/*
 * Copyright (C) 1984-2012  Mark Nudelman
 * Modified for use with illumos by Garrett D'Amore.
 * Copyright 2014 Garrett D'Amore <garrett@damore.org>
 *
 * You may distribute under the terms of either the GNU General Public
 * License or the Less License, as specified in the README file.
 *
 * For more information, see the README file.
 */

/*
 * Routines to do pattern matching.
 */

#include "less.h"
#include "pattern.h"

extern int caseless;
extern int less_is_more;

/*
 * Compile a search pattern, for future use by match_pattern.
 */
static int
compile_pattern2(char *pattern, int search_type, regex_t **comp_pattern)
{
        regex_t *comp;

        if (search_type & SRCH_NO_REGEX)
                return (0);
        comp = ecalloc(1, sizeof (regex_t));
        if (regcomp(comp, pattern, less_is_more ? 0 : REGCOMP_FLAG)) {
                free(comp);
                error("Invalid pattern", NULL);
                return (-1);
        }
        if (*comp_pattern != NULL)
                regfree(*comp_pattern);
        *comp_pattern = comp;
        return (0);
}

/*
 * Like compile_pattern2, but convert the pattern to lowercase if necessary.
 */
int
compile_pattern(char *pattern, int search_type, regex_t **comp_pattern)
{
        char *cvt_pattern;
        int result;

        if (caseless != OPT_ONPLUS) {
                cvt_pattern = pattern;
        } else {
                cvt_pattern = ecalloc(1, cvt_length(strlen(pattern)));
                cvt_text(cvt_pattern, pattern, NULL, NULL, CVT_TO_LC);
        }
        result = compile_pattern2(cvt_pattern, search_type, comp_pattern);
        if (cvt_pattern != pattern)
                free(cvt_pattern);
        return (result);
}

/*
 * Forget that we have a compiled pattern.
 */
void
uncompile_pattern(regex_t **pattern)
{
        if (*pattern != NULL)
                regfree(*pattern);
        *pattern = NULL;
}

/*
 * Simple pattern matching function.
 * It supports no metacharacters like *, etc.
 */
static int
match(char *pattern, int pattern_len, char *buf, int buf_len,
    char **pfound, char **pend)
{
        char *pp, *lp;
        char *pattern_end = pattern + pattern_len;
        char *buf_end = buf + buf_len;

        for (; buf < buf_end; buf++) {
                for (pp = pattern, lp = buf; *pp == *lp; pp++, lp++)
                        if (pp == pattern_end || lp == buf_end)
                                break;
                if (pp == pattern_end) {
                        if (pfound != NULL)
                                *pfound = buf;
                        if (pend != NULL)
                                *pend = lp;
                        return (1);
                }
        }
        return (0);
}

/*
 * Perform a pattern match with the previously compiled pattern.
 * Set sp and ep to the start and end of the matched string.
 */
int
match_pattern(void *pattern, char *tpattern, char *line, int line_len,
    char **sp, char **ep, int notbol, int search_type)
{
        int matched;
        regex_t *spattern = (regex_t *)pattern;

        if (search_type & SRCH_NO_REGEX) {
                matched = match(tpattern, strlen(tpattern), line, line_len,
                    sp, ep);
        } else {
                regmatch_t rm;
                int flags = (notbol) ? REG_NOTBOL : 0;
#ifdef  REG_STARTEND
                flags |= REG_STARTEND;
                rm.rm_so = 0;
                rm.rm_eo = line_len;
#endif
                *sp = NULL;
                *ep = NULL;
                matched = !regexec(spattern, line, 1, &rm, flags);
                if (matched) {
                        *sp = line + rm.rm_so;
                        *ep = line + rm.rm_eo;
                }
        }
        matched = (!(search_type & SRCH_NO_MATCH) && matched) ||
            ((search_type & SRCH_NO_MATCH) && !matched);
        return (matched);
}