Synnefo

# Copyright 2011-2012 GRNET S.A. All rights reserved.

#

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# without modification, are permitted provided that the following

# conditions are met:

#

#   1. Redistributions of source code must retain the above

#      copyright notice, this list of conditions and the following

#      disclaimer.

#

#   2. Redistributions in binary form must reproduce the above

#      copyright notice, this list of conditions and the following

#      disclaimer in the documentation and/or other materials

#      provided with the distribution.

#

# THIS SOFTWARE IS PROVIDED BY GRNET S.A. ``AS IS'' AND ANY EXPRESS

# OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED

# WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR

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# CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,

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# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN

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# The views and conclusions contained in the software and

# documentation are those of the authors and should not be

# interpreted as representing official policies, either expressed

# or implied, of GRNET S.A.

import hashlib

import uuid

import logging

from time import asctime

from datetime import datetime, timedelta

from base64 import b64encode

from random import randint

from collections import defaultdict

from django.db import models, IntegrityError

from django.contrib.auth.models import User, UserManager, Group, Permission

from django.utils.translation import ugettext as _

from django.db import transaction

from django.core.exceptions import ValidationError

from django.db import transaction

from django.db.models.signals import (pre_save, post_save, post_syncdb,

                                      post_delete)

from django.contrib.contenttypes.models import ContentType

from django.dispatch import Signal

from django.db.models import Q

from astakos.im.settings import (DEFAULT_USER_LEVEL, INVITATIONS_PER_LEVEL,

                                 AUTH_TOKEN_DURATION, BILLING_FIELDS,

                                 EMAILCHANGE_ACTIVATION_DAYS, LOGGING_LEVEL)

from astakos.im.endpoints.qh import (register_users, send_quota,

                                              register_resources)

from astakos.im.endpoints.aquarium.producer import report_user_event

from astakos.im.functions import send_invitation

from astakos.im.tasks import propagate_groupmembers_quota

from astakos.im.functions import send_invitation

import astakos.im.messages as astakos_messages

logger = logging.getLogger(__name__)

DEFAULT_CONTENT_TYPE = None

try:

    content_type = ContentType.objects.get(app_label='im', model='astakosuser')

except:

    content_type = DEFAULT_CONTENT_TYPE

RESOURCE_SEPARATOR = '.'

inf = float('inf')

class Service(models.Model):

    name = models.CharField('Name', max_length=255, unique=True, db_index=True)

    url = models.FilePathField()

    icon = models.FilePathField(blank=True)

    auth_token = models.CharField('Authentication Token', max_length=32,

                                  null=True, blank=True)

    auth_token_created = models.DateTimeField('Token creation date', null=True)

    auth_token_expires = models.DateTimeField(

        'Token expiration date', null=True)

    def save(self, **kwargs):

        if not self.id:

            self.renew_token()

        super(Service, self).save(**kwargs)

    def renew_token(self):

        md5 = hashlib.md5()

        md5.update(self.name.encode('ascii', 'ignore'))

        md5.update(self.url.encode('ascii', 'ignore'))

        md5.update(asctime())

        self.auth_token = b64encode(md5.digest())

        self.auth_token_created = datetime.now()

        self.auth_token_expires = self.auth_token_created + \

            timedelta(hours=AUTH_TOKEN_DURATION)

    def __str__(self):

        return self.name

    @property

    def resources(self):

        return self.resource_set.all()

    @resources.setter

    def resources(self, resources):

        for s in resources:

            self.resource_set.create(**s)

    def add_resource(self, service, resource, uplimit, update=True):

        """Raises ObjectDoesNotExist, IntegrityError"""

        resource = Resource.objects.get(service__name=service, name=resource)

        if update:

            AstakosUserQuota.objects.update_or_create(user=self,

                                                      resource=resource,

                                                      defaults={'uplimit': uplimit})

        else:

            q = self.astakosuserquota_set

            q.create(resource=resource, uplimit=uplimit)

class ResourceMetadata(models.Model):

    key = models.CharField('Name', max_length=255, unique=True, db_index=True)

    value = models.CharField('Value', max_length=255)

class Resource(models.Model):

    name = models.CharField('Name', max_length=255, unique=True, db_index=True)

    meta = models.ManyToManyField(ResourceMetadata)

    service = models.ForeignKey(Service)

    desc = models.TextField('Description', null=True)

    unit = models.CharField('Name', null=True, max_length=255)

    group = models.CharField('Group', null=True, max_length=255)

    def __str__(self):

        return '%s%s%s' % (self.service, RESOURCE_SEPARATOR, self.name)

class GroupKind(models.Model):

    name = models.CharField('Name', max_length=255, unique=True, db_index=True)

    def __str__(self):

        return self.name

class AstakosGroup(Group):

    kind = models.ForeignKey(GroupKind)

    homepage = models.URLField(

        'Homepage Url', max_length=255, null=True, blank=True)

    desc = models.TextField('Description', null=True)

    policy = models.ManyToManyField(

        Resource,

        null=True,

        blank=True,

        through='AstakosGroupQuota'

    )

    creation_date = models.DateTimeField(

        'Creation date',

        default=datetime.now()

    )

    issue_date = models.DateTimeField('Issue date', null=True)

    expiration_date = models.DateTimeField(

        'Expiration date',

         null=True

    )

    moderation_enabled = models.BooleanField(

        'Moderated membership?',

        default=True

    )

    approval_date = models.DateTimeField(

        'Activation date',

        null=True,

        blank=True

    )

    estimated_participants = models.PositiveIntegerField(

        'Estimated #members',

        null=True,

        blank=True,

    )

    max_participants = models.PositiveIntegerField(

        'Maximum numder of participants',

        null=True,

        blank=True

    )

    @property

    def is_disabled(self):

        if not self.approval_date:

            return True

        return False

    @property

    def is_enabled(self):

        if self.is_disabled:

            return False

        if not self.issue_date:

            return False

        if not self.expiration_date:

            return True

        now = datetime.now()

        if self.issue_date > now:

            return False

        if now >= self.expiration_date:

            return False

        return True

    def enable(self):

        if self.is_enabled:

            return

        self.approval_date = datetime.now()

        self.save()

        quota_disturbed.send(sender=self, users=self.approved_members)

        propagate_groupmembers_quota.apply_async(

            args=[self], eta=self.issue_date)

        propagate_groupmembers_quota.apply_async(

            args=[self], eta=self.expiration_date)

    def disable(self):

        if self.is_disabled:

            return

        self.approval_date = None

        self.save()

        quota_disturbed.send(sender=self, users=self.approved_members)

    @transaction.commit_manually

    def approve_member(self, person):

        m, created = self.membership_set.get_or_create(person=person)

        # update date_joined in any case

        try:

            m.approve()

        except:

            transaction.rollback()

            raise

        else:

            transaction.commit()

#     def disapprove_member(self, person):

#         self.membership_set.remove(person=person)

    @property

    def members(self):

        q = self.membership_set.select_related().all()

        return [m.person for m in q]

    @property

    def approved_members(self):

        q = self.membership_set.select_related().all()

        return [m.person for m in q if m.is_approved]

    @property

    def quota(self):

        d = defaultdict(int)

        for q in self.astakosgroupquota_set.select_related().all():

            d[q.resource] += q.uplimit or inf

        return d

    def add_policy(self, service, resource, uplimit, update=True):

        """Raises ObjectDoesNotExist, IntegrityError"""

        print '#', locals()

        resource = Resource.objects.get(service__name=service, name=resource)

        if update:

            AstakosGroupQuota.objects.update_or_create(

                group=self,

                resource=resource,

                defaults={'uplimit': uplimit}

            )

        else:

            q = self.astakosgroupquota_set

            q.create(resource=resource, uplimit=uplimit)

    @property

    def policies(self):

        return self.astakosgroupquota_set.select_related().all()

    @policies.setter

    def policies(self, policies):

        for p in policies:

            service = p.get('service', None)

            resource = p.get('resource', None)

            uplimit = p.get('uplimit', 0)

            update = p.get('update', True)

            self.add_policy(service, resource, uplimit, update)

    @property

    def owners(self):

        return self.owner.all()

    @property

    def owner_details(self):

        return self.owner.select_related().all()

    @owners.setter

    def owners(self, l):

        self.owner = l

        map(self.approve_member, l)

class AstakosUser(User):

    """

    Extends ``django.contrib.auth.models.User`` by defining additional fields.

    """

    # Use UserManager to get the create_user method, etc.

    objects = UserManager()

    affiliation = models.CharField('Affiliation', max_length=255, blank=True)

    provider = models.CharField('Provider', max_length=255, blank=True)

    #for invitations

    user_level = DEFAULT_USER_LEVEL

    level = models.IntegerField('Inviter level', default=user_level)

    invitations = models.IntegerField(

        'Invitations left', default=INVITATIONS_PER_LEVEL.get(user_level, 0))

    auth_token = models.CharField('Authentication Token', max_length=32,

                                  null=True, blank=True)

    auth_token_created = models.DateTimeField('Token creation date', null=True)

    auth_token_expires = models.DateTimeField(

        'Token expiration date', null=True)

    updated = models.DateTimeField('Update date')

    is_verified = models.BooleanField('Is verified?', default=False)

    # ex. screen_name for twitter, eppn for shibboleth

    third_party_identifier = models.CharField(

        'Third-party identifier', max_length=255, null=True, blank=True)

    email_verified = models.BooleanField('Email verified?', default=False)

    has_credits = models.BooleanField('Has credits?', default=False)

    has_signed_terms = models.BooleanField(

        'I agree with the terms', default=False)

    date_signed_terms = models.DateTimeField(

        'Signed terms date', null=True, blank=True)

    activation_sent = models.DateTimeField(

        'Activation sent data', null=True, blank=True)

    policy = models.ManyToManyField(

        Resource, null=True, through='AstakosUserQuota')

    astakos_groups = models.ManyToManyField(

        AstakosGroup, verbose_name=_('agroups'), blank=True,

        help_text=_(astakos_messages.ASTAKOSUSER_GROUPS_HELP),

        through='Membership')

    __has_signed_terms = False

    disturbed_quota = models.BooleanField('Needs quotaholder syncing',

                                           default=False, db_index=True)

    owner = models.ManyToManyField(

        AstakosGroup, related_name='owner', null=True)

    class Meta:

        unique_together = ("provider", "third_party_identifier")

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

        super(AstakosUser, self).__init__(*args, **kwargs)

        self.__has_signed_terms = self.has_signed_terms

        if not self.id:

            self.is_active = False

    @property

    def realname(self):

        return '%s %s' % (self.first_name, self.last_name)

    @realname.setter

    def realname(self, value):

        parts = value.split(' ')

        if len(parts) == 2:

            self.first_name = parts[0]

            self.last_name = parts[1]

        else:

            self.last_name = parts[0]

    def add_permission(self, pname):

        if self.has_perm(pname):

            return

        p, created = Permission.objects.get_or_create(codename=pname,

                                                      name=pname.capitalize(),

                                                      content_type=content_type)

        self.user_permissions.add(p)

    def remove_permission(self, pname):

        if self.has_perm(pname):

            return

        p = Permission.objects.get(codename=pname,

                                   content_type=content_type)

        self.user_permissions.remove(p)

    @property

    def invitation(self):

        try:

            return Invitation.objects.get(username=self.email)

        except Invitation.DoesNotExist:

            return None

    def invite(self, email, realname):

        inv = Invitation(inviter=self, username=email, realname=realname)

        inv.save()

        send_invitation(inv)

        self.invitations = max(0, self.invitations - 1)

        self.save()

    @property

    def quota(self):

        """Returns a dict with the sum of quota limits per resource"""

        d = defaultdict(int)

        for q in self.policies:

            d[q.resource] += q.uplimit or inf

        for m in self.extended_groups:

            if not m.is_approved:

                continue

            g = m.group

            if not g.is_enabled:

                continue

            for r, uplimit in g.quota.iteritems():

                d[r] += uplimit or inf

        # TODO set default for remaining

        return d

    @property

    def policies(self):

        return self.astakosuserquota_set.select_related().all()

    @policies.setter

    def policies(self, policies):

        for p in policies:

            service = policies.get('service', None)

            resource = policies.get('resource', None)

            uplimit = policies.get('uplimit', 0)

            update = policies.get('update', True)

            self.add_policy(service, resource, uplimit, update)

    def add_policy(self, service, resource, uplimit, update=True):

        """Raises ObjectDoesNotExist, IntegrityError"""

        resource = Resource.objects.get(service__name=service, name=resource)

        if update:

            AstakosUserQuota.objects.update_or_create(user=self,

                                                      resource=resource,

                                                      defaults={'uplimit': uplimit})

        else:

            q = self.astakosuserquota_set

            q.create(resource=resource, uplimit=uplimit)

    def remove_policy(self, service, resource):

        """Raises ObjectDoesNotExist, IntegrityError"""

        resource = Resource.objects.get(service__name=service, name=resource)

        q = self.policies.get(resource=resource).delete()

    @property

    def extended_groups(self):

        return self.membership_set.select_related().all()

    @extended_groups.setter

    def extended_groups(self, groups):

        #TODO exceptions

        for name in (groups or ()):

            group = AstakosGroup.objects.get(name=name)

            self.membership_set.create(group=group)

    def save(self, update_timestamps=True, **kwargs):

        if update_timestamps:

            if not self.id:

                self.date_joined = datetime.now()

            self.updated = datetime.now()

        # update date_signed_terms if necessary

        if self.__has_signed_terms != self.has_signed_terms:

            self.date_signed_terms = datetime.now()

        if not self.id:

            # set username

            while not self.username:

                username = uuid.uuid4().hex[:30]

                try:

                    AstakosUser.objects.get(username=username)

                except AstakosUser.DoesNotExist:

                    self.username = username

            if not self.provider:

                self.provider = 'local'

            self.email = self.email.lower()

        self.validate_unique_email_isactive()

        if self.is_active and self.activation_sent:

            # reset the activation sent

            self.activation_sent = None

        super(AstakosUser, self).save(**kwargs)

    def renew_token(self):

        md5 = hashlib.md5()

        md5.update(self.username)

        md5.update(self.realname.encode('ascii', 'ignore'))

        md5.update(asctime())

        self.auth_token = b64encode(md5.digest())

        self.auth_token_created = datetime.now()

        self.auth_token_expires = self.auth_token_created + \

            timedelta(hours=AUTH_TOKEN_DURATION)

        msg = 'Token renewed for %s' % self.email

        logger.log(LOGGING_LEVEL, msg)

    def __unicode__(self):

        return '%s (%s)' % (self.realname, self.email)

    def conflicting_email(self):

        q = AstakosUser.objects.exclude(username=self.username)

        q = q.filter(email=self.email)

        if q.count() != 0:

            return True

        return False

    def validate_unique_email_isactive(self):

        """

        Implements a unique_together constraint for email and is_active fields.

        """

        q = AstakosUser.objects.exclude(username=self.username)

        q = q.filter(email=self.email)

        q = q.filter(is_active=self.is_active)

        if q.count() != 0:

            raise ValidationError({'__all__': [_(astakos_messages.UNIQUE_EMAIL_IS_ACTIVE_CONSTRAIN_ERR)]})

    @property

    def signed_terms(self):

        term = get_latest_terms()

        if not term:

            return True

        if not self.has_signed_terms:

            return False

        if not self.date_signed_terms:

            return False

        if self.date_signed_terms < term.date:

            self.has_signed_terms = False

            self.date_signed_terms = None

            self.save()

            return False

        return True

    def store_disturbed_quota(self, set=True):

        self.disturbed_qutoa = set

        self.save()

class Membership(models.Model):

    person = models.ForeignKey(AstakosUser)

    group = models.ForeignKey(AstakosGroup)

    date_requested = models.DateField(default=datetime.now(), blank=True)

    date_joined = models.DateField(null=True, db_index=True, blank=True)

    class Meta:

        unique_together = ("person", "group")

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

        if not self.id:

            if not self.group.moderation_enabled:

                self.date_joined = datetime.now()

        super(Membership, self).save(*args, **kwargs)

    @property

    def is_approved(self):

        if self.date_joined:

            return True

        return False

    def approve(self):

        if self.group.max_participants:

            assert len(self.group.approved_members) + 1 <= self.group.max_participants

        self.date_joined = datetime.now()

        self.save()

        quota_disturbed.send(sender=self, users=(self.person,))

    def disapprove(self):

        self.delete()

        quota_disturbed.send(sender=self, users=(self.person,))

class AstakosQuotaManager(models.Manager):

    def _update_or_create(self, **kwargs):

        assert kwargs, \

            'update_or_create() must be passed at least one keyword argument'

        obj, created = self.get_or_create(**kwargs)

        defaults = kwargs.pop('defaults', {})

        if created:

            return obj, True, False

        else:

            try:

                params = dict(

                    [(k, v) for k, v in kwargs.items() if '__' not in k])

                params.update(defaults)

                for attr, val in params.items():

                    if hasattr(obj, attr):

                        setattr(obj, attr, val)

                sid = transaction.savepoint()

                obj.save(force_update=True)

                transaction.savepoint_commit(sid)

                return obj, False, True

            except IntegrityError, e:

                transaction.savepoint_rollback(sid)

                try:

                    return self.get(**kwargs), False, False

                except self.model.DoesNotExist:

                    raise e

    update_or_create = _update_or_create

class AstakosGroupQuota(models.Model):

    objects = AstakosQuotaManager()

    limit = models.PositiveIntegerField('Limit', null=True)    # obsolete field

    uplimit = models.BigIntegerField('Up limit', null=True)

    resource = models.ForeignKey(Resource)

    group = models.ForeignKey(AstakosGroup, blank=True)

    class Meta:

        unique_together = ("resource", "group")

class AstakosUserQuota(models.Model):

    objects = AstakosQuotaManager()

    limit = models.PositiveIntegerField('Limit', null=True)    # obsolete field

    uplimit = models.BigIntegerField('Up limit', null=True)

    resource = models.ForeignKey(Resource)

    user = models.ForeignKey(AstakosUser)

    class Meta:

        unique_together = ("resource", "user")

class ApprovalTerms(models.Model):

    """

    Model for approval terms

    """

    date = models.DateTimeField(

        'Issue date', db_index=True, default=datetime.now())

    location = models.CharField('Terms location', max_length=255)

class Invitation(models.Model):

    """

    Model for registring invitations

    """

    inviter = models.ForeignKey(AstakosUser, related_name='invitations_sent',

                                null=True)

    realname = models.CharField('Real name', max_length=255)

    username = models.CharField('Unique ID', max_length=255, unique=True)

    code = models.BigIntegerField('Invitation code', db_index=True)

    is_consumed = models.BooleanField('Consumed?', default=False)

    created = models.DateTimeField('Creation date', auto_now_add=True)

    consumed = models.DateTimeField('Consumption date', null=True, blank=True)

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

        super(Invitation, self).__init__(*args, **kwargs)

        if not self.id:

            self.code = _generate_invitation_code()

    def consume(self):

        self.is_consumed = True

        self.consumed = datetime.now()

        self.save()

    def __unicode__(self):

        return '%s -> %s [%d]' % (self.inviter, self.username, self.code)

class EmailChangeManager(models.Manager):

    @transaction.commit_on_success

    def change_email(self, activation_key):

        """

        Validate an activation key and change the corresponding

        ``User`` if valid.

        If the key is valid and has not expired, return the ``User``

        after activating.

        If the key is not valid or has expired, return ``None``.

        If the key is valid but the ``User`` is already active,

        return ``None``.

        After successful email change the activation record is deleted.

        Throws ValueError if there is already

        """

        try:

            email_change = self.model.objects.get(

                activation_key=activation_key)

            if email_change.activation_key_expired():

                email_change.delete()

                raise EmailChange.DoesNotExist

            # is there an active user with this address?

            try:

                AstakosUser.objects.get(email=email_change.new_email_address)

            except AstakosUser.DoesNotExist:

                pass

            else:

                raise ValueError(_(astakos_messages.NEW_EMAIL_ADDR_RESERVED))

            # update user

            user = AstakosUser.objects.get(pk=email_change.user_id)

            user.email = email_change.new_email_address

            user.save()

            email_change.delete()

            return user

        except EmailChange.DoesNotExist:

            raise ValueError(_(astakos_messages.INVALID_ACTIVATION_KEY))

class EmailChange(models.Model):

    new_email_address = models.EmailField(_(u'new e-mail address'),

                                          help_text=_(astakos_messages.EMAIL_CHANGE_NEW_ADDR_HELP))

    user = models.ForeignKey(

        AstakosUser, unique=True, related_name='emailchange_user')

    requested_at = models.DateTimeField(default=datetime.now())

    activation_key = models.CharField(

        max_length=40, unique=True, db_index=True)

    objects = EmailChangeManager()

    def activation_key_expired(self):

        expiration_date = timedelta(days=EMAILCHANGE_ACTIVATION_DAYS)

        return self.requested_at + expiration_date < datetime.now()

class AdditionalMail(models.Model):

    """

    Model for registring invitations

    """

    owner = models.ForeignKey(AstakosUser)

    email = models.EmailField()

def _generate_invitation_code():

    while True:

        code = randint(1, 2L ** 63 - 1)

        try:

            Invitation.objects.get(code=code)

            # An invitation with this code already exists, try again

        except Invitation.DoesNotExist:

            return code

def get_latest_terms():

    try:

        term = ApprovalTerms.objects.order_by('-id')[0]

        return term

    except IndexError:

        pass

    return None

def create_astakos_user(u):

    try:

        AstakosUser.objects.get(user_ptr=u.pk)

    except AstakosUser.DoesNotExist:

        extended_user = AstakosUser(user_ptr_id=u.pk)

        extended_user.__dict__.update(u.__dict__)

        extended_user.renew_token()

        extended_user.save()

    except BaseException, e:

        logger.exception(e)

        pass

def fix_superusers(sender, **kwargs):

    # Associate superusers with AstakosUser

    admins = User.objects.filter(is_superuser=True)

    for u in admins:

        create_astakos_user(u)

def user_post_save(sender, instance, created, **kwargs):

    if not created:

        return

    create_astakos_user(instance)

def set_default_group(user):

    try:

        default = AstakosGroup.objects.get(name='default')

        Membership(

            group=default, person=user, date_joined=datetime.now()).save()

    except AstakosGroup.DoesNotExist, e:

        logger.exception(e)

def astakosuser_pre_save(sender, instance, **kwargs):

    instance.aquarium_report = False

    instance.new = False

    try:

        db_instance = AstakosUser.objects.get(id=instance.id)

    except AstakosUser.DoesNotExist:

        # create event

        instance.aquarium_report = True

        instance.new = True

    else:

        get = AstakosUser.__getattribute__

        l = filter(lambda f: get(db_instance, f) != get(instance, f),

                   BILLING_FIELDS)

        instance.aquarium_report = True if l else False

def astakosuser_post_save(sender, instance, created, **kwargs):

    if instance.aquarium_report:

        report_user_event(instance, create=instance.new)

    if not created:

        return

    set_default_group(instance)

    # TODO handle socket.error & IOError

    register_users((instance,))

#     instance.renew_token()

def resource_post_save(sender, instance, created, **kwargs):

    if not created:

        return

    register_resources((instance,))

def send_quota_disturbed(sender, instance, **kwargs):

    users = []

    extend = users.extend

    if sender == Membership:

        if not instance.group.is_enabled:

            return

        extend([instance.person])

    elif sender == AstakosUserQuota:

        extend([instance.user])

    elif sender == AstakosGroupQuota:

        if not instance.group.is_enabled:

            return

        extend(instance.group.astakosuser_set.all())

    elif sender == AstakosGroup:

        if not instance.is_enabled:

            return

    quota_disturbed.send(sender=sender, users=users)

def on_quota_disturbed(sender, users, **kwargs):

    print '>>>', locals()

    if not users:

        return

    send_quota(users)

post_syncdb.connect(fix_superusers)

post_save.connect(user_post_save, sender=User)

pre_save.connect(astakosuser_pre_save, sender=AstakosUser)

post_save.connect(astakosuser_post_save, sender=AstakosUser)

post_save.connect(resource_post_save, sender=Resource)

quota_disturbed = Signal(providing_args=["users"])

quota_disturbed.connect(on_quota_disturbed)

post_delete.connect(send_quota_disturbed, sender=AstakosGroup)

post_delete.connect(send_quota_disturbed, sender=Membership)

post_save.connect(send_quota_disturbed, sender=AstakosUserQuota)

post_delete.connect(send_quota_disturbed, sender=AstakosUserQuota)

post_save.connect(send_quota_disturbed, sender=AstakosGroupQuota)

post_delete.connect(send_quota_disturbed, sender=AstakosGroupQuota)