from django.conf import settings

from django.contrib.contenttypes.models import ContentType

from django.contrib.auth.models import Group

from guardian.core import ObjectPermissionChecker

from guardian.shortcuts import assign, remove_perm

try:

    from threading import local

except ImportError:

    from django.utils._threading_local import local

_thread_locals = local()

def get_current_user():

    return getattr(_thread_locals, 'user', None)

def protect_models():

    user = get_current_user()

    for cls in ToProtect.get_models():

            protect_model(cls, user)

def unprotect_models():

    for cls in ToProtect.get_models():

            unprotect_model(cls)

class ToProtect(object):

    @staticmethod

    def get_models():

        if hasattr(ToProtect, 'cls_list'):

            return ToProtect.cls_list

        cls_list = []

        for cls_name in settings.USE_GROUP_PERMISSIONS:

            cls_type = ContentType.objects.get(model=cls_name.lower())

            cls_list.append(cls_type.model_class())

        ToProtect.cls_list = cls_list

        return cls_list

def protect_model(cls, user):   

    cls.safe_objects.user = user

    cls.old_save = cls.save

    cls.old_delete = cls.delete

    class_name = cls.__name__.lower()

    cls.save = change_security(user, class_name)(cls.save)

    cls.delete = change_security(user, class_name)(cls.delete)    

def unprotect_model(cls): 

    if hasattr(cls, 'old_save'):

        cls.save = cls.old_save 

        cls.delete = cls.old_delete 

        del cls.old_save    

        del cls.old_delete

        cls.safe_objects.user = None 

def change_security(user, cls_name):

    def wrapper(func):

        def wrapped(self, *args, **kwargs):                      

            if self.pk and not user.has_perm('change_%s' % cls_name, self):

                raise AttributeError('User %s is not allowed to change object %s' % (user, self))

            return func(self, *args, **kwargs)

        return wrapped    

    return wrapper

def set_forbidden_stream(xml, user):

    cls = ContentType.objects.get(model='content')

    cls = cls.model_class()

    old_user = cls.safe_objects.user

    obj_list = cls.safe_objects.all()

    for elem in xml.xpath('/iri/medias/media'):

        if not obj_list.filter(iri_id=elem.get('id')):

            elem.set('video', settings.FORBIDDEN_STREAM_URL)

    cls.safe_objects.user = old_user 

    return xml

def add_change_attr(user, obj_list):

    if len(obj_list) == 0:

        return []

    model_name = obj_list[0].__class__.__name__.lower()

    ctype = ContentType.objects.get(model=model_name)

    cls = ctype.model_class()

    checker = ObjectPermissionChecker(user)

    perm_name = "%s.change_%s" % (cls._meta.app_label, model_name)

    for obj in obj_list:

        if checker.has_perm(perm_name, obj):

            obj.change = True

        else:

            obj.change = False

    return obj_list

def assign_object_to_groups(object, permissions):

    name = object.__class__.__name__.lower()

    for elem in permissions:

        group = Group.objects.get(id=elem['group'])

        if elem['share']:

            assign('view_%s' % name, group, object)

            if elem['perms'] == 'write':

                assign('change_%s' % name, group, object)

        else:

            remove_perm('view_%s' % name, group, object)