/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright 2013 Garrett D'Amore <garrett@damore.org>
 * Copyright 2010 Nexenta Systems, Inc.  All rights reserved.
 * Copyright (c) 2004 Tim J. Robbins. All rights reserved.
 * Copyright (c) 2003 David Xu <davidxu@freebsd.org>
 * All rights reserved.
 *
 * Copyright (c) 2011 The FreeBSD Foundation
 *
 * Portions of this software were developed by David Chisnall
 * under sponsorship from the FreeBSD Foundation.
 *
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
 */

#include <sys/param.h>
#include <errno.h>
#include <runetype.h>
#include <stdlib.h>
#include <string.h>
#include <wchar.h>
#include "mblocal.h"

static size_t   _GB2312_mbrtowc(wchar_t * __restrict, const char * __restrict,
                    size_t, mbstate_t * __restrict);
static int      _GB2312_mbsinit(const mbstate_t *);
static size_t   _GB2312_wcrtomb(char * __restrict, wchar_t,
                    mbstate_t * __restrict);
static size_t   _GB2312_mbsnrtowcs(wchar_t * __restrict,
                    const char ** __restrict, size_t, size_t,
                    mbstate_t * __restrict);
static size_t   _GB2312_wcsnrtombs(char * __restrict,
                    const wchar_t ** __restrict, size_t, size_t,
                    mbstate_t * __restrict);


typedef struct {
        int     count;
        u_char  bytes[2];
} _GB2312State;

int
_GB2312_init(struct xlocale_ctype *l, _RuneLocale *rl)
{

        l->runes = rl;
        l->__mbrtowc = _GB2312_mbrtowc;
        l->__wcrtomb = _GB2312_wcrtomb;
        l->__mbsinit = _GB2312_mbsinit;
        l->__mbsnrtowcs = _GB2312_mbsnrtowcs;
        l->__wcsnrtombs = _GB2312_wcsnrtombs;
        l->__mb_cur_max = 2;
        l->__mb_sb_limit = 128;
        return (0);
}

static int
_GB2312_mbsinit(const mbstate_t *ps)
{

        return (ps == NULL || ((const _GB2312State *)ps)->count == 0);
}

static int
_GB2312_check(const char *str, size_t n)
{
        const u_char *s = (const u_char *)str;

        if (n == 0)
                /* Incomplete multibyte sequence */
                return (-2);
        if (s[0] >= 0xa1 && s[0] <= 0xfe) {
                if (n < 2)
                        /* Incomplete multibyte sequence */
                        return (-2);
                if (s[1] < 0xa1 || s[1] > 0xfe)
                        /* Invalid multibyte sequence */
                        return (-1);
                return (2);
        } else if (s[0] & 0x80) {
                /* Invalid multibyte sequence */
                return (-1);
        }
        return (1);
}

static size_t
_GB2312_mbrtowc(wchar_t * __restrict pwc, const char * __restrict s, size_t n,
    mbstate_t * __restrict ps)
{
        _GB2312State *gs;
        wchar_t wc;
        int i, len, ocount;
        size_t ncopy;

        gs = (_GB2312State *)ps;

        if (gs->count < 0 || gs->count > sizeof(gs->bytes)) {
                errno = EINVAL;
                return ((size_t)-1);
        }

        if (s == NULL) {
                s = "";
                n = 1;
                pwc = NULL;
        }

        ncopy = MIN(MIN(n, MB_CUR_MAX), sizeof(gs->bytes) - gs->count);
        memcpy(gs->bytes + gs->count, s, ncopy);
        ocount = gs->count;
        gs->count += ncopy;
        s = (char *)gs->bytes;
        n = gs->count;

        if ((len = _GB2312_check(s, n)) < 0)
                return ((size_t)len);
        wc = 0;
        i = len;
        while (i-- > 0)
                wc = (wc << 8) | (unsigned char)*s++;
        if (pwc != NULL)
                *pwc = wc;
        gs->count = 0;
        return (wc == L'\0' ? 0 : len - ocount);
}

static size_t
_GB2312_wcrtomb(char * __restrict s, wchar_t wc, mbstate_t * __restrict ps)
{
        _GB2312State *gs;

        gs = (_GB2312State *)ps;

        if (gs->count != 0) {
                errno = EINVAL;
                return ((size_t)-1);
        }

        if (s == NULL)
                /* Reset to initial shift state (no-op) */
                return (1);
        if (wc & 0x8000) {
                *s++ = (wc >> 8) & 0xff;
                *s = wc & 0xff;
                return (2);
        }
        *s = wc & 0xff;
        return (1);
}

static size_t
_GB2312_mbsnrtowcs(wchar_t * __restrict dst,
    const char ** __restrict src, size_t nms, size_t len,
    mbstate_t * __restrict ps)
{
        return (__mbsnrtowcs_std(dst, src, nms, len, ps, _GB2312_mbrtowc));
}

static size_t
_GB2312_wcsnrtombs(char * __restrict dst,
    const wchar_t ** __restrict src, size_t nwc, size_t len,
    mbstate_t * __restrict ps)
{
        return (__wcsnrtombs_std(dst, src, nwc, len, ps, _GB2312_wcrtomb));
}