defmodule Frenzy.Pipeline.Extractor.WhateverScalzi do
  @moduledoc """
  Extractor for https://whatever.scalzi.com
  """

  alias Frenzy.Pipeline.Extractor
  @behaviour Extractor

  @impl Extractor
  def extract(html_tree) do
    case get_article_content(html_tree) do
      nil ->
        {:error, "no matching elements"}

      elem ->
        {:ok, elem}
    end
  end

  defp get_article_content(html_tree) do
    # there's no element that contains only the post content
    # .postarea contains the headline, post content, social media buttons, and comments
    case Floki.find(html_tree, ".postarea") do
      [{_tag, _attrs, postarea_children}] ->
        Enum.split_while(postarea_children, fn
          {"h1", _, _} -> true
          _ -> false
        end)
        |> case do
          {_before_headline, [_headline | rest]} ->
            {article_content, _rest} =
              Enum.split_while(rest, fn
                {"div", attrs, _} = el ->
                  class = Floki.attribute(el, "class") |> List.first()

                  if {"id", "comments"} in attrs do
                    false
                  else
                    is_nil(class) || !String.contains?(class, "sharedaddy")
                  end

                _ ->
                  true
              end)

            Extractor.Util.strip_wp_lazy_loading(article_content)

          _ ->
            nil
        end

      _ ->
        nil
    end
  end
end