import re
import threading
import unittest

from django.core.exceptions import ImproperlyConfigured
from django.db import connection
from django.db.models import Avg, StdDev, Sum, Variance
from django.test import (
    TestCase, TransactionTestCase, override_settings, skipUnlessDBFeature,
)

from ..models import Item, Object, Square


@unittest.skipUnless(connection.vendor == 'sqlite', 'SQLite tests')
class Tests(TestCase):
    longMessage = True

    def test_autoincrement(self):
        """
        auto_increment fields are created with the AUTOINCREMENT keyword
        in order to be monotonically increasing (#10164).
        """
        with connection.schema_editor(collect_sql=True) as editor:
            editor.create_model(Square)
            statements = editor.collected_sql
        match = re.search('"id" ([^,]+),', statements[0])
        self.assertIsNotNone(match)
        self.assertEqual(
            'integer NOT NULL PRIMARY KEY AUTOINCREMENT',
            match.group(1),
            'Wrong SQL used to create an auto-increment column on SQLite'
        )

    def test_aggregation(self):
        """
        Raise NotImplementedError when aggregating on date/time fields (#19360).
        """
        for aggregate in (Sum, Avg, Variance, StdDev):
            with self.assertRaises(NotImplementedError):
                Item.objects.all().aggregate(aggregate('time'))
            with self.assertRaises(NotImplementedError):
                Item.objects.all().aggregate(aggregate('date'))
            with self.assertRaises(NotImplementedError):
                Item.objects.all().aggregate(aggregate('last_modified'))
            with self.assertRaises(NotImplementedError):
                Item.objects.all().aggregate(
                    **{'complex': aggregate('last_modified') + aggregate('last_modified')}
                )

    def test_memory_db_test_name(self):
        """A named in-memory db should be allowed where supported."""
        from django.db.backends.sqlite3.base import DatabaseWrapper
        settings_dict = {
            'TEST': {
                'NAME': 'file:memorydb_test?mode=memory&cache=shared',
            }
        }
        wrapper = DatabaseWrapper(settings_dict)
        creation = wrapper.creation
        if creation.connection.features.can_share_in_memory_db:
            expected = creation.connection.settings_dict['TEST']['NAME']
            self.assertEqual(creation._get_test_db_name(), expected)
        else:
            msg = (
                "Using a shared memory database with `mode=memory` in the "
                "database name is not supported in your environment, "
                "use `:memory:` instead."
            )
            with self.assertRaisesMessage(ImproperlyConfigured, msg):
                creation._get_test_db_name()


@unittest.skipUnless(connection.vendor == 'sqlite', 'Test only for SQLite')
@override_settings(DEBUG=True)
class LastExecutedQueryTest(TestCase):

    def test_no_interpolation(self):
        # This shouldn't raise an exception (#17158)
        query = "SELECT strftime('%Y', 'now');"
        connection.cursor().execute(query)
        self.assertEqual(connection.queries[-1]['sql'], query)

    def test_parameter_quoting(self):
        # The implementation of last_executed_queries isn't optimal. It's
        # worth testing that parameters are quoted (#14091).
        query = "SELECT %s"
        params = ["\"'\\"]
        connection.cursor().execute(query, params)
        # Note that the single quote is repeated
        substituted = "SELECT '\"''\\'"
        self.assertEqual(connection.queries[-1]['sql'], substituted)

    def test_large_number_of_parameters(self):
        # If SQLITE_MAX_VARIABLE_NUMBER (default = 999) has been changed to be
        # greater than SQLITE_MAX_COLUMN (default = 2000), last_executed_query
        # can hit the SQLITE_MAX_COLUMN limit (#26063).
        cursor = connection.cursor()
        sql = "SELECT MAX(%s)" % ", ".join(["%s"] * 2001)
        params = list(range(2001))
        # This should not raise an exception.
        cursor.db.ops.last_executed_query(cursor.cursor, sql, params)


@unittest.skipUnless(connection.vendor == 'sqlite', 'SQLite tests')
class EscapingChecks(TestCase):
    """
    All tests in this test case are also run with settings.DEBUG=True in
    EscapingChecksDebug test case, to also test CursorDebugWrapper.
    """
    def test_parameter_escaping(self):
        # '%s' escaping support for sqlite3 (#13648).
        cursor = connection.cursor()
        cursor.execute("select strftime('%s', date('now'))")
        response = cursor.fetchall()[0][0]
        # response should be an non-zero integer
        self.assertTrue(int(response))


@unittest.skipUnless(connection.vendor == 'sqlite', 'SQLite tests')
@override_settings(DEBUG=True)
class EscapingChecksDebug(EscapingChecks):
    pass


@unittest.skipUnless(connection.vendor == 'sqlite', 'SQLite tests')
@skipUnlessDBFeature('can_share_in_memory_db')
class ThreadSharing(TransactionTestCase):
    available_apps = ['backends']

    def test_database_sharing_in_threads(self):
        def create_object():
            Object.objects.create()
        create_object()
        thread = threading.Thread(target=create_object)
        thread.start()
        thread.join()
        self.assertEqual(Object.objects.count(), 2)