from django.db.models import Q

from .models import Team

class TeamPermissionsBackend(object):

    def authenticate(self, username=None, password=None):

        return None

    def get_team_permissions(self, user_obj, obj=None):

        """

        Returns a set of permission strings that this user has through his/her

        team memberships.

        """

        if user_obj.is_anonymous() or obj is not None:

            return set()

        if not hasattr(user_obj, "_team_perm_cache"):

            memberships = Team.objects.filter(

                Q(memberships__user=user_obj),

                Q(memberships__state="manager") | Q(memberships__state="member"),

            )

            perms = memberships.values_list(

                "permissions__content_type__app_label",

                "permissions__codename"

            ).order_by()

            user_obj._team_perm_cache = set(["%s.%s" % (ct, name) for ct, name in perms])

        return user_obj._team_perm_cache

    def has_perm(self, user_obj, perm, obj=None):

        if not user_obj.is_active:

            return False

        return perm in self.get_team_permissions(user_obj, obj)

    # Permissions Backends

    "symposion.teams.backends.TeamPermissionsBackend",

    # Auth backends