Synnefo » astakos

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

#

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# without modification, are permitted provided that the following

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#

#   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

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# 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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# The views and conclusions contained in the software and

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# 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 urlparse import urlparse

from urllib import quote

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.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 django.core.urlresolvers import reverse

from django.utils.http import int_to_base36

from django.contrib.auth.tokens import default_token_generator

from django.conf import settings

from django.utils.importlib import import_module

from django.core.validators import email_re

from astakos.im.settings import (

    DEFAULT_USER_LEVEL, INVITATIONS_PER_LEVEL,

    AUTH_TOKEN_DURATION, BILLING_FIELDS,

    EMAILCHANGE_ACTIVATION_DAYS, LOGGING_LEVEL,

    GROUP_CREATION_SUBJECT

)

from astakos.im.endpoints.qh import (

    register_users, send_quota, register_resources

)

from astakos.im import auth_providers

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.notifications import build_notification

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 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('Start 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)

    def approve_member(self, person):

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

        m.approve()

    @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"""

        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 AstakosUserManager(UserManager):

    def get_auth_provider_user(self, provider, **kwargs):

        """

        Retrieve AstakosUser instance associated with the specified third party

        id.

        """

        kwargs = dict(map(lambda x: ('auth_providers__%s' % x[0], x[1]),

                          kwargs.iteritems()))

        return self.get(auth_providers__module=provider, **kwargs)

class AstakosUser(User):

    """

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

    """

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

                                   null=True)

    # DEPRECATED FIELDS: provider, third_party_identifier moved in

    #                    AstakosUserProvider model.

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

                                null=True)

    # ex. screen_name for twitter, eppn for shibboleth

    third_party_identifier = models.CharField(_('Third-party identifier'),

                                              max_length=255, null=True,

                                              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)

    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)

    objects = AstakosUserManager()

    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

            self.username = self.email

        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, flush_sessions=False, current_key=None):

        md5 = hashlib.md5()

        md5.update(settings.SECRET_KEY)

        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)

        if flush_sessions:

            self.flush_sessions(current_key)

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

        logger.log(LOGGING_LEVEL, msg)

    def flush_sessions(self, current_key=None):

        q = self.sessions

        if current_key:

            q = q.exclude(session_key=current_key)

        keys = q.values_list('session_key', flat=True)

        if keys:

            msg = 'Flushing sessions: %s' % ','.join(keys)

            logger.log(LOGGING_LEVEL, msg, [])

        engine = import_module(settings.SESSION_ENGINE)

        for k in keys:

            s = engine.SessionStore(k)

            s.flush()

    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__iexact=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.all()

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

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

        if self.id:

            q = q.filter(~Q(id = self.id))

        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 set_invitations_level(self):

        """

        Update user invitation level

        """

        level = self.invitation.inviter.level + 1

        self.level = level

        self.invitations = INVITATIONS_PER_LEVEL.get(level, 0)

    def can_login_with_auth_provider(self, provider):

        if not self.has_auth_provider(provider):

            return False

        else:

            return auth_providers.get_provider(provider).is_available_for_login()

    def can_add_auth_provider(self, provider, **kwargs):

        provider_settings = auth_providers.get_provider(provider)

        if not provider_settings.is_available_for_login():

            return False

        if self.has_auth_provider(provider) and \

           provider_settings.one_per_user:

            return False

        if 'identifier' in kwargs:

            try:

                # provider with specified params already exist

                existing_user = AstakosUser.objects.get_auth_provider_user(provider,

                                                                   **kwargs)

            except AstakosUser.DoesNotExist:

                return True

            else:

                return False

        return True

    def can_remove_auth_provider(self, provider):

        if len(self.get_active_auth_providers()) <= 1:

            return False

        return True

    def can_change_password(self):

        return self.has_auth_provider('local', auth_backend='astakos')

    def has_auth_provider(self, provider, **kwargs):

        return bool(self.auth_providers.filter(module=provider,

                                               **kwargs).count())

    def add_auth_provider(self, provider, **kwargs):

        if self.can_add_auth_provider(provider, **kwargs):

            self.auth_providers.create(module=provider, active=True, **kwargs)

        else:

            raise Exception('Cannot add provider')

    def add_pending_auth_provider(self, pending):

        """

        Convert PendingThirdPartyUser object to AstakosUserAuthProvider entry for

        the current user.

        """

        if not isinstance(pending, PendingThirdPartyUser):

            pending = PendingThirdPartyUser.objects.get(token=pending)

        provider = self.add_auth_provider(pending.provider,

                               identifier=pending.third_party_identifier)

        if email_re.match(pending.email or '') and pending.email != self.email:

            self.additionalmail_set.get_or_create(email=pending.email)

        pending.delete()

        return provider

    def remove_auth_provider(self, provider, **kwargs):

        self.auth_providers.get(module=provider, **kwargs).delete()

    # user urls

    def get_resend_activation_url(self):

        return reverse('send_activation', {'user_id': self.pk})

    def get_activation_url(self, nxt=False):

        url = "%s?auth=%s" % (reverse('astakos.im.views.activate'),

                                 quote(self.auth_token))

        if nxt:

            url += "&next=%s" % quote(nxt)

        return url

    def get_password_reset_url(self, token_generator=default_token_generator):

        return reverse('django.contrib.auth.views.password_reset_confirm',

                          kwargs={'uidb36':int_to_base36(self.id),

                                  'token':token_generator.make_token(self)})

    def get_auth_providers(self):

        return self.auth_providers.all()

    def get_available_auth_providers(self):

        """

        Returns a list of providers available for user to connect to.

        """

        providers = []

        for module, provider_settings in auth_providers.PROVIDERS.iteritems():

            if self.can_add_auth_provider(module):

                providers.append(provider_settings(self))

        return providers

    def get_active_auth_providers(self):

        providers = []

        for provider in self.auth_providers.active():

            if auth_providers.get_provider(provider.module).is_available_for_login():

                providers.append(provider)

        return providers

    @property

    def auth_providers_display(self):

        return ",".join(map(lambda x:unicode(x), self.auth_providers.active()))

class AstakosUserAuthProviderManager(models.Manager):

    def active(self):

        return self.filter(active=True)

class AstakosUserAuthProvider(models.Model):

    """

    Available user authentication methods.

    """

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

                                   null=True, default=None)

    user = models.ForeignKey(AstakosUser, related_name='auth_providers')

    module = models.CharField(_('Provider'), max_length=255, blank=False,

                                default='local')

    identifier = models.CharField(_('Third-party identifier'),

                                              max_length=255, null=True,

                                              blank=True)

    active = models.BooleanField(default=True)

    auth_backend = models.CharField(_('Backend'), max_length=255, blank=False,

                                   default='astakos')

    objects = AstakosUserAuthProviderManager()

    class Meta:

        unique_together = (('identifier', 'module', 'user'), )

    @property

    def settings(self):

        return auth_providers.get_provider(self.module)

    @property

    def details_display(self):

        return self.settings.details_tpl % self.__dict__

    def can_remove(self):

        return self.user.can_remove_auth_provider(self.module)

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

        ret = super(AstakosUserAuthProvider, self).delete(*args, **kwargs)

        if self.module == 'local':

            self.user.set_unusable_password()

            self.user.save()

        return ret

    def __repr__(self):

        return '<AstakosUserAuthProvider %s:%s>' % (self.module, self.identifier)

    def __unicode__(self):

        if self.identifier:

            return "%s:%s" % (self.module, self.identifier)

        if self.auth_backend:

            return "%s:%s" % (self.module, self.auth_backend)

        return self.module

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.is_approved:

            return

        if self.group.max_participants:

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

            'Maximum participant number has been reached.'

        self.date_joined = datetime.now()

        self.save()

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

    def disapprove(self):

        approved = self.is_approved()

        self.delete()

        if approved:

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

class ExtendedManager(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 = ExtendedManager()

    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 = ExtendedManager()

    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__iexact=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

class PendingThirdPartyUser(models.Model):

    """

    Model for registring successful third party user authentications

    """

    third_party_identifier = models.CharField(_('Third-party identifier'), max_length=255, null=True, blank=True)

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

    email = models.EmailField(_('e-mail address'), blank=True, null=True)

    first_name = models.CharField(_('first name'), max_length=30, blank=True)

    last_name = models.CharField(_('last name'), max_length=30, blank=True)

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

    username = models.CharField(_('username'), max_length=30, unique=True, help_text=_("Required. 30 characters or fewer. Letters, numbers and @/./+/-/_ characters"))

    token = models.CharField(_('Token'), max_length=255, null=True, blank=True)

    created = models.DateTimeField(auto_now_add=True, null=True, blank=True)

    class Meta:

        unique_together = ("provider", "third_party_identifier")

    @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 save(self, **kwargs):

        if not self.id:

            # set username

            while not self.username:

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

                try:

                    AstakosUser.objects.get(username = username)

                except AstakosUser.DoesNotExist, e:

                    self.username = username

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

    def generate_token(self):

        self.password = self.third_party_identifier

        self.last_login = datetime.now()

        self.token = default_token_generator.make_token(self)

class SessionCatalog(models.Model):

    session_key = models.CharField(_('session key'), max_length=40)

    user = models.ForeignKey(AstakosUser, related_name='sessions', null=True)

class MemberAcceptPolicy(models.Model):

    policy = models.CharField(_('Policy'), max_length=255, unique=True, db_index=True)

    description = models.CharField(_('Description'), max_length=80)

    def __str__(self):

        return self.policy

try:

    auto_accept = MemberAcceptPolicy.objects.get(policy='auto_accept')

except:

    auto_accept = None

class ProjectDefinition(models.Model):

    name = models.CharField(max_length=80)

    homepage = models.URLField(max_length=255, null=True, blank=True)

    description = models.TextField(null=True)

    start_date = models.DateTimeField()

    end_date = models.DateTimeField()

    member_accept_policy = models.ForeignKey(MemberAcceptPolicy)

    limit_on_members_number = models.PositiveIntegerField(null=True,blank=True)

    resource_grants = models.ManyToManyField(

        Resource,

        null=True,

        blank=True,

        through='ProjectResourceGrant'

    )

    def save(self):

        self.validate_name()

        super(ProjectDefinition, self).save()

    def validate_name(self):

        """

        Validate name uniqueness among all active projects.

        """

        alive_projects = list(get_alive_projects())

        q = filter(lambda p: p.definition.name==self.name, alive_projects)

        if q:

            raise ValidationError({'name': [_(astakos_messages.UNIQUE_PROJECT_NAME_CONSTRAIN_ERR)]})

    @property

    def violated_resource_grants(self):

        return False

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

        """Raises ObjectDoesNotExist, IntegrityError"""

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

        if update:

            ProjectResourceGrant.objects.update_or_create(

                project_definition=self,

                resource=resource,

                defaults={'member_limit': uplimit}

            )

        else:

            q = self.projectresourcegrant_set

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

    @property

    def resource_policies(self):

        return self.projectresourcegrant_set.all()

    @resource_policies.setter

    def resource_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_resource_policy(service, resource, uplimit, update)

    def get_absolute_url(self):

        return reverse('project_application_detail', args=(self.serial,))

class ProjectResourceGrant(models.Model):

    objects = ExtendedManager()

    member_limit = models.BigIntegerField(null=True)

    project_limit = models.BigIntegerField(null=True)

    resource = models.ForeignKey(Resource)

    project_definition = models.ForeignKey(ProjectDefinition, blank=True)

    class Meta:

        unique_together = ("resource", "project_definition")

class ProjectApplication(models.Model):

    serial = models.CharField(

        primary_key=True,

        max_length=30,

        unique=True,

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

    )

    applicant = models.ForeignKey(AstakosUser, related_name='my_project_applications')

    owner = models.ForeignKey(AstakosUser, related_name='own_project_applications')

    comments = models.TextField(null=True, blank=True)

    definition = models.OneToOneField(ProjectDefinition)

    issue_date = models.DateTimeField()

    precursor_application = models.OneToOneField('ProjectApplication',

        null=True,

        blank=True

    )

class Project(models.Model):

    serial = models.CharField(

        _('username'),

        primary_key=True,

        max_length=30,

        unique=True,

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

    )

    application = models.OneToOneField(ProjectApplication, related_name='project')

    creation_date = models.DateTimeField()

    last_approval_date = models.DateTimeField()

    termination_date = models.DateTimeField()

    members = models.ManyToManyField(AstakosUser, through='ProjectMembership')

    last_synced_application = models.OneToOneField(

        ProjectApplication, related_name='last_project', null=True, blank=True

    )

    @property

    def definition(self):

        return self.application.definition

    @property

    def is_valid(self):

        try:

            self.application.definition.validate_name()

        except ValidationError:

            return False

        else:

            return True