/* ====================================================================
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2002 The Apache Software Foundation.  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. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Apache" and "Apache Software Foundation" must
 *    not be used to endorse or promote products derived from this
 *    software without prior written permission. For written
 *    permission, please contact apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache",
 *    nor may "Apache" appear in their name, without prior written
 *    permission of the Apache Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED 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 APACHE SOFTWARE FOUNDATION OR
 * ITS 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
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 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */

#include "apr_strmatch.h"
#include "apr_lib.h"
#define APR_WANT_STRFUNC
#include "apr_want.h"


#define NUM_CHARS  256

/*
 * String searching functions
 */
static const char *match_no_op(const apr_strmatch_pattern *this_pattern,
                               const char *s, apr_size_t slen)
{
    return s;
}

static const char *match_boyer_moore_horspool(
                               const apr_strmatch_pattern *this_pattern,
                               const char *s, apr_size_t slen)
{
    const char *s_end = s + slen;
    int *shift = (int *)(this_pattern->context);
    const char *s_next = s + this_pattern->length - 1;
    const char *p_start = this_pattern->pattern;
    const char *p_end = p_start + this_pattern->length - 1;
    while (s_next < s_end) {
        const char *s_tmp = s_next;
        const char *p_tmp = p_end;
        while (*s_tmp == *p_tmp) {
            p_tmp--;
            if (p_tmp < p_start) {
                return s_tmp;
            }
            s_tmp--;
        }
        s_next += shift[(int)*((const unsigned char *)s_next)];
    }
    return NULL;
}

static const char *match_boyer_moore_horspool_nocase(
                               const apr_strmatch_pattern *this_pattern,
                               const char *s, apr_size_t slen)
{
    const char *s_end = s + slen;
    int *shift = (int *)(this_pattern->context);
    const char *s_next = s + this_pattern->length - 1;
    const char *p_start = this_pattern->pattern;
    const char *p_end = p_start + this_pattern->length - 1;
    while (s_next < s_end) {
        const char *s_tmp = s_next;
        const char *p_tmp = p_end;
        while (apr_tolower(*s_tmp) == apr_tolower(*p_tmp)) {
            p_tmp--;
            if (p_tmp < p_start) {
                return s_tmp;
            }
            s_tmp--;
        }
        s_next += shift[(int)*((const unsigned char *)s_next)];
    }
    return NULL;
}

APU_DECLARE(const apr_strmatch_pattern *) apr_strmatch_precompile(
                                              apr_pool_t *p, const char *s,
                                              int case_sensitive)
{
    apr_strmatch_pattern *pattern;
    apr_size_t i;
    int *shift;

    pattern = apr_palloc(p, sizeof(*pattern));
    pattern->pattern = s;
    pattern->length = strlen(s);
    if (pattern->length == 0) {
        pattern->compare = match_no_op;
        pattern->context = NULL;
        return pattern;
    }

    shift = (int *)apr_palloc(p, sizeof(int) * NUM_CHARS);
    for (i = 0; i < NUM_CHARS; i++) {
        shift[i] = pattern->length;
    }
    if (case_sensitive) {
        pattern->compare = match_boyer_moore_horspool;
        for (i = 0; i < pattern->length - 1; i++) {
            shift[(int)s[i]] = pattern->length - i - 1;
        }
    }
    else {
        pattern->compare = match_boyer_moore_horspool_nocase;
        for (i = 0; i < pattern->length - 1; i++) {
            shift[apr_tolower(s[i])] = pattern->length - i - 1;
        }
    }
    pattern->context = shift;

    return pattern;
}