;; from Rosetta code, with modifications https://rosettacode.org/wiki/Password_generator#Common_Lisp
(defpackage :fwoar.password-gen
  (:use :cl )
  (:export ))
(in-package :fwoar.password-gen)

(defparameter *lowercase*
  '(#\a #\b #\c #\d #\e #\f #\g #\h #\i #\j #\k #\l #\m #\n #\o #\p
    #\q #\r #\s #\t #\u #\v #\w #\x #\y #\z))

(defparameter *uppercase*
  '(#\A #\B #\C #\D #\E #\F #\G #\H #\I #\J #\K #\L #\M #\N #\O #\P
    #\Q #\R #\S #\T #\U #\V #\W #\X #\Y #\Z))

(defparameter *numbers*
  '(#\0 #\1 #\2 #\3 #\4 #\5 #\6 #\7 #\8 #\9))

(defparameter *special-characters*
  '(#\! #\\ #\# #\% #\& #\* #\+ #\, #\- #\. #\: #\< #\= #\>
    #\? #\^ #\_ #\| #\~))

(defparameter *similar-characters*
  '(#\I #\l #\1 #\| #\O #\0 #\5 #\S #\2 #\Z))

(defun make-readable (s)
  (remove-if (lambda (x) (member x *similar-characters*)) s))

(defun shuffle-list (input-list)
  (loop with l = (length input-list)
        for i below l
        do (rotatef (nth i input-list)
                    (nth (random l) input-list)))
  input-list)

(defun generate-password (len human-readable)
  (let*
      ((upper (if human-readable (make-readable *uppercase*) *uppercase*))
       (lower (if human-readable (make-readable *lowercase*) *lowercase*))
       (number (if human-readable (make-readable *numbers*) *numbers*))
       (special (if human-readable (make-readable *special-characters*) *special-characters*))
       (character-groups (list upper lower number special))
       (initial-password (reduce (lambda (acc x)
                                   (cons (nth (random (length x)) x) acc))
                                 character-groups :initial-value NIL)))
    
    (coerce (shuffle-list (reduce (lambda (acc x)
                                    (declare (ignore x))
                                    (let ((group (nth (random (length character-groups)) character-groups)))
                                      (cons (nth (random (length group)) group) acc)))
                                  (make-list (- len 4)) :initial-value initial-password)) 'string)))

(defun main (len count &optional human-readable)
  (if (< len 4)
      (print "Length must be at least 4~%")
      (loop for x from 1 to count do
        (princ (generate-password len human-readable))
        (terpri))))