import subprocess
import unittest
from io import StringIO
from unittest import mock

from django.db import DatabaseError, connection
from django.db.backends.base.creation import BaseDatabaseCreation
from django.db.backends.mysql.creation import DatabaseCreation
from django.test import SimpleTestCase


@unittest.skipUnless(connection.vendor == 'mysql', 'MySQL tests')
class DatabaseCreationTests(SimpleTestCase):

    def _execute_raise_database_exists(self, cursor, parameters, keepdb=False):
        raise DatabaseError(1007, "Can't create database '%s'; database exists" % parameters['dbname'])

    def _execute_raise_access_denied(self, cursor, parameters, keepdb=False):
        raise DatabaseError(1044, "Access denied for user")

    def patch_test_db_creation(self, execute_create_test_db):
        return mock.patch.object(BaseDatabaseCreation, '_execute_create_test_db', execute_create_test_db)

    @mock.patch('sys.stdout', new_callable=StringIO)
    @mock.patch('sys.stderr', new_callable=StringIO)
    def test_create_test_db_database_exists(self, *mocked_objects):
        # Simulate test database creation raising "database exists"
        creation = DatabaseCreation(connection)
        with self.patch_test_db_creation(self._execute_raise_database_exists):
            with mock.patch('builtins.input', return_value='no'):
                with self.assertRaises(SystemExit):
                    # SystemExit is raised if the user answers "no" to the
                    # prompt asking if it's okay to delete the test database.
                    creation._create_test_db(verbosity=0, autoclobber=False, keepdb=False)
            # "Database exists" shouldn't appear when keepdb is on
            creation._create_test_db(verbosity=0, autoclobber=False, keepdb=True)

    @mock.patch('sys.stdout', new_callable=StringIO)
    @mock.patch('sys.stderr', new_callable=StringIO)
    def test_create_test_db_unexpected_error(self, *mocked_objects):
        # Simulate test database creation raising unexpected error
        creation = DatabaseCreation(connection)
        with self.patch_test_db_creation(self._execute_raise_access_denied):
            with self.assertRaises(SystemExit):
                creation._create_test_db(verbosity=0, autoclobber=False, keepdb=False)

    def test_clone_test_db_database_exists(self):
        creation = DatabaseCreation(connection)
        with self.patch_test_db_creation(self._execute_raise_database_exists):
            with mock.patch.object(DatabaseCreation, '_clone_db') as _clone_db:
                creation._clone_test_db('suffix', verbosity=0, keepdb=True)
                _clone_db.assert_not_called()

    def test_clone_test_db_options_ordering(self):
        creation = DatabaseCreation(connection)
        try:
            saved_settings = connection.settings_dict
            connection.settings_dict = {
                'NAME': 'source_db',
                'USER': '',
                'PASSWORD': '',
                'PORT': '',
                'HOST': '',
                'ENGINE': 'django.db.backends.mysql',
                'OPTIONS': {
                    'read_default_file': 'my.cnf',
                },
            }
            with mock.patch.object(subprocess, 'Popen') as mocked_popen:
                creation._clone_db('source_db', 'target_db')
                mocked_popen.assert_has_calls([
                    mock.call(
                        [
                            'mysqldump',
                            '--defaults-file=my.cnf',
                            '--routines',
                            '--events',
                            'source_db',
                        ],
                        stdout=subprocess.PIPE,
                        env=None,
                    ),
                ])
        finally:
            connection.settings_dict = saved_settings
