#| -*-Scheme-*-

Copyright (C) 1986, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994,
    1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
    2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016,
    2017, 2018, 2019, 2020, 2021, 2022 Massachusetts Institute of
    Technology

This file is part of MIT/GNU Scheme.

MIT/GNU Scheme 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 of the License, or (at
your option) any later version.

MIT/GNU Scheme 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 MIT/GNU Scheme; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301,
USA.

|#

;;;; Buffer Windows: Image Update

(declare (usual-integrations))

;;;; Insert/Delete

(define (%notice-window-changes! window)
  ;; Assumes that interrupts are disabled.
  (let ((group (%window-group window)))
    (if (fix:> (group-modified-tick group) (%window-modified-tick window))
	(let ((start (group-start-changes-index group))
	      (end (group-end-changes-index group)))
	  (if (%window-debug-trace window)
	      ((%window-debug-trace window) 'window window
					    '%notice-window-changes!))
	  (if (not (%window-force-redraw? window))
	      ;; If this change intersects the visible region of the
	      ;; buffer, request a display update.
	      (if start
		  (window-needs-redisplay! window)
		  ;; Otherwise mark the window to indicate that it has
		  ;; been updated to reflect these changes.
		  (%set-window-modified-tick! window
					      (group-modified-tick group))))
	  (if start
	      (begin
		;; If this change affects START-MARK, invalidate it
		;; and request a display update.
		(if (and (%window-start-line-mark window)
			 (%start-clobbered? window start end))
		    (begin
		      (clear-window-start! window)
		      (window-needs-redisplay! window)))
		;; If this change affects POINT, invalidate it and
		;; request a display update.
		(if (and (fix:<= start (%window-point-index window))
			 (fix:<= (%window-point-index window) end))
		    (begin
		      (%set-window-point-moved?! window 'SINCE-START-SET)
		      (window-needs-redisplay! window)))))))))

(define-integrable (%start-clobbered? window start end)
  (let ((wlstart (%window-start-line-index window))
	(wstart (%window-start-index window))
	(partial (%window-start-partial window)))
    (or (and (%window-current-start-delta window)
	     ;; If the delta between START-LINE and START has changed
	     ;; since the last redisplay, then the window start has
	     ;; been clobbered.  For example, if the first line was
	     ;; only partially visible, and is then entirely deleted,
	     ;; WLSTART and WSTART will be equal -- which would
	     ;; normally indicate that the window start is OK.
	     (not (and (fix:= (%window-current-start-delta window)
			      (fix:- wstart wlstart))
		       (fix:= (%window-current-start-partial window)
			      partial))))
	(and (if (and (fix:= wlstart wstart)
		      (fix:= 0 partial))
		 (fix:< start wstart)
		 (fix:<= start wstart))
	     (fix:<= wlstart end)))))

;;;; Clip

(define (make-clip-daemon window)
  ;; It is assumed that the clip daemon is called before the clipping
  ;; has been performed.  It is also assumed that interrupts are
  ;; disabled.
  (lambda (group start end)
    (if (not (%window-force-redraw? window))
	(begin
	  (if (%window-debug-trace window)
	      ((%window-debug-trace window) 'window window 'clip-daemon
					    group start end))
	  (if (not (%window-start-clip-mark window))
	      (begin
		(%set-window-start-clip-mark!
		 window
		 (make-permanent-mark group
				      (group-display-start-index group)
				      #t))
		(%set-window-end-clip-mark!
		 window
		 (make-permanent-mark group
				      (group-display-end-index group)
				      #f))))
	  (begin
	    (if (fix:> start (%window-start-clip-index window))
		(set-mark-index! (%window-start-clip-mark window) start))
	    (if (fix:< end (%window-end-clip-index window))
		(set-mark-index! (%window-end-clip-mark window) end)))
	  (if (and (not (window-needs-redisplay? window))
		   (or (fix:>= (%window-start-clip-index window)
			       (%window-current-start-index window))
		       (fix:<= (%window-end-clip-index window)
			       (%window-current-end-index window))))
	      (window-needs-redisplay! window))))
    (if (and (%window-start-line-mark window)
	     (or (fix:>= start (%window-start-line-index window))
		 (fix:< end (%window-start-index window))))
	(begin
	  (clear-window-start! window)
	  (window-needs-redisplay! window)))
    (let ((point (%window-point-index window)))
      (cond ((fix:< point start)
	     (set-window-point-index! window start)
	     (%set-window-point-moved?! window 'SINCE-START-SET))
	    ((fix:< end point)
	     (set-window-point-index! window end)
	     (%set-window-point-moved?! window 'SINCE-START-SET))))))

;;;; Update

(define (update-outlines! window)
  ;; This procedure sets FORCE-REDRAW? if any cached variable has changed.
  (%recache-window-buffer-local-variables! window)
  (%guarantee-start-mark! window)
  (if (%window-force-redraw? window)
      (begin
	(%set-window-force-redraw?! window #f)
	(preserve-nothing! window))
      (let ((start (%window-current-start-index window))
	    (end (%window-current-end-index window)))
	(cond ((or (not start)
		   (and (%window-start-clip-mark window)
			(or (fix:< start (%window-group-start-index window))
			    (fix:< (%window-group-start-index window)
				   (%window-start-clip-index window))
			    (fix:< (%window-group-end-index window) end)
			    (fix:< (%window-end-clip-index window)
				   (%window-group-end-index window)))))
	       (preserve-nothing! window))
	      ((and (fix:> (group-modified-tick (%window-group window))
			   (%window-modified-tick window))
		    (fix:<= start (%window-end-changes-index window))
		    (fix:<= (%window-start-changes-index window) end))
	       (let ((start-changes
		      (let ((start-changes
			     (%window-start-changes-index window)))
			(if (%window-group-start-index? window start-changes)
			    (%window-group-start-index window)
			    (%window-line-start-index window start-changes))))
		     (end-changes
		      (let ((end-changes (%window-end-changes-index window)))
			(if (%window-group-end-index? window end-changes)
			    (%window-group-end-index window)
			    (%window-line-end-index window end-changes)))))
		 (if (fix:<= start-changes start)
		     (if (fix:< end-changes end)
			 (preserve-bottom! window end-changes end)
			 (preserve-nothing! window))
		     (if (fix:< end-changes end)
			 (preserve-top-and-bottom! window
						   start start-changes
						   end-changes end)
			 (preserve-top! window start start-changes)))))
	      (else
	       (preserve-all! window start end)))))
  (%clear-window-outstanding-changes! window))

(define (preserve-top! window start start-changes)
  (let ((start-outline (%window-start-outline window))
	(start-y (%window-current-start-y window)))
    (let ((last-unchanged
	   (last-unchanged-outline start-outline
				   start
				   start-changes)))
      (deallocate-outlines! window
			    (outline-next last-unchanged)
			    (%window-end-outline window))
      (preserve-contiguous-region! window
				   (make-o3 window start-outline start start-y)
				   (make-o3 window
					    last-unchanged
					    (fix:- start-changes 1)
					    (outline-end-y start-outline
							   start-y))))))

(define (preserve-bottom! window end-changes end)
  (let ((end-outline (%window-end-outline window))
	(end-y (%window-current-end-y window)))
    (let ((first-unchanged
	   (first-unchanged-outline end-outline end end-changes)))
      (if (not (eq? first-unchanged (%window-start-outline window)))
	  (deallocate-outlines! window
				(%window-start-outline window)
				(outline-previous first-unchanged)))
      (preserve-contiguous-region! window
				   (make-o3 window
					    first-unchanged
					    (fix:+ end-changes 1)
					    (outline-start-y end-outline
							     end-y))
				   (make-o3 window end-outline end end-y)))))

(define (preserve-contiguous-region! window start end)
  (let ((wlstart (%window-start-line-index window))
	(wlsy (%window-start-line-y window)))
    (if (maybe-scroll window start end wlstart wlsy)
	(fill-edges window start end)
	(regenerate-outlines window wlstart wlsy))))

(define (preserve-top-and-bottom! window start start-changes end-changes end)
  (let ((wlstart (%window-start-line-index window))
	(wlsy (%window-start-line-y window))
	(top-head (%window-start-outline window))
	(bot-tail (%window-end-outline window))
	(top-start-y (%window-current-start-y window))
	(bot-end-y (%window-current-end-y window)))
    (let ((top-tail (last-unchanged-outline top-head start start-changes))
	  (bot-head (first-unchanged-outline bot-tail end end-changes)))
      (deallocate-outlines! window
			    (outline-next top-tail)
			    (outline-previous bot-head))
      (let ((top-start (make-o3 window top-head start top-start-y))
	    (top-end
	     (make-o3 window
		      top-tail
		      (fix:- start-changes 1)
		      (outline-end-y top-head top-start-y)))
	    (bot-start
	     (make-o3 window
		      bot-head
		      (fix:+ end-changes 1)
		      (outline-start-y bot-tail bot-end-y)))
	    (bot-end (make-o3 window bot-tail end bot-end-y)))
	(if (maybe-scroll window top-start top-end wlstart wlsy)
	    (if (maybe-scroll window bot-start bot-end wlstart wlsy)
		(begin
		  (fill-middle window top-end bot-start)
		  (deallocate-o3! window top-end)
		  (deallocate-o3! window bot-start)
		  (fill-edges window top-start bot-end))
		(fill-edges window top-start top-end))
	    (if (maybe-scroll window bot-start bot-end wlstart wlsy)
		(fill-edges window bot-start bot-end)
		(regenerate-outlines window wlstart wlsy)))))))

(define (preserve-all! window start-index end-index)
  (let ((wlstart (%window-start-line-index window))
	(wlsy (%window-start-line-y window))
	(start-y (%window-current-start-y window))
	(end-y (%window-current-end-y window)))
    (let ((scroll-down
	   (lambda (y)
	     (let ((start
		    (make-o3 window
			     (%window-start-outline window)
			     start-index
			     start-y))
		   (end
		    (make-o3 window
			     (%window-end-outline window)
			     end-index
			     end-y)))
	       (if (scroll-lines-down window start end y)
		   (begin
		     (fill-top window start)
		     (set-outlines! window start end))
		   (regenerate-outlines window wlstart wlsy)))))
	  (scroll-up
	   (lambda (y)
	     (let ((start
		    (make-o3 window
			     (%window-start-outline window)
			     start-index
			     start-y))
		   (end
		    (make-o3 window
			     (%window-end-outline window)
			     end-index
			     end-y)))
	       (if (scroll-lines-up window start end y)
		   (begin
		     (fill-bottom window end)
		     (set-outlines! window start end))
		   (regenerate-outlines window wlstart wlsy))))))
      (cond ((fix:= wlstart start-index)
	     (cond ((fix:= wlsy start-y)
		    (if (%window-point-moved? window)
			(update-cursor! window)
			(%window-modeline-event! window 'PRESERVE-ALL!)))
		   ((fix:< wlsy start-y)
		    (scroll-up wlsy))
		   (else
		    (scroll-down wlsy))))
	    ((fix:< wlstart start-index)
	     (let ((y
		    (predict-y-limited window wlstart wlsy start-index start-y
				       (window-y-size window))))
	       (if (not y)
		   (regenerate-outlines window wlstart wlsy)
		   (scroll-down y))))
	    (else
	     (let ((y
		    (predict-y-limited window wlstart wlsy start-index
				       (fix:- 1 (fix:- end-y start-y))
				       1)))
	       (if (not y)
		   (regenerate-outlines window wlstart wlsy)
		   (scroll-up y))))))))

(define-integrable (preserve-nothing! window)
  (regenerate-outlines window
		       (%window-start-line-index window)
		       (%window-start-line-y window)))

(define (first-unchanged-outline end-outline end end-changes)
  (let loop ((outline end-outline) (end end))
    (let ((end-next (fix:- end (fix:+ (outline-index-length outline) 1))))
      (if (fix:> end-next end-changes)
	  (begin
	    (if (not (outline-previous outline))
		(error "can't find END-CHANGES"))
	    (loop (outline-previous outline) end-next))
	  (begin
	    (if (not (fix:= end-next end-changes))
		(error "overshot END-CHANGES" end-next end-changes))
	    outline)))))

(define (last-unchanged-outline start-outline start start-changes)
  (let loop ((outline start-outline) (start start))
    (let ((start-next (fix:+ start (fix:+ (outline-index-length outline) 1))))
      (if (fix:< start-next start-changes)
	  (begin
	    (if (not (outline-next outline))
		(error "can't find START-CHANGES"))
	    (loop (outline-next outline) start-next))
	  (begin
	    (if (not (fix:= start-next start-changes))
		(error "overshot START-CHANGES" start-next start-changes))
	    outline)))))

(define (regenerate-outlines window wlstart wlsy)
  (let ((start (make-o3 window #f wlstart wlsy))
	(end (make-o3 window #f #f #f)))
    (generate-outlines window start end)
    (set-outlines! window start end)))

(define-integrable (fill-edges window start end)
  (fill-top window start)
  (fill-bottom window end)
  (set-outlines! window start end))

(define (maybe-scroll window start end wlstart wlsy)
  (let ((y
	 (predict-y-limited window wlstart wlsy
			    (o3-index start)
			    (fix:- 1 (fix:- (o3-y end) (o3-y start)))
			    (window-y-size window))))
    (cond ((not y)
	   (deallocate-outlines! window (o3-outline start) (o3-outline end))
	   (deallocate-o3! window start)
	   (deallocate-o3! window end)
	   #f)
	  ((fix:= (o3-y start) y)
	   #t)
	  ((fix:< (o3-y start) y)
	   (scroll-lines-down window start end y))
	  (else
	   (scroll-lines-up window start end y)))))

;;;; Direct Output

;;; The direct output procedures are hairy and should be used only
;;; under restricted conditions.  In particular, the cursor may not be
;;; at the right margin (for insert and forward) or the left margin
;;; (for backward), and the character being inserted must be an
;;; ordinary graphic character.  For insert, the buffer must be
;;; modifiable, and the modeline must already show that it has been
;;; modified.  None of the procedures may be used if the window needs
;;; redisplay.

(define (buffer-window/needs-redisplay? window)
  (%notice-window-changes! window)
  (or (window-needs-redisplay? window)
      (not (%window-saved-screen window))
      (screen-needs-update? (%window-saved-screen window))))

(define (buffer-window/direct-output-cursor! window)
  (if (%window-debug-trace window)
      ((%window-debug-trace window) 'window window 'direct-output-cursor!))
  (let ((mask (set-interrupt-enables! interrupt-mask/gc-ok)))
    (let ((x-start (inferior-x-start (%window-cursor-inferior window)))
	  (y-start (inferior-y-start (%window-cursor-inferior window))))
      (screen-direct-output-move-cursor
       (%window-saved-screen window)
       (fix:+ (%window-saved-x-start window) x-start)
       (fix:+ (%window-saved-y-start window) y-start)))
    (set-interrupt-enables! mask)
    unspecific))

(define (buffer-window/direct-output-forward-char! window)
  (if (%window-debug-trace window)
      ((%window-debug-trace window) 'window window
				    'direct-output-forward-char!))
  (let ((mask (set-interrupt-enables! interrupt-mask/gc-ok)))
    (set-window-point-index! window (fix:+ (%window-point-index window) 1))
    (let ((x-start
	   (fix:+ (inferior-x-start (%window-cursor-inferior window)) 1))
	  (y-start (inferior-y-start (%window-cursor-inferior window))))
      (screen-direct-output-move-cursor
       (%window-saved-screen window)
       (fix:+ (%window-saved-x-start window) x-start)
       (fix:+ (%window-saved-y-start window) y-start))
      (%set-inferior-x-start! (%window-cursor-inferior window) x-start))
    (set-interrupt-enables! mask)
    unspecific))

(define (buffer-window/direct-output-backward-char! window)
  (if (%window-debug-trace window)
      ((%window-debug-trace window) 'window window
				    'direct-output-backward-char!))
  (let ((mask (set-interrupt-enables! interrupt-mask/gc-ok)))
    (set-window-point-index! window (fix:- (%window-point-index window) 1))
    (let ((x-start
	   (fix:- (inferior-x-start (%window-cursor-inferior window)) 1))
	  (y-start (inferior-y-start (%window-cursor-inferior window))))
      (screen-direct-output-move-cursor
       (%window-saved-screen window)
       (fix:+ (%window-saved-x-start window) x-start)
       (fix:+ (%window-saved-y-start window) y-start))
      (%set-inferior-x-start! (%window-cursor-inferior window) x-start))
    (set-interrupt-enables! mask)
    unspecific))

(define (buffer-window/home-cursor! window)
  (if (%window-debug-trace window)
      ((%window-debug-trace window) 'window window 'home-cursor!))
  (if (and (%window-saved-screen window)
	   (fix:<= (%window-saved-xl window) 0)
	   (fix:< 0 (%window-saved-xu window))
	   (fix:<= (%window-saved-yl window) 0)
	   (fix:< 0 (%window-saved-yu window)))
      (let ((mask (set-interrupt-enables! interrupt-mask/gc-ok)))
	(screen-direct-output-move-cursor (%window-saved-screen window)
					  (%window-saved-x-start window)
					  (%window-saved-y-start window))
	(set-interrupt-enables! mask)
	unspecific)))

(define (buffer-window/direct-output-insert-char! window char)
  (if (%window-debug-trace window)
      ((%window-debug-trace window) 'window window
				    'direct-output-insert-char! char))
  (let ((mask (set-interrupt-enables! interrupt-mask/gc-ok)))
    (let ((x-start (inferior-x-start (%window-cursor-inferior window)))
	  (y-start (inferior-y-start (%window-cursor-inferior window))))
      (screen-direct-output-char
       (%window-saved-screen window)
       (fix:+ (%window-saved-x-start window) x-start)
       (fix:+ (%window-saved-y-start window) y-start)
       char
       #f)
      (let ((outline (direct-output-outline window y-start)))
	(set-outline-index-length! outline
				   (fix:+ (outline-index-length outline) 1)))
      (%set-inferior-x-start! (%window-cursor-inferior window)
			      (fix:+ x-start 1)))
    (update-modified-tick! window)
    (set-interrupt-enables! mask)
    unspecific))

(define (buffer-window/direct-output-insert-substring! window string start end)
  (if (%window-debug-trace window)
      ((%window-debug-trace window) 'window window
				    'direct-output-insert-substring!
				    (string-copy string) start end))
  (let ((mask (set-interrupt-enables! interrupt-mask/gc-ok)))
    (group-insert-substring! (%window-group window)
			     (%window-point-index window)
			     string start end)
    (let ((x-start (inferior-x-start (%window-cursor-inferior window)))
	  (y-start (inferior-y-start (%window-cursor-inferior window)))
	  (length (fix:- end start)))
      (screen-direct-output-substring
       (%window-saved-screen window)
       (fix:+ (%window-saved-x-start window) x-start)
       (fix:+ (%window-saved-y-start window) y-start)
       string start end
       #f)
      (let ((outline (direct-output-outline window y-start)))
	(set-outline-index-length! outline
				   (fix:+ (outline-index-length outline)
					  length)))
      (%set-inferior-x-start! (%window-cursor-inferior window)
			      (fix:+ x-start length)))
    (update-modified-tick! window)
    (set-interrupt-enables! mask)
    unspecific))

(define (direct-output-outline window y)
  (let loop
      ((outline (%window-start-outline window))
       (start-y (%window-current-start-y window)))
    (let ((end-y (fix:+ start-y (outline-y-size outline))))
      (if (fix:< y end-y)
	  outline
	  (loop (outline-next outline) end-y)))))

(define (buffer-window/direct-output-insert-newline! window)
  (if (%window-debug-trace window)
      ((%window-debug-trace window) 'window window
				    'direct-output-insert-newline!))
  (let ((mask (set-interrupt-enables! interrupt-mask/gc-ok)))
    (group-insert-char! (%window-group window)
			(%window-point-index window)
			#\newline)
    (let ((end-y (%window-current-end-y window)))
      (screen-direct-output-move-cursor (%window-saved-screen window)
					(%window-saved-x-start window)
					(fix:+ (%window-saved-y-start window)
					       end-y))
      (%set-window-end-outline!
       window
       (make-outline window 0 1 (%window-end-outline window) #f))
      (%set-window-current-end-y! window (fix:+ end-y 1))
      (update-blank-inferior! window #f)
      (%set-inferior-x-start! (%window-cursor-inferior window) 0)
      (%set-inferior-y-start! (%window-cursor-inferior window) end-y))
    (update-modified-tick! window)
    (set-interrupt-enables! mask)
    unspecific))