;;;; prompt.lisp -- a function using readlline to collect text from the user

(defpackage #:oneliners.cli.prompt
  (:use #:cl)
  (:local-nicknames (#:rl #:cl-readline))
  (:export #:prompt))

(in-package :oneliners.cli.prompt)

(defun prompt (prompt
               &key
                 (expect (constantly t))
                 retry-text
                 (prefill ""))
  ;; register a prefill hook
  (rl:register-hook
   :pre-input
   (lambda ()
     (rl:insert-text prefill)
     (rl:redisplay)))
  (unwind-protect 
       (loop
         with prompt-text = prompt
         with should-retry-p = t
         while should-retry-p
         for line = (rl:readline :prompt prompt-text)
         when (funcall expect line)
           do (setf should-retry-p nil)
         when retry-text
           do (setf prompt-text retry-text)
         finally (return line))
    ;; unregisters the hook.
    (rl:register-hook :pre-input nil)))