require 'ai4r'

Object::instance_eval do
  
  def acts_as_cabalist(options = {})
    
    # == Set defaults ======================================================= #
    collection = options[:collection] || :all
    algorithm  = options[:algorithm]  || :id3
    # == END ================================================================ #
    
    # == Determine a classifier ============================================= #
    classifier = case algorithm
                 when :hyperpipes then Ai4r::Classifiers::Hyperpipes
                 when :ib1        then Ai4r::Classifiers::IB1
                 when :id3        then Ai4r::Classifiers::ID3
                 when :one_r      then Ai4r::Classifiers::OneR
                 when :prism      then Ai4r::Classifiers::Prism
                 when :zero_r     then Ai4r::Classifiers::ZeroR
                 else raise 'Unknown algorithm provided'
                 end
    # == END ================================================================ #
    
    # == Set classification methods ========================================= #
    get_signals_proc = Proc::new do
      options[:fields].map do |field|
        field.is_a?(Proc) ? field.call(self) : self.send(field)
      end
    end
    
    get_category_proc = Proc::new do 
      self.send(options[:category])
    end
    
    set_category_proc = Proc::new do |val| 
      self.send("#{options[:category]}=".to_sym, val)
      self
    end
    
    send(:define_method, 'get_signals'.to_sym,  &get_signals_proc)
    send(:define_method, 'get_category'.to_sym, &get_category_proc)
    send(:define_method, 'set_category'.to_sym, &set_category_proc)
    
    proc = Proc::new do
      data_items = send(collection).map do |el| 
        el.get_signals.push(el.get_category)
      end
      data_set   = Ai4r::Data::DataSet::new({ :data_items => data_items })
      classifier::new.build(data_set)
    end
    # == END ================================================================ #
    
    # == Register classifier ================================================ #
    Cabalist::Manager.register_classifier(self, proc)
    # == END ================================================================ #
    
  end
  
end