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[emacs.git] / lisp / mh-e / mh-mime.el

;;; mh-mime.el --- MH-E support for composing MIME messages

;; Copyright (C) 1993, 1995, 2001, 2002 Free Software Foundation, Inc.

;; Author: Bill Wohler <wohler@newt.com>
;; Maintainer: Bill Wohler <wohler@newt.com>
;; Keywords: mail
;; See: mh-e.el

;; This file is part of GNU Emacs.

;; GNU Emacs 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.

;; GNU Emacs 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., 59 Temple Place - Suite 330,
;; Boston, MA 02111-1307, 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.

;;; Change Log:

;; $Id: mh-mime.el,v 1.100 2003/01/25 19:18:51 satyaki Exp $

;;; Code:

(require 'cl)
(require 'mh-comp)
(require 'mh-utils)
(load "mm-decode" t t)                  ; Non-fatal dependency
(load "mm-uu" t t)                      ; Non-fatal dependency
(load "mailcap" t t)                    ; Non-fatal dependency
(load "smiley" t t)                     ; Non-fatal dependency
(require 'gnus-util)

(autoload 'gnus-article-goto-header "gnus-art")
(autoload 'article-emphasize "gnus-art")
(autoload 'gnus-get-buffer-create "gnus")
(autoload 'gnus-eval-format "gnus-spec")
(autoload 'widget-convert-button "wid-edit")
(autoload 'message-options-set-recipient "message")
(autoload 'mml-secure-message-sign-pgpmime "mml-sec")
(autoload 'mml-secure-message-encrypt-pgpmime "mml-sec")
(autoload 'mml-minibuffer-read-file "mml")
(autoload 'mml-minibuffer-read-description "mml")
(autoload 'mml-insert-empty-tag "mml")
(autoload 'mml-to-mime "mml")
(autoload 'mml-attach-file "mml")

;;;###mh-autoload
(defun mh-compose-insertion (&optional inline)
  "Add a directive to insert a MIME part from a file, using mhn or gnus.
If the variable `mh-compose-insertion' is set to 'mhn, then that will be used.
If it is set to 'gnus, then that will be used instead.
Optional argument INLINE means make it an inline attachment."
  (interactive "P")
  (if (equal mh-compose-insertion 'gnus)
      (if inline
          (mh-mml-attach-file "inline")
        (mh-mml-attach-file))
    (call-interactively 'mh-mhn-compose-insertion)))

;;;###mh-autoload
(defun mh-compose-forward (&optional description folder message)
  "Add a MIME directive to forward a message, using mhn or gnus.
If the variable `mh-compose-insertion' is set to 'mhn, then that will be used.
If it is set to 'gnus, then that will be used instead.
Optional argument DESCRIPTION is a description of the attachment.
Optional argument FOLDER is the folder from which the forwarded message should
come.
Optional argument MESSAGE is the message to forward.
If any of the optional arguments are absent, they are prompted for."
  (interactive (list
                (read-string "Forw Content-description: ")
                (mh-prompt-for-folder "Message from" mh-sent-from-folder nil)
                (read-string (format "Messages%s: "
                                     (if mh-sent-from-msg
                                         (format " [%d]" mh-sent-from-msg)
                                       "")))))
  (if (equal mh-compose-insertion 'gnus)
      (mh-mml-forward-message description folder message)
    (mh-mhn-compose-forw description folder message)))

;; 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-mhn-args nil
  "Extra arguments to have \\[mh-edit-mhn] pass to the \"mhn\" command.
The arguments are passed to mhn if \\[mh-edit-mhn] is given a
prefix argument.  Normally default arguments to mhn are specified in the
MH profile.")

(defvar mh-media-type-regexp
  (concat (regexp-opt '("text" "image" "audio" "video" "application"
                        "multipart" "message") t)
          "/[-.+a-zA-Z0-9]+")
  "Regexp matching valid media types used in MIME attachment compositions.")

;; Just defvar the variable to avoid compiler warning... This doesn't bind
;; the variable, so things should work exactly as before.
(defvar mh-have-file-command)

(defun mh-have-file-command ()
  "Return t if 'file' command is on the system.
'file -i' is used to get MIME type of composition insertion."
  (when (not (boundp 'mh-have-file-command))
    (load "executable" t t)        ; executable-find not autoloaded in emacs20
    (setq mh-have-file-command
          (and (fboundp 'executable-find)
               (executable-find "file") ; file command exists
                                        ;   and accepts -i and -b args.
               (zerop (call-process "file" nil nil nil "-i" "-b"
                                    (expand-file-name "inc" mh-progs))))))
  mh-have-file-command)

(defvar mh-file-mime-type-substitutions
  '(("application/msword" "\.xls" "application/ms-excel")
    ("application/msword" "\.ppt" "application/ms-powerpoint"))
  "Substitutions to make for Content-Type returned from file command.
The first element is the Content-Type returned by the file command.
The second element is a regexp matching the file name, usually the extension.
The third element is the Content-Type to replace with.")

(defun mh-file-mime-type-substitute (content-type filename)
  "Return possibly changed CONTENT-TYPE on the FILENAME.
Substitutions are made from the `mh-file-mime-type-substitutions' variable."
  (let ((subst mh-file-mime-type-substitutions)
        (type) (match) (answer content-type)
        (case-fold-search t))
    (while subst
      (setq type (car (car subst))
            match (elt (car subst) 1))
      (if (and (string-equal content-type type)
               (string-match match filename))
          (setq answer (elt (car subst) 2)
                subst nil)
        (setq subst (cdr subst))))
    answer))

(defun mh-file-mime-type (filename)
  "Return MIME type of FILENAME from file command.
Returns nil if file command not on system."
  (cond
   ((not (mh-have-file-command))
    nil)                                ;No file command, exit now.
   ((not (and (file-exists-p filename)(file-readable-p filename)))
    nil)
   (t
    (save-excursion
      (let ((tmp-buffer (get-buffer-create mh-temp-buffer)))
        (set-buffer tmp-buffer)
        (unwind-protect
            (progn
              (call-process "file" nil '(t nil) nil "-b" "-i"
                            (expand-file-name filename))
              (goto-char (point-min))
              (if (not (re-search-forward mh-media-type-regexp nil t))
                  nil
                (mh-file-mime-type-substitute (match-string 0) filename)))
          (kill-buffer tmp-buffer)))))))

;;; This is needed for Emacs20 which doesn't have mailcap-mime-types.
(defvar mh-mime-content-types
  '(("application/mac-binhex40") ("application/msword")
    ("application/octet-stream") ("application/pdf") ("application/pgp-keys")
    ("application/pgp-signature") ("application/pkcs7-signature")
    ("application/postscript") ("application/rtf")
    ("application/vnd.ms-excel") ("application/vnd.ms-powerpoint")
    ("application/vnd.ms-project") ("application/vnd.ms-tnef")
    ("application/wordperfect5.1") ("application/wordperfect6.0")
    ("application/zip")

    ("audio/basic") ("audio/mpeg")

    ("image/gif") ("image/jpeg") ("image/png")

    ("message/delivery-status")
    ("message/external-body") ("message/partial") ("message/rfc822")

    ("text/enriched") ("text/html") ("text/plain") ("text/rfc822-headers")
    ("text/richtext") ("text/xml")

    ("video/mpeg") ("video/quicktime"))
  "Legal MIME content types.
See documentation for \\[mh-edit-mhn].")

;;;###mh-autoload
(defun mh-mhn-compose-insertion (filename type description attributes)
  "Add a directive to insert a MIME message part from a file.
This is the typical way to insert non-text parts in a message.

Arguments are FILENAME, which tells where to find the file, TYPE, the MIME
content type, DESCRIPTION, a line of text for the Content-Description field.
ATTRIBUTES is a comma separated list of name=value pairs that is appended to
the Content-Type field of the attachment.

See also \\[mh-edit-mhn]."
  (interactive (let ((filename (read-file-name "Insert contents of: ")))
                 (list
                  filename
                  (or (mh-file-mime-type filename)
                      (completing-read "Content-Type: "
                                       (if (fboundp 'mailcap-mime-types)
                                           (mapcar 'list (mailcap-mime-types))
                                         mh-mime-content-types)))
                  (read-string "Content-Description: ")
                  (read-string "Content-Attributes: "
                               (concat "name=\""
                                       (file-name-nondirectory filename)
                                       "\"")))))
  (mh-mhn-compose-type filename type description attributes ))

(defun mh-mhn-compose-type (filename type
                                     &optional description attributes comment)
  "Insert a mhn directive to insert a file.

The file specified by FILENAME is encoded as TYPE. An optional DESCRIPTION is
used as the Content-Description field, optional set of ATTRIBUTES and an
optional COMMENT can also be included."
  (setq mh-mhn-compose-insert-flag t)
  (beginning-of-line)
  (insert "#" type)
  (and attributes
       (insert "; " attributes))
  (and comment
       (insert " (" comment ")"))
  (insert " [")
  (and description
       (insert description))
  (insert "] " (expand-file-name filename))
  (insert "\n"))


;;;###mh-autoload
(defun mh-mhn-compose-anon-ftp (host filename type description)
  "Add a directive for a MIME anonymous ftp external body part.
This directive tells MH to include a reference to a message/external-body part
retrievable by anonymous FTP.

Arguments are HOST and FILENAME, which tell where to find the file, TYPE, the
MIME content type, and DESCRIPTION, a line of text for the Content-description
header.

See also \\[mh-edit-mhn]."
  (interactive (list
                (read-string "Remote host: ")
                (read-string "Remote filename: ")
                (completing-read "External Content-Type: "
                                 (if (fboundp 'mailcap-mime-types)
                                     (mapcar 'list (mailcap-mime-types))
                                   mh-mime-content-types))
                (read-string "External Content-Description: ")))
  (mh-mhn-compose-external-type "anon-ftp" host filename
                                type description))

;;;###mh-autoload
(defun mh-mhn-compose-external-compressed-tar (host filename description)
  "Add a directive to include a MIME 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.

Arguments are HOST and FILENAME, which tell where to find the file, and
DESCRIPTION, a line of text for the Content-description header.

See also \\[mh-edit-mhn]."
  (interactive (list
                (read-string "Remote host: ")
                (read-string "Remote filename: ")
                (read-string "Tar file Content-description: ")))
  (mh-mhn-compose-external-type "anon-ftp" host filename
                                "application/octet-stream"
                                description
                                "type=tar; conversions=x-compress"
                                "mode=image"))


(defun mh-mhn-compose-external-type (access-type host filename type
                                                 &optional description
                                                 attributes extra-params
                                                 comment)
  "Add a directive to include a MIME reference to a remote file.
The file should be available via anonymous ftp. This directive tells MH to
include a reference to a message/external-body part.

Arguments are ACCESS-TYPE, HOST and FILENAME, which tell where to find the
file and TYPE which is the MIME Content-Type. Optional arguments include
DESCRIPTION, a line of text for the Content-description header, ATTRIBUTES,
EXTRA-PARAMS, and COMMENT.

See also \\[mh-edit-mhn]."
  (setq mh-mhn-compose-insert-flag t)
  (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 filename))
  (insert "; directory=\"" (file-name-directory filename) "\"")
  (and extra-params
       (insert "; " extra-params))
  (insert "\n"))

;;;###mh-autoload
(defun mh-mhn-compose-forw (&optional description folder messages)
  "Add a forw directive to this message, to forward a message with MIME.
This directive tells MH to include the named messages in this one.

Arguments are DESCRIPTION, a line of text for the Content-description header,
and FOLDER and MESSAGES, which name the message(s) to be forwarded.

See also \\[mh-edit-mhn]."
  (interactive (list
                (read-string "Forw Content-description: ")
                (mh-prompt-for-folder "Message from" mh-sent-from-folder nil)
                (read-string (format "Messages%s: "
                                     (if mh-sent-from-msg
                                         (format " [%d]" mh-sent-from-msg)
                                       "")))))
  (setq mh-mhn-compose-insert-flag t)
  (beginning-of-line)
  (insert "#forw [")
  (and description
       (not (string= description ""))
       (insert description))
  (insert "]")
  (and folder
       (not (string= folder ""))
       (insert " " folder))
  (if (and messages
           (not (string= messages "")))
      (let ((start (point)))
        (insert " " messages)
        (subst-char-in-region start (point) ?, ? ))
    (if mh-sent-from-msg
        (insert " " (int-to-string mh-sent-from-msg))))
  (insert "\n"))

;;;###mh-autoload
(defun mh-edit-mhn (&optional extra-args)
  "Format the current draft for MIME, expanding any mhn directives.

Process the current draft with the mhn program, which, 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 `\\[mh-revert-mhn-edit]' command undoes this command. The arguments in the
list `mh-mhn-args' are passed to mhn if this function is passed an optional
prefix argument EXTRA-ARGS.

For assistance with creating mhn 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). If these helper functions are used, `mh-edit-mhn' is run
automatically when the draft is sent.

The value of `mh-edit-mhn-hook' is a list of functions to be called, with no
arguments, after performing the conversion.

The mhn program is part of MH version 6.8 or later."
  (interactive "*P")
  (save-buffer)
  (message "mhn editing...")
  (cond
   (mh-nmh-flag
    (mh-exec-cmd-error nil
                       "mhbuild" (if extra-args mh-mhn-args) buffer-file-name))
   (t
    (mh-exec-cmd-error (format "mhdraft=%s" buffer-file-name)
                       "mhn" (if extra-args mh-mhn-args) buffer-file-name)))
  (setq mh-mhn-compose-insert-flag nil)
  (revert-buffer t t)
  (message "mhn editing...done")
  (run-hooks 'mh-edit-mhn-hook))

;;;###mh-autoload
(defun mh-revert-mhn-edit (noconfirm)
  "Undo the effect of \\[mh-edit-mhn] by reverting to the backup file.
Optional non-nil argument NOCONFIRM 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 "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 "Revert not confirmed"))
    (let ((buffer-read-only nil))
      (erase-buffer)
      (insert-file-contents backup-file))
    (after-find-file nil)))

\f

;;; MIME composition functions

;;;###mh-autoload
(defun mh-mml-to-mime ()
  "Compose MIME message from mml directives."
  (interactive)
  (when mh-gnus-pgp-support-flag ;; This is only needed for PGP
    (message-options-set-recipient))
  (mml-to-mime)
  (setq mh-mml-compose-insert-flag nil))

;;;###mh-autoload
(defun mh-mml-forward-message (description folder message)
  "Forward a message as attachment.
The function will prompt the user for a DESCRIPTION, a FOLDER and MESSAGE
number."
  (let ((msg (if (equal message "")
                 mh-sent-from-msg
               (car (read-from-string message)))))
    (cond ((integerp msg)
           (if (string= "" description)
               ;; Rationale: mml-attach-file constructs a malformed composition
               ;; if the description string is empty.  This fixes SF #625168.
               (mml-attach-file (format "%s%s/%d"
                                        mh-user-path (substring folder 1) msg)
                                "message/rfc822")
             (mml-attach-file (format "%s%s/%d"
                                      mh-user-path (substring folder 1) msg)
                              "message/rfc822"
                              description))
           (setq mh-mml-compose-insert-flag t))
          (t (error "The message number, %s is not a integer!" msg)))))

;;;###mh-autoload
(defun mh-mml-attach-file (&optional disposition)
  "Attach a file to the outgoing MIME message.
The file is not inserted or encoded until you send the message with
`\\[mh-send-letter]'.
Message disposition is \"inline\" or \"attachment\" and is prompted for if
DISPOSITION is nil.

This is basically `mml-attach-file' from gnus, modified such that a prefix
argument yields an `inline' disposition and Content-Type is determined
automatically."
  (let* ((file (mml-minibuffer-read-file "Attach file: "))
         (type (or (mh-file-mime-type file)
                   (completing-read "Content-Type: "
                                    (if (fboundp 'mailcap-mime-types)
                                        (mapcar 'list (mailcap-mime-types))
                                      mh-mime-content-types))))
         (description (mml-minibuffer-read-description))
         (dispos (or disposition
                     (completing-read "Disposition: [attachment] "
                                      '(("attachment")("inline"))
                                      nil t nil nil
                                      "attachment"))))
    (mml-insert-empty-tag 'part 'type type 'filename file
                          'disposition dispos 'description description)
    (setq mh-mml-compose-insert-flag t)))

;;;###mh-autoload
(defun mh-mml-secure-message-sign-pgpmime ()
  "Add directive to encrypt/sign the entire message."
  (interactive)
  (if (not mh-gnus-pgp-support-flag)
      (error "Sorry.  Your version of gnus does not support PGP/GPG")
    (mml-secure-message-sign-pgpmime)
    (setq mh-mml-compose-insert-flag t)))

;;;###mh-autoload
(defun mh-mml-secure-message-encrypt-pgpmime (&optional dontsign)
  "Add directive to encrypt and sign the entire message.
If called with a prefix argument DONTSIGN, only encrypt (do NOT sign)."
  (interactive "P")
  (if (not mh-gnus-pgp-support-flag)
      (error "Sorry.  Your version of gnus does not support PGP/GPG")
    (mml-secure-message-encrypt-pgpmime dontsign)
    (setq mh-mml-compose-insert-flag t)))

\f

;;; MIME decoding

(defmacro mh-defun-compat (function arg-list &rest body)
  "This is a macro to define functions which are not defined.
It is used for Gnus utility functions which were added recently. If FUNCTION
is not defined then it is defined to have argument list, ARG-LIST and body,
BODY."
  (let ((defined-p (fboundp function)))
    (unless defined-p
      `(defun ,function ,arg-list ,@body))))
(put 'mh-defun-compat 'lisp-indent-function 'defun)

;; Copy of original function from gnus-util.el
(mh-defun-compat gnus-local-map-property (map)
  "Return a list suitable for a text property list specifying keymap MAP."
  (cond (mh-xemacs-flag (list 'keymap map))
        ((>= emacs-major-version 21) (list 'keymap map))
        (t (list 'local-map map))))

;; Copy of original function from mm-decode.el
(mh-defun-compat mm-merge-handles (handles1 handles2)
  (append (if (listp (car handles1)) handles1 (list handles1))
          (if (listp (car handles2)) handles2 (list handles2))))

;; Copy of function from mm-decode.el
(mh-defun-compat mm-set-handle-multipart-parameter (handle parameter value)
  ;; HANDLE could be a CTL.
  (if handle
      (put-text-property 0 (length (car handle)) parameter value
                         (car handle))))

;; Copy of original macro is in mm-decode.el
(mh-defun-compat mm-handle-multipart-ctl-parameter (handle parameter)
  (get-text-property 0 parameter (car handle)))

;; Copy of original function in mm-decode.el
(mh-defun-compat mm-readable-p (handle)
  "Say whether the content of HANDLE is readable."
  (and (< (with-current-buffer (mm-handle-buffer handle)
            (buffer-size)) 10000)
       (mm-with-unibyte-buffer
         (mm-insert-part handle)
         (and (eq (mm-body-7-or-8) '7bit)
              (not (mm-long-lines-p 76))))))

;; Copy of original function in mm-bodies.el
(mh-defun-compat mm-long-lines-p (length)
  "Say whether any of the lines in the buffer is longer than LINES."
  (save-excursion
    (goto-char (point-min))
    (end-of-line)
    (while (and (not (eobp))
                (not (> (current-column) length)))
      (forward-line 1)
      (end-of-line))
    (and (> (current-column) length)
         (current-column))))

(mh-defun-compat mm-keep-viewer-alive-p (handle)
  ;; Released Gnus doesn't keep handles associated with externally displayed
  ;; MIME parts. So this will always return nil.
  nil)

(mh-defun-compat mm-destroy-parts (list)
  "Older emacs don't have this function."
  nil)

;;; This is mm-save-part from gnus 5.10 since that function in emacs21.2 is
;;; buggy (the args to read-file-name are incorrect). When all supported
;;; versions of Emacs come with at least Gnus 5.10, we can delete this
;;; function and rename calls to mh-mm-save-part to mm-save-part.
(defun mh-mm-save-part (handle)
  "Write HANDLE to a file."
  (let ((name (mail-content-type-get (mm-handle-type handle) 'name))
        (filename (mail-content-type-get
                   (mm-handle-disposition handle) 'filename))
        file)
    (when filename
      (setq filename (file-name-nondirectory filename)))
    (setq file (read-file-name "Save MIME part to: "
                               (or mm-default-directory
                                   default-directory)
                               nil nil (or filename name "")))
    (setq mm-default-directory (file-name-directory file))
    (and (or (not (file-exists-p file))
             (yes-or-no-p (format "File %s already exists; overwrite? "
                                  file)))
         (mm-save-part-to-file handle file))))

\f

;;; MIME cleanup

;;;###mh-autoload
(defun mh-mime-cleanup ()
  "Free the decoded MIME parts."
  (let ((mime-data (gethash (current-buffer) mh-globals-hash)))
    ;; This is for Emacs, what about XEmacs?
    (cond ((fboundp 'remove-images)
           (remove-images (point-min) (point-max))))
    (when mime-data
      (mm-destroy-parts (mh-mime-handles mime-data))
      (remhash (current-buffer) mh-globals-hash))))

;;;###mh-autoload
(defun mh-destroy-postponed-handles ()
  "Free MIME data for externally displayed mime parts."
  (let ((mime-data (mh-buffer-data)))
    (when mime-data
      (mm-destroy-parts (mh-mime-handles mime-data)))
    (remhash (current-buffer) mh-globals-hash)))

(defun mh-handle-set-external-undisplayer (folder handle function)
  "Replacement for `mm-handle-set-external-undisplayer'.
This is only called in recent versions of Gnus. The MIME handles are stored
in data structures corresponding to MH-E folder buffer FOLDER instead of in
Gnus (as in the original). The MIME part, HANDLE is associated with the
undisplayer FUNCTION."
  (if (mm-keep-viewer-alive-p handle)
      (let ((new-handle (copy-sequence handle)))
        (mm-handle-set-undisplayer new-handle function)
        (mm-handle-set-undisplayer handle nil)
        (save-excursion
          (set-buffer folder)
          (push new-handle (mh-mime-handles (mh-buffer-data)))))
    (mm-handle-set-undisplayer handle function)))

\f

;;; MIME transformations
(eval-when-compile (require 'font-lock))

;;;###mh-autoload
(defun mh-add-missing-mime-version-header ()
  "Some mail programs don't put a MIME-Version header.
I have seen this only in spam, so maybe we shouldn't fix this ;-)"
  (save-excursion
    (goto-char (point-min))
    (when (and (message-fetch-field "content-type")
               (not (message-fetch-field "mime-version")))
      (when (search-forward "\n\n" nil t)
        (forward-line -1)
        (insert "MIME-Version: 1.0\n")))))

;;;###mh-autoload
(defun mh-display-smileys ()
  "Function to display smileys."
  (when (and mh-graphical-smileys-flag
             (fboundp 'smiley-region)
             (boundp 'font-lock-maximum-size)
             (>= (/ font-lock-maximum-size 8) (buffer-size)))
    (smiley-region (point-min) (point-max))))

;;;###mh-autoload
(defun mh-display-emphasis ()
  "Function to display graphical emphasis."
  (when (and mh-graphical-emphasis-flag
             (boundp 'font-lock-maximum-size)
             (>= (/ font-lock-maximum-size 8) (buffer-size)))
    (flet ((article-goto-body ()))      ; shadow this function to do nothing
      (save-excursion
        (goto-char (point-min))
        (article-emphasize)))))

;; Copied from gnus-art.el (should be checked for other cool things that can
;; be added to the buttons)
(defvar mh-mime-button-commands
  '((mh-press-button "\r" "Toggle Display")))
(defvar mh-mime-button-map
  (let ((map (make-sparse-keymap)))
    (unless (>= (string-to-number emacs-version) 21)
      ;; XEmacs doesn't care.
      (set-keymap-parent map mh-show-mode-map))
    (define-key map [mouse-2] 'mh-push-button)
    (dolist (c mh-mime-button-commands)
      (define-key map (cadr c) (car c)))
    map))
(defvar mh-mime-button-line-format-alist
  '((?T long-type ?s)
    (?d description ?s)
    (?p index ?s)
    (?e dots ?s)))
(defvar mh-mime-button-line-format "%{%([%p. %d%T]%)%}%e\n")
(defvar mh-mime-security-button-pressed nil)
(defvar mh-mime-security-button-line-format "%{%([[%t:%i]%D]%)%}\n")
(defvar mh-mime-security-button-end-line-format "%{%([[End of %t]%D]%)%}\n")
(defvar mh-mime-security-button-line-format-alist
  '((?t type ?s)
    (?i info ?s)
    (?d details ?s)
    (?D pressed-details ?s)))
(defvar mh-mime-security-button-map
  (let ((map (make-sparse-keymap)))
    (unless (>= (string-to-number emacs-version) 21)
      (set-keymap-parent map mh-show-mode-map))
    (define-key map "\r" 'mh-press-button)
    (define-key map [mouse-2] 'mh-push-button)
    map))

(defvar mh-mime-save-parts-directory nil
  "Default to use for `mh-mime-save-parts-default-directory'.
Set from last use.")

;;;###mh-autoload
(defun mh-mime-save-parts (arg)
  "Store the MIME parts of the current message.
If ARG, prompt for directory, else use that specified by the variable
`mh-mime-save-parts-default-directory'. These directories may be superseded by
mh_profile directives, since this function calls on mhstore or mhn to do the
actual storing."
  (interactive "P")
  (let ((msg (if (eq major-mode 'mh-show-mode)
                 (mh-show-buffer-message-number)
               (mh-get-msg-num t)))
        (folder (if (eq major-mode 'mh-show-mode)
                    mh-show-folder-buffer
                  mh-current-folder))
        (command (if mh-nmh-flag "mhstore" "mhn"))
        (directory
         (cond
          ((and (or arg
                    (equal nil mh-mime-save-parts-default-directory)
                    (equal t mh-mime-save-parts-default-directory))
                (not mh-mime-save-parts-directory))
           (read-file-name "Store in what directory? " nil nil t nil))
          ((and (or arg
                    (equal t mh-mime-save-parts-default-directory))
                mh-mime-save-parts-directory)
           (read-file-name (format
                            "Store in what directory? [%s] "
                            mh-mime-save-parts-directory)
                           "" mh-mime-save-parts-directory t ""))
          ((stringp mh-mime-save-parts-default-directory)
           mh-mime-save-parts-default-directory)
          (t
           mh-mime-save-parts-directory))))
    (if (and (equal directory "") mh-mime-save-parts-directory)
        (setq directory mh-mime-save-parts-directory))
    (if (not (file-directory-p directory))
        (message "No directory specified.")
      (if (equal nil mh-mime-save-parts-default-directory)
          (setq mh-mime-save-parts-directory directory))
      (save-excursion
        (set-buffer (get-buffer-create " *mh-store*"))
        (cd directory)
        (setq mh-mime-save-parts-directory directory)
        (erase-buffer)
        (apply 'call-process
               (expand-file-name command mh-progs) nil t nil
               (mh-list-to-string (list folder msg "-auto")))
        (if (> (buffer-size) 0)
            (save-window-excursion
              (switch-to-buffer-other-window " *mh-store*")
              (sit-for 3)))))))

;; Avoid errors if gnus-sum isn't loaded yet...
(defvar gnus-newsgroup-charset nil)
(defvar gnus-newsgroup-name nil)

;;;###mh-autoload
(defun mh-mime-display (&optional pre-dissected-handles)
  "Display (and possibly decode) MIME handles.
Optional argument, PRE-DISSECTED-HANDLES is a list of MIME handles. If
present they are displayed otherwise the buffer is parsed and then
displayed."
  (let ((handles ())
        (folder mh-show-folder-buffer))
    (flet ((mm-handle-set-external-undisplayer
            (handle function)
            (mh-handle-set-external-undisplayer folder handle function)))
      ;; If needed dissect the current buffer
      (if pre-dissected-handles
          (setq handles pre-dissected-handles)
        (setq handles (or (mm-dissect-buffer nil) (mm-uu-dissect)))
        (setf (mh-mime-handles (mh-buffer-data))
              (mm-merge-handles handles (mh-mime-handles (mh-buffer-data))))

        ;; Use charset to decode body...
        (unless handles
          (let* ((ct (ignore-errors
                       (mail-header-parse-content-type
                        (message-fetch-field "Content-Type" t))))
                 (charset (mail-content-type-get ct 'charset)))
            (when (stringp charset)
              (mm-decode-body charset)))))

      (when (and handles (or (not (stringp (car handles))) (cdr handles)))
        ;; Goto start of message body
        (goto-char (point-min))
        (or (search-forward "\n\n" nil t) (goto-char (point-max)))

        ;; Delete the body
        (delete-region (point) (point-max))

        ;; Display the MIME handles
        (mh-mime-display-part handles)))))

(defun mh-mime-display-part (handle)
  "Decides the viewer to call based on the type of HANDLE."
  (cond ((null handle) nil)
        ((not (stringp (car handle)))
         (mh-mime-display-single handle))
        ((equal (car handle) "multipart/alternative")
         (mh-mime-display-alternative (cdr handle)))
        ((and mh-gnus-pgp-support-flag
              (or (equal (car handle) "multipart/signed")
                  (equal (car handle) "multipart/encrypted")))
         (mh-mime-display-security handle))
        (t (mh-mime-display-mixed (cdr handle)))))

(defun mh-mime-display-alternative (handles)
  "Choose among the alternatives, HANDLES the part that will be displayed.
If no part is preferred then all the parts are displayed."
  (let ((preferred (mm-preferred-alternative handles)))
    (cond ((and preferred (stringp (car preferred)))
           (mh-mime-display-part preferred))
          (preferred
           (save-restriction
             (narrow-to-region (point) (if (eobp) (point) (1+ (point))))
             (mh-mime-display-single preferred)
             (goto-char (point-max))))
          (t (mh-mime-display-mixed handles)))))

(defun mh-mime-display-mixed (handles)
  "Display the list of MIME parts, HANDLES recursively."
  (mapcar #'mh-mime-display-part handles))

(defun mh-mime-part-index (handle)
  "Generate the button number for MIME part, HANDLE.
Notice that a hash table is used to display the same number when buttons need
to be displayed multiple times (for instance when nested messages are
opened)."
  (or (gethash handle (mh-mime-part-index-hash (mh-buffer-data)))
      (setf (gethash handle (mh-mime-part-index-hash (mh-buffer-data)))
            (incf (mh-mime-parts-count (mh-buffer-data))))))

;;; Avoid compiler warnings for XEmacs functions...
(eval-when (compile)
  (loop for function in '(glyph-width window-pixel-width
                                      glyph-height window-pixel-height)
        do (or (fboundp function) (defalias function 'ignore))))

(defun mh-small-image-p (handle)
  "Decide whether HANDLE is a \"small\" image that can be displayed inline.
This is only useful if a Content-Disposition header is not present."
  (let ((media-test (caddr (assoc (car (mm-handle-type handle))
                                  mh-mm-inline-media-tests)))
        (mm-inline-large-images t))
    (and media-test
         (equal (mm-handle-media-supertype handle) "image")
         (funcall media-test handle)    ; Since mm-inline-large-images is T,
                                        ; this only tells us if the image is
                                        ; something that emacs can display
         (let* ((image (mm-get-image handle)))
           (cond ((fboundp 'glyph-width)
                  ;; XEmacs -- totally untested, copied from gnus
                  (and (< (glyph-width image)
                          (or mh-max-inline-image-width
                              (window-pixel-width)))
                       (< (glyph-height image)
                          (or mh-max-inline-image-height
                              (window-pixel-height)))))
                 ((fboundp 'image-size)
                  ;; Emacs21 -- copied from gnus
                  (let ((size (image-size image)))
                    (and (< (cdr size)
                            (or mh-max-inline-image-height
                                (1- (window-height))))
                         (< (car size)
                            (or mh-max-inline-image-width (window-width))))))
                 (t
                  ;; Can't show image inline
                  nil))))))

(defun mh-inline-vcard-p (handle)
  "Decide if HANDLE is a vcard that must be displayed inline."
  (let ((type (mm-handle-type handle)))
    (and (consp type)
         (equal (car type) "text/x-vcard")
         (save-excursion
           (save-restriction
             (widen)
             (goto-char (point-min))
             (not (re-search-forward "^-- $" nil t)))))))

(defun mh-mime-display-single (handle)
  "Display a leaf node, HANDLE in the MIME tree."
  (let* ((type (mm-handle-media-type handle))
         (small-image-flag (mh-small-image-p handle))
         (attachmentp (equal (car (mm-handle-disposition handle))
                             "attachment"))
         (inlinep (and (equal (car (mm-handle-disposition handle)) "inline")
                       (mm-inlinable-p handle)
                       (mm-inlined-p handle)))
         (displayp (or inlinep                   ; show if inline OR
                       (mh-inline-vcard-p handle);      inline vcard OR
                       (and (not attachmentp)    ;      if not an attachment
                            (or small-image-flag ;        and small image
                                                 ;        and user wants inline
                                (and (not (equal
                                           (mm-handle-media-supertype handle)
                                           "image"))
                                     (mm-inlinable-p handle)
                                     (mm-inlined-p handle)))))))
    (save-restriction
      (narrow-to-region (point) (if (eobp) (point) (1+ (point))))
      (cond ((and mh-gnus-pgp-support-flag
                  (equal type "application/pgp-signature"))
             nil)             ; skip signatures as they are already handled...
            ((not displayp)
             (insert "\n")
             (mh-insert-mime-button handle (mh-mime-part-index handle) nil))
            ((and displayp (not mh-display-buttons-for-inline-parts-flag))
             (or (mm-display-part handle) (mm-display-part handle)))
            ((and displayp mh-display-buttons-for-inline-parts-flag)
             (insert "\n")
             (mh-insert-mime-button handle (mh-mime-part-index handle) nil)
             (forward-line -1)
             (mh-mm-display-part handle)))
      (goto-char (point-max)))))

(defun mh-insert-mime-button (handle index displayed)
  "Insert MIME button for HANDLE.
INDEX is the part number that will be DISPLAYED. It is also used by commands
like \"K v\" which operate on individual MIME parts."
  ;; The button could be displayed by a previous decode. In that case
  ;; undisplay it if we need a hidden button.
  (when (and (mm-handle-displayed-p handle) (not displayed))
    (mm-display-part handle))
  (let ((name (or (mail-content-type-get (mm-handle-type handle) 'name)
                  (mail-content-type-get (mm-handle-disposition handle)
                                         'filename)
                  (mail-content-type-get (mm-handle-type handle) 'url)
                  ""))
        (type (mm-handle-media-type handle))
        (description (mail-decode-encoded-word-string
                      (or (mm-handle-description handle) "")))
        (dots (if (or displayed (mm-handle-displayed-p handle)) "   " "..."))
        long-type begin end)
    (if (string-match ".*/" name) (setq name (substring name (match-end 0))))
    (setq long-type (concat type (and (not (equal name ""))
                                      (concat "; " name))))
    (unless (equal description "")
      (setq long-type (concat " --- " long-type)))
    (unless (bolp) (insert "\n"))
    (setq begin (point))
    (gnus-eval-format
     mh-mime-button-line-format mh-mime-button-line-format-alist
     `(,@(gnus-local-map-property mh-mime-button-map)
         mh-callback mh-mm-display-part
         mh-part ,index
         mh-data ,handle))
    (setq end (point))
    (widget-convert-button
     'link begin end
     :mime-handle handle
     :action 'mh-widget-press-button
     :button-keymap mh-mime-button-map
     :help-echo
     "Mouse-2 click or press RET (in show buffer) to toggle display")))

;; There is a bug in Gnus inline image display due to which an extra line
;; gets inserted every time it is viewed. To work around that problem we are
;; using an extra property 'mh-region to remember the region that is added
;; when the button is clicked. The region is then deleted to make sure that
;; no extra lines get inserted.
(defun mh-mm-display-part (handle)
  "Toggle display of button for MIME part, HANDLE."
  (beginning-of-line)
  (let ((id (get-text-property (point) 'mh-part))
        (point (point))
        (window (selected-window))
        (mail-parse-charset 'nil)
        (mail-parse-ignored-charsets nil)
        region buffer-read-only)
    (save-excursion
      (unwind-protect
          (let ((win (get-buffer-window (current-buffer) t)))
            (when win
              (select-window win))
            (goto-char point)

            (if (mm-handle-displayed-p handle)
                ;; This will remove the part.
                (progn
                  ;; Delete the button and displayed part (if any)
                  (let ((region (get-text-property point 'mh-region)))
                    (when region
                      (when (fboundp 'remove-images)
                        (remove-images (car region) (cdr region))))
                    (mm-display-part handle)
                    (when region
                      (delete-region (car region) (cdr region))))
                  ;; Delete button (if it still remains). This happens for
                  ;; externally displayed parts where the previous step does
                  ;; nothing.
                  (unless (eolp)
                    (delete-region (point) (progn (forward-line) (point)))))
              (save-restriction
                (delete-region (point) (progn (forward-line 1) (point)))
                (narrow-to-region (point) (point))
                ;; Maybe we need another unwind-protect here.
                (when (equal (mm-handle-media-supertype handle) "image")
                  (insert "\n"))
                (when (and (not (eq (ignore-errors (mm-display-part handle))
                                    'inline))
                           (equal (mm-handle-media-supertype handle)
                                  "image"))
                  (goto-char (point-min))
                  (delete-char 1))
                (when (equal (mm-handle-media-supertype handle) "text")
                  (when (eq mh-highlight-citation-p 'gnus)
                    (mh-gnus-article-highlight-citation))
                  (mh-display-smileys)
                  (mh-display-emphasis))
                (setq region (cons (progn (goto-char (point-min))
                                          (point-marker))
                                   (progn (goto-char (point-max))
                                          (point-marker)))))))
        (when (window-live-p window)
          (select-window window))
        (goto-char point)
        (beginning-of-line)
        (mh-insert-mime-button handle id (mm-handle-displayed-p handle))
        (goto-char point)
        (when region
          (add-text-properties (line-beginning-position) (line-end-position)
                               `(mh-region ,region)))))))

;;;###mh-autoload
(defun mh-press-button ()
  "Press MIME button.
If the MIME part is visible then it is removed. Otherwise the part is
displayed."
  (interactive)
  (let ((mm-inline-media-tests mh-mm-inline-media-tests)
        (data (get-text-property (point) 'mh-data))
        (function (get-text-property (point) 'mh-callback))
        (buffer-read-only nil)
        (folder mh-show-folder-buffer))
    (flet ((mm-handle-set-external-undisplayer
            (handle function)
            (mh-handle-set-external-undisplayer folder handle function)))
      (when (and function (eolp))
        (backward-char))
      (unwind-protect (and function (funcall function data))
        (set-buffer-modified-p nil)))))

;;;###mh-autoload
(defun mh-push-button (event)
  "Click MIME button for EVENT.
If the MIME part is visible then it is removed. Otherwise the part is
displayed. This function is called when the mouse is used to click the MIME
button."
  (interactive "e")
  (set-buffer (window-buffer (posn-window (event-start event))))
  (select-window (posn-window (event-start event)))
  (let* ((pos (posn-point (event-start event)))
         (folder mh-show-folder-buffer)
         (mm-inline-media-tests mh-mm-inline-media-tests)
         (data (get-text-property pos 'mh-data))
         (function (get-text-property pos 'mh-callback))
         (buffer-read-only nil))
    (flet ((mm-handle-set-external-undisplayer
            (handle function)
            (mh-handle-set-external-undisplayer folder handle function)))
      (goto-char pos)
      (unwind-protect (and function (funcall function data))
        (set-buffer-modified-p nil)))))

;;;###mh-autoload
(defun mh-mime-save-part ()
  "Save MIME part at point."
  (interactive)
  (let ((data (get-text-property (point) 'mh-data)))
    (when data
      (let ((mm-default-directory mh-mime-save-parts-directory))
        (mh-mm-save-part data)
        (setq mh-mime-save-parts-directory mm-default-directory)))))

;;;###mh-autoload
(defun mh-mime-inline-part ()
  "Toggle display of the raw MIME part."
  (interactive)
  (let* ((buffer-read-only nil)
         (data (get-text-property (point) 'mh-data))
         (inserted-flag (get-text-property (point) 'mh-mime-inserted))
         (displayed-flag (mm-handle-displayed-p data))
         (point (point))
         start end)
    (cond ((and data (not inserted-flag) (not displayed-flag))
           (let ((contents (mm-get-part data)))
             (add-text-properties (line-beginning-position) (line-end-position)
                                  '(mh-mime-inserted t))
             (setq start (point-marker))
             (forward-line 1)
             (mm-insert-inline data contents)
             (setq end (point-marker))
             (add-text-properties
              start (progn (goto-char start) (line-end-position))
              `(mh-region (,start . ,end)))))
          ((and data (or inserted-flag displayed-flag))
           (mh-press-button)
           (message "MIME part already inserted")))
    (goto-char point)
    (set-buffer-modified-p nil)))

(defun mh-widget-press-button (widget el)
  "Callback for widget, WIDGET.
Parameter EL is unused."
  (goto-char (widget-get widget :from))
  (mh-press-button))

(defun mh-mime-display-security (handle)
  "Display PGP encrypted/signed message, HANDLE."
  (insert "\n")
  (save-restriction
    (narrow-to-region (point) (point))
    (mh-insert-mime-security-button handle)
    (mh-mime-display-mixed (cdr handle))
    (insert "\n")
    (let ((mh-mime-security-button-line-format
           mh-mime-security-button-end-line-format))
      (mh-insert-mime-security-button handle))
    (mm-set-handle-multipart-parameter
     handle 'mh-region
     (cons (set-marker (make-marker) (point-min))
           (set-marker (make-marker) (point-max))))))

;;; I rewrote the security part because Gnus doesn't seem to ever minimize
;;; the button. That is once the mime-security button is pressed there seems
;;; to be no way of getting rid of the inserted text.
(defun mh-mime-security-show-details (handle)
  "Toggle display of detailed security info for HANDLE."
  (let ((details (mm-handle-multipart-ctl-parameter handle 'gnus-details)))
    (when details
      (let ((mh-mime-security-button-pressed
             (not (get-text-property (point) 'mh-button-pressed)))
            (mh-mime-security-button-line-format
             (get-text-property (point) 'mh-line-format)))
        (forward-char -1)
        (while (eq (get-text-property (point) 'mh-line-format)
                   mh-mime-security-button-line-format)
          (forward-char -1))
        (forward-char)
        (save-restriction
          (narrow-to-region (point) (point))
          (mh-insert-mime-security-button handle))
        (delete-region
         (point)
         (or (text-property-not-all
              (point) (point-max)
              'mh-line-format mh-mime-security-button-line-format)
             (point-max)))
        (forward-line -1)))))

(defun mh-mime-security-press-button (handle)
  "Callback from security button for part HANDLE."
  (when (mm-handle-multipart-ctl-parameter handle 'gnus-info)
    (mh-mime-security-show-details handle)))

;; These variables should already be initialized in mm-decode.el if we have a
;; recent enough Gnus. The defvars are here to avoid compiler warnings.
(defvar mm-verify-function-alist nil)
(defvar mm-decrypt-function-alist nil)

(defvar pressed-details)

(defun mh-insert-mime-security-button (handle)
  "Display buttons for PGP message, HANDLE."
  (let* ((protocol (mm-handle-multipart-ctl-parameter handle 'protocol))
         (crypto-type (or (nth 2 (assoc protocol mm-verify-function-alist))
                          (nth 2 (assoc protocol mm-decrypt-function-alist))
                          "Unknown"))
         (type (concat crypto-type
                       (if (equal (car handle) "multipart/signed")
                           " Signed" " Encrypted")
                       " Part"))
         (info (or (mm-handle-multipart-ctl-parameter handle 'gnus-info)
                   "Undecided"))
         (details (mm-handle-multipart-ctl-parameter handle 'gnus-details))
         pressed-details begin end)
    (setq details (if details (concat "\n" details) ""))
    (setq pressed-details (if mh-mime-security-button-pressed details ""))
    (unless (bolp) (insert "\n"))
    (setq begin (point))
    (gnus-eval-format
     mh-mime-security-button-line-format
     mh-mime-security-button-line-format-alist
     `(,@(gnus-local-map-property mh-mime-security-button-map)
         mh-button-pressed ,mh-mime-security-button-pressed
         mh-callback mh-mime-security-press-button
         mh-line-format ,mh-mime-security-button-line-format
         mh-data ,handle))
    (setq end (point))
    (widget-convert-button 'link begin end
                           :mime-handle handle
                           :action 'mh-widget-press-button
                           :button-keymap mh-mime-security-button-map
                           :help-echo "Mouse-2 click or press RET (in show buffer) to see security details.")
    (when (equal info "Failed")
      (let* ((type (if (equal (car handle) "multipart/signed")
                       "verification" "decryption"))
             (warning (if (equal type "decryption")
                          "(passphrase may be incorrect)" "")))
        (message "%s %s failed %s" crypto-type type warning)))))

(defun mh-mm-inline-message (handle)
  "Display message, HANDLE.
The function decodes the message and displays it. It avoids decoding the same
message multiple times."
  (let ((b (point))
        (clean-message-header mh-clean-message-header-flag)
        (invisible-headers mh-invisible-headers)
        (visible-headers mh-visible-headers))
    (save-excursion
      (save-restriction
        (narrow-to-region b b)
        (mm-insert-part handle)
        (mh-mime-display
         (or (gethash handle (mh-mime-handles-cache (mh-buffer-data)))
             (setf (gethash handle (mh-mime-handles-cache (mh-buffer-data)))
                   (let ((handles (or (mm-dissect-buffer nil)
                                      (mm-uu-dissect))))
                     (setf (mh-mime-handles (mh-buffer-data))
                           (mm-merge-handles
                            handles (mh-mime-handles (mh-buffer-data))))
                     handles))))

        (goto-char (point-min))
        (cond (clean-message-header
               (mh-clean-msg-header (point-min)
                                    invisible-headers
                                    visible-headers)
               (goto-char (point-min)))
              (t
               (mh-start-of-uncleaned-message)))
        (mh-show-xface)
        (mh-show-addr)
        ;; The other highlighting types don't need anything special
        (when (eq mh-highlight-citation-p 'gnus)
          (mh-gnus-article-highlight-citation))
        (goto-char (point-min))
        (insert "\n------- Forwarded Message\n\n")
        (mh-display-smileys)
        (mh-display-emphasis)
        (mm-handle-set-undisplayer
         handle
         `(lambda ()
            (let (buffer-read-only)
              (if (fboundp 'remove-specifier)
                  ;; This is only valid on XEmacs.
                  (mapcar (lambda (prop)
                            (remove-specifier
                             (face-property 'default prop) (current-buffer)))
                          '(background background-pixmap foreground)))
              (delete-region ,(point-min-marker) ,(point-max-marker)))))))))

(provide 'mh-mime)

;;; Local Variables:
;;; indent-tabs-mode: nil
;;; sentence-end-double-space: nil
;;; End:

;;; mh-mime.el ends here