Add toggle to enable/disable joining via coursecode

app/controllers/courses_controller.rb

@@ -336,8 +336,15 @@ def import_details
   def update_coursecode
     authorize @course, :update?
 
-    @course.generate_coursecode!
-    flash.now[:notice] = 'Course join code successfully generated'
+    if params[:generate] == 'true'
+      @course.generate_coursecode!
+      flash.now[:notice] = 'Course join code successfully generated'
+    end
+
+    if params[:course]&.key?(:coursecode_enabled)
+      @course.update!(coursecode_enabled: params[:course][:coursecode_enabled])
+      flash.now[:notice] ||= 'Course join code settings updated'
+    end
   rescue StandardError => e
     flash.now[:alert] = e.message
   ensure
@@ -348,19 +355,14 @@ def update_coursecode
   end
 
   def enroll_via_coursecode
-    code = params[:coursecode]
-    @course = Course.by_coursecode(code).first
-
-    if @course
-      Enrolment.find_or_create_by!(
-        user: current_user,
-        course: @course,
-        role: :student
-      )
-      redirect_back_or_to '/', notice: 'Successfully joined the course.'
+    new_enrolment = Enrolment.enroll_via_coursecode(current_user, params[:coursecode])
+    if new_enrolment
+      redirect_back_or_to '/', notice: 'Successfully joined the course'
     else
-      redirect_back_or_to '/', alert: 'Invalid course code.'
+      redirect_back_or_to '/', notice: 'You already joined the course'
     end
+  rescue StandardError => e
+    redirect_back_or_to '/', alert: e.message
   end
 
   private

app/javascript/controllers/coursecode_form_handler_controller.js

@@ -0,0 +1,16 @@
+import { Controller } from "@hotwired/stimulus";
+
+// Connects to data-controller="coursecode-form-handler"
+export default class extends Controller {
+  static targets = ["generateFlag"];
+
+  submitForm() {
+    this.element.requestSubmit();
+  }
+
+  generateCode(event) {
+    event.preventDefault();
+    this.generateFlagTarget.value = "true";
+    this.element.requestSubmit();
+  }
+}

app/models/enrolment.rb

@@ -4,4 +4,22 @@ class Enrolment < ApplicationRecord
 
   has_many :projects, dependent: :destroy
   enum :role, { lecturer: 0, coordinator: 1, student: 2 }
+
+  # Enrolls a user in a course using a course code.
+  # Validates that the course exists and that joining via course code is enabled.
+  # Returns true if the user was newly enrolled, or false if they were already enrolled.
+  def self.enroll_via_coursecode(user, code)
+    course = Course.by_coursecode(code).first
+
+    raise 'Invalid course code' unless course
+    raise 'Joining via course code is disabled for this course' unless course.coursecode_enabled
+
+    enrolment = find_or_create_by!(
+      user: user,
+      course: course,
+      role: :student
+    )
+
+    enrolment.previously_new_record?
+  end
 end

app/views/courses/_course_code_form.html.erb

@@ -1,6 +1,6 @@
 <%= turbo_frame_tag "course_code_form" do %>
   <div class="bg-white py-8 px-4 shadow sm:rounded-lg sm:px-10 max-w-3xl mx-auto border border-gray-100 mb-6">
-    <%= form_with url: update_coursecode_course_path(@course), model: @course, method: :post  do |form| %>
+    <%= form_with url: update_coursecode_course_path(@course), model: @course, method: :post, data: { controller: "coursecode-form-handler" } do |form| %>
       <%= form.label :coursecode,
         'Course Join Code & Invite Link',
         class: "block text-sm font-medium text-gray-700" %>
@@ -10,11 +10,16 @@
           readonly: true,
           disabled: true,
           class: "appearance-none block w-[10em] font-mono px-3 py-2 border border-gray-300 rounded-md shadow-sm placeholder-gray-400 focus:outline-none focus:ring-green-500 focus:border-green-500 sm:text-sm" %>
-        <button
-                class="px-4 py-2 bg-blue-200 hover:bg-blue-300 text-gray-800 text-sm font-medium rounded shadow-sm">
+        <button id="regenerate-code-btn" type="button" data-action="click->coursecode-form-handler#generateCode" class="px-4 py-2 bg-blue-200 hover:bg-blue-300 text-gray-800 text-sm font-medium rounded shadow-sm">
           <%= @course.coursecode.present? ? 'Re-Generate Join Code' : 'Generate Join code' %>
         </button>
       </div>
+      <input type="hidden" name="generate" value="false" data-coursecode-form-handler-target="generateFlag">
+      <label class="inline-flex items-center cursor-pointer mt-4">
+        <%= form.check_box :coursecode_enabled, class: "sr-only peer", role: "switch", data: { action: "change->coursecode-form-handler#submitForm" } %>
+        <div class="relative w-11 h-6 bg-gray-400 peer-focus:outline-none rounded-full peer peer-checked:after:translate-x-full peer-checked:after:border-white after:content-[''] after:absolute after:top-[10%] after:left-[5%] after:bg-white after:border-gray-300 after:border after:rounded-full after:h-[80%] after:w-[45%] after:transition-all peer-checked:bg-green-500"></div>
+        <span class="ml-3 text-sm font-medium text-gray-700">Allow joining via course code</span>
+      </label>
     <% end %>
   </div>
 <% end %>

app/views/project_templates/edit.html.erb

@@ -72,7 +72,7 @@
                 Req.
               </th>
               <th scope="col" class="px-2 py-5 text-center text-[10px] font-bold text-gray-500 uppercase tracking-normal leading-4 w-[8%]">
-                Editable <br/> Post-Approval
+                Editable <br> Post-Approval
               </th>
             </tr>
           </thead>

db/migrate/20260406172051_add_coursecode_enabled_to_courses.rb

@@ -0,0 +1,5 @@
+class AddCoursecodeEnabledToCourses < ActiveRecord::Migration[8.0]
+  def change
+    add_column :courses, :coursecode_enabled, :boolean, null: false, default: false
+  end
+end

test/integration/enroll_via_coursecode_test.rb

@@ -9,6 +9,8 @@ class EnrollViaCoursecodeTest < ActionDispatch::IntegrationTest
   end
 
   test 'should successfully enroll in course with valid coursecode' do
+    @course.update!(coursecode_enabled: true)
+
     # Sign in the student
     post session_path, params: { email_address: @student.email_address, password: 'password' }
     assert_redirected_to root_path
@@ -21,12 +23,28 @@ class EnrollViaCoursecodeTest < ActionDispatch::IntegrationTest
 
     # The student is redirected to '/' and sees a success message
     assert_redirected_to '/'
-    assert_equal 'Successfully joined the course.', flash[:notice]
+    assert_equal 'Successfully joined the course', flash[:notice]
 
     # Verify that an enrolment was created
     assert @course.students.include?(@student)
   end
 
+  test 'should notify students that they are already enrolled in the course' do
+    @course.update!(coursecode_enabled: true)
+
+    # Sign in the student
+    post session_path, params: { email_address: @student.email_address, password: 'password' }
+    assert_redirected_to root_path
+
+    # Submit valid coursecode (and again)
+    post invite_path, params: { coursecode: @course.coursecode }
+    post invite_path, params: { coursecode: @course.coursecode }
+
+    # The student is redirected to '/' and sees a success message
+    assert_redirected_to '/'
+    assert_equal 'You already joined the course', flash[:notice]
+  end
+
   test 'should display error for invalid coursecode' do
     # Sign in the student
     post session_path, params: { email_address: @student.email_address, password: 'password' }
@@ -37,7 +55,7 @@ class EnrollViaCoursecodeTest < ActionDispatch::IntegrationTest
 
     # Student cannot join, is redirected with an error alert
     assert_redirected_to '/'
-    assert_equal 'Invalid course code.', flash[:alert]
+    assert_equal 'Invalid course code', flash[:alert]
 
     # Check that they did not join the course
     assert_not @course.students.include?(@student)

test/integration/update_coursecode_test.rb

@@ -12,11 +12,9 @@ class UpdateCoursecodeTest < ActionDispatch::IntegrationTest
     post session_path, params: { email_address: @lecturer.email_address, password: 'password' }
     assert_redirected_to root_path
 
-    # Initial state
     assert_nil @course.coursecode
 
-    # Call the API explicitly
-    post update_coursecode_course_path(@course), headers: { 'Accept' => 'text/vnd.turbo-stream.html' }
+    post update_coursecode_course_path(@course), params: { generate: true }, headers: { 'Accept' => 'text/vnd.turbo-stream.html' }
 
     # The request should succeed and return turbo stream content
     assert_response :success
@@ -30,4 +28,23 @@ class UpdateCoursecodeTest < ActionDispatch::IntegrationTest
     # It replaces the 'course_code_form' which contains the new course code string.
     assert_match @course.coursecode, response.body
   end
+
+  test 'should toggle the coursecode_enabled field in courses' do
+    # Sign in the lecturer (coordinator)
+    post session_path, params: { email_address: @lecturer.email_address, password: 'password' }
+    assert_redirected_to root_path
+
+    assert_nil @course.coursecode
+    assert_equal @course.coursecode_enabled, false
+
+    post update_coursecode_course_path(@course), params: { course: { coursecode_enabled: true } }, headers: { 'Accept' => 'text/vnd.turbo-stream.html' }
+
+    # The request should succeed and return turbo stream content
+    assert_response :success
+    assert_equal 'text/vnd.turbo-stream.html', response.media_type
+
+    # The coursecode_enabled must be set to true
+    @course.reload
+    assert_equal @course.coursecode_enabled, true
+  end
 end