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   1 # Pleroma: A lightweight social networking server
   2 # Copyright © 2017-2019 Pleroma Authors <https://pleroma.social/>
   3 # SPDX-License-Identifier: AGPL-3.0-only
   4
   5 defmodule Pleroma.Web.RichMedia.Parser do
   6   @parsers [
   7     Pleroma.Web.RichMedia.Parsers.OGP,
   8     Pleroma.Web.RichMedia.Parsers.TwitterCard,
   9     Pleroma.Web.RichMedia.Parsers.OEmbed
  10   ]
  11
  12   def parse(nil), do: {:error, "No URL provided"}
  13
  14   if Mix.env() == :test do
  15     def parse(url), do: parse_url(url)
  16   else
  17     def parse(url) do
  18       try do
  19         Cachex.fetch!(:rich_media_cache, url, fn _ ->
  20           {:commit, parse_url(url)}
  21         end)
  22       rescue
  23         e ->
  24           {:error, "Cachex error: #{inspect(e)}"}
  25       end
  26     end
  27   end
  28
  29   defp parse_url(url) do
  30     try do
  31       {:ok, %Tesla.Env{body: html}} = Pleroma.HTTP.get(url, [], adapter: [pool: :media])
  32
  33       html |> maybe_parse() |> clean_parsed_data() |> check_parsed_data()
  34     rescue
  35       e ->
  36         {:error, "Parsing error: #{inspect(e)}"}
  37     end
  38   end
  39
  40   defp maybe_parse(html) do
  41     Enum.reduce_while(@parsers, %{}, fn parser, acc ->
  42       case parser.parse(html, acc) do
  43         {:ok, data} -> {:halt, data}
  44         {:error, _msg} -> {:cont, acc}
  45       end
  46     end)
  47   end
  48
  49   defp check_parsed_data(%{title: title} = data) when is_binary(title) and byte_size(title) > 0 do
  50     {:ok, data}
  51   end
  52
  53   defp check_parsed_data(data) do
  54     {:error, "Found metadata was invalid or incomplete: #{inspect(data)}"}
  55   end
  56
  57   defp clean_parsed_data(data) do
  58     data
  59     |> Enum.reject(fn {key, val} ->
  60       with {:ok, _} <- Jason.encode(%{key => val}) do
  61         false
  62       else
  63         _ -> true
  64       end
  65     end)
  66     |> Map.new()
  67   end
  68 end