;;; rmailsort.el --- Rmail: sort messages.

;; Copyright (C) 1990, 1993 Free Software Foundation, Inc.

;; Author: Masanobu UMEDA <umerin@mse.kyutech.ac.jp>
;; Version: $Header: /home/fsf/rms/e19/lisp/RCS/rmailsort.el,v 1.14 1993/05/26 20:28:11 rms Exp rms $
;; 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, 675 Mass Ave, Cambridge, MA 02139, USA.

;;; Code:

(require 'sort)

(autoload 'timezone-make-date-sortable "timezone")

;; Sorting messages in Rmail buffer

(defun rmail-sort-by-date (reverse)
  "Sort messages of current Rmail file by date.
If prefix argument REVERSE is non-nil, sort them in reverse order."
  (interactive "P")
  (rmail-sort-messages reverse
		       (function
			(lambda (msg)
			  (rmail-make-date-sortable
			   (rmail-fetch-field msg "Date"))))))

(defun rmail-sort-by-subject (reverse)
  "Sort messages of current Rmail file by subject.
If prefix argument REVERSE is non-nil, sort them in reverse order."
  (interactive "P")
  (rmail-sort-messages reverse
		       (function
			(lambda (msg)
			  (let ((key (or (rmail-fetch-field msg "Subject") ""))
				(case-fold-search t))
			    ;; Remove `Re:'
			    (if (string-match "^\\(re:[ \t]+\\)*" key)
				(substring key (match-end 0)) key))))))

(defun rmail-sort-by-author (reverse)
  "Sort messages of current Rmail file by author.
If prefix argument REVERSE is non-nil, sort them in reverse order."
  (interactive "P")
  (rmail-sort-messages reverse
		       (function
			(lambda (msg)
			  (downcase	;Canonical name
			   (mail-strip-quoted-names
			    (or (rmail-fetch-field msg "From")
				(rmail-fetch-field msg "Sender") "")))))))

(defun rmail-sort-by-recipient (reverse)
  "Sort messages of current Rmail file by recipient.
If prefix argument REVERSE is non-nil, sort them in reverse order."
  (interactive "P")
  (rmail-sort-messages reverse
		       (function
			(lambda (msg)
			  (downcase	;Canonical name
			   (mail-strip-quoted-names
			    (or (rmail-fetch-field msg "To")
				(rmail-fetch-field msg "Apparently-To") "")
			    ))))))

(defun rmail-sort-by-correspondent (reverse)
  "Sort messages of current Rmail file by other correspondent.
If prefix argument REVERSE is non-nil, sort them in reverse order."
  (interactive "P")
  (rmail-sort-messages reverse
		       (function
			(lambda (msg)
			  (rmail-select-correspondent
			   msg
			   '("From" "Sender" "To" "Apparently-To"))))))

(defun rmail-select-correspondent (msg fields)
  (let ((ans ""))
    (while (and fields (string= ans ""))
      (setq ans
	    (rmail-dont-reply-to
	     (mail-strip-quoted-names
	      (or (rmail-fetch-field msg (car fields)) ""))))
      (setq fields (cdr fields)))
    ans))

(defun rmail-sort-by-lines (reverse)
  "Sort messages of current Rmail file by number of lines.
If prefix argument REVERSE is non-nil, sort them in reverse order."
  (interactive "P")
  (rmail-sort-messages reverse
		       (function
			(lambda (msg)
			  (count-lines (rmail-msgbeg msgnum)
				       (rmail-msgend msgnum))))))

;; Basic functions

(defun rmail-sort-messages (reverse keyfun)
  "Sort messages of current Rmail file.
If 1st argument REVERSE is non-nil, sort them in reverse order.
2nd argument KEYFUN is called with a message number, and should return a key."
  (let ((buffer-read-only nil)
	(predicate nil)			;< or string-lessp
	(sort-lists nil))
    (message "Finding sort keys...")
    (widen)
    (let ((msgnum 1))
      (while (>= rmail-total-messages msgnum)
	(setq sort-lists
	      (cons (list (funcall keyfun msgnum) ;Make sorting key
			  (eq rmail-current-message msgnum) ;True if current
			  (aref rmail-message-vector msgnum)
			  (aref rmail-message-vector (1+ msgnum)))
		    sort-lists))
	(if (zerop (% msgnum 10))
	    (message "Finding sort keys...%d" msgnum))
	(setq msgnum (1+ msgnum))))
    (or reverse (setq sort-lists (nreverse sort-lists)))
    ;; Decide predicate: < or string-lessp
    (if (numberp (car (car sort-lists))) ;Is a key numeric?
	(setq predicate (function <))
      (setq predicate (function string-lessp)))
    (setq sort-lists
	  (sort sort-lists
		(function
		 (lambda (a b)
		   (funcall predicate (car a) (car b))))))
    (if reverse (setq sort-lists (nreverse sort-lists)))
    ;; Now we enter critical region.  So, keyboard quit is disabled.
    (message "Reordering messages...")
    (let ((inhibit-quit t)		;Inhibit quit
	  (current-message nil)
	  (msgnum 1)
	  (msginfo nil))
      ;; There's little hope that we can easily undo after that.
      (buffer-flush-undo (current-buffer))
      (goto-char (rmail-msgbeg 1))
      ;; To force update of all markers.
      (insert-before-markers ?Z)
      (backward-char 1)
      ;; Now reorder messages.
      (while sort-lists
	(setq msginfo (car sort-lists))
	;; Swap two messages.
	(insert-buffer-substring
	 (current-buffer) (nth 2 msginfo) (nth 3 msginfo))
	(delete-region  (nth 2 msginfo) (nth 3 msginfo))
	;; Is current message?
	(if (nth 1 msginfo)
	    (setq current-message msgnum))
	(setq sort-lists (cdr sort-lists))
	(if (zerop (% msgnum 10))
	    (message "Reordering messages...%d" msgnum))
	(setq msgnum (1+ msgnum)))
      ;; Delete the garbage inserted before.
      (delete-char 1)
      (setq quit-flag nil)
      (buffer-enable-undo)
      (rmail-set-message-counters)
      (rmail-show-message current-message))
    ))

(defun rmail-fetch-field (msg field)
  "Return the value of the header FIELD of MSG.
Arguments are MSG and FIELD."
  (save-restriction
    (widen)
    (let ((next (rmail-msgend msg)))
      (goto-char (rmail-msgbeg msg))
      (narrow-to-region (if (search-forward "\n*** EOOH ***\n" next t)
			    (point)
			  (forward-line 1)
			  (point))
			(progn (search-forward "\n\n" nil t) (point)))
      (mail-fetch-field field))))

(defun rmail-make-date-sortable (date)
  "Make DATE sortable using the function string-lessp."
  ;; Assume the default time zone is GMT.
  (timezone-make-date-sortable date "GMT" "GMT"))

(provide 'rmailsort)

;;; rmailsort.el ends here