from unittest import skipUnless

from django.db import connection, connections

from django.test import TestCase

@skipUnless(connection.vendor == "mysql", "MySQL tests")

class ParsingTests(TestCase):

    def test_parse_constraint_columns(self):

        _parse_constraint_columns = connection.introspection._parse_constraint_columns

        tests = (

            ("`height` >= 0", ["height"], ["height"]),

            ("`cost` BETWEEN 1 AND 10", ["cost"], ["cost"]),

            ("`ref1` > `ref2`", ["id", "ref1", "ref2"], ["ref1", "ref2"]),

            (

                "`start` IS NULL OR `end` IS NULL OR `start` < `end`",

                ["id", "start", "end"],

                ["start", "end"],

            ),

            ("JSON_VALID(`json_field`)", ["json_field"], ["json_field"]),

            ("CHAR_LENGTH(`name`) > 2", ["name"], ["name"]),

            ("lower(`ref1`) != 'test'", ["id", "owe", "ref1"], ["ref1"]),

            ("lower(`ref1`) != 'test'", ["id", "lower", "ref1"], ["ref1"]),

            ("`name` LIKE 'test%'", ["name"], ["name"]),

        )

        for check_clause, table_columns, expected_columns in tests:

            with self.subTest(check_clause):

                check_columns = _parse_constraint_columns(check_clause, table_columns)

                self.assertEqual(list(check_columns), expected_columns)

@skipUnless(connection.vendor == "mysql", "MySQL tests")

class StorageEngineTests(TestCase):

    databases = {"default", "other"}

    def test_get_storage_engine(self):

        table_name = "test_storage_engine"

        create_sql = "CREATE TABLE %s (id INTEGER) ENGINE = %%s" % table_name

        drop_sql = "DROP TABLE %s" % table_name

        default_connection = connections["default"]

        other_connection = connections["other"]

        try:

            with default_connection.cursor() as cursor:

                cursor.execute(create_sql % "InnoDB")

                self.assertEqual(

                    default_connection.introspection.get_storage_engine(

                        cursor, table_name

                    ),

                    "InnoDB",

                )

            with other_connection.cursor() as cursor:

                cursor.execute(create_sql % "MyISAM")

                self.assertEqual(

                    other_connection.introspection.get_storage_engine(

                        cursor, table_name

                    ),

                    "MyISAM",

                )

        finally:

            with default_connection.cursor() as cursor:

                cursor.execute(drop_sql)

            with other_connection.cursor() as cursor:

                cursor.execute(drop_sql)