Refactor voucher_processor into model concern

According to concepts discussed in #694.
Also auto-load subdirectories in models folder
and set Current.user for usage in models.

app/controllers/application_controller.rb

@@ -8,6 +8,7 @@ class ApplicationController < ActionController::Base
   before_action :authenticate_user!
   before_action :set_locale
   after_action :store_interaction, if: :user_signed_in?
+  before_action :set_current_user
 
   etag { current_user.try(:id) }
 
@@ -135,4 +136,9 @@ def cookie_locale_param
     def available_locales
       I18n.available_locales.map(&:to_s)
     end
+
+    # https://stackoverflow.com/a/69313330/
+    def set_current_user
+      Current.user = current_user
+    end
 end

app/controllers/vouchers_controller.rb

@@ -28,7 +28,7 @@ def invalidate
   end
 
   def verify
-    @voucher = Voucher.find_voucher_by_hash(check_voucher_params[:secure_hash])
+    @voucher = Voucher.find_voucher_by_hash(params[:secure_hash])
     respond_to do |format|
       if @voucher
         format.js
@@ -42,9 +42,9 @@ def verify
   end
 
   def redeem
-    voucher = Voucher.find_voucher_by_hash(check_voucher_params[:secure_hash])
+    voucher = Voucher.find_voucher_by_hash(params[:secure_hash])
     if voucher
-      VoucherProcessor.call(voucher, current_user, check_voucher_params)
+      voucher.redeem(params.permit(:tutorial_ids, :talk_ids))
       redirect_to edit_profile_path, notice: success_message(voucher)
     else
       handle_invalid_voucher
@@ -64,10 +64,6 @@ def voucher_params
       params.permit(:lecture_id, :role)
     end
 
-    def check_voucher_params
-      params.permit(:secure_hash, tutorial_ids: [], talk_ids: [])
-    end
-
     def find_voucher
       @voucher = Voucher.find_by(id: params[:id])
       return if @voucher

app/models/current.rb

@@ -0,0 +1,4 @@
+# https://api.rubyonrails.org/classes/ActiveSupport/CurrentAttributes.html
+class Current < ActiveSupport::CurrentAttributes
+  attribute :user
+end

app/models/voucher/redeemable.rb

@@ -0,0 +1,68 @@
+module Redeemable
+  extend ActiveSupport::Concern
+  include Notifier
+
+  included do
+    has_many :redemptions, dependent: :destroy
+  end
+
+  def redeem(params)
+    case role.to_sym
+    when :tutor
+      process_tutor_voucher(params[:tutorial_ids])
+    when :editor
+      process_editor_voucher
+    when :teacher
+      process_teacher_voucher
+    when :speaker
+      process_speaker_voucher(params[:talk_ids])
+    end
+  end
+
+  private
+
+    def process_tutor_voucher(tutorial_ids)
+      selected_tutorials = lecture.tutorials.where(id: tutorial_ids)
+      lecture.update_tutor_status!(Current.user, selected_tutorials)
+
+      Redemption.create(user: Current.user, voucher: self,
+                        claimed_tutorials: selected_tutorials)
+    end
+
+    def process_editor_voucher
+      lecture.update_editor_status!(Current.user)
+      notify_new_editor_by_mail(Current.user, lecture)
+
+      Redemption.create(user: Current.user, voucher: self)
+    end
+
+    def process_teacher_voucher
+      previous_teacher = lecture.teacher
+      lecture.update_teacher_status!(Current.user)
+      # no need to send out notifications if the teacher stays the same
+      # because then there is no demotion to editor
+      # (it is actually not possible to trigger this case via the GUI)
+      if previous_teacher != Current.user
+        notify_about_teacher_change_by_mail(lecture,
+                                            previous_teacher)
+      end
+      invalidate!
+
+      Redemption.create(user: Current.user, voucher: self)
+    end
+
+    def process_speaker_voucher(talk_ids)
+      selected_talks = lecture.talks.where(id: talk_ids)
+      lecture.update_speaker_status!(Current.user, selected_talks)
+      notify_cospeakers_by_mail(Current.user, selected_talks)
+
+      Redemption.create(user: Current.user, voucher: self,
+                        claimed_talks: selected_talks)
+    end
+
+    def create_notifications!(redemption)
+      lecture.editors_and_teacher.each do |editor|
+        Notification.create(notifiable: redemption, recipient: editor)
+      end
+    end
+end

app/models/voucher.rb → app/models/voucher/voucher.rb

@@ -1,4 +1,6 @@
 class Voucher < ApplicationRecord
+  include Redeemable
+
   SPEAKER_EXPIRATION_DAYS = 30
   TUTOR_EXPIRATION_DAYS = 14
   DEFAULT_EXPIRATION_DAYS = 3

config/application.rb

@@ -12,6 +12,10 @@ class Application < Rails::Application
     config.load_defaults(7.1)
     config.autoloader = :zeitwerk
 
+    # Autoload subfolders of modules (recursively)
+    # https://stackoverflow.com/a/4794775/
+    config.autoload_paths += Rails.root.glob("app/models/**/")
+
     # Autoload lib extensions path
     config.autoload_lib(ignore: ["assets", "collectors", "core_ext", "scrapers", "tasks"])