Update

lib/nulla_web/components/templates/note/show.html.heex

@@ -15,6 +15,7 @@
     </div>
   </div>
   <div class="relative border border-gray-300 shadow-md mt-5 rounded-t-xl overflow-hidden">
+    {@note.content}
   </div>
   <div class="flex flex-col items-center mt-5 gap-5">
     <div class="text-sm rounded-xl border border-gray-300 p-4 w-[90%] h-[300px]"></div>

lib/nulla_web/controllers/note_controller.ex

@@ -5,22 +5,40 @@ defmodule NullaWeb.NoteController do
   alias Nulla.Models.Note
 
   def show(conn, %{"username" => username, "id" => id}) do
-    accept = List.first(get_req_header(conn, "accept"))
-    note = Note.get_note(id) |> Repo.preload([:actor, :media_attachments])
+    case Integer.parse(id) do
+      {int_id, ""} ->
+        note = Note.get_note(int_id) |> Repo.preload([:actor, :media_attachments])
 
-    if username != note.actor.preferredUsername do
-      conn
-      |> put_status(:not_found)
-      |> json(%{error: "Not Found"})
-      |> halt()
-    end
+        cond do
+          is_nil(note) ->
+            conn
+            |> put_status(:not_found)
+            |> json(%{error: "Not Found"})
+            |> halt()
 
-    if accept in ["application/activity+json", "application/ld+json"] do
-      conn
-      |> put_resp_content_type("application/activity+json")
-      |> json(ActivityPub.note(note))
-    else
-      render(conn, :show, note: note, layout: false)
+          username != note.actor.preferredUsername ->
+            conn
+            |> put_status(:not_found)
+            |> json(%{error: "Not Found"})
+            |> halt()
+
+          true ->
+            accept = List.first(get_req_header(conn, "accept"))
+
+            if accept in ["application/activity+json", "application/ld+json"] do
+              conn
+              |> put_resp_content_type("application/activity+json")
+              |> json(ActivityPub.note(note))
+            else
+              render(conn, :show, note: note, layout: false)
+            end
+        end
+
+      _ ->
+        conn
+        |> put_status(:not_found)
+        |> json(%{error: "Not Found"})
+        |> halt()
     end
   end
 end

test/nulla_web/controllers/note_controller_test.exs

@@ -71,5 +71,59 @@ defmodule NullaWeb.NoteControllerTest do
       assert is_map(response["contentMap"])
       assert is_list(response["attachment"])
     end
+
+    test "renders HTML if Accept header is regular", %{conn: conn} do
+      {publicKeyPem, _privateKeyPem} = KeyGen.gen()
+
+      {:ok, actor} =
+        Actor.create_actor(%{
+          domain: "localhost",
+          ap_id: "http://localhost/users/test",
+          type: "Person",
+          following: "http://localhost/users/test/following",
+          followers: "http://localhost/users/test/followers",
+          inbox: "http://localhost/users/test/inbox",
+          outbox: "http://localhost/users/test/outbox",
+          featured: "http://localhost/users/test/collections/featured",
+          featuredTags: "http://localhost/users/test/collections/tags",
+          preferredUsername: "test",
+          name: "Test",
+          summary: "Test User",
+          url: "http://localhost/@test",
+          manuallyApprovesFollowers: false,
+          discoverable: true,
+          indexable: true,
+          published: DateTime.utc_now(),
+          memorial: false,
+          publicKey:
+            Jason.OrderedObject.new(
+              id: "http://localhost/users/test#main-key",
+              owner: "http://localhost/users/test",
+              publicKeyPem: publicKeyPem
+            ),
+          endpoints: Jason.OrderedObject.new(sharedInbox: "http://localhost/inbox")
+        })
+
+      note_id = Snowflake.next_id()
+
+      {:ok, note} =
+        Note.create_note(%{
+          id: note_id,
+          url: "#{actor.url}/#{note_id}",
+          content: "Hello World from Nulla!",
+          language: "en",
+          actor_id: actor.id
+        })
+
+      conn = get(conn, ~p"/users/test/notes/#{note.id}")
+
+      assert html_response(conn, 200) =~ note.content
+    end
+
+    test "returns 404 if note not found", %{conn: conn} do
+      conn = get(conn, ~p"/users/test/notes/nonexistent")
+
+      assert json_response(conn, 404)["error"] == "Not Found"
+    end
   end
 end