; A modified group-by for jsons.
; Eg. [{:id "id1" :title "uno"} {:id "id2" :title "due"}]
; to, for example, this: {:id1 {:id "id1 :title "uno"} :id2 {:id "id2" :title "due"}}

(defn group-json
  [f coll]
  (persistent!
    (reduce
     (fn [ret x]
       (let [k (keyword (f x))]
         (assoc! ret k x)))
     (transient {}) coll)))



; Get the data with cljs-ajax and update the ref-cursor.
(defn get-results
  [cursor limit skip]
  (GET MY_URL {:params {:limit limit :skip skip}
               :keywords? true
               :response-format :json
               :handler (fn [results]
                            (when-not (empty? results)
                                      (om/transact! (cursor)
                                                    (fn [curs]
                                                        (merge curs (group-json :id results))))))))




; An app state cursor and a ref cursor used by our component.
(defonce app-state
         (atom {:stuff {...} :other-stuff {...} :results {}}))

(defn results []
  (om/ref-cursor (:results (om/root-cursor app-state))))



; The Om component that renders the elements (using sablono).
(defn first-view [_ owner]
  (reify
    om/IRender
    (render [_]
            (let [xs (om/observe owner (results))]
                 (html
                   [:div {}
                    [:ul {}
                     (for [[k v] xs]
                          [:li {} (:title v)])]])))))



  ; Another component that triggers the query.
  (defn second-view [_ owner]
    (reify
      om/IRender
      (render [_]
              (html
                [:div {}
                 [:input {:ref "limit" :id "limit" :placeholder "Limit"}]
                 [:input {:ref "skip" :id "skip :placeholder "Skip}]
                 [:button {:onClick (fn [_]
                                        (let [limit (om/get-node owner "limit")
                                              skip  (om/get-node owner "skip")]
                                            (get-results results (.-value limit) (.-value skip))))
                                          "Fetch results"]
                  (om/build first-view)]))))