/*	$NetBSD: pr_comment.c,v 1.154 2023/06/06 07:14:20 rillig Exp $	*/

/*-
 * SPDX-License-Identifier: BSD-4-Clause
 *
 * Copyright (c) 1985 Sun Microsystems, Inc.
 * Copyright (c) 1980, 1993
 *	The Regents of the University of California.  All rights reserved.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/cdefs.h>
__RCSID("$NetBSD: pr_comment.c,v 1.154 2023/06/06 07:14:20 rillig Exp $");

#include <string.h>

#include "indent.h"

static void
com_add_char(char ch)
{
	buf_add_char(&com, ch);
}

static void
com_add_delim(void)
{
	if (opt.star_comment_cont)
		buf_add_chars(&com, " * ", 3);
}

static bool
fits_in_one_line(int com_ind, int max_line_length)
{
	for (const char *start = inp_p, *p = start; *p != '\n'; p++) {
		if (p[0] == '*' && p[1] == '/') {
			int len = ind_add(com_ind + 3,
			    start, (size_t)(p - start));
			len += p == start || ch_isblank(p[-1]) ? 2 : 3;
			return len <= max_line_length;
		}
	}
	return false;
}

static void
analyze_comment(bool *p_may_wrap, bool *p_delim,
    int *p_ind, int *p_line_length)
{
	bool may_wrap = true;
	bool delim = opt.comment_delimiter_on_blankline;
	int ind;
	int line_length = opt.max_line_length;

	if (ps.curr_col_1 && !opt.format_col1_comments) {
		may_wrap = false;
		delim = false;
		ind = 0;

	} else {
		if (inp_p[0] == '-' || inp_p[0] == '*' ||
		    token.s[token.len - 1] == '/' ||
		    (inp_p[0] == '\n' && !opt.format_block_comments)) {
			may_wrap = false;
			delim = false;
		}
		if (code.len == 0 && inp_p[strspn(inp_p, "*")] == '\n')
			out.line_kind = lk_block_comment;

		if (com.len > 0)
			output_line();
		if (lab.len == 0 && code.len == 0) {
			ind = (ps.ind_level - opt.unindent_displace)
			    * opt.indent_size;
			if (ind <= 0)
				ind = opt.format_col1_comments ? 0 : 1;
			line_length = opt.block_comment_max_line_length;
		} else {
			delim = false;

			int target_ind = code.len > 0
			    ? ind_add(compute_code_indent(), code.s, code.len)
			    : ind_add(compute_label_indent(), lab.s, lab.len);

			ind = ps.decl_on_line || ps.ind_level == 0
			    ? opt.decl_comment_column - 1
			    : opt.comment_column - 1;
			if (ind <= target_ind)
				ind = next_tab(target_ind);
			if (ind + 25 > line_length)
				line_length = ind + 25;
		}
	}

	ps.com_ind = ind;

	if (!may_wrap) {
		/* Find out how much indentation there was originally, because
		 * that much will have to be ignored by output_line. */
		size_t len = (size_t)(inp_p - 2 - inp.s);
		ps.n_comment_delta = -ind_add(0, inp.s, len);
	} else {
		ps.n_comment_delta = 0;
		if (!(inp_p[0] == '\t' && !ch_isblank(inp_p[1])))
			while (ch_isblank(inp_p[0]))
				inp_p++;
	}

	*p_may_wrap = may_wrap;
	*p_delim = delim;
	*p_ind = ind;
	*p_line_length = line_length;
}

static void
copy_comment_start(bool may_wrap, bool *delim, int ind, int line_length)
{
	ps.comment_delta = 0;
	com_add_char('/');
	com_add_char(token.s[token.len - 1]);	/* either '*' or '/' */

	if (may_wrap && !ch_isblank(inp_p[0]))
		com_add_char(' ');

	if (*delim && fits_in_one_line(ind, line_length))
		*delim = false;

	if (*delim) {
		output_line();
		com_add_delim();
	}
}

static void
copy_comment_wrap_text(int line_length, ssize_t *last_blank)
{
	int now_len = ind_add(ps.com_ind, com.s, com.len);
	for (;;) {
		char ch = inp_next();
		if (ch_isblank(ch))
			*last_blank = (ssize_t)com.len;
		com_add_char(ch);
		now_len++;
		if (memchr("*\n\r\b\t", inp_p[0], 6) != NULL)
			break;
		if (now_len >= line_length && *last_blank != -1)
			break;
	}

	ps.next_col_1 = false;

	if (now_len <= line_length)
		return;
	if (ch_isspace(com.s[com.len - 1]))
		return;

	if (*last_blank == -1) {
		/* only a single word in this line */
		output_line();
		com_add_delim();
		return;
	}

	const char *last_word_s = com.s + *last_blank + 1;
	size_t last_word_len = com.len - (size_t)(*last_blank + 1);
	com.len = (size_t)*last_blank;
	output_line();
	com_add_delim();

	/* Assume that output_line and com_add_delim don't
	 * invalidate the "unused" part of the buffer beyond
	 * com.s + com.len. */
	memmove(com.s + com.len, last_word_s, last_word_len);
	com.len += last_word_len;
	*last_blank = -1;
}

static bool
copy_comment_wrap_newline(ssize_t *last_blank)
{
	*last_blank = -1;
	if (ps.next_col_1) {
		if (com.len == 0)
			com_add_char(' ');	/* force empty output line */
		if (com.len > 3) {
			output_line();
			com_add_delim();
		}
		output_line();
		com_add_delim();
	} else {
		ps.next_col_1 = true;
		if (!(com.len > 0 && ch_isblank(com.s[com.len - 1])))
			com_add_char(' ');
		*last_blank = (int)com.len - 1;
	}
	++line_no;

	/* flush any blanks and/or tabs at start of next line */
	inp_skip();		/* '\n' */
	while (ch_isblank(inp_p[0]))
		inp_p++;
	if (inp_p[0] == '*' && inp_p[1] == '/')
		return false;
	if (inp_p[0] == '*') {
		inp_p++;
		while (ch_isblank(inp_p[0]))
			inp_p++;
	}

	return true;
}

static void
copy_comment_wrap_finish(int line_length, bool delim)
{
	if (delim) {
		if (com.len > 3)
			output_line();
		else
			com.len = 0;
		com_add_char(' ');
	} else {
		size_t len = com.len;
		while (ch_isblank(com.s[len - 1]))
			len--;
		int end_ind = ind_add(ps.com_ind, com.s, len);
		if (end_ind + 3 > line_length)
			output_line();
	}

	inp_p += 2;
	if (com.len > 0 && ch_isblank(com.s[com.len - 1]))
		buf_add_chars(&com, "*/", 2);
	else
		buf_add_chars(&com, " */", 3);
}

/*
 * Copy characters from 'inp' to 'com'. Try to keep comments from going over
 * the maximum line length. To do that, remember where the last blank, tab, or
 * newline was. When a line is filled, print up to the last blank and continue
 * copying.
 */
static void
copy_comment_wrap(int line_length, bool delim)
{
	ssize_t last_blank = -1;	/* index of the last blank in 'com' */

	for (;;) {
		if (inp_p[0] == '\n') {
			if (had_eof)
				goto unterminated_comment;
			if (!copy_comment_wrap_newline(&last_blank))
				goto end_of_comment;
		} else if (inp_p[0] == '*' && inp_p[1] == '/')
			goto end_of_comment;
		else
			copy_comment_wrap_text(line_length, &last_blank);
	}

end_of_comment:
	copy_comment_wrap_finish(line_length, delim);
	return;

unterminated_comment:
	diag(1, "Unterminated comment");
	output_line();
}

static void
copy_comment_nowrap(void)
{
	char kind = token.s[token.len - 1];

	for (;;) {
		if (inp_p[0] == '\n') {
			if (kind == '/')
				return;

			if (had_eof) {
				diag(1, "Unterminated comment");
				output_line();
				return;
			}

			if (com.len == 0)
				com_add_char(' ');	/* force output of an
							 * empty line */
			output_line();
			++line_no;
			inp_skip();
			continue;
		}

		com_add_char(*inp_p++);
		if (com.len >= 2
		    && com.s[com.len - 2] == '*'
		    && com.s[com.len - 1] == '/'
		    && kind == '*')
			return;
	}
}

/*
 * Scan, reformat and output a single comment, which is either a block comment
 * starting with '/' '*' or an end-of-line comment starting with '//'.
 */
void
process_comment(void)
{
	bool may_wrap, delim;
	int ind, line_length;

	analyze_comment(&may_wrap, &delim, &ind, &line_length);
	copy_comment_start(may_wrap, &delim, ind, line_length);
	if (may_wrap)
		copy_comment_wrap(line_length, delim);
	else
		copy_comment_nowrap();
}