Redirect users after sign in to their desired page

app/controllers/application_controller.rb

@@ -127,11 +127,14 @@ class ApplicationController < ActionController::Base
     respond_to do |format|
       format.any do
         # Prevent redirect loop
-        if request.url == request.referer
+        if request.url == request.referer || request.referer&.match?(sign_in_path)
           redirect_to :root, alert: message
         # Redirect to main domain if the request originated from our render_host
         elsif request.path == '/' && request.host == RENDER_HOST
           redirect_to Rails.application.config.action_mailer.default_url_options, allow_other_host: true
+        elsif current_user.nil? && status == :unauthorized
+          session[:return_to_url] = request.fullpath if current_user.nil?
+          redirect_to sign_in_path, alert: t('application.not_signed_in')
         else
           redirect_back fallback_location: :root, allow_other_host: false, alert: message
         end

app/views/sessions/new.html.slim

@@ -1,5 +1,13 @@
 h1 = t('.headline')
 
+.lead
+  .card.border-info-subtle.mb-3
+    .card-header
+      i.fa-solid.fa-circle-info.text-info
+      strong.text-info
+        => t('.instructors_only')
+      = t('.instructors_only_explanation', application_name:)
+
 = form_tag(sessions_path) do
   .mb-3
     = label_tag(:email, t('activerecord.attributes.internal_user.email'))

config/locales/de.yml

@@ -294,6 +294,7 @@ de:
   application:
     not_authorized: Sie sind nicht berechtigt, diese Aktion auszuführen.
     not_found: Die angeforderte Ressource konnte nicht gefunden werden.
+    not_signed_in: Sie müssen angemeldet sein, um diese Aktion auszuführen.
     welcome:
       text_signed_in_as_external_user: 'Bitte rufen Sie %{application_name} von einer E-Learning-Plattform auf.'
       text_signed_in_as_internal_user: 'Schön, Sie zu sehen, %{user_name}!'
@@ -892,6 +893,8 @@ de:
     new:
       forgot_password: Passwort vergessen?
       headline: Anmelden
+      instructors_only: 'Zugriff ausschließlich für Lehrende:'
+      instructors_only_explanation: Das Anmelden mittels Passwort ist ausschließlich Lehrenden vorbehalten. Als Lernende:r greifen Sie bitte über die E-Learning-Plattform auf %{application_name} zu, um direkt zu einer Aufgabe zu gelangen.
       link: Anmelden
       remember_me: Angemeldet bleiben
     oauth:

config/locales/en.yml

@@ -294,6 +294,7 @@ en:
   application:
     not_authorized: You are not authorized to perform this action.
     not_found: The requested resource could not be found.
+    not_signed_in: You must be signed in to perform this action.
     welcome:
       text_signed_in_as_external_user: 'Please access %{application_name} from an e-learning platform.'
       text_signed_in_as_internal_user: 'Good to see you, %{user_name}!'
@@ -893,6 +894,8 @@ en:
       forgot_password: Forgot password?
       headline: Sign In
       link: Sign In
+      instructors_only: 'Exclusive access for instructors:'
+      instructors_only_explanation: Signing in via password is reserved exclusively for instructors. As a learner, please access %{application_name} via the e-learning platform to proceed directly to an exercise.
       remember_me: Remember me
     oauth:
       failure: 'Sorry, something went wrong.'

spec/controllers/application_controller_spec.rb

@@ -30,11 +30,26 @@ RSpec.describe ApplicationController do
   describe '#render_not_authorized' do
     before do
       allow(controller).to receive(:welcome) { controller.send(:render_not_authorized) }
+      login_user(user) if defined?(user)
       get :welcome
     end
 
-    expect_flash_message(:alert, I18n.t('application.not_authorized'))
-    expect_redirect(:root)
+    expect_flash_message(:alert, I18n.t('application.not_signed_in'))
+    expect_redirect(:sign_in)
+
+    context 'with an admin' do
+      let(:user) { create(:admin) }
+
+      expect_flash_message(:alert, I18n.t('application.not_authorized'))
+      expect_redirect(:root)
+    end
+
+    context 'with a teacher' do
+      let(:user) { create(:teacher) }
+
+      expect_flash_message(:alert, I18n.t('application.not_authorized'))
+      expect_redirect(:root)
+    end
   end
 
   describe '#render_not_found' do
@@ -44,19 +59,21 @@ RSpec.describe ApplicationController do
       get :welcome
     end
 
-    expect_flash_message(:alert, I18n.t('application.not_authorized'))
-    expect_redirect(:root)
+    expect_flash_message(:alert, I18n.t('application.not_signed_in'))
+    expect_redirect(:sign_in)
 
     context 'with an admin' do
       let(:user) { create(:admin) }
 
       expect_flash_message(:alert, I18n.t('application.not_found'))
+      expect_redirect(:root)
     end
 
     context 'with a teacher' do
       let(:user) { create(:teacher) }
 
       expect_flash_message(:alert, I18n.t('application.not_authorized'))
+      expect_redirect(:root)
     end
   end
 

spec/controllers/internal_users_controller_spec.rb

@@ -19,7 +19,7 @@ RSpec.describe InternalUsersController do
     context 'without a valid activation token' do
       before { get :activate, params: {id: user.id} }
 
-      expect_redirect(:root)
+      expect_redirect(:sign_in)
     end
 
     context 'with an already activated user' do
@@ -28,7 +28,7 @@ RSpec.describe InternalUsersController do
         get :activate, params: {id: user.id, token: user.activation_token}
       end
 
-      expect_redirect(:root)
+      expect_redirect(:sign_in)
     end
 
     context 'with valid preconditions' do
@@ -56,7 +56,7 @@ RSpec.describe InternalUsersController do
     context 'without a valid activation token' do
       before { put :activate, params: {id: user.id} }
 
-      expect_redirect(:root)
+      expect_redirect(:sign_in)
     end
 
     context 'with an already activated user' do
@@ -65,7 +65,7 @@ RSpec.describe InternalUsersController do
         put :activate, params: {id: user.id, internal_user: {activation_token: user.activation_token, password:, password_confirmation: password}}
       end
 
-      expect_redirect(:root)
+      expect_redirect(:sign_in)
     end
 
     context 'without a password' do
@@ -249,7 +249,7 @@ RSpec.describe InternalUsersController do
     context 'without a valid password reset token' do
       before { get :reset_password, params: {id: user.id} }
 
-      expect_redirect(:root)
+      expect_redirect(:sign_in)
     end
 
     context 'with a valid password reset token' do
@@ -270,7 +270,7 @@ RSpec.describe InternalUsersController do
     context 'without a valid password reset token' do
       before { put :reset_password, params: {id: user.id} }
 
-      expect_redirect(:root)
+      expect_redirect(:sign_in)
     end
 
     context 'with a valid password reset token' do

spec/features/authentication_spec.rb

@@ -3,8 +3,8 @@
 require 'rails_helper'
 
 RSpec.describe 'Authentication' do
-  let(:user) { create(:admin) }
-  let(:password) { attributes_for(:admin)[:password] }
+  let(:user) { create(:teacher) }
+  let(:password) { attributes_for(:teacher)[:password] }
 
   context 'when signed out' do
     before { visit(root_path) }
@@ -33,6 +33,38 @@ RSpec.describe 'Authentication' do
       end
     end
 
+    context 'when a restricted sub-page is opened' do
+      let(:exercise) { create(:math, user:, public: false) }
+
+      before { visit(exercise_path(exercise)) }
+
+      it 'displays a sign in link' do
+        expect(page).to have_content(I18n.t('sessions.new.link'))
+      end
+
+      it 'shows a notification' do
+        expect(page).to have_content(I18n.t('application.not_signed_in'))
+      end
+
+      it 'redirects to the desired page immediately after sign-in' do
+        fill_in('Email', with: user.email)
+        fill_in('Password', with: password)
+        click_button(I18n.t('sessions.new.link'))
+        expect(page).to have_content(exercise.title)
+      end
+
+      context 'when a user still has no access' do
+        let(:exercise) { create(:math, public: false) }
+
+        it 'informs the user about missing permissions' do
+          fill_in('Email', with: user.email)
+          fill_in('Password', with: password)
+          click_button(I18n.t('sessions.new.link'))
+          expect(page).to have_content(I18n.t('application.not_authorized'))
+        end
+      end
+    end
+
     context 'with no authentication token' do
       let(:request_for_comment) { create(:rfc_with_comment, user:) }
       let(:rfc_path) { request_for_comment_url(request_for_comment) }
@@ -41,8 +73,8 @@ RSpec.describe 'Authentication' do
         visit(rfc_path)
         expect(page).not_to have_current_path(rfc_path)
         expect(page).not_to have_content(request_for_comment.exercise.title)
-        expect(page).to have_current_path(root_path)
-        expect(page).to have_content(I18n.t('application.not_authorized'))
+        expect(page).to have_current_path(sign_in_path)
+        expect(page).to have_content(I18n.t('application.not_signed_in'))
       end
     end
 
@@ -75,8 +107,8 @@ RSpec.describe 'Authentication' do
           visit(rfc_link)
           expect(page).not_to have_current_path(rfc_link)
           expect(page).not_to have_content(request_for_comment.exercise.title)
-          expect(page).to have_current_path(root_path)
-          expect(page).to have_content(I18n.t('application.not_authorized'))
+          expect(page).to have_current_path(sign_in_path)
+          expect(page).to have_content(I18n.t('application.not_signed_in'))
         end
       end
 
@@ -95,7 +127,7 @@ RSpec.describe 'Authentication' do
           expect(page).to have_current_path(rfc_link)
           visit(sign_out_path)
           visit(rfc_link)
-          expect(page).to have_current_path(root_path)
+          expect(page).to have_current_path(sign_in_path)
         end
       end
     end