fetch2.rb

node_index.each do |node_id, data|
  # This is a root node, no processing to do.
  next if data[:node].ancestry.nil?

  # Here we check the nesting depth to make sure it is not over the max
  # allowed depth.
  assigned_parent_id = nil
  if data[:node].depth > Comment::MAX_DEPTH
    # Comment is nested deeper than the max allowed depth, which means we
    # convert it to a "reply to" style comment and move it up the tree to
    # the max depth.
    #
    # We explicitly use ancestor_ids here because it does not generate a
    # database query.
    assigned_parent_id = data[:node].ancestor_ids[Comment::MAX_DEPTH - 1]
    
    # Since we have that handy index of comments, we can easily reference the
    # comment that this one is a reply to.
    data[:reply_to] = node_index[data[:node].parent_id][:node]
  else
    # If we're not over the max nesting depth, we can just proceed as usual.
    assigned_parent_id = data[:node].parent_id
  end

  # We store a reference to the parent comment ID for later use
  data[:parent] = assigned_parent_id
  
  # And finally, we add this comment to the parent comments children. This is
  # where the structure of the tree starts to take form.
  node_index[assigned_parent_id][:children].unshift data
end