lemmy/crates/apub/src/fetcher/mod.rs

use activitypub_federation::{
  config::Data,
  fetch::webfinger::webfinger_resolve_actor,
  traits::{Actor, Object},
};
use diesel::NotFound;
use itertools::Itertools;
use lemmy_api_common::context::LemmyContext;
use lemmy_db_schema::traits::ApubActor;
use lemmy_db_views::structs::LocalUserView;
use lemmy_utils::error::LemmyError;

pub mod post_or_comment;
pub mod search;
pub mod user_or_community;

/// Resolve actor identifier like `!news@example.com` to user or community object.
///
/// In case the requesting user is logged in and the object was not found locally, it is attempted
/// to fetch via webfinger from the original instance.
#[tracing::instrument(skip_all)]
pub async fn resolve_actor_identifier<ActorType, DbActor>(
  identifier: &str,
  context: &Data<LemmyContext>,
  local_user_view: &Option<LocalUserView>,
  include_deleted: bool,
) -> Result<ActorType, LemmyError>
where
  ActorType: Object<DataType = LemmyContext, Error = LemmyError>
    + Object
    + Actor
    + From<DbActor>
    + Send
    + 'static,
  for<'de2> <ActorType as Object>::Kind: serde::Deserialize<'de2>,
  DbActor: ApubActor + Send + 'static,
{
  // remote actor
  if identifier.contains('@') {
    let (name, domain) = identifier
      .splitn(2, '@')
      .collect_tuple()
      .expect("invalid query");
    let actor = DbActor::read_from_name_and_domain(context.pool(), name, domain).await;
    if actor.is_ok() {
      Ok(actor?.into())
    } else if local_user_view.is_some() {
      // Fetch the actor from its home instance using webfinger
      let actor: ActorType = webfinger_resolve_actor(identifier, context).await?;
      Ok(actor)
    } else {
      Err(NotFound.into())
    }
  }
  // local actor
  else {
    let identifier = identifier.to_string();
    Ok(
      DbActor::read_from_name(context.pool(), &identifier, include_deleted)
        .await?
        .into(),
    )
  }
}