;;; mh-mime --- mh-e support for composing MIME messages
;; Time-stamp: <94/03/08 08:41:27 gildea>

;; Copyright 1993 Free Software Foundation, Inc.

;; This file is part of mh-e.

;; mh-e 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.

;; mh-e 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 mh-e; see the file COPYING.  If not, write to
;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.

;;; Commentary:

;;; Internal support for mh-e package.
;;; Support for generating an mhn composition file.
;;; MIME is supported only by MH 6.8 or later.

;;; Code:

(provide 'mh-mime)
(require 'mh-comp)


;; To do:
;; paragraph code should not fill # lines if MIME enabled.
;; implement mh-auto-edit-mhn (if non-nil, \\[mh-send-letter]
;;	invokes mh-edit-mhn automatically before sending.)
;;      actually, instead of mh-auto-edit-mhn,
;;      should read automhnproc from profile
;; MIME option to mh-forward
;; command to move to content-description insertion point

(defvar mh-mime-content-types
  '(("text/plain") ("text/richtext")
    ("multipart/mixed") ("multipart/alternative") ("multipart/digest")
    ("multipart/parallel")
    ("message/rfc822") ("message/partial") ("message/external-body")
    ("application/octet-stream") ("application/postscript")
    ("image/jpeg") ("image/gif")
    ("audio/basic")
    ("video/mpeg"))
  "Legal MIME content types.")

(defun mh-mhn-compose-insertion (pathname type description)
  "Add a directive to insert a message part from a file.
This is the typical way to insert non-text parts in a message.
See also \\[mh-edit-mhn]."
  (interactive (list
		(read-file-name "Insert contents of: ")
		(completing-read "Content-type: "
				 mh-mime-content-types nil nil nil)
		(read-string "Content-description: ")))
  (mh-mhn-compose-type pathname type description))

(defun mh-mhn-compose-type (pathname type
			    &optional description attributes comment)
  (beginning-of-line)
  (insert "#" type)
  (and attributes
       (insert "; " attributes))
  (and comment
       (insert " (" comment ")"))
  (insert " [")
  (and description
       (insert description))
  (insert "] " (expand-file-name pathname))
  (insert "\n"))


(defun mh-mhn-compose-anon-ftp (host pathname type description)
  "Add a directive for an anonymous ftp external body part.
This directive tells MH to include a reference to a message/external-body part
retrievable by anonymous FTP.  See also \\[mh-edit-mhn]."
  (interactive (list
		(read-string "Remote host: ")
		(read-string "Remote pathname: ")
		(completing-read "External Content-type: "
				 mh-mime-content-types nil nil nil)
		(read-string "External Content-description: ")))
  (mh-mhn-compose-external-type "anon-ftp" host pathname
				type description))

(defun mh-mhn-compose-external-compressed-tar (host pathname description)
  "Add a directive to include a reference to a compressed tar file.
The file should be available via anonymous ftp.
This directive tells MH to include a reference to a message/external-body part.
See also \\[mh-edit-mhn]."
  (interactive (list
		(read-string "Remote host: ")
		(read-string "Remote pathname: ")
		(read-string "Tar file Content-description: ")))
  (mh-mhn-compose-external-type "anon-ftp" host pathname
				"application/octet-stream"
				description
				"type=tar; conversions=x-compress"
				"mode=image"))


(defun mh-mhn-compose-external-type (access-type host pathname type
				     &optional description
				     attributes extra-params comment)
  (beginning-of-line)
  (insert "#@" type)
  (and attributes
       (insert "; " attributes))
  (and comment
       (insert " (" comment ") "))
  (insert " [")
  (and description
       (insert description))
  (insert "] ")
  (insert "access-type=" access-type "; ")
  (insert "site=" host)
  (insert "; name=" (file-name-nondirectory pathname))
  (insert "; directory=\"" (file-name-directory pathname) "\"")
  (and extra-params
       (insert "; " extra-params))
  (insert "\n"))

(defun mh-mhn-compose-forw (&optional description msgs folder)
  "Add a forw directive to this message.
This directive tells MH to include the named messages in this one.
Arguments are DESCRIPTION, a line of text for the Content-description header,
MESSAGES and FOLDER, which name the message(s) to be forwarded.
See also \\[mh-edit-mhn]."
  (interactive (list
		(read-string "Forw Content-description: ")
		(read-string (format "Messages%s: "
				     (if mh-sent-from-msg
					 (format " [%d]" mh-sent-from-msg)
				       "")))
		(mh-prompt-for-folder "Message from" mh-sent-from-folder nil)))
  (beginning-of-line)
  (insert "#forw [")
  (and description
       (not (string= description ""))
       (insert description))
  (insert "]")
  (and folder
       (not (string= folder ""))
       (insert " " folder))
  (if (and msgs
	   (not (string= msgs "")))
      (let ((start (point)))
	(insert " " msgs)
	(subst-char-in-region start (point) ?, ? ))
    (if mh-sent-from-msg
	(insert " " (int-to-string mh-sent-from-msg))))
  (insert "\n"))

(defun mh-edit-mhn ()
  "Filter the current draft through the mhn program for MIME formatting.
Using directives already inserted in the draft, fills in
all the MIME components and header fields.
This step should be done last just before sending the message.
The mhn program is part of MH version 6.8 or later.
The `\\[mh-revert-mhn-edit]' command undoes this command.
For assistance with creating MIME directives to insert
various types of components in a message, see
\\[mh-mhn-compose-insertion] (generic insertion from a file),
\\[mh-mhn-compose-anon-ftp] (external reference to file via anonymous ftp),
\\[mh-mhn-compose-external-compressed-tar] \
\(reference to compressed tar file via anonymous ftp), and
\\[mh-mhn-compose-forw] (forward message)."
  (interactive "*")
  (save-buffer)
  (message "mhn editing...")
  (mh-exec-cmd-error (format "mhdraft=%s" (buffer-file-name))
		     "mhn" (buffer-file-name))
  (revert-buffer t t)
  (message "mhn editing...done"))


(defun mh-revert-mhn-edit (noconfirm)
  "Undoes the effect of \\[mh-edit-mhn] by reverting to the backup file.
Argument (optional) non-nil means don't ask for confirmation."
  (interactive "*P")
  (if (null buffer-file-name)
      (error "Buffer does not seem to be associated with any file"))
  (let ((backup-strings '("," "#"))
	backup-file)
    (while (and backup-strings
		(not (file-exists-p
		      (setq backup-file
			    (concat (file-name-directory buffer-file-name)
				    (car backup-strings)
				    (file-name-nondirectory buffer-file-name)
				    ".orig")))))
      (setq backup-strings (cdr backup-strings)))
    (or backup-strings
	(error "mhn backup file for %s no longer exists!" buffer-file-name))
    (or noconfirm
	(yes-or-no-p (format "Revert buffer from file %s? "
			     backup-file))
	(error "mhn edit revert not confirmed."))
    (let ((buffer-read-only nil))
      (erase-buffer)
      (insert-file-contents backup-file))
    (after-find-file nil)))