from django.conf import settings

from django.contrib.sessions.models import Session

from django.contrib.sessions.backends.base import SessionBase

from django.core.exceptions import SuspiciousOperation

import datetime

class SessionStore(SessionBase):

    """

    Implements database session store

    """

    def __init__(self, session_key=None):

        super(SessionStore, self).__init__(session_key)

    def load(self):

        try:

            s = Session.objects.get(

                session_key = self.session_key,

                expire_date__gt=datetime.datetime.now()

            )

            return self.decode(s.session_data)

        except (Session.DoesNotExist, SuspiciousOperation):

            # Create a new session_key for extra security.

            self.session_key = self._get_new_session_key()

            self._session_cache = {}

            # Save immediately to minimize collision

            self.save()

            # Ensure the user is notified via a new cookie.

            self.modified = True

            return {}

    def exists(self, session_key):

        try:

            Session.objects.get(session_key=session_key)

        except Session.DoesNotExist:

            return False

        return True

    def save(self):

        Session.objects.create(

            session_key = self.session_key,

            session_data = self.encode(self._session),

            expire_date = datetime.datetime.now() + datetime.timedelta(seconds=settings.SESSION_COOKIE_AGE)

        )

    def delete(self, session_key):

        try:

            Session.objects.get(session_key=session_key).delete()

        except Session.DoesNotExist:

            pass