"""

PostgreSQL database backend for Django.

Requires psycopg 2: http://initd.org/projects/psycopg2

"""

from django.conf import settings

from django.db.backends import *

from django.db.backends.signals import connection_created

from django.db.backends.postgresql.operations import DatabaseOperations as PostgresqlDatabaseOperations

from django.db.backends.postgresql.client import DatabaseClient

from django.db.backends.postgresql.creation import DatabaseCreation

from django.db.backends.postgresql.version import get_version

from django.db.backends.postgresql_psycopg2.introspection import DatabaseIntrospection

from django.utils.safestring import SafeUnicode, SafeString

try:

    import psycopg2 as Database

    import psycopg2.extensions

except ImportError, e:

    from django.core.exceptions import ImproperlyConfigured

    raise ImproperlyConfigured("Error loading psycopg2 module: %s" % e)

DatabaseError = Database.DatabaseError

IntegrityError = Database.IntegrityError

psycopg2.extensions.register_type(psycopg2.extensions.UNICODE)

psycopg2.extensions.register_adapter(SafeString, psycopg2.extensions.QuotedString)

psycopg2.extensions.register_adapter(SafeUnicode, psycopg2.extensions.QuotedString)

class DatabaseFeatures(BaseDatabaseFeatures):

    needs_datetime_string_cast = False

    can_return_id_from_insert = False

class DatabaseOperations(PostgresqlDatabaseOperations):

    def last_executed_query(self, cursor, sql, params):

        # With psycopg2, cursor objects have a "query" attribute that is the

        # exact query sent to the database. See docs here:

        # http://www.initd.org/tracker/psycopg/wiki/psycopg2_documentation#postgresql-status-message-and-executed-query

        return cursor.query

    def return_insert_id(self):

        return "RETURNING %s", ()

class DatabaseWrapper(BaseDatabaseWrapper):

    operators = {

        'exact': '= %s',

        'iexact': '= UPPER(%s)',

        'contains': 'LIKE %s',

        'icontains': 'LIKE UPPER(%s)',

        'regex': '~ %s',

        'iregex': '~* %s',

        'gt': '> %s',

        'gte': '>= %s',

        'lt': '< %s',

        'lte': '<= %s',

        'startswith': 'LIKE %s',

        'endswith': 'LIKE %s',

        'istartswith': 'LIKE UPPER(%s)',

        'iendswith': 'LIKE UPPER(%s)',

    }

    def __init__(self, *args, **kwargs):

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

        self.features = DatabaseFeatures()

        autocommit = self.settings_dict["DATABASE_OPTIONS"].get('autocommit', False)

        self.features.uses_autocommit = autocommit

        self._set_isolation_level(int(not autocommit))

        self.ops = DatabaseOperations()

        self.client = DatabaseClient(self)

        self.creation = DatabaseCreation(self)

        self.introspection = DatabaseIntrospection(self)

        self.validation = BaseDatabaseValidation()

    def _cursor(self):

        set_tz = False

        settings_dict = self.settings_dict

        if self.connection is None:

            set_tz = True

            if settings_dict['DATABASE_NAME'] == '':

                from django.core.exceptions import ImproperlyConfigured

                raise ImproperlyConfigured("You need to specify DATABASE_NAME in your Django settings file.")

            conn_params = {

                'database': settings_dict['DATABASE_NAME'],

            }

            conn_params.update(settings_dict['DATABASE_OPTIONS'])

            if 'autocommit' in conn_params:

                del conn_params['autocommit']

            if settings_dict['DATABASE_USER']:

                conn_params['user'] = settings_dict['DATABASE_USER']

            if settings_dict['DATABASE_PASSWORD']:

                conn_params['password'] = settings_dict['DATABASE_PASSWORD']

            if settings_dict['DATABASE_HOST']:

                conn_params['host'] = settings_dict['DATABASE_HOST']

            if settings_dict['DATABASE_PORT']:

                conn_params['port'] = settings_dict['DATABASE_PORT']

            self.connection = Database.connect(**conn_params)

            self.connection.set_client_encoding('UTF8')

            self.connection.set_isolation_level(self.isolation_level)

            connection_created.send(sender=self.__class__)

        cursor = self.connection.cursor()

        cursor.tzinfo_factory = None

        if set_tz:

            cursor.execute("SET TIME ZONE %s", [settings_dict['TIME_ZONE']])

            if not hasattr(self, '_version'):

                self.__class__._version = get_version(cursor)

            if self._version[0:2] < (8, 0):

                # No savepoint support for earlier version of PostgreSQL.

                self.features.uses_savepoints = False

            if self.features.uses_autocommit:

                if self._version[0:2] < (8, 2):

                    # FIXME: Needs extra code to do reliable model insert

                    # handling, so we forbid it for now.

                    from django.core.exceptions import ImproperlyConfigured

                    raise ImproperlyConfigured("You cannot use autocommit=True with PostgreSQL prior to 8.2 at the moment.")

                else:

                    # FIXME: Eventually we're enable this by default for

                    # versions that support it, but, right now, that's hard to

                    # do without breaking other things (#10509).

                    self.features.can_return_id_from_insert = True

        return cursor

    def _enter_transaction_management(self, managed):

        """

        Switch the isolation level when needing transaction support, so that

        the same transaction is visible across all the queries.

        """

        if self.features.uses_autocommit and managed and not self.isolation_level:

            self._set_isolation_level(1)

    def _leave_transaction_management(self, managed):

        """

        If the normal operating mode is "autocommit", switch back to that when

        leaving transaction management.

        """

        if self.features.uses_autocommit and not managed and self.isolation_level:

            self._set_isolation_level(0)

    def _set_isolation_level(self, level):

        """

        Do all the related feature configurations for changing isolation

        levels. This doesn't touch the uses_autocommit feature, since that

        controls the movement *between* isolation levels.

        """

        assert level in (0, 1)

        try:

            if self.connection is not None:

                self.connection.set_isolation_level(level)

        finally:

            self.isolation_level = level

            self.features.uses_savepoints = bool(level)