260 lines
8.4 KiB
Python
260 lines
8.4 KiB
Python
from typing import Optional
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from django.db import models
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from core.ld import canonicalise
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from core.signatures import HttpSignature
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from stator.models import State, StateField, StateGraph, StatorModel
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from users.models.identity import Identity
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class FollowStates(StateGraph):
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unrequested = State(try_interval=300)
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local_requested = State(try_interval=24 * 60 * 60)
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remote_requested = State(try_interval=24 * 60 * 60)
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accepted = State(externally_progressed=True)
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undone_locally = State(try_interval=60 * 60)
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undone_remotely = State()
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unrequested.transitions_to(local_requested)
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unrequested.transitions_to(remote_requested)
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local_requested.transitions_to(accepted)
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remote_requested.transitions_to(accepted)
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accepted.transitions_to(undone_locally)
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undone_locally.transitions_to(undone_remotely)
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@classmethod
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async def handle_unrequested(cls, instance: "Follow"):
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"""
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Follows that are unrequested need us to deliver the Follow object
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to the target server.
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"""
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follow = await instance.afetch_full()
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# Remote follows should not be here
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if not follow.source.local:
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return cls.remote_requested
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# Sign it and send it
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await HttpSignature.signed_request(
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uri=follow.target.inbox_uri,
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body=canonicalise(follow.to_ap()),
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private_key=follow.source.public_key,
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key_id=follow.source.public_key_id,
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)
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return cls.local_requested
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@classmethod
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async def handle_local_requested(cls, instance: "Follow"):
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# TODO: Resend follow requests occasionally
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pass
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@classmethod
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async def handle_remote_requested(cls, instance: "Follow"):
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"""
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Items in remote_requested need us to send an Accept object to the
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source server.
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"""
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follow = await instance.afetch_full()
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await HttpSignature.signed_request(
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uri=follow.source.inbox_uri,
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body=canonicalise(follow.to_accept_ap()),
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private_key=follow.target.public_key,
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key_id=follow.target.public_key_id,
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)
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return cls.accepted
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@classmethod
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async def handle_undone_locally(cls, instance: "Follow"):
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"""
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Delivers the Undo object to the target server
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"""
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follow = await instance.afetch_full()
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await HttpSignature.signed_request(
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uri=follow.target.inbox_uri,
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body=canonicalise(follow.to_undo_ap()),
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private_key=follow.source.public_key,
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key_id=follow.source.public_key_id,
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)
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return cls.undone_remotely
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class Follow(StatorModel):
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"""
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When one user (the source) follows other (the target)
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"""
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source = models.ForeignKey(
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"users.Identity",
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on_delete=models.CASCADE,
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related_name="outbound_follows",
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)
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target = models.ForeignKey(
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"users.Identity",
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on_delete=models.CASCADE,
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related_name="inbound_follows",
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)
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uri = models.CharField(blank=True, null=True, max_length=500)
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note = models.TextField(blank=True, null=True)
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state = StateField(FollowStates)
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created = models.DateTimeField(auto_now_add=True)
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updated = models.DateTimeField(auto_now=True)
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class Meta:
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unique_together = [("source", "target")]
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def __str__(self):
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return f"#{self.id}: {self.source} → {self.target}"
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### Alternate fetchers/constructors ###
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@classmethod
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def maybe_get(cls, source, target) -> Optional["Follow"]:
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"""
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Returns a follow if it exists between source and target
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"""
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try:
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return Follow.objects.get(source=source, target=target)
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except Follow.DoesNotExist:
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return None
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@classmethod
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def create_local(cls, source, target):
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"""
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Creates a Follow from a local Identity to the target
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(which can be local or remote).
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"""
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if not source.local:
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raise ValueError("You cannot initiate follows from a remote Identity")
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try:
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follow = Follow.objects.get(source=source, target=target)
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except Follow.DoesNotExist:
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follow = Follow.objects.create(source=source, target=target, uri="")
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follow.uri = source.actor_uri + f"follow/{follow.pk}/"
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# TODO: Local follow approvals
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if target.local:
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follow.state = FollowStates.accepted
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follow.save()
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return follow
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### Async helpers ###
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async def afetch_full(self):
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"""
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Returns a version of the object with all relations pre-loaded
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"""
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return await Follow.objects.select_related(
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"source", "source__domain", "target"
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).aget(pk=self.pk)
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### ActivityPub (outbound) ###
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def to_ap(self):
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"""
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Returns the AP JSON for this object
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"""
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return {
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"type": "Follow",
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"id": self.uri,
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"actor": self.source.actor_uri,
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"object": self.target.actor_uri,
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}
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def to_accept_ap(self):
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"""
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Returns the AP JSON for this objects' accept.
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"""
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return {
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"type": "Accept",
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"id": self.uri + "#accept",
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"actor": self.target.actor_uri,
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"object": self.to_ap(),
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}
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def to_undo_ap(self):
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"""
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Returns the AP JSON for this objects' undo.
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"""
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return {
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"type": "Undo",
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"id": self.uri + "#undo",
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"actor": self.source.actor_uri,
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"object": self.to_ap(),
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}
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### ActivityPub (inbound) ###
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@classmethod
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def by_ap(cls, data, create=False) -> "Follow":
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"""
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Retrieves a Follow instance by its ActivityPub JSON object.
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Optionally creates one if it's not present.
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Raises KeyError if it's not found and create is False.
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"""
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# Resolve source and target and see if a Follow exists
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source = Identity.by_actor_uri(data["actor"], create=create)
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target = Identity.by_actor_uri(data["object"])
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follow = cls.maybe_get(source=source, target=target)
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# If it doesn't exist, create one in the remote_requested state
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if follow is None:
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if create:
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return cls.objects.create(
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source=source,
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target=target,
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uri=data["id"],
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state=FollowStates.remote_requested,
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)
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else:
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raise KeyError(
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f"No follow with source {source} and target {target}", data
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)
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else:
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return follow
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@classmethod
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def handle_request_ap(cls, data):
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"""
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Handles an incoming follow request
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"""
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follow = cls.by_ap(data, create=True)
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# Force it into remote_requested so we send an accept
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follow.transition_perform(FollowStates.remote_requested)
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@classmethod
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def handle_accept_ap(cls, data):
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"""
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Handles an incoming Follow Accept for one of our follows
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"""
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# Ensure the Accept actor is the Follow's object
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if data["actor"] != data["object"]["object"]:
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raise ValueError("Accept actor does not match its Follow object", data)
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# Resolve source and target and see if a Follow exists (it really should)
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try:
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follow = cls.by_ap(data["object"])
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except KeyError:
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raise ValueError("No Follow locally for incoming Accept", data)
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# If the follow was waiting to be accepted, transition it
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if follow and follow.state in [
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FollowStates.unrequested,
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FollowStates.local_requested,
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]:
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follow.transition_perform(FollowStates.accepted)
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@classmethod
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def handle_undo_ap(cls, data):
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"""
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Handles an incoming Follow Undo for one of our follows
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"""
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# Ensure the Undo actor is the Follow's actor
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if data["actor"] != data["object"]["actor"]:
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raise ValueError("Undo actor does not match its Follow object", data)
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# Resolve source and target and see if a Follow exists (it hopefully does)
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try:
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follow = cls.by_ap(data["object"])
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except KeyError:
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raise ValueError("No Follow locally for incoming Undo", data)
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# Delete the follow
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follow.delete()
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