/**
 * Copyright (c) 2011-2025 Bill Greiman
 * This file is part of the SdFat library for SD memory cards.
 *
 * MIT License
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included
 * in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 */
#include "FsUtf.h"
namespace FsUtf
{
//----------------------------------------------------------------------------
char *cpToMb(uint32_t cp, char *str, const char *end)
{
    size_t n = end - str;
    if (cp < 0X80)
    {
        if (n < 1)
            goto fail;
        *(str++) = static_cast<uint8_t>(cp);
    }
    else if (cp < 0X800)
    {
        if (n < 2)
            goto fail;
        *(str++) = static_cast<uint8_t>((cp >> 6) | 0XC0);
        *(str++) = static_cast<uint8_t>((cp & 0X3F) | 0X80);
    }
    else if (cp < 0X10000)
    {
        if (n < 3)
            goto fail;
        *(str++) = static_cast<uint8_t>((cp >> 12) | 0XE0);
        *(str++) = static_cast<uint8_t>(((cp >> 6) & 0X3F) | 0X80);
        *(str++) = static_cast<uint8_t>((cp & 0X3F) | 0X80);
    }
    else
    {
        if (n < 4)
            goto fail;
        *(str++) = static_cast<uint8_t>((cp >> 18) | 0XF0);
        *(str++) = static_cast<uint8_t>(((cp >> 12) & 0X3F) | 0X80);
        *(str++) = static_cast<uint8_t>(((cp >> 6) & 0X3F) | 0X80);
        *(str++) = static_cast<uint8_t>((cp & 0X3F) | 0X80);
    }
    return str;

fail:
    return nullptr;
}
//----------------------------------------------------------------------------
// to do?  improve error check
const char *mbToCp(const char *str, const char *end, uint32_t *rtn)
{
    size_t n;
    uint32_t cp;
    if (str >= end)
    {
        return nullptr;
    }
    uint8_t ch = str[0];
    if ((ch & 0X80) == 0)
    {
        *rtn = ch;
        return str + 1;
    }
    if ((ch & 0XE0) == 0XC0)
    {
        cp = ch & 0X1F;
        n = 2;
    }
    else if ((ch & 0XF0) == 0XE0)
    {
        cp = ch & 0X0F;
        n = 3;
    }
    else if ((ch & 0XF8) == 0XF0)
    {
        cp = ch & 0X07;
        n = 4;
    }
    else
    {
        return nullptr;
    }
    if ((str + n) > end)
    {
        return nullptr;
    }
    for (size_t i = 1; i < n; i++)
    {
        ch = str[i];
        if ((ch & 0XC0) != 0X80)
        {
            return nullptr;
        }
        cp <<= 6;
        cp |= ch & 0X3F;
    }
    // Don't allow over long as ASCII.
    if (cp < 0X80 || !isValidCp(cp))
    {
        return nullptr;
    }
    *rtn = cp;
    return str + n;
}
//----------------------------------------------------------------------------
const char *mbToU16(const char *str, const char *end, uint16_t *hs, uint16_t *ls)
{
    uint32_t cp;
    const char *ptr = mbToCp(str, end, &cp);
    if (!ptr)
    {
        return nullptr;
    }
    if (cp <= 0XFFFF)
    {
        *hs = cp;
        *ls = 0;
    }
    else
    {
        *hs = highSurrogate(cp);
        *ls = lowSurrogate(cp);
    }
    return ptr;
}
} // namespace FsUtf
