Add experimental I18n Locale middleware

lib/rack/contrib.rb

@@ -5,11 +5,12 @@ def self.release
       "0.4"
     end
   end
-  
+
   autoload :ContentLength,              "rack/content_length"
   autoload :ETag,                       "rack/etag"
   autoload :JSONP,                      "rack/jsonp"
   autoload :LighttpdScriptNameFix,      "rack/lighttpd_script_name_fix"
+  autoload :Locale,                     "rack/locale"
   autoload :MailExceptions,             "rack/mailexceptions"
   autoload :PostBodyContentTypeParser,  "rack/post_body_content_type_parser"
   autoload :Sendfile,                   "rack/sendfile"

lib/rack/locale.rb

@@ -0,0 +1,31 @@
+require 'i18n'
+
+module Rack
+  class Locale
+    def initialize(app)
+      @app = app
+    end
+
+    def call(env)
+      old_locale = I18n.locale
+      locale = nil
+
+      # http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.4
+      if lang = env["HTTP_ACCEPT_LANGUAGE"]
+        lang = lang.split(",").map { |l|
+          l += ';q=1.0' unless l =~ /;q=\d+\.\d+$/
+          l.split(';q=')
+        }.first
+        locale = lang.first.split("-").first
+      else
+        locale = I18n.default_locale
+      end
+
+      locale = env['rack.locale'] = I18n.locale = locale.to_s
+      status, headers, body = @app.call(env)
+      headers['Content-Language'] = locale
+      I18n.locale = old_locale
+      [status, headers, body]
+    end
+  end
+end