Send Undo(Announce) activity when repost is deleted

src/activitypub/activity.rs

@@ -285,19 +285,39 @@ pub fn create_activity_announce(
     instance_url: &str,
     actor_profile: &DbActorProfile,
     post: &Post,
+    repost_id: &Uuid,
 ) -> Activity {
     let object_id = post.get_object_id(instance_url);
     let activity = create_activity(
         instance_url,
         &actor_profile.username,
         ANNOUNCE,
-        None,
+        Some(repost_id),
         object_id,
         vec![AP_PUBLIC.to_string()],
     );
     activity
 }
 
+pub fn create_activity_undo_announce(
+    instance_url: &str,
+    actor_profile: &DbActorProfile,
+    repost_id: &Uuid,
+) -> Activity {
+    let object_id = get_object_url(
+        instance_url,
+        repost_id,
+    );
+    create_activity(
+        instance_url,
+        &actor_profile.username,
+        UNDO,
+        None,
+        object_id,
+        vec![AP_PUBLIC.to_string()],
+    )
+}
+
 pub fn create_activity_delete_note(
     instance_url: &str,
     actor_profile: &DbActorProfile,

src/activitypub/receiver.rs

@@ -438,15 +438,27 @@ pub async fn receive_activity(
             unfollow(db_client, &source_profile.id, &target_profile.id).await?;
         },
         (UNDO, _) => {
-            // Undo(Like)
             let object_id = get_object_id(activity.object)?;
-            let reaction = get_reaction_by_activity_id(db_client, &object_id).await?;
+            match get_reaction_by_activity_id(db_client, &object_id).await {
+                Ok(reaction) => {
+                    // Undo(Like)
                     delete_reaction(
                         db_client,
                         &reaction.author_id,
                         &reaction.post_id,
                     ).await?;
                 },
+                Err(DatabaseError::NotFound(_)) => {
+                    // Undo(Announce)
+                    let post = get_post_by_object_id(db_client, &object_id).await?;
+                    match post.repost_of_id {
+                        Some(_) => delete_post(db_client, &post.id).await?,
+                        None => return Err(HttpError::NotFoundError("object")),
+                    };
+                },
+                Err(other_error) => return Err(other_error.into()),
+            };
+        },
         (UPDATE, PERSON) => {
             let actor: Actor = serde_json::from_value(activity.object)
                 .map_err(|_| ValidationError("invalid actor data"))?;

src/mastodon_api/statuses/views.rs

@@ -9,6 +9,7 @@ use crate::activitypub::activity::{
     create_activity_like,
     create_activity_undo_like,
     create_activity_announce,
+    create_activity_undo_announce,
     create_activity_delete_note,
 };
 use crate::activitypub::actor::Actor;
@@ -323,7 +324,7 @@ async fn reblog(
         repost_of_id: Some(status_id),
         ..Default::default()
     };
-    create_post(db_client, &current_user.id, repost_data).await?;
+    let repost = create_post(db_client, &current_user.id, repost_data).await?;
     let mut post = get_post_by_id(db_client, &status_id).await?;
     get_reposted_posts(db_client, vec![&mut post]).await?;
     get_actions_for_posts(db_client, &current_user.id, vec![&mut post]).await?;
@@ -333,6 +334,7 @@ async fn reblog(
         &config.instance_url(),
         &current_user.profile,
         &post,
+        &repost.id,
     );
     let mut recipients: Vec<Actor> = Vec::new();
     let followers = get_followers(db_client, &current_user.id).await?;
@@ -370,6 +372,29 @@ async fn unreblog(
     let mut post = get_post_by_id(db_client, &status_id).await?;
     get_reposted_posts(db_client, vec![&mut post]).await?;
     get_actions_for_posts(db_client, &current_user.id, vec![&mut post]).await?;
+
+    // Federate
+    let activity = create_activity_undo_announce(
+        &config.instance_url(),
+        &current_user.profile,
+        &repost_id,
+    );
+    let mut recipients: Vec<Actor> = Vec::new();
+    let followers = get_followers(db_client, &current_user.id).await?;
+    for follower in followers {
+        let maybe_remote_follower = follower.remote_actor()
+            .map_err(|_| HttpError::InternalError)?;
+        if let Some(remote_actor) = maybe_remote_follower {
+            recipients.push(remote_actor);
+        };
+    };
+    let maybe_remote_author = post.author.remote_actor()
+        .map_err(|_| HttpError::InternalError)?;
+    if let Some(remote_actor) = maybe_remote_author {
+        recipients.push(remote_actor);
+    };
+    deliver_activity(&config, &current_user, activity, recipients);
+
     let status = Status::from_post(post, &config.instance_url());
     Ok(HttpResponse::Ok().json(status))
 }