;define points->image
(define (points->image a-size points foreground background)
  (local [(define (row->image y)
            (xs->image a-size (xs (row points y)) foreground background))]
    (apply above (map row->image (range 0 size 1)))))

;define variables
(define kat (render (scale . 1/4)))

(define (draw-all a-maze kat-point click-point)
  (align-overlay "left" "top"
                 (above (rectangle 0 (* (height barrier) (Y kat-point)) "solid" "transparent")
                        (beside (rectangle (* (width barrier) (X kat-point)) 0 "solid" "transparent")
                                kat))
                 (overlay (points->image size (path a-maze kat-point click-point) highlight invisible)
                          (points->image size a-maze invisible barrier)
                          (scale ground size))))
;in-grid?
(define (in-grid? a-point)
    (if [(< (X a-point) 0) #false]
        [(< (Y a-point) 0) #false]
        [(> (- size (X a-point))0) #true]
        [(> (- size (Y a-point))0) #true]
        [(< (X a-point) size) #true]
        [(< (Y a-point) size) #true]
        [else #false]))

;check-expect
(check-expect (in-grid? (point -1 0))
                (if [(< -1 0) #false]
        [(< 0 0) #false]
        [(> (- size -1)0) #true]
        [(> (- size 0)0) #true]
        [(< -1 size) #true]
        [(< 0 size) #true]
        [(< -1 0) #false]
        [(< 0 0) #false]
        [else #false]))