transmogrifier.ex: rework fix_attachment for better IR

lib/pleroma/web/activity_pub/transmogrifier.ex

@@ -202,6 +202,51 @@ def fix_context(object) do
     |> Map.put("conversation", context)
   end
 
+  defp add_if_present(map, _key, nil), do: map
+
+  defp add_if_present(map, key, value) do
+    Map.put(map, key, value)
+  end
+
+  def fix_attachments(%{"attachment" => attachment} = object) when is_list(attachment) do
+    attachments =
+      Enum.map(attachment, fn data ->
+        url =
+          cond do
+            is_list(data["url"]) -> List.first(data["url"])
+            is_map(data["url"]) -> data["url"]
+            true -> nil
+          end
+
+        media_type =
+          cond do
+            is_map(url) && is_binary(url["mediaType"]) -> url["mediaType"]
+            is_binary(data["mediaType"]) -> data["mediaType"]
+            is_binary(data["mimeType"]) -> data["mimeType"]
+            true -> nil
+          end
+
+        href =
+          cond do
+            is_map(url) && is_binary(url["href"]) -> url["href"]
+            is_binary(data["url"]) -> data["url"]
+            is_binary(data["href"]) -> data["href"]
+          end
+
+        attachment_url =
+          %{"href" => href}
+          |> add_if_present("mediaType", media_type)
+          |> add_if_present("type", Map.get(url || %{}, "type"))
+
+        %{"url" => [attachment_url]}
+        |> add_if_present("mediaType", media_type)
+        |> add_if_present("type", data["type"])
+        |> add_if_present("name", data["name"])
+      end)
+
+    Map.put(object, "attachment", attachments)
+  end
+
   def fix_attachments(%{"attachment" => attachment} = object) when is_map(attachment) do
     object
     |> Map.put("attachment", [attachment])

test/web/activity_pub/transmogrifier_test.exs

@@ -1228,19 +1228,13 @@ test "it remaps video URLs as attachments if necessary" do
       attachment = %{
         "type" => "Link",
         "mediaType" => "video/mp4",
-        "href" =>
-          "https://peertube.moe/static/webseed/df5f464b-be8d-46fb-ad81-2d4c2d1630e3-480.mp4",
-        "mimeType" => "video/mp4",
-        "size" => 5_015_880,
         "url" => [
           %{
             "href" =>
               "https://peertube.moe/static/webseed/df5f464b-be8d-46fb-ad81-2d4c2d1630e3-480.mp4",
-            "mediaType" => "video/mp4",
+            "mediaType" => "video/mp4"
-            "type" => "Link"
           }
-        ],
+        ]
-        "width" => 480
       }
 
       assert object.data["url"] ==
@@ -2067,11 +2061,7 @@ test "returns modified object when attachment is map" do
                  %{
                    "mediaType" => "video/mp4",
                    "url" => [
-                     %{
+                     %{"href" => "https://peertube.moe/stat-480.mp4", "mediaType" => "video/mp4"}
-                       "href" => "https://peertube.moe/stat-480.mp4",
-                       "mediaType" => "video/mp4",
-                       "type" => "Link"
-                     }
                    ]
                  }
                ]
@@ -2089,23 +2079,13 @@ test "returns modified object when attachment is list" do
                  %{
                    "mediaType" => "video/mp4",
                    "url" => [
-                     %{
+                     %{"href" => "https://pe.er/stat-480.mp4", "mediaType" => "video/mp4"}
-                       "href" => "https://pe.er/stat-480.mp4",
-                       "mediaType" => "video/mp4",
-                       "type" => "Link"
-                     }
                    ]
                  },
                  %{
-                   "href" => "https://pe.er/stat-480.mp4",
                    "mediaType" => "video/mp4",
-                   "mimeType" => "video/mp4",
                    "url" => [
-                     %{
+                     %{"href" => "https://pe.er/stat-480.mp4", "mediaType" => "video/mp4"}
-                       "href" => "https://pe.er/stat-480.mp4",
-                       "mediaType" => "video/mp4",
-                       "type" => "Link"
-                     }
                    ]
                  }
                ]