Add REST API for creating an account (#9572)

* Add REST API for creating an account

The method is available to apps with a token obtained via the client
credentials grant. It creates a user and account records, as well as
an access token for the app that initiated the request. The user is
unconfirmed, and an e-mail is sent as usual.

The method returns the access token, which the app should save for
later. The REST API is not available to users with unconfirmed
accounts, so the app must be smart to wait for the user to click a
link in their e-mail inbox.

The method is rate-limited by IP to 5 requests per 30 minutes.

* Redirect users back to app from confirmation if they were created with an app

* Add tests

* Return 403 on the method if registrations are not open

* Require agreement param to be true in the API when creating an account

app/controllers/auth/confirmations_controller.rb

@@ -6,9 +6,9 @@ class Auth::ConfirmationsController < Devise::ConfirmationsController
   before_action :set_body_classes
   before_action :set_user, only: [:finish_signup]
 
-  # GET/PATCH /users/:id/finish_signup
   def finish_signup
     return unless request.patch? && params[:user]
+
     if @user.update(user_params)
       @user.skip_reconfirmation!
       bypass_sign_in(@user)
@@ -31,4 +31,12 @@ class Auth::ConfirmationsController < Devise::ConfirmationsController
   def user_params
     params.require(:user).permit(:email)
   end
+
+  def after_confirmation_path_for(_resource_name, user)
+    if user.created_by_application && truthy_param?(:redirect_to_app)
+      user.created_by_application.redirect_uri
+    else
+      super
+    end
+  end
 end

app/controllers/auth/registrations_controller.rb

@@ -26,6 +26,7 @@ class Auth::RegistrationsController < Devise::RegistrationsController
 
     resource.locale      = I18n.locale
     resource.invite_code = params[:invite_code] if resource.invite_code.blank?
+    resource.agreement   = true
 
     resource.build_account if resource.account.nil?
   end