;; todomode.el -- major mode for editing TODO list files

;; $Id: todomode.el,v 1.9 1997/08/06 08:12:03 os10000 Exp os10000 $

;; ---------------------------------------------------------------------------

;; Copyright (C) 1997 Oliver Seidel

;; Keywords: todo-mode

;; todomode.el 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.

;; todomode.el is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;; GNU General Public License for more details.

;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs; see the file COPYING.  If not, write to the
;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
;; Boston, MA 02111-1307, USA.

;; ---------------------------------------------------------------------------

;;
;; Quickstart Installation:
;; ========================
;;
;; To get this to work, make emacs execute the line
;;
;; (require 'todomode)				;; load the TODO package
;;
;; I would also recommend executing the following commands
;; so as to extend the bindings in your global keymap:
;;
;; (global-set-key "\C-ct" 'todo-show)		;; switch to TODO buffer
;; (global-set-key "\C-ci" 'todo-cmd-inst)	;; insert new item
;;
;;
;;
;; Description:
;; ============
;;
;; TODO is a major mode for EMACS which offers functionality to treat
;; most lines in one buffer as a list of items one has to do.  There
;; are facilities to add new items, which are categorised, to edit or
;; even delete items from the buffer.  The buffer contents are currently
;; compatible with the diary, so that the list of todo-items will show
;; up in the FANCY diary mode.
;;
;; Notice:  Besides the major mode, this file also exports the function
;; "todo-show" which will change to the one specific TODO file that has
;; been specified in the todo-file-do variable.  If this file does not
;; conform to the TODO mode conventions, the todo-show function will add
;; the appropriate header and footer.  I don't anticipate this to cause
;; much grief, but be warned, in case you attempt to read a plain text file.
;;
;;
;;
;; Operation:
;; ==========
;;
;; You will have the following facilities available:
;;
;; M-x todo-show              will enter the todo list screen, here type
;;
;; +                          to go to next category
;; -                          to go to previous category
;; e                          to edit the current entry
;; f                          to file the current entry, including a
;;                                                 comment and timestamp
;; i                          to insert a new entry
;; k                          to kill the current entry
;; l                          lower the current entry's priority
;; n                          for the next entry
;; p                          for the previous entry
;; q                          to save the list and exit the buffer
;; r                          raise current entryk's priority
;; s                          to save the list
;;
;; When you add a new entry, you are asked for the text and then for the
;; category.  I for example have categories for things that I want to do
;; in the office (like mail my mum), that I want to do in town (like buy
;; cornflakes) and things I want to do at home (move my suitcases).  The
;; categories can be selected with the cursor keys and if you type in the
;; name of a category which didn't exist before, an empty category of the
;; desired name will be added and filled with the new entry.
;;
;;
;;
;; Configuration:
;; ==============
;;
;; --- todo-prefix
;;
;; I would like to recommend that you use the prefix "*/*" (by
;; leaving the variable 'todo-prefix' untouched) so that the diary
;; displays each entry every day.
;;
;; To understand what I mean, please read the documentation that goes
;; with the calendar since that will tell you how you can set up the
;; fancy diary display and use the #include command to include your
;; todo list file as part of your diary.
;;
;;
;; --- todo-file-do
;;
;; This variable is fairly self-explanatory.  You have to store your TODO
;; list somewhere.  This variable tells the package where to go and find
;; this file.
;;
;;
;; --- todo-file-done
;;
;; Even when you're done, you may wish to retain the entries.  Given
;; that they're timestamped and you are offered to add a comment, this
;; can make a useful diary of past events.  It will even blend in with
;; the EMACS diary package.  So anyway, this variable holds the name
;; of the file for the filed todo-items.
;;
;;
;; --- todo-mode-hook
;;
;; Just like other modes, too, this mode offers to call your functions
;; before it goes about its business.  This variable will be inspected
;; for any functions you may wish to have called once the other TODO
;; mode preparations have been completed.
;;
;;
;; --- todo-ins-thresh
;;
;; Another nifty feature is the insertion accuracy.  If you have 8 items
;; in your TODO list, then you may get asked 4 questions by the binary
;; insertion algorithm.  However, you may not really have a need for such
;; accurate priorities amongst your TODO items.  If you now think about
;; the binary insertion halfing the size of the window each time, then
;; the threshhold is the window size at which it will stop.  If you set
;; the threshhold to zero, the upper and lower bound will coincide at the
;; end of the loop and you will insert your item just before that point.
;; If you set the threshhold to i.e. 8, it will stop as soon as the window
;; size drops below that amount and will insert the item in the approximate
;; centre of that window.  I got the idea for this feature after reading
;; a very helpful e-mail reply from Trey Jackson <tjackson@ichips.intel.com>
;; who corrected some of my awful coding and pointed me towards some good
;; reading.  Thanks Trey!
;;
;;
;;
;; History and Gossip:
;; ===================
;;
;; Just for the case that you are wondering about the ugly name of this
;; package: I am one of those unfortunate people who have DOS, LINUX and
;; OS/2 on one of their computers, so part of my home-filespace is shared
;; and stored on a DOS partition, which is accessible to all systems.  If
;; you wish, you can of course rename the name of the file (and the "provide"
;; command near the end of this package) to something more aisthetically
;; (please don't argue about this spelling ...) pleasing, like i.e. todo-mode.
;;
;; Enjoy this package and express your gratitude by sending valuables
;; to my parents' address as listed above!!!
;;
;; Oliver Seidel
;;
;;
;;
;; Contact information:
;; ====================
;;
;; address ....:  O Seidel, Lessingstr 8, Eschborn, FRG
;; e-mail .....:  Oliver.Seidel@cl.cam.ac.uk (was valid on 2 Aug 1997)
;;

;; ---------------------------------------------------------------------------

;;
;; $Log: todomode.el,v $
;; Revision 1.9  1997/08/06 08:12:03  os10000
;; Improved documentation.  Broke some lines to comply with
;; Richard Stallman's email to please keep in sync with the
;; rest of the Emacs distribution files.
;;
;; Revision 1.8  1997/08/05 22:39:04  os10000
;; Made todomode.el available under GPL.
;;
;; Revision 1.7  1997/08/05 22:34:14  os10000
;; Fixed insertion routine with help from Trey Jackson
;; <tjackson@ichips.intel.com>; added todo-ins-thresh;
;; fixed keyboard layout to remove unwanted keys.
;;
;; Revision 1.6  1997/08/05 16:47:01  os10000
;; Incorporated menus for XEmacs from Allan.Cochrane@soton.sc.philips.com,
;; fixed TYPO, fixed todo-file-cmd, cleaned up rcs history.
;;
;; Revision 1.5  1997/08/05  14:43:39  os10000
;; Added improvements from Ron Gut <rgut@aware.com>.
;; Added category management.
;;
;; Revision 1.4  1997/08/04  16:18:45  os10000
;; Added Raise/Lower item.
;;
;; Revision 1.3  1997/08/03  12:47:26  os10000
;; Cleaned up variables, prefix and cursor position.
;;
;; Revision 1.2  1997/08/03 12:15:28  os10000
;; It appears to work.
;;
;; Revision 1.1  1997/08/03 12:15:13  os10000
;; Initial revision
;;

;; ---------------------------------------------------------------------------

;; User-configurable variables:

(defvar todo-prefix "*/*" "TODO mode prefix when creating entries")
(defvar todo-file-do "~/.todo-do" "TODO mode filename of list file")
(defvar todo-file-done "~/.todo-done" "TODO mode filename of archive file")
(defvar todo-mode-hook nil "Hooks invoked when the TODO mode is entered.")
(defvar todo-ins-thresh 0 "TODO mode insertion accuracy.")

;; ---------------------------------------------------------------------------

(require 'time-stamp)

(defvar todo-mode-map nil "TODO mode keymap.  See `todo-mode'")
(if todo-mode-map
    nil
  (let ((map (make-keymap)))
    (suppress-keymap map t)
    (define-key map "+" 'todo-cmd-forw)
    (define-key map "-" 'todo-cmd-back)
    (define-key map "e" 'todo-cmd-edit)
    (define-key map "f" 'todo-cmd-file)
    (define-key map "i" 'todo-cmd-inst)
    (define-key map "k" 'todo-cmd-kill)
    (define-key map "l" 'todo-cmd-lowr)
    (define-key map "n" 'todo-cmd-next)
    (define-key map "p" 'todo-cmd-prev)
    (define-key map "q" 'todo-cmd-done)
    (define-key map "r" 'todo-cmd-rais)
    (define-key map "s" 'todo-cmd-save)
    (setq todo-mode-map map)))

(defun todo-cat-slct ()
  (let ((todo-category-name (nth todo-category-number todo-cats)))
    (setq mode-line-buffer-identification
	  (concat "Category: " todo-category-name))
    (widen)
    (goto-char (point-min))
    (search-forward (concat "--- " todo-category-name))
    (setq begin (+ (point-at-eol) 1))
    (search-forward "--- End")
    (narrow-to-region begin (point-at-bol))
    (goto-char (point-min))
    )
)

(defun todo-cmd-forw () "Go forward to TODO list of next category."
  (interactive)
  (let ((todo-cat-cnt (- (length todo-cats) 1)))
    (setq todo-category-number (if (< todo-category-number todo-cat-cnt)
				   (+ todo-category-number 1) 0))
    (todo-cat-slct)
    )
  )

(defun todo-cmd-back () "Go back to TODO list of previous category."
  (interactive)
  (let ((todo-cat-cnt (- (length todo-cats) 1)))
    (setq todo-category-number (if (> todo-category-number 0)
				   (- todo-category-number 1) todo-cat-cnt))
    (todo-cat-slct)
    )
  )

(defun todo-cmd-prev () "Select previous entry of TODO list."
  (interactive)
  (forward-line -1)
  (beginning-of-line nil)
  (message "")
  )

(defun todo-cmd-next () "Select next entry of TODO list."
  (interactive)
  (forward-line 1)
  (beginning-of-line nil)
  (message "")
  )

(defun todo-cmd-save () "Save the TODO list."
  (interactive)
  (save-buffer)
  )

(defun todo-cmd-done () "Done with TODO list for now."
  (interactive)
  (widen)
  (save-buffer)
  (beginning-of-line nil)
  (message "")
  (bury-buffer)
  )

(defun todo-line () "Find current line in buffer."
  (buffer-substring (point-at-bol) (point-at-eol)))

(defun todo-cmd-edit () "Edit current TODO list entry."
  (interactive)
  (let ((todo-entry (read-from-minibuffer "Edit: " (todo-line))))
    (delete-region (point-at-bol) (point-at-eol))
    (insert todo-entry)
    (beginning-of-line nil)
    (message "")))

(defvar todo-prv-lne 0 "previous line that I asked about.")
(defvar todo-prv-ans 0 "previous answer that I got.")

(defun todo-add-category (cat) "Add a new category to the TODO list."
  (interactive)
  (save-window-excursion
    (setq todo-cats (cons cat todo-cats))
    (find-file todo-file-do)
    (widen)
    (goto-char (point-min))
    (let ((posn (search-forward "-*- mode: todo; " 17 t)))
      (if (not (null posn)) (goto-char posn))
      (if (equal posn nil)
	  (progn
	    (insert "-*- mode: todo; \n")
	    (forward-char -1))
	(kill-line)))
    (insert (format "todo-cats: %S; -*-" todo-cats))
    (forward-char 1)
    (insert (format "%s --- %s\n--- End\n%s %s\n"
		    todo-prefix cat todo-prefix (make-string 75 ?-)))
    )
  0
  )

(defun todo-cmd-inst ()
  "Insert new TODO list entry."
  (interactive)
  (beginning-of-line nil)
  (let* ((todo-entry (concat todo-prefix " "
			     (read-from-minibuffer "New TODO entry: ")))
         (temp-catgs todo-cats)
         (todo-hstry (cons 'temp-catgs (+ todo-category-number 1))))
    (save-window-excursion
      (setq todo-category
            (read-from-minibuffer "Category: "
                                  (nth todo-category-number todo-cats)
                                  nil nil todo-hstry))

      (let ((cat-exists (member todo-category todo-cats)))
        (setq todo-category-number
              (if cat-exists
                  (- (length todo-cats) (length cat-exists))
                (todo-add-category todo-category))))
      (todo-show)
      (setq todo-prv-lne 0)

      (let ((todo-fst 1)
            (todo-lst (+ 1 (count-lines (point-min) (point-max)))))
        (while (> (- todo-lst todo-fst) todo-ins-thresh)
          (let* ((todo-cur (/ (+ todo-fst todo-lst) 2))
                 (todo-ans (if (< todo-cur todo-lst)
			       (todo-ask todo-cur) nil)))
            (if todo-ans
                (setq todo-lst todo-cur)
              (setq todo-fst (+ todo-cur 1)))))

	(setq todo-fst (/ (+ todo-fst todo-lst) 2))
        ;; goto-line doesn't have the desired behavior in a narrowed buffer
        (goto-char (point-min))
	(message (format "todo-fst=%d" todo-fst))
        (forward-line (- todo-fst 1)))
      
      (insert (concat todo-entry "\n"))
      (forward-line -1))
    (beginning-of-line nil)
    (message "")))

(defun todo-ask (lne) 
  "Ask whether entry is more important than at LNE."
  (if (not (equal todo-prv-lne lne))
      (progn
        (setq todo-prv-lne lne)
        (goto-char (point-min))
        (forward-line (- todo-prv-lne 1))
        (setq todo-prv-ans (y-or-n-p
			    (concat "More important than '"
				    (todo-line) "'? ")))))
  todo-prv-ans)

(defun todo-cmd-kill () "Delete current TODO list entry."
  (interactive)
  (if (> (count-lines (point-min) (point-max)) 0)
      (progn
	(let* ((todo-entry (todo-line))
	       (todo-answer (y-or-n-p (concat "Permanently remove '"
					      todo-entry "'? "))))
	  (if todo-answer
	      (progn
		(delete-region (point-at-bol) (+ 1 (point-at-eol))) 
		(forward-line -1)
		)
	    )
	  )
	(message "")
	)
    (message "No TODO list entry to delete.")
    )
  (beginning-of-line nil)
  )

(defun todo-cmd-rais () "Raise priority of current entry."
  (interactive)
  (if (> (count-lines (point-min) (point-max)) 0)
      (progn
	(setq todo-entry (todo-line))
	(delete-region (point-at-bol) (+ 1 (point-at-eol))) 
	(forward-line -1)
	(insert (concat todo-entry "\n"))
	(forward-line -1)
	(message "")
	)
    (message "No TODO list entry to raise.")
    )
  (beginning-of-line nil)
  )

(defun todo-cmd-lowr () "Lower priority of current entry."
  (interactive)
  (if (> (count-lines (point-min) (point-max)) 0)
      (progn
	(setq todo-entry (todo-line))
	(delete-region (point-at-bol) (+ 1 (point-at-eol))) 
	(forward-line 1)
	(insert (concat todo-entry "\n"))
	(forward-line -1)
	(message "")
	)
    (message "No TODO list entry to raise.")
    )
  (beginning-of-line nil)
  )

(defun todo-cmd-file () "File away the current TODO list entry."
  (interactive)
  (if (> (count-lines (point-min) (point-max)) 0)
      (progn
	(let ((time-stamp-format "%3b %2d, %y, %02I:%02M%p"))
	  (beginning-of-line nil)
	  (delete-region (point-at-bol) (search-forward todo-prefix))
	  (insert (time-stamp-string))
	  (end-of-line nil)
	  (insert (concat " (" (read-from-minibuffer "Comment: ") ")"))
	  (append-to-file (point-at-bol) (+ 1 (point-at-eol)) todo-file-done)
	  (delete-region (point-at-bol) (+ 1 (point-at-eol)))
	  (forward-line -1)
	  )
	(message "")
	)
    (message "No TODO list entry to delete.")
    )
  (beginning-of-line nil)
  )

;; ---------------------------------------------------------------------------

;; utility functions:  These are available in XEmacs, but not in Emacs 19.34

(if (not (fboundp 'point-at-bol))
    (defun point-at-bol ()
      (save-excursion
	(beginning-of-line)
	(point))))

(if (not (fboundp 'point-at-eol))
    (defun point-at-eol ()
      (save-excursion
	(end-of-line)
	(point))))

;; ---------------------------------------------------------------------------

(defvar todo-mode-popup-menu
  (purecopy '("Todo Mode Menu"
              ["Forward item"         todo-cmd-forw t]
              ["Backward item"        todo-cmd-back t]
              "---"
              ["Edit item"            todo-cmd-edit t]
              ["File item"            todo-cmd-file t]
              ["Insert new item"      todo-cmd-inst t]
              ["Kill item"            todo-cmd-kill t]
              "---"
              ["Lower item priority"  todo-cmd-lowr t]
              ["Raise item priority"  todo-cmd-rais t]
              "---"
              ["Next item"            todo-cmd-next t]
              ["Previous item"        todo-cmd-prev t]
              "---"
              ["Save"                 todo-cmd-save t]
              "---"
              ["Quit"                 todo-cmd-done t]
              )
	    )
  )

(defvar todo-cats nil "TODO categories.")
(defvar todo-category-number 0 "TODO category number.")

(defun todo-mode () "Major mode for editing TODO lists.\n\n\\{todo-mode-map}"
  (interactive)
  (setq major-mode 'todo-mode)
  (setq mode-name "TODO")
  (use-local-map todo-mode-map)
  (setq mode-popup-menu todo-mode-popup-menu)
  (run-hooks 'todo-mode-hook)
  )

(defun todo-show () "Show TODO list."
  (interactive)
  (find-file todo-file-do)
  (if (null todo-cats)
      (progn
	(todo-add-category "Todo")
	(goto-char (point-min))
	(goto-char (search-forward "--- End"))
	(let ((bol (point-at-bol)))
	  (forward-line 1)
	  (let* ((eol (+ (point-at-eol) 1))
		 (mrkr (buffer-substring bol eol)))
	    (delete-region bol eol)
	    (goto-char (point-max))
	    (insert mrkr)
	    )
	  )
	(save-buffer)
	(kill-buffer (current-buffer))
	(find-file todo-file-do)
	)
    )
  (beginning-of-line nil)
  (todo-cat-slct)
  )

(provide 'todomode)

;; ---------------------------------------------------------------------------

;; todomode.el ends here

;; ---------------------------------------------------------------------------