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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 defmodule Pleroma.Web.Metadata.Providers.OpenGraph do
   5   alias Pleroma.Web.Metadata.Providers.Provider
   6   alias Pleroma.Web.Metadata
   7   alias Pleroma.{HTML, Formatter, User}
   8   alias Pleroma.Web.MediaProxy
   9
  10   @behaviour Provider
  11
  12   @impl Provider
  13   def build_tags(%{
  14         activity: %{data: %{"object" => %{"id" => object_id}}} = activity,
  15         user: user
  16       }) do
  17     attachments = build_attachments(activity)
  18     scrubbed_content = scrub_html_and_truncate(activity)
  19     # Zero width space
  20     content =
  21       if scrubbed_content != "" and scrubbed_content != "\u200B" do
  22         ": “" <> scrubbed_content <> "”"
  23       else
  24         ""
  25       end
  26
  27     # Most previews only show og:title which is inconvenient. Instagram
  28     # hacks this by putting the description in the title and making the
  29     # description longer prefixed by how many likes and shares the post
  30     # has. Here we use the descriptive nickname in the title, and expand
  31     # the full account & nickname in the description. We also use the cute^Wevil
  32     # smart quotes around the status text like Instagram, too.
  33     [
  34       {:meta,
  35        [
  36          property: "og:title",
  37          content: "#{user.name}" <> content
  38        ], []},
  39       {:meta, [property: "og:url", content: object_id], []},
  40       {:meta,
  41        [
  42          property: "og:description",
  43          content: "#{user_name_string(user)}" <> content
  44        ], []},
  45       {:meta, [property: "og:type", content: "website"], []}
  46     ] ++
  47       if attachments == [] or Metadata.activity_nsfw?(activity) do
  48         [
  49           {:meta, [property: "og:image", content: attachment_url(User.avatar_url(user))], []},
  50           {:meta, [property: "og:image:width", content: 150], []},
  51           {:meta, [property: "og:image:height", content: 150], []}
  52         ]
  53       else
  54         attachments
  55       end
  56   end
  57
  58   @impl Provider
  59   def build_tags(%{user: user}) do
  60     with truncated_bio = scrub_html_and_truncate(user.bio || "") do
  61       [
  62         {:meta,
  63          [
  64            property: "og:title",
  65            content: user_name_string(user)
  66          ], []},
  67         {:meta, [property: "og:url", content: User.profile_url(user)], []},
  68         {:meta, [property: "og:description", content: truncated_bio], []},
  69         {:meta, [property: "og:type", content: "website"], []},
  70         {:meta, [property: "og:image", content: attachment_url(User.avatar_url(user))], []},
  71         {:meta, [property: "og:image:width", content: 150], []},
  72         {:meta, [property: "og:image:height", content: 150], []}
  73       ]
  74     end
  75   end
  76
  77   defp build_attachments(%{data: %{"object" => %{"attachment" => attachments}}} = _activity) do
  78     Enum.reduce(attachments, [], fn attachment, acc ->
  79       rendered_tags =
  80         Enum.reduce(attachment["url"], [], fn url, acc ->
  81           media_type =
  82             Enum.find(["image", "audio", "video"], fn media_type ->
  83               String.starts_with?(url["mediaType"], media_type)
  84             end)
  85
  86           # TODO: Add additional properties to objects when we have the data available.
  87           # Also, Whatsapp only wants JPEG or PNGs. It seems that if we add a second og:image
  88           # object when a Video or GIF is attached it will display that in the Whatsapp Rich Preview.
  89           case media_type do
  90             "audio" ->
  91               [
  92                 {:meta, [property: "og:" <> media_type, content: attachment_url(url["href"])], []}
  93                 | acc
  94               ]
  95
  96             "image" ->
  97               [
  98                 {:meta, [property: "og:" <> media_type, content: attachment_url(url["href"])],
  99                  []},
 100                 {:meta, [property: "og:image:width", content: 150], []},
 101                 {:meta, [property: "og:image:height", content: 150], []}
 102                 | acc
 103               ]
 104
 105             "video" ->
 106               [
 107                 {:meta, [property: "og:" <> media_type, content: attachment_url(url["href"])], []}
 108                 | acc
 109               ]
 110
 111             _ ->
 112               acc
 113           end
 114         end)
 115
 116       acc ++ rendered_tags
 117     end)
 118   end
 119
 120   defp scrub_html_and_truncate(%{data: %{"object" => %{"content" => content}}} = activity) do
 121     content
 122     # html content comes from DB already encoded, decode first and scrub after
 123     |> HtmlEntities.decode()
 124     |> String.replace(~r/<br\s?\/?>/, " ")
 125     |> HTML.get_cached_stripped_html_for_object(activity, __MODULE__)
 126     |> Formatter.truncate()
 127   end
 128
 129   defp scrub_html_and_truncate(content) when is_binary(content) do
 130     content
 131     # html content comes from DB already encoded, decode first and scrub after
 132     |> HtmlEntities.decode()
 133     |> String.replace(~r/<br\s?\/?>/, " ")
 134     |> HTML.strip_tags()
 135     |> Formatter.truncate()
 136   end
 137
 138   defp attachment_url(url) do
 139     MediaProxy.url(url)
 140   end
 141
 142   defp user_name_string(user) do
 143     "#{user.name} " <>
 144       if user.local do
 145         "(@#{user.nickname}@#{Pleroma.Web.Endpoint.host()})"
 146       else
 147         "(@#{user.nickname})"
 148       end
 149   end
 150 end