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(require '[clojure.string :as str])
(require '[clojure.set :as set])
(def hex-lookup
{\0 "0000" \1 "0001" \2 "0010" \3 "0011"
\4 "0100" \5 "0101" \6 "0110" \7 "0111"
\8 "1000" \9 "1001" \A "1010" \B "1011"
\C "1100" \D "1101" \E "1110" \F "1111"})
(defn binary-to-num [binstr]
(reduce
#(cond-> %1 true (* 2) (= \1 %2) inc)
0
binstr))
(defn take-packet-version [packet]
(-> (split-at 3 packet)
(update 0 binary-to-num)))
(defn take-literal-value [packet]
(let [[tid data] (split-at 3 packet)]
(when (= '(\1 \0 \0) tid)
(let [sd (into [] data)
spl (split-with #(= \1 (first %)) (partition 5 sd))
nums (map rest (concat (first spl) (take 1 (second spl))))]
[(binary-to-num (reduce concat nums))
(drop (* 5 (inc (count (first spl)))) sd)]
))))
(defn take-operator [packet]
(let [id (first packet) ps (str/join (rest packet))]
(if (= \0 id)
(let [bits (binary-to-num (subs ps 0 15))]
[(subs ps 15) bits :bits])
(let [pkts (binary-to-num (subs ps 0 11))]
[(subs ps 11) pkts :pkts]))))
(defn process-packet [[input vcnt]]
(let [[version data] (take-packet-version input)]
(if (every? #(= \0 %) data)
['() vcnt]
(do
(if-let [value (take-literal-value data)]
[(second value) (+ vcnt version)]
(do
(let [info (take-operator (drop 3 data))]
(if (= :bits (get info 2))
(loop [inpt [(subs (first info) 0 (get info 1)) (+ vcnt version)]]
(if (empty? (first inpt))
[(subs (first info) (get info 1)) (second inpt)]
(recur (process-packet inpt))))
(loop [n (get info 1) inpt [(get info 0) (+ vcnt version)]]
(if (pos? n)
(recur (dec n) (process-packet inpt))
inpt))))))))))
(loop [packet (->> (slurp "./in")
(map hex-lookup)
(take-while some?)
(reduce concat)
(str/join)
(#(vector % 0))
(process-packet))]
(if (not (empty? (first packet)))
(recur (process-packet packet))
(println (second packet))))
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