Event source hack

es.clj

(def game-results {:rock {:rock :tie, :paper :lose, :scissor :win}
                   :paper {:rock :win, :paper :tie, :scissor :lose}
                   :scissor {:rock :lose, :paper :win, :scissor :tie}})

(defn create-game-command
  [{:keys [aggregate-id player move]} state]
  [{:event :game-created :game-id aggregate-id :creator player
    :state-change {:state :started :creator player}}
   {:event :move-decided :game-id aggregate-id :player player :move move
    :state-change {:move move}}])

(defn decide-move-command
  [{:keys [aggregate-id player move]} {creator :creator first-move :move}]
  (let [results-mapping {:win {:event :game-won :game-id aggregate-id :winner creator :loser player
                               :state-change {:state :finished}}
                         :lose {:event :game-won :game-id aggregate-id :winner player :loser creator
                                :state-change {:state :finished}}
                         :tie {:event :game-tie :game-id aggregate-id
                               :state-change {:state :finished}}}
        result (-> game-results first-move move)]
    [{:event :move-decided :game-id aggregate-id :player player :move move
      :state-change {:move move}}
     (result results-mapping)]))

defn apply-events [events state]
  (reduce merge  state (map :state-change events)))