;;#!/usr/bin/sbcl --script

(defvar *randomness* (make-random-state t))

(defun split-string (string delimiter)
  (loop with len = (length string)
        with start = 0
        for end = (position delimiter string :start start)
        for substr = (if end
                        (subseq string start end)
                        (subseq string start))
        while end
        append (list substr)
        do (setf start (1+ end))
        until (= end len)))

(defun list-files-in-directory (directory-path)
  (let* ((files (directory (merge-pathnames "*.*" (pathname directory-path))))
         (directory-pathname (pathname directory-path)))
    (mapcar #'(lambda (file)
                (merge-pathnames (pathname file) directory-pathname))
            files)))

(defun bins-list ()
  (apply #'append
	 (mapcar #'list-files-in-directory
		 (loop for path in (split-string (sb-ext:posix-getenv "PATH") #\:)
		       collect (format NIL "~a~c" path #\/)))))

(defun random-bin (bins-list)
  (namestring (nth (random (length bins-list) *randomness*) bins-list)))

(defun random-cmd (bins-list)
  (let ((number-of-pipes (random 4 *randomness*))
	(cmd-str ""))
    (if (> number-of-pipes 0)
	(progn
	  (dotimes (i (+ 1 number-of-pipes))
	    (setq cmd-str (concatenate 'string cmd-str (format NIL "~A | " (random-bin bins-list)))))
	  (setq cmd-str (concatenate 'string (subseq cmd-str 0 (- (length cmd-str) 3)) (format NIL "~%"))))
	(setq cmd-str (concatenate 'string cmd-str (format NIL "~A~%" (random-bin bins-list)))))
    cmd-str))
  
(format T "~a" (random-cmd (bins-list)))