Update

lib/nulla/activitypub.ex

@@ -85,47 +85,58 @@ defmodule Nulla.ActivityPub do
     )
   end
 
-  @spec note(String.t(), Nulla.Models.User.t(), Nulla.Models.Note.t()) :: Jason.OrderedObject.t()
-  def note(domain, user, note) do
+  @spec note(String.t(), Nulla.Models.Note.t()) :: Jason.OrderedObject.t()
+  def note(domain, note) do
+    attachment =
+    case note.media_attachments do
+      [] -> []
+      attachments ->
+        [
+          attachment:
+            Enum.map(attachments, fn att ->
+              Jason.OrderedObject.new(
+                type: "Document",
+                mediaType: att.mime_type,
+                url: "https://#{domain}/files/#{att.file}"
+              )
+            end)
+        ]
+    end
+
     Jason.OrderedObject.new(
       "@context": [
         "https://www.w3.org/ns/activitystreams",
         Jason.OrderedObject.new(sensitive: "as:sensitive")
       ],
-      id: "https://#{domain}/@#{user.username}/#{note.id}",
+      id: "https://#{domain}/@#{note.user.username}/#{note.id}",
       type: "Note",
       summary: nil,
       inReplyTo: nil,
       published: note.inserted_at,
-      url: "https://#{domain}/@#{user.username}/#{note.id}",
-      attributedTo: "https://#{domain}/@#{user.username}",
+      url: "https://#{domain}/@#{note.user.username}/#{note.id}",
+      attributedTo: "https://#{domain}/@#{note.user.username}",
       to: [
         "https://www.w3.org/ns/activitystreams#Public"
       ],
       cc: [
-        "https://#{domain}/@#{user.username}/followers"
+        "https://#{domain}/@#{note.user.username}/followers"
       ],
       sensetive: false,
       content: note.content,
       contentMap: Jason.OrderedObject.new("#{note.language}": note.content),
-      attachment: [
-        Jason.OrderedObject.new(
-          type: "Document",
-          mediaType: "#{note.media_attachment.mime_type}",
-          url: "https://#{domain}/files/#{note.media_attachment.file}"
-        )
-      ]
+      attachment: attachment
     )
   end
 
-  def activity(domain, action) do
+  @spec activity(String.t(), Nulla.Models.Activity.t()) :: Jason.OrderedObject.t()
+  def activity(domain, activity) do
     Jason.OrderedObject.new(
       "@context": "https://www.w3.org/ns/activitystreams",
-      id: "https://#{domain}/activities/#{action.id}",
-      type: action.type,
-      actor: action.actor,
-      object: action.object,
-      to: action.to
+      id: "https://#{domain}/activities/#{activity.id}",
+      type: activity.type,
+      actor: activity.actor,
+      object: activity.object,
+      to: activity.to
     )
   end
 end

lib/nulla/models/note.ex

@@ -29,5 +29,7 @@ defmodule Nulla.Models.Note do
     |> validate_required([:content, :visibility, :sensitive, :language, :in_reply_to, :user_id])
   end
 
+  def get_note!(id), do: Repo.get!(Note, id)
+
   def get_all_notes!(user_id), do: Repo.all(from n in Note, where: n.user_id == ^user_id)
 end

lib/nulla_web/controllers/note_controller.ex

@@ -1,8 +1,9 @@
 defmodule NullaWeb.NoteController do
   use NullaWeb, :controller
-
-  alias Nulla.Notes
+  alias Nulla.Repo
   alias Nulla.Models.Note
+  alias Nulla.Models.InstanceSettings
+  alias Nulla.ActivityPub
 
   def index(conn, _params) do
     notes = Notes.list_notes()
@@ -26,11 +27,33 @@ defmodule NullaWeb.NoteController do
     end
   end
 
-  def show(conn, %{"id" => id}) do
-    note = Notes.get_note!(id)
-    render(conn, :show, note: note)
+  def show(conn, %{"username" => username, "note_id" => note_id}) do
+    accept = List.first(get_req_header(conn, "accept"))
+    instance_settings = InstanceSettings.get_instance_settings!()
+    domain = instance_settings.domain
+    note = Note.get_note!(note_id) |> Repo.preload([:user, :media_attachments])
+
+    if username != note.user.username do
+      conn
+      |> put_status(:not_found)
+      |> json(%{error: "Note not found"})
+      |> halt()
+    end
+
+    if accept in ["application/activity+json", "application/ld+json"] do
+      conn
+      |> put_resp_content_type("application/activity+json")
+      |> json(ActivityPub.note(domain, note))
+    else
+      render(conn, :show, domain: domain, note: note, layout: false)
+    end
   end
 
+  #def show(conn, %{"id" => id}) do
+  #  note = Notes.get_note!(id)
+  #  render(conn, :show, note: note)
+  #end
+
   def edit(conn, %{"id" => id}) do
     note = Notes.get_note!(id)
     changeset = Notes.change_note(note)

lib/nulla_web/router.ex

@@ -22,7 +22,7 @@ defmodule NullaWeb.Router do
     pipe_through :browser
 
     get "/@:username", UserController, :show
-    resources "/users", UserController
+    get "/@:username/:note_id", NoteController, :show
   end
 
   # Other scopes may use custom stacks.