Added optional two-factor authentication

app/views/auth/sessions/new.html.haml

@@ -4,6 +4,7 @@
 = simple_form_for(resource, as: resource_name, url: session_path(resource_name)) do |f|
   = f.input :email, autofocus: true, placeholder: t('simple_form.labels.defaults.email'), required: true, input_html: { 'aria-label' => t('simple_form.labels.defaults.email') }
   = f.input :password, placeholder: t('simple_form.labels.defaults.password'), required: true, input_html: { 'aria-label' => t('simple_form.labels.defaults.password') }
+  = f.input :otp_attempt, placeholder: t('simple_form.labels.defaults.otp_attempt'), input_html: { 'aria-label' => t('simple_form.labels.defaults.otp_attempt') }
 
   .actions
     = f.button :button, t('auth.login'), type: :submit

app/views/settings/shared/_links.html.haml

@@ -5,4 +5,6 @@
     %li= link_to t('settings.preferences'), settings_preferences_path
   - if controller_name != 'registrations'
     %li= link_to t('auth.change_password'), edit_user_registration_path
-  %li= link_to t('settings.back'), root_path
+  - if controller_name != 'two_factor_auths'
+    %li= link_to t('settings.two_factor_auth'), settings_two_factor_auth_path
+  %li= link_to t('settings.back'), root_path

app/views/settings/two_factor_auths/show.html.haml

@@ -0,0 +1,17 @@
+- content_for :page_title do
+  = t('settings.two_factor_auth')
+
+- if current_user.otp_required_for_login
+  %p= t('two_factor_auth.instructions_html')
+
+  .qr-code= raw @qrcode.as_svg(padding: 0, module_size: 5)
+
+  .simple_form
+    = link_to t('two_factor_auth.disable'), disable_settings_two_factor_auth_path, data: { method: 'POST' }, class: 'block-button'
+- else
+  %p= t('two_factor_auth.description_html')
+
+  .simple_form
+    = link_to t('two_factor_auth.enable'), enable_settings_two_factor_auth_path, data: { method: 'POST' }, class: 'block-button'
+
+.form-footer= render "settings/shared/links"