Refactor comment tree calculation using a PORO

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