"""
Dummy database backend for Django.

Django uses this if the DATABASE_ENGINE setting is empty (None or empty string).

Each of these API functions, except connection.close(), raises
ImproperlyConfigured.
"""

from django.core.exceptions import ImproperlyConfigured
from django.db.backends import *
from django.db.backends.creation import BaseDatabaseCreation

def complain(*args, **kwargs):
    raise ImproperlyConfigured, "You haven't set the DATABASE_ENGINE setting yet."

def ignore(*args, **kwargs):
    pass

class DatabaseError(Exception):
    pass

class IntegrityError(DatabaseError):
    pass

class DatabaseOperations(BaseDatabaseOperations):
    quote_name = complain

class DatabaseClient(BaseDatabaseClient):
    runshell = complain
    
class DatabaseIntrospection(BaseDatabaseIntrospection):
    get_table_list = complain
    get_table_description = complain
    get_relations = complain
    get_indexes = complain
    
class DatabaseWrapper(object):    
    operators = {}
    cursor = complain
    _commit = complain
    _rollback = ignore

    def __init__(self, *args, **kwargs):
        super(DatabaseWrapper, self).__init__(*args, **kwargs)

        self.features = BaseDatabaseFeatures()
        self.ops = DatabaseOperations()
        self.client = DatabaseClient(self)
        self.creation = BaseDatabaseCreation(self)
        self.introspection = DatabaseIntrospection(self)
        self.validation = BaseDatabaseValidation()

    def close(self):
        pass