Actually set I18n.locale based on http header

.rspec

@@ -0,0 +1 @@
+--color

README.md

@@ -1,9 +1,12 @@
 # Locale Detector
 
-This Rails gem makes use of the HTTP_ACCEPT_LANGUAGE http header send by web browsers with every request, to set the `I18n.locale` variable.
-When this fails (for example if there is no such http header as is the case for Google bot), it will try to determine the locale based on the toplevel domain suffix (so it will set 'de' for the `example.de` domain).
+This Rails gem makes use of the HTTP_ACCEPT_LANGUAGE http header sent by web browsers with every request, to set the `I18n.locale` setting.
+When this fails (for example if there is no such http header - as is the case for Google bot), it will try to determine the locale based on the toplevel domain suffix (so it will set 'de' for the `example.de` domain).
 When both fail, it will fall back to the `LocaleDetector.fallback_locale`, which is 'en' by default and can be overriden in `config/initializers/locale_detector.rb`.
 
+The HTTP_ACCEPT_LANGUAGE header parser is based on:
+https://github.com/iain/http_accept_language/blob/master/lib/http_accept_language.rb
+
 
 ## Installation
 

lib/locale_detector/filter.rb

@@ -9,7 +9,17 @@ module Filter
     protected
 
     def set_locale
-      I18n.locale = 'en'
+      I18n.locale = begin
+        request.env['HTTP_ACCEPT_LANGUAGE'].split(/\s*,\s*/).collect do |l|
+          l += ';q=1.0' unless l =~ /;q=\d+\.\d+$/
+          l.split(';q=')
+        end.sort do |x,y|
+          raise "Incorrect format" unless x.first =~ /^[a-z\-]+$/i
+          y.last.to_f <=> x.last.to_f
+        end.first.first.gsub(/-[a-z]+$/i, '').downcase
+      rescue # rescue (anything) from the malformed (or missing) accept language headers
+        LocaleDetector.fallback_locale
+      end
     end
   end
 end

locale_detector.gemspec

@@ -21,4 +21,8 @@ Gem::Specification.new do |s|
 
   s.add_dependency 'rails', ['>= 3.0.0']
   s.add_dependency 'i18n', ['>= 0.5.0']
+  s.add_development_dependency 'guard', ['>= 0.5.0']
+  s.add_development_dependency 'guard-rspec', ['>= 0.4.0']
+  s.add_development_dependency 'rspec', ['>= 2.6']
+  s.add_development_dependency 'rspec-rails', ['>= 2.6']
 end

spec/locale_detector/fallback_locale_spec.rb

@@ -0,0 +1,9 @@
+require 'spec_helper'
+
+describe LocaleDetector do
+
+  subject { LocaleDetector.fallback_locale }
+
+  it { should_not be_empty }
+
+end

spec/locale_detector/filter_spec.rb

@@ -0,0 +1,24 @@
+require 'spec_helper'
+
+describe LocaleDetector::Filter do
+
+  def set_locale(opts = {})
+    filter = Object.new.extend(LocaleDetector::Filter)
+    request = double('request', :env => { 'HTTP_ACCEPT_LANGUAGE' => opts[:language] })
+    filter.stub(:request).and_return(request)
+    filter.send(:set_locale)
+  end
+
+  specify { set_locale(:language => nil).should eql(LocaleDetector.fallback_locale) }
+
+  specify { set_locale(:language => 'pl').should eql('pl') }
+
+  specify { set_locale(:language => 'pl-PL').should eql('pl') }
+
+  specify { set_locale(:language => 'pl,en-us;q=0.7,en;q=0.3').should eql('pl') }
+
+  specify { set_locale(:language => 'lt,en-us;q=0.8,en;q=0.6,ru;q=0.4,pl;q=0.2').should eql('lt') }
+
+  specify { set_locale(:language => 'pl-PL;q=0.1,en-us;q=0.7,en;q=0.3').should eql('en') }
+
+end

spec/spec_helper.rb

@@ -0,0 +1,9 @@
+$:.unshift(File.join(File.dirname(__FILE__), '..', 'lib'))
+$:.unshift(File.dirname(__FILE__))
+
+require 'rails'
+require 'locale_detector'
+
+RSpec.configure do |config|
+  config.mock_with :rspec
+end