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   1 # Pleroma: A lightweight social networking server
   2 # Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
   3 # SPDX-License-Identifier: AGPL-3.0-only
   4
   5 defmodule Pleroma.Web.RichMedia.Parsers.MetaTagsParser do
   6   def parse(data, html, prefix, key_name, value_name \\ "content") do
   7     html
   8     |> get_elements(key_name, prefix)
   9     |> Enum.reduce(data, fn el, acc ->
  10       attributes = normalize_attributes(el, prefix, key_name, value_name)
  11
  12       Map.merge(acc, attributes)
  13     end)
  14     |> maybe_put_title(html)
  15   end
  16
  17   defp get_elements(html, key_name, prefix) do
  18     html |> Floki.find("meta[#{key_name}^='#{prefix}:']")
  19   end
  20
  21   defp normalize_attributes(html_node, prefix, key_name, value_name) do
  22     {_tag, attributes, _children} = html_node
  23
  24     data =
  25       Map.new(attributes, fn {name, value} ->
  26         {name, String.trim_leading(value, "#{prefix}:")}
  27       end)
  28
  29     %{data[key_name] => data[value_name]}
  30   end
  31
  32   defp maybe_put_title(%{"title" => _} = meta, _), do: meta
  33
  34   defp maybe_put_title(meta, html) when meta != %{} do
  35     case get_page_title(html) do
  36       "" -> meta
  37       title -> Map.put_new(meta, "title", title)
  38     end
  39   end
  40
  41   defp maybe_put_title(meta, _), do: meta
  42
  43   defp get_page_title(html) do
  44     Floki.find(html, "html head title") |> List.first() |> Floki.text()
  45   end
  46 end