/* Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include <string.h>

#define C_LUCY_STRINGHELPER
#define LUCY_USE_SHORT_NAMES

#include "Lucy/Util/StringHelper.h"

const uint8_t lucy_StrHelp_UTF8_COUNT[] = {
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
    2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
    3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
    4, 4, 4, 4, 4, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
};

size_t
StrHelp_overlap(const char *a, const char *b, size_t a_len,  size_t b_len) {
    size_t i;
    const size_t len = a_len <= b_len ? a_len : b_len;

    for (i = 0; i < len; i++) {
        if (*a++ != *b++) { break; }
    }
    return i;
}

static const char base36_chars[] = "0123456789abcdefghijklmnopqrstuvwxyz";

size_t
StrHelp_to_base36(uint64_t num, void *buffer) {
    char  my_buf[StrHelp_MAX_BASE36_BYTES];
    char *buf = my_buf + StrHelp_MAX_BASE36_BYTES - 1;
    char *end = buf;

    // Null terminate.
    *buf = '\0';

    // Convert to base 36 characters.
    do {
        *(--buf) = base36_chars[num % 36];
        num /= 36;
    } while (num > 0);

    size_t size = (size_t)(end - buf);
    memcpy(buffer, buf, size + 1);
    return size;
}

const char*
StrHelp_back_utf8_char(const char *ptr, const char *start) {
    while (--ptr >= start) {
        if ((*ptr & 0xC0) != 0x80) { return ptr; }
    }
    return NULL;
}