Send Undo/Dislike activity (fixes #4465) (#5825)

crates/api/api/src/comment/like.rs

@@ -91,7 +91,8 @@ pub async fn like_comment(
       object_id: orig_comment.comment.ap_id,
       actor: local_user_view.person.clone(),
       community: orig_comment.community,
-      score: data.score,
+      previous_score: orig_comment.comment_actions.and_then(|a| a.like_score),
+      new_score: data.score,
     },
     &context,
   )?;

crates/api/api/src/post/like.rs

@@ -41,9 +41,10 @@ pub async fn like_post(
   check_bot_account(&local_user_view.person)?;
 
   // Check for a community ban
-  let post = PostView::read(&mut context.pool(), post_id, None, local_instance_id, false).await?;
+  let orig_post =
+    PostView::read(&mut context.pool(), post_id, None, local_instance_id, false).await?;
 
-  check_community_user_action(&local_user_view, &post.community, &mut context.pool()).await?;
+  check_community_user_action(&local_user_view, &orig_post.community, &mut context.pool()).await?;
 
   let mut like_form = PostLikeForm::new(data.post_id, local_user_view.person.id, data.score);
 
@@ -67,13 +68,20 @@ pub async fn like_post(
 
   ActivityChannel::submit_activity(
     SendActivityData::LikePostOrComment {
-      object_id: post.post.ap_id,
+      object_id: orig_post.post.ap_id,
       actor: local_user_view.person.clone(),
-      community: post.community.clone(),
-      score: data.score,
+      community: orig_post.community.clone(),
+      previous_score: orig_post.post_actions.and_then(|a| a.like_score),
+      new_score: data.score,
     },
     &context,
   )?;
 
-  build_post_response(context.deref(), post.community.id, local_user_view, post_id).await
+  build_post_response(
+    context.deref(),
+    orig_post.community.id,
+    local_user_view,
+    post_id,
+  )
+  .await
 }

crates/api/api_utils/src/send_activity.rs

@@ -61,7 +61,8 @@ pub enum SendActivityData {
     object_id: DbUrl,
     actor: Person,
     community: Community,
-    score: i16,
+    previous_score: Option<i16>,
+    new_score: i16,
   },
   FollowCommunity(Community, Person, bool),
   FollowMultiCommunity(MultiCommunity, Person, bool),

crates/apub/src/activities/mod.rs

@@ -256,8 +256,19 @@ pub async fn match_outgoing_activities(
         object_id,
         actor,
         community,
-        score,
-      } => send_like_activity(object_id, actor, community, score, context).await,
+        previous_score,
+        new_score,
+      } => {
+        send_like_activity(
+          object_id,
+          actor,
+          community,
+          previous_score,
+          new_score,
+          context,
+        )
+        .await
+      }
       FollowCommunity(community, person, follow) => {
         send_follow(Either::Left(community.into()), person, follow, &context).await
       }

crates/apub/src/activities/voting/mod.rs

@@ -38,7 +38,8 @@ pub(crate) async fn send_like_activity(
   object_id: DbUrl,
   actor: Person,
   community: Community,
-  score: i16,
+  previous_score: Option<i16>,
+  new_score: i16,
   context: Data<LemmyContext>,
 ) -> LemmyResult<()> {
   let object_id: ObjectId<PostOrComment> = object_id.into();
@@ -47,13 +48,17 @@ pub(crate) async fn send_like_activity(
 
   let empty = ActivitySendTargets::empty();
   // score of 1 means upvote, -1 downvote, 0 undo a previous vote
-  if score != 0 {
-    let vote = Vote::new(object_id, &actor, score.try_into()?, &context)?;
+  if new_score != 0 {
+    let vote = Vote::new(object_id, &actor, new_score.try_into()?, &context)?;
     let activity = AnnouncableActivities::Vote(vote);
     send_activity_in_community(activity, &actor, &community, empty, false, &context).await
   } else {
-    // Lemmy API doesn't distinguish between Undo/Like and Undo/Dislike, so we hardcode it here.
-    let vote = Vote::new(object_id, &actor, VoteType::Like, &context)?;
+    let previous_vote_type = if previous_score.unwrap_or_default() > 0 {
+      VoteType::Like
+    } else {
+      VoteType::Dislike
+    };
+    let vote = Vote::new(object_id, &actor, previous_vote_type, &context)?;
     let undo_vote = UndoVote::new(vote, &actor, &context)?;
     let activity = AnnouncableActivities::UndoVote(undo_vote);
     send_activity_in_community(activity, &actor, &community, empty, false, &context).await