/*
 * Copyright (c) 1988 Mark Nudleman
 * Copyright (c) 1988, 1993
 *	The Regents of the University of California.  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.
 */

#ifndef lint
static char sccsid[] = "@(#)prim.c	8.1 (Berkeley) 6/6/93";
#endif /* not lint */

#ifndef lint
static const char rcsid[] =
  "$FreeBSD: src/usr.bin/more/prim.c,v 1.10 2000/05/14 03:30:59 hoek Exp $";
#endif /* not lint */

/*
 * Primitives for displaying the file on the screen.
 */

#include <sys/types.h>

#include <assert.h>
#include <ctype.h>
#include <limits.h>
#include <regex.h>
#include <stdio.h>

#include "less.h"

extern int sigs;
extern int top_scroll;
extern int sc_width, sc_height;
extern int horiz_off;
extern int wraplines;
extern int caseless;
extern int linenums;
extern int tagoption;
extern char *line;
extern int retain_below;

/*
 * Search for the n-th occurence of a specified pattern,
 * either forward or backward.
 */
search(search_forward, pattern, n, wantmatch)
	register int search_forward;
	register char *pattern;
	register int n;
	int wantmatch;
{
	off_t pos, linepos;
	register char *p;
	register char *q;
	int linenum;
	int linematch;
	static regex_t rx;
	static int oncethru;
	int regerr;
	char errbuf[_POSIX2_LINE_MAX];

	if (pattern && pattern[0]) {
		if (oncethru) {
			regfree(&rx);
		}

		regerr = regcomp(&rx, pattern, (REG_EXTENDED | REG_NOSUB
						| (caseless ? REG_ICASE : 0)));

		if (regerr) {
			regerror(regerr, &rx, errbuf, sizeof errbuf);
			error(errbuf);
			oncethru = 0;
			regfree(&rx);
			return (0);
		}
		oncethru = 1;
	} else if (!oncethru) {
		error("No previous regular expression");
		return (0);
	}

	/*
	 * Figure out where to start the search.
	 *
	 * XXX This should probably be adapted to handle horizontal
	 * scrolling.  Consider a long line at the top of the screen
	 * that might be hiding more matches to its right (when doing
	 * successive searches).
	 */

	if (position(TOP) == NULL_POSITION) {
		/*
		 * Nothing is currently displayed.  Start at the beginning
		 * of the file.  (This case is mainly for searches from the
		 * command line.
		 */
		pos = (off_t)0;
	} else if (!search_forward) {
		/*
		 * Backward search: start just before the top line
		 * displayed on the screen.
		 */
		pos = position(TOP);
	} else {
		/*
		 * Start at the second screen line displayed on the screen.
		 */
		pos = position(TOP_PLUS_ONE);
	}

	if (pos == NULL_POSITION)
	{
		/*
		 * Can't find anyplace to start searching from.
		 */
		error("Nothing to search");
		return(0);
	}

	linenum = find_linenum(pos);
	for (;;)
	{
		/*
		 * Get lines until we find a matching one or
		 * until we hit end-of-file (or beginning-of-file
		 * if we're going backwards).
		 */
		if (sigs)
			/*
			 * A signal aborts the search.
			 */
			return(0);

		if (search_forward)
		{
			/*
			 * Read the next line, and save the
			 * starting position of that line in linepos.
			 */
			linepos = pos;
			pos = forw_raw_line(pos);
			if (linenum != 0)
				linenum++;
		} else
		{
			/*
			 * Read the previous line and save the
			 * starting position of that line in linepos.
			 */
			pos = back_raw_line(pos);
			linepos = pos;
			if (linenum != 0)
				linenum--;
		}

		if (pos == NULL_POSITION)
		{
			/*
			 * We hit EOF/BOF without a match.
			 */
			error("Pattern not found");
			return(0);
		}

		/*
		 * If we're using line numbers, we might as well
		 * remember the information we have now (the position
		 * and line number of the current line).
		 */
		if (linenums)
			add_lnum(linenum, pos);

		/*
		 * Remove any backspaces along with the preceeding char.
		 * This allows us to match text which is underlined or
		 * overstruck.
		 */
		for (p = q = line;  *p;  p++, q++)
			if (q > line && *p == '\b')
				/* Delete BS and preceeding char. */
				q -= 2;
			else
				/* Otherwise, just copy. */
				*q = *p;

		/*
		 * Test the next line to see if we have a match.
		 */
		linematch = !regexec(&rx, line, 0, 0, 0);

		/*
		 * We are successful if wantmatch and linematch are
		 * both true (want a match and got it),
		 * or both false (want a non-match and got it).
		 */
		if (((wantmatch && linematch) || (!wantmatch && !linematch)) &&
		      --n <= 0)
			/*
			 * Found the line.
			 */
			break;
	}
	jump_loc(linepos);
	return(1);
}