DEV: Add post_action_users_list modifier for PostActionUsersController (#25740)

This commit adds another plugin modifier related to post
actions, similar to ae24e04a5e.

This will be used to exclude users who liked _and_ reacted to
the post, since now in discourse-reactions we make a Like when
a user reacts too. This will affect the display of the post footer.

app/controllers/post_action_users_controller.rb

@@ -12,19 +12,9 @@ class PostActionUsersController < ApplicationController
     page_size = fetch_limit_from_params(default: INDEX_LIMIT, max: INDEX_LIMIT)
 
     # Find the post, and then determine if they can see the post (if deleted)
-    post = Post.with_deleted.where(id: params[:id].to_i).first
+    post = Post.with_deleted.find_by(id: params[:id].to_i)
     guardian.ensure_can_see!(post)
 
-    unknown_user_ids = Set.new
-    if current_user.present?
-      result = DB.query_single(<<~SQL, user_id: current_user.id)
-        SELECT mu.muted_user_id AS id FROM muted_users AS mu WHERE mu.user_id = :user_id
-        UNION
-        SELECT iu.ignored_user_id AS id FROM ignored_users AS iu WHERE iu.user_id = :user_id
-      SQL
-      unknown_user_ids.merge(result)
-    end
-
     post_actions =
       post
         .post_actions
@@ -34,20 +24,23 @@ class PostActionUsersController < ApplicationController
         .order("post_actions.created_at ASC")
         .limit(page_size)
 
+    post_actions =
+      DiscoursePluginRegistry.apply_modifier(:post_action_users_list, post_actions, post)
+
     if !guardian.can_see_post_actors?(post.topic, post_action_type_id)
-      raise Discourse::InvalidAccess unless current_user
+      raise Discourse::InvalidAccess if current_user.blank?
       post_actions = post_actions.where(user_id: current_user.id)
     end
 
     action_type = PostActionType.types.key(post_action_type_id)
     total_count = post["#{action_type}_count"].to_i
-
+    post_actions = post_actions.to_a
     data = {
       post_action_users:
         serialize_data(
-          post_actions.to_a,
+          post_actions,
           PostActionUserSerializer,
-          unknown_user_ids: unknown_user_ids,
+          unknown_user_ids: current_user_muting_or_ignoring_users(post_actions.map(&:user_id)),
         ),
     }
 
@@ -55,4 +48,14 @@ class PostActionUsersController < ApplicationController
 
     render_json_dump(data)
   end
+
+  private
+
+  def current_user_muting_or_ignoring_users(user_ids)
+    return [] if current_user.blank?
+    UserCommScreener.new(
+      acting_user: current_user,
+      target_user_ids: user_ids,
+    ).actor_preventing_communication
+  end
 end

spec/requests/post_action_users_controller_spec.rb

@@ -138,4 +138,41 @@ RSpec.describe PostActionUsersController do
     expect(users.length).to eq(0)
     expect(total).to be_nil
   end
+
+  describe "when a plugin registers the :post_action_users_list modifier" do
+    before do
+      @post_action_1 = PostActionCreator.like(Fabricate(:user), post).post_action
+      @post_action_2 = PostActionCreator.like(Fabricate(:user), post).post_action
+    end
+
+    after { DiscoursePluginRegistry.clear_modifiers! }
+
+    it "allows the plugin to modify the post action query" do
+      excluded_post_action_ids = [@post_action_1.id]
+      Plugin::Instance
+        .new
+        .register_modifier(:post_action_users_list) do |query, modifier_post|
+          expect(modifier_post.id).to eq(post.id)
+          query.where("post_actions.id NOT IN (?)", excluded_post_action_ids)
+        end
+
+      get "/post_action_users.json",
+          params: {
+            id: post.id,
+            post_action_type_id: PostActionType.types[:like],
+          }
+      expect(response.status).to eq(200)
+      expect(response.parsed_body["post_action_users"].count).to eq(1)
+
+      DiscoursePluginRegistry.clear_modifiers!
+
+      get "/post_action_users.json",
+          params: {
+            id: post.id,
+            post_action_type_id: PostActionType.types[:like],
+          }
+      expect(response.status).to eq(200)
+      expect(response.parsed_body["post_action_users"].count).to eq(2)
+    end
+  end
 end