(ns transito.core
  "
  For easier transit handling...
  Caching of keywords, no transit UUID's.
  "
  (:require
    [cognitect.transit :as transit]
    [com.cognitect.transit :as t]))

(deftype ^:no-doc MapBuilder []
  Object
  (init [_ node] (transient {}))
  (add [_ m k v node] (assoc! m (keyword k) v))
  (finalize [_ m node] (persistent! m)))

(deftype ^:no-doc VectorBuilder []
  Object
  (init [_ node] (transient []))
  (add [_ v x node] (conj! v x))
  (finalize [_ v node] (persistent! v))
  (fromArray [_ arr node] (cljs.core/PersistentVector.fromArray arr true)))

(defn reader []
  (t/reader "json"
            #js{:handlers
                (clj->js
                  {"$" (fn [v] (symbol v))
                   ":" (fn [v] (keyword v))
                   "set" (fn [v] (into #{} v))
                   "list" (fn [v] (into () (.reverse v)))
                   "cmap" (fn [v]
                            (loop [i 0 ret (transient {})]
                              (if (< i (alength v))
                                (recur (+ i 2)
                                       (assoc! ret (aget v i) (aget v (inc i))))
                                (persistent! ret))))})
                :mapBuilder (MapBuilder.)
                :arrayBuilder (VectorBuilder.)
                :prefersStrings false}))

(transit/read
  (reader)
  (js/JSON.stringify (clj->js {:a "b" :c ["d" {:e "f"}]})))