Refactor Mobilizon.Federation.ActivityPub and add typespecs

Signed-off-by: Thomas Citharel <tcit@tcit.fr>

lib/web/auth/error_handler.ex

@@ -5,6 +5,7 @@ defmodule Mobilizon.Web.Auth.ErrorHandler do
   import Plug.Conn
 
   # sobelow_skip ["XSS.SendResp"]
+  @spec auth_error(Plug.Conn.t(), any(), any()) :: Plug.Conn.t()
   def auth_error(conn, {type, _reason}, _opts) do
     body = Jason.encode!(%{message: to_string(type)})
     send_resp(conn, 401, body)

lib/web/auth/guardian.ex

@@ -15,6 +15,7 @@ defmodule Mobilizon.Web.Auth.Guardian do
 
   require Logger
 
+  @spec subject_for_token(any(), any()) :: {:ok, String.t()} | {:error, :unknown_resource}
   def subject_for_token(%User{} = user, _claims) do
     {:ok, "User:" <> to_string(user.id)}
   end
@@ -45,30 +46,35 @@ defmodule Mobilizon.Web.Auth.Guardian do
     {:error, :no_claims}
   end
 
+  @spec after_encode_and_sign(any(), any(), any(), any()) :: {:ok, String.t()}
   def after_encode_and_sign(resource, claims, token, _options) do
     with {:ok, _} <- Guardian.DB.after_encode_and_sign(resource, claims["typ"], claims, token) do
       {:ok, token}
     end
   end
 
+  @spec on_verify(any(), any(), any()) :: {:ok, any()}
   def on_verify(claims, token, _options) do
     with {:ok, _} <- Guardian.DB.on_verify(claims, token) do
       {:ok, claims}
     end
   end
 
+  @spec on_revoke(any(), any(), any()) :: {:ok, any()}
   def on_revoke(claims, token, _options) do
     with {:ok, _} <- Guardian.DB.on_revoke(claims, token) do
       {:ok, claims}
     end
   end
 
+  @spec on_refresh({any(), any()}, {any(), any()}, any()) :: {:ok, {any(), any()}, {any(), any()}}
   def on_refresh({old_token, old_claims}, {new_token, new_claims}, _options) do
     with {:ok, _, _} <- Guardian.DB.on_refresh({old_token, old_claims}, {new_token, new_claims}) do
       {:ok, {old_token, old_claims}, {new_token, new_claims}}
     end
   end
 
+  @spec on_exchange(any(), any(), any()) :: {:ok, {any(), any()}, {any(), any()}}
   def on_exchange(old_stuff, new_stuff, options), do: on_refresh(old_stuff, new_stuff, options)
 
   #  def build_claims(claims, _resource, opts) do