Add global `locale` param (#17464)

- Remove the session-based locale stickyness

1 files changed, 13 insertions, 16 deletions

diff --git a/app/controllers/concerns/localized.rb b/app/controllers/concerns/localized.rb
index fe1142f34..f7b62f09c 100644
--- a/app/controllers/concerns/localized.rb
+++ b/app/controllers/concerns/localized.rb
@@ -7,27 +7,24 @@ module Localized
     around_action :set_locale
   end
 
-  def set_locale
-    locale   = current_user.locale if respond_to?(:user_signed_in?) && user_signed_in?
-    locale ||= session[:locale] ||= default_locale
-    locale   = default_locale unless I18n.available_locales.include?(locale.to_sym)
-
-    I18n.with_locale(locale) do
-      yield
-    end
+  def set_locale(&block)
+    I18n.with_locale(requested_locale || I18n.default_locale, &block)
   end
 
   private
 
-  def default_locale
-    if ENV['DEFAULT_LOCALE'].present?
-      I18n.default_locale
-    else
-      request_locale || I18n.default_locale
-    end
+  def requested_locale
+    requested_locale_name   = available_locale_or_nil(params[:locale])
+    requested_locale_name ||= available_locale_or_nil(current_user.locale) if respond_to?(:user_signed_in?) && user_signed_in?
+    requested_locale_name ||= http_accept_language if ENV['DEFAULT_LOCALE'].blank?
+    requested_locale_name
+  end
+
+  def http_accept_language
+    HttpAcceptLanguage::Parser.new(request.headers.fetch('Accept-Language')).language_region_compatible_from(I18n.available_locales) if request.headers.key?('Accept-Language')
   end
 
-  def request_locale
-    http_accept_language.language_region_compatible_from(I18n.available_locales)
+  def available_locale_or_nil(locale_name)
+    locale_name.to_sym if locale_name.present? && I18n.available_locales.include?(locale_name.to_sym)
   end
 end