(defmacro create-probe(name &body code)
  `(progn (defun ,name(params) ,@code)))

(defun command-return-code(command)
  (let ((code (nth-value 2 (uiop:run-program command :ignore-error-status t))))
    (if (= 0 code)
	t
	(list nil (format nil "return code = ~a" code)))))

(create-probe
 file-exists
 (let ((result (probe-file (getf params :path))))
   (if result
       t
       (list nil "file not found"))))

(create-probe
 file-updated
 (if (probe-file (getf params :path))
     (with-open-file (file (getf params :path))
       (let* ((write-date (file-write-date file))
	      (now (get-universal-time))
	      (result (floor (- now write-date) 60)))
	 (if (> (getf params :limit) result)
	     t
	     (list nil result))))
     (list nil "file not found")))

(create-probe
 pid-running
 (if (probe-file (getf params :path))
     (let ((pid-number (with-open-file (stream (getf params :path)) (read-line stream))))
       (command-return-code (list "ps" "-p" pid-number)))
     (list nil "file not found")))

(create-probe
 disk-usage
 (let* ((output (uiop:run-program (list "df" (getf params :path)) :output :lines)) (line (second output)))
   (let ((percent-character-pos (position #\% line)))
     (let ((used-disk
	    (parse-integer
	     (subseq line
		     (position #\Space line :end percent-character-pos :from-end t)
		     percent-character-pos))))
       (if (< used-disk (getf params :limit))
	   t
	   (list nil "used-disk"))))))

(defun system-load(time)
  (read-from-string
   (let ((command (concatenate 'string
			       "uptime | awk '{ print $"
			       (princ-to-string time)
			       " }'")))
     (uiop:run-program command :output :string))))
    
(create-probe
 load-average-1
 (let ((load (system-load 10)))
   (if (< load (getf params :limit))
       t
       (list nil load))))

(create-probe
 load-average-5
 (let ((load (system-load 11)))
   (if (< load (getf params :limit))
       t
       (list nil load))))
 
(create-probe
 load-average-15
 (let ((load (system-load 12)))
   (if (< load (getf params :limit))
       t
       (list nil load))))

(create-probe
 command
 (command-return-code (getf params :command)))

(create-probe
 ping
 (command-return-code (list "ping" "-c2" (getf params :host))))

(create-probe
 number-of-processes
 (let* ((output (uiop:run-program (list "ps" "aux") :output :lines))
	(result (length output)))
   (if (> (getf params :limit) result)
       t
       (list nil result))))