takahe/activities/models/fan_out.py

from asgiref.sync import sync_to_async
from django.db import models

from activities.models.timeline_event import TimelineEvent
from core.ld import canonicalise
from core.signatures import HttpSignature
from stator.models import State, StateField, StateGraph, StatorModel


class FanOutStates(StateGraph):
    new = State(try_interval=300)
    sent = State()

    new.transitions_to(sent)

    @classmethod
    async def handle_new(cls, instance: "FanOut"):
        """
        Sends the fan-out to the right inbox.
        """
        fan_out = await instance.afetch_full()
        if fan_out.identity.local:
            # Make a timeline event directly
            await sync_to_async(TimelineEvent.add_post)(
                identity=fan_out.identity,
                post=fan_out.subject_post,
            )
        else:
            # Send it to the remote inbox
            post = await fan_out.subject_post.afetch_full()
            # Sign it and send it
            await HttpSignature.signed_request(
                uri=fan_out.identity.inbox_uri,
                body=canonicalise(post.to_create_ap()),
                private_key=post.author.public_key,
                key_id=post.author.public_key_id,
            )
        return cls.sent


class FanOut(StatorModel):
    """
    An activity that needs to get to an inbox somewhere.
    """

    class Types(models.TextChoices):
        post = "post"
        boost = "boost"

    state = StateField(FanOutStates)

    # The user this event is targeted at
    identity = models.ForeignKey(
        "users.Identity",
        on_delete=models.CASCADE,
        related_name="fan_outs",
    )

    # What type of activity it is
    type = models.CharField(max_length=100, choices=Types.choices)

    # Links to the appropriate objects
    subject_post = models.ForeignKey(
        "activities.Post",
        on_delete=models.CASCADE,
        blank=True,
        null=True,
        related_name="fan_outs",
    )

    created = models.DateTimeField(auto_now_add=True)
    updated = models.DateTimeField(auto_now=True)

    ### Async helpers ###

    async def afetch_full(self):
        """
        Returns a version of the object with all relations pre-loaded
        """
        return await FanOut.objects.select_related("identity", "subject_post").aget(
            pk=self.pk
        )