module RTM::AR
  module TraverseAssociations
    def define_association(prop, options={})
      r = options[:rule]
      module_eval(<<-EOS, "(__AR_DELEGATOR_DEFINE_ASSOCIATION__)", 1)
        def direct_#{prop}_roles
          # prefetch typing topics
          rtype = @ips_#{prop}_rtype ||= self.topic_map.get("#{r[:role_type]}")
          atype = @ips_#{prop}_atype ||= self.topic_map.get("#{r[:association_type]}")
          otype = @ips_#{prop}_otype ||= self.topic_map.get("#{r[:other_role_type]}")
          # return nothing if any of the typing topics does not exist
          return [] unless rtype && atype && otype
          # we do that only here and not earlier because some might me nil
          rtype = rtype.id
          atype = atype.id
          otype = otype.id
          self.__getobj__.roles.map{|r|
            r.ttype_id != nil &&
              r.ttype_id == rtype &&
              r.parent.roles.size == #{r[:association_arity]} &&
              r.parent != nil &&
              r.parent.ttype_id == atype &&
              (r2 = r.parent.roles.select{|r2| r2.ttype_id != nil &&
                r2.ttype_id == otype}.first) &&
              r2}.select{|r2| r2}.map{|r2| AssociationRole.wrap(r2)}
        end
        def direct_#{prop}
          direct_#{prop}_roles.map{|r2| r2.player}.uniq
        end
      EOS
      
      if r[:transitive]
        module_eval(<<-EOS, "(__AR_DELEGATOR_DEFINE_ASSOCIATION2__)", 1)
          def #{prop}
            d = todo = self.direct_#{prop}
            while todo.size > 0
              todo = todo.map{|dt| dt.direct_#{prop}}.flatten.uniq - d
              d += todo
            end
            d
            #d2 = self.direct_#{prop}.map {|dt| dt.#{prop}}.flatten
            #(d+d2).uniq
          end
        EOS
      else
        if r[:infer] && r[:infer_other] # this part is not testet at all!
          module_eval(<<-EOS, "(__AR_DELEGATOR_DEFINE_ASSOCIATION3a__)", 1)
            def #{prop}
              dps = (self + self.#{r[:infer]}).flatten.uniq
              dcps = dps.map{|d2| d2.direct_#{prop}}
              (dcps + dcps.map{|d2| d2.#{r[:infer_other]}}).flatten.uniq
            end
          EOS
        elsif r[:infer]
          module_eval(<<-EOS, "(__AR_DELEGATOR_DEFINE_ASSOCIATION3__)", 1)
            def #{prop}
              (self.direct_#{prop} + self.#{r[:infer]}.map{|d2| d2.direct_#{prop}}).flatten.uniq
            end
          EOS
        elsif r[:infer_other]
          module_eval(<<-EOS, "(__AR_DELEGATOR_DEFINE_ASSOCIATION4__)", 1)
            def #{prop}
              d = self.direct_#{prop}
              (d + d.map{|d2| d2.#{r[:infer_other]}}).flatten.uniq
            end
          EOS
        end
      end
      if r[:add]
        module_eval(<<-EOS, "(__AR_DELEGATOR_DEFINE_ASSOCIATION_ADD_REMOVE__)", 1)
          def add_#{r[:add]}(t)
            a = self.topic_map.create_association("#{r[:association_type]}")
            a.create_role self, "#{r[:role_type]}"
            a.create_role t, "#{r[:other_role_type]}"
            a
            # TODO add_x in define_association needs to trigger reload of the topics somewhere
          end
          def remove_#{r[:add]}(t)
            direct_#{prop}_roles.select{|r| r.player == t}.each{|r| r.parent.remove}
            # TODO remove_x in define_association needs to trigger reload of the topics somewhere
          end
        EOS
      end
    end
  end
end