Add OEmbed parser

lib/pleroma/web/rich_media/parser.ex

@@ -1,5 +1,9 @@
 defmodule Pleroma.Web.RichMedia.Parser do
-  @parsers [Pleroma.Web.RichMedia.Parsers.OGP, Pleroma.Web.RichMedia.Parsers.TwitterCard]
+  @parsers [
+    Pleroma.Web.RichMedia.Parsers.OGP,
+    Pleroma.Web.RichMedia.Parsers.TwitterCard,
+    Pleroma.Web.RichMedia.Parsers.OEmbed
+  ]
 
   if Mix.env() == :test do
     def parse(url), do: parse_url(url)

lib/pleroma/web/rich_media/parsers/oembed_parser.ex

@@ -0,0 +1,27 @@
+defmodule Pleroma.Web.RichMedia.Parsers.OEmbed do
+  def parse(html, _data) do
+    with elements = [_ | _] <- get_discovery_data(html),
+         {:ok, oembed_url} <- get_oembed_url(elements),
+         {:ok, oembed_data} <- get_oembed_data(oembed_url) do
+      {:ok, oembed_data}
+    else
+      _e -> {:error, "No OEmbed data found"}
+    end
+  end
+
+  defp get_discovery_data(html) do
+    html |> Floki.find("link[type='application/json+oembed']")
+  end
+
+  defp get_oembed_url(nodes) do
+    {"link", attributes, _children} = nodes |> hd()
+
+    {:ok, Enum.into(attributes, %{})["href"]}
+  end
+
+  defp get_oembed_data(url) do
+    {:ok, %Tesla.Env{body: json}} = Pleroma.HTTP.get(url)
+
+    {:ok, Poison.decode!(json)}
+  end
+end