(ns question-3
  (:require [inputs]))

(def mock-input "xmul(2,4)%&mul[3,7]!@^do_not_mul(5,5)+mul(32,64]then(mul(11,8)mul(8,5))")
(def mock-input-2 "xmul(2,4)&mul[3,7]!^don't()_mul(5,5)+mul(32,64](mul(11,8)undo()?mul(8,5))")


(defn get-instructions [input]
  (->> input
       (re-seq #"(don't\(\))|(do\(\))|(mul\(\d{0,3},\d{0,3}\))")
       (map first)))

(defn parse-mul-instruction [mul-instruction]
  (let [re #"\w+\((\w+),\s*(\w+)\)"
        groups (re-matches re mul-instruction)]
    (map parse-long (rest groups))))


(defn process-in-do [xf]
  (let [prev (volatile! true)]
    (fn
      ([] (xf))
      ([result] (xf result))
      ([result input]
       (let [in-do? @prev]
         (case input
           "do()" (vreset! prev true)
           "don't()" (vreset! prev false)
           (when in-do? (xf result input))))))))


(defn question-3-a [input]
  (let [instructions (get-instructions input)
        xf (comp
             (map parse-mul-instruction)
             (filter seq?)
             (map #(apply * %)))]
    (transduce xf + 0 instructions)))

(defn question-3-b [input]
  (let [instructions (get-instructions input)
        xf (comp
             process-in-do
             (map parse-mul-instruction)
             (map #(apply * %)))
        products (sequence xf instructions)] ;; for some reason the transduce function throws an exception
    (reduce + 0 products)))


(defn -main []
  (println "Solution to question 3-a is: " (question-3-a inputs/question-3))
  (println "Solution to question 3-b is: " (question-3-b inputs/question-3)))