mars-rovers-boundaries.clj

(ns mars-rovers.core)

(def dirs [:N :E :S :W])

(def move-dir {:N [0, 1] :E [1, 0] :S [0, -1] :W [-1, 0]})

(defn turn [dir dirs]
  (second
    (drop-while
      (complement #(= % dir))
      (cycle dirs))))

(defn turn-left [dir]
  (turn dir (reverse dirs)))

(defn turn-right [dir]
  (turn dir dirs))

(defn move [x y dir]
  (conj
    (vec
      (map + [x y]
           (move-dir dir)))
    dir))

(defn check-position [[[x y] [max-x max-y] :as all]]
  (if (and (<= 0 x max-x) (<= 0 y max-y))
    all
    (throw (java.lang.IllegalArgumentException.
             (str "Rover fall of the plateau at: " x \space y)))))

(defn rover-action [[[x y dir] [max-x max-y]] action]
  (check-position 
    [(cond
       (= action \L) [x y (turn-left dir)]
       (= action \R) [x y (turn-right dir)]
       (= action \M) (move x y dir))
     [max-x
      max-y]]))

(defn deploy-rover [start bounds path]
  (reduce rover-action [start bounds] path))