add endpoint to check for exercise uuid

app/controllers/exercises_controller.rb

@@ -12,9 +12,9 @@ class ExercisesController < ApplicationController
   before_action :set_file_types, only: [:create, :edit, :new, :update]
   before_action :set_course_token, only: [:implement]
 
-  skip_before_action :verify_authenticity_token, only: [:import_proforma_xml]
+  skip_before_action :verify_authenticity_token, only: [:import_proforma_xml, :import_uuid_check]
-  skip_after_action :verify_authorized, only: [:import_proforma_xml]
+  skip_after_action :verify_authorized, only: [:import_proforma_xml, :import_uuid_check]
-  skip_after_action :verify_policy_scoped, only: [:import_proforma_xml], raise: false
+  skip_after_action :verify_policy_scoped, only: [:import_proforma_xml, :import_uuid_check], raise: false
 
   def authorize!
     authorize(@exercise || @exercises)
@@ -119,6 +119,15 @@ class ExercisesController < ApplicationController
     end
   end
 
+  def import_uuid_check
+    uuid = params[:uuid]
+    exercise = Exercise.find_by(uuid: uuid)
+
+    return render json: {exercise_found: false, message: 'no_exercise'} if exercise.nil?
+
+    render json: {exercise_found: true, message: 'exercise found, be careful when overwriting or else!'}
+  end
+
   def import_proforma_xml
     tempfile = Tempfile.new('codeharbor_import.zip')
     tempfile.write request.body.read.force_encoding('UTF-8')

config/routes.rb

@@ -67,6 +67,7 @@ Rails.application.routes.draw do
   end
 
   post '/import_proforma_xml' => 'exercises#import_proforma_xml'
+  post '/import_uuid_check' => 'exercises#import_uuid_check'
 
   resources :exercises do
     collection do