defmodule Urlpreview.Parser do

  def parse(%{body: body, request_url: url, real_url: real_url}) do
    %{
        title: get_title(body),
        description: get_description(body),
        images: get_images(body) |> add_images_base_url(url),
        url: url,
        real_url: get_real_url(body, real_url)
      }
  end

  defp get_real_url(html, url) do
    Floki.attribute(html, "meta[property=\"og:url\"]", "content") ++ [url]
      |> remove_empty_list_items
      |> Enum.at(0)
  end

  defp add_images_base_url(image_urls, base_url) do
    parsed_url = Fuzzyurl.from_string(base_url)
    Enum.map(image_urls, fn(x) ->
      x |> append_protocol_and_host(parsed_url)
    end)
  end

  defp append_protocol_and_host(url, parsed_url) do
    if !Regex.match?(~r/^(http:\/\/|https:\/\/)/, url) do
      if !Regex.match?(~r/^\/\//, url) do
        if String.at(url, 0) == "/" do
          "#{parsed_url.protocol}://#{parsed_url.hostname}#{url}"
        else
          "#{parsed_url.protocol}://#{parsed_url.hostname}/#{url}"
        end
      else
        "#{parsed_url.protocol}:#{url}"
      end
    else
      url
    end
  end

  defp get_description(html) do
    Floki.attribute(html, "meta[property=\"og:description\"]", "content") ++
      Floki.attribute(html, "meta[name=\"description\"]", "content")
      |> remove_empty_list_items
      |> Enum.at(0)
  end

  defp get_title(html) do
    Floki.attribute(html, "meta[property=\"og:site_name\"]", "content") ++
      [Floki.find(html, "title") |> Floki.text]
      |> remove_empty_list_items
      |> Enum.at(0)
  end

  defp get_images(html) do
    Floki.attribute(html, "meta[property=\"og:image\"]", "content") ++
      Floki.attribute(html, "meta[property=\"twitter:image\"]", "content") ++
      Floki.attribute(html, "meta[itemprop='image']", "content")
      |> remove_empty_list_items
  end

  defp remove_empty_list_items(list) do
    Enum.filter(list, fn(x) -> x != nil and x != "" end)
  end
end