Change OpenGraph description on sign-up page to reflect invite (#11744)

app/helpers/instance_helper.rb

@@ -8,4 +8,16 @@ module InstanceHelper
   def site_hostname
     @site_hostname ||= Addressable::URI.parse("//#{Rails.configuration.x.local_domain}").display_uri.host
   end
+
+  def description_for_sign_up
+    prefix = begin
+      if @invite.present?
+        I18n.t('auth.description.prefix_invited_by_user', name: @invite.user.account.username)
+      else
+        I18n.t('auth.description.prefix_sign_up')
+      end
+    end
+
+    safe_join([prefix, I18n.t('auth.description.suffix')], ' ')
+  end
 end

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

@@ -2,7 +2,7 @@
   = t('auth.register')
 
 - content_for :header_tags do
-  = render partial: 'shared/og'
+  = render partial: 'shared/og', locals: { description: description_for_sign_up }
 
 = simple_form_for(resource, as: resource_name, url: registration_path(resource_name)) do |f|
   = render 'shared/error_messages', object: resource

app/views/shared/_og.html.haml

@@ -1,5 +1,5 @@
-- thumbnail = @instance_presenter.thumbnail
-- description = strip_tags(@instance_presenter.site_short_description.presence || @instance_presenter.site_description.presence || t('about.about_mastodon_html'))
+- thumbnail     = @instance_presenter.thumbnail
+- description ||= strip_tags(@instance_presenter.site_short_description.presence || @instance_presenter.site_description.presence || t('about.about_mastodon_html'))
 
 %meta{ name: 'description', content: description }/