;;;; fill-mode.jl -- minor mode and functions for filling text
;;;  Copyright (C) 1994 John Harper <jsh@ukc.ac.uk>

;;; This file is part of Jade.

;;; Jade 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.

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

(provide 'fill-mode)

(defvar fill-column 71
  "Position at which the text filling commands break lines.")

(defvar fill-mode-p nil)
(make-variable-buffer-local 'fill-mode-p)

;;;###autoload
(defun fill-mode ()
  "Minor mode for automatically filling lines, i.e. word-wrapping. This makes
the SPC key checks if the cursor is past the fill-column. If so, the next
line is started."
  (interactive)
  (if fill-mode-p
      (progn
	(setq fill-mode-p nil)
	(remove-minor-mode 'fill-mode "Fill")
	(unbind-keys minor-mode-keymap "SPC"))
    (add-minor-mode 'fill-mode "Fill")
    (setq fill-mode-p t)
    (bind-keys minor-mode-keymap
      "SPC" 'fill-mode-spc)))

;;;###autoload
(defun fill-mode-on ()
  (interactive)
  (unless fill-mode-p
    (fill-mode))
  nil)

(defun fill-mode-spc ()
  (interactive)
  (when (> (pos-col (cursor-pos)) fill-column)
    (let
	((pos (cursor-pos)))
      (set-pos-col pos (1+ fill-column))
      (setq pos (unless (word-start pos) (forward-word -1 pos)))
      (insert "\n" pos)
      (let
	  ((end (left-char 1 (copy-pos pos))))
	(when (equal (get-char end) ?\ )
	  (delete-area end pos)))
      ;; Hack to auto-indent new line in indented-text-mode
      (when (eq major-mode 'indented-text-mode)
	(let
	    ((old-pos (make-mark)))
	  (goto-line-start)
	  (text-mode-indent-tab)
	  (goto-char (mark-pos old-pos))))))
  (insert " "))

;;;###autoload
(defun set-fill-column (&optional column)
  "Sets the column number for filling to (the variable `fill-column') to
COLUMN or the current column."
  (interactive)
  (setq fill-column (if (numberp column)
			column 
		      (pos-col (char-to-glyph-pos (cursor-pos)))))
  (format t "Fill column set to %d." (1+ fill-column)))