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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.Metadata.Providers.OpenGraph do
   6   alias Pleroma.User
   7   alias Pleroma.Web.Metadata
   8   alias Pleroma.Web.Metadata.Providers.Provider
   9   alias Pleroma.Web.Metadata.Utils
  10
  11   @behaviour Provider
  12   @media_types ["image", "audio", "video"]
  13
  14   @impl Provider
  15   def build_tags(%{
  16         object: object,
  17         url: url,
  18         user: user
  19       }) do
  20     attachments = build_attachments(object)
  21     scrubbed_content = Utils.scrub_html_and_truncate(object)
  22     # Zero width space
  23     content =
  24       if scrubbed_content != "" and scrubbed_content != "\u200B" do
  25         ": “" <> scrubbed_content <> "”"
  26       else
  27         ""
  28       end
  29
  30     # Most previews only show og:title which is inconvenient. Instagram
  31     # hacks this by putting the description in the title and making the
  32     # description longer prefixed by how many likes and shares the post
  33     # has. Here we use the descriptive nickname in the title, and expand
  34     # the full account & nickname in the description. We also use the cute^Wevil
  35     # smart quotes around the status text like Instagram, too.
  36     [
  37       {:meta,
  38        [
  39          property: "og:title",
  40          content: "#{user.name}" <> content
  41        ], []},
  42       {:meta, [property: "og:url", content: url], []},
  43       {:meta,
  44        [
  45          property: "og:description",
  46          content: "#{Utils.user_name_string(user)}" <> content
  47        ], []},
  48       {:meta, [property: "og:type", content: "website"], []}
  49     ] ++
  50       if attachments == [] or Metadata.activity_nsfw?(object) do
  51         [
  52           {:meta, [property: "og:image", content: Utils.attachment_url(User.avatar_url(user))],
  53            []},
  54           {:meta, [property: "og:image:width", content: 150], []},
  55           {:meta, [property: "og:image:height", content: 150], []}
  56         ]
  57       else
  58         attachments
  59       end
  60   end
  61
  62   @impl Provider
  63   def build_tags(%{user: user}) do
  64     with truncated_bio = Utils.scrub_html_and_truncate(user.bio || "") do
  65       [
  66         {:meta,
  67          [
  68            property: "og:title",
  69            content: Utils.user_name_string(user)
  70          ], []},
  71         {:meta, [property: "og:url", content: user.uri || user.ap_id], []},
  72         {:meta, [property: "og:description", content: truncated_bio], []},
  73         {:meta, [property: "og:type", content: "website"], []},
  74         {:meta, [property: "og:image", content: Utils.attachment_url(User.avatar_url(user))], []},
  75         {:meta, [property: "og:image:width", content: 150], []},
  76         {:meta, [property: "og:image:height", content: 150], []}
  77       ]
  78     end
  79   end
  80
  81   defp build_attachments(%{data: %{"attachment" => attachments}}) do
  82     Enum.reduce(attachments, [], fn attachment, acc ->
  83       rendered_tags =
  84         Enum.reduce(attachment["url"], [], fn url, acc ->
  85           # TODO: Add additional properties to objects when we have the data available.
  86           # Also, Whatsapp only wants JPEG or PNGs. It seems that if we add a second og:image
  87           # object when a Video or GIF is attached it will display that in Whatsapp Rich Preview.
  88           case Utils.fetch_media_type(@media_types, url["mediaType"]) do
  89             "audio" ->
  90               [
  91                 {:meta, [property: "og:audio", content: Utils.attachment_url(url["href"])], []}
  92                 | acc
  93               ]
  94
  95             "image" ->
  96               [
  97                 {:meta, [property: "og:image", content: Utils.attachment_url(url["href"])], []},
  98                 {:meta, [property: "og:image:width", content: 150], []},
  99                 {:meta, [property: "og:image:height", content: 150], []}
 100                 | acc
 101               ]
 102
 103             "video" ->
 104               [
 105                 {:meta, [property: "og:video", content: Utils.attachment_url(url["href"])], []}
 106                 | acc
 107               ]
 108
 109             _ ->
 110               acc
 111           end
 112         end)
 113
 114       acc ++ rendered_tags
 115     end)
 116   end
 117
 118   defp build_attachments(_), do: []
 119 end