Refactor comment tree calculation using a PORO

app/controllers/concerns/commentable_actions.rb

@@ -16,11 +16,8 @@ module CommentableActions
   def show
     set_resource_votes(resource)
     @commentable = resource
-    @root_comments = resource.comments.roots.send("sort_by_#{@current_order}").page(params[:page]).per(10).for_render
+    @comment_tree = CommentTree.new(@commentable, params[:page], @current_order)
-    @comments = @root_comments.inject([]){|all, root| all + Comment.descendants_of(root).for_render}
+    set_comment_flags(@comment_tree.comments)
-    @all_visible_comments = @root_comments + @comments
-
-    set_comment_flags(@all_visible_comments)
     set_resource_instance
   end
 

app/helpers/comments_helper.rb

@@ -12,14 +12,9 @@ module CommentsHelper
     parent_id.blank? ? dom_id(commentable) : "comment_#{parent_id}"
   end
 
-  def select_children(comments, parent)
+  def child_comments_of(parent)
-    return [] if comments.blank?
+    return [] unless @comment_tree
-    comments.select{|c| c.parent_id == parent.id}
+    @comment_tree.children_of(parent)
-  end
-
-  def count_children(comments, parent)
-    return 0 if comments.blank?
-    comments.count{ |c| c.parent_id == parent.id }
   end
 
   def user_level_class(comment)

app/views/comments/_comment.html.erb

@@ -3,7 +3,7 @@
   	<div id="<%= dom_id(comment) %>" class="comment small-12 column">
 
       <% if comment.hidden? || comment.user.hidden? %>
-        <% if count_children(@comments, comment) > 0 %>
+        <% if child_comments_of(comment).size > 0 %>
           <div class="is-deleted">
             <p><%= t("comments.comment.deleted") %></p>
           </div>
@@ -73,7 +73,7 @@
           </span>
 
           <div class="reply">
-            <%= t("comments.comment.responses", count: count_children(@comments, comment)) %>
+            <%= t("comments.comment.responses", count: child_comments_of(comment).size) %>
 
             <% if user_signed_in? %>
               <span class="divider">&nbsp;|&nbsp;</span>
@@ -88,7 +88,7 @@
         </div>
       <% end %>
       <div class="comment-children">
-        <% select_children(@comments, comment).each do |child| %>
+        <% child_comments_of(comment).each do |child| %>
           <%= render 'comments/comment', comment: child %>
         <% end %>
       </div>

app/views/debates/_comments.html.erb

@@ -1,4 +1,4 @@
-<% cache [locale_and_user_status, @current_order, commentable_cache_key(@debate), @all_visible_comments, @all_visible_comments.map(&:author), @debate.comments_count, @comment_flags] do %>
+<% cache [locale_and_user_status, @current_order, commentable_cache_key(@debate), @comment_tree.comments, @comment_tree.comment_authors, @debate.comments_count, @comment_flags] do %>
   <section class="row-full comments">
     <div class="row">
       <div id="comments" class="small-12 column">
@@ -21,10 +21,10 @@
           </div>
         <% end %>
 
-        <% @root_comments.each do |comment| %>
+        <% @comment_tree.root_comments.each do |comment| %>
           <%= render 'comments/comment', comment: comment  %>
         <% end %>
-        <%= paginate @root_comments %>
+        <%= paginate @comment_tree.root_comments %>
       </div>
     </div>
   </section>

app/views/proposals/_comments.html.erb

@@ -1,4 +1,4 @@
-<% cache [locale_and_user_status, commentable_cache_key(@proposal), @current_order, @all_visible_comments, @all_visible_comments.map(&:author), @proposal.comments_count, @comment_flags] do %>
+<% cache [locale_and_user_status, @current_order, commentable_cache_key(@proposal), @comment_tree.comments, @comment_tree.comment_authors, @proposal.comments_count, @comment_flags] do %>
   <section class="row-full comments">
     <div class="row">
       <div id="comments" class="small-12 column">
@@ -22,10 +22,10 @@
           </div>
         <% end %>
 
-        <% @root_comments.each do |comment| %>
+        <% @comment_tree.root_comments.each do |comment| %>
           <%= render 'comments/comment', comment: comment  %>
         <% end %>
-        <%= paginate @root_comments %>
+        <%= paginate @comment_tree.root_comments %>
       </div>
     </div>
   </section>

lib/comment_tree.rb

@@ -0,0 +1,28 @@
+class CommentTree
+
+  ROOT_COMMENTS_PER_PAGE = 10
+
+  attr_accessor :root_comments, :comments
+
+  def initialize(commentable, page, order = 'confidence_score')
+    @root_comments = commentable.comments.roots.send("sort_by_#{order}").page(page).per(ROOT_COMMENTS_PER_PAGE).for_render
+
+    root_descendants = @root_comments.each_with_object([]) do |root, col|
+      col += Comment.descendants_of(root).send("sort_by_#{order}").for_render.to_a
+    end
+
+    @comments = root_comments + root_descendants
+
+    @comments_by_parent_id = @comments.each_with_object({}) do |comment, col|
+      (col[comment.parent_id] ||= []) << comment
+    end
+  end
+
+  def children_of(parent)
+    @comments_by_parent_id[parent.id] || []
+  end
+
+  def comment_authors
+    comments.map(&:author)
+  end
+end