(require :uiop)

(defun split-instruction (s)
  "Splits the given instruction into a pair"
  (cons (subseq s 0 1)
        (subseq s 1)))

(defun turn-dial (dial instruction)
  (let ((cons-instruction (split-instruction instruction)))
    (let ((op (intern (car cons-instruction)))
      (amount (parse-integer (cdr cons-instruction))))
        (mod
          (funcall
            (cond
              ((eql 'L op) #'-)
              ((eql 'R op) #'+)
              (t (error "unknown op")))
            dial amount)
          100)
      )
    ))

;; (turn-dial 50 "L68")
;; (turn-dial 82 "L30")
;; (turn-dial 52 "R48")

(defun rec-dial-vm (accum dial lines)
  (let ((instruction (pop lines)))
    (if instruction
      (let ((new-dial (turn-dial dial instruction)))
        (if (= new-dial 0)
          (rec-dial-vm accum new-dial lines)
          (rec-dial-vm (+ 1 accum) new-dial lines)))
      accum)))

(rec-dial-vm 0 50 (uiop:read-file-lines "01example.txt"))
(rec-dial-vm 0 50 (uiop:read-file-lines "01data.txt"))