modqueue: add sidebar.

Add a sidebar to the modqueue page that shows the following information:

* Number of pending and flagged posts.
* Number of posts disapproved for poor quality or breaking rules.
* Top uploaders in the queue.
* Top artist, copyright, and character tags in the queue.

app/controllers/modqueue_controller.rb

@@ -1,9 +1,22 @@
 class ModqueueController < ApplicationController
   respond_to :html, :json, :xml
   before_action :approver_only
+  layout "sidebar"
 
   def index
-    @posts = Post.includes(:appeals, :disapprovals, :uploader, flags: [:creator]).reorder(id: :asc).pending_or_flagged.available_for_moderation(search_params[:hidden]).tag_match(search_params[:tags]).paginated_search(params, count_pages: true)
+    @posts = Post.includes(:appeals, :disapprovals, :uploader, flags: [:creator]).pending_or_flagged.available_for_moderation(search_params[:hidden]).tag_match(search_params[:tags])
+
+    @pending_post_count = @posts.pending.count
+    @flagged_post_count = @posts.flagged.count
+    @disapproval_reasons = PostDisapproval.where(post: @posts).where.not(reason: "disinterest").group(:reason).order(count: :desc).distinct.count(:post_id)
+    @uploaders = @posts.reorder(nil).group(:uploader).order(count: :desc).limit(20).count
+
+    @tags = RelatedTagCalculator.frequent_tags_for_post_relation(@posts)
+    @artist_tags = @tags.select { |tag| tag.category == Tag.categories.artist }.sort_by(&:overlap_count).reverse.take(10)
+    @copyright_tags = @tags.select { |tag| tag.category == Tag.categories.copyright }.sort_by(&:overlap_count).reverse.take(10)
+    @character_tags = @tags.select { |tag| tag.category == Tag.categories.character }.sort_by(&:overlap_count).reverse.take(10)
+
+    @posts = @posts.reorder(id: :asc).paginated_search(params, count_pages: true)
     respond_with(@posts)
   end
 end