related tags: eliminate recent_tags cookie (#3955).

app/controllers/posts_controller.rb

@@ -46,7 +46,6 @@ class PostsController < ApplicationController
     @post = Post.find(params[:id])
 
     @post.update(post_params) if @post.visible?
-    save_recent_tags
     respond_with_post_after_update(@post)
   end
 
@@ -96,15 +95,6 @@ private
     params[:tags] || (params[:post] && params[:post][:tags])
   end
 
-  def save_recent_tags
-    if @post
-      tags = Tag.scan_tags(@post.tag_string)
-      tags = (TagAlias.to_aliased(tags) + Tag.scan_tags(cookies[:recent_tags])).uniq.slice(0, 30)
-      cookies[:recent_tags] = tags.join(" ")
-      cookies[:recent_tags_with_categories] = Tag.categories_for(tags).to_a.flatten.join(" ")
-    end
-  end
-
   def respond_with_post_after_update(post)
     respond_with(post) do |format|
       format.html do

app/controllers/uploads_controller.rb

@@ -58,21 +58,11 @@ class UploadsController < ApplicationController
       flash[:notice] = @service.warnings.join(".\n \n")
     end
 
-    save_recent_tags
     respond_with(@upload)
   end
 
   private
 
-  def save_recent_tags
-    if @upload
-      tags = Tag.scan_tags(@upload.tag_string)
-      tags = (TagAlias.to_aliased(tags) + Tag.scan_tags(cookies[:recent_tags])).compact.uniq.slice(0, 30)
-      cookies[:recent_tags] = tags.join(" ")
-      cookies[:recent_tags_with_categories] = Tag.categories_for(tags).to_a.flatten.join(" ")
-    end
-  end
-
   def upload_params
     permitted_params = %i[
       file source tag_string rating status parent_id artist_commentary_title

app/logical/related_tag_query.rb

@@ -26,6 +26,17 @@ class RelatedTagQuery
     end
   end
 
+  # Returns the top 20 most frequently added tags within the last 20 edits made by the user in the last hour.
+  def recent_tags(since: 1.hour.ago, max_edits: 20, max_tags: 20)
+    return [] unless user.present? && PostArchive.enabled?
+
+    versions = PostArchive.where(updater_id: user.id).where("updated_at > ?", since).order(id: :desc).limit(max_edits)
+    tags = versions.flat_map { |v| v.diff[:added_tags] }
+    tags = tags.reject { |tag| Tag.is_metatag?(tag) }
+    tags = tags.group_by(&:itself).transform_values(&:size).sort_by { |tag, count| [-count, tag] }.map(&:first)
+    tags.take(max_tags)
+  end
+
   def favorite_tags
     user&.favorite_tags.to_s.split
   end

app/views/related_tags/_related_tags.html.erb

@@ -2,7 +2,7 @@
 
 <div id="related-tags" class="related-tags">
   <% if local_assigns[:related_tags] %>
-    <%= render "tag_column", tags: cookies[:recent_tags].to_s.split, title: "Recent" %>
+    <%= render "tag_column", tags: related_tags.recent_tags, title: "Recent" %>
     <%= render "tag_column", tags: related_tags.favorite_tags, title: "Frequent" %>
     <%= render "tag_column", tags: related_tags.tags, class: "general-related-tags-column", title: related_tags.pretty_name %>
     <%= render "tag_column", tags: related_tags.translated_tags, title: "Translated Tags" %>