(s/def :message/event #{"create" "delete" "update"})
(s/def :message/type  #{::user ::field ::new-day
                        ::planting ::fertilizing ::rainfall})
(s/def :message/timestamp int?)

(s/def ::event (s/tuple :message/event :message/type ::date))

(s/def ::message
  (s/with-gen (s/keys :req [:message/event :message/type :message/data :message/timestamp])
    #(gen/fmap (fn [[event domain-type date]]
                 (hash-map :message/event event
                           :message/type domain-type
                           :message/timestamp (.getTime date)
                           :message/data (generate-data date [domain-type event])))
               (s/gen ::event))))