mobilizon/lib/service/rich_media/parsers/oembed_parser.ex

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# Portions of this file are derived from Pleroma:
# Pleroma: A lightweight social networking server
# Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
# SPDX-License-Identifier: AGPL-3.0-only
defmodule Mobilizon.Service.RichMedia.Parsers.OEmbed do
@moduledoc """
Module to parse OEmbed data in HTML pages
"""
alias Mobilizon.Service.Formatter.HTML
require Logger
@http_options [
follow_redirect: true,
ssl: [{:versions, [:"tlsv1.2"]}]
]
@spec parse(String.t(), map()) :: {:ok, map()} | {:error, String.t()}
def parse(html, _data) do
Logger.debug("Using OEmbed parser")
with elements = [_ | _] <- get_discovery_data(html),
{:ok, oembed_url} <- get_oembed_url(elements),
{:ok, oembed_data} <- get_oembed_data(oembed_url),
{:ok, oembed_data} <- filter_oembed_data(oembed_data) do
Logger.debug("Data found with OEmbed parser")
Logger.debug(inspect(oembed_data))
{:ok, oembed_data}
else
_e ->
{:error, "No OEmbed data found"}
end
end
defp get_discovery_data(html) do
with {:ok, document} <- Floki.parse_document(html) do
Floki.find(document, "link[type='application/json+oembed']")
end
end
defp get_oembed_url(nodes) do
{"link", attributes, _children} = nodes |> hd()
{:ok, Enum.into(attributes, %{})["href"]}
end
@oembed_allowed_attributes [
:type,
:version,
:html,
:width,
:height,
:title,
:author_name,
:author_url,
:provider_name,
:provider_url,
:cache_age,
:thumbnail_url,
:thumbnail_width,
:thumbnail_height,
:url
]
defp get_oembed_data(url) do
with {:ok, %{body: json}} <- Tesla.get(url, opts: @http_options),
{:ok, data} <- Jason.decode(json),
data <-
data
|> Map.new(fn {k, v} -> {String.to_existing_atom(k), v} end)
|> Map.take(@oembed_allowed_attributes) do
{:ok, data}
end
end
defp filter_oembed_data(data) do
case Map.get(data, :type) do
nil ->
{:error, "No type declared for OEmbed data"}
"link" ->
data
|> Map.put(:image_remote_url, Map.get(data, :thumbnail_url))
|> (&{:ok, &1}).()
"photo" ->
if Map.get(data, :url, "") == "" do
{:error, "No URL for photo OEmbed data"}
else
data
|> Map.put(:image_remote_url, Map.get(data, :url))
|> Map.put(:width, Map.get(data, :width, 0))
|> Map.put(:height, Map.get(data, :height, 0))
|> (&{:ok, &1}).()
end
"video" ->
{:ok, html} = data |> Map.get(:html, "") |> HTML.filter_tags_for_oembed()
data
|> Map.put(:html, html)
|> Map.put(:width, Map.get(data, :width, 0))
|> Map.put(:height, Map.get(data, :height, 0))
|> Map.put(:image_remote_url, Map.get(data, :thumbnail_url))
|> (&{:ok, &1}).()
"rich" ->
{:error, "OEmbed data has rich type, which we don't support"}
end
end
end