twitter_card.ex (4920B)
- # Pleroma: A lightweight social networking server
- # Copyright © 2017-2022 Pleroma Authors <https://pleroma.social/>
- # SPDX-License-Identifier: AGPL-3.0-only
- defmodule Pleroma.Web.Metadata.Providers.TwitterCard do
- alias Pleroma.User
- alias Pleroma.Web.MediaProxy
- alias Pleroma.Web.Metadata
- alias Pleroma.Web.Metadata.Providers.Provider
- alias Pleroma.Web.Metadata.Utils
- @behaviour Provider
- @media_types ["image", "audio", "video"]
- @impl Provider
- def build_tags(%{activity_id: id, object: object, user: user}) do
- attachments = build_attachments(id, object)
- scrubbed_content = Utils.scrub_html_and_truncate(object)
- [
- title_tag(user),
- {:meta, [name: "twitter:description", content: scrubbed_content], []}
- ] ++
- if attachments == [] or Metadata.activity_nsfw?(object) do
- [
- image_tag(user),
- {:meta, [name: "twitter:card", content: "summary"], []}
- ]
- else
- attachments
- end
- end
- @impl Provider
- def build_tags(%{user: user}) do
- with truncated_bio = Utils.scrub_html_and_truncate(user.bio) do
- [
- title_tag(user),
- {:meta, [name: "twitter:description", content: truncated_bio], []},
- image_tag(user),
- {:meta, [name: "twitter:card", content: "summary"], []}
- ]
- end
- end
- defp title_tag(user) do
- {:meta, [name: "twitter:title", content: Utils.user_name_string(user)], []}
- end
- def image_tag(user) do
- {:meta, [name: "twitter:image", content: MediaProxy.preview_url(User.avatar_url(user))], []}
- end
- defp build_attachments(id, %{data: %{"attachment" => attachments}}) do
- Enum.reduce(attachments, [], fn attachment, acc ->
- rendered_tags =
- Enum.reduce(attachment["url"], [], fn url, acc ->
- case Utils.fetch_media_type(@media_types, url["mediaType"]) do
- "audio" ->
- [
- {:meta, [name: "twitter:card", content: "player"], []},
- {:meta, [name: "twitter:player:width", content: "480"], []},
- {:meta, [name: "twitter:player:height", content: "80"], []},
- {:meta, [name: "twitter:player", content: player_url(id)], []}
- | acc
- ]
- # Not using preview_url for this. It saves bandwidth, but the image dimensions will
- # be wrong. We generate it on the fly and have no way to capture or analyze the
- # image to get the dimensions. This can be an issue for apps/FEs rendering images
- # in timelines too, but you can get clever with the aspect ratio metadata as a
- # workaround.
- "image" ->
- [
- {:meta, [name: "twitter:card", content: "summary_large_image"], []},
- {:meta,
- [
- name: "twitter:image",
- content: MediaProxy.url(url["href"])
- ], []},
- {:meta, [name: "twitter:image:alt", content: truncate(attachment["name"])], []}
- | acc
- ]
- |> maybe_add_dimensions(url)
- "video" ->
- # fallback to old placeholder values
- height = url["height"] || 480
- width = url["width"] || 480
- [
- {:meta, [name: "twitter:card", content: "player"], []},
- {:meta, [name: "twitter:player", content: player_url(id)], []},
- {:meta, [name: "twitter:player:width", content: "#{width}"], []},
- {:meta, [name: "twitter:player:height", content: "#{height}"], []},
- {:meta, [name: "twitter:player:stream", content: MediaProxy.url(url["href"])],
- []},
- {:meta, [name: "twitter:player:stream:content_type", content: url["mediaType"]],
- []}
- | acc
- ]
- _ ->
- acc
- end
- end)
- acc ++ rendered_tags
- end)
- end
- defp build_attachments(_id, _object), do: []
- defp player_url(id) do
- Pleroma.Web.Router.Helpers.o_status_url(Pleroma.Web.Endpoint, :notice_player, id)
- end
- # Videos have problems without dimensions, but we used to not provide WxH for images.
- # A default (read: incorrect) fallback for images is likely to cause rendering bugs.
- defp maybe_add_dimensions(metadata, url) do
- cond do
- !is_nil(url["height"]) && !is_nil(url["width"]) ->
- metadata ++
- [
- {:meta, [name: "twitter:player:width", content: "#{url["width"]}"], []},
- {:meta, [name: "twitter:player:height", content: "#{url["height"]}"], []}
- ]
- true ->
- metadata
- end
- end
- defp truncate(nil), do: ""
- defp truncate(text) do
- # truncate to 420 characters
- # see https://developer.twitter.com/en/docs/twitter-for-websites/cards/overview/markup
- Pleroma.Formatter.truncate(text, 420)
- end
- end