;; This file 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.
;;
;; To use this as the fcc handler for message-mode,
;; customize the notmuch-fcc-dirs variable

(require 'message)

(defvar notmuch-maildir-fcc-count 0)

(defcustom notmuch-fcc-dirs nil
 "Determines the maildir directory to save outgoing mails in.

 If set to non-nil, this will cause message mode to file your
 mail in the specified directory (fcc).

 It is either a string if you only need one fcc directory or a
 list if they depend on your From address (see example).

 In the former case it is a string such as \"INBOX.Sent\".

 In the fancy setup, where you want different outboxes depending
 on your From address, you supply a list like this:

     ((\"defaultinbox\")
      (\"Sebastian Spaeth <Sebastian@SSpaeth.de>\" . \"privat\")
      (\"Sebastian Spaeth <spaetz@sspaeth.de>\" . \"OUTBOX.OSS\")
     )

 The outbox that matches a key (case insensitive) will be
 used. The first entry is used as a default fallback when nothing
 else matches.

 In all cases, the complete FCC directory will be constructed by 
 concatenating the content  of the variable 'message-directory' 
 ('~/Mail/' by default and customizable via M-x
 customize-variable<RET>message-directory<RET>) and this value.

 You will be prompted to create the directory if it does not exist yet when 
 sending a mail.

 This function will not modify the headers if there is a FCC
 header, but will check that the target directory exists."

 :require 'notmuch-fcc-initialization
 :group 'notmuch
)

(defun notmuch-fcc-initialization ()
  "If notmuch-fcc-directories is set,
   hook them into the message-fcc-handler-function"
    ;; Set up the message-fcc-handler to move mails to the maildir in Fcc
    ;; The parameter is set to mark messages as "seen"
    (setq message-fcc-handler-function
          '(lambda (destdir)
             (notmuch-maildir-fcc-write-buffer-to-maildir destdir t)))
    ;;add a hook to actually insert the Fcc header when sending
    (add-hook 'message-send-hook 'notmuch-fcc-header-setup))

(defun notmuch-fcc-header-setup ()
  "Adds an appropriate fcc header to the current mail buffer

   Can be added to message-send-hook and will set the FCC header
   based on the values of notmuch-fcc-directories (see the
   variable customization there for examples). It uses the first
   entry as default fallback if no From address matches."
  ;; only do something if notmuch-fcc-dirs is set
  (when notmuch-fcc-dirs
    (let (subdir)
      (if (stringp notmuch-fcc-dirs)
          ;; notmuch-fcc-dirs is a string, just use it as subdir
          (setq subdir notmuch-fcc-dirs)
        ;; else: it's a list of alists (("sent") ("name1" . "sent1"))
        (setq subdir (cdr (assoc-string (message-fetch-field "from") notmuch-fcc-dirs t)))
         ;; if we found no hit, use the first entry as default fallback
         (unless subdir (setq subdir (car (car notmuch-fcc-dirs)))))

  ;; if there is no fcc header yet, add ours
  (unless (message-fetch-field "fcc")
    (message-add-header (concat "Fcc: "
                                (file-name-as-directory message-directory)
                                subdir)))

  ;; finally test if fcc points to a valid maildir
  (let ((fcc-header (message-fetch-field "fcc")))
    (unless (notmuch-maildir-fcc-dir-is-maildir-p fcc-header)
      (cond ((not (file-writable-p fcc-header))
             (error (format "%s is not a maildir, but you don't have permission to create one." fcc-header)))
            ((y-or-n-p (format "%s is not a maildir. Create it? "
                               fcc-header))
             (notmuch-maildir-fcc-create-maildir fcc-header))
            (t
             (error "Not sending message."))))))))
 
(defun notmuch-maildir-fcc-host-fixer (hostname)
  (replace-regexp-in-string "/\\|:"
			    '(lambda (s)
                               (cond ((string-equal s "/") "\\057")
                                     ((string-equal s ":") "\\072")
                                     (t s)))
			    hostname
			    t
			    t))

(defun notmuch-maildir-fcc-make-uniq-maildir-id ()
   (let* ((ct (current-time))
	  (timeid (+ (* (car ct) 65536) (cadr ct)))
	  (microseconds (car (cdr (cdr ct))))
	  (hostname (notmuch-maildir-fcc-host-fixer system-name)))
     (setq notmuch-maildir-fcc-count (+ notmuch-maildir-fcc-count 1))
     (format "%d.%d_%d_%d.%s"
	     timeid
	     (emacs-pid)
	     microseconds
	     notmuch-maildir-fcc-count
	     hostname)))

(defun notmuch-maildir-fcc-dir-is-maildir-p (dir)
  (and (file-exists-p (concat dir "/cur/"))
       (file-exists-p (concat dir "/new/"))
       (file-exists-p (concat dir "/tmp/"))))

(defun notmuch-maildir-fcc-create-maildir (path)
  (cond ((or (not (file-exists-p path)) (file-directory-p path))
	 (make-directory (concat path "/cur/") t)
	 (make-directory (concat path "/new/") t)
	 (make-directory (concat path "/tmp/") t))
	((file-regular-p path)
	 (error "%s is a file. Can't creat maildir." path))
	(t
	 (error "I don't know how to create a maildir here"))))

(defun notmuch-maildir-fcc-save-buffer-to-tmp (destdir)
  "Returns the msg id of the message written to the temp directory
if successful, nil if not."
  (let ((msg-id (notmuch-maildir-fcc-make-uniq-maildir-id)))
    (while (file-exists-p (concat destdir "/tmp/" msg-id))
      (setq msg-id (notmuch-maildir-fcc-make-uniq-maildir-id)))
    (cond ((notmuch-maildir-fcc-dir-is-maildir-p destdir)
	   (write-file (concat destdir "/tmp/" msg-id))
	   msg-id)
	  (t
	   (error (format "Can't write to %s. Not a maildir."
			  destdir))
	   nil))))

(defun notmuch-maildir-fcc-move-tmp-to-new (destdir msg-id)
  (add-name-to-file
   (concat destdir "/tmp/" msg-id)
   (concat destdir "/new/" msg-id ":2,")))

(defun notmuch-maildir-fcc-move-tmp-to-cur (destdir msg-id &optional mark-seen)
  (add-name-to-file
   (concat destdir "/tmp/" msg-id)
   (concat destdir "/cur/" msg-id ":2," (when mark-seen "S"))))

(defun notmuch-maildir-fcc-write-buffer-to-maildir (destdir &optional mark-seen)
  "Writes the current buffer to maildir destdir. If mark-seen is
non-nil, it will write it to cur/, and mark it as read. It should
return t if successful, and nil otherwise."
  (let ((orig-buffer (buffer-name)))
    (with-temp-buffer
      (insert-buffer-substring orig-buffer)
      (catch 'link-error
	(let ((msg-id (notmuch-maildir-fcc-save-buffer-to-tmp destdir)))
	  (when msg-id
	    (cond (mark-seen
		   (condition-case err
		       (notmuch-maildir-fcc-move-tmp-to-cur destdir msg-id t)
		     (file-already-exists
		      (throw 'link-error nil))))
		  (t
		   (condition-case err
		       (notmuch-maildir-fcc-move-tmp-to-new destdir msg-id)
		     (file-already-exists
		      (throw 'link-error nil))))))
	  (delete-file (concat destdir "/tmp/" msg-id))))
      t)))

(notmuch-fcc-initialization)
(provide 'notmuch-maildir-fcc)