148 lines
		
	
	
	
		
			4.9 KiB
		
	
	
	
		
			Elixir
		
	
	
	
	
	
			
		
		
	
	
			148 lines
		
	
	
	
		
			4.9 KiB
		
	
	
	
		
			Elixir
		
	
	
	
	
	
# Pleroma: A lightweight social networking server
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# Copyright © 2017-2021 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.OpenGraph 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(%{
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        object: object,
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        url: url,
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        user: user
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      }) do
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    attachments = build_attachments(object)
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    scrubbed_content = Utils.scrub_html_and_truncate(object)
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    [
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      {:meta,
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       [
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         property: "og:title",
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         content: Utils.user_name_string(user)
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       ], []},
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      {:meta, [property: "og:url", content: url], []},
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      {:meta,
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       [
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         property: "og:description",
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         content: scrubbed_content
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       ], []},
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      {:meta, [property: "og:type", content: "article"], []}
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    ] ++
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      if attachments == [] or Metadata.activity_nsfw?(object) do
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        [
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          {:meta, [property: "og:image", content: MediaProxy.preview_url(User.avatar_url(user))],
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           []},
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          {:meta, [property: "og:image:width", content: 150], []},
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          {:meta, [property: "og:image:height", content: 150], []}
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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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        {:meta,
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         [
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           property: "og:title",
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           content: Utils.user_name_string(user)
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         ], []},
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        {:meta, [property: "og:url", content: user.uri || user.ap_id], []},
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        {:meta, [property: "og:description", content: truncated_bio], []},
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        {:meta, [property: "og:type", content: "article"], []},
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        {:meta, [property: "og:image", content: MediaProxy.preview_url(User.avatar_url(user))],
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         []},
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        {:meta, [property: "og:image:width", content: 150], []},
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        {:meta, [property: "og:image:height", content: 150], []}
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      ]
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    end
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  end
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  defp build_attachments(%{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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          # TODO: Whatsapp only wants JPEG or PNGs. It seems that if we add a second og:image
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          # object when a Video or GIF is attached it will display that in Whatsapp Rich Preview.
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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, [property: "og:audio", content: MediaProxy.url(url["href"])], []}
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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, [property: "og:image", content: MediaProxy.url(url["href"])], []},
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                {:meta, [property: "og:image:alt", content: 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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              [
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                {:meta, [property: "og:video", content: MediaProxy.url(url["href"])], []}
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                | acc
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              ]
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              |> maybe_add_dimensions(url)
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              |> maybe_add_video_thumbnail(url)
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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(_), do: []
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  # We can use url["mediaType"] to dynamically fill the metadata
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  defp maybe_add_dimensions(metadata, url) do
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    type = url["mediaType"] |> String.split("/") |> List.first()
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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, [property: "og:#{type}:width", content: "#{url["width"]}"], []},
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            {:meta, [property: "og:#{type}: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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  # Media Preview Proxy makes thumbnails of videos without resizing, so we can trust the
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  # width and height of the source video.
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  defp maybe_add_video_thumbnail(metadata, url) do
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    cond do
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      Pleroma.Config.get([:media_preview_proxy, :enabled], false) ->
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        metadata ++
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          [
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            {:meta, [property: "og:image:width", content: "#{url["width"]}"], []},
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            {:meta, [property: "og:image:height", content: "#{url["height"]}"], []},
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            {:meta, [property: "og:image", content: MediaProxy.preview_url(url["href"])], []}
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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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end
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