(ns day10
  (:require [mapped-area]
            [helpers :refer [get-input]]))

(def test-map
"89010123
78121874
87430965
96549874
45678903
32019012
01329801
10456732")

;(def test-map
;"0123
;1234
;8765
;9876")

(def input
  (->
   test-map
   mapped-area/read-mapped-area
   mapped-area/parse-elements))

(defn trailheads [a]
  (reduce
   (fn [coll [coord value]]
     (if (= value 0)
       (conj coll coord)
       coll))
   []
   (mapped-area/mapped-area-indexed-seq a)))

(defn step [a [x y]]
  (let [c (get-in a [x y])
        even-gradual-uphill?
        (fn [[x' y']]
          (let [c' (get-in a [x' y'])]
            (= 1 (- c' c))))]
      (->>
       [[(inc x) y] [(dec x) y]
        [x (inc y)] [x (dec y)]]
       (filter (partial mapped-area/mapped? a))
       (filter even-gradual-uphill?))))

(defn walk [a trailhead]
  (loop [positions [trailhead]]
    (println positions)
    (if (== 9 (get-in a (first positions)))
      (count positions)
      (recur (mapcat (partial step a) (set positions))))))

(loop [i 0 positions (trailheads input)]
  (println "iteration" i)
  (doall
   (map #(println % "-" (get-in input %)) positions))
  (if (== i 9)
    positions
    (recur (inc i)
            (mapcat (partial step input) positions))))

(trailheads input)

(mapcat (partial step input) (trailheads input))