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Add support for OSC 8 hyperlinks (a VTE extension now supported by other
terminals such as iTerm2). Originally written by me then extended and
completed by first Will Noble and later Jeff Chiang. GitHub issues 911,
2621, 2890, 3240.

/* $OpenBSD: grid.c,v 1.125 2022/06/30 09:55:53 nicm Exp $ */

/*
 * Copyright (c) 2008 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 "tmux.h"

/*
 * Grid data. This is the basic data structure that represents what is shown on
 * screen.
 *
 * A grid is a grid of cells (struct grid_cell). Lines are not allocated until
 * cells in that line are written to. The grid is split into history and
 * viewable data with the history starting at row (line) 0 and extending to
 * (hsize - 1); from hsize to hsize + (sy - 1) is the viewable data. All
 * functions in this file work on absolute coordinates, grid-view.c has
 * functions which work on the screen data.
 */

/* Default grid cell data. */
const struct grid_cell grid_default_cell = {
	{ { ' ' }, 0, 1, 1 }, 0, 0, 8, 8, 0, 0
};

/*
 * Padding grid cell data. Padding cells are the only zero width cell that
 * appears in the grid - because of this, they are always extended cells.
 */
static const struct grid_cell grid_padding_cell = {
	{ { '!' }, 0, 0, 0 }, 0, GRID_FLAG_PADDING, 8, 8, 0, 0
};

/* Cleared grid cell data. */
static const struct grid_cell grid_cleared_cell = {
	{ { ' ' }, 0, 1, 1 }, 0, GRID_FLAG_CLEARED, 8, 8, 0, 0
};
static const struct grid_cell_entry grid_cleared_entry = {
	GRID_FLAG_CLEARED, { .data = { 0, 8, 8, ' ' } }
};

/* Store cell in entry. */
static void
grid_store_cell(struct grid_cell_entry *gce, const struct grid_cell *gc,
    u_char c)
{
	gce->flags = (gc->flags & ~GRID_FLAG_CLEARED);

	gce->data.fg = gc->fg & 0xff;
	if (gc->fg & COLOUR_FLAG_256)
		gce->flags |= GRID_FLAG_FG256;

	gce->data.bg = gc->bg & 0xff;
	if (gc->bg & COLOUR_FLAG_256)
		gce->flags |= GRID_FLAG_BG256;

	gce->data.attr = gc->attr;
	gce->data.data = c;
}

/* Check if a cell should be an extended cell. */
static int
grid_need_extended_cell(const struct grid_cell_entry *gce,
    const struct grid_cell *gc)
{
	if (gce->flags & GRID_FLAG_EXTENDED)
		return (1);
	if (gc->attr > 0xff)
		return (1);
	if (gc->data.size != 1 || gc->data.width != 1)
		return (1);
	if ((gc->fg & COLOUR_FLAG_RGB) || (gc->bg & COLOUR_FLAG_RGB))
		return (1);
	if (gc->us != 0) /* only supports 256 or RGB */
		return (1);
	if (gc->link != 0)
		return (1);
	return (0);
}

/* Get an extended cell. */
static void
grid_get_extended_cell(struct grid_line *gl, struct grid_cell_entry *gce,
    int flags)
{
	u_int at = gl->extdsize + 1;

	gl->extddata = xreallocarray(gl->extddata, at, sizeof *gl->extddata);
	gl->extdsize = at;

	gce->offset = at - 1;
	gce->flags = (flags | GRID_FLAG_EXTENDED);
}

/* Set cell as extended. */
static struct grid_extd_entry *
grid_extended_cell(struct grid_line *gl, struct grid_cell_entry *gce,
    const struct grid_cell *gc)
{
	struct grid_extd_entry	*gee;
	int			 flags = (gc->flags & ~GRID_FLAG_CLEARED);
	utf8_char		 uc;

	if (~gce->flags & GRID_FLAG_EXTENDED)
		grid_get_extended_cell(gl, gce, flags);
	else if (gce->offset >= gl->extdsize)
		fatalx("offset too big");
	gl->flags |= GRID_LINE_EXTENDED;

	utf8_from_data(&gc->data, &uc);

	gee = &gl->extddata[gce->offset];
	gee->data = uc;
	gee->attr = gc->attr;
	gee->flags = flags;
	gee->fg = gc->fg;
	gee->bg = gc->bg;
	gee->us = gc->us;
	gee->link = gc->link;
	return (gee);
}

/* Free up unused extended cells. */
static void
grid_compact_line(struct grid_line *gl)
{
	int			 new_extdsize = 0;
	struct grid_extd_entry	*new_extddata;
	struct grid_cell_entry	*gce;
	struct grid_extd_entry	*gee;
	u_int			 px, idx;

	if (gl->extdsize == 0)
		return;

	for (px = 0; px < gl->cellsize; px++) {
		gce = &gl->celldata[px];
		if (gce->flags & GRID_FLAG_EXTENDED)
			new_extdsize++;
	}

	if (new_extdsize == 0) {
		free(gl->extddata);
		gl->extddata = NULL;
		gl->extdsize = 0;
		return;
	}
	new_extddata = xreallocarray(NULL, new_extdsize, sizeof *gl->extddata);

	idx = 0;
	for (px = 0; px < gl->cellsize; px++) {
		gce = &gl->celldata[px];
		if (gce->flags & GRID_FLAG_EXTENDED) {
			gee = &gl->extddata[gce->offset];
			memcpy(&new_extddata[idx], gee, sizeof *gee);
			gce->offset = idx++;
		}
	}

	free(gl->extddata);
	gl->extddata = new_extddata;
	gl->extdsize = new_extdsize;
}

/* Get line data. */
struct grid_line *
grid_get_line(struct grid *gd, u_int line)
{
	return (&gd->linedata[line]);
}

/* Adjust number of lines. */
void
grid_adjust_lines(struct grid *gd, u_int lines)
{
	gd->linedata = xreallocarray(gd->linedata, lines, sizeof *gd->linedata);
}

/* Copy default into a cell. */
static void
grid_clear_cell(struct grid *gd, u_int px, u_int py, u_int bg)
{
	struct grid_line	*gl = &gd->linedata[py];
	struct grid_cell_entry	*gce = &gl->celldata[px];
	struct grid_extd_entry	*gee;

	memcpy(gce, &grid_cleared_entry, sizeof *gce);
	if (bg != 8) {
		if (bg & COLOUR_FLAG_RGB) {
			grid_get_extended_cell(gl, gce, gce->flags);
			gee = grid_extended_cell(gl, gce, &grid_cleared_cell);
			gee->bg = bg;
		} else {
			if (bg & COLOUR_FLAG_256)
				gce->flags |= GRID_FLAG_BG256;
			gce->data.bg = bg;
		}
	}
}

/* Check grid y position. */
static int
grid_check_y(struct grid *gd, const char *from, u_int py)
{
	if (py >= gd->hsize + gd->sy) {
		log_debug("%s: y out of range: %u", from, py);
		return (-1);
	}
	return (0);
}

/* Check if two styles are (visibly) the same. */
int
grid_cells_look_equal(const struct grid_cell *gc1, const struct grid_cell *gc2)
{
	if (gc1->fg != gc2->fg || gc1->bg != gc2->bg)
		return (0);
	if (gc1->attr != gc2->attr || gc1->flags != gc2->flags)
		return (0);
	if (gc1->link != gc2->link)
		return (0);
	return (1);
}

/* Compare grid cells. Return 1 if equal, 0 if not. */
int
grid_cells_equal(const struct grid_cell *gc1, const struct grid_cell *gc2)
{
	if (!grid_cells_look_equal(gc1, gc2))
		return (0);
	if (gc1->data.width != gc2->data.width)
		return (0);
	if (gc1->data.size != gc2->data.size)
		return (0);
	return (memcmp(gc1->data.data, gc2->data.data, gc1->data.size) == 0);
}

/* Free one line. */
static void
grid_free_line(struct grid *gd, u_int py)
{
	free(gd->linedata[py].celldata);
	gd->linedata[py].celldata = NULL;
	free(gd->linedata[py].extddata);
	gd->linedata[py].extddata = NULL;
}

/* Free several lines. */
static void
grid_free_lines(struct grid *gd, u_int py, u_int ny)
{
	u_int	yy;

	for (yy = py; yy < py + ny; yy++)
		grid_free_line(gd, yy);
}

/* Create a new grid. */
struct grid *
grid_create(u_int sx, u_int sy, u_int hlimit)
{
	struct grid	*gd;

	gd = xmalloc(sizeof *gd);
	gd->sx = sx;
	gd->sy = sy;

	if (hlimit != 0)
		gd->flags = GRID_HISTORY;
	else
		gd->flags = 0;

	gd->hscrolled = 0;
	gd->hsize = 0;
	gd->hlimit = hlimit;

	if (gd->sy != 0)
		gd->linedata = xcalloc(gd->sy, sizeof *gd->linedata);
	else
		gd->linedata = NULL;

	return (gd);
}

/* Destroy grid. */
void
grid_destroy(struct grid *gd)
{
	grid_free_lines(gd, 0, gd->hsize + gd->sy);

	free(gd->linedata);

	free(gd);
}

/* Compare grids. */
int
grid_compare(struct grid *ga, struct grid *gb)
{
	struct grid_line	*gla, *glb;
	struct grid_cell	 gca, gcb;
	u_int			 xx, yy;

	if (ga->sx != gb->sx || ga->sy != gb->sy)
		return (1);

	for (yy = 0; yy < ga->sy; yy++) {
		gla = &ga->linedata[yy];
		glb = &gb->linedata[yy];
		if (gla->cellsize != glb->cellsize)
			return (1);
		for (xx = 0; xx < gla->cellsize; xx++) {
			grid_get_cell(ga, xx, yy, &gca);
			grid_get_cell(gb, xx, yy, &gcb);
			if (!grid_cells_equal(&gca, &gcb))
				return (1);
		}
	}

	return (0);
}

/* Trim lines from the history. */
static void
grid_trim_history(struct grid *gd, u_int ny)
{
	grid_free_lines(gd, 0, ny);
	memmove(&gd->linedata[0], &gd->linedata[ny],
	    (gd->hsize + gd->sy - ny) * (sizeof *gd->linedata));
}

/*
 * Collect lines from the history if at the limit. Free the top (oldest) 10%
 * and shift up.
 */
void
grid_collect_history(struct grid *gd)
{
	u_int	ny;

	if (gd->hsize == 0 || gd->hsize < gd->hlimit)
		return;

	ny = gd->hlimit / 10;
	if (ny < 1)
		ny = 1;
	if (ny > gd->hsize)
		ny = gd->hsize;

	/*
	 * Free the lines from 0 to ny then move the remaining lines over
	 * them.
	 */
	grid_trim_history(gd, ny);

	gd->hsize -= ny;
	if (gd->hscrolled > gd->hsize)
		gd->hscrolled = gd->hsize;
}

/* Remove lines from the bottom of the history. */
void
grid_remove_history(struct grid *gd, u_int ny)
{
	u_int	yy;

	if (ny > gd->hsize)
		return;
	for (yy = 0; yy < ny; yy++)
		grid_free_line(gd, gd->hsize + gd->sy - 1 - yy);
	gd->hsize -= ny;
}

/*
 * Scroll the entire visible screen, moving one line into the history. Just
 * allocate a new line at the bottom and move the history size indicator.
 */
void
grid_scroll_history(struct grid *gd, u_int bg)
{
	u_int	yy;

	yy = gd->hsize + gd->sy;
	gd->linedata = xreallocarray(gd->linedata, yy + 1,
	    sizeof *gd->linedata);
	grid_empty_line(gd, yy, bg);

	gd->hscrolled++;
	grid_compact_line(&gd->linedata[gd->hsize]);
	gd->linedata[gd->hsize].time = current_time;
	gd->hsize++;
}

/* Clear the history. */
void
grid_clear_history(struct grid *gd)
{
	grid_trim_history(gd, gd->hsize);

	gd->hscrolled = 0;
	gd->hsize = 0;

	gd->linedata = xreallocarray(gd->linedata, gd->sy,
	    sizeof *gd->linedata);
}

/* Scroll a region up, moving the top line into the history. */
void
grid_scroll_history_region(struct grid *gd, u_int upper, u_int lower, u_int bg)
{
	struct grid_line	*gl_history, *gl_upper;
	u_int			 yy;

	/* Create a space for a new line. */
	yy = gd->hsize + gd->sy;
	gd->linedata = xreallocarray(gd->linedata, yy + 1,
	    sizeof *gd->linedata);

	/* Move the entire screen down to free a space for this line. */
	gl_history = &gd->linedata[gd->hsize];
	memmove(gl_history + 1, gl_history, gd->sy * sizeof *gl_history);

	/* Adjust the region and find its start and end. */
	upper++;
	gl_upper = &gd->linedata[upper];
	lower++;

	/* Move the line into the history. */
	memcpy(gl_history, gl_upper, sizeof *gl_history);
	gl_history->time = current_time;

	/* Then move the region up and clear the bottom line. */
	memmove(gl_upper, gl_upper + 1, (lower - upper) * sizeof *gl_upper);
	grid_empty_line(gd, lower, bg);

	/* Move the history offset down over the line. */
	gd->hscrolled++;
	gd->hsize++;
}

/* Expand line to fit to cell. */
static void
grid_expand_line(struct grid *gd, u_int py, u_int sx, u_int bg)
{
	struct grid_line	*gl;
	u_int			 xx;

	gl = &gd->linedata[py];
	if (sx <= gl->cellsize)
		return;

	if (sx < gd->sx / 4)
		sx = gd->sx / 4;
	else if (sx < gd->sx / 2)
		sx = gd->sx / 2;
	else if (gd->sx > sx)
		sx = gd->sx;

	gl->celldata = xreallocarray(gl->celldata, sx, sizeof *gl->celldata);
	for (xx = gl->cellsize; xx < sx; xx++)
		grid_clear_cell(gd, xx, py, bg);
	gl->cellsize = sx;
}

/* Empty a line and set background colour if needed. */
void
grid_empty_line(struct grid *gd, u_int py, u_int bg)
{
	memset(&gd->linedata[py], 0, sizeof gd->linedata[py]);
	if (!COLOUR_DEFAULT(bg))
		grid_expand_line(gd, py, gd->sx, bg);
}

/* Peek at grid line. */
const struct grid_line *
grid_peek_line(struct grid *gd, u_int py)
{
	if (grid_check_y(gd, __func__, py) != 0)
		return (NULL);
	return (&gd->linedata[py]);
}

/* Get cell from line. */
static void
grid_get_cell1(struct grid_line *gl, u_int px, struct grid_cell *gc)
{
	struct grid_cell_entry	*gce = &gl->celldata[px];
	struct grid_extd_entry	*gee;

	if (gce->flags & GRID_FLAG_EXTENDED) {
		if (gce->offset >= gl->extdsize)
			memcpy(gc, &grid_default_cell, sizeof *gc);
		else {
			gee = &gl->extddata[gce->offset];
			gc->flags = gee->flags;
			gc->attr = gee->attr;
			gc->fg = gee->fg;
			gc->bg = gee->bg;
			gc->us = gee->us;
			gc->link = gee->link;
			utf8_to_data(gee->data, &gc->data);
		}
		return;
	}

	gc->flags = gce->flags & ~(GRID_FLAG_FG256|GRID_FLAG_BG256);
	gc->attr = gce->data.attr;
	gc->fg = gce->data.fg;
	if (gce->flags & GRID_FLAG_FG256)
		gc->fg |= COLOUR_FLAG_256;
	gc->bg = gce->data.bg;
	if (gce->flags & GRID_FLAG_BG256)
		gc->bg |= COLOUR_FLAG_256;
	gc->us = 0;
	utf8_set(&gc->data, gce->data.data);
	gc->link = 0;
}

/* Get cell for reading. */
void
grid_get_cell(struct grid *gd, u_int px, u_int py, struct grid_cell *gc)
{
	if (grid_check_y(gd, __func__, py) != 0 ||
	    px >= gd->linedata[py].cellsize)
		memcpy(gc, &grid_default_cell, sizeof *gc);
	else
		grid_get_cell1(&gd->linedata[py], px, gc);
}

/* Set cell at position. */
void
grid_set_cell(struct grid *gd, u_int px, u_int py, const struct grid_cell *gc)
{
	struct grid_line	*gl;
	struct grid_cell_entry	*gce;

	if (grid_check_y(gd, __func__, py) != 0)
		return;

	grid_expand_line(gd, py, px + 1, 8);

	gl = &gd->linedata[py];
	if (px + 1 > gl->cellused)
		gl->cellused = px + 1;

	gce = &gl->celldata[px];
	if (grid_need_extended_cell(gce, gc))
		grid_extended_cell(gl, gce, gc);
	else
		grid_store_cell(gce, gc, gc->data.data[0]);
}

/* Set padding at position. */
void
grid_set_padding(struct grid *gd, u_int px, u_int py)
{
	grid_set_cell(gd, px, py, &grid_padding_cell);
}

/* Set cells at position. */
void
grid_set_cells(struct grid *gd, u_int px, u_int py, const struct grid_cell *gc,
    const char *s, size_t slen)
{
	struct grid_line	*gl;
	struct grid_cell_entry	*gce;
	struct grid_extd_entry	*gee;
	u_int			 i;

	if (grid_check_y(gd, __func__, py) != 0)
		return;

	grid_expand_line(gd, py, px + slen, 8);

	gl = &gd->linedata[py];
	if (px + slen > gl->cellused)
		gl->cellused = px + slen;

	for (i = 0; i < slen; i++) {
		gce = &gl->celldata[px + i];
		if (grid_need_extended_cell(gce, gc)) {
			gee = grid_extended_cell(gl, gce, gc);
			gee->data = utf8_build_one(s[i]);
		} else
			grid_store_cell(gce, gc, s[i]);
	}
}

/* Clear area. */
void
grid_clear(struct grid *gd, u_int px, u_int py, u_int nx, u_int ny, u_int bg)
{
	struct grid_line	*gl;
	u_int			 xx, yy, ox, sx;

	if (nx == 0 || ny == 0)
		return;

	if (px == 0 && nx == gd->sx) {
		grid_clear_lines(gd, py, ny, bg);
		return;
	}

	if (grid_check_y(gd, __func__, py) != 0)
		return;
	if (grid_check_y(gd, __func__, py + ny - 1) != 0)
		return;

	for (yy = py; yy < py + ny; yy++) {
		gl = &gd->linedata[yy];

		sx = gd->sx;
		if (sx > gl->cellsize)
			sx = gl->cellsize;
		ox = nx;
		if (COLOUR_DEFAULT(bg)) {
			if (px > sx)
				continue;
			if (px + nx > sx)
				ox = sx - px;
		}

		grid_expand_line(gd, yy, px + ox, 8); /* default bg first */
		for (xx = px; xx < px + ox; xx++)
			grid_clear_cell(gd, xx, yy, bg);
	}
}

/* Clear lines. This just frees and truncates the lines. */
void
grid_clear_lines(struct grid *gd, u_int py, u_int ny, u_int bg)
{
	u_int	yy;

	if (ny == 0)
		return;

	if (grid_check_y(gd, __func__, py) != 0)
		return;
	if (grid_check_y(gd, __func__, py + ny - 1) != 0)
		return;

	for (yy = py; yy < py + ny; yy++) {
		grid_free_line(gd, yy);
		grid_empty_line(gd, yy, bg);
	}
	if (py != 0)
		gd->linedata[py - 1].flags &= ~GRID_LINE_WRAPPED;
}

/* Move a group of lines. */
void
grid_move_lines(struct grid *gd, u_int dy, u_int py, u_int ny, u_int bg)
{
	u_int	yy;

	if (ny == 0 || py == dy)
		return;

	if (grid_check_y(gd, __func__, py) != 0)
		return;
	if (grid_check_y(gd, __func__, py + ny - 1) != 0)
		return;
	if (grid_check_y(gd, __func__, dy) != 0)
		return;
	if (grid_check_y(gd, __func__, dy + ny - 1) != 0)
		return;

	/* Free any lines which are being replaced. */
	for (yy = dy; yy < dy + ny; yy++) {
		if (yy >= py && yy < py + ny)
			continue;
		grid_free_line(gd, yy);
	}
	if (dy != 0)
		gd->linedata[dy - 1].flags &= ~GRID_LINE_WRAPPED;

	memmove(&gd->linedata[dy], &gd->linedata[py],
	    ny * (sizeof *gd->linedata));

	/*
	 * Wipe any lines that have been moved (without freeing them - they are
	 * still present).
	 */
	for (yy = py; yy < py + ny; yy++) {
		if (yy < dy || yy >= dy + ny)
			grid_empty_line(gd, yy, bg);
	}
	if (py != 0 && (py < dy || py >= dy + ny))
		gd->linedata[py - 1].flags &= ~GRID_LINE_WRAPPED;
}

/* Move a group of cells. */
void
grid_move_cells(struct grid *gd, u_int dx, u_int px, u_int py, u_int nx,
    u_int bg)
{
	struct grid_line	*gl;
	u_int			 xx;

	if (nx == 0 || px == dx)
		return;

	if (grid_check_y(gd, __func__, py) != 0)
		return;
	gl = &gd->linedata[py];

	grid_expand_line(gd, py, px + nx, 8);
	grid_expand_line(gd, py, dx + nx, 8);
	memmove(&gl->celldata[dx], &gl->celldata[px],
	    nx * sizeof *gl->celldata);
	if (dx + nx > gl->cellused)
		gl->cellused = dx + nx;

	/* Wipe any cells that have been moved. */
	for (xx = px; xx < px + nx; xx++) {
		if (xx >= dx && xx < dx + nx)
			continue;
		grid_clear_cell(gd, xx, py, bg);
	}
}

/* Get ANSI foreground sequence. */
static size_t
grid_string_cells_fg(const struct grid_cell *gc, int *values)
{
	size_t	n;
	u_char	r, g, b;

	n = 0;
	if (gc->fg & COLOUR_FLAG_256) {
		values[n++] = 38;
		values[n++] = 5;
		values[n++] = gc->fg & 0xff;
	} else if (gc->fg & COLOUR_FLAG_RGB) {
		values[n++] = 38;
		values[n++] = 2;
		colour_split_rgb(gc->fg, &r, &g, &b);
		values[n++] = r;
		values[n++] = g;
		values[n++] = b;
	} else {
		switch (gc->fg) {
		case 0:
		case 1:
		case 2:
		case 3:
		case 4:
		case 5:
		case 6:
		case 7:
			values[n++] = gc->fg + 30;
			break;
		case 8:
			values[n++] = 39;
			break;
		case 90:
		case 91:
		case 92:
		case 93:
		case 94:
		case 95:
		case 96:
		case 97:
			values[n++] = gc->fg;
			break;
		}
	}
	return (n);
}

/* Get ANSI background sequence. */
static size_t
grid_string_cells_bg(const struct grid_cell *gc, int *values)
{
	size_t	n;
	u_char	r, g, b;

	n = 0;
	if (gc->bg & COLOUR_FLAG_256) {
		values[n++] = 48;
		values[n++] = 5;
		values[n++] = gc->bg & 0xff;
	} else if (gc->bg & COLOUR_FLAG_RGB) {
		values[n++] = 48;
		values[n++] = 2;
		colour_split_rgb(gc->bg, &r, &g, &b);
		values[n++] = r;
		values[n++] = g;
		values[n++] = b;
	} else {
		switch (gc->bg) {
		case 0:
		case 1:
		case 2:
		case 3:
		case 4:
		case 5:
		case 6:
		case 7:
			values[n++] = gc->bg + 40;
			break;
		case 8:
			values[n++] = 49;
			break;
		case 90:
		case 91:
		case 92:
		case 93:
		case 94:
		case 95:
		case 96:
		case 97:
			values[n++] = gc->bg + 10;
			break;
		}
	}
	return (n);
}

/* Get underscore colour sequence. */
static size_t
grid_string_cells_us(const struct grid_cell *gc, int *values)
{
	size_t	n;
	u_char	r, g, b;

	n = 0;
	if (gc->us & COLOUR_FLAG_256) {
		values[n++] = 58;
		values[n++] = 5;
		values[n++] = gc->us & 0xff;
	} else if (gc->us & COLOUR_FLAG_RGB) {
		values[n++] = 58;
		values[n++] = 2;
		colour_split_rgb(gc->us, &r, &g, &b);
		values[n++] = r;
		values[n++] = g;
		values[n++] = b;
	}
	return (n);
}

/* Add on SGR code. */
static void
grid_string_cells_add_code(char *buf, size_t len, u_int n, int *s, int *newc,
    int *oldc, size_t nnewc, size_t noldc, int escape_c0)
{
	u_int	i;
	char	tmp[64];

	if (nnewc != 0 &&
	    (nnewc != noldc ||
	    memcmp(newc, oldc, nnewc * sizeof newc[0]) != 0 ||
	    (n != 0 && s[0] == 0))) {
		if (escape_c0)
			strlcat(buf, "\\033[", len);
		else
			strlcat(buf, "\033[", len);
		for (i = 0; i < nnewc; i++) {
			if (i + 1 < nnewc)
				xsnprintf(tmp, sizeof tmp, "%d;", newc[i]);
			else
				xsnprintf(tmp, sizeof tmp, "%d", newc[i]);
			strlcat(buf, tmp, len);
		}
		strlcat(buf, "m", len);
	}
}

/*
 * Returns ANSI code to set particular attributes (colour, bold and so on)
 * given a current state.
 */
static void
grid_string_cells_code(const struct grid_cell *lastgc,
    const struct grid_cell *gc, char *buf, size_t len, int escape_c0)
{
	int	oldc[64], newc[64], s[128];
	size_t	noldc, nnewc, n, i;
	u_int	attr = gc->attr, lastattr = lastgc->attr;
	char	tmp[64];

	struct {
		u_int	mask;
		u_int	code;
	} attrs[] = {
		{ GRID_ATTR_BRIGHT, 1 },
		{ GRID_ATTR_DIM, 2 },
		{ GRID_ATTR_ITALICS, 3 },
		{ GRID_ATTR_UNDERSCORE, 4 },
		{ GRID_ATTR_BLINK, 5 },
		{ GRID_ATTR_REVERSE, 7 },
		{ GRID_ATTR_HIDDEN, 8 },
		{ GRID_ATTR_STRIKETHROUGH, 9 },
		{ GRID_ATTR_UNDERSCORE_2, 42 },
		{ GRID_ATTR_UNDERSCORE_3, 43 },
		{ GRID_ATTR_UNDERSCORE_4, 44 },
		{ GRID_ATTR_UNDERSCORE_5, 45 },
		{ GRID_ATTR_OVERLINE, 53 },
	};
	n = 0;

	/* If any attribute is removed, begin with 0. */
	for (i = 0; i < nitems(attrs); i++) {
		if (((~attr & attrs[i].mask) &&
		    (lastattr & attrs[i].mask)) ||
		    (lastgc->us != 0 && gc->us == 0)) {
			s[n++] = 0;
			lastattr &= GRID_ATTR_CHARSET;
			break;
		}
	}
	/* For each attribute that is newly set, add its code. */
	for (i = 0; i < nitems(attrs); i++) {
		if ((attr & attrs[i].mask) && !(lastattr & attrs[i].mask))
			s[n++] = attrs[i].code;
	}

	/* Write the attributes. */
	*buf = '\0';
	if (n > 0) {
		if (escape_c0)
			strlcat(buf, "\\033[", len);
		else
			strlcat(buf, "\033[", len);
		for (i = 0; i < n; i++) {
			if (s[i] < 10)
				xsnprintf(tmp, sizeof tmp, "%d", s[i]);
			else {
				xsnprintf(tmp, sizeof tmp, "%d:%d", s[i] / 10,
				    s[i] % 10);
			}
			strlcat(buf, tmp, len);
			if (i + 1 < n)
				strlcat(buf, ";", len);
		}
		strlcat(buf, "m", len);
	}

	/* If the foreground colour changed, write its parameters. */
	nnewc = grid_string_cells_fg(gc, newc);
	noldc = grid_string_cells_fg(lastgc, oldc);
	grid_string_cells_add_code(buf, len, n, s, newc, oldc, nnewc, noldc,
	    escape_c0);

	/* If the background colour changed, append its parameters. */
	nnewc = grid_string_cells_bg(gc, newc);
	noldc = grid_string_cells_bg(lastgc, oldc);
	grid_string_cells_add_code(buf, len, n, s, newc, oldc, nnewc, noldc,
	    escape_c0);

	/* If the underscore colour changed, append its parameters. */
	nnewc = grid_string_cells_us(gc, newc);
	noldc = grid_string_cells_us(lastgc, oldc);
	grid_string_cells_add_code(buf, len, n, s, newc, oldc, nnewc, noldc,
	    escape_c0);

	/* Append shift in/shift out if needed. */
	if ((attr & GRID_ATTR_CHARSET) && !(lastattr & GRID_ATTR_CHARSET)) {
		if (escape_c0)
			strlcat(buf, "\\016", len); /* SO */
		else
			strlcat(buf, "\016", len);  /* SO */
	}
	if (!(attr & GRID_ATTR_CHARSET) && (lastattr & GRID_ATTR_CHARSET)) {
		if (escape_c0)
			strlcat(buf, "\\017", len); /* SI */
		else
			strlcat(buf, "\017", len);  /* SI */
	}
}

/* Convert cells into a string. */
char *
grid_string_cells(struct grid *gd, u_int px, u_int py, u_int nx,
    struct grid_cell **lastgc, int with_codes, int escape_c0, int trim)
{
	struct grid_cell	 gc;
	static struct grid_cell	 lastgc1;
	const char		*data;
	char			*buf, code[128];
	size_t			 len, off, size, codelen;
	u_int			 xx;
	const struct grid_line	*gl;

	if (lastgc != NULL && *lastgc == NULL) {
		memcpy(&lastgc1, &grid_default_cell, sizeof lastgc1);
		*lastgc = &lastgc1;
	}

	len = 128;
	buf = xmalloc(len);
	off = 0;

	gl = grid_peek_line(gd, py);
	for (xx = px; xx < px + nx; xx++) {
		if (gl == NULL || xx >= gl->cellused)
			break;
		grid_get_cell(gd, xx, py, &gc);
		if (gc.flags & GRID_FLAG_PADDING)
			continue;

		if (with_codes) {
			grid_string_cells_code(*lastgc, &gc, code, sizeof code,
			    escape_c0);
			codelen = strlen(code);
			memcpy(*lastgc, &gc, sizeof **lastgc);
		} else
			codelen = 0;

		data = gc.data.data;
		size = gc.data.size;
		if (escape_c0 && size == 1 && *data == '\\') {
			data = "\\\\";
			size = 2;
		}

		while (len < off + size + codelen + 1) {
			buf = xreallocarray(buf, 2, len);
			len *= 2;
		}

		if (codelen != 0) {
			memcpy(buf + off, code, codelen);
			off += codelen;
		}
		memcpy(buf + off, data, size);
		off += size;
	}

	if (trim) {
		while (off > 0 && buf[off - 1] == ' ')
			off--;
	}
	buf[off] = '\0';

	return (buf);
}

/*
 * Duplicate a set of lines between two grids. Both source and destination
 * should be big enough.
 */
void
grid_duplicate_lines(struct grid *dst, u_int dy, struct grid *src, u_int sy,
    u_int ny)
{
	struct grid_line	*dstl, *srcl;
	u_int			 yy;

	if (dy + ny > dst->hsize + dst->sy)
		ny = dst->hsize + dst->sy - dy;
	if (sy + ny > src->hsize + src->sy)
		ny = src->hsize + src->sy - sy;
	grid_free_lines(dst, dy, ny);

	for (yy = 0; yy < ny; yy++) {
		srcl = &src->linedata[sy];
		dstl = &dst->linedata[dy];

		memcpy(dstl, srcl, sizeof *dstl);
		if (srcl->cellsize != 0) {
			dstl->celldata = xreallocarray(NULL,
			    srcl->cellsize, sizeof *dstl->celldata);
			memcpy(dstl->celldata, srcl->celldata,
			    srcl->cellsize * sizeof *dstl->celldata);
		} else
			dstl->celldata = NULL;
		if (srcl->extdsize != 0) {
			dstl->extdsize = srcl->extdsize;
			dstl->extddata = xreallocarray(NULL, dstl->extdsize,
			    sizeof *dstl->extddata);
			memcpy(dstl->extddata, srcl->extddata, dstl->extdsize *
			    sizeof *dstl->extddata);
		} else
			dstl->extddata = NULL;

		sy++;
		dy++;
	}
}

/* Mark line as dead. */
static void
grid_reflow_dead(struct grid_line *gl)
{
	memset(gl, 0, sizeof *gl);
	gl->flags = GRID_LINE_DEAD;
}

/* Add lines, return the first new one. */
static struct grid_line *
grid_reflow_add(struct grid *gd, u_int n)
{
	struct grid_line	*gl;
	u_int			 sy = gd->sy + n;

	gd->linedata = xreallocarray(gd->linedata, sy, sizeof *gd->linedata);
	gl = &gd->linedata[gd->sy];
	memset(gl, 0, n * (sizeof *gl));
	gd->sy = sy;
	return (gl);
}

/* Move a line across. */
static struct grid_line *
grid_reflow_move(struct grid *gd, struct grid_line *from)
{
	struct grid_line	*to;

	to = grid_reflow_add(gd, 1);
	memcpy(to, from, sizeof *to);
	grid_reflow_dead(from);
	return (to);
}

/* Join line below onto this one. */
static void
grid_reflow_join(struct grid *target, struct grid *gd, u_int sx, u_int yy,
    u_int width, int already)
{
	struct grid_line	*gl, *from = NULL;
	struct grid_cell	 gc;
	u_int			 lines, left, i, to, line, want = 0;
	u_int			 at;
	int			 wrapped = 1;

	/*
	 * Add a new target line.
	 */
	if (!already) {
		to = target->sy;
		gl = grid_reflow_move(target, &gd->linedata[yy]);
	} else {
		to = target->sy - 1;
		gl = &target->linedata[to];
	}
	at = gl->cellused;

	/*
	 * Loop until no more to consume or the target line is full.
	 */
	lines = 0;
	for (;;) {
		/*
		 * If this is now the last line, there is nothing more to be
		 * done.
		 */
		if (yy + 1 + lines == gd->hsize + gd->sy)
			break;
		line = yy + 1 + lines;

		/* If the next line is empty, skip it. */
		if (~gd->linedata[line].flags & GRID_LINE_WRAPPED)
			wrapped = 0;
		if (gd->linedata[line].cellused == 0) {
			if (!wrapped)
				break;
			lines++;
			continue;
		}

		/*
		 * Is the destination line now full? Copy the first character
		 * separately because we need to leave "from" set to the last
		 * line if this line is full.
		 */
		grid_get_cell1(&gd->linedata[line], 0, &gc);
		if (width + gc.data.width > sx)
			break;
		width += gc.data.width;
		grid_set_cell(target, at, to, &gc);
		at++;

		/* Join as much more as possible onto the current line. */
		from = &gd->linedata[line];
		for (want = 1; want < from->cellused; want++) {
			grid_get_cell1(from, want, &gc);
			if (width + gc.data.width > sx)
				break;
			width += gc.data.width;

			grid_set_cell(target, at, to, &gc);
			at++;
		}
		lines++;

		/*
		 * If this line wasn't wrapped or we didn't consume the entire
		 * line, don't try to join any further lines.
		 */
		if (!wrapped || want != from->cellused || width == sx)
			break;
	}
	if (lines == 0)
		return;

	/*
	 * If we didn't consume the entire final line, then remove what we did
	 * consume. If we consumed the entire line and it wasn't wrapped,
	 * remove the wrap flag from this line.
	 */
	left = from->cellused - want;
	if (left != 0) {
		grid_move_cells(gd, 0, want, yy + lines, left, 8);
		from->cellsize = from->cellused = left;
		lines--;
	} else if (!wrapped)
		gl->flags &= ~GRID_LINE_WRAPPED;

	/* Remove the lines that were completely consumed. */
	for (i = yy + 1; i < yy + 1 + lines; i++) {
		free(gd->linedata[i].celldata);
		free(gd->linedata[i].extddata);
		grid_reflow_dead(&gd->linedata[i]);
	}

	/* Adjust scroll position. */
	if (gd->hscrolled > to + lines)
		gd->hscrolled -= lines;
	else if (gd->hscrolled > to)
		gd->hscrolled = to;
}

/* Split this line into several new ones */
static void
grid_reflow_split(struct grid *target, struct grid *gd, u_int sx, u_int yy,
    u_int at)
{
	struct grid_line	*gl = &gd->linedata[yy], *first;
	struct grid_cell	 gc;
	u_int			 line, lines, width, i, xx;
	u_int			 used = gl->cellused;
	int			 flags = gl->flags;

	/* How many lines do we need to insert? We know we need at least two. */
	if (~gl->flags & GRID_LINE_EXTENDED)
		lines = 1 + (gl->cellused - 1) / sx;
	else {
		lines = 2;
		width = 0;
		for (i = at; i < used; i++) {
			grid_get_cell1(gl, i, &gc);
			if (width + gc.data.width > sx) {
				lines++;
				width = 0;
			}
			width += gc.data.width;
		}
	}

	/* Insert new lines. */
	line = target->sy + 1;
	first = grid_reflow_add(target, lines);

	/* Copy sections from the original line. */
	width = 0;
	xx = 0;
	for (i = at; i < used; i++) {
		grid_get_cell1(gl, i, &gc);
		if (width + gc.data.width > sx) {
			target->linedata[line].flags |= GRID_LINE_WRAPPED;

			line++;
			width = 0;
			xx = 0;
		}
		width += gc.data.width;
		grid_set_cell(target, xx, line, &gc);
		xx++;
	}
	if (flags & GRID_LINE_WRAPPED)
		target->linedata[line].flags |= GRID_LINE_WRAPPED;

	/* Move the remainder of the original line. */
	gl->cellsize = gl->cellused = at;
	gl->flags |= GRID_LINE_WRAPPED;
	memcpy(first, gl, sizeof *first);
	grid_reflow_dead(gl);

	/* Adjust the scroll position. */
	if (yy <= gd->hscrolled)
		gd->hscrolled += lines - 1;

	/*
	 * If the original line had the wrapped flag and there is still space
	 * in the last new line, try to join with the next lines.
	 */
	if (width < sx && (flags & GRID_LINE_WRAPPED))
		grid_reflow_join(target, gd, sx, yy, width, 1);
}

/* Reflow lines on grid to new width. */
void
grid_reflow(struct grid *gd, u_int sx)
{
	struct grid		*target;
	struct grid_line	*gl;
	struct grid_cell	 gc;
	u_int			 yy, width, i, at;

	/*
	 * Create a destination grid. This is just used as a container for the
	 * line data and may not be fully valid.
	 */
	target = grid_create(gd->sx, 0, 0);

	/*
	 * Loop over each source line.
	 */
	for (yy = 0; yy < gd->hsize + gd->sy; yy++) {
		gl = &gd->linedata[yy];
		if (gl->flags & GRID_LINE_DEAD)
			continue;

		/*
		 * Work out the width of this line. at is the point at which
		 * the available width is hit, and width is the full line
		 * width.
		 */
		at = width = 0;
		if (~gl->flags & GRID_LINE_EXTENDED) {
			width = gl->cellused;
			if (width > sx)
				at = sx;
			else
				at = width;
		} else {
			for (i = 0; i < gl->cellused; i++) {
				grid_get_cell1(gl, i, &gc);
				if (at == 0 && width + gc.data.width > sx)
					at = i;
				width += gc.data.width;
			}
		}

		/*
		 * If the line is exactly right, just move it across
		 * unchanged.
		 */
		if (width == sx) {
			grid_reflow_move(target, gl);
			continue;
		}

		/*
		 * If the line is too big, it needs to be split, whether or not
		 * it was previously wrapped.
		 */
		if (width > sx) {
			grid_reflow_split(target, gd, sx, yy, at);
			continue;
		}

		/*
		 * If the line was previously wrapped, join as much as possible
		 * of the next line.
		 */
		if (gl->flags & GRID_LINE_WRAPPED)
			grid_reflow_join(target, gd, sx, yy, width, 0);
		else
			grid_reflow_move(target, gl);
	}

	/*
	 * Replace the old grid with the new.
	 */
	if (target->sy < gd->sy)
		grid_reflow_add(target, gd->sy - target->sy);
	gd->hsize = target->sy - gd->sy;
	if (gd->hscrolled > gd->hsize)
		gd->hscrolled = gd->hsize;
	free(gd->linedata);
	gd->linedata = target->linedata;
	free(target);
}

/* Convert to position based on wrapped lines. */
void
grid_wrap_position(struct grid *gd, u_int px, u_int py, u_int *wx, u_int *wy)
{
	u_int	ax = 0, ay = 0, yy;

	for (yy = 0; yy < py; yy++) {
		if (gd->linedata[yy].flags & GRID_LINE_WRAPPED)
			ax += gd->linedata[yy].cellused;
		else {
			ax = 0;
			ay++;
		}
	}
	if (px >= gd->linedata[yy].cellused)
		ax = UINT_MAX;
	else
		ax += px;
	*wx = ax;
	*wy = ay;
}

/* Convert position based on wrapped lines back. */
void
grid_unwrap_position(struct grid *gd, u_int *px, u_int *py, u_int wx, u_int wy)
{
	u_int	yy, ay = 0;

	for (yy = 0; yy < gd->hsize + gd->sy - 1; yy++) {
		if (ay == wy)
			break;
		if (~gd->linedata[yy].flags & GRID_LINE_WRAPPED)
			ay++;
	}

	/*
	 * yy is now 0 on the unwrapped line which contains wx. Walk forwards
	 * until we find the end or the line now containing wx.
	 */
	if (wx == UINT_MAX) {
		while (gd->linedata[yy].flags & GRID_LINE_WRAPPED)
			yy++;
		wx = gd->linedata[yy].cellused;
	} else {
		while (gd->linedata[yy].flags & GRID_LINE_WRAPPED) {
			if (wx < gd->linedata[yy].cellused)
				break;
			wx -= gd->linedata[yy].cellused;
			yy++;
		}
	}
	*px = wx;
	*py = yy;
}

/* Get length of line. */
u_int
grid_line_length(struct grid *gd, u_int py)
{
	struct grid_cell	gc;
	u_int			px;

	px = grid_get_line(gd, py)->cellsize;
	if (px > gd->sx)
		px = gd->sx;
	while (px > 0) {
		grid_get_cell(gd, px - 1, py, &gc);
		if ((gc.flags & GRID_FLAG_PADDING) ||
		    gc.data.size != 1 ||
		    *gc.data.data != ' ')
			break;
		px--;
	}
	return (px);
}