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