(define-module (array3d)
  #:use-module (srfi srfi-9))

(define-record-type <array3d>
  (make-array3d packed max-voltage changed changed-recently image set)
  array3d?
  (packed array3d-packed)
  (max-voltage array3d-max-voltage set-array3d-max-voltage!)
  (changed array3d-changed set-array3d-changed!)
  (changed-recently array3d-changed-recently set-array3d-recently-changed!)
  (image array3d-image)
  (set array3d-set))

(define (array-set arr x y z p)
  (let ((img (array3d-image arr)))
    (if (array3d-packed arr)
	(let ((max-v (array3d-max-voltage arr)))
	  (when (> p max-v)
	    (set-array3d-max-voltage! arr (* 2.0 p)))
	  (if (> (array-ref img x y z) max-v)
	    (array-set! img (+ p (* 2.0 max-v)) x y z)))
	(array-set! img p x y z))
    (set-array3d-changed! arr #t)
    (set-array3d-recently-changed! arr #t)))

(define (array-new nx  ny nz packed)
  (make-array3d packed 0.0 #f #f (make-typed-array 'f64 0 nx ny nz) array-set))

(define (array-ref-by-pos array pos)
  (let* ((dimensions (array-dimensions array))
	 (nx (car dimensions))
	 (ny (cadr dimensions))
	 (z (quotient pos
		      (* nx ny)))
	 (y (quotient (- pos (* z nx ny))
		      ny))
	 (x (- pos (* z nx ny) (* y nx))))
    (array-ref array x y z)))

(let* ((dim 300)
       (packed #f)
       (arr (array-new dim dim dim packed)))
  (do ((x 0 (1+ x)))
      ((>= x dim))
    (do ((y 0 (1+ y)))
	((>= y dim))
      (do ((z 0 (1+ z)))
	  ((>= z dim))
	(array-set arr x y z (* x x)))))
  (format #t "~a ~a~%" (array-ref-by-pos (array3d-image arr) (- (expt dim 3) 1)) (expt (- dim 1) 2))
  (newline))