moviewyrm/bookwyrm/models/base_model.py
2020-12-31 12:22:00 -08:00

283 lines
9.9 KiB
Python

''' base model with default fields '''
from base64 import b64encode
from functools import reduce
import operator
from uuid import uuid4
from Crypto.PublicKey import RSA
from Crypto.Signature import pkcs1_15
from Crypto.Hash import SHA256
from django.core.paginator import Paginator
from django.db import models
from django.db.models import Q
from django.dispatch import receiver
from bookwyrm import activitypub
from bookwyrm.settings import DOMAIN, PAGE_LENGTH
from .fields import ImageField, ManyToManyField, RemoteIdField
class BookWyrmModel(models.Model):
''' shared fields '''
created_date = models.DateTimeField(auto_now_add=True)
updated_date = models.DateTimeField(auto_now=True)
remote_id = RemoteIdField(null=True, activitypub_field='id')
def get_remote_id(self):
''' generate a url that resolves to the local object '''
base_path = 'https://%s' % DOMAIN
if hasattr(self, 'user'):
base_path = self.user.remote_id
model_name = type(self).__name__.lower()
return '%s/%s/%d' % (base_path, model_name, self.id)
class Meta:
''' this is just here to provide default fields for other models '''
abstract = True
@property
def local_path(self):
''' how to link to this object in the local app '''
return self.get_remote_id().replace('https://%s' % DOMAIN, '')
@receiver(models.signals.post_save)
#pylint: disable=unused-argument
def execute_after_save(sender, instance, created, *args, **kwargs):
''' set the remote_id after save (when the id is available) '''
if not created or not hasattr(instance, 'get_remote_id'):
return
if not instance.remote_id:
instance.remote_id = instance.get_remote_id()
instance.save()
def unfurl_related_field(related_field):
''' load reverse lookups (like public key owner or Status attachment '''
if hasattr(related_field, 'all'):
return [unfurl_related_field(i) for i in related_field.all()]
if related_field.reverse_unfurl:
return related_field.field_to_activity()
return related_field.remote_id
class ActivitypubMixin:
''' add this mixin for models that are AP serializable '''
activity_serializer = lambda: {}
reverse_unfurl = False
def __init__(self, *args, **kwargs):
''' collect some info on model fields '''
self.image_fields = []
self.many_to_many_fields = []
self.simple_fields = [] # "simple"
for field in self._meta.get_fields():
if not hasattr(field, 'field_to_activity'):
continue
if isinstance(field, ImageField):
self.image_fields.append(field)
elif isinstance(field, ManyToManyField):
self.many_to_many_fields.append(field)
else:
self.simple_fields.append(field)
self.activity_fields = self.image_fields + \
self.many_to_many_fields + self.simple_fields
self.deserialize_reverse_fields = self.deserialize_reverse_fields \
if hasattr(self, 'deserialize_reverse_fields') else []
self.serialize_reverse_fields = self.serialize_reverse_fields \
if hasattr(self, 'serialize_reverse_fields') else []
super().__init__(*args, **kwargs)
@classmethod
def find_existing_by_remote_id(cls, remote_id):
''' look up a remote id in the db '''
return cls.find_existing({'id': remote_id})
@classmethod
def find_existing(cls, data):
''' compare data to fields that can be used for deduplation.
This always includes remote_id, but can also be unique identifiers
like an isbn for an edition '''
filters = []
for field in cls._meta.get_fields():
if not hasattr(field, 'deduplication_field') or \
not field.deduplication_field:
continue
value = data.get(field.get_activitypub_field())
if not value:
continue
filters.append({field.name: value})
if hasattr(cls, 'origin_id') and 'id' in data:
# kinda janky, but this handles special case for books
filters.append({'origin_id': data['id']})
if not filters:
# if there are no deduplication fields, it will match the first
# item no matter what. this shouldn't happen but just in case.
return None
objects = cls.objects
if hasattr(objects, 'select_subclasses'):
objects = objects.select_subclasses()
# an OR operation on all the match fields
match = objects.filter(
reduce(
operator.or_, (Q(**f) for f in filters)
)
)
# there OUGHT to be only one match
return match.first()
def to_activity(self):
''' convert from a model to an activity '''
activity = {}
for field in self.activity_fields:
field.set_activity_from_field(activity, self)
if hasattr(self, 'serialize_reverse_fields'):
# for example, editions of a work
for model_field_name, activity_field_name in \
self.serialize_reverse_fields:
related_field = getattr(self, model_field_name)
activity[activity_field_name] = \
unfurl_related_field(related_field)
if not activity.get('id'):
activity['id'] = self.get_remote_id()
return self.activity_serializer(**activity).serialize()
def to_create_activity(self, user, **kwargs):
''' returns the object wrapped in a Create activity '''
activity_object = self.to_activity(**kwargs)
signer = pkcs1_15.new(RSA.import_key(user.key_pair.private_key))
content = activity_object['content']
signed_message = signer.sign(SHA256.new(content.encode('utf8')))
create_id = self.remote_id + '/activity'
signature = activitypub.Signature(
creator='%s#main-key' % user.remote_id,
created=activity_object['published'],
signatureValue=b64encode(signed_message).decode('utf8')
)
return activitypub.Create(
id=create_id,
actor=user.remote_id,
to=activity_object['to'],
cc=activity_object['cc'],
object=activity_object,
signature=signature,
).serialize()
def to_delete_activity(self, user):
''' notice of deletion '''
return activitypub.Delete(
id=self.remote_id + '/activity',
actor=user.remote_id,
to=['%s/followers' % user.remote_id],
cc=['https://www.w3.org/ns/activitystreams#Public'],
object=self.to_activity(),
).serialize()
def to_update_activity(self, user):
''' wrapper for Updates to an activity '''
activity_id = '%s#update/%s' % (self.remote_id, uuid4())
return activitypub.Update(
id=activity_id,
actor=user.remote_id,
to=['https://www.w3.org/ns/activitystreams#Public'],
object=self.to_activity()
).serialize()
def to_undo_activity(self, user):
''' undo an action '''
return activitypub.Undo(
id='%s#undo' % self.remote_id,
actor=user.remote_id,
object=self.to_activity()
).serialize()
class OrderedCollectionPageMixin(ActivitypubMixin):
''' just the paginator utilities, so you don't HAVE to
override ActivitypubMixin's to_activity (ie, for outbox '''
@property
def collection_remote_id(self):
''' this can be overriden if there's a special remote id, ie outbox '''
return self.remote_id
def to_ordered_collection(self, queryset, \
remote_id=None, page=False, **kwargs):
''' an ordered collection of whatevers '''
remote_id = remote_id or self.remote_id
if page:
return to_ordered_collection_page(
queryset, remote_id, **kwargs)
name = self.name if hasattr(self, 'name') else None
owner = self.user.remote_id if hasattr(self, 'user') else ''
paginated = Paginator(queryset, PAGE_LENGTH)
return activitypub.OrderedCollection(
id=remote_id,
totalItems=paginated.count,
name=name,
owner=owner,
first='%s?page=1' % remote_id,
last='%s?page=%d' % (remote_id, paginated.num_pages)
).serialize()
# pylint: disable=unused-argument
def to_ordered_collection_page(
queryset, remote_id, id_only=False, page=1, **kwargs):
''' serialize and pagiante a queryset '''
paginated = Paginator(queryset, PAGE_LENGTH)
activity_page = paginated.page(page)
if id_only:
items = [s.remote_id for s in activity_page.object_list]
else:
items = [s.to_activity() for s in activity_page.object_list]
prev_page = next_page = None
if activity_page.has_next():
next_page = '%s?page=%d' % (remote_id, activity_page.next_page_number())
if activity_page.has_previous():
prev_page = '%s?page=%d' % \
(remote_id, activity_page.previous_page_number())
return activitypub.OrderedCollectionPage(
id='%s?page=%s' % (remote_id, page),
partOf=remote_id,
orderedItems=items,
next=next_page,
prev=prev_page
).serialize()
class OrderedCollectionMixin(OrderedCollectionPageMixin):
''' extends activitypub models to work as ordered collections '''
@property
def collection_queryset(self):
''' usually an ordered collection model aggregates a different model '''
raise NotImplementedError('Model must define collection_queryset')
activity_serializer = activitypub.OrderedCollection
def to_activity(self, **kwargs):
''' an ordered collection of the specified model queryset '''
return self.to_ordered_collection(self.collection_queryset, **kwargs)