/*
 * Copyright (c) 2008, Natacha Porté
 * Copyright (c) 2011, Vicent Martí
 * Copyright (c) 2014, Xavier Mendez, Devin Torres and the Hoedown authors
 * Copyright (c) Kristaps Dzonsons <kristaps@bsd.lv>
 *
 * 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 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 "config.h"

#if HAVE_SYS_QUEUE
# include <sys/queue.h>
#endif

#include <assert.h>
#include <ctype.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "lowdown.h"
#include "extern.h"

enum	nfont {
	NFONT_ITALIC = 0, /* italic */
	NFONT_BOLD, /* bold */
	NFONT_FIXED, /* fixed-width */
	NFONT__MAX
};

struct 	nroff {
	struct hentryq	 	  headers_used; /* headers we've seen */
	int			  man; /* whether man(7) */
	int			  post_para; /* for choosing PP/LP */
	unsigned int		  flags; /* output flags */
	ssize_t			  headers_offs; /* header offset */
	enum nfont		  fonts[NFONT__MAX]; /* see bqueue_font() */
	struct bnodeq		**foots; /* footnotes */
	size_t			  footsz; /* footnote size */
	size_t			  footpos; /* footnote position (-tms) */
	size_t			  footdepth; /* printing/parsing footnotes */
	size_t			  indent; /* indentation width */
	const char		 *cr; /* fixed-width font */
	const char		 *cb; /* fixed-width bold font */
	const char		 *ci; /* fixed-width italic font */
	const char		 *cbi; /* fixed-width bold-italic font */
};

enum	bscope {
	BSCOPE_BLOCK = 0,
	BSCOPE_SPAN,
	BSCOPE_SEMI,
	BSCOPE_SEMI_CLOSE,
	BSCOPE_LITERAL,
	BSCOPE_FONT,
	BSCOPE_COLOUR
};

/*
 * Instead of writing directly into the output buffer, we write
 * temporarily into bnodes, which are converted into output.  These
 * nodes are aware of whether they need surrounding newlines.
 */
struct	bnode {
	char				*nbuf; /* (safe) 1st data */
	char				*buf; /* (unsafe) 2nd data */
	char				*nargs; /* (safe) 1st args */
	char				*args; /* (unsafe) 2nd args */
	int				 close; /* BNODE_COLOUR/FONT */
	int				 tblhack; /* BSCOPE_SPAN */
        int				 headerhack; /* BSCOPE_BLOCK */
	enum bscope			 scope; /* scope */
	unsigned int			 font; /* if BNODE_FONT */
#define	BFONT_ITALIC			 0x01
#define	BFONT_BOLD			 0x02
#define	BFONT_FIXED			 0x04
	unsigned int			 colour; /* if BNODE_COLOUR */
#define	BFONT_BLUE			 0x01
#define	BFONT_RED			 0x02
	TAILQ_ENTRY(bnode)		 entries;
};

TAILQ_HEAD(bnodeq, bnode);

/*
 * Escape unsafe text into roff output such that no roff features are
 * invoked by the text (macros, escapes, etc.).
 * If "oneline" is non-zero, newlines are replaced with spaces.
 * If "literal", doesn't strip leading space.
 * Return zero on failure, non-zero on success.
 */
static int
hesc_nroff(struct lowdown_buf *ob, const char *data, size_t size,
    int oneline, int literal, int esc)
{
	size_t	 	i = 0;
	unsigned char	ch;

	if (size == 0)
		return 1;

	if (!esc && oneline) {
		assert(!literal);
		for (i = 0; i < size; i++) {
			ch = data[i] == '\n' ? ' ' : data[i];
			if (!hbuf_putc(ob, ch))
				return 0;
			if (ch != ' ')
				continue;
			while (i < size && isspace((unsigned char)data[i]))
				i++;
			i--;
		}
		return 1;
	} else if (!esc)
		return hbuf_put(ob, data, size);

	/* Strip leading whitespace. */

	if (!literal && ob->size > 0 && ob->data[ob->size - 1] == '\n')
		while (i < size && (data[i] == ' ' || data[i] == '\n'))
			i++;

	/*
	 * According to mandoc_char(7), we need to escape the backtick,
	 * single apostrophe, and tilde or else they'll be considered as
	 * special Unicode output.
	 * Slashes need to be escaped too.
	 * We also escape double-quotes because this text might be used
	 * within quoted macro arguments.
	 */

	for ( ; i < size; i++)
		switch (data[i]) {
		case '^':
			if (!HBUF_PUTSL(ob, "\\(ha"))
				return 0;
			break;
		case '~':
			if (!HBUF_PUTSL(ob, "\\(ti"))
				return 0;
			break;
		case '`':
			if (!HBUF_PUTSL(ob, "\\(ga"))
				return 0;
			break;
		case '"':
			if (!HBUF_PUTSL(ob, "\\(dq"))
				return 0;
			break;
		case '\n':
			if (!hbuf_putc(ob, oneline ? ' ' : '\n'))
				return 0;
			if (literal)
				break;

			/* Prevent leading spaces on the line. */

			while (i + 1 < size && 
			       (data[i + 1] == ' ' || 
				data[i + 1] == '\n'))
				i++;
			break;
		case '\\':
			if (!HBUF_PUTSL(ob, "\\e"))
				return 0;
			break;
		case '\'':
		case '.':
			if (!oneline &&
			    ob->size > 0 && 
			    ob->data[ob->size - 1] == '\n' &&
			    !HBUF_PUTSL(ob, "\\&"))
				return 0;
			/* FALLTHROUGH */
		default:
			if (!hbuf_putc(ob, data[i]))
				return 0;
			break;
		}

	return 1;
}

static const char *
nstate_colour_buf(unsigned int ft)
{
	static char 	 fonts[10];

	fonts[0] = '\0';
	if (ft == BFONT_BLUE)
		strlcat(fonts, "blue", sizeof(fonts));
	else if (ft == BFONT_RED)
		strlcat(fonts, "red", sizeof(fonts));
	else
		strlcat(fonts, "black", sizeof(fonts));
	return fonts;
}

/*
 * For compatibility with traditional troff, return non-block font code
 * using the correct sequence of \fX, \f(xx, and \f[xxx].
 */
static int
nstate_font(const struct nroff *st, struct lowdown_buf *ob,
    unsigned int ft, int enclose)
{
	const char	*font = NULL;
	char		 fonts[3];
	char		*cp = fonts;
	size_t		 sz;

	if (ft & BFONT_FIXED) {
		if ((ft & BFONT_BOLD) && (ft & BFONT_ITALIC))
			font = st->cbi;
		else if (ft & BFONT_BOLD)
			font = st->cb;
		else if (ft & BFONT_ITALIC)
			font = st->ci;
		else
			font = st->cr;
	} else {
		font = cp = fonts;
		if (ft & BFONT_BOLD)
			(*cp++) = 'B';
		if (ft & BFONT_ITALIC)
			(*cp++) = 'I';
		if (ft == 0)
			(*cp++) = 'R';
		*cp = '\0';
	}

	assert(font != NULL);
	sz = strlen(font);
	assert(sz > 0);

	if (!enclose || sz == 1)
		return hbuf_puts(ob, font);

	if (sz > 2)
		return HBUF_PUTSL(ob, "[") &&
		    hbuf_puts(ob, font) && HBUF_PUTSL(ob, "]");

	return HBUF_PUTSL(ob, "(") && hbuf_puts(ob, font);
}

static int
bqueue_colour(struct bnodeq *bq, enum lowdown_chng chng, int close)
{
	struct bnode	*bn;

	if ((bn = calloc(1, sizeof(struct bnode))) == NULL)
		return 0;
	TAILQ_INSERT_TAIL(bq, bn, entries);
	bn->scope = BSCOPE_COLOUR;
	bn->close = close;
	bn->colour = close ? 0 :
		chng == LOWDOWN_CHNG_INSERT ? 
		BFONT_BLUE : BFONT_RED;
	return 1;
}

static int
bqueue_font(const struct nroff *st, struct bnodeq *bq, int close)
{
	struct bnode	*bn;

	if ((bn = calloc(1, sizeof(struct bnode))) == NULL)
		return 0;
	TAILQ_INSERT_TAIL(bq, bn, entries);
	bn->scope = BSCOPE_FONT;
	bn->close = close;
	if (st->fonts[NFONT_FIXED])
		bn->font |= BFONT_FIXED;
	if (st->fonts[NFONT_BOLD])
		bn->font |= BFONT_BOLD;
	if (st->fonts[NFONT_ITALIC])
		bn->font |= BFONT_ITALIC;
	return 1;
}

static struct bnode *
bqueue_node(struct bnodeq *bq, enum bscope scope, const char *text)
{
	struct bnode	*bn;

	if ((bn = calloc(1, sizeof(struct bnode))) == NULL)
		return NULL;
	bn->scope = scope;
	if (text != NULL && (bn->nbuf = strdup(text)) == NULL) {
		free(bn);
		return NULL;
	}
	TAILQ_INSERT_TAIL(bq, bn, entries);
	return bn;
}

static struct bnode *
bqueue_span(struct bnodeq *bq, const char *text)
{

	return bqueue_node(bq, BSCOPE_SPAN, text);
}

static struct bnode *
bqueue_block(struct nroff *st, struct bnodeq *bq, const char *text)
{

	return bqueue_node(bq, BSCOPE_BLOCK, text);
}

static void
bnode_free(struct bnode *bn)
{

	free(bn->args);
	free(bn->nargs);
	free(bn->nbuf);
	free(bn->buf);
	free(bn);
}

static void
bqueue_free(struct bnodeq *bq)
{
	struct bnode	*bn;

	while ((bn = TAILQ_FIRST(bq)) != NULL) {
		TAILQ_REMOVE(bq, bn, entries);
		bnode_free(bn);
	}
}

static void
bqueue_strip_paras(struct bnodeq *bq)
{
	struct bnode	*bn;

	while ((bn = TAILQ_FIRST(bq)) != NULL) {
		if (bn->scope != BSCOPE_BLOCK || bn->nbuf == NULL)
			break;
		if (strcmp(bn->nbuf, ".PP") &&
		    strcmp(bn->nbuf, ".IP") &&
		    strcmp(bn->nbuf, ".LP"))
			break;
		TAILQ_REMOVE(bq, bn, entries);
		bnode_free(bn);
	}
}

/**
 * Flush nodes from "bq" into "ob".  This does not remove any nodes from
 * "bq" (hence it being const).
 */
static int
bqueue_flush(const struct nroff *st, struct lowdown_buf *ob,
    const struct bnodeq *bq)
{
	const struct bnode	*bn, *chk, *next;
	const char		*cp;
	int		 	 nextblk;
	char			 trailingchar;

	TAILQ_FOREACH(bn, bq, entries) {
		nextblk = 0;

		/*
		 * The semi-block macro is a span (within text content),
		 * but has block syntax.  If there's no leading space,
		 * use "\c" to inhibit whitespace prior to the macro.
		 */

		if (bn->scope == BSCOPE_SEMI &&
		    ob->size > 0 && 
		    ob->data[ob->size - 1] != '\n' &&
		    !hbuf_puts(ob, "\\c"))
			return 0;

		/* 
		 * Block/semi scopes start with a newline.
		 * Also have colours use their own block, as otherwise
		 * (bugs in groff?) inline colour selection after a
		 * hyperlink macro causes line breaks.
		 * Besides, having spaces around changing colour, which
		 * indicates differences, improves readability.
		 */

		if (bn->scope == BSCOPE_BLOCK ||
		    bn->scope == BSCOPE_SEMI ||
		    bn->scope == BSCOPE_SEMI_CLOSE ||
		    bn->scope == BSCOPE_COLOUR) {
			if (ob->size > 0 && 
			    ob->data[ob->size - 1] != '\n' &&
			    !hbuf_putc(ob, '\n'))
				return 0;
			nextblk = 1;
		}

		/* 
		 * Fonts can either be macros or inline depending upon
		 * where they set relative to a macro block.
		 */

		if (bn->scope == BSCOPE_FONT) {
			chk = bn->close ?
				TAILQ_PREV(bn, bnodeq, entries) :
				TAILQ_NEXT(bn, entries);
			if (chk != NULL && 
			    (chk->scope == BSCOPE_SEMI ||
			     chk->scope == BSCOPE_SEMI_CLOSE ||
			     chk->scope == BSCOPE_BLOCK)) {
				if (ob->size > 0 && 
				    ob->data[ob->size - 1] != '\n' &&
				    !hbuf_putc(ob, '\n'))
					return 0;
				nextblk = 1;
			}
		}

		/* Print font and colour escapes. */

		if (bn->scope == BSCOPE_FONT && nextblk) {
			if (!HBUF_PUTSL(ob, ".ft "))
				return 0;
			if (!nstate_font(st, ob, bn->font, 0))
				return 0;
		} else if (bn->scope == BSCOPE_FONT) {
			if (!HBUF_PUTSL(ob, "\\f"))
				return 0;
			if (!nstate_font(st, ob, bn->font, 1))
				return 0;
		} else if (bn->scope == BSCOPE_COLOUR) {
			assert(nextblk);
			if (!hbuf_printf(ob, ".gcolor %s", 
			    nstate_colour_buf(bn->colour)))
				return 0;
		}

		/* 
		 * A "tblhack" is used by a span macro to indicate
		 * that it should start its own line, but that data
		 * continues to flow after it.  This is only used in
		 * tables with T}, at this point.
		 */

		if (bn->scope == BSCOPE_SPAN && bn->tblhack &&
		    ob->size > 0 && ob->data[ob->size - 1] != '\n')
			if (!hbuf_putc(ob, '\n'))
				return 0;

		/*
		 * If we're a span, double-check to see whether we
		 * should introduce a line with an escape.
		 */

		if (bn->scope == BSCOPE_SPAN &&
		    bn->nbuf != NULL && ob->size > 0 &&
		    ob->data[ob->size - 1] == '\n' &&
		    (bn->nbuf[0] == '.' || bn->nbuf[0] == '\'') &&
		    !HBUF_PUTSL(ob, "\\&"))
			return 0;

		/* Safe data need not be escaped. */

		if (bn->nbuf != NULL && !hbuf_puts(ob, bn->nbuf))
			return 0;

		/* Unsafe data must be escaped. */

		if (bn->scope == BSCOPE_LITERAL) {
			assert(bn->buf != NULL);
			if (!hesc_nroff(ob, bn->buf,
			    strlen(bn->buf), 0, 1, 1))
				return 0;
		} else if (bn->buf != NULL)
			if (!hesc_nroff(ob, bn->buf,
			    strlen(bn->buf), 0, 0, 1))
				return 0;

		/*
		 * Special handling of the semi-blocks, specifically
		 * either ".pdfhref" or ".UE", where the next text has
		 * no leading space.  In this case, we need to terminate
		 * the semi-block macro with "\c" to inhibit whitespace.
		 */

		if ((next = TAILQ_NEXT(bn, entries)) != NULL &&
		    next->scope == BSCOPE_SPAN &&
		    next->buf != NULL &&
		    next->buf[0] != ' ' &&
		    next->buf[0] != '\n') {
			if (!st->man &&
			    bn->scope == BSCOPE_SEMI &&
			    !HBUF_PUTSL(ob, " -A \"\\c\""))
				return 0;
			if (st->man &&
			    bn->scope == BSCOPE_SEMI_CLOSE &&
			    !HBUF_PUTSL(ob, " \\c"))
				return 0;
		}

		/*
		 * FIXME: BSCOPE_SEMI_CLOSE in a font context needs to
		 * reopen the font (e.g., \fB), as it internally will
		 * unset any font context.
		 */

		/* 
		 * Macro arguments follow after space.  For links, these
		 * must all be printed on the same line.
		 */

		if (bn->nargs != NULL &&
		    (bn->scope == BSCOPE_BLOCK ||
		     bn->scope == BSCOPE_SEMI)) {
			assert(nextblk);
			if (!hbuf_putc(ob, ' '))
				return 0;
			for (cp = bn->nargs; *cp != '\0'; cp++)
				if (!hbuf_putc(ob, 
				    *cp == '\n' ? ' ' : *cp))
					return 0;
		}

		if (bn->args != NULL) {
			assert(nextblk);
			assert(bn->scope == BSCOPE_BLOCK ||
				bn->scope == BSCOPE_SEMI);
			if (!hbuf_putc(ob, ' '))
				return 0;
			if (!hesc_nroff(ob, bn->args,
			    strlen(bn->args), 1, 0, 1))
				return 0;
		}

		/*
		 * The "headerhack" is used by SH block macros to
		 * indicate that their children are all normal text or
		 * entities, and so to output the content on the same
		 * line as the SH macro.  This is a hack because man(7)
		 * specifically allows for next-line content; however,
		 * buggy software (e.g., Mac OS X's makewhatis) don't
		 * correctly parse empty SH properly.
		 */

		trailingchar = bn->headerhack ? ' ' : '\n';

		if (nextblk && ob->size > 0 && 
		    ob->data[ob->size - 1] != trailingchar &&
		    !hbuf_putc(ob, trailingchar))
			return 0;
	}

	return 1;
}

/*
 * Convert a link into a short-link and place the escaped output into a
 * returned string.
 * Returns NULL on memory allocation failure.
 */
static char *
hbuf2shortlink(const struct lowdown_buf *link)
{
	struct lowdown_buf	*tmp = NULL, *slink = NULL;
	char			*ret = NULL;

	if ((tmp = hbuf_new(32)) == NULL)
		goto out;
	if ((slink = hbuf_new(32)) == NULL)
		goto out;
	if (!hbuf_shortlink(tmp, link))
		goto out;
	if (!hesc_nroff(slink, tmp->data, tmp->size, 1, 0, 1))
		goto out;
	ret = strndup(slink->data, slink->size);
out:
	hbuf_free(tmp);
	hbuf_free(slink);
	return ret;
}

/**
 * Escape a URL.  Return FALSE on error (memory), TRUE on success.
 */
static int
putlinkhref(struct lowdown_buf *ob, const struct lowdown_buf *link,
    enum halink_type *type)
{
	size_t	 i = 0;

	if (type != NULL && *type == HALINK_EMAIL &&
	    hbuf_strprefix(link, "mailto:"))
		i = strlen("mailto:");

	for ( ; i < link->size; i++) {
		if (!isprint((unsigned char)link->data[i]) ||
		    strchr("<>\\^`{|}\"", link->data[i]) != NULL) {
			if (!hbuf_printf(ob, "%%%.2X", link->data[i]))
				return 0;
		} else if (!hbuf_putc(ob, link->data[i]))
			return 0;
	}

	return 1;
}

/*
 * Manage hypertext linking with the groff "pdfhref" macro, UR/UE, or
 * simply using italics.  Return FALSE on error (memory), TRUE on
 * success.
 */
static int
putlink(struct bnodeq *obq, struct nroff *st, 
    const struct lowdown_node *n, const struct lowdown_buf *link, 
    const struct lowdown_buf *id, struct bnodeq *bq,
    enum halink_type type)
{
	struct lowdown_buf	*ob = NULL;
	struct bnode		*bn;
	int			 rc = 0, classic = 0;

	classic = !(st->flags & LOWDOWN_NROFF_GROFF);

	if (type != HALINK_EMAIL && hbuf_strprefix(link, "mailto:"))
		type = HALINK_EMAIL;

	/*
	 * XXX: override as classic if -tman and in a section header or
	 * definition title.
	 * This is because UR/UE or MT/ME don't work properly in at
	 * least mandoc when invoked with link text: the parser things
	 * that the content is the next line, then puts all UE content
	 * in the subsequent body.
	 */

	if (st->man && (st->flags & LOWDOWN_NROFF_GROFF))
		for ( ; n != NULL && !classic; n = n->parent)
			if (n->type == LOWDOWN_HEADER ||
			    n->type == LOWDOWN_DEFINITION_TITLE)
				classic = 1;

	if (classic) {
		/*
		 * For output without .pdfhref ("groff") or UR/UE,
		 * format the link as-is, with text then link, or use
		 * the various shorteners.
		 */
		if (bq == NULL) {
			/*
			 * No link content: format the URL according to
			 * the user's style and output it in italics.
			 */
			st->fonts[NFONT_ITALIC]++;
			if (!bqueue_font(st, obq, 0))
				goto out;
			if ((bn = bqueue_span(obq, NULL)) == NULL)
				goto out;
			if (st->flags & LOWDOWN_NROFF_SHORTLINK) {
				bn->nbuf = hbuf2shortlink(link);
				if (bn->nbuf == NULL)
					goto out;
			} else {
				bn->buf = strndup(link->data, link->size);
				if (bn->buf == NULL)
					goto out;
			}
			st->fonts[NFONT_ITALIC]--;
			if (!bqueue_font(st, obq, 1))
				goto out;
			rc = 1;
			goto out;
		}

		/* Link content exists: output it in bold. */

		st->fonts[NFONT_BOLD]++;
		if (!bqueue_font(st, obq, 0))
			goto out;
		TAILQ_CONCAT(obq, bq, entries);
		st->fonts[NFONT_BOLD]--;
		if (!bqueue_font(st, obq, 1))
			goto out;
		if (st->flags & LOWDOWN_NROFF_NOLINK) {
			rc = 1;
			goto out;
		}

		/* Optionally output the link following the content. */

		if (bqueue_span(obq, " <") == NULL)
			goto out;
		st->fonts[NFONT_ITALIC]++;
		if (!bqueue_font(st, obq, 0))
			goto out;
		if ((bn = bqueue_span(obq, NULL)) == NULL)
			goto out;
		if (st->flags & LOWDOWN_NROFF_SHORTLINK) {
			bn->nbuf = hbuf2shortlink(link);
			if (bn->nbuf == NULL)
				goto out;
		} else {
 			bn->buf = strndup(link->data, link->size);
			if (bn->buf == NULL)
				goto out;
		}
		st->fonts[NFONT_ITALIC]--;
		if (!bqueue_font(st, obq, 1))
			goto out;
		if (bqueue_span(obq, ">") == NULL)
			goto out;

		rc = 1;
		goto out;
	} else if (st->man) {
		/* 
		 * For man(7) documents, use UR/UE or MT/ME.  According
		 * to the groff documentation, these are supported by
		 * all modern formatters.
		 */
		if ((ob = hbuf_new(32)) == NULL)
			goto out;

		/* This will strip out the "mailto:", if defined. */

		if (!putlinkhref(ob, link, &type))
			goto out;

		/* Either MT or UR depending on if a URL. */

		bn = bqueue_node(obq, BSCOPE_SEMI, type == HALINK_EMAIL ?
			".MT" : ".UR");
		if (bn == NULL)
			goto out;
		if ((bn->nargs = strndup(ob->data, ob->size)) == NULL)
			goto out;

		/* Link text (optional). */

		if (bq != NULL)
			TAILQ_CONCAT(obq, bq, entries);

		/* Close out the link content. */

		bn = bqueue_node(obq, BSCOPE_SEMI_CLOSE,
			type == HALINK_EMAIL ?  ".ME" : ".UE");
		if (bn == NULL)
			goto out;

		rc = 1;
		goto out;
	}

	/* This is an ms document with groff extensions: use pdfhref. */

	if ((ob = hbuf_new(32)) == NULL)
		goto out;

	/* Encode the URL. */

	if (!HBUF_PUTSL(ob, "-D "))
		goto out;

	/*
	 * If this link an e-mail, make sure it doesn't already start
	 * with "mailto:", which can happen when we override te type by
	 * investigating whether the prefix is "mailto:".
	 */

	if (type == HALINK_EMAIL && !hbuf_strprefix(link, "mailto:") &&
	    !HBUF_PUTSL(ob, "mailto:"))
		goto out;
	if (!putlinkhref(ob, link, NULL))
		goto out;
	if (!HBUF_PUTSL(ob, " -- "))
		goto out;

	/*
	 * If no content, ouput the link (possibly stripping "mailto:").
	 * Otherwise, flush the content to the output.
	 */

	if (bq == NULL && !putlinkhref(ob, link, &type))
		goto out;
	else if (bq != NULL && !bqueue_flush(st, ob, bq))
		goto out;

	/*
	 * If we have an ID, emit it before the link part.  This is
	 * important because this isn't printed, so using "-A \c" will
	 * have no effect, so that's used on the subsequent link.
	 */

	if (id != NULL && id->size > 0) {
		bn = bqueue_node(obq, BSCOPE_SEMI, ".pdfhref M");
		if (bn == NULL)
			goto out;
		bn->args = strndup(id->data, id->size);
		if (bn->args == NULL)
			goto out;
	}

	/* Finally, emit the external or in-page link contents. */

	bn = bqueue_node(obq, BSCOPE_SEMI,
		(type != HALINK_EMAIL && link->size > 0 &&
		 link->data[0] == '#') ?
		".pdfhref L" : ".pdfhref W");
	if (bn == NULL)
		goto out;
	if ((bn->nargs = strndup(ob->data, ob->size)) == NULL)
		goto out;

	rc = 1;
out:
	hbuf_free(ob);
	return rc;
}

/*
 * Return FALSE on failure, TRUE on success.
 */
static int
rndr_autolink(struct nroff *st, struct bnodeq *obq,
	const struct lowdown_node *n)
{

	return putlink(obq, st, n, &n->rndr_autolink.link, NULL, NULL,
		n->rndr_autolink.type);
}

static int
rndr_blockcode(struct nroff *st, struct bnodeq *obq,
    const struct rndr_blockcode *param)
{
	struct bnode	*bn;

	/*
	 * XXX: intentionally don't use LD/DE because it introduces
	 * vertical space.  This means that subsequent blocks
	 * (paragraphs, etc.) will have a double-newline.
	 */

	if (bqueue_block(st, obq, ".LP") == NULL)
		return 0;

	if (st->man && (st->flags & LOWDOWN_NROFF_GROFF)) {
		if (bqueue_block(st, obq, ".EX") == NULL)
			return 0;
	} else {
		if (bqueue_block(st, obq, ".nf") == NULL)
			return 0;
		if (bqueue_block(st, obq, ".ft CR") == NULL)
			return 0;
	}

	if ((bn = calloc(1, sizeof(struct bnode))) == NULL)
		return 0;
	TAILQ_INSERT_TAIL(obq, bn, entries);
	bn->scope = BSCOPE_LITERAL;
	bn->buf = strndup(param->text.data, param->text.size);
	if (bn->buf == NULL)
		return 0;

	if (st->man && (st->flags & LOWDOWN_NROFF_GROFF))
		return bqueue_block(st, obq, ".EE") != NULL;

	if (bqueue_block(st, obq, ".ft") == NULL)
		return 0;
	return bqueue_block(st, obq, ".fi") != NULL;
}

static int
rndr_definition_title(struct nroff *st, struct bnodeq *obq,
     struct bnodeq *bq)
{
	char	 buf[32];

	snprintf(buf, sizeof(buf), ".TP %zu", st->indent);

	if (st->man && bqueue_block(st, obq, buf) == NULL)
		return 0;
	else if (!st->man && bqueue_block(st, obq, ".XP") == NULL)
		return 0;
	TAILQ_CONCAT(obq, bq, entries);
	if (st->man && bqueue_span(obq, "\n") == NULL)
		return 0;
	else if (!st->man && bqueue_block(st, obq, ".br") == NULL)
		return 0;
	return 1;
}

static int
rndr_definition_data(const struct nroff *st, struct bnodeq *obq,
    struct bnodeq *bq)
{
	/* Strip out leading paragraphs. */

	bqueue_strip_paras(bq);
	TAILQ_CONCAT(obq, bq, entries);
	return 1;
}

static int
rndr_list(struct nroff *st, struct bnodeq *obq, 
    const struct lowdown_node *n, struct bnodeq *bq)
{
	/* 
	 * If we have a nested list, we need to use RS/RE to indent the
	 * nested component.  Otherwise the "IP" used for the titles and
	 * contained paragraphs won't indent properly.
	 */

	for (n = n->parent; n != NULL; n = n->parent)
		if (n->type == LOWDOWN_LISTITEM)
			break;

	if (n != NULL && bqueue_block(st, obq, ".RS") == NULL)
		return 0;
	TAILQ_CONCAT(obq, bq, entries);
	if (n != NULL && bqueue_block(st, obq, ".RE") == NULL)
		return 0;

	st->post_para = 1;
	return 1;
}

static int
rndr_blockquote(struct nroff *st, struct bnodeq *obq,
    struct bnodeq *bq)
{

	if (bqueue_block(st, obq, ".RS") == NULL)
		return 0;
	TAILQ_CONCAT(obq, bq, entries);
	return bqueue_block(st, obq, ".RE") != NULL;
}

static int
rndr_codespan(struct bnodeq *obq, const struct rndr_codespan *param)
{
	struct bnode	*bn;

	if ((bn = bqueue_span(obq, NULL)) == NULL)
		return 0;
	bn->buf = strndup(param->text.data, param->text.size);
	return bn->buf != NULL;
}

static int
rndr_linebreak(struct nroff *st, struct bnodeq *obq)
{

	return bqueue_block(st, obq, ".br") != NULL;
}

static int
rndr_header(struct nroff *st, struct bnodeq *obq, struct bnodeq *bq,
    const struct lowdown_node *n)
{
	ssize_t				 level;
	struct bnode			*bn;
	struct lowdown_buf		*buf = NULL;
	const struct lowdown_buf	*nbuf;
	int			 	 rc = 0;
        const struct lowdown_node	*child;

	level = (ssize_t)n->rndr_header.level + st->headers_offs;
	if (level < 1)
		level = 1;

	/*
	 * For man(7), we use SH for the first-level section, SS for
	 * other sections.  TODO: use PP then italics or something for
	 * third-level etc.
	 */

	if (st->man) {
		bn = level == 1 ?
			bqueue_block(st, obq, ".SH") :
			bqueue_block(st, obq, ".SS");
		if (bn == NULL)
			return 0;

		/*
		 * Do a scan of the contents of the SH.  If there's only
		 * normal text (or entities), then record this fact.  It
		 * will be used in bqueue_flush() for how the macro is
		 * serialised.
		 */

		if (level == 1) {
			bn->headerhack = 1;
			TAILQ_FOREACH(child, &n->children, entries) {
				if (child->type == LOWDOWN_ENTITY ||
				    child->type == LOWDOWN_NORMAL_TEXT)
					continue;
				bn->headerhack = 0;
				break;
			}
		}

		TAILQ_CONCAT(obq, bq, entries);
		st->post_para = 1;
		return 1;
	} 

	/*
	 * If we're using ms(7) w/groff extensions and w/o numbering,
	 * used the numbered version of the SH macro.
	 * If we're numbered ms(7), use NH.
	 */

	bn = (st->flags & LOWDOWN_NROFF_NUMBERED) ?
		bqueue_block(st, obq, ".NH") :
		bqueue_block(st, obq, ".SH");
	if (bn == NULL)
		goto out;

	if ((st->flags & LOWDOWN_NROFF_NUMBERED) ||
	    (st->flags & LOWDOWN_NROFF_GROFF)) 
		if (asprintf(&bn->nargs, "%zd", level) == -1) {
			bn->nargs = NULL;
			goto out;
		}

	TAILQ_CONCAT(obq, bq, entries);
	st->post_para = 1;

	/*
	 * Used in -mspdf output for creating a TOC and intra-document
	 * linking.
	 */

	if (st->flags & LOWDOWN_NROFF_GROFF) {
		if ((buf = hbuf_new(32)) == NULL)
			goto out;
		if (!hbuf_extract_text(buf, n))
			goto out;

		if ((bn = bqueue_block(st, obq, ".pdfhref")) == NULL)
			goto out;
		if (asprintf(&bn->nargs, "O %zd", level) == -1) {
			bn->nargs = NULL;
			goto out;
		}

		/*
		 * No need to quote: quotes will be converted by
		 * escaping into roff.
		 */

		bn->args = strndup(buf->data, buf->size);
		if (bn->args == NULL)
			goto out;

		if ((bn = bqueue_block(st, obq, ".pdfhref M")) == NULL)
			goto out;

		/*
		 * If the identifier comes from the user, we need to
		 * escape it accordingly; otherwise, use it directly as
		 * the hbuf_id() function will take care of it.
		 */

		if (n->rndr_header.attr_id.size) {
			bn->args = strndup
				(n->rndr_header.attr_id.data,
				 n->rndr_header.attr_id.size);
			if (bn->args == NULL)
				goto out;
		} else {
			nbuf = hbuf_id(buf, NULL, &st->headers_used);
			if (nbuf == NULL)
				goto out;
			bn->nargs = strndup(nbuf->data, nbuf->size);
			if (bn->nargs == NULL)
				goto out;
		}
	}

	rc = 1;
out:
	hbuf_free(buf);
	return rc;
}

/*
 * Return FALSE on failure, TRUE on success.
 */
static ssize_t
rndr_link(struct nroff *st, struct bnodeq *obq, struct bnodeq *bq,
	const struct lowdown_node *n)
{

	return putlink(obq, st, n, &n->rndr_link.link,
		&n->rndr_link.attr_id, bq, HALINK_NORMAL);
}

static int
rndr_listitem(struct nroff *st, struct bnodeq *obq,
    const struct lowdown_node *n, struct bnodeq *bq,
    const struct rndr_listitem *param)
{
	struct bnode	*bn;
	const char	*box;
	size_t		 total = 0, numsize;

	/*
	 * When indenting for the number of bullet preceding the line of
	 * text, use "indent" spaces as the default.  For ordered lists
	 * stretching beyond the indent size, enlarge as necessary.
	 */

	if (param->flags & HLIST_FL_ORDERED) {
		if (n->parent != NULL &&
		    n->parent->type == LOWDOWN_LIST)
			total = n->parent->rndr_list.items +
				(n->parent->rndr_list.start - 1);

		/* Yes, a little ridiculous, but doesn't hurt. */

		numsize = total < 10 ? 3 :
			total < 100 ? 4 :
			total < 1000 ? 5 :
			total < 10000 ? 6 :
			total < 100000 ? 7 :
			total < 1000000 ? 8 :
			total < 10000000 ? 9 :
			10;

		if (numsize < st->indent)
			numsize = st->indent;

		if ((bn = bqueue_block(st, obq, ".IP")) == NULL)
			return 0;
		if (asprintf(&bn->nargs, 
		    "\"%zu.\" %zu", param->num, numsize) == -1)
			return 0;
	} else if (param->flags & HLIST_FL_UNORDERED) {
		if (param->flags & HLIST_FL_CHECKED)
			box = "[u2611]";
		else if (param->flags & HLIST_FL_UNCHECKED)
			box = "[u2610]";
		else
			box = "(bu";
		if ((bn = bqueue_block(st, obq, ".IP")) == NULL)
			return 0;
		if (asprintf(&bn->nargs, "\"\\%s\" %zu",
		    box, st->indent) == -1)
			return 0;
	}

	/* Strip out all leading redundant paragraphs. */

	bqueue_strip_paras(bq);
	TAILQ_CONCAT(obq, bq, entries);

	/* 
	 * Suppress trailing space if we're not in a block and there's a
	 * list item that comes after us (i.e., anything after us).
	 */

	if ((n->rndr_listitem.flags & HLIST_FL_BLOCK) ||
	    (n->rndr_listitem.flags & HLIST_FL_DEF))
		return 1;

	if (TAILQ_NEXT(n, entries) != NULL &&
	    (bqueue_block(st, obq, ".if n \\\n.sp -1") == NULL ||
	     bqueue_block(st, obq, ".if t \\\n.sp -0.25v\n") == NULL))
		return 0;

	return 1;
}

static int
rndr_paragraph(struct nroff *st, const struct lowdown_node *n,
    struct bnodeq *obq, struct bnodeq *nbq)
{
	struct bnode	*bn;

	/* 
	 * Subsequent paragraphs get a PP for the indentation; otherwise, use
	 * LP and forego the indentation.  If we're in a list item, make sure
	 * that we don't reset our text indent by using an "IP".
	 */

	for ( ; n != NULL; n = n->parent)
		if (n->type == LOWDOWN_LISTITEM)
			break;
	if (n != NULL)
		bn = bqueue_block(st, obq, ".IP");
	else if (st->post_para)
		bn = bqueue_block(st, obq, ".LP");
	else
		bn = bqueue_block(st, obq, ".PP");
	if (bn == NULL)
		return 0;

	TAILQ_CONCAT(obq, nbq, entries);
	st->post_para = 0;
	return 1;
}

static int
rndr_raw_block(const struct nroff *st, struct bnodeq *obq,
    const struct rndr_blockhtml *param)
{
	struct bnode	*bn;

	if (st->flags & LOWDOWN_NROFF_SKIP_HTML)
		return 1;
	if ((bn = calloc(1, sizeof(struct bnode))) == NULL)
		return 0;
	TAILQ_INSERT_TAIL(obq, bn, entries);
	bn->scope = BSCOPE_LITERAL;
	bn->buf = strndup(param->text.data, param->text.size);
	return bn->buf != NULL;
}

static int
rndr_hrule(struct nroff *st, struct bnodeq *obq)
{

	/* The LP is to reset the margins. */

	if (bqueue_block(st, obq, ".LP") == NULL)
		return 0;

	/* Set post_para so we get a following LP not PP. */

	st->post_para = 1;

	if (st->man)
		return bqueue_block(st, obq, "\\l\'2i'") != NULL;

	return bqueue_block(st, obq,
	    ".ie d HR \\{\\\n"
	    ".HR\n"
	    "\\}\n"
	    ".el \\{\\\n"
	    ".sp 1v\n"
	    "\\l'\\n(.lu'\n"
	    ".sp 1v\n"
	    ".\\}") != NULL;
}

static int
rndr_image(struct nroff *st, struct bnodeq *obq, 
    const struct rndr_image *param)
{
	const char	*cp;
	size_t		 sz;
	struct bnode	*bn;

	if (!st->man) {
		cp = memrchr(param->link.data, '.', param->link.size);
		if (cp != NULL) {
			cp++;
			sz = param->link.size - (cp - param->link.data);
			if ((sz == 2 && memcmp(cp, "ps", 2) == 0) ||
			    (sz == 3 && memcmp(cp, "eps", 3) == 0)) {
				bn = bqueue_block(st, obq, ".PSPIC");
				if (bn == NULL)
					return 0;
				bn->args = strndup(param->link.data,
					param->link.size);
				return bn->args != NULL;
			}
		}
	}

	/* In -Tman, we have no images: treat as a link. */

	st->fonts[NFONT_BOLD]++;
	if (!bqueue_font(st, obq, 0))
		return 0;
	if ((bn = bqueue_span(obq, NULL)) == NULL)
		return 0;
	bn->buf = strndup(param->alt.data, param->alt.size);
	if (bn->buf == NULL)
		return 0;
	st->fonts[NFONT_BOLD]--;
	if (!bqueue_font(st, obq, 1))
		return 0;
	if (st->flags & LOWDOWN_NROFF_NOLINK)
		return bqueue_span(obq, " (Image)") != NULL;
	if (bqueue_span(obq, " (Image: ") == NULL)
		return 0;
	st->fonts[NFONT_ITALIC]++;
	if (!bqueue_font(st, obq, 0))
		return 0;
	if ((bn = bqueue_span(obq, NULL)) == NULL)
		return 0;
	if (st->flags & LOWDOWN_NROFF_SHORTLINK) {
		bn->nbuf = hbuf2shortlink(&param->link);
		if (bn->nbuf == NULL)
			return 0;
	} else {
		bn->buf = strndup(param->link.data, param->link.size);
		if (bn->buf == NULL)
			return 0;
	}
	st->fonts[NFONT_ITALIC]--;
	if (!bqueue_font(st, obq, 1))
		return 0;
	return bqueue_span(obq, ")") != NULL;
}

static int
rndr_raw_html(const struct nroff *st,
	struct bnodeq *obq, const struct rndr_raw_html *param)
{
	struct bnode	*bn;

	if (st->flags & LOWDOWN_NROFF_SKIP_HTML)
		return 1;
	if ((bn = calloc(1, sizeof(struct bnode))) == NULL)
		return 0;
	TAILQ_INSERT_TAIL(obq, bn, entries);
	bn->scope = BSCOPE_LITERAL;
	bn->buf = strndup(param->text.data, param->text.size);
	return bn->buf != NULL;
}

static int
rndr_table(struct nroff *st, struct bnodeq *obq, struct bnodeq *bq)
{
	const char	*macro;

	macro = st->man || !(st->flags & LOWDOWN_NROFF_GROFF) ?
		".TS" : ".TS H";
	if (bqueue_block(st, obq, macro) == NULL)
		return 0;
	if (bqueue_block(st, obq, "tab(|) expand allbox;") == NULL)
		return 0;
	TAILQ_CONCAT(obq, bq, entries);
	return bqueue_block(st, obq, ".TE") != NULL;
}

static int
rndr_table_header(struct nroff *st, struct bnodeq *obq,
    struct bnodeq *bq, const struct rndr_table_header *param)
{
	size_t		 	 i;
	struct lowdown_buf	*ob;
	struct bnode		*bn;
	int			 rc = 0;

	if ((ob = hbuf_new(32)) == NULL)
		return 0;

	/* 
	 * This specifies the header layout.
	 * We make the header bold, but this is arbitrary.
	 */

	if ((bn = bqueue_block(st, obq, NULL)) == NULL)
		goto out;
	for (i = 0; i < param->columns; i++) {
		if (i > 0 && !HBUF_PUTSL(ob, " "))
			goto out;
		switch (param->flags[i] & HTBL_FL_ALIGNMASK) {
		case HTBL_FL_ALIGN_CENTER:
			if (!HBUF_PUTSL(ob, "cb"))
				goto out;
			break;
		case HTBL_FL_ALIGN_RIGHT:
			if (!HBUF_PUTSL(ob, "rb"))
				goto out;
			break;
		default:
			if (!HBUF_PUTSL(ob, "lb"))
				goto out;
			break;
		}
	}
	if ((bn->nbuf = strndup(ob->data, ob->size)) == NULL)
		goto out;

	/* Now the body layout. */

	hbuf_truncate(ob);
	if ((bn = bqueue_block(st, obq, NULL)) == NULL)
		goto out;
	for (i = 0; i < param->columns; i++) {
		if (i > 0 && !HBUF_PUTSL(ob, " "))
			goto out;
		switch (param->flags[i] & HTBL_FL_ALIGNMASK) {
		case HTBL_FL_ALIGN_CENTER:
			if (!HBUF_PUTSL(ob, "c"))
				goto out;
			break;
		case HTBL_FL_ALIGN_RIGHT:
			if (!HBUF_PUTSL(ob, "r"))
				goto out;
			break;
		default:
			if (!HBUF_PUTSL(ob, "l"))
				goto out;
			break;
		}
	}
	if (!hbuf_putc(ob, '.'))
		goto out;
	if ((bn->nbuf = strndup(ob->data, ob->size)) == NULL)
		goto out;

	TAILQ_CONCAT(obq, bq, entries);

	if (!st->man && (st->flags & LOWDOWN_NROFF_GROFF) &&
	    bqueue_block(st, obq, ".TH") == NULL)
		goto out;

	rc = 1;
out:
	hbuf_free(ob);
	return rc;
}

static int
rndr_table_row(struct nroff *st, struct bnodeq *obq, struct bnodeq *bq)
{

	TAILQ_CONCAT(obq, bq, entries);
	return bqueue_block(st, obq, NULL) != NULL;
}

static int
rndr_table_cell(struct bnodeq *obq, struct bnodeq *bq,
    const struct rndr_table_cell *param)
{
	struct bnode	*bn;

	if (param->col > 0 && bqueue_span(obq, "|") == NULL)
		return 0;
	if (bqueue_span(obq, "T{\n") == NULL)
		return 0;
	TAILQ_CONCAT(obq, bq, entries);
	if ((bn = bqueue_span(obq, "T}")) == NULL)
		return 0;
	bn->tblhack = 1;
	return 1;
}

static int
rndr_superscript(struct bnodeq *obq, struct bnodeq *bq,
    enum lowdown_rndrt type)
{
	const char	*p1, *p2;

	/* Lift pandoc's way of doing this. */

	p1 = (type == LOWDOWN_SUPERSCRIPT) ?
		"\\v\'-0.3m\'\\s[\\n[.s]*9u/12u]" : 
		"\\v\'0.3m\'\\s[\\n[.s]*9u/12u]";
	p2 = (type == LOWDOWN_SUPERSCRIPT) ?
		"\\s0\\v\'0.3m\'" :
		"\\s0\\v\'-0.3m\'";
	if (bqueue_span(obq, p1) == NULL)
		return 0;
	TAILQ_CONCAT(obq, bq, entries);
	return bqueue_span(obq, p2) != NULL;
}

static int
rndr_footnote_def(struct nroff *st, struct bnodeq *obq,
    struct bnodeq *bq, size_t num)
{
	struct bnode	*bn;

	/* 
	 * Use groff_ms(7)-style footnotes.
	 * We know that the definitions are delivered in the same order
	 * as the footnotes are made, so we can use the automatic
	 * ordering facilities.
	 */

	if (!st->man) {
		if (bqueue_block(st, obq, ".FS") == NULL)
			return 0;
		bn = bqueue_block(st, obq, ".pdfhref M");
		if (bn == NULL)
			return 0;
		if (asprintf(&bn->args, "footnote-%zu", num) == -1)
			return 0;
		bqueue_strip_paras(bq);
		TAILQ_CONCAT(obq, bq, entries);
		return bqueue_block(st, obq, ".FE") != NULL;
	}

	/*
	 * For man(7), just print as normal, with a leading footnote
	 * number in italics and superscripted.
	 */

	if (bqueue_block(st, obq, ".LP") == NULL)
		return 0;
	if ((bn = bqueue_span(obq, NULL)) == NULL)
		return 0;
	if (asprintf(&bn->nbuf, 
	    "\\0\\fI\\u\\s-3%zu\\s+3\\d\\fP\\0", num) == -1) {
		bn->nbuf = NULL;
		return 0;
	}
	bqueue_strip_paras(bq);
	TAILQ_CONCAT(obq, bq, entries);
	return 1;
}

/*
 * Flush out footnotes or (in some conditions) do nothing and return
 * success.  If "fin" is non-zero, this is the final invocation of
 * rndr_footnotes() at the root of the document after everything else;
 * otherwise, this is being called within the document.  Footnote
 * conditions are that footnotes must exist, mustn't already be printing
 * and parsing, and satisfy endnote/footnote criterion.  Returns zero on
 * failure (memory allocation), non-zero on success.
 */
static int
rndr_footnotes(struct nroff *st, struct bnodeq *obq, int fin)
{
	/* Already printing/parsing, or none to print. */

	if (st->footdepth > 0 || st->footpos >= st->footsz)
		return 1;

	/* Non-final and in -tman (-tman has only endnotes). */

	if (!fin && st->man)
		return 1;

	/* Non-final and -tms with endnotes specified. */

	if (!fin && !st->man && (st->flags & LOWDOWN_NROFF_ENDNOTES))
		return 1;

	st->footdepth++;
	if (st->man) {
		if (bqueue_block(st, obq, ".LP") == NULL)
			return 0;
		if (bqueue_block(st, obq, ".sp 3") == NULL)
			return 0;
		if (bqueue_block(st, obq, "\\l\'2i'") == NULL)
			return 0;
	}

	for ( ; st->footpos < st->footsz; st->footpos++)
		if (!rndr_footnote_def(st, obq, st->foots[st->footpos],
		    st->footpos + 1))
			return 0;

	assert(st->footdepth > 0);
	st->footdepth--;
	return 1;
}

static int
rndr_footnote_ref(struct nroff *st, struct bnodeq *obq,
	struct bnodeq *bq)
{
	struct bnode	*bn;
	void		*pp;
	size_t		 num = st->footsz + 1;

	/* 
	 * Use groff_ms(7)-style automatic footnoting, else just put a
	 * reference number in small superscripts.
	 */

	if (st->man) {
		if ((bn = bqueue_span(obq, NULL)) == NULL)
			return 0;
		if (asprintf(&bn->nbuf, "\\u\\s-3%zu\\s+3\\d",
		    num) == -1)
			bn->nbuf = NULL;
		if (bn->nbuf == NULL)
			return 0;
	} else {
		bn = bqueue_node(obq, BSCOPE_SEMI, ".pdfhref L");
		if (bn == NULL)
			return 0;
		if (asprintf(&bn->nargs, "-D footnote-%zu -- \\**",
		    num) == -1)
			bn->nargs = NULL;
		if (bn->nargs == NULL)
			return 0;
	}

	/*
	 * Queue the footnote for printing at the end of the document.
	 * The FS/FE could be printed now, but it's easier for the block
	 * printing algorithm to determine that the link shouldn't have
	 * trailing space without it.
	 */

	pp = recallocarray(st->foots, st->footsz,
		st->footsz + 1, sizeof(struct bnodeq *));
	if (pp == NULL)
		return 0;
	st->foots = pp;
	st->foots[st->footsz] = malloc(sizeof(struct bnodeq));
	if (st->foots[st->footsz] == NULL)
		return 0;
	TAILQ_INIT(st->foots[st->footsz]);
	TAILQ_CONCAT(st->foots[st->footsz], bq, entries);
	st->footsz++;
	return 1;
}

static int
rndr_entity(const struct nroff *st,
	struct bnodeq *obq, const struct rndr_entity *param)
{
	char		 buf[32];
	const char	*ent;
	struct bnode	*bn;
	int32_t		 iso;
	size_t		 sz;

	/*
	 * Handle named entities if "ent" is non-NULL, use unicode
	 * escapes for values above 126, and just the regular character
	 * if within the ASCII set.
	 */

	if ((ent = entity_find_nroff(&param->text, &iso)) != NULL) {
		sz = strlen(ent);
		if (sz == 1)
			snprintf(buf, sizeof(buf), "\\%s", ent);
		else if (sz == 2)
			snprintf(buf, sizeof(buf), "\\(%s", ent);
		else
			snprintf(buf, sizeof(buf), "\\[%s]", ent);
		return bqueue_span(obq, buf) != NULL;
	} else if (iso > 0 && iso > 126) {
		if (st->flags & LOWDOWN_NROFF_GROFF)
			snprintf(buf, sizeof(buf), "\\[u%.4llX]", 
				(unsigned long long)iso);
		else
			snprintf(buf, sizeof(buf), "\\U\'%.4llX\'", 
				(unsigned long long)iso);
		return bqueue_span(obq, buf) != NULL;
	} else if (iso > 0) {
		snprintf(buf, sizeof(buf), "%c", iso);
		return bqueue_span(obq, buf) != NULL;
	}

	if ((bn = bqueue_span(obq, NULL)) == NULL)
		return 0;
	bn->buf = strndup(param->text.data, param->text.size);
	return bn->buf != NULL;
}

/*
 * Split "b" at sequential white-space, outputting the results per-line,
 * after outputting the initial block macro.
 * The content in "b" has not been escaped.
 */
static int
rndr_meta_multi(struct nroff *st, struct bnodeq *obq, const char *b,
    const char *env)
{
	const char	*start;
	size_t		 sz, i, bsz;
	struct bnode	*bn;

	if (b == NULL)
		return 1;

	bsz = strlen(b);

	if (bqueue_block(st, obq, env) == NULL)
		return 0;

	for (i = 0; i < bsz; i++) {
		while (i < bsz &&
		       isspace((unsigned char)b[i]))
			i++;
		if (i == bsz)
			continue;
		start = &b[i];

		for (; i < bsz; i++)
			if (i < bsz - 1 &&
			    isspace((unsigned char)b[i]) &&
			    isspace((unsigned char)b[i + 1]))
				break;
		if ((sz = &b[i] - start) == 0)
			continue;

		if ((bn = bqueue_block(st, obq, NULL)) == NULL)
			return 0;
		if ((bn->buf = strndup(start, sz)) == NULL)
			return 0;
	}

	return 1;
}

/*
 * Fill "mq" by serialising child nodes into strings.  The serialised
 * strings are escaped.
 */
static int
rndr_meta(struct nroff *st, const struct lowdown_node *n,
    struct lowdown_metaq *mq)
{
	struct lowdown_meta	*m;
	ssize_t			 val;
	const char		*ep;

	if ((m = lowdown_get_meta(n, mq)) == NULL)
		return 0;

	if (strcmp(m->key, "shiftheadinglevelby") == 0) {
		val = (ssize_t)strtonum(m->value, -100, 100, &ep);
		if (ep == NULL)
			st->headers_offs = val + 1;
	} else if (strcmp(m->key, "baseheaderlevel") == 0) {
		val = (ssize_t)strtonum(m->value, 1, 100, &ep);
		if (ep == NULL)
			st->headers_offs = val;
	}

	return 1;
}

static int
rndr_doc_header(struct nroff *st, struct bnodeq *obq,
    const struct lowdown_metaq *mq)
{
	struct lowdown_buf		*ob = NULL;
	struct bnode			*bn;
	const struct lowdown_meta	*m;
	int				 rc = 0;
	const char			*author = NULL, *title = NULL,
					*affil = NULL, *date = NULL,
					*copy = NULL, *sec = NULL,
					*rcsauthor = NULL, *rcsdate = NULL,
					*source = NULL, *volume = NULL,
					*msheader = NULL,
					*manheader = NULL;

	if (!(st->flags & LOWDOWN_STANDALONE))
		return 1;

	TAILQ_FOREACH(m, mq, entries)
		if (strcasecmp(m->key, "author") == 0)
			author = m->value;
		else if (strcasecmp(m->key, "copyright") == 0)
			copy = m->value;
		else if (strcasecmp(m->key, "affiliation") == 0)
			affil = m->value;
		else if (strcasecmp(m->key, "date") == 0)
			date = m->value;
		else if (strcasecmp(m->key, "rcsauthor") == 0)
			rcsauthor = rcsauthor2str(m->value);
		else if (strcasecmp(m->key, "rcsdate") == 0)
			rcsdate = rcsdate2str(m->value);
		else if (strcasecmp(m->key, "title") == 0)
			title = m->value;
		else if (strcasecmp(m->key, "section") == 0)
			sec = m->value;
		else if (strcasecmp(m->key, "source") == 0)
			source = m->value;
		else if (strcasecmp(m->key, "volume") == 0)
			volume = m->value;
		else if (strcasecmp(m->key, "msheader") == 0)
			msheader = m->value;
		else if (strcasecmp(m->key, "manheader") == 0)
			manheader = m->value;

	/* Overrides. */

	if (sec == NULL)
		sec = "7";
	if (rcsdate != NULL)
		date = rcsdate;
	if (rcsauthor != NULL)
		author = rcsauthor;

	bn = bqueue_block(st, obq, 
		".\\\" -*- mode: troff; coding: utf-8 -*-");
	if (bn == NULL)
		goto out;

	if (!st->man) {
		if (copy != NULL) {
			bn = bqueue_block(st, obq,
				".ds LF Copyright \\(co");
			if (bn == NULL)
				goto out;
			if ((bn->args = strdup(copy)) == NULL)
				goto out;
		}
		if (date != NULL) {
			if (copy != NULL)
				bn = bqueue_block(st, obq, ".ds RF");
			else
				bn = bqueue_block(st, obq, ".DA");
			if (bn == NULL)
				goto out;
			if ((bn->args = strdup(date)) == NULL)
				goto out;
		}

		if (msheader != NULL &&
		    bqueue_block(st, obq, msheader) == NULL)
			goto out;

		/*
		 * The title is required if having an author or
		 * affiliation; however, it doesn't make a difference if
		 * there are none of these elements, so specify it
		 * anyway.
		 */

		if (bqueue_block(st, obq, ".TL") == NULL)
			goto out;
		if (title != NULL) {
			if ((bn = bqueue_span(obq, NULL)) == NULL)
				goto out;
			if ((bn->buf = strdup(title)) == NULL)
				goto out;
		}
		
		/*
		 * XXX: in groff_ms(7), it's stipulated that multiple
		 * authors get multiple AU invocations.  However, these
		 * are grouped with the subsequent AI.  In lowdown, we
		 * accept all authors and institutions at once (without
		 * grouping), so simply put these all together.
		 */

		if (!rndr_meta_multi(st, obq, author, ".AU"))
			goto out;
		if (!rndr_meta_multi(st, obq, affil, ".AI"))
			goto out;
	} else {
		if (manheader != NULL &&
		    bqueue_block(st, obq, manheader) == NULL)
			goto out;

		if ((ob = hbuf_new(32)) == NULL)
			goto out;

		/*
		 * The syntax of this macro, according to man(7), is 
		 * TH name section date [source [volume]].
		 */

		if ((bn = bqueue_block(st, obq, ".TH")) == NULL)
			goto out;
		if (!HBUF_PUTSL(ob, "\""))
			goto out;
		if (title != NULL &&
		    !hesc_nroff(ob, title, strlen(title), 1, 0, 1))
			goto out;
		if (!HBUF_PUTSL(ob, "\" \""))
			goto out;
		if (!hesc_nroff(ob, sec, strlen(sec), 1, 0, 1))
			goto out;
		if (!HBUF_PUTSL(ob, "\" \""))
			goto out;

		/*
		 * We may not have a date (or it may be empty), in which
		 * case man(7) says the current date is used.
		 */

		if (date != NULL &&
		    !hesc_nroff(ob, date, strlen(date), 1, 0, 1))
			goto out;
		if (!HBUF_PUTSL(ob, "\""))
			goto out;

		/*
		 * Don't print these unless necessary, as the latter
		 * overrides the default system printing for the
		 * section.
		 */

		if (source != NULL || volume != NULL) {
			if (!HBUF_PUTSL(ob, " \""))
				goto out;
			if (source != NULL && !hesc_nroff
			    (ob, source, strlen(source), 1, 0, 1))
				goto out;
			if (!HBUF_PUTSL(ob, "\""))
				goto out;
			if (!HBUF_PUTSL(ob, " \""))
				goto out;
			if (volume != NULL && !hesc_nroff
			    (ob, volume, strlen(volume), 1, 0, 1))
				goto out;
			if (!HBUF_PUTSL(ob, "\""))
				goto out;
		}
		if ((bn->nargs = strndup(ob->data, ob->size)) == NULL)
			goto out;
	}

	rc = 1;
out:
	hbuf_free(ob);
	return rc;
}

/*
 * Actually render the node "n" and all of its children into the output
 * buffer "ob", chopping "chop" from the current node if specified.
 * Return what (if anything) we should chop from the next node or <0 on
 * failure.
 */
static int
rndr(struct lowdown_metaq *mq, struct nroff *st,
	const struct lowdown_node *n, struct bnodeq *obq)
{
	const struct lowdown_node	*child;
	int				 rc = 1, post_para = st->post_para;
	enum nfont			 fonts[NFONT__MAX];
	struct bnodeq			 tmpbq;
	struct bnode			*bn;

	TAILQ_INIT(&tmpbq);

	if ((n->chng == LOWDOWN_CHNG_INSERT ||
	     n->chng == LOWDOWN_CHNG_DELETE) &&
	    !bqueue_colour(obq, n->chng, 0))
		goto out;

	/*
	 * Font management.
	 * roff doesn't handle its own font stack, so we can't set fonts
	 * and step out of them in a nested way.
	 */

	memcpy(fonts, st->fonts, sizeof(fonts));

	switch (n->type) {
	case LOWDOWN_CODESPAN:
		st->fonts[NFONT_FIXED]++;
		if (!bqueue_font(st, obq, 0))
			goto out;
		break;
	case LOWDOWN_EMPHASIS:
		st->fonts[NFONT_ITALIC]++;
		if (!bqueue_font(st, obq, 0))
			goto out;
		break;
	case LOWDOWN_HIGHLIGHT:
	case LOWDOWN_DOUBLE_EMPHASIS:
		st->fonts[NFONT_BOLD]++;
		if (!bqueue_font(st, obq, 0))
			goto out;
		break;
	case LOWDOWN_TRIPLE_EMPHASIS:
		st->fonts[NFONT_ITALIC]++;
		st->fonts[NFONT_BOLD]++;
		if (!bqueue_font(st, obq, 0))
			goto out;
		break;
	default:
		break;
	}

	/* Guard against flushing footnotes. */

	if (n->type == LOWDOWN_FOOTNOTE)
		st->footdepth++;

	TAILQ_FOREACH(child, &n->children, entries)
		if (!rndr(mq, st, child, &tmpbq))
			goto out;

	switch (n->type) {
	case LOWDOWN_BLOCKCODE:
		rc = rndr_blockcode(st, obq, &n->rndr_blockcode);
		break;
	case LOWDOWN_BLOCKQUOTE:
		rc = rndr_blockquote(st, obq, &tmpbq);
		break;
	case LOWDOWN_DEFINITION:
		rc = rndr_list(st, obq, n, &tmpbq);
		break;
	case LOWDOWN_DEFINITION_DATA:
		rc = rndr_definition_data(st, obq, &tmpbq);
		break;
	case LOWDOWN_DEFINITION_TITLE:
		rc = rndr_definition_title(st, obq, &tmpbq);
		break;
	case LOWDOWN_DOC_HEADER:
		rc = rndr_doc_header(st, obq, mq);
		break;
	case LOWDOWN_META:
		if (n->chng != LOWDOWN_CHNG_DELETE)
			rc = rndr_meta(st, n, mq);
		break;
	case LOWDOWN_HEADER:
		rc = rndr_header(st, obq, &tmpbq, n);
		break;
	case LOWDOWN_HRULE:
		rc = rndr_hrule(st, obq);
		break;
	case LOWDOWN_LIST:
		rc = rndr_list(st, obq, n, &tmpbq);
		break;
	case LOWDOWN_LISTITEM:
		rc = rndr_listitem(st,
			obq, n, &tmpbq, &n->rndr_listitem);
		break;
	case LOWDOWN_PARAGRAPH:
		rc = rndr_paragraph(st, n, obq, &tmpbq);
		break;
	case LOWDOWN_TABLE_BLOCK:
		rc = rndr_table(st, obq, &tmpbq);
		break;
	case LOWDOWN_TABLE_HEADER:
		rc = rndr_table_header(st, 
			obq, &tmpbq, &n->rndr_table_header);
		break;
	case LOWDOWN_TABLE_ROW:
		rc = rndr_table_row(st, obq, &tmpbq);
		break;
	case LOWDOWN_TABLE_CELL:
		rc = rndr_table_cell(obq, &tmpbq, &n->rndr_table_cell);
		break;
	case LOWDOWN_ROOT:
		TAILQ_CONCAT(obq, &tmpbq, entries);
		assert(st->footdepth == 0);
		rc = rndr_footnotes(st, obq, 1);
		break;
	case LOWDOWN_BLOCKHTML:
		rc = rndr_raw_block(st, obq, &n->rndr_blockhtml);
		break;
	case LOWDOWN_LINK_AUTO:
		rc = rndr_autolink(st, obq, n);
		break;
	case LOWDOWN_CODESPAN:
		rc = rndr_codespan(obq, &n->rndr_codespan);
		break;
	case LOWDOWN_IMAGE:
		rc = rndr_image(st, obq, &n->rndr_image);
		break;
	case LOWDOWN_LINEBREAK:
		rc = rndr_linebreak(st, obq);
		break;
	case LOWDOWN_LINK:
		rc = rndr_link(st, obq, &tmpbq, n);
		break;
	case LOWDOWN_SUBSCRIPT:
		rc = rndr_superscript(obq, &tmpbq, n->type);
		break;
	case LOWDOWN_SUPERSCRIPT:
		rc = rndr_superscript(obq, &tmpbq, n->type);
		break;
	case LOWDOWN_FOOTNOTE:
		rc = rndr_footnote_ref(st, obq, &tmpbq);
		assert(st->footdepth > 0);
		st->footdepth--;
		/*
		 * Restore what subsequent paragraphs should do.  This
		 * macro will create output that's delayed in being
		 * shown.  It might set post_para, which we don't want
		 * to propagate to the actual output that will follow.
		 */
		st->post_para = post_para;
		break;
	case LOWDOWN_RAW_HTML:
		rc = rndr_raw_html(st, obq, &n->rndr_raw_html);
		break;
	case LOWDOWN_NORMAL_TEXT:
		if ((bn = bqueue_span(obq, NULL)) == NULL)
			goto out;
		bn->buf = strndup
			(n->rndr_normal_text.text.data,
			 n->rndr_normal_text.text.size);
		if (bn->buf == NULL)
			goto out;
		break;
	case LOWDOWN_ENTITY:
		rc = rndr_entity(st, obq, &n->rndr_entity);
		break;
	default:
		TAILQ_CONCAT(obq, &tmpbq, entries);
		break;
	}

	if (rc == 0)
		goto out;

	/* Restore the font stack. */

	switch (n->type) {
	case LOWDOWN_CODESPAN:
	case LOWDOWN_EMPHASIS:
	case LOWDOWN_HIGHLIGHT:
	case LOWDOWN_DOUBLE_EMPHASIS:
	case LOWDOWN_TRIPLE_EMPHASIS:
		memcpy(st->fonts, fonts, sizeof(fonts));
		if (!bqueue_font(st, obq, 1)) {
			rc = 0;
			goto out;
		}
		break;
	default:
		break;
	}

	if ((n->chng == LOWDOWN_CHNG_INSERT ||
	     n->chng == LOWDOWN_CHNG_DELETE) &&
	    !bqueue_colour(obq, n->chng, 1)) {
		rc = 0;
		goto out;
	}

	/*
	 * Flush out all existing footnotes, if applicable.  This is
	 * because in -tms with footnotes, footnotes will go on the same
	 * page as the footnote definition, but only if the FS/FE is
	 * declared on the same page as well.  This is delayed until a
	 * block because, if it were produced alongside the .pdfhref
	 * macro, it would confuse spacing in the event, of, e.g.,
	 * foo[^ref]bar.
	 */
	
	switch (n->type) {
	case LOWDOWN_BLOCKCODE:
	case LOWDOWN_BLOCKQUOTE:
	case LOWDOWN_PARAGRAPH:
	case LOWDOWN_DEFINITION:
	case LOWDOWN_LIST:
	case LOWDOWN_HEADER:
	case LOWDOWN_TABLE_BLOCK:
		if (!rndr_footnotes(st, obq, 0)) {
			rc = 0;
			goto out;
		}
		break;
	default:
		break;
	}
out:
	bqueue_free(&tmpbq);
	return rc;
}

int
lowdown_nroff_rndr(struct lowdown_buf *ob,
	void *arg, const struct lowdown_node *n)
{
	struct nroff		*st = arg;
	struct lowdown_metaq	 metaq;
	int			 rc = 0;
	struct bnodeq		 bq;
	size_t			 i;

	TAILQ_INIT(&metaq);
	TAILQ_INIT(&bq);
	TAILQ_INIT(&st->headers_used);

	memset(st->fonts, 0, sizeof(st->fonts));
	st->headers_offs = 1;
	st->post_para = 0;

	if (rndr(&metaq, st, n, &bq)) {
		if (!bqueue_flush(st, ob, &bq))
			goto out;
		if (ob->size && ob->data[ob->size - 1] != '\n' &&
		    !hbuf_putc(ob, '\n'))
			goto out;
		rc = 1;
	}

out:
	for (i = 0; i < st->footsz; i++) {
		bqueue_free(st->foots[i]);
		free(st->foots[i]);
	}

	free(st->foots);
	st->footsz = st->footpos = 0;
	st->foots = NULL;
	lowdown_metaq_free(&metaq);
	bqueue_free(&bq);
	hentryq_clear(&st->headers_used);
	return rc;
}

void *
lowdown_nroff_new(const struct lowdown_opts *opts)
{
	struct nroff 	*p;

	if ((p = calloc(1, sizeof(struct nroff))) == NULL)
		return NULL;

	p->flags = opts != NULL ? opts->oflags : 0;
	p->man = opts != NULL && opts->type == LOWDOWN_MAN;
	p->cr = opts != NULL ? opts->nroff.cr : NULL;
	p->cb = opts != NULL ? opts->nroff.cb : NULL;
	p->ci = opts != NULL ? opts->nroff.ci : NULL;
	p->cbi = opts != NULL ? opts->nroff.cbi : NULL;

	/*
	 * Set the default "constant width" fonts.  This is complicated
	 * because the "C" fixed-with font is not universally available
	 * on all output media.  For example, -Tascii does not carry a
	 * "C" font.  However, this is a good enough default.
	 */

	if (p->cr == NULL)
		p->cr = "CR";
	if (p->cb == NULL)
		p->cb = "CB";
	if (p->ci == NULL)
		p->ci = "CI";
	if (p->cbi == NULL)
		p->cbi = "CBI";

	/*
	 * Set a default indentation.  For -man, we use 3 because we
	 * want to be efficient with page width.  For -ms, use 5 because
	 * that'll usually be used for PDF with a variable-width font.
	 */

	p->indent = p->man ? 3 : 5;
	return p;
}

void
lowdown_nroff_free(void *arg)
{

	/* No need to check NULL: pass directly to free(). */

	free(arg);
}
