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   1 # Pleroma: A lightweight social networking server
   2 # Copyright © 2017-2021 Pleroma Authors <https://pleroma.social/>
   3 # SPDX-License-Identifier: AGPL-3.0-only
   4
   5 defmodule Pleroma.Web.Metadata.Providers.OpenGraph do
   6   alias Pleroma.User
   7   alias Pleroma.Web.MediaProxy
   8   alias Pleroma.Web.Metadata
   9   alias Pleroma.Web.Metadata.Providers.Provider
  10   alias Pleroma.Web.Metadata.Utils
  11
  12   @behaviour Provider
  13   @media_types ["image", "audio", "video"]
  14
  15   @impl Provider
  16   def build_tags(%{
  17         object: object,
  18         url: url,
  19         user: user
  20       }) do
  21     attachments = build_attachments(object)
  22     scrubbed_content = Utils.scrub_html_and_truncate(object)
  23
  24     [
  25       {:meta,
  26        [
  27          property: "og:title",
  28          content: Utils.user_name_string(user)
  29        ], []},
  30       {:meta, [property: "og:url", content: url], []},
  31       {:meta,
  32        [
  33          property: "og:description",
  34          content: scrubbed_content
  35        ], []},
  36       {:meta, [property: "og:type", content: "article"], []}
  37     ] ++
  38       if attachments == [] or Metadata.activity_nsfw?(object) do
  39         [
  40           {:meta, [property: "og:image", content: MediaProxy.preview_url(User.avatar_url(user))],
  41            []},
  42           {:meta, [property: "og:image:width", content: 150], []},
  43           {:meta, [property: "og:image:height", content: 150], []}
  44         ]
  45       else
  46         attachments
  47       end
  48   end
  49
  50   @impl Provider
  51   def build_tags(%{user: user}) do
  52     with truncated_bio = Utils.scrub_html_and_truncate(user.bio) do
  53       [
  54         {:meta,
  55          [
  56            property: "og:title",
  57            content: Utils.user_name_string(user)
  58          ], []},
  59         {:meta, [property: "og:url", content: user.uri || user.ap_id], []},
  60         {:meta, [property: "og:description", content: truncated_bio], []},
  61         {:meta, [property: "og:type", content: "article"], []},
  62         {:meta, [property: "og:image", content: MediaProxy.preview_url(User.avatar_url(user))],
  63          []},
  64         {:meta, [property: "og:image:width", content: 150], []},
  65         {:meta, [property: "og:image:height", content: 150], []}
  66       ]
  67     end
  68   end
  69
  70   defp build_attachments(%{data: %{"attachment" => attachments}}) do
  71     Enum.reduce(attachments, [], fn attachment, acc ->
  72       rendered_tags =
  73         Enum.reduce(attachment["url"], [], fn url, acc ->
  74           # TODO: Whatsapp only wants JPEG or PNGs. It seems that if we add a second og:image
  75           # object when a Video or GIF is attached it will display that in Whatsapp Rich Preview.
  76           case Utils.fetch_media_type(@media_types, url["mediaType"]) do
  77             "audio" ->
  78               [
  79                 {:meta, [property: "og:audio", content: MediaProxy.url(url["href"])], []}
  80                 | acc
  81               ]
  82
  83             # Not using preview_url for this. It saves bandwidth, but the image dimensions will be wrong.
  84             # We generate it on the fly and have no way to capture or analyze the image to get the dimensions.
  85             # This can be an issue for apps/FEs rendering images in timelines too, but you can get clever with
  86             # the aspect ratio metadata as a workaround.
  87             "image" ->
  88               [
  89                 {:meta, [property: "og:image", content: MediaProxy.url(url["href"])], []},
  90                 {:meta, [property: "og:image:alt", content: attachment["name"]], []}
  91                 | acc
  92               ]
  93               |> maybe_add_dimensions(url)
  94
  95             "video" ->
  96               [
  97                 {:meta, [property: "og:video", content: MediaProxy.url(url["href"])], []}
  98                 | acc
  99               ]
 100               |> maybe_add_dimensions(url)
 101               |> maybe_add_video_thumbnail(url)
 102
 103             _ ->
 104               acc
 105           end
 106         end)
 107
 108       acc ++ rendered_tags
 109     end)
 110   end
 111
 112   defp build_attachments(_), do: []
 113
 114   # We can use url["mediaType"] to dynamically fill the metadata
 115   defp maybe_add_dimensions(metadata, url) do
 116     type = url["mediaType"] |> String.split("/") |> List.first()
 117
 118     cond do
 119       !is_nil(url["height"]) && !is_nil(url["width"]) ->
 120         metadata ++
 121           [
 122             {:meta, [property: "og:#{type}:width", content: "#{url["width"]}"], []},
 123             {:meta, [property: "og:#{type}:height", content: "#{url["height"]}"], []}
 124           ]
 125
 126       true ->
 127         metadata
 128     end
 129   end
 130
 131   defp maybe_add_video_thumbnail(metadata, url) do
 132     cond do
 133       Pleroma.Config.get([:media_preview_proxy, :enabled], false) ->
 134         metadata ++
 135           [
 136             {:meta, [property: "og:image:width", content: "#{url["width"]}"], []},
 137             {:meta, [property: "og:image:height", content: "#{url["height"]}"], []},
 138             {:meta, [property: "og:image", content: MediaProxy.preview_url(url["href"])], []}
 139           ]
 140
 141       true ->
 142         metadata
 143     end
 144   end
 145 end