Merge pull request #1058 from rughh/feat/detect_browser_locale

feat: detect browser locale

Author: salzig

app/controllers/concerns/locale_detection.rb

@@ -4,7 +4,7 @@ module LocaleDetection
   protected
 
   def switch_locale
-    locale = params[:locale] || cookies[:locale]
+    locale = params[:locale] || cookies[:locale] || available_accepted_locales
     I18n.locale = allowed_locale?(locale) ? locale : default_locale
 
     cookies[:locale] = {
@@ -21,4 +21,23 @@ def allowed_locale?(locale)
   def default_locale
     Whitelabel.label ? Whitelabel[:default_locale] : I18n.default_locale
   end
+
+  def available_accepted_locales
+    (accepted_locales & I18n.available_locales).first
+  end
+
+  def accepted_locales
+    locales = parsed_accepted_locales.sort_by(&:last).reverse
+    locales.map(&:first)
+  end
+
+  def parsed_accepted_locales
+    accepted_locales = request.env['HTTP_ACCEPT_LANGUAGE']&.split(',')
+    return [] unless accepted_locales
+
+    accepted_locales.map do |prefered_locale|
+      locale, quality = prefered_locale.strip.split(/;(?:q=)/)
+      [locale.strip.to_sym, quality&.to_f || 1.0]
+    end
+  end
 end

spec/controllers/concerns/locale_detection_spec.rb

@@ -0,0 +1,53 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe LocaleDetection do
+  controller(ApplicationController) do
+    def index
+      head :ok
+    end
+  end
+
+  before do
+    routes.draw { get 'index' => 'anonymous#index' }
+  end
+
+  it 'concern is included' do
+    expect(controller.class.ancestors.include?(described_class)).to be(true)
+  end
+
+  it 'uses the default locale if no locale is requested and browser doesnt provide locales' do
+    get :index
+    expect(I18n.locale).to eq(I18n.default_locale)
+  end
+
+  it 'uses the defaut locale if the browser provided ones arent available' do
+    request.headers.merge! 'Accept-Language': 'fr-CH, fr;q=0.9, *;q=0.5'
+    get :index
+    expect(I18n.locale).to eq(I18n.default_locale)
+  end
+
+  it 'uses the default locale if the requested locale is not available' do
+    get :index, params: { locale: 'yy' }
+    expect(I18n.locale).to eq(I18n.default_locale)
+  end
+
+  it 'uses first matching locale from browser provided list' do
+    request.headers.merge! 'Accept-Language': 'pl-PL, pl;q=0.9, en;q=0.8, *;q=0.5'
+    get :index
+    expect(I18n.locale).to eq(:pl)
+  end
+
+  it 'switches the locale via params' do
+    get :index, params: { locale: 'de' }
+    expect(I18n.locale).to eq(:de)
+    expect(cookies[:locale]).to eq('de')
+  end
+
+  it 'uses the locale from a cookie' do
+    cookies[:locale] = 'pl'
+    get :index
+    expect(I18n.locale).to eq(:pl)
+  end
+end