;;; password-gen.el --- Simple password generator  -*- lexical-binding: t; -*-

;; Copyright (C) 2024  Lucien Cartier-Tilet

;; Author: Lucien Cartier-Tilet <lucien@phundrak.com>
;; Maintainer: Lucien Cartier-Tilet <lucien@phundrak.com>
;; URL: https://labs.phundrak.com/phundrak/password-gen.el
;; Version: 0.1.0
;; Package-Requires: ((emacs "26.1") (transient "0.3.7"))
;; Keywords: convenience

;; This file is not part of GNU Emacs.

;; This program is free software: you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation, either version 3 of the License, or
;; (at your option) any later version.

;; This program is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;; GNU General Public License for more details.

;; You should have received a copy of the GNU General Public License
;; along with this program. If not, see <https://www.gnu.org/licenses/>.

;;; Commentary:
;;
;; Simple password generator, based on transient.
;;

;;; Code:

;;; Requires
(require 'transient)

(defconst password-gen-version "0.1.0")

(defgroup password-gen ()
  "Password generator for Emacs."
  :group 'applications
  :prefix "password-gen-"
  :link '(url-link :tag "Gitea" "https://labs.phundrak.com/phundrak/password-gen.el"))


;;; Internal Functions

(eval-when-compile
  (defmacro password-gen--define-infix (key name description type version
                                            default &rest reader)
    "Define infix and its corresponding variable at once.
The variable is named password-gen--NAME and is of type TYPE, has
a DESCRIPTION and a specified VERSION. They KEY and READER are
for the infix declaration.

This macro is largely copied from Tecosaur’s screenshot.el"
    (let ((var-name (concat "password-gen--" name)))
      `(progn
         (defcustom ,(intern var-name) ,default
           ,description
           :type ,type
           :group 'password-gen
           :version ,version)
         (transient-define-infix ,(intern (concat "password-gen--set-" name)) ()
           "Set password-gen options."
           :class 'transient-lisp-variable
           :variable ',(intern var-name)
           :key ,key
           :description ,description
           :argument ,(concat "--" name)
           :reader (lambda (&rest _) ,@reader)))))

  (password-gen--define-infix
   "-n" "numbers" "Include 0-9 numbers"
   'boolean "0.1.0" t
   (not password-gen--numbers))

  (password-gen--define-infix
   "-C" "uppercase" "Include A-Z characters"
   'boolean "0.1.0" t
   (not password-gen--uppercase))

  (password-gen--define-infix
   "-c" "lowercase" "Include a-z characters"
   'boolean "0.1.0" t
   (not password-gen--lowercase))

  (password-gen--define-infix
   "-s" "symbols" "Include !@#$%^&* symbols"
   'boolean "0.1.0" t
   (not password-gen--symbols))

  (password-gen--define-infix
   "-l" "length" "Length of the password"
   'boolean "0.1.0" 16
   (read-number "Length of the password: ")))

(defun password-gen--generate-password ()
  "Generate a password based on user preferences."
  (shell-command-to-string
   (format "tr -dc '%s%s%s%s' < /dev/urandom | head -c %d"
           (if password-gen--uppercase "A-Z" "")
           (if password-gen--lowercase "a-z" "")
           (if password-gen--numbers "0-9" "")
           (if password-gen--symbols "!@#$%^&*")
           password-gen--length)))

(defun password-gen--copy-generated-password ()
  "Generate new password and add it to kill ring."
  (kill-new (password-gen--generate-password)))

(defun password-gen--insert-generated-password ()
  "Insert at cursor a newly generated password."
  (insert (password-gen--generate-password)))


;;; Transient Actions
(eval-when-compile
  (defmacro password-gen--def-action (name description transient &rest body)
    "Create a function called from TRANSIENT.
DESCRIPTION is the docstring of the function named
password-gen--NAME, and it gets BODY as its body."
    `(defun ,(intern (concat "password-gen--action-" name)) (&optional _args)
       ,(concat description "

This function is meant to be called by a transient.")
       (interactive
        (list (transient-args ,transient)))
       ,@body))

  (password-gen--def-action
   "quit"
   "Exit password generator"
   'password-gen-main
   #'nil)

  (password-gen--def-action
   "copy"
   "Generate and copy password in kill-ring."
   'password-gen-main
   (password-gen--copy-generated-password))

  (password-gen--def-action
   "insert"
   "Generate and insert password at cursor."
   'password-gen-main
   (password-gen--insert-generated-password)))


;;; Transient Prefixes
(transient-define-prefix password-gen-main ()
  ["Options"
   (password-gen--set-length)
   (password-gen--set-uppercase)
   (password-gen--set-lowercase)
   (password-gen--set-numbers)
   (password-gen--set-symbols)]
  ["Actions"
   ("c" "Copy" password-gen--action-copy)
   ("i" "Insert" password-gen--action-insert)
   ("q" "Quit" password-gen--action-quit)]
  (interactive)
  (transient-setup 'password-gen))


;;;###autoload
(defun password-gen ()
  "Call the main transient."
  (interactive)
  (call-interactively #'password-gen-main))

(provide 'password-gen)
;;; password-gen.el ends here