something-erlang/lib/something_erlang/awful_api/thread.ex

defmodule SomethingErlang.AwfulApi.Thread do
  require Logger

  alias SomethingErlang.AwfulApi.Client

  def compile(id, page, user) do
    doc = Client.thread_doc(id, page, user)
    html = Floki.parse_document!(doc)
    thread = Floki.find(html, "#thread") |> Floki.filter_out("table.post.ignored")


    title = Floki.find(html, "title") |> Floki.text()
    title = title |> String.replace(" - The Something Awful Forums", "")

    page_count =
      case Floki.find(html, "#content .pages.top option:last-of-type") |> Floki.text() do
        "" -> 1
        s -> String.to_integer(s)
      end

    posts = for post <- Floki.find(thread, "table.post") do
      %{
        userinfo: post |> userinfo(),
        postdate: post |> postdate(),
        postbody: post |> postbody()
      }
    end

    %{id: id,
      title: title,
      page: page,
      page_count: page_count,
      posts: posts}
  end

  defp userinfo(post) do
    user = Floki.find(post, "dl.userinfo")
    name = user |> Floki.find("dt") |> Floki.text()
    regdate = user |> Floki.find("dd.registered") |> Floki.text()
    title =
      user |> Floki.find("dd.title") |> List.first()
      |> Floki.children() |> Floki.raw_html()

    %{
      name: name,
      regdate: regdate,
      title: title
    }
  end

  defp postdate(post) do
    date =
      Floki.find(post, "td.postdate")
      |> Floki.find("td.postdate") |> Floki.text()

    [month_text, day, year, hours, minutes] = date
    |> String.split(~r{[\s,:]}, trim: true)
    |> Enum.drop(1)

    month = 1 + Enum.find_index(["Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"],
      fn m -> m == month_text end)
    NaiveDateTime.new!(year |> String.to_integer(), month, day |> String.to_integer(),
      hours |> String.to_integer(), minutes |> String.to_integer(), 0)
  end

  defp postbody(post) do
    body =
      Floki.find(post, "td.postbody")
      |> List.first()
      |> Floki.filter_out(:comment)

    Floki.traverse_and_update(body, fn
      {"img", attrs, []} -> transform(:img, attrs)
      {"a", attrs, children} -> transform(:a, attrs, children)
      other -> other
    end)
    |> Floki.children()
    |> Floki.raw_html()
  end

  defp transform(elem, attr, children \\ [])

  defp transform(:img, attrs, _children) do
    {"class", class} = List.keyfind(attrs, "class", 0, {"class", ""})
    if class == "sa-smilie" do
      {"img", attrs, []}
    else
      t_attrs = List.keyreplace(attrs, "class", 0, {"class", "img-responsive"})
      {"img", [{"loading", "lazy"} | t_attrs], []}
    end
  end

  defp transform(:a, attrs, children) do
    {"href", href} = List.keyfind(attrs, "href", 0, {"href", ""})
    cond do
      # skip internal links
      String.starts_with?(href, "/") ->
        {"a", [{"href", href}], children}

      # mp4
      String.ends_with?(href, ".mp4") ->
        transform_link(:mp4, href)

      # gifv
      String.ends_with?(href, ".gifv") ->
        transform_link(:gifv, href)

      # youtube
      String.starts_with?(href, "https://www.youtube.com/watch") ->
        transform_link(:ytlong, href)

      String.starts_with?(href, "https://youtu.be/") ->
        transform_link(:ytshort, href)

      true ->
        Logger.debug "no transform for #{href}"
        {"a", [{"href", href}], children}
    end
  end

  defp transform_link(:mp4, href),
    do: {"div", [{"class", "responsive-embed"}],
         [{"video", [{"class", "img-responsive"}, {"controls", ""}],
           [{"source", [{"src", href}, {"type", "video/mp4"}], []}]
          }]
  }

  defp transform_link(:gifv, href),
    do: {"div", [{"class", "responsive-embed"}],
         [{"video", [{"class", "img-responsive"}, {"controls", ""}],
           [{"source", [{"src", String.replace(href, ".gifv", ".webm")},
                        {"type", "video/webm"}], []},
            {"source", [{"src", String.replace(href, ".gifv", ".mp4")},
                        {"type", "video/mp4"}], []}]
          }]
  }

  defp transform_link(:ytlong, href) do
    String.replace(href, "/watch?v=", "/embed/")
    |> youtube_iframe()
  end

  defp transform_link(:ytshort, href) do
    String.replace(href, "youtu.be/", "www.youtube.com/embed/")
    |> youtube_iframe()
  end

  defp youtube_iframe(src),
    do: {"div", [{"class", "responsive-embed"}],
         [{"iframe",
           [
             {"class", "youtube-player"},
             {"loading", "lazy"},
             {"allow", "fullscreen"},
             {"src", src}
           ], []}
         ]}

end