(ns adventofcode2019.day02
    [:require [adventofcode2019.lib :refer :all]
              [clojure.string :as str]
              [clojure.math.combinatorics :as combo]])

(def opcodes {1 +, 2 *})
(defn perform-operation [[opcode fst snd thd] program]
  (let [opcode-fn (opcodes opcode)
        fst-val (program fst)
        snd-val (program snd)]
    (assoc program thd (opcode-fn fst-val snd-val))))

(defn intcode [program]
  (loop [program program
         counter 0]
    (let [opcode (program counter)]
      (if (= opcode 99)
        program
        (recur (perform-operation (map program (take 4 (iterate inc counter)))
                                  program)
               (+ counter 4))))))

(defn check-inputs [input noun verb]
  (let [fixed-input (assoc input 1 noun 2 verb)] 
    (first (intcode fixed-input))))

(defn day02 []
  (let [input (mapv parse-int (get-list-from-file (input-file) #",")) 
        [noun verb] (first (filter (fn [[noun verb]] (= (check-inputs input noun verb) 19690720))
                                   (combo/cartesian-product (range 100) (range 100))))]
    (println (check-inputs input 12 2)) ;; part 1
    (println (+ (* 100 noun) verb)))) ;; part 2