takahe/activities/services/post.py

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2022-12-20 01:59:06 -08:00
from typing import cast
from activities.models import Post, PostInteraction, PostInteractionStates, PostStates
from users.models import Identity
class PostService:
"""
High-level operations on Posts
"""
def __init__(self, post: Post):
self.post = post
def interact_as(self, identity: Identity, type: str):
"""
Performs an interaction on this Post
"""
interaction = PostInteraction.objects.get_or_create(
type=type,
identity=identity,
post=self.post,
)[0]
if interaction.state in [
PostInteractionStates.undone,
PostInteractionStates.undone_fanned_out,
]:
interaction.transition_perform(PostInteractionStates.new)
def uninteract_as(self, identity, type):
"""
Undoes an interaction on this Post
"""
for interaction in PostInteraction.objects.filter(
type=type,
identity=identity,
post=self.post,
):
interaction.transition_perform(PostInteractionStates.undone)
def like_as(self, identity: Identity):
self.interact_as(identity, PostInteraction.Types.like)
def unlike_as(self, identity: Identity):
self.uninteract_as(identity, PostInteraction.Types.like)
def boost_as(self, identity: Identity):
self.interact_as(identity, PostInteraction.Types.boost)
def unboost_as(self, identity: Identity):
self.uninteract_as(identity, PostInteraction.Types.boost)
def context(self, identity: Identity | None) -> tuple[list[Post], list[Post]]:
"""
Returns ancestor/descendant information.
Ancestors are guaranteed to be in order from closest to furthest.
Descendants are in depth-first order, starting with closest.
If identity is provided, includes mentions/followers-only posts they
can see. Otherwise, shows unlisted and above only.
"""
num_ancestors = 10
num_descendants = 50
# Retrieve ancestors via parent walk
ancestors: list[Post] = []
ancestor = self.post
while ancestor.in_reply_to and len(ancestors) < num_ancestors:
ancestor = cast(Post, ancestor.in_reply_to_post())
if ancestor.state in [PostStates.deleted, PostStates.deleted_fanned_out]:
break
ancestors.append(ancestor)
# Retrieve descendants via breadth-first-search
descendants: list[Post] = []
queue = [self.post]
while queue and len(descendants) < num_descendants:
node = queue.pop()
child_queryset = (
Post.objects.not_hidden()
.filter(in_reply_to=node.object_uri)
.select_related("author", "author__domain")
.prefetch_related("emojis")
.order_by("published")
)
if identity:
child_queryset = child_queryset.visible_to(
identity=identity, include_replies=True
)
else:
child_queryset = child_queryset.unlisted(include_replies=True)
for child in child_queryset:
descendants.append(child)
queue.append(child)
return ancestors, descendants