nulla/lib/nulla_web/controllers/activitypub/inbox_controller.ex

defmodule NullaWeb.ActivityPub.InboxController do
  use NullaWeb, :controller
  alias Nulla.Snowflake
  alias Nulla.HTTPSignature
  alias Nulla.Sender
  alias Nulla.Utils
  alias Nulla.Actors
  alias Nulla.Relations
  alias Nulla.Activities

  def inbox(conn, %{
        "id" => _create_id,
        "type" => "Create",
        "actor" => _actor_uri,
        "object" => _target_uri
      }) do
    send_resp(conn, 200, "")
  end

  def inbox(conn, %{
        "id" => _read_id,
        "type" => "Read",
        "actor" => _actor_uri,
        "object" => _target_uri
      }) do
    send_resp(conn, 200, "")
  end

  def inbox(conn, %{
        "id" => _update_id,
        "type" => "Update",
        "actor" => _actor_uri,
        "object" => _target_uri
      }) do
    send_resp(conn, 200, "")
  end

  def inbox(conn, %{
        "id" => _delete_id,
        "type" => "Delete",
        "actor" => _actor_uri,
        "object" => _target_uri
      }) do
    send_resp(conn, 200, "")
  end

  def inbox(conn, %{
        "id" => _add_id,
        "type" => "Add",
        "actor" => _actor_uri,
        "object" => _target_uri
      }) do
    send_resp(conn, 200, "")
  end

  def inbox(conn, %{
        "id" => _view_id,
        "type" => "View",
        "actor" => _actor_uri,
        "object" => _target_uri
      }) do
    send_resp(conn, 200, "")
  end

  def inbox(conn, %{
        "id" => _move_id,
        "type" => "Move",
        "actor" => _actor_uri,
        "object" => _target_uri
      }) do
    send_resp(conn, 200, "")
  end

  def inbox(conn, %{
        "id" => _undo_id,
        "type" => "Undo",
        "actor" => _actor_uri,
        "object" => _target_uri
      }) do
    send_resp(conn, 200, "")
  end

  def inbox(conn, %{
        "id" => follow_id,
        "type" => "Follow",
        "actor" => actor_uri,
        "object" => target_uri
      }) do
    accept_id = Snowflake.next_id()

    with local_actor <- Actors.get_actor_by(ap_id: target_uri),
         {:ok, remote_actor_json} <- Utils.fetch_remote_actor(actor_uri),
         :ok <- HTTPSignature.verify(conn, remote_actor_json["publicKey"]["publicKeyPem"]) do
      ap_id = remote_actor_json["id"]
      username = remote_actor_json["preferredUsername"]
      domain = URI.parse(remote_actor_json["id"]).host

      remote_actor =
        case Actors.get_actor_by(ap_id: ap_id) do
          nil ->
            params =
              remote_actor_json
              |> Map.put("ap_id", ap_id)
              |> Map.delete("id")
              |> Map.put("acct", "#{username}@#{domain}")

            case Actors.create_actor(params) do
              {:ok, actor} -> actor
              {:error, error} -> {:error, error}
            end

          actor ->
            actor
        end

      domain = NullaWeb.Endpoint.host()

      with {:ok, follow_activity} <-
             Activities.create_activity(%{
               ap_id: follow_id,
               type: "Follow",
               actor: remote_actor.ap_id,
               object: target_uri
             }),
           {:ok, accept_activity} <-
             Activities.create_activity(%{
               id: accept_id,
               ap_id: "https://#{domain}/activities/accept/#{accept_id}",
               type: "Accept",
               actor: local_actor.ap_id,
               object: Jason.encode!(follow_activity)
             }) do
        {:ok, _relation} =
          case Relations.get_relation_by(%{
                 local_actor_id: local_actor.id,
                 remote_actor_id: remote_actor.id
               }) do
            nil ->
              case Relations.create_relation(%{
                     local_actor_id: local_actor.id,
                     remote_actor_id: remote_actor.id,
                     followed_by: true
                   }) do
                {:ok, relation} -> relation
                {:error, changeset} -> {:error, {:relation_creation_failed, changeset}}
              end

            relation ->
              {:ok, Relations.update_relation(relation, %{followed_by: true})}
          end

        Sender.send_activity(
          :post,
          remote_actor.inbox,
          accept_activity,
          local_actor.publicKey["id"],
          local_actor.privateKeyPem
        )

        send_resp(conn, 200, "")
      else
        error ->
          json(conn, %{"error" => "Failed to process Follow: #{error}"})
      end
    else
      error ->
        json(conn, %{"error" => "Failed to process Follow: #{error}"})
    end
  end

  def inbox(conn, %{
        "id" => _accept_id,
        "type" => "Accept",
        "actor" => _actor_uri,
        "object" => _target_uri
      }) do
    send_resp(conn, 200, "")
  end

  def inbox(conn, %{
        "id" => _reject_id,
        "type" => "Reject",
        "actor" => _actor_uri,
        "object" => _target_uri
      }) do
    send_resp(conn, 200, "")
  end

  def inbox(conn, %{
        "id" => _block_id,
        "type" => "Block",
        "actor" => _actor_uri,
        "object" => _target_uri
      }) do
    send_resp(conn, 200, "")
  end

  def inbox(conn, %{
        "id" => _join_id,
        "type" => "Join",
        "actor" => _actor_uri,
        "object" => _target_uri
      }) do
    send_resp(conn, 200, "")
  end

  def inbox(conn, %{
        "id" => _leave_id,
        "type" => "Leave",
        "actor" => _actor_uri,
        "object" => _target_uri
      }) do
    send_resp(conn, 200, "")
  end

  def inbox(conn, %{
        "id" => _like_id,
        "type" => "Like",
        "actor" => _actor_uri,
        "object" => _target_uri
      }) do
    send_resp(conn, 200, "")
  end

  def inbox(conn, %{
        "id" => _dislike_id,
        "type" => "Dislike",
        "actor" => _actor_uri,
        "object" => _target_uri
      }) do
    send_resp(conn, 200, "")
  end

  def inbox(conn, %{
        "id" => _announce_id,
        "type" => "Announce",
        "actor" => _actor_uri,
        "object" => _target_uri
      }) do
    send_resp(conn, 200, "")
  end

  def inbox(conn, %{
        "id" => _question_id,
        "type" => "Question",
        "actor" => _actor_uri,
        "object" => _target_uri
      }) do
    send_resp(conn, 200, "")
  end

  def inbox(conn, _params) do
    send_resp(conn, 400, "")
  end
end