Pleroma/lib/pleroma/web/metadata/opengraph.ex

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# Pleroma: A lightweight social networking server
# Copyright © 2017-2019 Pleroma Authors <https://pleroma.social/>
# SPDX-License-Identifier: AGPL-3.0-only
defmodule Pleroma.Web.Metadata.Providers.OpenGraph do
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alias Pleroma.HTML
alias Pleroma.Formatter
alias Pleroma.User
alias Pleroma.Web.Metadata
alias Pleroma.Web.MediaProxy
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alias Pleroma.Web.Metadata.Providers.Provider
@behaviour Provider
@impl Provider
def build_tags(%{
object: object,
url: url,
user: user
}) do
attachments = build_attachments(object)
scrubbed_content = scrub_html_and_truncate(object)
# Zero width space
content =
if scrubbed_content != "" and scrubbed_content != "\u200B" do
": “" <> scrubbed_content <> ""
else
""
end
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# Most previews only show og:title which is inconvenient. Instagram
# hacks this by putting the description in the title and making the
# description longer prefixed by how many likes and shares the post
# has. Here we use the descriptive nickname in the title, and expand
# the full account & nickname in the description. We also use the cute^Wevil
# smart quotes around the status text like Instagram, too.
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[
{:meta,
[
property: "og:title",
content: "#{user.name}" <> content
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], []},
{:meta, [property: "og:url", content: url], []},
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{:meta,
[
property: "og:description",
content: "#{user_name_string(user)}" <> content
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], []},
{:meta, [property: "og:type", content: "website"], []}
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] ++
if attachments == [] or Metadata.activity_nsfw?(object) do
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[
{:meta, [property: "og:image", content: attachment_url(User.avatar_url(user))], []},
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{:meta, [property: "og:image:width", content: 150], []},
{:meta, [property: "og:image:height", content: 150], []}
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]
else
attachments
end
end
@impl Provider
def build_tags(%{user: user}) do
with truncated_bio = scrub_html_and_truncate(user.bio || "") do
[
{:meta,
[
property: "og:title",
content: user_name_string(user)
], []},
{:meta, [property: "og:url", content: User.profile_url(user)], []},
{:meta, [property: "og:description", content: truncated_bio], []},
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{:meta, [property: "og:type", content: "website"], []},
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{:meta, [property: "og:image", content: attachment_url(User.avatar_url(user))], []},
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{:meta, [property: "og:image:width", content: 150], []},
{:meta, [property: "og:image:height", content: 150], []}
]
end
end
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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media_type =
Enum.find(["image", "audio", "video"], fn media_type ->
String.starts_with?(url["mediaType"], media_type)
end)
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# TODO: Add additional properties to objects when we have the data available.
# Also, Whatsapp only wants JPEG or PNGs. It seems that if we add a second og:image
# object when a Video or GIF is attached it will display that in the Whatsapp Rich Preview.
case media_type do
"audio" ->
[
{:meta, [property: "og:" <> media_type, content: attachment_url(url["href"])], []}
| acc
]
"image" ->
[
{:meta, [property: "og:" <> media_type, content: attachment_url(url["href"])],
[]},
{:meta, [property: "og:image:width", content: 150], []},
{:meta, [property: "og:image:height", content: 150], []}
| acc
]
"video" ->
[
{:meta, [property: "og:" <> media_type, content: attachment_url(url["href"])], []}
| acc
]
_ ->
acc
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end
end)
acc ++ rendered_tags
end)
end
defp scrub_html_and_truncate(%{data: %{"content" => content}} = object) do
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content
# html content comes from DB already encoded, decode first and scrub after
|> HtmlEntities.decode()
|> String.replace(~r/<br\s?\/?>/, " ")
|> HTML.get_cached_stripped_html_for_object(object, __MODULE__)
|> Formatter.demojify()
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|> Formatter.truncate()
end
defp scrub_html_and_truncate(content) when is_binary(content) do
content
# html content comes from DB already encoded, decode first and scrub after
|> HtmlEntities.decode()
|> String.replace(~r/<br\s?\/?>/, " ")
|> HTML.strip_tags()
|> Formatter.demojify()
|> Formatter.truncate()
end
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defp attachment_url(url) do
MediaProxy.url(url)
end
defp user_name_string(user) do
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"#{user.name} " <>
if user.local do
"(@#{user.nickname}@#{Pleroma.Web.Endpoint.host()})"
else
"(@#{user.nickname})"
end
end
end