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(require '[clojure.string :as str])
(defn pad-input-map [in-map pad-val]
(let [ly (count in-map) lx (count (first in-map))
sy (+ 4 ly) sx (+ 4 lx)
buffer (byte-array (repeat (* sy sx) pad-val))]
(doseq [y (range 0 ly) x (range 0 lx)]
(aset-byte buffer (+ (* sx (+ 2 y)) 2 x) (get-in in-map [y x])))
(mapv vec (partition sx buffer))))
(defn get-number [in-map y x]
(map (partial get-in in-map)
[[(dec y) (dec x)] [(dec y) x] [(dec y) (inc x)]
[y (dec x)] [y x] [y (inc x)]
[(inc y) (dec x)] [(inc y) x] [(inc y) (inc x)]]))
(defn get-new-pixel [enhance-algo in-map y x]
(->> (get-number in-map y x)
(reduce #(cond-> (* 2 %1) (= 1 %2) inc) 0)
(get enhance-algo)))
(defn build-output-number-map [enhance-algo in-map]
(let [pad-val (if (pos? (first enhance-algo)) (first (first in-map)) 0)
padded-in-map (pad-input-map in-map pad-val)]
(->> (for [y (range 1 (dec (count padded-in-map)))]
(future
(mapv (partial get-new-pixel enhance-algo padded-in-map y)
(range 1 (dec (count (first padded-in-map)))))))
(mapv deref))))
(defn count-lit-pixels [in-map] ((frequencies (flatten in-map)) 1))
(let [[enhance-algo in-map]
(->> (slurp "./in")
str/split-lines
((juxt (comp (partial mapv {\. 0 \# 1}) first)
(comp (partial mapv #(mapv {\. 0 \# 1} %)) (partial drop 2)))))
image-output (iterate (partial build-output-number-map enhance-algo) in-map)]
(println "Part 1:" (count-lit-pixels (nth image-output 2)))
(println "Part 2:" (count-lit-pixels (nth image-output 50))))
(shutdown-agents)
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