neiam /gitgud

defmodule GitGudWeb.WellKnownController do
  @moduledoc """
  Standard `.well-known` endpoints used by AP-aware clients to discover
  our instance + resolve `acct:` URIs.

    * `/.well-known/webfinger?resource=acct:<handle>@<host>`
    * `/.well-known/nodeinfo`
    * `/nodeinfo/2.1`
  """

  use GitGudWeb, :controller

  alias GitGud.Federation

  def webfinger(conn, %{"resource" => "acct:" <> account}) do
    case parse_account(account) do
      {:ok, handle, host} ->
        if same_host?(host) do
          render_webfinger(conn, handle)
        else
          send_resp(conn, 404, "")
        end

      :error ->
        send_resp(conn, 400, "")
    end
  end

  def webfinger(conn, _params), do: send_resp(conn, 400, "")

  defp parse_account(account) do
    case String.split(account, "@", parts: 2) do
      [handle, host] when handle != "" and host != "" -> {:ok, handle, host}
      _ -> :error
    end
  end

  defp same_host?(host) do
    URI.parse(Federation.base_url()).host == host
  end

  defp render_webfinger(conn, handle) do
    case Federation.find_local_actor_by_handle(handle) do
      nil ->
        send_resp(conn, 404, "")

      actor ->
        body =
          %{
            "subject" => "acct:#{handle}@#{URI.parse(Federation.base_url()).host}",
            "aliases" => [actor.actor_url],
            "links" => [
              %{
                "rel" => "self",
                "type" => "application/activity+json",
                "href" => actor.actor_url
              },
              %{
                "rel" => "http://webfinger.net/rel/profile-page",
                "type" => "text/html",
                "href" => actor.actor_url
              }
            ]
          }
          |> Jason.encode!()

        conn
        |> put_resp_content_type("application/jrd+json", nil)
        |> send_resp(200, body)
    end
  end

  def nodeinfo_index(conn, _params) do
    body =
      %{
        "links" => [
          %{
            "rel" => "http://nodeinfo.diaspora.software/ns/schema/2.1",
            "href" => Federation.base_url() <> "/nodeinfo/2.1"
          }
        ]
      }
      |> Jason.encode!()

    conn
    |> put_resp_content_type("application/json", nil)
    |> send_resp(200, body)
  end

  def nodeinfo_2_1(conn, _params) do
    body =
      %{
        "version" => "2.1",
        "software" => %{
          "name" => "gitgud",
          "version" => Application.spec(:git_gud, :vsn) |> to_string(),
          "repository" => "https://github.com/anthropics/gitgud"
        },
        "protocols" => ["activitypub"],
        "services" => %{"inbound" => [], "outbound" => []},
        "openRegistrations" => false,
        "usage" => %{
          "users" => %{"total" => 0},
          "localPosts" => 0
        },
        "metadata" => %{
          "nodeName" => "GitGud",
          "features" => ["forgefed"]
        }
      }
      |> Jason.encode!()

    conn
    |> put_resp_content_type("application/json", nil)
    |> send_resp(200, body)
  end
end