Parse object link as quoteUrl

lib/pleroma/constants.ex

@@ -83,4 +83,11 @@ defmodule Pleroma.Constants do
   )
 
   const(upload_object_types, do: ["Document", "Image"])
+
+  const(activity_json_mime_types,
+    do: [
+      "application/ld+json; profile=\"https://www.w3.org/ns/activitystreams\"",
+      "application/activity+json"
+    ]
+  )
 end

lib/pleroma/web/activity_pub/object_validators/audio_image_video_validator.ex

@@ -99,6 +99,7 @@ defp fix(data) do
     data
     |> CommonFixes.fix_actor()
     |> CommonFixes.fix_object_defaults()
+    |> CommonFixes.fix_quote_url()
     |> Transmogrifier.fix_emoji()
     |> fix_url()
     |> fix_content()

lib/pleroma/web/activity_pub/object_validators/common_fixes.ex

@@ -10,6 +10,8 @@ defmodule Pleroma.Web.ActivityPub.ObjectValidators.CommonFixes do
   alias Pleroma.Web.ActivityPub.Transmogrifier
   alias Pleroma.Web.ActivityPub.Utils
 
+  require Pleroma.Constants
+
   def cast_and_filter_recipients(message, field, follower_collection, field_fallback \\ []) do
     {:ok, data} = ObjectValidators.Recipients.cast(message[field] || field_fallback)
 
@@ -96,5 +98,30 @@ def fix_quote_url(%{"_misskey_quote" => quote_url} = data) do
     Map.put(data, "quoteUrl", quote_url)
   end
 
-  def fix_quote_url(data), do: data
+  def fix_quote_url(%{"tag" => [_ | _] = tags} = data) do
+    tag = Enum.find(tags, &is_object_link_tag/1)
+
+    if not is_nil(tag) do
+      data
+      |> Map.put("quoteUrl", tag["href"])
+    else
+      data
+    end
+  end
+
+  def fix_quote_url(data), do: data
+
+  # https://codeberg.org/fediverse/fep/src/branch/main/fep/e232/fep-e232.md
+  defp is_object_link_tag(
+         %{
+           "type" => "Link",
+           "mediaType" => media_type,
+           "href" => href
+         } = tag
+       )
+       when media_type in Pleroma.Constants.activity_json_mime_types() and is_binary(href) do
+    true
+  end
+
+  defp is_object_link_tag(_), do: false
 end

lib/pleroma/web/activity_pub/object_validators/question_validator.ex

@@ -62,6 +62,7 @@ defp fix(data) do
     data
     |> CommonFixes.fix_actor()
     |> CommonFixes.fix_object_defaults()
+    |> CommonFixes.fix_quote_url()
     |> Transmogrifier.fix_emoji()
     |> fix_closed()
   end

test/fixtures/quote_post/fep-e232-tag-example.json

@@ -0,0 +1,17 @@
+{
+  "@context": "https://www.w3.org/ns/activitystreams",
+  "type": "Note",
+  "content": "This is a quote:<br>RE: https://server.example/objects/123",
+  "tag": [
+    {
+      "type": "Link",
+      "mediaType": "application/ld+json; profile=\"https://www.w3.org/ns/activitystreams\"",
+      "href": "https://server.example/objects/123",
+      "name": "RE: https://server.example/objects/123"
+    }
+  ],
+  "id": "https://server.example/objects/1",
+  "to": "https://server.example/users/1",
+  "attributedTo": "https://server.example/users/1",
+  "actor": "https://server.example/users/1"
+}

test/pleroma/web/activity_pub/object_validators/article_note_page_validator_test.exs

@@ -146,4 +146,16 @@ test "Misskey quote post" do
     assert cng.valid?
     assert cng.changes.quoteUrl == "https://misskey.io/notes/8vs6wxufd0"
   end
+
+  test "Parse tag as quote" do
+    # https://codeberg.org/fediverse/fep/src/branch/main/fep/e232/fep-e232.md
+
+    insert(:user, ap_id: "https://server.example/users/1")
+
+    data = File.read!("test/fixtures/quote_post/fep-e232-tag-example.json") |> Jason.decode!()
+    cng = ArticleNotePageValidator.cast_and_validate(data)
+
+    assert cng.valid?
+    assert cng.changes.quoteUrl == "https://server.example/objects/123"
+  end
 end