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When resizing a screen smaller in alternate screen mode, all the lines needed
could be consumed by deleting from the bottom, leaving none to be removed from
the top. In this case, don't call grid_view_delete_lines with ny of 0 as this
is incorrect and causes a bounds check to fatal error if built with -DDEBUG.

/* $OpenBSD: screen.c,v 1.9 2009/07/17 18:35:11 nicm Exp $ */

/*
 * Copyright (c) 2007 Nicholas Marriott <nicm@users.sourceforge.net>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF MIND, USE, DATA OR PROFITS, WHETHER
 * IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
 * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <sys/types.h>

#include <stdlib.h>
#include <string.h>
#include <vis.h>

#include "tmux.h"

void	screen_resize_x(struct screen *, u_int);
void	screen_resize_y(struct screen *, u_int);

/* Create a new screen. */
void
screen_init(struct screen *s, u_int sx, u_int sy, u_int hlimit)
{
	s->grid = grid_create(sx, sy, hlimit);

	s->title = xstrdup("");

	s->tabs = NULL;

	screen_reinit(s);
}

/* Reinitialise screen. */
void
screen_reinit(struct screen *s)
{
	s->cx = 0;
	s->cy = 0;

	s->rupper = 0;
	s->rlower = screen_size_y(s) - 1;

	s->mode = MODE_CURSOR;
	
	screen_reset_tabs(s);

	grid_clear_lines(s->grid, s->grid->hsize, s->grid->sy);

	screen_clear_selection(s);
}

/* Destroy a screen. */
void
screen_free(struct screen *s)
{
	xfree(s->title);
	grid_destroy(s->grid);
}

/* Reset tabs to default, eight spaces apart. */
void
screen_reset_tabs(struct screen *s)
{
	u_int	i;

	if (s->tabs != NULL)
		xfree(s->tabs);

	if ((s->tabs = bit_alloc(screen_size_x(s))) == NULL)
		fatal("bit_alloc failed");
	for (i = 8; i < screen_size_x(s); i += 8)
		bit_set(s->tabs, i);
}

/* Set screen title. */
void
screen_set_title(struct screen *s, const char *title)
{
	char	tmp[BUFSIZ];

	strnvis(tmp, title, sizeof tmp, VIS_OCTAL|VIS_TAB|VIS_NL);

	xfree(s->title);
	s->title = xstrdup(tmp);
}

/* Resize screen. */
void
screen_resize(struct screen *s, u_int sx, u_int sy)
{
	if (sx < 1)
		sx = 1;
	if (sy < 1)
		sy = 1;

	if (sx != screen_size_x(s)) {
		screen_resize_x(s, sx);

		/*
		 * It is unclear what should happen to tabs on resize. xterm
		 * seems to try and maintain them, rxvt resets them. Resetting
		 * is simpler and more reliable so let's do that.
		 */
		screen_reset_tabs(s);
	}

	if (sy != screen_size_y(s))
		screen_resize_y(s, sy);
}

void
screen_resize_x(struct screen *s, u_int sx)
{
	struct grid		*gd = s->grid;

	if (sx == 0)
		fatalx("zero size");

	/*
	 * Treat resizing horizontally simply: just ensure the cursor is
	 * on-screen and change the size. Don't bother to truncate any lines -
	 * then the data should be accessible if the size is then incrased.
	 *
	 * The only potential wrinkle is if UTF-8 double-width characters are
	 * left in the last column, but UTF-8 terminals should deal with this
	 * sanely.
	 */
	if (s->cx >= sx)
		s->cx = sx - 1;
	gd->sx = sx;
}

void
screen_resize_y(struct screen *s, u_int sy)
{
	struct grid	*gd = s->grid;
	u_int		 needed, available, oldy, i;

	if (sy == 0)
		fatalx("zero size");
	oldy = screen_size_y(s);

	/* 
	 * When resizing:
	 *
	 * If the height is decreasing, delete lines from the bottom until
	 * hitting the cursor, then push lines from the top into the history.
	 * 
	 * When increasing, pull as many lines as possible from the history to
	 * the top, then fill the remaining with blanks at the bottom.
	 */

	/* Size decreasing. */
	if (sy < oldy) {
		needed = oldy - sy;

		/* Delete as many lines as possible from the bottom. */
		available = oldy - 1 - s->cy;
		if (available > 0) {
			if (available > needed)
				available = needed;
			grid_view_delete_lines(gd, oldy - available, available);
		}
		needed -= available;

		/*
		 * Now just increase the history size, if possible, to take
		 * over the lines which are left. If history is off, delete
		 * lines from the top.
		 *
		 * XXX Should apply history limit?
		 */
		available = s->cy;
		if (gd->flags & GRID_HISTORY)
			gd->hsize += needed;
		else if (needed > 0 && available > 0) {
			if (available > needed)
				available = needed;
			grid_view_delete_lines(gd, 0, available);
		}
		s->cy -= needed;
 	}

	/* Resize line arrays. */
	gd->size = xrealloc(gd->size, gd->hsize + sy, sizeof *gd->size);
	gd->data = xrealloc(gd->data, gd->hsize + sy, sizeof *gd->data);
	gd->usize = xrealloc(gd->usize, gd->hsize + sy, sizeof *gd->usize);
	gd->udata = xrealloc(gd->udata, gd->hsize + sy, sizeof *gd->udata);

	/* Size increasing. */
	if (sy > oldy) {
		needed = sy - oldy;

		/*
		 * Try to pull as much as possible out of the history, if is
		 * is enabled.
		 */
		available = gd->hsize;
		if (gd->flags & GRID_HISTORY && available > 0) {
			if (available > needed)
				available = needed;
			gd->hsize -= available;
			s->cy += available;
		} else
			available = 0;
		needed -= available;

		/* Then fill the rest in with blanks. */
		for (i = gd->hsize + sy - needed; i < gd->hsize + sy; i++) {
			gd->size[i] = 0;
			gd->data[i] = NULL;
			gd->usize[i] = 0;
			gd->udata[i] = NULL;
		}
	}

	/* Set the new size, and reset the scroll region. */
	gd->sy = sy;
	s->rupper = 0;
	s->rlower = screen_size_y(s) - 1;
}

/* Set selection. */
void
screen_set_selection(struct screen *s,
    u_int sx, u_int sy, u_int ex, u_int ey, struct grid_cell *gc)
{
	struct screen_sel	*sel = &s->sel;

	memcpy(&sel->cell, gc, sizeof sel->cell);

	sel->flag = 1;
	if (ey < sy || (sy == ey && ex < sx)) {
		sel->sx = ex; sel->sy = ey;
		sel->ex = sx; sel->ey = sy;
	} else {
		sel->sx = sx; sel->sy = sy;
		sel->ex = ex; sel->ey = ey;
	}
}

/* Clear selection. */
void
screen_clear_selection(struct screen *s)
{
	struct screen_sel	*sel = &s->sel;

	sel->flag = 0;
}

/* Check if cell in selection. */
int
screen_check_selection(struct screen *s, u_int px, u_int py)
{
	struct screen_sel	*sel = &s->sel;

	if (!sel->flag || py < sel->sy || py > sel->ey)
		return (0);

	if (py == sel->sy && py == sel->ey) {
		if (px < sel->sx || px > sel->ex)
			return (0);
		return (1);
	}

	if ((py == sel->sy && px < sel->sx) || (py == sel->ey && px > sel->ex))
		return (0);
	return (1);
}