#!/usr/bin/env python
# -*- coding: utf-8 -*-
# Copyright (C) 2010-2013 Étienne Loks  <etienne.loks_AT_peacefrogsDOTnet>

# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as
# published by the Free Software Foundation, either version 3 of the
# License, or (at your option) any later version.

# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU Affero General Public License for more details.

# You should have received a copy of the GNU Affero General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

# See the file COPYING for details.

"""
Permission backend to manage "own" objects
"""

from django.conf import settings
from django.contrib.auth.models import User
from django.core.exceptions import ObjectDoesNotExist
from django.db.models.loading import cache

import models

class ObjectPermBackend(object):
    supports_object_permissions = True
    supports_anonymous_user = True

    def authenticate(self, username, password):
        # managed by the default backend
        return None

    def has_perm(self, user_obj, perm, model=None, obj=None):
        if not user_obj.is_authenticated():
            return False
        if not model:
            # let it manage by the default backend
            return False
        try:
            ishtar_user = models.IshtarUser.objects.get(user_ptr=user_obj)
        except ObjectDoesNotExist:
            return False
        try:
            is_ownperm = perm.split('.')[-1].split('_')[1] == 'own'
        except IndexError:
            is_ownperm = False
        if ishtar_user.has_right('administrator'):
            return True
        main_right = ishtar_user.person.has_right(perm) \
                           or user_obj.has_perm(perm)
        if not main_right or not is_ownperm:
            return main_right
        if obj is None:
            model_name = perm.split('_')[-1].capitalize()
            model = None
            for app in cache.get_apps():
                for modl in cache.get_models(app):
                    if modl.__name__ == model_name:
                        model = modl
            if not model:
                return False
            return not is_ownperm or model.has_item_of(ishtar_user)
        return not is_ownperm or obj.is_own(user_obj)