1 files changed, 104 insertions, 0 deletions
diff --git a/lib/http_accept_language/parser.rb b/lib/http_accept_language/parser.rb
new file mode 100644
index 0000000..0aad1a2
--- /dev/null
+++ b/lib/http_accept_language/parser.rb
@@ -0,0 +1,104 @@
+module HttpAcceptLanguage
+
+  class Parser
+
+    attr_accessor :header
+
+    def initialize(header)
+      @header = header
+    end
+
+    # Returns a sorted array based on user preference in HTTP_ACCEPT_LANGUAGE.
+    # Browsers send this HTTP header, so don't think this is holy.
+    #
+    # Example:
+    #
+    #   request.user_preferred_languages
+    #   # => [ 'nl-NL', 'nl-BE', 'nl', 'en-US', 'en' ]
+    #
+    def user_preferred_languages
+      @user_preferred_languages ||= header.gsub(/\s+/, '').split(/,/).collect do |l|
+        l += ';q=1.0' unless l =~ /;q=\d+\.\d+$/
+          l.split(';q=')
+      end.sort do |x,y|
+        raise "Not correctly formatted" unless x.first =~ /^[a-z\-0-9]+$/i
+        y.last.to_f <=> x.last.to_f
+      end.collect do |l|
+        l.first.downcase.gsub(/-[a-z0-9]+$/i) { |x| x.upcase }
+      end
+    rescue # Just rescue anything if the browser messed up badly.
+      []
+    end
+
+    # Sets the user languages preference, overiding the browser
+    #
+    def user_preferred_languages=(languages)
+      @user_preferred_languages = languages
+    end
+
+    # Finds the locale specifically requested by the browser.
+    #
+    # Example:
+    #
+    #   request.preferred_language_from I18n.available_locales
+    #   # => 'nl'
+    #
+    def preferred_language_from(array)
+      (user_preferred_languages & array.collect { |i| i.to_s }).first
+    end
+
+    # Returns the first of the user_preferred_languages that is compatible
+    # with the available locales. Ignores region.
+    #
+    # Example:
+    #
+    #   request.compatible_language_from I18n.available_locales
+    #
+    def compatible_language_from(available_languages)
+      user_preferred_languages.map do |x| #en-US
+        available_languages.find do |y| # en
+          y = y.to_s
+          x == y || x.split('-', 2).first == y.split('-', 2).first
+        end
+      end.compact.first
+    end
+
+    # Returns a supplied list of available locals without any extra application info
+    # that may be attached to the locale for storage in the application.
+    #
+    # Example:
+    # [ja_JP-x1, en-US-x4, en_UK-x5, fr-FR-x3] => [ja-JP, en-US, en-UK, fr-FR]
+    #
+    def sanitize_available_locales(available_languages)
+      available_languages.map do |avail|
+        split_locale = avail.split(/[_-]/)
+
+        split_locale.map do |e|
+          e unless e.match(/x|[0-9*]/)
+        end.compact.join("-")
+      end
+    end
+
+    # Returns the first of the user preferred languages that is
+    # also found in available languages.  Finds best fit by matching on
+    # primary language first and secondarily on region.  If no matching region is
+    # found, return the first language in the group matching that primary language.
+    #
+    # Example:
+    #
+    #   request.language_region_compatible(available_languages)
+    #
+    def language_region_compatible_from(available_languages)
+      available_languages = sanitize_available_locales(available_languages)
+      user_preferred_languages.map do |x| #en-US
+        lang_group = available_languages.select do |y| # en
+          y = y.to_s
+          x.split('-', 2).first == y.split('-', 2).first
+        end
+        lang_group.find{|l| l == x} || lang_group.first #en-US, en-UK
+      end.compact.first
+    end
+
+  end
+
+end