/*-
 * Copyright (c)2003 Citrus Project,
 * 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.
 *
 * 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 "dcmtk/config/osconfig.h"
#include "citrus_utf1632.h"

#include <sys/types.h>
#include <errno.h>
#include <limits.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <wchar.h>

#include "citrus_bcs.h"
#include "citrus_types.h"
#include "citrus_module.h"
#include "citrus_stdenc.h"



/* ----------------------------------------------------------------------
 * private stuffs used by templates
 */

typedef struct {
    int      chlen;
    int      current_endian;
    uint8_t      ch[4];
} _UTF1632State;

#define _ENDIAN_UNKNOWN     0
#define _ENDIAN_BIG     1
#define _ENDIAN_LITTLE      2
#if BYTE_ORDER == BIG_ENDIAN
#define _ENDIAN_INTERNAL    _ENDIAN_BIG
#define _ENDIAN_SWAPPED     _ENDIAN_LITTLE
#else
#define _ENDIAN_INTERNAL    _ENDIAN_LITTLE
#define _ENDIAN_SWAPPED _ENDIAN_BIG
#endif
#define _MODE_UTF32     0x00000001U
#define _MODE_FORCE_ENDIAN  0x00000002U

typedef struct {
    int      preffered_endian;
    unsigned int     cur_max;
    unsigned int     cur_min;
    uint32_t     mode;
} _UTF1632EncodingInfo;

#define _FUNCNAME(m)            _citrus_UTF1632_##m
#define _ENCODING_INFO          _UTF1632EncodingInfo
#define _ENCODING_STATE         _UTF1632State
#define _ENCODING_MB_CUR_MAX(_ei_)  ((_ei_)->cur_max)
#define _ENCODING_MB_CUR_MIN(_ei_)  ((_ei_)->cur_min)
#define _ENCODING_IS_STATE_DEPENDENT    0
#define _STATE_NEEDS_EXPLICIT_INIT(_ps_)    0

static __inline void
/*ARGSUSED*/
_citrus_UTF1632_init_state(_UTF1632EncodingInfo *ei ,
    _UTF1632State *s)
{
    (void) ei;
    memset(s, 0, sizeof(*s));
}

static int
_citrus_UTF1632_mbrtowc_priv(_UTF1632EncodingInfo *ei, _citrus_wc_t *pwc,
    char **s, size_t n, _UTF1632State *psenc, size_t *nresult)
{
    char *s0;
    size_t result;
    _citrus_wc_t wc = L'\0';
    int chlenbak, endian, needlen;

    s0 = *s;

    if (s0 == NULL) {
        _citrus_UTF1632_init_state(ei, psenc);
        *nresult = 0; /* state independent */
        return (0);
    }

    result = 0;
    chlenbak = psenc->chlen;

refetch:
    needlen = ((ei->mode & _MODE_UTF32) != 0 || chlenbak >= 2) ? 4 : 2;

    while (chlenbak < needlen) {
        if (n == 0)
            goto restart;
        psenc->ch[chlenbak++] = *s0++;
        n--;
        result++;
    }

    /* judge endian marker */
    if ((ei->mode & _MODE_UTF32) == 0) {
        /* UTF16 */
        if (psenc->ch[0] == 0xFE && psenc->ch[1] == 0xFF) {
            psenc->current_endian = _ENDIAN_BIG;
            chlenbak = 0;
            goto refetch;
        } else if (psenc->ch[0] == 0xFF && psenc->ch[1] == 0xFE) {
            psenc->current_endian = _ENDIAN_LITTLE;
            chlenbak = 0;
            goto refetch;
        }
    } else {
        /* UTF32 */
        if (psenc->ch[0] == 0x00 && psenc->ch[1] == 0x00 &&
            psenc->ch[2] == 0xFE && psenc->ch[3] == 0xFF) {
            psenc->current_endian = _ENDIAN_BIG;
            chlenbak = 0;
            goto refetch;
        } else if (psenc->ch[0] == 0xFF && psenc->ch[1] == 0xFE &&
               psenc->ch[2] == 0x00 && psenc->ch[3] == 0x00) {
            psenc->current_endian = _ENDIAN_LITTLE;
            chlenbak = 0;
            goto refetch;
        }
    }
    endian = ((ei->mode & _MODE_FORCE_ENDIAN) != 0 ||
        psenc->current_endian == _ENDIAN_UNKNOWN) ? ei->preffered_endian :
        psenc->current_endian;

    /* get wc */
    if ((ei->mode & _MODE_UTF32) == 0) {
        /* UTF16 */
        if (needlen == 2) {
            switch (endian) {
            case _ENDIAN_LITTLE:
                wc = (psenc->ch[0] |
                    ((_citrus_wc_t)psenc->ch[1] << 8));
                break;
            case _ENDIAN_BIG:
                wc = (psenc->ch[1] |
                    ((_citrus_wc_t)psenc->ch[0] << 8));
                break;
            default:
                goto ilseq;
            }
            if (wc >= 0xD800 && wc <= 0xDBFF) {
                /* surrogate high */
                needlen = 4;
                goto refetch;
            }
        } else {
            /* surrogate low */
            wc -= 0xD800; /* wc : surrogate high (see above) */
            wc <<= 10;
            switch (endian) {
            case _ENDIAN_LITTLE:
                if (psenc->ch[3] < 0xDC || psenc->ch[3] > 0xDF)
                    goto ilseq;
                wc |= psenc->ch[2];
                wc |= (_citrus_wc_t)(psenc->ch[3] & 3) << 8;
                break;
            case _ENDIAN_BIG:
                if (psenc->ch[2]<0xDC || psenc->ch[2]>0xDF)
                    goto ilseq;
                wc |= psenc->ch[3];
                wc |= (_citrus_wc_t)(psenc->ch[2] & 3) << 8;
                break;
            default:
                goto ilseq;
            }
            wc += 0x10000;
        }
    } else {
        /* UTF32 */
        switch (endian) {
        case _ENDIAN_LITTLE:
            wc = (psenc->ch[0] |
                ((_citrus_wc_t)psenc->ch[1] << 8) |
                ((_citrus_wc_t)psenc->ch[2] << 16) |
                ((_citrus_wc_t)psenc->ch[3] << 24));
            break;
        case _ENDIAN_BIG:
            wc = (psenc->ch[3] |
                ((_citrus_wc_t)psenc->ch[2] << 8) |
                ((_citrus_wc_t)psenc->ch[1] << 16) |
                ((_citrus_wc_t)psenc->ch[0] << 24));
            break;
        default:
            goto ilseq;
        }
        if (wc >= 0xD800 && wc <= 0xDFFF)
            goto ilseq;
    }


    *pwc = wc;
    psenc->chlen = 0;
    *nresult = result;
    *s = s0;

    return (0);

ilseq:
    *nresult = (size_t)-1;
    psenc->chlen = 0;
    return (EILSEQ);

restart:
    *nresult = (size_t)-2;
    psenc->chlen = chlenbak;
    *s = s0;
    return (0);
}

static int
_citrus_UTF1632_wcrtomb_priv(_UTF1632EncodingInfo *ei, char *s, size_t n,
    _citrus_wc_t wc, _UTF1632State *psenc, size_t *nresult)
{
    _citrus_wc_t wc2;
    static const char _bom[4] = {
        0x00, 0x00, 0xFE, 0xFF,
    };
    const char *bom = &_bom[0];
    size_t cnt;

    cnt = (size_t)0;
    if (psenc->current_endian == _ENDIAN_UNKNOWN) {
        if ((ei->mode & _MODE_FORCE_ENDIAN) == 0) {
            if (ei->mode & _MODE_UTF32)
                cnt = 4;
            else {
                cnt = 2;
                bom += 2;
            }
            if (n < cnt)
                goto e2big;
            memcpy(s, bom, cnt);
            s += cnt, n -= cnt;
        }
        psenc->current_endian = ei->preffered_endian;
    }

    wc2 = 0;
    if ((ei->mode & _MODE_UTF32)==0) {
        /* UTF16 */
        if (wc > 0xFFFF) {
            /* surrogate */
            if (wc > 0x10FFFF)
                goto ilseq;
            if (n < 4)
                goto e2big;
            cnt += 4;
            wc -= 0x10000;
            wc2 = (wc & 0x3FF) | 0xDC00;
            wc = (wc>>10) | 0xD800;
        } else {
            if (n < 2)
                goto e2big;
            cnt += 2;
        }

surrogate:
        switch (psenc->current_endian) {
        case _ENDIAN_BIG:
            s[1] = (char) wc;
            s[0] = (char) (wc >>= 8);
            break;
        case _ENDIAN_LITTLE:
            s[0] = (char) wc;
            s[1] = (char) (wc >>= 8);
            break;
        }
        if (wc2 != 0) {
            wc = wc2;
            wc2 = 0;
            s += 2;
            goto surrogate;
        }
    } else {
        /* UTF32 */
        if (wc >= 0xD800 && wc <= 0xDFFF)
            goto ilseq;
        if (n < 4)
            goto e2big;
        cnt += 4;
        switch (psenc->current_endian) {
        case _ENDIAN_BIG:
            s[3] = (char) wc;
            s[2] = (char) (wc >>= 8);
            s[1] = (char) (wc >>= 8);
            s[0] = (char) (wc >>= 8);
            break;
        case _ENDIAN_LITTLE:
            s[0] = (char) wc;
            s[1] = (char) (wc >>= 8);
            s[2] = (char) (wc >>= 8);
            s[3] = (char) (wc >>= 8);
            break;
        }
    }
    *nresult = cnt;

    return (0);

ilseq:
    *nresult = (size_t)-1;
    return (EILSEQ);
e2big:
    *nresult = (size_t)-1;
    return (E2BIG);
}

static void
parse_variable(_UTF1632EncodingInfo * ei,
    const void * var, size_t lenvar)
{
    const char *p;

    p = var;
    while (lenvar > 0) {
        switch (*p) {
        case 'B':
        case 'b':
            MATCH(big, ei->preffered_endian = _ENDIAN_BIG);
            break;
        case 'L':
        case 'l':
            MATCH(little, ei->preffered_endian = _ENDIAN_LITTLE);
            break;
        case 'i':
        case 'I':
            MATCH(internal, ei->preffered_endian = _ENDIAN_INTERNAL);
            break;
        case 's':
        case 'S':
            MATCH(swapped, ei->preffered_endian = _ENDIAN_SWAPPED);
            break;
        case 'F':
        case 'f':
            MATCH(force, ei->mode |= _MODE_FORCE_ENDIAN);
            break;
        case 'U':
        case 'u':
            MATCH(utf32, ei->mode |= _MODE_UTF32);
            break;
        }
        p++;
        lenvar--;
    }
}

static int
/*ARGSUSED*/
_citrus_UTF1632_encoding_module_init(_UTF1632EncodingInfo * ei,
    const void * var, size_t lenvar)
{

    memset((void *)ei, 0, sizeof(*ei));

    parse_variable(ei, var, lenvar);

    ei->cur_min = ((ei->mode&_MODE_UTF32) == 0) ? 2 : 4;
    ei->cur_max = ((ei->mode&_MODE_UTF32) == 0) ? 6 : 8;
    /* 6: endian + surrogate */
    /* 8: endian + normal */

    if (ei->preffered_endian == _ENDIAN_UNKNOWN) {
        ei->preffered_endian = _ENDIAN_BIG;
    }

    return (0);
}

static void
/*ARGSUSED*/
_citrus_UTF1632_encoding_module_uninit(_UTF1632EncodingInfo *ei )
{
    (void) ei;
}

static __inline int
/*ARGSUSED*/
_citrus_UTF1632_stdenc_wctocs(_UTF1632EncodingInfo * ei ,
     _citrus_csid_t * csid, _citrus_index_t * idx, _citrus_wc_t wc)
{
    (void) ei;
    *csid = 0;
    *idx = (_citrus_index_t)wc;

    return (0);
}

static __inline int
/*ARGSUSED*/
_citrus_UTF1632_stdenc_cstowc(_UTF1632EncodingInfo * ei ,
    _citrus_wc_t * wc, _citrus_csid_t csid, _citrus_index_t idx)
{
    (void) ei;

    if (csid != 0)
        return (EILSEQ);

    *wc = (_citrus_wc_t)idx;

    return (0);
}

static __inline int
/*ARGSUSED*/
_citrus_UTF1632_stdenc_get_state_desc_generic(_UTF1632EncodingInfo * ei ,
    _UTF1632State * psenc, int * rstate)
{
    (void) ei;

    *rstate = (psenc->chlen == 0) ? _CITRUS_STDENC_SDGEN_INITIAL :
        _CITRUS_STDENC_SDGEN_INCOMPLETE_CHAR;
    return (0);
}

/* ----------------------------------------------------------------------
 * public interface for stdenc
 */

_CITRUS_STDENC_DECLS(UTF1632);
_CITRUS_STDENC_DEF_OPS(UTF1632);

#include "citrus_stdenc_template.h"
