(ns t3)

(defn- which-char? [coll]
  (let [freqs (frequencies coll)
        freq  (fn [c] (get freqs c 0))]
    (cond
       (> (freq \x) (freq \0)) \0
       (< (freq \x) (freq \0)) \x
       :else (rand-nth "0x"))))

(defn- playe­r [coll­]
  "0 gets to play first ... apparently :)"
  (let [freq­s (freq­uencies coll)
       ­ freq  #(get­ freqs­ % 0)]
    (cond­ (ever­y? #{\-}­ coll)­      \0
          (>= (freq­ \x) (freq­ \0)) \0
          :else­                    \x)))

(defn play [coll]
  (let [char  (which-char? coll)
        place (fn [n] (flatten [(take n coll) char (drop (inc n) coll)]))
        free  (map first (filter #(= (second %) \-) (map-indexed vector coll)))
        free? (fn [n] (some #(= % n) free))
        evens (filter even? free)]
    (apply str (place (cond
                        (free? 4) 4
                        (seq evens) (rand-nth evens)
                        :else (rand-nth free))))))