* mh-alias.el (mh-alias-reload): Sync docstrings with manual.

[gnu-emacs] / lisp / mh-e / mh-e.el

;;; mh-e.el --- GNU Emacs interface to the MH mail system

;; Copyright (C) 1985, 1986, 1987, 1988,
;;  1990, 1992, 1993, 1994, 1995, 1997, 1999,
;;  2000, 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc.

;; Author: Bill Wohler <wohler@newt.com>
;; Maintainer: Bill Wohler <wohler@newt.com>
;; Version: 7.85+cvs
;; Keywords: mail

;; 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., 51 Franklin Street, Fifth Floor,
;; Boston, MA 02110-1301, USA.

;;; Commentary:

;; How to Use:
;;   M-x mh-rmail to read mail.  Type C-h m there for a list of commands.
;;   C-u M-x mh-rmail to visit any folder.
;;   M-x mh-smail to send mail.  From within the mail reader, "m" works, too.

;; Your .emacs might benefit from these bindings:
;;   (global-set-key "\C-cr" 'mh-rmail)
;;   (global-set-key "\C-xm" 'mh-smail)
;;   (global-set-key "\C-x4m" 'mh-smail-other-window)

;; MH (Message Handler) is a powerful mail reader.

;; The MH newsgroup is comp.mail.mh; the mailing list is mh-users@ics.uci.edu
;; (send to mh-users-request to be added). See the monthly Frequently Asked
;; Questions posting there for information on getting MH and MH-E:
;;   http://www.faqs.org/faqs/mail/mh-faq/part1/preamble.html

;; N.B. MH must have been compiled with the MHE compiler flag or several
;; features necessary for MH-E will be missing from MH commands, specifically
;; the -build switch to repl and forw.

;; MH-E is an Emacs interface to the MH mail system.

;; MH-E is supported in GNU Emacs 20 and 21, with MH 6.8.4 and nmh 1.0.4.

;; Mailing Lists:
;;   mh-e-users@lists.sourceforge.net
;;   mh-e-announce@lists.sourceforge.net
;;   mh-e-devel@lists.sourceforge.net
;;
;;   Subscribe by sending a "subscribe" message to
;;   <list>-request@lists.sourceforge.net, or by using the web interface at
;;   https://sourceforge.net/mail/?group_id=13357

;; Bug Reports:
;;   https://sourceforge.net/tracker/?group_id=13357&atid=113357
;;   Include the output of M-x mh-version in any bug report.

;; Feature Requests:
;;   https://sourceforge.net/tracker/?atid=363357&group_id=13357&func=browse

;; Support:
;;   https://sourceforge.net/tracker/?group_id=13357&atid=213357

;;; Change Log:

;; Original version for Gosling emacs by Brian Reid, Stanford, 1982.
;; Modified by James Larus, BBN, July 1984 and UCB, 1984 & 1985.
;; Rewritten for GNU Emacs, James Larus, 1985.
;; Modified by Stephen Gildea, 1988.
;; Maintenance picked up by Bill Wohler and the
;; SourceForge Crew <http://mh-e.sourceforge.net/>, 2001.

;;; Code:

(provide 'mh-e)

(eval-when-compile (require 'mh-acros))
(mh-require-cl)
(require 'mh-utils)
(require 'mh-init)
(require 'mh-inc)
(require 'mh-seq)
(require 'gnus-util)
(require 'easymenu)

;; Shush the byte-compiler
(defvar font-lock-auto-fontify)
(defvar font-lock-defaults)

(defconst mh-version "7.85+cvs" "Version number of MH-E.")

(defvar mh-partial-folder-mode-line-annotation "select"
  "Annotation when displaying part of a folder.
The string is displayed after the folder's name.  nil for no annotation.")

\f

;;; Scan Line Formats

;; Parameterize MH-E to work with different scan formats.  The defaults work
;; with the standard MH scan listings, in which the first 4 characters on
;; the line are the message number, followed by two places for notations.

;; The following scan formats are passed to the scan program if the setting of
;; `mh-scan-format-file' is t. They are identical except the later one makes
;; use of the nmh `decode' function to decode RFC 2047 encodings. If you just
;; want to change the column of the notations, use the `mh-set-cmd-note'
;; function.

(defvar mh-scan-format-mh
  (concat
   "%4(msg)"
   "%<(cur)+%| %>"
   "%<{replied}-"
   "%?(nonnull(comp{to}))%<(mymbox{to})t%>"
   "%?(nonnull(comp{cc}))%<(mymbox{cc})c%>"
   "%?(nonnull(comp{bcc}))%<(mymbox{bcc})b%>"
   "%?(nonnull(comp{newsgroups}))n%>"
   "%<(zero) %>"
   "%02(mon{date})/%02(mday{date})%<{date} %|*%>"
   "%<(mymbox{from})%<{to}To:%14(friendly{to})%>%>"
   "%<(zero)%17(friendly{from})%>  "
   "%{subject}%<{body}<<%{body}%>")
  "*Scan format string for MH.
This string is passed to the scan program via the -format argument.
This format is identical to the default except that additional hints for
fontification have been added to the fifth column (remember that in Emacs, the
first column is 0).

The values of the fifth column, in priority order, are: `-' if the message has
been replied to, t if an address on the To: line matches one of the
mailboxes of the current user, `c' if the Cc: line matches, `b' if the Bcc:
line matches, and `n' if a non-empty Newsgroups: header is present.")

(defvar mh-scan-format-nmh
  (concat
   "%4(msg)"
   "%<(cur)+%| %>"
   "%<{replied}-"
   "%?(nonnull(comp{to}))%<(mymbox{to})t%>"
   "%?(nonnull(comp{cc}))%<(mymbox{cc})c%>"
   "%?(nonnull(comp{bcc}))%<(mymbox{bcc})b%>"
   "%?(nonnull(comp{newsgroups}))n%>"
   "%<(zero) %>"
   "%02(mon{date})/%02(mday{date})%<{date} %|*%>"
   "%<(mymbox{from})%<{to}To:%14(decode(friendly{to}))%>%>"
   "%<(zero)%17(decode(friendly{from}))%>  "
   "%(decode{subject})%<{body}<<%{body}%>")
  "*Scan format string for nmh.
This string is passed to the scan program via the -format arg.
This format is identical to the default except that additional hints for
fontification have been added to the fifth column (remember that in Emacs, the
first column is 0).

The values of the fifth column, in priority order, are: `-' if the message has
been replied to, t if an address on the To: field matches one of the
mailboxes of the current user, `c' if the Cc: field matches, `b' if the Bcc:
field matches, and `n' if a non-empty Newsgroups: field is present.")

(defvar mh-note-deleted ?D
  "Messages that have been deleted are marked by this character.
See also `mh-scan-deleted-msg-regexp'.")

(defvar mh-note-refiled ?^
  "Messages that have been refiled are marked by this character.
See also `mh-scan-refiled-msg-regexp'.")

(defvar mh-note-cur ?+
  "The current message (in MH, not in MH-E) is marked by this character.
See also `mh-scan-cur-msg-number-regexp'.")

(defvar mh-scan-good-msg-regexp  "^\\( *[0-9]+\\)[^D^0-9]"
  "This regular expression matches \"good\" messages.
It must match from the beginning of the line. Note that the default setting of
`mh-folder-font-lock-keywords' expects this expression to contain at least one
parenthesized expression which matches the message number as in the default of
\"^\\\\( *[0-9]+\\\\)[^D^0-9]\". This expression includes the leading space
within the parenthesis since it looks better to highlight it as well. This
regular expression should be correct as it is needed by non-fontification
functions.")

(defvar mh-scan-deleted-msg-regexp "^\\( *[0-9]+\\)D"
  "This regular expression matches deleted messages.
It must match from the beginning of the line. Note that the default setting of
`mh-folder-font-lock-keywords' expects this expression to contain at least one
parenthesized expression which matches the message number as in the default of
\"^\\\\( *[0-9]+\\\\)D\". This expression includes the leading space within
the parenthesis since it looks better to highlight it as well. This regular
expression should be correct as it is needed by non-fontification functions.
See also `mh-note-deleted'.")

(defvar mh-scan-refiled-msg-regexp  "^\\( *[0-9]+\\)\\^"
  "This regular expression matches refiled messages.
It must match from the beginning of the line. Note that the default setting of
`mh-folder-font-lock-keywords' expects this expression to contain at least one
parenthesized expression which matches the message number as in the default of
\"^\\\\( *[0-9]+\\\\)\\\\^\". This expression includes the leading space
within the parenthesis since it looks better to highlight it as well. This
regular expression should be correct as it is needed by non-fontification
functions. See also `mh-note-refiled'.")

(defvar mh-scan-valid-regexp "^ *[0-9]"
  "This regular expression describes a valid scan line.
This is used to eliminate error messages that are occasionally produced by
\"inc\".")

(defvar mh-scan-cur-msg-number-regexp "^\\( *[0-9]+\\+\\).*"
  "This regular expression matches the current message.
It must match from the beginning of the line. Note that the default setting of
`mh-folder-font-lock-keywords' expects this expression to contain at least one
parenthesized expression which matches the message number as in the default of
\"^\\\\( *[0-9]+\\\\+\\\\).*\". This expression includes the leading space and
current message marker \"+\" within the parenthesis since it looks better to
highlight these items as well. This regular expression should be correct as it
is needed by non-fontification functions. See also `mh-note-cur'.")

(defvar mh-scan-date-regexp "\\([0-9][0-9]/[0-9][0-9]\\)"
  "This regular expression matches a valid date.
It must not be anchored to the beginning or the end of the line. Note that the
default setting of `mh-folder-font-lock-keywords' expects this expression to
contain only one parenthesized expression which matches the date field as in
the default of \"\\\\([0-9][0-9]/[0-9][0-9]\\\\)\"}. If this regular
expression is not correct, the date will not be highlighted. See also
`mh-scan-format-regexp'.")

(defvar mh-scan-rcpt-regexp  "\\(To:\\)\\(..............\\)"
  "This regular expression specifies the recipient in messages you sent.
Note that the default setting of `mh-folder-font-lock-keywords'
expects this expression to contain two parenthesized expressions. The
first is expected to match the `To:' that the default scan format
file generates. The second is expected to match the recipient's name
as in the default of \"\\\\(To:\\\\)\\\\(..............\\\\)\". If this
regular expression is not correct, the recipient will not be highlighted.")

(defvar mh-scan-body-regexp "\\(<<\\([^\n]+\\)?\\)"
  "This regular expression matches the message body fragment.
Note that the default setting of `mh-folder-font-lock-keywords' expects this
expression to contain at least one parenthesized expression which matches the
body text as in the default of \"\\\\(<<\\\\([^\\n]+\\\\)?\\\\)\". If this
regular expression is not correct, the body fragment will not be highlighted.")

(defvar mh-scan-subject-regexp
  "^ *[0-9]+........[ ]*...................\\([Rr][Ee]\\(\\[[0-9]+\\]\\)?:\\s-*\\)*\\([^<\n]*\\)"
  "This regular expression matches the subject.
It must match from the beginning of the line. Note that the default setting
of `mh-folder-font-lock-keywords' expects this expression to contain at least
three parenthesized expressions. The first is expected to match the `Re:'
string, if any. The second matches an optional bracketed number after `Re:',
such as in `Re[2]:' (and is thus a sub-expression of the first expression) and
the third is expected to match the subject line itself as in the default of
\(broken on multiple lines for readability):
  ^ *[0-9]+........[ ]*...................
  \\\\([Rr][Ee]\\\\(\\\\\\=[[0-9]+\\\\]\\\\)?:\\\\s-*\\\\)*
  \\\\([^<\\n]*\\\\)
This regular expression should be correct as it is needed by non-fontification
functions.")

(defvar mh-scan-format-regexp
  (concat "\\([bct]\\)" mh-scan-date-regexp " *\\(..................\\)")
  "This regular expression matches the output of scan.
Note that the default setting of `mh-folder-font-lock-keywords' expects this
expression to contain at least three parenthesized expressions. The first
should match the fontification hint (see `mh-scan-format-nmh'), the second is
found in `mh-scan-date-regexp', and the third should match the user name as in
the default of \"(concat \"\\\\([bct]\\\\)\" mh-scan-date-regexp
                         \"*\\\\(..................\\\\)\")\".
If this regular expression is not correct, the notation hints and the sender
will not be highlighted.")

\f

(defvar mh-folder-font-lock-keywords
  (list
   ;; Folders when displaying index buffer
   (list "^\\+.*"
         '(0 mh-index-folder-face))
   ;; Marked for deletion
   (list (concat mh-scan-deleted-msg-regexp ".*")
         '(0 mh-folder-deleted-face))
   ;; Marked for refile
   (list (concat mh-scan-refiled-msg-regexp ".*")
         '(0 mh-folder-refiled-face))
   ;;after subj
   (list mh-scan-body-regexp '(1 mh-folder-body-face nil t))
   '(mh-folder-font-lock-subject
     (1 mh-folder-followup-face append t)
     (2 mh-folder-subject-face append t))
   ;;current msg
   (list mh-scan-cur-msg-number-regexp
         '(1 mh-folder-cur-msg-number-face))
   (list mh-scan-good-msg-regexp
         '(1 mh-folder-msg-number-face)) ;; Msg number
   (list mh-scan-date-regexp '(1 mh-folder-date-face)) ;; Date
   (list mh-scan-rcpt-regexp
         '(1 mh-folder-to-face) ;; To:
         '(2 mh-folder-address-face)) ;; address
   ;; scan font-lock name
   (list mh-scan-format-regexp
         '(1 mh-folder-date-face)
         '(3 mh-folder-scan-format-face)))
  "Keywords (regular expressions) used to fontify the MH-Folder buffer.")

(defvar mh-scan-cmd-note-width 1
  "Number of columns consumed by the cmd-note field in `mh-scan-format'.
This column will have one of the values: ` ', `D', `^', `+' and where
` ' is the default value,
`D' is the `mh-note-deleted' character,
`^' is the `mh-note-refiled' character, and
`+' is the `mh-note-cur' character.")

(defvar mh-scan-destination-width 1
  "Number of columns consumed by the destination field in `mh-scan-format'.
This column will have one of ' ', '%', '-', 't', 'c', 'b', or `n' in it.
A ' ' blank space is the default character.
A '%' indicates that the message in in a named MH sequence.
A '-' indicates that the message has been annotated with a replied field.
A 't' indicates that the message contains mymbox in the To: field.
A 'c' indicates that the message contains mymbox in the Cc: field.
A 'b' indicates that the message contains mymbox in the Bcc: field.
A 'n' indicates that the message contains a Newsgroups: field.")

(defvar mh-scan-date-width 5
  "Number of columns consumed by the date field in `mh-scan-format'.
This column will typically be of the form mm/dd.")

(defvar mh-scan-date-flag-width 1
  "Number of columns consumed to flag (in)valid dates in `mh-scan-format'.
This column will have ` ' for valid and `*' for invalid or missing dates.")

(defvar mh-scan-from-mbox-width 17
  "Number of columns consumed with the \"From:\" line in `mh-scan-format'.
This column will have a friendly name or e-mail address of the
originator, or a \"To: address\" for outgoing e-mail messages.")

(defvar mh-scan-from-mbox-sep-width 2
  "Number of columns consumed by whitespace after from-mbox in `mh-scan-format'.
This column will only ever have spaces in it.")

(defvar mh-scan-field-destination-offset
  (+ mh-scan-cmd-note-width)
  "The offset from the `mh-cmd-note' for the destination column.")

(defvar mh-scan-field-from-start-offset
  (+ mh-scan-cmd-note-width
     mh-scan-destination-width
     mh-scan-date-width
     mh-scan-date-flag-width)
  "The offset from the `mh-cmd-note' to find the start of \"From:\" address.")

(defvar mh-scan-field-from-end-offset
  (+ mh-scan-field-from-start-offset mh-scan-from-mbox-width)
  "The offset from the `mh-cmd-note' to find the end of \"From:\" address.")

(defvar mh-scan-field-subject-start-offset
  (+ mh-scan-cmd-note-width
     mh-scan-destination-width
     mh-scan-date-width
     mh-scan-date-flag-width
     mh-scan-from-mbox-width
     mh-scan-from-mbox-sep-width)
  "The offset from the `mh-cmd-note' to find the start of the subject.")

(defun mh-folder-font-lock-subject (limit)
  "Return MH-E scan subject strings to font-lock between point and LIMIT."
  (if (not (re-search-forward mh-scan-subject-regexp limit t))
      nil
    (if (match-beginning 1)
        (set-match-data (list (match-beginning 1) (match-end 3)
                              (match-beginning 1) (match-end 3) nil nil))
      (set-match-data (list (match-beginning 3) (match-end 3)
                            nil nil (match-beginning 3) (match-end 3))))
    t))

\f

;; Fontifify unseen mesages in bold.

(defmacro mh-generate-sequence-font-lock (seq prefix face)
  "Generate the appropriate code to fontify messages in SEQ.
PREFIX is used to generate unique names for the variables and functions
defined by the macro. So a different prefix should be provided for every
invocation.
FACE is the font-lock face used to display the matching scan lines."
  (let ((cache (intern (format "mh-folder-%s-seq-cache" prefix)))
        (func (intern (format "mh-folder-font-lock-%s" prefix))))
    `(progn
       (defvar ,cache nil
         "Internal cache variable used for font-lock in MH-E.
Should only be non-nil through font-lock stepping, and nil once font-lock
is done highlighting.")
       (make-variable-buffer-local ',cache)

       (defun ,func (limit)
         "Return unseen message lines to font-lock between point and LIMIT."
         (if (not ,cache) (setq ,cache (mh-seq-msgs (mh-find-seq ,seq))))
         (let ((cur-msg (mh-get-msg-num nil)))
           (cond ((not ,cache)
                  nil)
                 ((>= (point) limit)              ;Presumably at end of buffer
                  (setq ,cache nil)
                  nil)
                 ((member cur-msg ,cache)
                  (let ((bpoint (progn (beginning-of-line)(point)))
                        (epoint (progn (forward-line 1)(point))))
                    (if (<= limit (point)) (setq  ,cache nil))
                    (set-match-data (list bpoint epoint bpoint epoint))
                    t))
                 (t
                  ;; move forward one line at a time, checking each message
                  (while (and (= 0 (forward-line 1))
                              (> limit (point))
                              (not (member (mh-get-msg-num nil) ,cache))))
                  ;; Examine how we must have exited the loop...
                  (let ((cur-msg (mh-get-msg-num nil)))
                    (cond ((or (<= limit (point))
                               (not (member cur-msg ,cache)))
                           (setq ,cache nil)
                           nil)
                          ((member cur-msg ,cache)
                           (let ((bpoint (progn (beginning-of-line) (point)))
                                 (epoint (progn (forward-line 1) (point))))
                             (if (<= limit (point)) (setq ,cache nil))
                             (set-match-data
                              (list bpoint epoint bpoint epoint))
                             t))))))))

       (setq mh-folder-font-lock-keywords
             (append mh-folder-font-lock-keywords
                     (list (list ',func (list 1 '',face 'prepend t))))))))

(mh-generate-sequence-font-lock mh-unseen-seq unseen bold)
(mh-generate-sequence-font-lock mh-tick-seq tick mh-folder-tick)

\f

;;; Internal variables:

(defvar mh-last-destination nil
  "Destination of last refile or write command.")

(defvar mh-last-destination-folder nil
  "Destination of last refile command.")

(defvar mh-last-destination-write nil
  "Destination of last write command.")

(defvar mh-folder-mode-map (make-keymap)
  "Keymap for MH folders.")

(defvar mh-arrow-marker nil
  "Marker for arrow display in fringe.")

(defvar mh-delete-list nil
  "List of message numbers to delete.
This variable can be used by `mh-before-commands-processed-hook'.")

(defvar mh-refile-list nil
  "List of folder names in `mh-seq-list'.
This variable can be used by `mh-before-commands-processed-hook'.")

(defvar mh-folders-changed nil
  "Lists which folders were affected by deletes and refiles.
This list will always include the current folder `mh-current-folder'.
This variable can be used by `mh-before-commands-processed-hook'.")

(defvar mh-next-direction 'forward
  "Direction to move to next message.")

(defvar mh-view-ops ()
  "Stack of operations that change the folder view.
These operations include narrowing or threading.")

(defvar mh-folder-view-stack ()
  "Stack of previous folder views.")

(defvar mh-index-data nil
  "Info about index search results.")

(defvar mh-index-previous-search nil)
(defvar mh-index-msg-checksum-map nil)
(defvar mh-index-checksum-origin-map nil)
(defvar mh-index-sequence-search-flag nil)

(defvar mh-first-msg-num nil
  "Number of first message in buffer.")

(defvar mh-last-msg-num nil
  "Number of last msg in buffer.")

(defvar mh-mode-line-annotation nil
  "Message range displayed in buffer.")

(defvar mh-sequence-notation-history nil
  "Remember original notation that is overwritten by `mh-note-seq'.")

(defvar mh-colors-available-flag nil
  "Non-nil means colors are available.")

\f

;;; Macros and generic functions:

(defun mh-mapc (function list)
  "Apply FUNCTION to each element of LIST for side effects only."
  (while list
    (funcall function (car list))
    (setq list (cdr list))))

(defun mh-scan-format ()
  "Return the output format argument for the scan program."
  (if (equal mh-scan-format-file t)
      (list "-format" (if (mh-variant-p 'nmh 'mu-mh)
                          (list (mh-update-scan-format
                                 mh-scan-format-nmh mh-cmd-note))
                        (list (mh-update-scan-format
                               mh-scan-format-mh mh-cmd-note))))
    (if (not (equal mh-scan-format-file nil))
        (list "-form" mh-scan-format-file))))

\f

;;; Entry points:

;;;###autoload
(defun mh-rmail (&optional arg)
  "Inc(orporate) new mail with MH.
Scan an MH folder if ARG is non-nil. This function is an entry point to MH-E,
the Emacs interface to the MH mail system."
  (interactive "P")
  (mh-find-path)
  (if arg
      (call-interactively 'mh-visit-folder)
    (unless (get-buffer mh-inbox)
      (mh-visit-folder mh-inbox (symbol-name mh-unseen-seq)))
    (mh-inc-folder)))

;;;###autoload
(defun mh-nmail (&optional arg)
  "Check for new mail in inbox folder.
Scan an MH folder if ARG is non-nil. This function is an entry point to MH-E,
the Emacs interface to the MH mail system."
  (interactive "P")
  (mh-find-path)                        ; init mh-inbox
  (if arg
      (call-interactively 'mh-visit-folder)
    (mh-visit-folder mh-inbox)))

\f

;;; User executable MH-E commands:

(defun mh-delete-msg (range)
  "Delete RANGE\\<mh-folder-mode-map>.

To mark a message for deletion, use this command. A \"D\" is placed by the
message in the scan window, and the next undeleted message is displayed. If
the previous command had been \\[mh-previous-undeleted-msg], then the next
message displayed is the first undeleted message previous to the message just
deleted. Use \\[mh-next-undeleted-msg] to force subsequent \\[mh-delete-msg]
commands to move forward to the next undeleted message after deleting the
message under the cursor.

The hook `mh-delete-msg-hook' is called after you mark a message for deletion.
For example, a past maintainer of MH-E used this once when he kept statistics
on his mail usage.

Check the documentation of `mh-interactive-range' to see how RANGE is read in
interactive use."
  (interactive (list (mh-interactive-range "Delete")))
  (mh-delete-msg-no-motion range)
  (if (looking-at mh-scan-deleted-msg-regexp)
      (mh-next-msg)))

(defun mh-delete-msg-no-motion (range)
  "Delete RANGE, don't move to next message.

This command marks the RANGE for deletion but leaves the cursor at the current
message in case you wish to perform other operations on the message.

Check the documentation of `mh-interactive-range' to see how RANGE is read in
interactive use."
  (interactive (list (mh-interactive-range "Delete")))
  (mh-iterate-on-range () range
    (mh-delete-a-msg nil)))

(defun mh-execute-commands ()
  "Process outstanding delete and refile requests\\<mh-folder-mode-map>.

If you've marked messages to be deleted or refiled and you want to go ahead
and delete or refile the messages, use this command. Many MH-E commands that
may affect the numbering of the messages (such as \\[mh-rescan-folder] or
\\[mh-pack-folder]) will ask if you want to process refiles or deletes first
and then either run this command for you or undo the pending refiles and
deletes, which are lost.

This function runs `mh-before-commands-processed-hook' before the commands are
processed and `mh-after-commands-processed-hook' after the commands are
processed."
  (interactive)
  (if mh-folder-view-stack (mh-widen t))
  (mh-process-commands mh-current-folder)
  (mh-set-scan-mode)
  (mh-goto-cur-msg)                    ; after mh-set-scan-mode for efficiency
  (mh-make-folder-mode-line)
  t)                                    ; return t for write-file-functions

(defun mh-first-msg ()
  "Display first message."
  (interactive)
  (goto-char (point-min))
  (while (and (not (eobp)) (not (looking-at mh-scan-valid-regexp)))
    (forward-line 1)))

(defun mh-header-display ()
  "Display message with all header fields\\<mh-folder-mode-map>.

Use the command \\[mh-show] to show the message normally again."
  (interactive)
  (and (not mh-showing-with-headers)
       (or mh-mhl-format-file mh-clean-message-header-flag)
       (mh-invalidate-show-buffer))
  (let ((mh-decode-mime-flag nil)
        (mh-mhl-format-file nil)
        (mh-clean-message-header-flag nil))
    (mh-show-msg nil)
    (mh-in-show-buffer (mh-show-buffer)
      (goto-char (point-min))
      (mh-recenter 0))
    (setq mh-showing-with-headers t)))

(defun mh-inc-folder (&optional maildrop-name folder)
  "Incorporate new mail into a folder.

You can incorporate mail from any file into the current folder by
specifying a prefix argument; you'll be prompted for the name of the
file to use as well as the destination folder

The hook `mh-inc-folder-hook' is run after incorporating new mail. Do
not call this function from outside MH-E; use \\[mh-rmail] instead.

In a program optional argument MAILDROP-NAME specifies an alternate
maildrop from the default. The optional argument FOLDER specifies
where to incorporate mail instead of the default named by `mh-inbox'."
  (interactive (list (if current-prefix-arg
                         (expand-file-name
                          (read-file-name "inc mail from file: "
                                          mh-user-path)))
                     (if current-prefix-arg
                         (mh-prompt-for-folder "inc mail into" mh-inbox t))))
  (if (not folder)
      (setq folder mh-inbox))
  (let ((threading-needed-flag nil))
    (let ((config (current-window-configuration)))
      (when (and mh-show-buffer (get-buffer mh-show-buffer))
        (delete-windows-on mh-show-buffer))
      (cond ((not (get-buffer folder))
             (mh-make-folder folder)
             (setq threading-needed-flag mh-show-threads-flag)
             (setq mh-previous-window-config config))
            ((not (eq (current-buffer) (get-buffer folder)))
             (switch-to-buffer folder)
             (setq mh-previous-window-config config))))
    (mh-get-new-mail maildrop-name)
    (when (and threading-needed-flag
               (save-excursion
                 (goto-char (point-min))
                 (or (null mh-large-folder)
                     (not (equal (forward-line (1+ mh-large-folder)) 0))
                     (and (message "Not threading since the number of messages exceeds `mh-large-folder'")
                          nil))))
      (mh-toggle-threads))
    (beginning-of-line)
    (if (and mh-showing-mode (looking-at mh-scan-valid-regexp)) (mh-show))
    (run-hooks 'mh-inc-folder-hook)))

(defun mh-last-msg ()
  "Display last message."
  (interactive)
  (goto-char (point-max))
  (while (and (not (bobp)) (not (looking-at mh-scan-valid-regexp)))
    (forward-line -1))
  (mh-recenter nil))

(defun mh-next-undeleted-msg (&optional count wait-after-complaining-flag)
  "Display next message.

This command can be given a prefix argument COUNT to specify how many unread
messages to skip.

In a program, pause for a second after printing message if we are at the last
undeleted message and optional argument WAIT-AFTER-COMPLAINING-FLAG is
non-nil."
  (interactive "p")
  (setq mh-next-direction 'forward)
  (forward-line 1)
  (cond ((re-search-forward mh-scan-good-msg-regexp nil t count)
         (beginning-of-line)
         (mh-maybe-show))
        (t (forward-line -1)
           (message "No more undeleted messages")
           (if wait-after-complaining-flag (sit-for 1)))))

(defun mh-folder-from-address ()
  "Derive folder name from sender.

The name of the folder is derived as follows:

  a) The folder name associated with the first address found in the list
     `mh-default-folder-list' is used. Each element in this list contains a
     `Check Recipient' item. If this item is turned on, then the address is
     checked against the recipient instead of the sender. This is useful for
     mailing lists.

  b) An alias prefixed by `mh-default-folder-prefix' corresponding to the
     address is used. The prefix is used to prevent clutter in your mail
     directory.

Return nil if a folder name was not derived, or if the variable
`mh-default-folder-must-exist-flag' is t and the folder does not exist."
  ;; Loop for all entries in mh-default-folder-list
  (save-restriction
    (goto-char (point-min))
    (re-search-forward "\n\n" nil 'limit)
    (narrow-to-region (point-min) (point))
    (let ((to/cc (concat (or (message-fetch-field "to") "") ", "
                         (or (message-fetch-field "cc") "")))
          (from (or (message-fetch-field "from") ""))
          folder-name)
      (setq folder-name
            (loop for list in mh-default-folder-list
                  when (string-match (nth 0 list) (if (nth 2 list) to/cc from))
                  return (nth 1 list)
                  finally return nil))

      ;; Make sure a result from `mh-default-folder-list' begins with "+"
      ;; since 'mh-expand-file-name below depends on it
      (when (and folder-name (not (eq (aref folder-name 0) ?+)))
        (setq folder-name (concat "+" folder-name)))

      ;; If not, is there an alias for the address?
      (when (not folder-name)
        (let* ((from-header (mh-extract-from-header-value))
               (address (and from-header
                             (nth 1 (mail-extract-address-components
                                     from-header))))
               (alias (and address (mh-alias-address-to-alias address))))
          (when alias
            (setq folder-name
                  (and alias (concat "+" mh-default-folder-prefix alias))))))

      ;; If mh-default-folder-must-exist-flag set, check that folder exists.
      (if (and folder-name
               (or (not mh-default-folder-must-exist-flag)
                   (file-exists-p (mh-expand-file-name folder-name))))
          folder-name))))

(defun mh-prompt-for-refile-folder ()
  "Prompt the user for a folder in which the message should be filed.
The folder is returned as a string.

The default folder name is generated by the option
`mh-default-folder-for-message-function' if it is non-nil or
`mh-folder-from-address'."
  (mh-prompt-for-folder
   "Destination"
   (let ((refile-file (ignore-errors (mh-msg-filename (mh-get-msg-num t)))))
     (if (null refile-file) ""
       (save-excursion
         (set-buffer (get-buffer-create mh-temp-buffer))
         (erase-buffer)
         (insert-file-contents refile-file)
         (or (and mh-default-folder-for-message-function
                  (let ((buffer-file-name refile-file))
                    (funcall mh-default-folder-for-message-function)))
             (mh-folder-from-address)
             (and (eq 'refile (car mh-last-destination-folder))
                  (symbol-name (cdr mh-last-destination-folder)))
             ""))))
   t))

(defun mh-refile-msg (range folder &optional dont-update-last-destination-flag)
  "Refile (output) RANGE into FOLDER.

You are prompted for the folder name. Note that this command can also be used
to create folders. If you specify a folder that does not exist, you will be
prompted to create it.

The hook `mh-refile-msg-hook' is called after a message is marked to be
refiled.

Check the documentation of `mh-interactive-range' to see how RANGE is read in
interactive use.

In a program, the variables `mh-last-destination' and
`mh-last-destination-folder' are not updated if
DONT-UPDATE-LAST-DESTINATION-FLAG is non-nil."
  (interactive (list (mh-interactive-range "Refile")
                     (intern (mh-prompt-for-refile-folder))))
  (unless dont-update-last-destination-flag
    (setq mh-last-destination (cons 'refile folder)
          mh-last-destination-folder mh-last-destination))
  (mh-iterate-on-range () range
    (mh-refile-a-msg nil folder))
  (when (looking-at mh-scan-refiled-msg-regexp) (mh-next-msg)))

(defun mh-refile-or-write-again (range &optional interactive-flag)
  "Repeat last output command.

If you are refiling several messages into the same folder, you can use this
command to repeat the last refile or write. You can use a range.

Check the documentation of `mh-interactive-range' to see how RANGE is read in
interactive use.

In a program, a non-nil INTERACTIVE-FLAG means that the function was called
interactively."
  (interactive (list (mh-interactive-range "Redo") t))
  (if (null mh-last-destination)
      (error "No previous refile or write"))
  (cond ((eq (car mh-last-destination) 'refile)
         (mh-refile-msg range (cdr mh-last-destination))
         (message "%s" (format "Destination folder: %s"
                               (cdr mh-last-destination))))
        (t
         (mh-iterate-on-range msg range
           (apply 'mh-write-msg-to-file msg (cdr mh-last-destination)))
         (mh-next-msg interactive-flag))))

(defun mh-quit ()
  "Quit the current MH-E folder.

When you want to quit using MH-E and go back to editing, you can use this
command. This buries the buffers of the current MH-E folder and restores the
buffers that were present when you first ran \\[mh-rmail]. It also removes any
MH-E working buffers whose name begins with \" *mh-\" or \"*MH-E \". You can
later restore your MH-E session by selecting the \"+inbox\" buffer or by
running \\[mh-rmail] again.

The two hooks `mh-before-quit-hook' and `mh-quit-hook' are called by this
function. The former one is called before the quit occurs, so you might use it
to perform any MH-E operations; you could perform some query and abort the
quit or call `mh-execute-commands', for example. The latter is not run in an
MH-E context, so you might use it to modify the window setup."
  (interactive)
  (run-hooks 'mh-before-quit-hook)
  (let ((show-buffer (get-buffer mh-show-buffer)))
    (when show-buffer
      (kill-buffer show-buffer)))
  (mh-update-sequences)
  (mh-destroy-postponed-handles)
  (bury-buffer (current-buffer))

  ;; Delete all MH-E temporary and working buffers.
  (dolist (buffer (buffer-list))
    (when (or (string-match "^ \\*mh-" (buffer-name buffer))
              (string-match "^\\*MH-E " (buffer-name buffer)))
      (kill-buffer buffer)))

  (if mh-previous-window-config
      (set-window-configuration mh-previous-window-config))
  (run-hooks 'mh-quit-hook))

(defun mh-page-msg (&optional lines)
  "Display next page in message.

You can give this command a prefix argument that specifies the number of LINES
to scroll. This command will also show the next undeleted message if it is
used at the bottom of a message."
  (interactive "P")
  (if mh-showing-mode
      (if mh-page-to-next-msg-flag
          (if (equal mh-next-direction 'backward)
              (mh-previous-undeleted-msg)
            (mh-next-undeleted-msg))
        (if (mh-in-show-buffer (mh-show-buffer)
              (pos-visible-in-window-p (point-max)))
            (progn
              (message
               "End of message (Type %s to read %s undeleted message)"
               (single-key-description last-input-event)
               (if (equal mh-next-direction 'backward)
                   "previous"
                 "next"))
              (setq mh-page-to-next-msg-flag t))
          (scroll-other-window lines)))
    (mh-show)))

(defun mh-previous-page (&optional lines)
  "Display next page in message.

You can give this command a prefix argument that specifies the number of LINES
to scroll."
  (interactive "P")
  (mh-in-show-buffer (mh-show-buffer)
    (scroll-down lines)))

(defun mh-previous-undeleted-msg (&optional count wait-after-complaining-flag)
  "Display previous message.

This command can be given a prefix argument COUNT to specify how many unread
messages to skip.

In a program, pause for a second after printing message if we are at the last
undeleted message and optional argument WAIT-AFTER-COMPLAINING-FLAG is
non-nil."
  (interactive "p")
  (setq mh-next-direction 'backward)
  (beginning-of-line)
  (cond ((re-search-backward mh-scan-good-msg-regexp nil t count)
         (mh-maybe-show))
        (t (message "No previous undeleted message")
           (if wait-after-complaining-flag (sit-for 1)))))

(defun mh-previous-unread-msg (&optional count)
  "Display previous unread message.

This command can be given a prefix argument COUNT to specify how many unread
messages to skip."
  (interactive "p")
  (unless (> count 0)
    (error "The function mh-previous-unread-msg expects positive argument"))
  (setq count (1- count))
  (let ((unread-sequence (cdr (assoc mh-unseen-seq mh-seq-list)))
        (cur-msg (mh-get-msg-num nil)))
    (cond ((and (not cur-msg) (not (bobp))
                ;; If we are at the end of the buffer back up one line and go
                ;; to unread message after that.
                (progn
                  (forward-line -1)
                  (setq cur-msg (mh-get-msg-num nil)))
                nil))
          ((or (null unread-sequence) (not cur-msg))
           ;; No unread message or there aren't any messages in buffer...
           (message "No more unread messages"))
          ((progn
             ;; Skip count messages...
             (while (and unread-sequence (>= (car unread-sequence) cur-msg))
               (setq unread-sequence (cdr unread-sequence)))
             (while (> count 0)
               (setq unread-sequence (cdr unread-sequence))
               (setq count (1- count)))
             (not (car unread-sequence)))
           (message "No more unread messages"))
          (t (loop for msg in unread-sequence
                   when (mh-goto-msg msg t) return nil
                   finally (message "No more unread messages"))))))

(defun mh-goto-next-button (backward-flag &optional criterion)
  "Search for next button satisfying criterion.
If BACKWARD-FLAG is non-nil search backward in the buffer for a mime button. If
CRITERION is a function or a symbol which has a function binding then that
function must return non-nil at the button we stop."
  (unless (or (and (symbolp criterion) (fboundp criterion))
              (functionp criterion))
    (setq criterion (lambda (x) t)))
  ;; Move to the next button in the buffer satisfying criterion
  (goto-char (or (save-excursion
                   (beginning-of-line)
                   ;; Find point before current button
                   (let ((point-before-current-button
                          (save-excursion
                            (while (get-text-property (point) 'mh-data)
                              (unless (= (forward-line
                                          (if backward-flag 1 -1))
                                         0)
                                (if backward-flag
                                    (goto-char (point-min))
                                  (goto-char (point-max)))))
                            (point))))
                     ;; Skip over current button
                     (while (and (get-text-property (point) 'mh-data)
                                 (not (if backward-flag (bobp) (eobp))))
                       (forward-line (if backward-flag -1 1)))
                     ;; Stop at next MIME button if any exists.
                     (block loop
                       (while (/= (progn
                                    (unless (= (forward-line
                                                (if backward-flag -1 1))
                                               0)
                                      (if backward-flag
                                          (goto-char (point-max))
                                        (goto-char (point-min)))
                                      (beginning-of-line))
                                    (point))
                                  point-before-current-button)
                         (when (and (get-text-property (point) 'mh-data)
                                    (funcall criterion (point)))
                           (return-from loop (point))))
                       nil)))
                 (point))))

(defun mh-next-button (&optional backward-flag)
  "Go to the next button.

If the end of the buffer is reached then the search wraps over to the start of
the buffer.

If an optional prefix argument BACKWARD-FLAG is given, the cursor will move to
the previous button."
  (interactive (list current-prefix-arg))
  (unless mh-showing-mode
    (mh-show))
  (mh-in-show-buffer (mh-show-buffer)
    (mh-goto-next-button backward-flag)))

(defun mh-prev-button ()
  "Go to the previous button.

If the beginning of the buffer is reached then the search wraps over to the
end of the buffer."
  (interactive)
  (mh-next-button t))

(defun mh-folder-mime-action (part-index action include-security-flag)
  "Go to PART-INDEX and carry out ACTION.
If PART-INDEX is nil then go to the next part in the buffer. The search for
the next buffer wraps around if end of buffer is reached. If argument
INCLUDE-SECURITY-FLAG is non-nil then include security info buttons when
searching for a suitable parts."
  (unless mh-showing-mode
    (mh-show))
  (mh-in-show-buffer (mh-show-buffer)
    (let ((criterion
           (cond (part-index
                  (lambda (p)
                    (let ((part (get-text-property p 'mh-part)))
                      (and (integerp part) (= part part-index)))))
                 (t (lambda (p)
                      (if include-security-flag
                          (get-text-property p 'mh-data)
                        (integerp (get-text-property p 'mh-part)))))))
          (point (point)))
      (cond ((and (get-text-property point 'mh-part)
                  (or (null part-index)
                      (= (get-text-property point 'mh-part) part-index)))
             (funcall action))
            ((and (get-text-property point 'mh-data)
                  include-security-flag
                  (null part-index))
             (funcall action))
            (t
             (mh-goto-next-button nil criterion)
             (if (= (point) point)
                 (message "No matching MIME part found")
               (funcall action)))))))

(defun mh-folder-toggle-mime-part (part-index)
  "View attachment.

This command displays (or hides) the attachment associated with the button
under the cursor. If the cursor is not located over a button, then the cursor
first moves to the next button, wrapping to the beginning of the message if
necessary. This command has the advantage over related commands of working
from the MH-Folder buffer.

You can also provide a numeric prefix argument PART-INDEX to view the
attachment labeled with that number. If Emacs does not know how to display the
attachment, then Emacs offers to save the attachment in a file."
  (interactive "P")
  (when (consp part-index) (setq part-index (car part-index)))
  (mh-folder-mime-action part-index #'mh-press-button t))

(defun mh-folder-inline-mime-part (part-index)
  "Show attachment verbatim.

You can view the raw contents of an attachment with this command. This command
displays (or hides) the contents of the attachment associated with the button
under the cursor verbatim. If the cursor is not located over a button, then
the cursor first moves to the next button, wrapping to the beginning of the
message if necessary.

You can also provide a numeric prefix argument PART-INDEX to view the
attachment labeled with that number."
  (interactive "P")
  (when (consp part-index) (setq part-index (car part-index)))
  (mh-folder-mime-action part-index #'mh-mime-inline-part nil))

(defun mh-folder-save-mime-part (part-index)
  "Save (output) attachment.

This command saves the attachment associated with the button under the cursor.
If the cursor is not located over a button, then the cursor first moves to the
next button, wrapping to the beginning of the message if necessary.

You can also provide a numeric prefix argument PART-INDEX to save the
attachment labeled with that number.

This command prompts you for a filename and suggests a specific name if it is
available."
  (interactive "P")
  (when (consp part-index) (setq part-index (car part-index)))
  (mh-folder-mime-action part-index #'mh-mime-save-part nil))

(defvar mh-thread-scan-line-map-stack)

(defun mh-reset-threads-and-narrowing ()
  "Reset all variables pertaining to threads and narrowing.
Also removes all content from the folder buffer."
  (setq mh-view-ops ())
  (setq mh-folder-view-stack ())
  (setq mh-thread-scan-line-map-stack ())
  (let ((buffer-read-only nil)) (erase-buffer)))

(defun mh-rescan-folder (&optional range dont-exec-pending)
  "Rescan folder\\<mh-folder-mode-map>.

This command is useful to grab all messages in your \"+inbox\" after
processing your new mail for the first time. If you don't want to rescan the
entire folder, this command will accept a RANGE. Check the documentation of
`mh-interactive-range' to see how RANGE is read in interactive use.

This command will ask if you want to process refiles or deletes first and then
either run \\[mh-execute-commands] for you or undo the pending refiles and
deletes, which are lost.

In a program, the processing of outstanding commands is not performed if
DONT-EXEC-PENDING is non-nil."
  (interactive (list (if current-prefix-arg
                         (mh-read-range "Rescan" mh-current-folder t nil t
                                        mh-interpret-number-as-range-flag)
                       nil)))
  (setq mh-next-direction 'forward)
  (let ((threaded-flag (memq 'unthread mh-view-ops)))
    (mh-scan-folder mh-current-folder (or range "all") dont-exec-pending)
    (cond (threaded-flag (mh-toggle-threads))
          (mh-index-data (mh-index-insert-folder-headers)))))

(defun mh-write-msg-to-file (message file no-header)
  "Append MESSAGE to end of FILE\\<mh-folder-mode-map>.

You are prompted for the filename. If the file already exists, the message is
appended to it. You can also write the message to the file without the header
by specifying a prefix argument NO-HEADER. Subsequent writes to the same file
can be made with the command \\[mh-refile-or-write-again]."
  (interactive
   (list (mh-get-msg-num t)
         (let ((default-dir (if (eq 'write (car mh-last-destination-write))
                                (file-name-directory
                                 (car (cdr mh-last-destination-write)))
                              default-directory)))
           (read-file-name (format "Save message%s in file: "
                                   (if current-prefix-arg " body" ""))
                           default-dir
                           (if (eq 'write (car mh-last-destination-write))
                               (car (cdr mh-last-destination-write))
                             (expand-file-name "mail.out" default-dir))))
         current-prefix-arg))
  (let ((msg-file-to-output (mh-msg-filename message))
        (output-file (mh-expand-file-name file)))
    (setq mh-last-destination (list 'write file (if no-header 'no-header))
          mh-last-destination-write mh-last-destination)
    (save-excursion
      (set-buffer (get-buffer-create mh-temp-buffer))
      (erase-buffer)
      (insert-file-contents msg-file-to-output)
      (goto-char (point-min))
      (if no-header (search-forward "\n\n"))
      (append-to-file (point) (point-max) output-file))))

(defun mh-toggle-showing ()
  "Toggle the scanning mode/showing mode of displaying messages."
  (interactive)
  (if mh-showing-mode
      (mh-set-scan-mode)
    (mh-show)))

(defun mh-undo (range)
  "Undo pending deletes or refiles in RANGE.

If you've deleted a message or refiled it, but changed your mind, you can
cancel the action before you've executed it. Use this command to undo a refile
on or deletion of a single message. You can also undo refiles and deletes for
messages that are found in a given RANGE.

Check the documentation of `mh-interactive-range' to see how RANGE is read in
interactive use."
  (interactive (list (mh-interactive-range "Undo")))
  (cond ((numberp range)
         (let ((original-position (point)))
           (beginning-of-line)
           (while (not (or (looking-at mh-scan-deleted-msg-regexp)
                           (looking-at mh-scan-refiled-msg-regexp)
                           (and (eq mh-next-direction 'forward) (bobp))
                           (and (eq mh-next-direction 'backward)
                                (save-excursion (forward-line) (eobp)))))
             (forward-line (if (eq mh-next-direction 'forward) -1 1)))
           (if (or (looking-at mh-scan-deleted-msg-regexp)
                   (looking-at mh-scan-refiled-msg-regexp))
               (progn
                 (mh-undo-msg (mh-get-msg-num t))
                 (mh-maybe-show))
             (goto-char original-position)
             (error "Nothing to undo"))))
        (t (mh-iterate-on-range () range
             (mh-undo-msg nil))))
  (if (not (mh-outstanding-commands-p))
      (mh-set-folder-modified-p nil)))


(defun mh-folder-line-matches-show-buffer-p ()
  "Return t if the message under point in folder-mode is in the show buffer.
Return nil in any other circumstance (no message under point, no show buffer,
the message in the show buffer doesn't match."
  (and (eq major-mode 'mh-folder-mode)
       (mh-get-msg-num nil)
       mh-show-buffer
       (get-buffer mh-show-buffer)
       (buffer-file-name (get-buffer mh-show-buffer))
       (string-match ".*/\\([0-9]+\\)$"
                     (buffer-file-name (get-buffer mh-show-buffer)))
       (string-equal
        (match-string 1 (buffer-file-name (get-buffer mh-show-buffer)))
        (int-to-string (mh-get-msg-num nil)))))

(eval-when-compile (require 'gnus))

(defmacro mh-macro-expansion-time-gnus-version ()
  "Return Gnus version available at macro expansion time.
The macro evaluates the Gnus version at macro expansion time. If MH-E was
compiled then macro expansion happens at compile time."
  gnus-version)

(defun mh-run-time-gnus-version ()
  "Return Gnus version available at run time."
  (require 'gnus)
  gnus-version)

;;;###autoload
(defun mh-version ()
  "Display version information about MH-E and the MH mail handling system."
  (interactive)
  (set-buffer (get-buffer-create mh-info-buffer))
  (erase-buffer)
  ;; MH-E version.
  (insert "MH-E " mh-version "\n\n")
  ;; MH-E compilation details.
  (insert "MH-E compilation details:\n")
  (let* ((compiled-mhe (byte-code-function-p (symbol-function 'mh-version)))
         (gnus-compiled-version (if compiled-mhe
                                    (mh-macro-expansion-time-gnus-version)
                                  "N/A")))
    (insert " Byte compiled:\t\t" (if compiled-mhe "yes" "no") "\n"
            " Gnus (compile-time):\t" gnus-compiled-version "\n"
            " Gnus (run-time):\t" (mh-run-time-gnus-version) "\n\n"))
  ;; Emacs version.
  (insert (emacs-version) "\n\n")
  ;; MH version.
  (if mh-variant-in-use
      (insert mh-variant-in-use "\n"
              " mh-progs:\t" mh-progs "\n"
              " mh-lib:\t" mh-lib "\n"
              " mh-lib-progs:\t" mh-lib-progs "\n\n")
    (insert "No MH variant detected\n"))
  ;; Linux version.
  (condition-case ()
      (call-process "uname" nil t nil "-a")
    (file-error))
  (goto-char (point-min))
  (display-buffer mh-info-buffer))

(defun mh-parse-flist-output-line (line &optional current-folder)
  "Parse LINE to generate folder name, unseen messages and total messages.
If CURRENT-FOLDER is non-nil then it contains the current folder name and it is
used to avoid problems in corner cases involving folders whose names end with a
'+' character."
  (with-temp-buffer
    (insert line)
    (goto-char (point-max))
    (let (folder unseen total p)
      (when (search-backward " out of " (point-min) t)
        (setq total (read-from-string
                     (buffer-substring-no-properties
                      (match-end 0) (line-end-position))))
        (when (search-backward " in sequence " (point-min) t)
          (setq p (point))
          (when (search-backward " has " (point-min) t)
            (setq unseen (read-from-string (buffer-substring-no-properties
                                            (match-end 0) p)))
            (while (eq (char-after) ? )
              (backward-char))
            (setq folder (buffer-substring-no-properties
                          (point-min) (1+ (point))))
            (when (and (equal (aref folder (1- (length folder))) ?+)
                       (equal current-folder folder))
              (setq folder (substring folder 0 (1- (length folder)))))
            (values (format "+%s" folder) (car unseen) (car total))))))))

(defun mh-folder-size-folder (folder)
  "Find size of FOLDER using `folder'."
  (with-temp-buffer
    (let ((u (length (cdr (assoc mh-unseen-seq
                                 (mh-read-folder-sequences folder nil))))))
      (call-process (expand-file-name "folder" mh-progs) nil t nil
                    "-norecurse" folder)
      (goto-char (point-min))
      (if (re-search-forward " has \\([0-9]+\\) " nil t)
          (values (car (read-from-string (match-string 1))) u folder)
        (values 0 u folder)))))

(defun mh-folder-size-flist (folder)
  "Find size of FOLDER using `flist'."
  (with-temp-buffer
    (call-process (expand-file-name "flist" mh-progs) nil t nil "-showzero"
                  "-norecurse" folder "-sequence" (symbol-name mh-unseen-seq))
    (goto-char (point-min))
    (multiple-value-bind (folder unseen total)
        (mh-parse-flist-output-line
         (buffer-substring (point) (line-end-position)))
      (values total unseen folder))))

(defun mh-folder-size (folder)
  "Find size of FOLDER."
  (if mh-flists-present-flag
      (mh-folder-size-flist folder)
    (mh-folder-size-folder folder)))

(defun mh-visit-folder (folder &optional range index-data)
  "Visit FOLDER.

When you want to read the messages that you have refiled into folders, use
this command to visit the folder. You are prompted for the folder name.

The folder buffer will show just unseen messages if there are any; otherwise,
it will show all the messages in the buffer as long there are fewer than
`mh-large-folder' messages. If there are more, then you are prompted for a
range of messages to scan.

You can provide a prefix argument in order to specify a RANGE of messages to
show when you visit the folder. In this case, regions are not used to specify
the range and `mh-large-folder' is ignored. Check the documentation of
`mh-interactive-range' to see how RANGE is read in interactive use.

Note that this command can also be used to create folders. If you specify a
folder that does not exist, you will be prompted to create it.

Do not call this function from outside MH-E; use \\[mh-rmail] instead.

If, in a program, RANGE is nil (the default), then all messages in FOLDER are
displayed. If an index buffer is being created then INDEX-DATA is used to
initialize the index buffer specific data structures."
  (interactive (let ((folder-name (mh-prompt-for-folder "Visit" mh-inbox t)))
                 (list folder-name
                       (mh-read-range "Scan" folder-name t nil
                                      current-prefix-arg
                                      mh-interpret-number-as-range-flag))))
  (let ((config (current-window-configuration))
        (current-buffer (current-buffer))
        (threaded-view-flag mh-show-threads-flag))
    (delete-other-windows)
    (save-excursion
      (when (get-buffer folder)
        (set-buffer folder)
        (setq threaded-view-flag (memq 'unthread mh-view-ops))))
    (when index-data
      (mh-make-folder folder)
      (setq mh-index-data (car index-data)
            mh-index-msg-checksum-map (make-hash-table :test #'equal)
            mh-index-checksum-origin-map (make-hash-table :test #'equal))
      (mh-index-update-maps folder (cadr index-data))
      (mh-index-create-sequences))
    (mh-scan-folder folder (or range "all"))
    (cond ((and threaded-view-flag
                (save-excursion
                  (goto-char (point-min))
                  (or (null mh-large-folder)
                      (not (equal (forward-line (1+ mh-large-folder)) 0))
                      (and (message "Not threading since the number of messages exceeds `mh-large-folder'")
                           nil))))
           (mh-toggle-threads))
          (mh-index-data
           (mh-index-insert-folder-headers)))
    (unless (eq current-buffer (current-buffer))
      (setq mh-previous-window-config config)))
  nil)


(defun mh-update-sequences ()
  "Flush MH-E's state out to MH.
This function updates the sequence specified by your \"Unseen-Sequence:\"
profile component, \"cur\", and the sequence listed by the `mh-tick-seq'
option which is \"tick\" by default. The message at the cursor is used for
\"cur\"."
  (interactive)
  ;; mh-update-sequences is the opposite of mh-read-folder-sequences,
  ;; which updates MH-E's state from MH.
  (let ((folder-set (mh-update-unseen))
        (new-cur (mh-get-msg-num nil)))
    (if new-cur
        (let ((seq-entry (mh-find-seq 'cur)))
          (mh-remove-cur-notation)
          (setcdr seq-entry
                  (list new-cur))       ;delete-seq-locally, add-msgs-to-seq
          (mh-define-sequence 'cur (list new-cur))
          (beginning-of-line)
          (if (looking-at mh-scan-good-msg-regexp)
              (mh-notate-cur)))
      (or folder-set
          (save-excursion
            ;; psg - mh-current-folder is nil if mh-summary-height < 4 !
            ;;       So I added this sanity check.
            (if (stringp mh-current-folder)
                (mh-exec-cmd-quiet t "folder" mh-current-folder "-fast")
              (mh-exec-cmd-quiet t "folder" "-fast")))))))

\f

;;; Support routines.

(defun mh-delete-a-msg (message)
  "Delete MESSAGE.
If MESSAGE is nil then the message at point is deleted.

The hook `mh-delete-msg-hook' is called after you mark a message for deletion.
For example, a past maintainer of MH-E used this once when he kept statistics
on his mail usage."
  (save-excursion
    (if (numberp message)
        (mh-goto-msg message nil t)
      (beginning-of-line)
      (setq message (mh-get-msg-num t)))
    (if (looking-at mh-scan-refiled-msg-regexp)
        (error "Message %d is refiled.  Undo refile before deleting" message))
    (if (looking-at mh-scan-deleted-msg-regexp)
        nil
      (mh-set-folder-modified-p t)
      (setq mh-delete-list (cons message mh-delete-list))
      (mh-notate nil mh-note-deleted mh-cmd-note)
      (run-hooks 'mh-delete-msg-hook))))

(defun mh-refile-a-msg (message folder)
  "Refile MESSAGE in FOLDER.
If MESSAGE is nil then the message at point is refiled.

Folder is a symbol, not a string.
The hook `mh-refile-msg-hook' is called after a message is marked to be
refiled."
  (save-excursion
    (if (numberp message)
        (mh-goto-msg message nil t)
      (beginning-of-line)
      (setq message (mh-get-msg-num t)))
    (cond ((looking-at mh-scan-deleted-msg-regexp)
           (error "Message %d is deleted.  Undo delete before moving" message))
          ((looking-at mh-scan-refiled-msg-regexp)
           (if (y-or-n-p
                (format "Message %d already refiled.  Copy to %s as well? "
                        message folder))
               (mh-exec-cmd "refile" (mh-get-msg-num t) "-link"
                            "-src" mh-current-folder
                            (symbol-name folder))
             (message "Message not copied")))
          (t
           (mh-set-folder-modified-p t)
           (cond ((null (assoc folder mh-refile-list))
                  (push (list folder message) mh-refile-list))
                 ((not (member message (cdr (assoc folder mh-refile-list))))
                  (push message (cdr (assoc folder mh-refile-list)))))
           (mh-notate nil mh-note-refiled mh-cmd-note)
           (run-hooks 'mh-refile-msg-hook)))))

(defun mh-next-msg (&optional wait-after-complaining-flag)
  "Move backward or forward to the next undeleted message in the buffer.
If optional argument WAIT-AFTER-COMPLAINING-FLAG is non-nil and we are at the
last message, then wait for a second after telling the user that there aren't
any more unread messages."
  (if (eq mh-next-direction 'forward)
      (mh-next-undeleted-msg 1 wait-after-complaining-flag)
    (mh-previous-undeleted-msg 1 wait-after-complaining-flag)))

(defun mh-next-unread-msg (&optional count)
  "Display next unread message.

This command can be given a prefix argument COUNT to specify how many unread
messages to skip."
  (interactive "p")
  (unless (> count 0)
    (error "The function mh-next-unread-msg expects positive argument"))
  (setq count (1- count))
  (let ((unread-sequence (reverse (cdr (assoc mh-unseen-seq mh-seq-list))))
        (cur-msg (mh-get-msg-num nil)))
    (cond ((and (not cur-msg) (not (bobp))
                ;; If we are at the end of the buffer back up one line and go
                ;; to unread message after that.
                (progn
                  (forward-line -1)
                  (setq cur-msg (mh-get-msg-num nil)))
                nil))
          ((or (null unread-sequence) (not cur-msg))
           ;; No unread message or there aren't any messages in buffer...
           (message "No more unread messages"))
          ((progn
             ;; Skip messages
             (while (and unread-sequence (>= cur-msg (car unread-sequence)))
               (setq unread-sequence (cdr unread-sequence)))
             (while (> count 0)
               (setq unread-sequence (cdr unread-sequence))
               (setq count (1- count)))
             (not (car unread-sequence)))
           (message "No more unread messages"))
          (t (loop for msg in unread-sequence
                   when (mh-goto-msg msg t) return nil
                   finally (message "No more unread messages"))))))

(defun mh-set-scan-mode ()
  "Display the scan listing buffer, but do not show a message."
  (if (get-buffer mh-show-buffer)
      (delete-windows-on mh-show-buffer))
  (mh-showing-mode 0)
  (force-mode-line-update)
  (if mh-recenter-summary-flag
      (mh-recenter nil)))

(defun mh-undo-msg (msg)
  "Undo the deletion or refile of one MSG.
If MSG is nil then act on the message at point"
  (save-excursion
    (if (numberp msg)
        (mh-goto-msg msg t t)
      (beginning-of-line)
      (setq msg (mh-get-msg-num t)))
    (cond ((memq msg mh-delete-list)
           (setq mh-delete-list (delq msg mh-delete-list)))
          (t
           (dolist (folder-msg-list mh-refile-list)
             (setf (cdr folder-msg-list) (remove msg (cdr folder-msg-list))))
           (setq mh-refile-list (loop for x in mh-refile-list
                                      unless (null (cdr x)) collect x))))
    (mh-notate nil ?  mh-cmd-note)))

\f

;;; The folder data abstraction.

(defvar mh-index-data-file ".mhe_index"
  "MH-E specific file where index seach info is stored.")

(defun mh-make-folder (name)
  "Create a new mail folder called NAME.
Make it the current folder."
  (switch-to-buffer name)
  (setq buffer-read-only nil)
  (erase-buffer)
  (if mh-adaptive-cmd-note-flag
      (mh-set-cmd-note (mh-msg-num-width-to-column (mh-msg-num-width name))))
  (setq buffer-read-only t)
  (mh-folder-mode)
  (mh-set-folder-modified-p nil)
  (setq buffer-file-name mh-folder-filename)
  (when (and (not mh-index-data)
             (file-exists-p (concat buffer-file-name mh-index-data-file)))
    (mh-index-read-data))
  (mh-make-folder-mode-line))

;; Ensure new buffers won't get this mode if default-major-mode is nil.
(put 'mh-folder-mode 'mode-class 'special)

\f

;;; Build mh-folder-mode menu

;; Menu extracted from mh-menubar.el V1.1 (31 July 2001)
;; Menus for folder mode: folder, message, sequence (in that order)
;; folder-mode "Sequence" menu
(easy-menu-define
  mh-folder-sequence-menu mh-folder-mode-map "Menu for MH-E folder-sequence."
  '("Sequence"
    ["Add Message to Sequence..."       mh-put-msg-in-seq (mh-get-msg-num nil)]
    ["List Sequences for Message"       mh-msg-is-in-seq (mh-get-msg-num nil)]
    ["Delete Message from Sequence..."  mh-delete-msg-from-seq
     (mh-get-msg-num nil)]
    ["List Sequences in Folder..."      mh-list-sequences t]
    ["Delete Sequence..."               mh-delete-seq t]
    ["Narrow to Sequence..."            mh-narrow-to-seq t]
    ["Widen from Sequence"              mh-widen mh-folder-view-stack]
    "--"
    ["Narrow to Subject Sequence"       mh-narrow-to-subject t]
    ["Narrow to Tick Sequence"          mh-narrow-to-tick
     (and mh-tick-seq (mh-seq-msgs (mh-find-seq mh-tick-seq)))]
    ["Delete Rest of Same Subject"      mh-delete-subject t]
    ["Toggle Tick Mark"                 mh-toggle-tick t]
    "--"
    ["Push State Out to MH"             mh-update-sequences t]))

;; folder-mode "Message" menu
(easy-menu-define
  mh-folder-message-menu mh-folder-mode-map "Menu for MH-E folder-message."
  '("Message"
    ["Show Message"                     mh-show (mh-get-msg-num nil)]
    ["Show Message with Header"         mh-header-display (mh-get-msg-num nil)]
    ["Next Message"                     mh-next-undeleted-msg t]
    ["Previous Message"                 mh-previous-undeleted-msg t]
    ["Go to First Message"              mh-first-msg t]
    ["Go to Last Message"               mh-last-msg t]
    ["Go to Message by Number..."       mh-goto-msg t]
    ["Modify Message"                   mh-modify t]
    ["Delete Message"                   mh-delete-msg (mh-get-msg-num nil)]
    ["Refile Message"                   mh-refile-msg (mh-get-msg-num nil)]
    ["Undo Delete/Refile"               mh-undo (mh-outstanding-commands-p)]
    ["Execute Delete/Refile"            mh-execute-commands
     (mh-outstanding-commands-p)]
    "--"
    ["Compose a New Message"            mh-send t]
    ["Reply to Message..."              mh-reply (mh-get-msg-num nil)]
    ["Forward Message..."               mh-forward (mh-get-msg-num nil)]
    ["Redistribute Message..."          mh-redistribute (mh-get-msg-num nil)]
    ["Edit Message Again"               mh-edit-again (mh-get-msg-num nil)]
    ["Re-edit a Bounced Message"        mh-extract-rejected-mail t]
    "--"
    ["Copy Message to Folder..."        mh-copy-msg (mh-get-msg-num nil)]
    ["Print Message"                    mh-print-msg (mh-get-msg-num nil)]
    ["Write Message to File..."         mh-write-msg-to-file
     (mh-get-msg-num nil)]
    ["Pipe Message to Command..."       mh-pipe-msg (mh-get-msg-num nil)]
    ["Unpack Uuencoded Message..."      mh-store-msg (mh-get-msg-num nil)]
    ["Burst Digest Message"             mh-burst-digest (mh-get-msg-num nil)]))

;; folder-mode "Folder" menu
(easy-menu-define
  mh-folder-folder-menu mh-folder-mode-map  "Menu for MH-E folder."
  '("Folder"
    ["Incorporate New Mail"             mh-inc-folder t]
    ["Toggle Show/Folder"               mh-toggle-showing t]
    ["Execute Delete/Refile"            mh-execute-commands
     (mh-outstanding-commands-p)]
    ["Rescan Folder"                    mh-rescan-folder t]
    ["Thread Folder"                    mh-toggle-threads
     (not (memq 'unthread mh-view-ops))]
    ["Pack Folder"                      mh-pack-folder t]
    ["Sort Folder"                      mh-sort-folder t]
    "--"
    ["List Folders"                     mh-list-folders t]
    ["Visit a Folder..."                mh-visit-folder t]
    ["View New Messages"                mh-index-new-messages t]
    ["Search a Folder..."               mh-search-folder t]
    ["Indexed Search..."                mh-index-search t]
    "--"
    ["Quit MH-E"                        mh-quit t]))

\f

(defmacro mh-remove-xemacs-horizontal-scrollbar ()
  "Get rid of the horizontal scrollbar that XEmacs insists on putting in."
  (when mh-xemacs-flag
    `(if (and (featurep 'scrollbar)
              (fboundp 'set-specifier))
         (set-specifier horizontal-scrollbar-visible-p nil
                        (cons (current-buffer) nil)))))

(defmacro mh-write-file-functions-compat ()
  "Return `write-file-functions' if it exists.
Otherwise return `local-write-file-hooks'. This macro exists purely for
compatibility. The former symbol is used in Emacs 21.4 onward while the latter
is used in previous versions and XEmacs."
  (if (boundp 'write-file-functions)
      ''write-file-functions            ;Emacs 21.4
    ''local-write-file-hooks))          ;<Emacs 21.4, XEmacs

;; Avoid compiler warnings in non-bleeding edge versions of Emacs.
(eval-when-compile
  (defvar tool-bar-mode)
  (defvar tool-bar-map)
  (defvar desktop-save-buffer))         ;Emacs 21.4

;; Register mh-folder-mode as supporting which-function-mode...
(load "which-func" t t)
(when (and (boundp 'which-func-modes)
           (not (member 'mh-folder-mode which-func-modes)))
  (push 'mh-folder-mode which-func-modes))

(defvar mh-folder-buttons-init-flag nil)

;; Autoload cookie needed by desktop.el
;;;###autoload
(define-derived-mode mh-folder-mode fundamental-mode "MH-Folder"
  "Major MH-E mode for \"editing\" an MH folder scan listing.\\<mh-folder-mode-map>

You can show the message the cursor is pointing to, and step through the
messages.  Messages can be marked for deletion or refiling into another
folder; these commands are executed all at once with a separate command.

Options that control this mode can be changed with \\[customize-group];
specify the \"mh\" group. In particular, please see the `mh-scan-format-file'
option if you wish to modify scan's format.

When a folder is visited, the hook `mh-folder-mode-hook' is run.

Ranges
======
Many commands that operate on individual messages, such as `mh-forward' or
`mh-refile-msg' take a RANGE argument. This argument can be used in several
ways.

If you provide the prefix argument (\\[universal-argument]) to these commands,
then you will be prompted for the message range. This can be any valid MH
range which can include messages, sequences, and the abbreviations (described
in the mh(1) man page):

<num1>-<num2>
    Indicates all messages in the range <num1> to <num2>, inclusive. The range
    must be nonempty.

`<num>:N'
`<num>:+N'
`<num>:-N'
    Up to N messages beginning with (or ending with) message num. Num may be
    any of the predefined symbols: first, prev, cur, next or last.

`first:N'
`prev:N'
`next:N'
`last:N'
    The first, previous, next or last messages, if they exist.

`all'
    All of the messages.

For example, a range that shows all of these things is `1 2 3 5-10 last:5
unseen'.

If the option `transient-mark-mode' is set to t and you set a region in the
MH-Folder buffer, then the MH-E command will perform the operation on all
messages in that region.

\\{mh-folder-mode-map}"
  (mh-do-in-gnu-emacs
   (unless mh-folder-buttons-init-flag
     (mh-tool-bar-folder-buttons-init)
     (setq mh-folder-buttons-init-flag t)))
  (make-local-variable 'font-lock-defaults)
  (setq font-lock-defaults '(mh-folder-font-lock-keywords t))
  (make-local-variable 'desktop-save-buffer)
  (setq desktop-save-buffer t)
  (mh-make-local-vars
   'mh-colors-available-flag (mh-colors-available-p)
                                        ; Do we have colors available
   'mh-current-folder (buffer-name)     ; Name of folder, a string
   'mh-show-buffer (format "show-%s" (buffer-name)) ; Buffer that displays msgs
   'mh-folder-filename                  ; e.g. "/usr/foobar/Mail/inbox/"
   (file-name-as-directory (mh-expand-file-name (buffer-name)))
   'mh-display-buttons-for-inline-parts-flag
   mh-display-buttons-for-inline-parts-flag ; Allow for display of buttons to
                                        ; be  toggled.
   'mh-arrow-marker (make-marker)       ; Marker where arrow is displayed
   'overlay-arrow-position nil          ; Allow for simultaneous display in
   'overlay-arrow-string ">"            ;  different MH-E buffers.
   'mh-showing-mode nil                 ; Show message also?
   'mh-delete-list nil                  ; List of msgs nums to delete
   'mh-refile-list nil                  ; List of folder names in mh-seq-list
   'mh-seq-list nil                     ; Alist of (seq . msgs) nums
   'mh-seen-list nil                    ; List of displayed messages
   'mh-next-direction 'forward          ; Direction to move to next message
   'mh-view-ops ()                      ; Stack that keeps track of the order
                                        ; in which narrowing/threading has been
                                        ; carried out.
   'mh-folder-view-stack ()             ; Stack of previous views of the
                                        ; folder.
   'mh-index-data nil                   ; If the folder was created by a call
                                        ; to mh-index-search this contains info
                                        ; about the search results.
   'mh-index-previous-search nil        ; Previous folder and search-regexp
   'mh-index-msg-checksum-map nil       ; msg -> checksum map
   'mh-index-checksum-origin-map nil    ; checksum -> ( orig-folder, orig-msg )
   'mh-index-sequence-search-flag nil   ; folder resulted from sequence search
   'mh-first-msg-num nil                ; Number of first msg in buffer
   'mh-last-msg-num nil                 ; Number of last msg in buffer
   'mh-msg-count nil                    ; Number of msgs in buffer
   'mh-mode-line-annotation nil         ; Indicates message range
   'mh-sequence-notation-history (make-hash-table)
                                        ; Remember what is overwritten by
                                        ; mh-note-seq.
   'imenu-create-index-function 'mh-index-create-imenu-index
                                        ; Setup imenu support
   'mh-previous-window-config nil)      ; Previous window configuration
  (mh-remove-xemacs-horizontal-scrollbar)
  (setq truncate-lines t)
  (auto-save-mode -1)
  (setq buffer-offer-save t)
  (mh-make-local-hook (mh-write-file-functions-compat))
  (add-hook (mh-write-file-functions-compat) 'mh-execute-commands nil t)
  (make-local-variable 'revert-buffer-function)
  (make-local-variable 'hl-line-mode)   ; avoid pollution
  (mh-funcall-if-exists hl-line-mode 1)
  (setq revert-buffer-function 'mh-undo-folder)
  (or (assq 'mh-showing-mode minor-mode-alist)
      (setq minor-mode-alist
            (cons '(mh-showing-mode " Show") minor-mode-alist)))
  (easy-menu-add mh-folder-sequence-menu)
  (easy-menu-add mh-folder-message-menu)
  (easy-menu-add mh-folder-folder-menu)
  (set (make-local-variable 'tool-bar-map) mh-folder-tool-bar-map)
  (mh-funcall-if-exists mh-tool-bar-init :folder)
  (if (and mh-xemacs-flag
           font-lock-auto-fontify)
      (turn-on-font-lock)))             ; Force font-lock in XEmacs.

(defun mh-toggle-mime-buttons ()
  "Toggle option `mh-display-buttons-for-inline-parts-flag'."
  (interactive)
  (setq mh-display-buttons-for-inline-parts-flag
        (not mh-display-buttons-for-inline-parts-flag))
  (mh-show nil t))

(defun mh-colors-available-p ()
  "Check if colors are available in the Emacs being used."
  (or mh-xemacs-flag
      (let ((color-cells
             (or (ignore-errors (mh-funcall-if-exists display-color-cells))
                 (ignore-errors (mh-funcall-if-exists
                                 x-display-color-cells)))))
        (and (numberp color-cells) (>= color-cells 8)))))

(defun mh-colors-in-use-p ()
  "Check if colors are being used in the folder buffer."
  (and mh-colors-available-flag font-lock-mode))

(defun mh-make-local-vars (&rest pairs)
  "Initialize local variables according to the variable-value PAIRS."

  (while pairs
    (set (make-local-variable (car pairs)) (car (cdr pairs)))
    (setq pairs (cdr (cdr pairs)))))

(defun mh-restore-desktop-buffer (desktop-buffer-file-name
                                  desktop-buffer-name
                                  desktop-buffer-misc)
  "Restore an MH folder buffer specified in a desktop file.
When desktop creates a buffer, DESKTOP-BUFFER-FILE-NAME holds the file name to
visit, DESKTOP-BUFFER-NAME holds the desired buffer name, and
DESKTOP-BUFFER-MISC holds a list of miscellaneous info used by the
`desktop-buffer-handlers' functions."
  (mh-find-path)
  (mh-visit-folder desktop-buffer-name)
  (current-buffer))

;; desktop-buffer-mode-handlers appeared in Emacs 22.
(if (fboundp 'desktop-buffer-mode-handlers)
    (add-to-list 'desktop-buffer-mode-handlers
                 '(mh-folder-mode . mh-restore-desktop-buffer)))

(defun mh-scan-folder (folder range &optional dont-exec-pending)
  "Scan FOLDER over RANGE.

After the scan is performed, switch to the buffer associated with FOLDER.

Check the documentation of `mh-interactive-range' to see how RANGE is read in
interactive use.

The processing of outstanding commands is not performed if DONT-EXEC-PENDING
is non-nil."
  (when (stringp range)
    (setq range (delete "" (split-string range "[ \t\n]"))))
  (cond ((null (get-buffer folder))
         (mh-make-folder folder))
        (t
         (unless dont-exec-pending
           (mh-process-or-undo-commands folder)
           (mh-reset-threads-and-narrowing))
         (switch-to-buffer folder)))
  (mh-regenerate-headers range)
  (if (zerop (buffer-size))
      (if (equal range "all")
          (message "Folder %s is empty" folder)
        (message "No messages in %s, range %s" folder range))
    (mh-goto-cur-msg))
  (when (mh-outstanding-commands-p)
    (mh-notate-deleted-and-refiled)))

(defun mh-msg-num-width-to-column (width)
  "Return the column for notations given message number WIDTH.
Note that columns in Emacs start with 0.

If `mh-scan-format-file' is set to \"Use MH-E scan Format\" this means that
either `mh-scan-format-mh' or `mh-scan-format-nmh' are in use. This function
therefore assumes that the first column is empty (to provide room for the
cursor), the following WIDTH columns contain the message number, and the
column for notations comes after that."
  (if (eq mh-scan-format-file t)
      (max (1+ width) 2)
    (error "%s %s" "Can't call mh-msg-num-width-to-column"
           "when mh-scan-format-file is not t")))

(defun mh-set-cmd-note (column)
  "Set `mh-cmd-note' to COLUMN.
Note that columns in Emacs start with 0."
  (setq mh-cmd-note column))

(defun mh-regenerate-headers (range &optional update)
  "Scan folder over RANGE.
If UPDATE, append the scan lines, otherwise replace."
  (let ((folder mh-current-folder)
        (range (if (and range (atom range)) (list range) range))
        scan-start)
    (message "Scanning %s..." folder)
    (mh-remove-all-notation)
    (with-mh-folder-updating (nil)
      (if update
          (goto-char (point-max))
        (delete-region (point-min) (point-max))
        (if mh-adaptive-cmd-note-flag
            (mh-set-cmd-note (mh-msg-num-width-to-column (mh-msg-num-width
                                                          folder)))))
      (setq scan-start (point))
      (apply #'mh-exec-cmd-output
             mh-scan-prog nil
             (mh-scan-format)
             "-noclear" "-noheader"
             "-width" (window-width)
             folder range)
      (goto-char scan-start)
      (cond ((looking-at "scan: no messages in")
             (keep-lines mh-scan-valid-regexp)) ; Flush random scan lines
            ((looking-at (if (mh-variant-p 'mu-mh)
                             "scan: message set .* does not exist"
                           "scan: bad message list "))
             (keep-lines mh-scan-valid-regexp))
            ((looking-at "scan: "))     ; Keep error messages
            (t
             (keep-lines mh-scan-valid-regexp))) ; Flush random scan lines
      (setq mh-seq-list (mh-read-folder-sequences folder nil))
      (mh-notate-user-sequences)
      (or update
          (setq mh-mode-line-annotation
                (if (equal range '("all"))
                    nil
                  mh-partial-folder-mode-line-annotation)))
      (mh-make-folder-mode-line))
    (message "Scanning %s...done" folder)))

(defun mh-generate-new-cmd-note (folder)
  "Fix the `mh-cmd-note' value for this FOLDER.

After doing an `mh-get-new-mail' operation in this FOLDER, at least
one line that looks like a truncated message number was found.

Remove the text added by the last `mh-inc' command. It should be the messages
cur-last. Call `mh-set-cmd-note', adjusting the notation column with the width
of the largest message number in FOLDER.

Reformat the message number width on each line in the buffer and trim
the line length to fit in the window.

Rescan the FOLDER in the range cur-last in order to display the
messages that were removed earlier. They should all fit in the scan
line now with no message truncation."
  (save-excursion
    (let ((maxcol (1- (window-width)))
          (old-cmd-note mh-cmd-note)
          mh-cmd-note-fmt
          msgnum)
      ;; Nuke all of the lines just added by the last inc
      (delete-char (- (point-max) (point)))
      ;; Update the current buffer to reflect the new mh-cmd-note
      ;; value needed to display messages.
      (mh-set-cmd-note (mh-msg-num-width-to-column (mh-msg-num-width folder)))
      (setq mh-cmd-note-fmt (concat "%" (format "%d" mh-cmd-note) "d"))
      ;; Cleanup the messages that are in the buffer right now
      (goto-char (point-min))
      (cond ((memq 'unthread mh-view-ops)
             (mh-thread-add-spaces (- mh-cmd-note old-cmd-note)))
            (t (while (re-search-forward mh-scan-msg-number-regexp nil 0 1)
                 ;; reformat the number to fix in mh-cmd-note columns
                 (setq msgnum (string-to-number
                               (buffer-substring
                                (match-beginning 1) (match-end 1))))
                 (replace-match (format mh-cmd-note-fmt msgnum))
                 ;; trim the line to fix in the window
                 (end-of-line)
                 (let ((eol (point)))
                   (move-to-column maxcol)
                   (if (<= (point) eol)
                       (delete-char (- eol (point))))))))
      ;; now re-read the lost messages
      (goto-char (point-max))
      (prog1 (point)
        (mh-regenerate-headers "cur-last" t)))))

(defun mh-get-new-mail (maildrop-name)
  "Read new mail from MAILDROP-NAME into the current buffer.
Return in the current buffer."
  (let ((point-before-inc (point))
        (folder mh-current-folder)
        (new-mail-flag nil))
    (with-mh-folder-updating (t)
      (if maildrop-name
          (message "inc %s -file %s..." folder maildrop-name)
        (message "inc %s..." folder))
      (setq mh-next-direction 'forward)
      (goto-char (point-max))
      (mh-remove-cur-notation)
      (let ((start-of-inc (point)))
        (if maildrop-name
            ;; I think MH 5 used "-ms-file" instead of "-file",
            ;; which would make inc'ing from maildrops fail.
            (mh-exec-cmd-output mh-inc-prog nil folder
                                (mh-scan-format)
                                "-file" (expand-file-name maildrop-name)
                                "-width" (window-width)
                                "-truncate")
          (mh-exec-cmd-output mh-inc-prog nil
                              (mh-scan-format)
                              "-width" (window-width)))
        (if maildrop-name
            (message "inc %s -file %s...done" folder maildrop-name)
          (message "inc %s...done" folder))
        (goto-char start-of-inc)
        (cond ((save-excursion
                 (re-search-forward "^inc: no mail" nil t))
               (message "No new mail%s%s" (if maildrop-name " in " "")
                        (if maildrop-name maildrop-name "")))
              ((and (when mh-folder-view-stack
                      (let ((saved-text (buffer-substring-no-properties
                                         start-of-inc (point-max))))
                        (delete-region start-of-inc (point-max))
                        (unwind-protect (mh-widen t)
                          (mh-remove-cur-notation)
                          (goto-char (point-max))
                          (setq start-of-inc (point))
                          (insert saved-text)
                          (goto-char start-of-inc))))
                    nil))
              ((re-search-forward "^inc:" nil t) ; Error messages
               (error "Error incorporating mail"))
              ((and
                (equal mh-scan-format-file t)
                mh-adaptive-cmd-note-flag
                ;; Have we reached an edge condition?
                (save-excursion
                  (re-search-forward mh-scan-msg-overflow-regexp nil 0 1))
                (setq start-of-inc (mh-generate-new-cmd-note folder))
                nil))
              (t
               (setq new-mail-flag t)))
        (keep-lines mh-scan-valid-regexp) ; Flush random scan lines
        (let* ((sequences (mh-read-folder-sequences folder t))
               (new-cur (assoc 'cur sequences))
               (new-unseen (assoc mh-unseen-seq sequences)))
          (unless (assoc 'cur mh-seq-list)
            (push (list 'cur) mh-seq-list))
          (unless (assoc mh-unseen-seq mh-seq-list)
            (push (list mh-unseen-seq) mh-seq-list))
          (setcdr (assoc 'cur mh-seq-list) (cdr new-cur))
          (setcdr (assoc mh-unseen-seq mh-seq-list) (cdr new-unseen)))
        (when (equal (point-max) start-of-inc)
          (mh-notate-cur))
        (if new-mail-flag
            (progn
              (mh-make-folder-mode-line)
              (when (mh-speed-flists-active-p)
                (mh-speed-flists t mh-current-folder))
              (when (memq 'unthread mh-view-ops)
                (mh-thread-inc folder start-of-inc))
              (mh-goto-cur-msg))
          (goto-char point-before-inc))
        (mh-notate-user-sequences (cons start-of-inc (point-max)))))))

(defun mh-make-folder-mode-line (&optional ignored)
  "Set the fields of the mode line for a folder buffer.
The optional argument is now obsolete and IGNORED. It used to be used to pass
in what is now stored in the buffer-local variable `mh-mode-line-annotation'."
  (save-excursion
    (save-window-excursion
      (mh-first-msg)
      (let ((new-first-msg-num (mh-get-msg-num nil)))
        (when (or (not (memq 'unthread mh-view-ops))
                  (null mh-first-msg-num)
                  (null new-first-msg-num)
                  (< new-first-msg-num mh-first-msg-num))
          (setq mh-first-msg-num new-first-msg-num)))
      (mh-last-msg)
      (let ((new-last-msg-num (mh-get-msg-num nil)))
        (when (or (not (memq 'unthread mh-view-ops))
                  (null mh-last-msg-num)
                  (null new-last-msg-num)
                  (> new-last-msg-num mh-last-msg-num))
          (setq mh-last-msg-num new-last-msg-num)))
      (setq mh-msg-count (if mh-first-msg-num
                             (count-lines (point-min) (point-max))
                           0))
      (setq mode-line-buffer-identification
            (list (format "    {%%b%s} %s msg%s"
                          (if mh-mode-line-annotation
                              (format "/%s" mh-mode-line-annotation)
                            "")
                          (if (zerop mh-msg-count)
                              "no"
                            (format "%d" mh-msg-count))
                          (if (zerop mh-msg-count)
                              "s"
                            (cond ((> mh-msg-count 1)
                                   (format "s (%d-%d)" mh-first-msg-num
                                           mh-last-msg-num))
                                  (mh-first-msg-num
                                   (format " (%d)" mh-first-msg-num))
                                  (""))))))
      (mh-logo-display))))

(defun mh-add-sequence-notation (msg internal-seq-flag)
  "Add sequence notation to the MSG on the current line.
If INTERNAL-SEQ-FLAG is non-nil, then refontify the scan line if font-lock is
turned on."
  (with-mh-folder-updating (t)
    (save-excursion
      (beginning-of-line)
      (if internal-seq-flag
          (progn
            ;; Change the buffer so that if transient-mark-mode is active
            ;; and there is an active region it will get deactivated as in
            ;; the case of user sequences.
            (mh-notate nil nil mh-cmd-note)
            (when font-lock-mode
              (font-lock-fontify-region (point) (line-end-position))))
        (forward-char (+ mh-cmd-note mh-scan-field-destination-offset))
        (let ((stack (gethash msg mh-sequence-notation-history)))
          (setf (gethash msg mh-sequence-notation-history)
                (cons (char-after) stack)))
        (mh-notate nil mh-note-seq
                   (+ mh-cmd-note mh-scan-field-destination-offset))))))

(defun mh-remove-sequence-notation (msg internal-seq-flag &optional all)
  "Remove sequence notation from the MSG on the current line.
If INTERNAL-SEQ-FLAG is non-nil, then `font-lock' was used to highlight the
sequence. In that case, no notation needs to be removed. Otherwise the effect
of inserting `mh-note-seq' needs to be reversed.
If ALL is non-nil, then all sequence marks on the scan line are removed."
  (with-mh-folder-updating (t)
    ;; This takes care of internal sequences...
    (mh-notate nil nil mh-cmd-note)
    (unless internal-seq-flag
      ;; ... and this takes care of user sequences.
      (let ((stack (gethash msg mh-sequence-notation-history)))
        (while (and all (cdr stack))
          (setq stack (cdr stack)))
        (when stack
          (save-excursion
            (beginning-of-line)
            (forward-char (+ mh-cmd-note mh-scan-field-destination-offset))
            (delete-char 1)
            (insert (car stack))))
        (setf (gethash msg mh-sequence-notation-history) (cdr stack))))))

(defun mh-remove-cur-notation ()
  "Remove old cur notation."
  (let ((cur-msg (car (mh-seq-to-msgs 'cur))))
    (save-excursion
      (when (and cur-msg
                 (mh-goto-msg cur-msg t t)
                 (looking-at mh-scan-cur-msg-number-regexp))
        (mh-notate nil ?  mh-cmd-note)
        (setq overlay-arrow-position nil)))))

(defun mh-remove-all-notation ()
  "Remove all notations on all scan lines that MH-E introduces."
  (save-excursion
    (setq overlay-arrow-position nil)
    (goto-char (point-min))
    (mh-iterate-on-range msg (cons (point-min) (point-max))
      (mh-notate nil ?  mh-cmd-note)
      (mh-remove-sequence-notation msg nil t))
    (clrhash mh-sequence-notation-history)))


(defun mh-goto-cur-msg (&optional minimal-changes-flag)
  "Position the cursor at the current message.
When optional argument MINIMAL-CHANGES-FLAG is non-nil, the function doesn't
recenter the folder buffer."
  (let ((cur-msg (car (mh-seq-to-msgs 'cur))))
    (cond ((and cur-msg
                (mh-goto-msg cur-msg t t))
           (unless minimal-changes-flag
             (mh-notate-cur)
             (mh-recenter 0)
             (mh-maybe-show cur-msg)))
          (t
           (setq overlay-arrow-position nil)
           (message "No current message")))))

(defun mh-process-or-undo-commands (folder)
  "If FOLDER has outstanding commands, then either process or discard them.
Called by functions like `mh-sort-folder', so also invalidate show buffer."
  (set-buffer folder)
  (if (mh-outstanding-commands-p)
      (if (or mh-do-not-confirm-flag
              (y-or-n-p
               "Process outstanding deletes and refiles? "))
          (mh-process-commands folder)
        (set-buffer folder)
        (mh-undo-folder)))
  (mh-update-unseen)
  (mh-invalidate-show-buffer))

(defun mh-process-commands (folder)
  "Process outstanding commands for FOLDER.

This function runs `mh-before-commands-processed-hook' before the commands are
processed and `mh-after-commands-processed-hook' after the commands are
processed."
  (message "Processing deletes and refiles for %s..." folder)
  (set-buffer folder)
  (with-mh-folder-updating (nil)
    ;; Run the before hook -- the refile and delete lists are still valid
    (run-hooks 'mh-before-commands-processed-hook)

    ;; Update the unseen sequence if it exists
    (mh-update-unseen)

    (let ((redraw-needed-flag mh-index-data)
          (folders-changed (list mh-current-folder))
          (seq-map (and mh-refile-list mh-refile-preserves-sequences-flag
                        (mh-create-sequence-map mh-seq-list)))
          (dest-map (and mh-refile-list mh-refile-preserves-sequences-flag
                         (make-hash-table))))
      ;; Remove invalid scan lines if we are in an index folder and then remove
      ;; the real messages
      (when mh-index-data
        (mh-index-delete-folder-headers)
        (setq folders-changed
              (append folders-changed (mh-index-execute-commands))))

      ;; Then refile messages
      (mh-mapc #'(lambda (folder-msg-list)
                   (let* ((dest-folder (symbol-name (car folder-msg-list)))
                          (last (car (mh-translate-range dest-folder "last")))
                          (msgs (cdr folder-msg-list)))
                     (push dest-folder folders-changed)
                     (setq redraw-needed-flag t)
                     (apply #'mh-exec-cmd
                            "refile" "-src" folder dest-folder
                            (mh-coalesce-msg-list msgs))
                     (mh-delete-scan-msgs msgs)
                     ;; Preserve sequences in destination folder...
                     (when mh-refile-preserves-sequences-flag
                       (clrhash dest-map)
                       (loop for i from (1+ (or last 0))
                             for msg in (sort (copy-sequence msgs) #'<)
                             do (loop for seq-name in (gethash msg seq-map)
                                      do (push i (gethash seq-name dest-map))))
                       (maphash
                        #'(lambda (seq msgs)
                            ;; Can't be run in the background, since the
                            ;; current folder is changed by mark this could
                            ;; lead to a race condition with the next refile.
                            (apply #'mh-exec-cmd "mark"
                                   "-sequence" (symbol-name seq) dest-folder
                                   "-add" (mapcar #'(lambda (x) (format "%s" x))
                                                  (mh-coalesce-msg-list msgs))))
                        dest-map))))
               mh-refile-list)
      (setq mh-refile-list ())

      ;; Now delete messages
      (cond (mh-delete-list
             (setq redraw-needed-flag t)
             (apply 'mh-exec-cmd "rmm" folder
                    (mh-coalesce-msg-list mh-delete-list))
             (mh-delete-scan-msgs mh-delete-list)
             (setq mh-delete-list nil)))

      ;; Don't need to remove sequences since delete and refile do so.
      ;; Mark cur message
      (if (> (buffer-size) 0)
          (mh-define-sequence 'cur (list (or (mh-get-msg-num nil) "last"))))

      ;; Redraw folder buffer if needed
      (when (and redraw-needed-flag)
        (when (mh-speed-flists-active-p)
          (apply #'mh-speed-flists t folders-changed))
        (cond ((memq 'unthread mh-view-ops) (mh-thread-inc folder (point-max)))
              (mh-index-data (mh-index-insert-folder-headers))))

      (and (buffer-file-name (get-buffer mh-show-buffer))
           (not (file-exists-p (buffer-file-name (get-buffer mh-show-buffer))))
           ;; If "inc" were to put a new msg in this file,
           ;; we would not notice, so mark it invalid now.
           (mh-invalidate-show-buffer))

      (setq mh-seq-list (mh-read-folder-sequences mh-current-folder nil))
      (mh-remove-all-notation)
      (mh-notate-user-sequences)

      ;; Run the after hook -- now folders-changed is valid,
      ;; but not the lists of specific messages.
      (let ((mh-folders-changed folders-changed))
        (run-hooks 'mh-after-commands-processed-hook)))

    (message "Processing deletes and refiles for %s...done" folder)))

(defun mh-update-unseen ()
  "Synchronize the unseen sequence with MH.
Return non-nil iff the MH folder was set.
The hook `mh-unseen-updated-hook' is called after the unseen sequence
is updated."
  (if mh-seen-list
      (let* ((unseen-seq (mh-find-seq mh-unseen-seq))
             (unseen-msgs (mh-seq-msgs unseen-seq)))
        (if unseen-msgs
            (progn
              (mh-undefine-sequence mh-unseen-seq mh-seen-list)
              (run-hooks 'mh-unseen-updated-hook)
              (while mh-seen-list
                (setq unseen-msgs (delq (car mh-seen-list) unseen-msgs))
                (setq mh-seen-list (cdr mh-seen-list)))
              (setcdr unseen-seq unseen-msgs)
              t)                        ;since we set the folder
          (setq mh-seen-list nil)))))

(defun mh-delete-scan-msgs (msgs)
  "Delete the scan listing lines for MSGS."
  (save-excursion
    (while msgs
      (when (mh-goto-msg (car msgs) t t)
        (when (memq 'unthread mh-view-ops)
          (mh-thread-forget-message (car msgs)))
        (mh-delete-line 1))
      (setq msgs (cdr msgs)))))

(defun mh-outstanding-commands-p ()
  "Return non-nil if there are outstanding deletes or refiles."
  (save-excursion
    (when (eq major-mode 'mh-show-mode)
      (set-buffer mh-show-folder-buffer))
    (or mh-delete-list mh-refile-list)))

(defun mh-coalesce-msg-list (messages)
  "Given a list of MESSAGES, return a list of message number ranges.
This is the inverse of `mh-read-msg-list', which expands ranges.
Message lists passed to MH programs should be processed by this function
to avoid exceeding system command line argument limits."
  (let ((msgs (sort (copy-sequence messages) 'mh-greaterp))
        (range-high nil)
        (prev -1)
        (ranges nil))
    (while prev
      (if range-high
          (if (or (not (numberp prev))
                  (not (equal (car msgs) (1- prev))))
              (progn                    ;non-sequential, flush old range
                (if (eq prev range-high)
                    (setq ranges (cons range-high ranges))
                  (setq ranges (cons (format "%s-%s" prev range-high) ranges)))
                (setq range-high nil))))
      (or range-high
          (setq range-high (car msgs))) ;start new or first range
      (setq prev (car msgs))
      (setq msgs (cdr msgs)))
    ranges))

(defun mh-greaterp (msg1 msg2)
  "Return the greater of two message indicators MSG1 and MSG2.
Strings are \"smaller\" than numbers.
Valid values are things like \"cur\", \"last\", 1, and 1820."
  (if (numberp msg1)
      (if (numberp msg2)
          (> msg1 msg2)
        t)
    (if (numberp msg2)
        nil
      (string-lessp msg2 msg1))))

(defun mh-lessp (msg1 msg2)
  "Return the lesser of two message indicators MSG1 and MSG2.
Strings are \"smaller\" than numbers.
Valid values are things like \"cur\", \"last\", 1, and 1820."
  (not (mh-greaterp msg1 msg2)))

\f

;;; Basic sequence handling

(defun mh-delete-seq-locally (seq)
  "Remove MH-E's record of SEQ."
  (let ((entry (mh-find-seq seq)))
    (setq mh-seq-list (delq entry mh-seq-list))))

(defun mh-read-folder-sequences (folder save-refiles)
  "Read and return the predefined sequences for a FOLDER.
If SAVE-REFILES is non-nil, then keep the sequences
that note messages to be refiled."
  (let ((seqs ()))
    (cond (save-refiles
           (mh-mapc (function (lambda (seq) ; Save the refiling sequences
                                (if (mh-folder-name-p (mh-seq-name seq))
                                    (setq seqs (cons seq seqs)))))
                    mh-seq-list)))
    (save-excursion
      (if (eq 0 (mh-exec-cmd-quiet nil "mark" folder "-list"))
          (progn
            ;; look for name in line of form "cur: 4" or "myseq (private): 23"
            (while (re-search-forward "^[^: ]+" nil t)
              (setq seqs (cons (mh-make-seq (intern (buffer-substring
                                                     (match-beginning 0)
                                                     (match-end 0)))
                                            (mh-read-msg-list))
                               seqs)))
            (delete-region (point-min) (point))))) ; avoid race with
                                        ; mh-process-daemon
    seqs))

(defun mh-read-msg-list ()
  "Return a list of message numbers from point to the end of the line.
Expands ranges into set of individual numbers."
  (let ((msgs ())
        (end-of-line (save-excursion (end-of-line) (point)))
        num)
    (while (re-search-forward "[0-9]+" end-of-line t)
      (setq num (string-to-number (buffer-substring (match-beginning 0)
                                                    (match-end 0))))
      (cond ((looking-at "-")           ; Message range
             (forward-char 1)
             (re-search-forward "[0-9]+" end-of-line t)
             (let ((num2 (string-to-number
                          (buffer-substring (match-beginning 0)
                                            (match-end 0)))))
               (if (< num2 num)
                   (error "Bad message range: %d-%d" num num2))
               (while (<= num num2)
                 (setq msgs (cons num msgs))
                 (setq num (1+ num)))))
            ((not (zerop num))          ;"pick" outputs "0" to mean no match
             (setq msgs (cons num msgs)))))
    msgs))

(defun mh-notate-user-sequences (&optional range)
  "Mark user-defined sequences in RANGE.

Check the documentation of `mh-interactive-range' to see how RANGE is read in
interactive use; if nil all messages are notated."
  (unless range
    (setq range (cons (point-min) (point-max))))
  (let ((seqs mh-seq-list)
        (msg-hash (make-hash-table)))
    (dolist (seq seqs)
      (dolist (msg (mh-seq-msgs seq))
        (push (car seq) (gethash msg msg-hash))))
    (mh-iterate-on-range msg range
      (loop for seq in (gethash msg msg-hash)
            do (mh-add-sequence-notation msg (mh-internal-seq seq))))))

(defvar mh-internal-seqs '(answered cur deleted forwarded printed))

(defun mh-internal-seq (name)
  "Return non-nil if NAME is the name of an internal MH-E sequence."
  (or (memq name mh-internal-seqs)
      (eq name mh-unseen-seq)
      (and (mh-colors-in-use-p) mh-tick-seq (eq name mh-tick-seq))
      (eq name mh-previous-seq)
      (mh-folder-name-p name)))

(defun mh-valid-seq-p (name)
  "Return non-nil if NAME is a valid MH sequence name."
  (and (symbolp name)
       (string-match "^[a-zA-Z][a-zA-Z0-9]*$" (symbol-name name))))

(defun mh-delete-msg-from-seq (range sequence &optional internal-flag)
  "Delete RANGE from SEQUENCE.

Check the documentation of `mh-interactive-range' to see how RANGE is read in
interactive use.

In a program, non-nil INTERNAL-FLAG means do not inform MH of the change."
  (interactive (list (mh-interactive-range "Delete")
                     (mh-read-seq-default "Delete from" t)
                     nil))
  (let ((entry (mh-find-seq sequence))
        (user-sequence-flag (not (mh-internal-seq sequence)))
        (folders-changed (list mh-current-folder))
        (msg-list ()))
    (when entry
      (mh-iterate-on-range msg range
        (push msg msg-list)
        ;; Calling "mark" repeatedly takes too long. So we will pretend here
        ;; that we are just modifying an internal sequence...
        (when (memq msg (cdr entry))
          (mh-remove-sequence-notation msg (not user-sequence-flag)))
        (mh-delete-a-msg-from-seq msg sequence t))
      ;; ... and here we will "mark" all the messages at one go.
      (unless internal-flag (mh-undefine-sequence sequence msg-list))
      (when (and mh-index-data (not internal-flag))
        (setq folders-changed
              (append folders-changed
                      (mh-index-delete-from-sequence sequence msg-list))))
      (when (and (eq sequence mh-unseen-seq) (mh-speed-flists-active-p))
        (apply #'mh-speed-flists t folders-changed)))))

(defun mh-catchup (range)
  "Delete RANGE from the \"unseen\" sequence.

Check the documentation of `mh-interactive-range' to see how RANGE is read in
interactive use."
  (interactive (list (mh-interactive-range "Catchup"
                                           (cons (point-min) (point-max)))))
  (mh-delete-msg-from-seq range mh-unseen-seq))

(defun mh-delete-a-msg-from-seq (msg sequence internal-flag)
  "Delete MSG from SEQUENCE.
If INTERNAL-FLAG is non-nil, then do not inform MH of the change."
  (let ((entry (mh-find-seq sequence)))
    (when (and entry (memq msg (mh-seq-msgs entry)))
      (if (not internal-flag)
          (mh-undefine-sequence sequence (list msg)))
      (setcdr entry (delq msg (mh-seq-msgs entry))))))

(defun mh-undefine-sequence (seq msgs)
  "Remove from the SEQ the list of MSGS."
  (when (and (mh-valid-seq-p seq) msgs)
    (apply #'mh-exec-cmd "mark" mh-current-folder "-delete"
           "-sequence" (symbol-name seq) (mh-coalesce-msg-list msgs))))

(defun mh-define-sequence (seq msgs)
  "Define the SEQ to contain the list of MSGS.
Do not mark pseudo-sequences or empty sequences.
Signals an error if SEQ is an invalid name."
  (if (and msgs
           (mh-valid-seq-p seq)
           (not (mh-folder-name-p seq)))
      (save-excursion
        (mh-exec-cmd-error nil "mark" mh-current-folder "-add" "-zero"
                           "-sequence" (symbol-name seq)
                           (mh-coalesce-msg-list msgs)))))

(defun mh-seq-containing-msg (msg &optional include-internal-flag)
  "Return a list of the sequences containing MSG.
If INCLUDE-INTERNAL-FLAG non-nil, include MH-E internal sequences in list."
  (let ((l mh-seq-list)
        (seqs ()))
    (while l
      (and (memq msg (mh-seq-msgs (car l)))
           (or include-internal-flag
               (not (mh-internal-seq (mh-seq-name (car l)))))
           (setq seqs (cons (mh-seq-name (car l)) seqs)))
      (setq l (cdr l)))
    seqs))

\f

;;; Build mh-folder-mode keymap:

(suppress-keymap mh-folder-mode-map)

;; Use defalias to make sure the documented primary key bindings
;; appear in menu lists.
(defalias 'mh-alt-show 'mh-show)
(defalias 'mh-alt-refile-msg 'mh-refile-msg)
(defalias 'mh-alt-send 'mh-send)
(defalias 'mh-alt-visit-folder 'mh-visit-folder)

;; Save the `b' binding for a future `back'. Maybe?
(gnus-define-keys  mh-folder-mode-map
  " "           mh-page-msg
  "!"           mh-refile-or-write-again
  "'"           mh-toggle-tick
  ","           mh-header-display
  "."           mh-alt-show
  ";"           mh-toggle-mh-decode-mime-flag
  ">"           mh-write-msg-to-file
  "?"           mh-help
  "E"           mh-extract-rejected-mail
  "M"           mh-modify
  "\177"        mh-previous-page
  "\C-d"        mh-delete-msg-no-motion
  "\t"          mh-index-next-folder
  [backtab]     mh-index-previous-folder
  "\M-\t"       mh-index-previous-folder
  "\e<"         mh-first-msg
  "\e>"         mh-last-msg
  "\ed"         mh-redistribute
  "\r"          mh-show
  "^"           mh-alt-refile-msg
  "c"           mh-copy-msg
  "d"           mh-delete-msg
  "e"           mh-edit-again
  "f"           mh-forward
  "g"           mh-goto-msg
  "i"           mh-inc-folder
  "k"           mh-delete-subject-or-thread
  "m"           mh-alt-send
  "n"           mh-next-undeleted-msg
  "\M-n"        mh-next-unread-msg
  "o"           mh-refile-msg
  "p"           mh-previous-undeleted-msg
  "\M-p"        mh-previous-unread-msg
  "q"           mh-quit
  "r"           mh-reply
  "s"           mh-send
  "t"           mh-toggle-showing
  "u"           mh-undo
  "v"           mh-index-visit-folder
  "x"           mh-execute-commands
  "|"           mh-pipe-msg)

(gnus-define-keys (mh-folder-map "F" mh-folder-mode-map)
  "?"           mh-prefix-help
  "'"           mh-index-ticked-messages
  "S"           mh-sort-folder
  "c"           mh-catchup
  "f"           mh-alt-visit-folder
  "i"           mh-index-search
  "k"           mh-kill-folder
  "l"           mh-list-folders
  "n"           mh-index-new-messages
  "o"           mh-alt-visit-folder
  "p"           mh-pack-folder
  "q"           mh-index-sequenced-messages
  "r"           mh-rescan-folder
  "s"           mh-search-folder
  "u"           mh-undo-folder
  "v"           mh-visit-folder)

(define-key mh-folder-mode-map "I" mh-inc-spool-map)

(gnus-define-keys (mh-junk-map "J" mh-folder-mode-map)
  "?"           mh-prefix-help
  "b"           mh-junk-blacklist
  "w"           mh-junk-whitelist)

(gnus-define-keys (mh-ps-print-map "P" mh-folder-mode-map)
  "?"           mh-prefix-help
  "C"           mh-ps-print-toggle-color
  "F"           mh-ps-print-toggle-faces
  "f"           mh-ps-print-msg-file
  "l"           mh-print-msg
  "p"           mh-ps-print-msg)

(gnus-define-keys (mh-sequence-map "S" mh-folder-mode-map)
  "'"           mh-narrow-to-tick
  "?"           mh-prefix-help
  "d"           mh-delete-msg-from-seq
  "k"           mh-delete-seq
  "l"           mh-list-sequences
  "n"           mh-narrow-to-seq
  "p"           mh-put-msg-in-seq
  "s"           mh-msg-is-in-seq
  "w"           mh-widen)

(gnus-define-keys (mh-thread-map "T" mh-folder-mode-map)
  "?"           mh-prefix-help
  "u"           mh-thread-ancestor
  "p"           mh-thread-previous-sibling
  "n"           mh-thread-next-sibling
  "t"           mh-toggle-threads
  "d"           mh-thread-delete
  "o"           mh-thread-refile)

(gnus-define-keys (mh-limit-map "/" mh-folder-mode-map)
  "'"           mh-narrow-to-tick
  "?"           mh-prefix-help
  "c"           mh-narrow-to-cc
  "f"           mh-narrow-to-from
  "r"           mh-narrow-to-range
  "s"           mh-narrow-to-subject
  "t"           mh-narrow-to-to
  "w"           mh-widen)

(gnus-define-keys (mh-extract-map "X" mh-folder-mode-map)
  "?"           mh-prefix-help
  "s"           mh-store-msg            ;shar
  "u"           mh-store-msg)           ;uuencode

(gnus-define-keys (mh-digest-map "D" mh-folder-mode-map)
  " "           mh-page-digest
  "?"           mh-prefix-help
  "\177"        mh-page-digest-backwards
  "b"           mh-burst-digest)

(gnus-define-keys (mh-mime-map "K" mh-folder-mode-map)
  "?"           mh-prefix-help
  "a"           mh-mime-save-parts
  "e"           mh-display-with-external-viewer
  "i"           mh-folder-inline-mime-part
  "o"           mh-folder-save-mime-part
  "t"           mh-toggle-mime-buttons
  "v"           mh-folder-toggle-mime-part
  "\t"          mh-next-button
  [backtab]     mh-prev-button
  "\M-\t"       mh-prev-button)

(cond
 (mh-xemacs-flag
  (define-key mh-folder-mode-map [button2] 'mh-show-mouse))
 (t
  (define-key mh-folder-mode-map [mouse-2] 'mh-show-mouse)))

;; "C-c /" prefix is used in mh-folder-mode by pgp.el and mailcrypt

\f

;;; Help Messages

;; If you add a new prefix, add appropriate text to the nil key.
;;
;; In general, messages are grouped logically. Taking the main commands for
;; example, the first line is "ways to view messages," the second line is
;; "things you can do with messages", and the third is "composing" messages.
;;
;; When adding a new prefix, ensure that the help message contains "what" the
;; prefix is for. For example, if the word "folder" were not present in the
;; `F' entry, it would not be clear what these commands operated upon.
(defvar mh-help-messages
  '((nil "[i]nc, [.]show, [,]show all, [n]ext, [p]revious,\n"
         "[d]elete, [o]refile, e[x]ecute,\n"
         "[s]end, [r]eply,\n"
         "[;]toggle MIME decoding.\n"
         "Prefix characters:\n [F]older, [S]equence, [J]unk, MIME [K]eys,"
         "\n [T]hread, [/]limit, e[X]tract, [D]igest, [I]nc spools.")

    (?F "[l]ist; [v]isit folder;\n"
        "[n]ew messages; [']ticked messages; [s]earch; [i]ndexed search;\n"
        "[p]ack; [S]ort; [r]escan; [k]ill")
    (?P "[p]rint message to [f]ile; old-style [l]pr printing;\n"
        "Toggle printing of [C]olors, [F]aces")
    (?S "[p]ut message in sequence, [n]arrow, [']narrow to ticked, [w]iden,\n"
        "[s]equences, [l]ist,\n"
        "[d]elete message from sequence, [k]ill sequence")
    (?T "[t]oggle, [d]elete, [o]refile thread")
    (?/ "Limit to [c]c, [f]rom, [r]ange, [s]ubject, [t]o; [w]iden")
    (?X "un[s]har, [u]udecode message")
    (?D "[b]urst digest")
    (?K "[v]iew, [i]nline, [o]utput/save MIME part; save [a]ll parts; \n"
        "[TAB] next; [SHIFT-TAB] previous")
    (?J "[b]lacklist, [w]hitelist message"))
  "Key binding cheat sheet.

This is an associative array which is used to show the most common commands.
The key is a prefix char. The value is one or more strings which are
concatenated together and displayed in the minibuffer if ? is pressed after
the prefix character. The special key nil is used to display the
non-prefixed commands.

The substitutions described in `substitute-command-keys' are performed as
well.")

\f

(dolist (mess '("^Cursor not pointing to message$"
                "^There is no other window$"))
  (add-to-list 'debug-ignored-errors mess))

(provide 'mh-e)

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

;; arch-tag: cce884de-bd37-4104-9963-e4439d5ed22b
;;; mh-e.el ends here