"""

PostgreSQL database backend for Django.

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

"""

from django.db.backends import BaseDatabaseWrapper, BaseDatabaseFeatures

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

from django.utils.safestring import SafeUnicode

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(SafeUnicode, psycopg2.extensions.QuotedString)

class DatabaseFeatures(BaseDatabaseFeatures):

    needs_datetime_string_cast = 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

class DatabaseWrapper(BaseDatabaseWrapper):

    features = DatabaseFeatures()

    ops = DatabaseOperations()

    operators = {

        'exact': '= %s',

        'iexact': 'ILIKE %s',

        'contains': 'LIKE %s',

        'icontains': 'ILIKE %s',

        'regex': '~ %s',

        'iregex': '~* %s',

        'gt': '> %s',

        'gte': '>= %s',

        'lt': '< %s',

        'lte': '<= %s',

        'startswith': 'LIKE %s',

        'endswith': 'LIKE %s',

        'istartswith': 'ILIKE %s',

        'iendswith': 'ILIKE %s',

    }

    def _cursor(self, settings):

        set_tz = False

        if self.connection is None:

            set_tz = True

            if settings.DATABASE_NAME == '':

                from django.core.exceptions import ImproperlyConfigured

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

            conn_string = "dbname=%s" % settings.DATABASE_NAME

            if settings.DATABASE_USER:

                conn_string = "user=%s %s" % (settings.DATABASE_USER, conn_string)

            if settings.DATABASE_PASSWORD:

                conn_string += " password='%s'" % settings.DATABASE_PASSWORD

            if settings.DATABASE_HOST:

                conn_string += " host=%s" % settings.DATABASE_HOST

            if settings.DATABASE_PORT:

                conn_string += " port=%s" % settings.DATABASE_PORT

            self.connection = Database.connect(conn_string, **self.options)

            self.connection.set_isolation_level(1) # make transactions transparent to all cursors

            self.connection.set_client_encoding('UTF8')

        cursor = self.connection.cursor()

        cursor.tzinfo_factory = None

        if set_tz:

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

        return cursor