;;; epa-file.el --- the EasyPG Assistant hooks for transparent file encryption
;; Copyright (C) 2006 Daiki Ueno

;; Author: Daiki Ueno <ueno@unixuser.org>
;; Keywords: PGP, GnuPG

;; This file is part of EasyPG.

;; 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 2, 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 GNU Emacs; see the file COPYING.  If not, write to the
;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
;; Boston, MA 02110-1301, USA.

;;; Code:

(require 'epa)

(defgroup epa-file nil
  "The EasyPG Assistant hooks for transparent file encryption"
  :group 'epa)

(defcustom epa-file-name-regexp "\\.gpg\\'"
  "Regexp which matches filenames to be encrypted with GnuPG."
  :type 'regexp
  :group 'epa-file)
  
(defvar epa-file nil)

(defun epa-find-file ()
  (when (string-match epa-file-name-regexp (buffer-file-name))
    (if (= (buffer-size) 0)
	(progn
	  (set-auto-mode)
	  (hack-local-variables)
	  (auto-save-mode nil))
      (goto-char (point-min))
      (insert (epg-decrypt-file (epg-make-context)
				(expand-file-name (buffer-file-name))
				nil))
      (delete-region (point) (point-max))
      (decode-coding-region (point-min) (point-max) 'undecided))
    (make-local-variable 'epa-file)
    (setq epa-file (buffer-file-name))))

(defun epa-write-file ()
  (when epa-file
    (write-region
     (epg-encrypt-string
      (epg-make-context)
      (buffer-string)
      (mapcar (lambda (key)
		(epg-sub-key-id
		 (car (epg-key-sub-key-list key))))
	      (epa-select-keys
		 "Select recipents for encryption.
If no one is selected, symmetric encryption will be performed.  ")))
     nil (expand-file-name (buffer-file-name)))
    (set-buffer-modified-p nil)
    t))

(provide 'epa-file)

;;; epa-file.el ends here