Improve multi language support

api/app/controllers/spree/api/base_controller.rb

@@ -6,6 +6,7 @@ class BaseController < ActionController::API
       include Spree::Api::ControllerSetup
       include Spree::Core::ControllerHelpers::Store
       include Spree::Core::ControllerHelpers::StrongParameters
+      include Spree::Core::ControllerHelpers::Locale
       include Spree::Core::ControllerHelpers::Currency
 
       attr_accessor :current_api_user

api/app/controllers/spree/api/v2/base_controller.rb

@@ -5,13 +5,12 @@ class BaseController < ActionController::API
         include CanCan::ControllerAdditions
         include Spree::Core::ControllerHelpers::StrongParameters
         include Spree::Core::ControllerHelpers::Store
+        include Spree::Core::ControllerHelpers::Locale
         include Spree::Core::ControllerHelpers::Currency
         rescue_from ActiveRecord::RecordNotFound, with: :record_not_found
         rescue_from CanCan::AccessDenied, with: :access_denied
         rescue_from Spree::Core::GatewayError, with: :gateway_error
 
-        before_action :set_user_language
-
         def content_type
           Spree::Api::Config[:api_v2_content_type]
         end
@@ -96,10 +95,6 @@ def access_denied(exception)
         def gateway_error(exception)
           render_error_payload(exception.message)
         end
-
-        def set_user_language
-          I18n.locale = current_store.default_locale
-        end
       end
     end
   end

backend/app/controllers/spree/admin/base_controller.rb

@@ -2,6 +2,7 @@ module Spree
   module Admin
     class BaseController < Spree::BaseController
       helper 'spree/admin/navigation'
+      helper 'spree/locale'
       layout 'spree/layouts/admin'
 
       before_action :authorize_admin

backend/app/controllers/spree/admin/stores_controller.rb

@@ -9,8 +9,6 @@ class StoresController < Spree::Admin::BaseController
       before_action :load_all_countries, only: [:new, :edit, :update, :create]
       before_action :load_all_zones, only: %i[new edit]
 
-      helper_method :all_locales_options
-
       def index
         if params[:ids]
           load_stores_by_ids
@@ -132,18 +130,6 @@ def normalize_supported_currencies
       def set_default_country_id
         @store.default_country_id = Spree::Config[:default_country_id]
       end
-
-      def all_locales_options
-        if defined?(SpreeI18n)
-          SpreeI18n::Locale.all.map { |locale| locale_presentation(locale) }.push(['English (EN)', :en])
-        else
-          [['English (EN)', :en]]
-        end
-      end
-
-      def locale_presentation(locale)
-        [Spree.t('i18n.this_file_language', locale: locale), locale]
-      end
     end
   end
 end

core/app/controllers/spree/base_controller.rb

@@ -7,6 +7,7 @@ class Spree::BaseController < ApplicationController
   include Spree::Core::ControllerHelpers::Search
   include Spree::Core::ControllerHelpers::Store
   include Spree::Core::ControllerHelpers::StrongParameters
+  include Spree::Core::ControllerHelpers::Locale
   include Spree::Core::ControllerHelpers::Currency
 
   respond_to :html

core/app/helpers/spree/locale_helper.rb

@@ -0,0 +1,19 @@
+module Spree
+  module LocaleHelper
+    def all_locales_options
+      supported_locales_for_all_stores.map { |locale| locale_presentation(locale) }
+    end
+
+    def available_locales_options
+      available_locales.map { |locale| locale_presentation(locale) }
+    end
+
+    def locale_presentation(locale)
+      if defined?(SpreeI18n)
+        [Spree.t('i18n.this_file_language', locale: locale), locale]
+      else
+        locale.to_s == 'en' ? ['English (US)', :en] : [locale, locale]
+      end
+    end
+  end
+end

core/app/models/spree/store.rb

@@ -43,36 +43,47 @@ def self.default
       end
     end
 
+    def self.available_locales
+      Rails.cache.fetch('stores_available_locales') do
+        Spree::Store.all.map(&:supported_locales_list).flatten.uniq
+      end
+    end
+
     def supported_currencies_list
-      (read_attribute(:supported_currencies).to_s.split(',') << default_currency).map(&:to_s).map do |code|
+      @supported_currencies_list ||= (read_attribute(:supported_currencies).to_s.split(',') << default_currency).map(&:to_s).map do |code|
         ::Money::Currency.find(code.strip)
       end.uniq.compact
     end
 
+    def supported_locales_list
+      # TODO: add support of multiple supported languages to a single Store
+      @supported_locales_list ||= [default_locale].compact.uniq
+    end
+
     def unique_name
-      "#{name} (#{code})"
+      @unique_name ||= "#{name} (#{code})"
     end
 
     def formatted_url
       return if url.blank?
 
-      if url.match(/http:\/\/|https:\/\//)
-        url
-      else
-        Rails.env.development? ? "http://#{url}" : "https://#{url}"
-      end
+      @formatted_url ||= if url.match(/http:\/\/|https:\/\//)
+                           url
+                         else
+                           Rails.env.development? ? "http://#{url}" : "https://#{url}"
+                         end
     end
 
     def countries_available_for_checkout
-      checkout_zone_or_default.try(:country_list) || Spree::Country.all
+      @countries_available_for_checkout ||= checkout_zone_or_default.try(:country_list) || Spree::Country.all
     end
 
     def states_available_for_checkout(country)
       checkout_zone_or_default.try(:state_list_for, country) || country.states
     end
 
     def checkout_zone_or_default
-      checkout_zone || Spree::Zone.default_checkout_zone
+      @checkout_zone_or_default ||= checkout_zone || Spree::Zone.default_checkout_zone
     end
 
     private
@@ -94,6 +105,7 @@ def validate_not_default
 
     def clear_cache
       Rails.cache.delete('default_store')
+      Rails.cache.delete('stores_available_locales')
     end
   end
 end

core/lib/spree/core.rb

@@ -105,4 +105,5 @@ class DestroyWithOrdersError < StandardError; end
 require 'spree/core/controller_helpers/search'
 require 'spree/core/controller_helpers/store'
 require 'spree/core/controller_helpers/strong_parameters'
+require 'spree/core/controller_helpers/locale'
 require 'spree/core/controller_helpers/currency'

core/lib/spree/core/controller_helpers/common.rb

@@ -10,8 +10,6 @@ module Common
 
           layout :get_layout
 
-          before_action :set_user_language
-
           protected
 
           # can be used in views as well as controllers.
@@ -43,12 +41,12 @@ def accurate_title
           private
 
           def set_user_language
-            locale = session[:locale]
-            locale = store_locale if respond_to?(:store_locale, true) && locale.blank?
-            locale = config_locale if respond_to?(:config_locale, true) && locale.blank?
-            locale = Rails.application.config.i18n.default_locale if locale.blank?
-            locale = I18n.default_locale unless I18n.available_locales.map(&:to_s).include?(locale.to_s)
-            I18n.locale = locale
+            ActiveSupport::Deprecation.warn(<<-DEPRECATION, caller)
+              ControllerHelpers::Common#set_user_language is deprecated and will be removed in Spree 5.0.
+              Please use `before_action :set_locale` instead
+            DEPRECATION
+
+            set_locale
           end
 
           # Returns which layout to render.

core/lib/spree/core/controller_helpers/locale.rb

@@ -0,0 +1,57 @@
+module Spree
+  module Core
+    module ControllerHelpers
+      module Locale
+        extend ActiveSupport::Concern
+
+        included do
+          before_action :set_locale
+
+          helper_method :supported_locales
+          helper_method :supported_locales_for_all_stores
+          helper_method :current_locale
+          helper_method :supported_locale?
+          helper_method :available_locales
+        end
+
+        def set_locale
+          I18n.locale = current_locale
+        end
+
+        def current_locale
+          # session support was previously in SpreeI18n so we would like to keep it for now
+          # for easer upgrade
+          @current_locale ||= if defined?(session) && session.key?(:locale) && supported_locale?(session[:locale])
+                                session[:locale]
+                              elsif params[:locale].present? && supported_locale?(params[:locale])
+                                params[:locale]
+                              elsif respond_to?(:config_locale, true) && config_locale.present?
+                                config_locale
+                              else
+                                current_store.default_locale || Rails.application.config.i18n.default_locale || I18n.default_locale
+                              end
+        end
+
+        def supported_locales
+          @supported_locales ||= current_store.supported_locales_list
+        end
+
+        def supported_locale?(locale_code)
+          supported_locales.include?(locale_code&.to_s)
+        end
+
+        def supported_locales_for_all_stores
+          @supported_locales_for_all_stores ||= (if defined?(SpreeI18n)
+                                                   (SpreeI18n::Locale.all << :en).map(&:to_s)
+                                                 else
+                                                   [Rails.application.config.i18n.default_locale, I18n.locale, :en]
+                                                 end).uniq.compact
+        end
+
+        def available_locales
+          Spree::Store.available_locales
+        end
+      end
+    end
+  end
+end

core/spec/lib/spree/core/controller_helpers/locale_spec.rb

@@ -0,0 +1,66 @@
+require 'spec_helper'
+
+class FakesController < ApplicationController
+  include Spree::Core::ControllerHelpers::Auth
+  include Spree::Core::ControllerHelpers::Order
+  include Spree::Core::ControllerHelpers::Store
+  include Spree::Core::ControllerHelpers::Locale
+end
+
+class FakesControllerWithLocale < FakesController
+  def config_locale
+    'en'
+  end
+end
+
+describe Spree::Core::ControllerHelpers::Locale, type: :controller do
+  controller(FakesController) {}
+
+  describe '#current_locale' do
+    context 'store with local set' do
+      let!(:store) { create :store, default: true, default_locale: 'fr' }
+
+      it 'returns current store default locale' do
+        expect(controller.current_locale.to_s).to eq('fr')
+      end
+    end
+
+    context 'config_locale present' do
+      controller(FakesControllerWithLocale) {}
+
+      let!(:store) { create :store, default: true, default_locale: 'fr' }
+
+      it 'returns config_locale if present' do
+        expect(controller.current_locale.to_s).to eq('en')
+      end
+    end
+
+    context 'store without locale set' do
+      let!(:store) { create :store, default: true }
+
+      context 'without I18n.default_locale set' do
+        it 'fallbacks to english' do
+          expect(controller.current_locale.to_s).to eq('en')
+        end
+      end
+
+      context 'with I18n.default_locale set' do
+        before { I18n.default_locale = :de }
+
+        after { I18n.default_locale = :en }
+
+        it 'fallbacks to the default application locale' do
+          expect(controller.current_locale.to_s).to eq('de')
+        end
+      end
+    end
+  end
+
+  describe '#supported_locales' do
+    let!(:store) { create :store, default: true, default_locale: 'de' }
+
+    it 'returns supported currencies' do
+      expect(controller.supported_locales.to_s).to include('de')
+    end
+  end
+end