assertEqual(
            self.ops.adapt_unknown_value(value), self.ops.adapt_timefield_value(value)
        )

    def test_adapt_timefield_value_none(self):
        self.assertIsNone(self.ops.adapt_timefield_value(None))

    def test_adapt_timefield_value_expression(self):
        value = Value(timezone.now().time())
        self.assertEqual(self.ops.adapt_timefield_value(value), value)

    def test_adapt_datetimefield_value_none(self):
        self.assertIsNone(self.ops.adapt_datetimefield_value(None))

    def test_adapt_datetimefield_value_expression(self):
        value = Value(timezone.now())
        self.assertEqual(self.ops.adapt_datetimefield_value(value), value)

    def test_adapt_timefield_value(self):
        msg = "Django does not support timezone-aware times."
        with self.assertRaisesMessage(ValueError, msg):
            self.ops.adapt_timefield_value(timezone.make_aware(timezone.now()))

    @override_settings(USE_TZ=False)
    def test_adapt_timefield_value_unaware(self):
        now = timezone.now()
        self.assertEqual(self.ops.adapt_timefield_value(now), str(now))

    def test_format_for_duration_arithmetic(self):
        msg = self.may_require_msg % "format_for_duration_arithmetic"
        with self.assertRaisesMessage(NotImplementedError, msg):
            self.ops.format_for_duration_arithmetic(None)

    def test_date_extract_sql(self):
        with self.assertRaisesMessage(
            NotImplementedError, self.may_require_msg % "date_extract_sql"
        ):
            self.ops.date_extract_sql(None, None, None)

    def test_time_extract_sql(self):
        with self.assertRaisesMessage(
            NotImplementedError, self.may_require_msg % "date_extract_sql"
        ):
            self.ops.time_extract_sql(None, None, None)

    def test_date_trunc_sql(self):
        with self.assertRaisesMessage(
            NotImplementedError, self.may_require_msg % "date_trunc_sql"
        ):
            self.ops.date_trunc_sql(None, None, None)

    def test_time_trunc_sql(self):
        with self.assertRaisesMessage(
            NotImplementedError, self.may_require_msg % "time_trunc_sql"
        ):
            self.ops.time_trunc_sql(None, None, None)

    def test_datetime_trunc_sql(self):
        with self.assertRaisesMessage(
            NotImplementedError, self.may_require_msg % "datetime_trunc_sql"
        ):
            self.ops.datetime_trunc_sql(None, None, None, None)

    def test_datetime_cast_date_sql(self):
        with self.assertRaisesMessage(
            NotImplementedError, self.may_require_msg % "datetime_cast_date_sql"
        ):
            self.ops.datetime_cast_date_sql(None, None, None)

    def test_datetime_cast_time_sql(self):
        with self.assertRaisesMessage(
            NotImplementedError, self.may_require_msg % "datetime_cast_time_sql"
        ):
            self.ops.datetime_cast_time_sql(None, None, None)

    def test_datetime_extract_sql(self):
        with self.assertRaisesMessage(
            NotImplementedError, self.may_require_msg % "datetime_extract_sql"
        ):
            self.ops.datetime_extract_sql(None, None, None, None)

    def test_prepare_join_on_clause(self):
        author_table = Author._meta.db_table
        author_id_field = Author._meta.get_field("id")
        book_table = Book._meta.db_table
        book_fk_field = Book._meta.get_field("author")
        lhs_expr, rhs_expr = self.ops.prepare_join_on_clause(
            author_table,
            author_id_field,
            book_table,
            book_fk_field,
        )
        self.assertEqual(lhs_expr, Col(author_table, author_id_field))
        self.assertEqual(rhs_expr, Col(book_table, book_fk_field))


class DatabaseOperationTests(TestCase):
    def setUp(self):
        self.ops = BaseDatabaseOperations(connection=connection)

    @skipIfDBFeature("supports_over_clause")
    def test_window_frame_raise_not_supported_error(self):
        msg = "This backend does not support window expressions."
        with self.assertRaisesMessage(NotSupportedError, msg):
            self.ops.window_frame_rows_start_end()

    @skipIfDBFeature("can_distinct_on_fields")
    def test_distinct_on_fields(self):
        msg = "DISTINCT ON fields is not supported by this database backend"
        with self.assertRaisesMessage(NotSupportedError, msg):
            self.ops.distinct_sql(["a", "b"], None)

    @skipIfDBFeature("supports_temporal_subtraction")
    def test_subtract_temporals(self):
        duration_field = DurationField()
        duration_field_internal_type = duration_field.get_internal_type()
        msg = (
            "This backend does not support %s subtraction."
            % duration_field_internal_type
        )
        with self.assertRaisesMessage(NotSupportedError, msg):
            self.ops.subtract_temporals(duration_field_internal_type, None, None)


class SqlFlushTests(TransactionTestCase):
    available_apps = ["backends"]

    def test_sql_flush_no_tables(self):
        self.assertEqual(connection.ops.sql_flush(no_style(), []), [])

    def test_execute_sql_flush_statements(self):
        with transaction.atomic():
            author = Author.objects.create(name="George Orwell")
            Book.objects.create(author=author)
            author = Author.objects.create(name="Harper Lee")
            Book.objects.create(author=author)
            Book.objects.create(author=author)
            self.assertIs(Author.objects.exists(), True)
            self.assertIs(Book.objects.exists(), True)

        sql_list = connection.ops.sql_flush(
            no_style(),
            [Author._meta.db_table, Book._meta.db_table],
            reset_sequences=True,
            allow_cascade=True,
        )
        connection.ops.execute_sql_flush(sql_list)

        with transaction.atomic():
            self.assertIs(Author.objects.exists(), False)
            self.assertIs(Book.objects.exists(), False)
            if connection.features.supports_sequence_reset:
                author = Author.objects.create(name="F. Scott Fitzgerald")
                self.assertEqual(author.pk, 1)
                book = Book.objects.create(author=author)
                self.assertEqual(book.pk, 1)
