fix: Locale not correct in root url when accessing help center with custom domain (#9110)

- Ensuring that SwitchLocale concern handles the case of custom domain for portals and set locale according to that

Co-authored-by: Sojan Jose <sojan@pepalo.com>

app/controllers/concerns/domain_helper.rb

@@ -0,0 +1,5 @@
+module DomainHelper
+  def self.chatwoot_domain?(domain = request.host)
+    [URI.parse(ENV.fetch('FRONTEND_URL', '')).host, URI.parse(ENV.fetch('HELPCENTER_URL', '')).host].include?(domain)
+  end
+end

app/controllers/concerns/switch_locale.rb

@@ -6,6 +6,7 @@ module SwitchLocale
   def switch_locale(&)
     # priority is for locale set in query string (mostly for widget/from js sdk)
     locale ||= locale_from_params
+    locale ||= locale_from_custom_domain
     # if locale is not set in account, let's use DEFAULT_LOCALE env variable
     locale ||= locale_from_env_variable
     set_locale(locale, &)
@@ -16,6 +17,20 @@ module SwitchLocale
     set_locale(locale, &)
   end
 
+  # If the request is coming from a custom domain, it should be for a helpcenter portal
+  # We will use the portal locale in such cases
+  def locale_from_custom_domain(&)
+    return if params[:locale]
+
+    domain = request.host
+    return if DomainHelper.chatwoot_domain?(domain)
+
+    @portal = Portal.find_by(custom_domain: domain)
+    return unless @portal
+
+    @portal.default_locale
+  end
+
   def set_locale(locale, &)
     # if locale is empty, use default_locale
     locale ||= I18n.default_locale