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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           {:meta, [property: "og:image:width", content: 150], []},
  42           {:meta, [property: "og:image:height", content: 150], []}
  43         ]
  44       else
  45         attachments
  46       end
  47   end
  48
  49   @impl Provider
  50   def build_tags(%{user: user}) do
  51     with truncated_bio = Utils.scrub_html_and_truncate(user.bio) do
  52       [
  53         {:meta,
  54          [
  55            property: "og:title",
  56            content: Utils.user_name_string(user)
  57          ], []},
  58         {:meta, [property: "og:url", content: user.uri || user.ap_id], []},
  59         {:meta, [property: "og:description", content: truncated_bio], []},
  60         {:meta, [property: "og:type", content: "article"], []},
  61         {:meta, [property: "og:image", content: MediaProxy.preview_url(User.avatar_url(user))], []},
  62         {:meta, [property: "og:image:width", content: 150], []},
  63         {:meta, [property: "og:image:height", content: 150], []}
  64       ]
  65     end
  66   end
  67
  68   defp build_attachments(%{data: %{"attachment" => attachments}}) do
  69     Enum.reduce(attachments, [], fn attachment, acc ->
  70       rendered_tags =
  71         Enum.reduce(attachment["url"], [], fn url, acc ->
  72           # TODO: Whatsapp only wants JPEG or PNGs. It seems that if we add a second og:image
  73           # object when a Video or GIF is attached it will display that in Whatsapp Rich Preview.
  74           case Utils.fetch_media_type(@media_types, url["mediaType"]) do
  75             "audio" ->
  76               [
  77                 {:meta, [property: "og:audio", content: MediaProxy.url(url["href"])], []}
  78                 | acc
  79               ]
  80
  81             # Not using preview_url for this. It saves bandwidth, but the image dimensions will be wrong.
  82             # We generate it on the fly and have no way to capture or analyze the image to get the dimensions.
  83             # This can be an issue for apps/FEs rendering images in timelines too, but you can get clever with
  84             # the aspect ratio metadata as a workaround.
  85             "image" ->
  86               [
  87                 {:meta, [property: "og:image", content: MediaProxy.url(url["href"])], []},
  88                 {:meta, [property: "og:image:alt", content: attachment["name"]], []}
  89                 | acc
  90               ]
  91               |> maybe_add_dimensions(url)
  92
  93             "video" ->
  94               [
  95                 {:meta, [property: "og:video", content: MediaProxy.url(url["href"])], []}
  96                 | acc
  97               ]
  98               |> maybe_add_dimensions(url)
  99
 100             _ ->
 101               acc
 102           end
 103         end)
 104
 105       acc ++ rendered_tags
 106     end)
 107   end
 108
 109   defp build_attachments(_), do: []
 110
 111   # We can use url["mediaType"] to dynamically fill the metadata
 112   defp maybe_add_dimensions(metadata, url) do
 113     type = url["mediaType"] |> String.split("/") |> List.first()
 114
 115     cond do
 116       !is_nil(url["height"]) && !is_nil(url["width"]) ->
 117         metadata ++
 118           [
 119             {:meta, [property: "og:#{type}:width", content: "#{url["width"]}"], []},
 120             {:meta, [property: "og:#{type}:height", content: "#{url["height"]}"], []}
 121           ]
 122
 123       true ->
 124         metadata
 125     end
 126   end
 127 end