crates/apub/src/fetcher/community.rs

   1 use crate::{
   2   fetcher::{
   3     fetch::fetch_remote_object,
   4     get_or_fetch_and_upsert_user,
   5     is_deleted,
   6     should_refetch_actor,
   7   },
   8   inbox::user_inbox::receive_announce,
   9   objects::FromApub,
  10   GroupExt,
  11 };
  12 use activitystreams::{
  13   actor::ApActorExt,
  14   collection::{CollectionExt, OrderedCollection},
  15   object::ObjectExt,
  16 };
  17 use anyhow::Context;
  18 use diesel::result::Error::NotFound;
  19 use lemmy_db_queries::{source::community::Community_, ApubObject, Joinable};
  20 use lemmy_db_schema::source::community::{Community, CommunityModerator, CommunityModeratorForm};
  21 use lemmy_structs::blocking;
  22 use lemmy_utils::{location_info, LemmyError};
  23 use lemmy_websocket::LemmyContext;
  24 use log::debug;
  25 use url::Url;
  26
  27 /// Get a community from its apub ID.
  28 ///
  29 /// If it exists locally and `!should_refetch_actor()`, it is returned directly from the database.
  30 /// Otherwise it is fetched from the remote instance, stored and returned.
  31 pub(crate) async fn get_or_fetch_and_upsert_community(
  32   apub_id: &Url,
  33   context: &LemmyContext,
  34   recursion_counter: &mut i32,
  35 ) -> Result<Community, LemmyError> {
  36   let apub_id_owned = apub_id.to_owned();
  37   let community = blocking(context.pool(), move |conn| {
  38     Community::read_from_apub_id(conn, &apub_id_owned.into())
  39   })
  40   .await?;
  41
  42   match community {
  43     Ok(c) if !c.local && should_refetch_actor(c.last_refreshed_at) => {
  44       debug!("Fetching and updating from remote community: {}", apub_id);
  45       fetch_remote_community(apub_id, context, Some(c), recursion_counter).await
  46     }
  47     Ok(c) => Ok(c),
  48     Err(NotFound {}) => {
  49       debug!("Fetching and creating remote community: {}", apub_id);
  50       fetch_remote_community(apub_id, context, None, recursion_counter).await
  51     }
  52     Err(e) => Err(e.into()),
  53   }
  54 }
  55
  56 /// Request a community by apub ID from a remote instance, including moderators. If `old_community`,
  57 /// is set, this is an update for a community which is already known locally. If not, we don't know
  58 /// the community yet and also pull the outbox, to get some initial posts.
  59 async fn fetch_remote_community(
  60   apub_id: &Url,
  61   context: &LemmyContext,
  62   old_community: Option<Community>,
  63   recursion_counter: &mut i32,
  64 ) -> Result<Community, LemmyError> {
  65   let group = fetch_remote_object::<GroupExt>(context.client(), apub_id, recursion_counter).await;
  66
  67   if let Some(c) = old_community.to_owned() {
  68     if is_deleted(&group) {
  69       blocking(context.pool(), move |conn| {
  70         Community::update_deleted(conn, c.id, true)
  71       })
  72       .await??;
  73     } else if group.is_err() {
  74       // If fetching failed, return the existing data.
  75       return Ok(c);
  76     }
  77   }
  78
  79   let group = group?;
  80   let community =
  81     Community::from_apub(&group, context, apub_id.to_owned(), recursion_counter).await?;
  82
  83   // Also add the community moderators too
  84   let attributed_to = group.inner.attributed_to().context(location_info!())?;
  85   let creator_and_moderator_uris: Vec<&Url> = attributed_to
  86     .as_many()
  87     .context(location_info!())?
  88     .iter()
  89     .map(|a| a.as_xsd_any_uri().context(""))
  90     .collect::<Result<Vec<&Url>, anyhow::Error>>()?;
  91
  92   let mut creator_and_moderators = Vec::new();
  93
  94   for uri in creator_and_moderator_uris {
  95     let c_or_m = get_or_fetch_and_upsert_user(uri, context, recursion_counter).await?;
  96
  97     creator_and_moderators.push(c_or_m);
  98   }
  99
 100   // TODO: need to make this work to update mods of existing communities
 101   if old_community.is_none() {
 102     let community_id = community.id;
 103     blocking(context.pool(), move |conn| {
 104       for mod_ in creator_and_moderators {
 105         let community_moderator_form = CommunityModeratorForm {
 106           community_id,
 107           user_id: mod_.id,
 108         };
 109
 110         CommunityModerator::join(conn, &community_moderator_form)?;
 111       }
 112       Ok(()) as Result<(), LemmyError>
 113     })
 114     .await??;
 115   }
 116
 117   // only fetch outbox for new communities, otherwise this can create an infinite loop
 118   if old_community.is_none() {
 119     let outbox = group.inner.outbox()?.context(location_info!())?;
 120     fetch_community_outbox(context, outbox, &community, recursion_counter).await?
 121   }
 122
 123   Ok(community)
 124 }
 125
 126 async fn fetch_community_outbox(
 127   context: &LemmyContext,
 128   outbox: &Url,
 129   community: &Community,
 130   recursion_counter: &mut i32,
 131 ) -> Result<(), LemmyError> {
 132   let outbox =
 133     fetch_remote_object::<OrderedCollection>(context.client(), outbox, recursion_counter).await?;
 134   let outbox_activities = outbox.items().context(location_info!())?.clone();
 135   let mut outbox_activities = outbox_activities.many().context(location_info!())?;
 136   if outbox_activities.len() > 20 {
 137     outbox_activities = outbox_activities[0..20].to_vec();
 138   }
 139
 140   for activity in outbox_activities {
 141     receive_announce(context, activity, community, recursion_counter).await?;
 142   }
 143
 144   Ok(())
 145 }