/* $OpenBSD$ */

/*
 * Copyright (c) 2007 Nicholas Marriott <nicholas.marriott@gmail.com>
 *
 * 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 <unistd.h>

#include "tmux.h"

/* Selected area in screen. */
struct screen_sel {
	int		 hidden;
	int		 rectangle;
	int		 modekeys;

	u_int		 sx;
	u_int		 sy;

	u_int		 ex;
	u_int		 ey;

	u_int		 clipx;

	struct grid_cell cell;
};

/* Entry on title stack. */
struct screen_title_entry {
	char				*text;

	TAILQ_ENTRY(screen_title_entry)	 entry;
};
TAILQ_HEAD(screen_titles, screen_title_entry);

static void	screen_resize_y(struct screen *, u_int, int, u_int *);
static void	screen_reflow(struct screen *, u_int, u_int *, u_int *, int);

/* Free titles stack. */
static void
screen_free_titles(struct screen *s)
{
	struct screen_title_entry	*title_entry;

	if (s->titles == NULL)
		return;

	while ((title_entry = TAILQ_FIRST(s->titles)) != NULL) {
		TAILQ_REMOVE(s->titles, title_entry, entry);
		free(title_entry->text);
		free(title_entry);
	}

	free(s->titles);
	s->titles = NULL;
}

/* 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->saved_grid = NULL;

	s->title = xstrdup("");
	s->titles = NULL;
	s->path = NULL;

	s->cstyle = SCREEN_CURSOR_DEFAULT;
	s->default_cstyle = SCREEN_CURSOR_DEFAULT;
	s->mode = MODE_CURSOR;
	s->default_mode = 0;
	s->ccolour = -1;
	s->default_ccolour = -1;
	s->tabs = NULL;
	s->sel = NULL;

#ifdef ENABLE_SIXEL
	TAILQ_INIT(&s->images);
	TAILQ_INIT(&s->saved_images);
#endif

	s->write_list = NULL;
	s->hyperlinks = 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|MODE_WRAP|(s->mode & MODE_CRLF);

	if (options_get_number(global_options, "extended-keys") == 2)
		s->mode = (s->mode & ~EXTENDED_KEY_MODES)|MODE_KEYS_EXTENDED;

	if (SCREEN_IS_ALTERNATE(s))
		screen_alternate_off(s, NULL, 0);
	s->saved_cx = UINT_MAX;
	s->saved_cy = UINT_MAX;

	screen_reset_tabs(s);

	grid_clear_lines(s->grid, s->grid->hsize, s->grid->sy, 8);

	screen_clear_selection(s);
	screen_free_titles(s);

#ifdef ENABLE_SIXEL
	image_free_all(s);
#endif

	screen_set_progress_bar(s, PROGRESS_BAR_HIDDEN, 0);
	screen_reset_hyperlinks(s);
}

/* Reset hyperlinks of a screen. */
void
screen_reset_hyperlinks(struct screen *s)
{
	if (s->hyperlinks == NULL)
		s->hyperlinks = hyperlinks_init();
	else
		hyperlinks_reset(s->hyperlinks);
}

/* Destroy a screen. */
void
screen_free(struct screen *s)
{
	free(s->sel);
	free(s->tabs);
	free(s->path);
	free(s->title);

	if (s->write_list != NULL)
		screen_write_free_list(s);

	if (SCREEN_IS_ALTERNATE(s))
		grid_destroy(s->saved_grid);
	grid_destroy(s->grid);

	if (s->hyperlinks != NULL)
		hyperlinks_free(s->hyperlinks);
	screen_free_titles(s);

#ifdef ENABLE_SIXEL
	image_free_all(s);
#endif
}

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

	free(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 default cursor style and colour from options. */
void
screen_set_default_cursor(struct screen *s, struct options *oo)
{
	struct grid_cell	gc;
	int			c;

	style_apply(&gc, oo, "cursor-colour", NULL);
	s->default_ccolour = gc.fg;

	c = options_get_number(oo, "cursor-style");
	s->default_mode = 0;
	screen_set_cursor_style(c, &s->default_cstyle, &s->default_mode);
}

/* Set screen cursor style and mode. */
void
screen_set_cursor_style(u_int style, enum screen_cursor_style *cstyle,
    int *mode)
{
	switch (style) {
	case 0:
		*cstyle = SCREEN_CURSOR_DEFAULT;
		break;
	case 1:
		*cstyle = SCREEN_CURSOR_BLOCK;
		*mode |= MODE_CURSOR_BLINKING;
		break;
	case 2:
		*cstyle = SCREEN_CURSOR_BLOCK;
		*mode &= ~MODE_CURSOR_BLINKING;
		break;
	case 3:
		*cstyle = SCREEN_CURSOR_UNDERLINE;
		*mode |= MODE_CURSOR_BLINKING;
		break;
	case 4:
		*cstyle = SCREEN_CURSOR_UNDERLINE;
		*mode &= ~MODE_CURSOR_BLINKING;
		break;
	case 5:
		*cstyle = SCREEN_CURSOR_BAR;
		*mode |= MODE_CURSOR_BLINKING;
		break;
	case 6:
		*cstyle = SCREEN_CURSOR_BAR;
		*mode &= ~MODE_CURSOR_BLINKING;
		break;
	}
}

/* Set screen cursor colour. */
void
screen_set_cursor_colour(struct screen *s, int colour)
{
	s->ccolour = colour;
}

/* Set screen title. */
int
screen_set_title(struct screen *s, const char *title, int untrusted)
{
	char	*new_title;

	new_title = clean_name(title, untrusted);
	if (new_title == NULL)
		return (0);
	free(s->title);
	s->title = new_title;
	return (1);
}

/* Set screen path. */
int
screen_set_path(struct screen *s, const char *path, int untrusted)
{
	char	*new_path;

	new_path = clean_name(path, untrusted);
	if (new_path == NULL)
		return (0);
	free(s->path);
	s->path = new_path;
	return (1);
}

/* Push the current title onto the stack. */
void
screen_push_title(struct screen *s)
{
	struct screen_title_entry *title_entry;

	log_debug("%s: %u", __func__, s->ntitles);

	while (s->ntitles >= 10) {
		title_entry = TAILQ_LAST(s->titles, screen_titles);
		free(title_entry->text);
		TAILQ_REMOVE(s->titles, title_entry, entry);
		free(title_entry);
		s->ntitles--;
	}

	if (s->titles == NULL) {
		s->titles = xmalloc(sizeof *s->titles);
		TAILQ_INIT(s->titles);
	}
	title_entry = xmalloc(sizeof *title_entry);
	title_entry->text = xstrdup(s->title);
	TAILQ_INSERT_HEAD(s->titles, title_entry, entry);
	s->ntitles++;
}

/*
 * Pop a title from the stack and set it as the screen title. If the stack is
 * empty, do nothing.
 */
void
screen_pop_title(struct screen *s)
{
	struct screen_title_entry *title_entry;

	if (s->titles == NULL)
		return;
	log_debug("%s: %u", __func__, s->ntitles);

	title_entry = TAILQ_FIRST(s->titles);
	if (title_entry != NULL) {
		free(s->title);
		s->title = title_entry->text;
		TAILQ_REMOVE(s->titles, title_entry, entry);
		free(title_entry);
		s->ntitles--;
	}
}

/*
 * Set the progress bar state and progress. The progress will not be updated
 * if p is negative.
 */
void
screen_set_progress_bar(struct screen *s, enum progress_bar_state pbs, int p)
{
	s->progress_bar.state = pbs;
	if (p >= 0 && pbs != PROGRESS_BAR_INDETERMINATE)
		s->progress_bar.progress = p;
}


/* Resize screen with options. */
void
screen_resize_cursor(struct screen *s, u_int sx, u_int sy, int reflow,
    int eat_empty, int cursor)
{
	u_int	cx = s->cx, cy = s->grid->hsize + s->cy;

	if (s->write_list != NULL)
		screen_write_free_list(s);

	log_debug("%s: new size %ux%u, now %ux%u (cursor %u,%u = %u,%u)",
	    __func__, sx, sy, screen_size_x(s), screen_size_y(s), s->cx, s->cy,
	    cx, cy);

	if (sx < 1)
		sx = 1;
	if (sy < 1)
		sy = 1;

	if (sx != screen_size_x(s)) {
		s->grid->sx = sx;
		screen_reset_tabs(s);
	} else
		reflow = 0;

	if (sy != screen_size_y(s))
		screen_resize_y(s, sy, eat_empty, &cy);

#ifdef ENABLE_SIXEL
	image_free_all(s);
#endif

	if (reflow)
		screen_reflow(s, sx, &cx, &cy, cursor);

	if (cy >= s->grid->hsize) {
		s->cx = cx;
		s->cy = cy - s->grid->hsize;
	} else {
		s->cx = 0;
		s->cy = 0;
	}

	log_debug("%s: cursor finished at %u,%u = %u,%u", __func__, s->cx,
	    s->cy, cx, cy);

	if (s->write_list != NULL)
		screen_write_make_list(s);
}

/* Resize screen. */
void
screen_resize(struct screen *s, u_int sx, u_int sy, int reflow)
{
	screen_resize_cursor(s, sx, sy, reflow, 1, 1);
}

static void
screen_resize_y(struct screen *s, u_int sy, int eat_empty, u_int *cy)
{
	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 scrolled
	 * history (not explicitly cleared from view) 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. */
		if (eat_empty) {
			available = oldy - 1 - s->cy;
			if (available > 0) {
				if (available > needed)
					available = needed;
				grid_view_delete_lines(gd, oldy - available,
				    available, 8);
			}
			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.
		 */
		available = s->cy;
		if (gd->flags & GRID_HISTORY) {
			gd->hscrolled += needed;
			gd->hsize += needed;
		} else if (needed > 0 && available > 0) {
			if (available > needed)
				available = needed;
			grid_view_delete_lines(gd, 0, available, 8);
			(*cy) -= available;
		}
	}

	/* Resize line array. */
	grid_adjust_lines(gd, gd->hsize + sy);

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

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

		/* Then fill the rest in with blanks. */
		for (i = gd->hsize + sy - needed; i < gd->hsize + sy; i++)
			grid_empty_line(gd, i, 8);
	}

	/* 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, u_int rectangle, u_int clipx, int modekeys,
    struct grid_cell *gc)
{
	if (s->sel == NULL)
		s->sel = xcalloc(1, sizeof *s->sel);

	memcpy(&s->sel->cell, gc, sizeof s->sel->cell);
	s->sel->hidden = 0;
	s->sel->rectangle = rectangle;
	s->sel->modekeys = modekeys;

	s->sel->sx = sx;
	s->sel->sy = sy;
	s->sel->ex = ex;
	s->sel->ey = ey;
	s->sel->clipx = clipx;
}

/* Clear selection. */
void
screen_clear_selection(struct screen *s)
{
	free(s->sel);
	s->sel = NULL;
}

/* Hide selection. */
void
screen_hide_selection(struct screen *s)
{
	if (s->sel != NULL)
		s->sel->hidden = 1;
}

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

	if (sel == NULL || sel->hidden)
		return (0);
	if (px < sel->clipx)
		return (0);

	if (sel->rectangle) {
		if (sel->sy < sel->ey) {
			/* start line < end line -- downward selection. */
			if (py < sel->sy || py > sel->ey)
				return (0);
		} else if (sel->sy > sel->ey) {
			/* start line > end line -- upward selection. */
			if (py > sel->sy || py < sel->ey)
				return (0);
		} else {
			/* starting line == ending line. */
			if (py != sel->sy)
				return (0);
		}

		/*
		 * Need to include the selection start row, but not the cursor
		 * row, which means the selection changes depending on which
		 * one is on the left.
		 */
		if (sel->ex < sel->sx) {
			/* Cursor (ex) is on the left. */
			if (px < sel->ex)
				return (0);

			if (px > sel->sx)
				return (0);
		} else {
			/* Selection start (sx) is on the left. */
			if (px < sel->sx)
				return (0);

			if (px > sel->ex)
				return (0);
		}
	} else {
		/*
		 * Like emacs, keep the top-left-most character, and drop the
		 * bottom-right-most, regardless of copy direction.
		 */
		if (sel->sy < sel->ey) {
			/* starting line < ending line -- downward selection. */
			if (py < sel->sy || py > sel->ey)
				return (0);

			if (py == sel->sy && px < sel->sx)
				return (0);

			if (sel->modekeys == MODEKEY_EMACS)
				xx = (sel->ex == 0 ? 0 : sel->ex - 1);
			else
				xx = sel->ex;
			if (py == sel->ey && px > xx)
				return (0);
		} else if (sel->sy > sel->ey) {
			/* starting line > ending line -- upward selection. */
			if (py > sel->sy || py < sel->ey)
				return (0);

			if (py == sel->ey && px < sel->ex)
				return (0);

			if (sel->modekeys == MODEKEY_EMACS)
				xx = sel->sx - 1;
			else
				xx = sel->sx;
			if (py == sel->sy && (sel->sx == 0 || px > xx))
				return (0);
		} else {
			/* starting line == ending line. */
			if (py != sel->sy)
				return (0);

			if (sel->ex < sel->sx) {
				/* cursor (ex) is on the left */
				if (sel->modekeys == MODEKEY_EMACS)
					xx = sel->sx - 1;
				else
					xx = sel->sx;
				if (px > xx || px < sel->ex)
					return (0);
			} else {
				/* selection start (sx) is on the left */
				if (sel->modekeys == MODEKEY_EMACS)
					xx = (sel->ex == 0 ? 0 : sel->ex - 1);
				else
					xx = sel->ex;
				if (px < sel->sx || px > xx)
					return (0);
			}
		}
	}

	return (1);
}

/* Get selected grid cell. */
int
screen_select_cell(struct screen *s, struct grid_cell *dst,
    const struct grid_cell *src)
{
	if (s->sel == NULL || s->sel->hidden)
		return (0);

	memcpy(dst, &s->sel->cell, sizeof *dst);
	if (COLOUR_DEFAULT(dst->fg))
		dst->fg = src->fg;
	if (COLOUR_DEFAULT(dst->bg))
		dst->bg = src->bg;
	utf8_copy(&dst->data, &src->data);
	dst->flags = src->flags;

	if (dst->attr & GRID_ATTR_NOATTR)
		dst->attr |= (src->attr & GRID_ATTR_CHARSET);
	else
		dst->attr |= src->attr;
	return (1);
}

/* Reflow wrapped lines. */
static void
screen_reflow(struct screen *s, u_int new_x, u_int *cx, u_int *cy, int cursor)
{
	u_int	wx, wy;

	if (cursor) {
		grid_wrap_position(s->grid, *cx, *cy, &wx, &wy);
		log_debug("%s: cursor %u,%u is %u,%u", __func__, *cx, *cy, wx,
		    wy);
	}

	grid_reflow(s->grid, new_x);

	if (cursor) {
		grid_unwrap_position(s->grid, cx, cy, wx, wy);
		log_debug("%s: new cursor is %u,%u", __func__, *cx, *cy);
	}
	else {
		*cx = 0;
		*cy = s->grid->hsize;
	}
}

/*
 * Enter alternative screen mode. A copy of the visible screen is saved and the
 * history is not updated.
 */
int
screen_alternate_on(struct screen *s, struct grid_cell *gc, int cursor)
{
	u_int		 sx, sy;
#ifdef ENABLE_SIXEL
	struct image	*im;
#endif

	if (SCREEN_IS_ALTERNATE(s))
		return 0;
	sx = screen_size_x(s);
	sy = screen_size_y(s);

	s->saved_grid = grid_create(sx, sy, 0);
	grid_duplicate_lines(s->saved_grid, 0, s->grid, screen_hsize(s), sy);
	if (cursor) {
		s->saved_cx = s->cx;
		s->saved_cy = s->cy;
	}
	memcpy(&s->saved_cell, gc, sizeof s->saved_cell);

#ifdef ENABLE_SIXEL
	TAILQ_CONCAT(&s->saved_images, &s->images, entry);
	TAILQ_FOREACH(im, &s->saved_images, entry)
	    im->list = &s->saved_images;
#endif

	grid_view_clear(s->grid, 0, 0, sx, sy, 8);

	s->saved_flags = s->grid->flags;
	s->grid->flags &= ~GRID_HISTORY;

	return 1;
}

/* Exit alternate screen mode and restore the copied grid. */
int
screen_alternate_off(struct screen *s, struct grid_cell *gc, int cursor)
{
	u_int		 sx = screen_size_x(s), sy = screen_size_y(s);
#ifdef ENABLE_SIXEL
	struct image	*im;
#endif

	/*
	 * If the current size is different, temporarily resize to the old size
	 * before copying back.
	 */
	if (SCREEN_IS_ALTERNATE(s))
		screen_resize(s, s->saved_grid->sx, s->saved_grid->sy, 0);

	/*
	 * Restore the cursor position and cell. This happens even if not
	 * currently in the alternate screen.
	 */
	if (cursor && s->saved_cx != UINT_MAX && s->saved_cy != UINT_MAX) {
		s->cx = s->saved_cx;
		s->cy = s->saved_cy;
		if (gc != NULL)
			memcpy(gc, &s->saved_cell, sizeof *gc);
	}

	/* If not in the alternate screen, do nothing more. */
	if (!SCREEN_IS_ALTERNATE(s)) {
		if (s->cx > screen_size_x(s) - 1)
			s->cx = screen_size_x(s) - 1;
		if (s->cy > screen_size_y(s) - 1)
			s->cy = screen_size_y(s) - 1;
		return 0;
	}

	/* Restore the saved grid. */
	grid_duplicate_lines(s->grid, screen_hsize(s), s->saved_grid, 0,
	    s->saved_grid->sy);

	/*
	 * Turn history back on (so resize can use it) and then resize back to
	 * the current size.
	 */
	if (s->saved_flags & GRID_HISTORY)
		s->grid->flags |= GRID_HISTORY;
	screen_resize(s, sx, sy, 1);

	grid_destroy(s->saved_grid);
	s->saved_grid = NULL;

#ifdef ENABLE_SIXEL
	image_free_all(s);
	TAILQ_CONCAT(&s->images, &s->saved_images, entry);
	TAILQ_FOREACH(im, &s->images, entry)
	    im->list = &s->images;
#endif

	if (s->cx > screen_size_x(s) - 1)
		s->cx = screen_size_x(s) - 1;
	if (s->cy > screen_size_y(s) - 1)
		s->cy = screen_size_y(s) - 1;

	return 1;
}

/* Get mode as a string. */
const char *
screen_mode_to_string(int mode)
{
	static char	tmp[1024];

	if (mode == 0)
		return ("NONE");
	if (mode == ALL_MODES)
		return ("ALL");

	*tmp = '\0';
	if (mode & MODE_CURSOR)
		strlcat(tmp, "CURSOR,", sizeof tmp);
	if (mode & MODE_INSERT)
		strlcat(tmp, "INSERT,", sizeof tmp);
	if (mode & MODE_KCURSOR)
		strlcat(tmp, "KCURSOR,", sizeof tmp);
	if (mode & MODE_KKEYPAD)
		strlcat(tmp, "KKEYPAD,", sizeof tmp);
	if (mode & MODE_WRAP)
		strlcat(tmp, "WRAP,", sizeof tmp);
	if (mode & MODE_MOUSE_STANDARD)
		strlcat(tmp, "MOUSE_STANDARD,", sizeof tmp);
	if (mode & MODE_MOUSE_BUTTON)
		strlcat(tmp, "MOUSE_BUTTON,", sizeof tmp);
	if (mode & MODE_CURSOR_BLINKING)
		strlcat(tmp, "CURSOR_BLINKING,", sizeof tmp);
	if (mode & MODE_CURSOR_VERY_VISIBLE)
		strlcat(tmp, "CURSOR_VERY_VISIBLE,", sizeof tmp);
	if (mode & MODE_CURSOR_BLINKING_SET)
		strlcat(tmp, "CURSOR_BLINKING_SET,", sizeof tmp);
	if (mode & MODE_MOUSE_UTF8)
		strlcat(tmp, "MOUSE_UTF8,", sizeof tmp);
	if (mode & MODE_MOUSE_SGR)
		strlcat(tmp, "MOUSE_SGR,", sizeof tmp);
	if (mode & MODE_BRACKETPASTE)
		strlcat(tmp, "BRACKETPASTE,", sizeof tmp);
	if (mode & MODE_FOCUSON)
		strlcat(tmp, "FOCUSON,", sizeof tmp);
	if (mode & MODE_MOUSE_ALL)
		strlcat(tmp, "MOUSE_ALL,", sizeof tmp);
	if (mode & MODE_ORIGIN)
		strlcat(tmp, "ORIGIN,", sizeof tmp);
	if (mode & MODE_CRLF)
		strlcat(tmp, "CRLF,", sizeof tmp);
	if (mode & MODE_KEYS_EXTENDED)
		strlcat(tmp, "KEYS_EXTENDED,", sizeof tmp);
	if (mode & MODE_KEYS_EXTENDED_2)
		strlcat(tmp, "KEYS_EXTENDED_2,", sizeof tmp);
	if (mode & MODE_THEME_UPDATES)
		strlcat(tmp, "THEME_UPDATES,", sizeof tmp);
	if (mode & MODE_SYNC)
		strlcat(tmp, "SYNC,", sizeof tmp);
	if (*tmp != '\0')
		tmp[strlen(tmp) - 1] = '\0';
	return (tmp);
}

/* Convert screen to a string. */
const char *
screen_print(struct screen *s, int line)
{
	static char		*buf;
	static size_t		 len = 16384;
	const char		*acs;
	u_int			 x, y;
	int			 n;
	size_t			 last = 0;
	struct utf8_data	 ud;
	struct grid_line	*gl;
	struct grid_cell_entry	*gce;

	if (buf == NULL)
		buf = xmalloc(len);

	for (y = 0; y < screen_hsize(s) + s->grid->sy; y++) {
		if (line >= 0 && y != (u_int)line)
			continue;
		n = snprintf(buf + last, len - last, "%.4d \"", y);
		if (n <= 0 || (u_int)n >= len - last)
			goto out;
		last += n;

		gl = &s->grid->linedata[y];
		for (x = 0; x < gl->cellused; x++) {
			gce = &gl->celldata[x];
			if (gce->flags & GRID_FLAG_PADDING)
				continue;

			if (~gce->flags & GRID_FLAG_EXTENDED) {
				if (last + 2 >= len)
					goto out;
				buf[last++] = gce->data.data;
			} else if (gce->flags & GRID_FLAG_TAB) {
				if (last + 2 >= len)
					goto out;
				buf[last++] = '\t';
			} else if (gce->flags & GRID_ATTR_CHARSET) {
				acs = tty_acs_get(NULL, gce->data.data);
				if (acs != NULL)
					n = strlen(acs);
				else {
					acs = &gce->data.data;
					n = 1;
				}
				if (last + n + 1 >= len)
					goto out;
				memcpy(buf + last, acs, n);
				last += n;
			} else {
				utf8_to_data(gl->extddata[gce->offset].data,
				    &ud);
				if (ud.size > 0) {
					if (last + ud.size + 1 >= len)
						goto out;
					memcpy(buf + last, ud.data, ud.size);
					last += ud.size;
				}
			}
		}

		if (last + 3 >= len)
			goto out;
		buf[last++] = '"';
		buf[last++] = '\n';
	}

out:
	buf[last] = '\0';
	return (buf);
}
