import datetime
from turbogears.database import session
from transifex.model import Session, session_table

class SQLAlchemyStorage:
    def __init__(self):
        pass

    def load(self, id):
        s = Session.query.get(id)
        if not s:
            return None
        return (s.data, s.expiration_time)

    def delete(self, id=None):
        if id is None:
            id = cherrypy.session.id
        s = Session.query.get(id)
        session.delete(s)
        session.flush()

    def save(self, id, data, expiration_time):
        s = Session.query.get(id)
        if not s:
            s = Session()
        s.id = id
        s.data = data 
        s.expiration_time = expiration_time
        session.flush()

    def acquire_lock(self):
        pass

    def release_lock(self):
        pass

    def clean_up(self, sess):
        result = session_table.delete(
            session_table.c.expiration_time.__lt__(datetime.datetime.now())
            ).execute()