maze-generation

(require '[clojure.string :as s])

;; Maze GENERATION

(defn north-of [[row col]] [(dec row) col])
(defn south-of [[row col]] [(inc row) col])
(defn west-of  [[row col]] [row (dec col)])
(defn east-of  [[row col]] [row (inc col)])

(defn neighbours [rows cols cell]
  (filter (fn [[i j]] (and (< -1 i rows) (< -1 j cols))) ((juxt north-of east-of south-of west-of) cell)))

(defn visited? [fallen-walls rows cols cell]
  (some fallen-walls (for [n (neighbours rows cols cell)] #{n cell})))

(defn find-unvisited-neighbours [fallen-walls rows cols cell]
  (let [n (neighbours rows cols cell)]
    (remove #(visited? fallen-walls rows cols %) n)))

(defn generate-maze [rows cols]
  (loop [fallen-walls   #{}
         backtrackstack '([0 0])]
    (if-some [cell (peek backtrackstack)]
      (if-some [unvn (seq (find-unvisited-neighbours fallen-walls rows cols cell))]
        (let [next (rand-nth unvn)]
          (recur
            (conj fallen-walls #{next cell})
            (conj backtrackstack next)))
        (recur fallen-walls (pop backtrackstack)))
      {:fallen-walls fallen-walls
       :cols cols
       :rows rows})))

;; Maze PRINTING

(defn print-maze [{:keys [fallen-walls rows cols]}]
  (doseq [j (range cols)]
    (print "+---"))
  (println "+")
  (doseq [i (range rows)]
    (doseq [j (range cols)]
      (print (if (fallen-walls #{[i j] [i (dec j)]}) "    " "|   ")))
    (println "|")
    (doseq [j (range cols)]
      (print (if (fallen-walls #{[i j] [(inc i) j]}) "+   " "+---")))
    (println "+")))
    
;; Maze DRAWING

(defn draw-maze [{:keys [fallen-walls rows cols]}]
  (let [w (* 10 (inc cols))
        h (* 10 (inc rows))
        img (java.awt.image.BufferedImage. w h java.awt.image.BufferedImage/TYPE_INT_RGB)
        g (.createGraphics img)]
    (doto g
      (.translate 10 10)
      (.scale 10 10)
      (.setBackground java.awt.Color/BLACK)
      (.setColor java.awt.Color/WHITE)
      (.setStroke (java.awt.BasicStroke. 0.5))
      (.clearRect 0 0 w h))
    (doseq [[[i j] [ii jj]] (map seq fallen-walls)]
      (.drawLine g j i jj ii))
    img))