# encoding: utf-8
#
module CharacterSubstitution
  # Substitutes Umlauts like
  # ä, ö, ü => ae, oe, ue.
  # (and more, see specs)
  #
  class European
    
    def initialize
      @chars = ActiveSupport::Multibyte.proxy_class
    end
    
    def substitute text
      trans = @chars.new(text).normalize(:kd)
      
      # substitute special cases
      #
      trans.gsub!('ß', 'ss')
      
      # substitute umlauts (of A,O,U,a,o,u)
      #
      trans.gsub!(/([AOUaou])\314\210/u, '\1e')
      
      # get rid of ecutes, graves and …
      #
      trans.unpack('U*').select { |cp|
        cp < 0x0300 || cp > 0x035F
      }.pack('U*')
    end
    
  end
end