lemmy/crates/apub/src/http/community.rs

use crate::{
  activities::{
    community::announce::{AnnouncableActivities, AnnounceActivity},
    extract_community,
    following::{follow::FollowCommunity, undo::UndoFollowCommunity},
  },
  context::lemmy_context,
  generate_moderators_url,
  generate_outbox_url,
  http::{
    create_apub_response,
    create_apub_tombstone_response,
    payload_to_string,
    receive_activity,
  },
  objects::ToApub,
};
use activitystreams::{
  base::{AnyBase, BaseExt},
  collection::{CollectionExt, OrderedCollection, UnorderedCollection},
  url::Url,
};
use actix_web::{body::Body, web, web::Payload, HttpRequest, HttpResponse};
use lemmy_api_common::blocking;
use lemmy_apub_lib::traits::{ActivityFields, ActivityHandler};
use lemmy_db_queries::source::{activity::Activity_, community::Community_};
use lemmy_db_schema::source::{activity::Activity, community::Community};
use lemmy_db_views_actor::{
  community_follower_view::CommunityFollowerView,
  community_moderator_view::CommunityModeratorView,
};
use lemmy_utils::LemmyError;
use lemmy_websocket::LemmyContext;
use log::trace;
use serde::{Deserialize, Serialize};

#[derive(Deserialize)]
pub(crate) struct CommunityQuery {
  community_name: String,
}

/// Return the ActivityPub json representation of a local community over HTTP.
pub(crate) async fn get_apub_community_http(
  info: web::Path<CommunityQuery>,
  context: web::Data<LemmyContext>,
) -> Result<HttpResponse<Body>, LemmyError> {
  let community = blocking(context.pool(), move |conn| {
    Community::read_from_name(conn, &info.community_name)
  })
  .await??;

  if !community.deleted {
    let apub = community.to_apub(context.pool()).await?;

    Ok(create_apub_response(&apub))
  } else {
    Ok(create_apub_tombstone_response(&community.to_tombstone()?))
  }
}

#[derive(Clone, Debug, Deserialize, Serialize, ActivityHandler, ActivityFields)]
#[serde(untagged)]
#[activity_handler(LemmyContext)]
pub enum GroupInboxActivities {
  FollowCommunity(FollowCommunity),
  UndoFollowCommunity(UndoFollowCommunity),
  AnnouncableActivities(AnnouncableActivities),
}

/// Handler for all incoming receive to community inboxes.
pub async fn community_inbox(
  request: HttpRequest,
  payload: Payload,
  _path: web::Path<String>,
  context: web::Data<LemmyContext>,
) -> Result<HttpResponse, LemmyError> {
  let unparsed = payload_to_string(payload).await?;
  trace!("Received community inbox activity {}", unparsed);
  let activity = serde_json::from_str::<GroupInboxActivities>(&unparsed)?;

  receive_group_inbox(activity.clone(), request, &context).await?;

  if let GroupInboxActivities::AnnouncableActivities(announcable) = activity {
    let community = extract_community(&announcable.cc(), &context, &mut 0).await?;
    if community.local {
      AnnounceActivity::send(announcable, &community, vec![], &context).await?;
    }
  }
  Ok(HttpResponse::Ok().finish())
}

pub(in crate::http) async fn receive_group_inbox(
  activity: GroupInboxActivities,
  request: HttpRequest,
  context: &LemmyContext,
) -> Result<HttpResponse, LemmyError> {
  receive_activity(request, activity.clone(), context).await
}

/// Returns an empty followers collection, only populating the size (for privacy).
pub(crate) async fn get_apub_community_followers(
  info: web::Path<CommunityQuery>,
  context: web::Data<LemmyContext>,
) -> Result<HttpResponse<Body>, LemmyError> {
  let community = blocking(context.pool(), move |conn| {
    Community::read_from_name(conn, &info.community_name)
  })
  .await??;

  let community_id = community.id;
  let community_followers = blocking(context.pool(), move |conn| {
    CommunityFollowerView::for_community(conn, community_id)
  })
  .await??;

  let mut collection = UnorderedCollection::new();
  collection
    .set_many_contexts(lemmy_context())
    .set_id(community.followers_url.into())
    .set_total_items(community_followers.len() as u64);
  Ok(create_apub_response(&collection))
}

/// Returns the community outbox, which is populated by a maximum of 20 posts (but no other
/// activites like votes or comments).
pub(crate) async fn get_apub_community_outbox(
  info: web::Path<CommunityQuery>,
  context: web::Data<LemmyContext>,
) -> Result<HttpResponse<Body>, LemmyError> {
  let community = blocking(context.pool(), move |conn| {
    Community::read_from_name(conn, &info.community_name)
  })
  .await??;

  let community_actor_id = community.actor_id.to_owned();
  let activities = blocking(context.pool(), move |conn| {
    Activity::read_community_outbox(conn, &community_actor_id)
  })
  .await??;

  let activities = activities
    .iter()
    .map(AnyBase::from_arbitrary_json)
    .collect::<Result<Vec<AnyBase>, serde_json::Error>>()?;
  let len = activities.len();
  let mut collection = OrderedCollection::new();
  collection
    .set_many_items(activities)
    .set_many_contexts(lemmy_context())
    .set_id(generate_outbox_url(&community.actor_id)?.into())
    .set_total_items(len as u64);
  Ok(create_apub_response(&collection))
}

pub(crate) async fn get_apub_community_inbox(
  info: web::Path<CommunityQuery>,
  context: web::Data<LemmyContext>,
) -> Result<HttpResponse<Body>, LemmyError> {
  let community = blocking(context.pool(), move |conn| {
    Community::read_from_name(conn, &info.community_name)
  })
  .await??;

  let mut collection = OrderedCollection::new();
  collection
    .set_id(community.inbox_url.into())
    .set_many_contexts(lemmy_context());
  Ok(create_apub_response(&collection))
}

pub(crate) async fn get_apub_community_moderators(
  info: web::Path<CommunityQuery>,
  context: web::Data<LemmyContext>,
) -> Result<HttpResponse<Body>, LemmyError> {
  let community = blocking(context.pool(), move |conn| {
    Community::read_from_name(conn, &info.community_name)
  })
  .await??;

  // The attributed to, is an ordered vector with the creator actor_ids first,
  // then the rest of the moderators
  // TODO Technically the instance admins can mod the community, but lets
  // ignore that for now
  let cid = community.id;
  let moderators = blocking(context.pool(), move |conn| {
    CommunityModeratorView::for_community(conn, cid)
  })
  .await??;

  let moderators: Vec<Url> = moderators
    .into_iter()
    .map(|m| m.moderator.actor_id.into())
    .collect();
  let mut collection = OrderedCollection::new();
  collection
    .set_id(generate_moderators_url(&community.actor_id)?.into())
    .set_total_items(moderators.len() as u64)
    .set_many_items(moderators)
    .set_many_contexts(lemmy_context());
  Ok(create_apub_response(&collection))
}