import os
import re
import tempfile
import threading
import unittest
from pathlib import Path
from unittest import mock

from django.db import (
    DEFAULT_DB_ALIAS,
    NotSupportedError,
    connection,
    connections,
    transaction,
)
from django.db.models import Aggregate, Avg, StdDev, Sum, Variance
from django.db.utils import ConnectionHandler
from django.test import TestCase, TransactionTestCase, override_settings
from django.test.utils import isolate_apps

from ..models import Item, Object, Square


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

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

    def test_distinct_aggregation(self):
        class DistinctAggregate(Aggregate):
            allow_distinct = True

        aggregate = DistinctAggregate("first", "second", distinct=True)
        msg = (
            "SQLite doesn't support DISTINCT on aggregate functions accepting "
            "multiple arguments."
        )
        with self.assertRaisesMessage(NotSupportedError, msg):
            connection.ops.check_expression_support(aggregate)

    def test_distinct_aggregation_multiple_args_no_distinct(self):
        # Aggregate functions accept multiple arguments when DISTINCT isn't
        # used, e.g. GROUP_CONCAT().
        class DistinctAggregate(Aggregate):
            allow_distinct = True

        aggregate = DistinctAggregate("first", "second", distinct=False)
        connection.ops.check_expression_support(aggregate)

    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",
            }
        }
        creation = DatabaseWrapper(settings_dict).creation
        self.assertEqual(
            creation._get_test_db_name(),
            creation.connection.settings_dict["TEST"]["NAME"],
        )

    def test_regexp_function(self):
        tests = (
            ("test", r"[0-9]+", False),
            ("test", r"[a-z]+", True),
            ("test", None, None),
            (None, r"[a-z]+", None),
            (None, None, None),
        )
        for string, pattern, expected in tests:
            with self.subTest((string, pattern)):
                with connection.cursor() as cursor:
                    cursor.execute("SELECT %s REGEXP %s", [string, pattern])
                    value = cursor.fetchone()[0]
                value = bool(value) if value in {0, 1} else value
                self.assertIs(value, expected)

    def test_pathlib_name(self):
        with tempfile.TemporaryDirectory() as tmp:
            settings_dict = {
                "default": {
                    "ENGINE": "django.db.backends.sqlite3",
                    "NAME": Path(tmp) / "test.db",
                },
            }
            connections = ConnectionHandler(settings_dict)
            connections["default"].ensure_connection()
            connections["default"].close()
            self.assertTrue(os.path.isfile(os.path.join(tmp, "test.db")))

    @mock.patch.object(connection, "get_database_version", return_value=(3, 26))
    def test_check_database_version_supported(self, mocked_get_database_version):
        msg = "SQLite 3.27 or later is required (found 3.26)."
        with self.assertRaisesMessage(NotSupportedError, msg):
            connection.check_database_version_supported()
        self.assertTrue(mocked_get_database_version.called)


@unittest.skipUnless(connection.vendor == "sqlite", "SQLite tests")
@isolate_apps("backends")
class SchemaTests(TransactionTestCase):
    available_apps = ["backends"]

    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[1],
            "Wrong SQL used to create an auto-increment column on SQLite",
        )

    def test_disable_constraint_checking_failure_disallowed(self):
        """
        SQLite schema editor is not usable within an outer transaction if
        foreign key constraint checks are not disabled beforehand.
        """
        msg = (
            "SQLite schema editor cannot be used while foreign key "
            "constraint checks are enabled. Make sure to disable them "
            "before entering a transaction.atomic() context because "
            "SQLite does not support disabling them in the middle of "
            "a multi-statement transaction."
        )
        with self.assertRaisesMessage(NotSupportedError, msg):
            with transaction.atomic(), connection.schema_editor(atomic=True):
                pass

    def test_constraint_checks_disabled_atomic_allowed(self):
        """
        SQLite schema editor is usable within an outer transaction as long as
        foreign key constraints checks are disabled beforehand.
        """

        def constraint_checks_enabled():
            with connection.cursor() as cursor:
                return bool(cursor.execute("PRAGMA foreign_keys").fetchone()[0])

        with connection.constraint_checks_disabled(), transaction.atomic():
            with connection.schema_editor(atomic=True):
                self.assertFalse(constraint_checks_enabled())
            self.assertFalse(constraint_checks_enabled())
        self.assertTrue(constraint_checks_enabled())


@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');"
        with connection.cursor() as cursor:
            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 = ["\"'\\"]
        with connection.cursor() as cursor:
            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).
        with connection.cursor() as 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).
        with connection.cursor() as 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")
class ThreadSharing(TransactionTestCase):
    available_apps = ["backends"]

    def test_database_sharing_in_threads(self):
        thread_connections = []

        def create_object():
            Object.objects.create()
            thread_connections.append(connections[DEFAULT_DB_ALIAS].connection)

        main_connection = connections[DEFAULT_DB_ALIAS].connection
        try:
            create_object()
            thread = threading.Thread(target=create_object)
            thread.start()
            thread.join()
            self.assertEqual(Object.objects.count(), 2)
        finally:
            for conn in thread_connections:
                if conn is not main_connection:
                    conn.close()