Add domain index action (without pagination yet)

app/controllers/api/v1/registrant/base_controller.rb

@@ -0,0 +1,38 @@
+require 'rails5_api_controller_backport'
+require 'auth_token/auth_token_decryptor'
+
+module Api
+  module V1
+    module Registrant
+      class BaseController < ActionController::API
+        before_action :authenticate
+
+        rescue_from(ActionController::ParameterMissing) do |parameter_missing_exception|
+          error = {}
+          error[parameter_missing_exception.param] = ['parameter is required']
+          response = { errors: [error] }
+          render json: response, status: :unprocessable_entity
+        end
+
+        private
+
+        def bearer_token
+          pattern = /^Bearer /
+          header  = request.headers['Authorization']
+          header.gsub(pattern, '') if header&.match(pattern)
+        end
+
+        def authenticate
+          decryptor = AuthTokenDecryptor.create_with_defaults(bearer_token)
+          decryptor.decrypt_token
+
+          if decryptor.valid?
+            sign_in decryptor.user
+          else
+            render json: { errors: ['Not authorized'] }, status: :unauthorized
+          end
+        end
+      end
+    end
+  end
+end