/*-
 * Copyright (c)2004, 2005 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_utf7.h"


#include <errno.h>
#include <limits.h>
#include <stdio.h>
#include <stdint.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
 */

#define EI_MASK     UINT16_C(0xff)
#define EI_DIRECT   UINT16_C(0x100)
#define EI_OPTION   UINT16_C(0x200)
#define EI_SPACE    UINT16_C(0x400)

typedef struct {
    uint16_t     cell[0x80];
} _UTF7EncodingInfo;

typedef struct {
    unsigned int
        mode: 1,    /* whether base64 mode */
        bits: 4,    /* need to hold 0 - 15 */
        cache: 22;  /* 22 = BASE64_BIT + UTF16_BIT */
    int chlen;
    char ch[4]; /* BASE64_IN, 3 * 6 = 18, most closed to UTF16_BIT */
} _UTF7State;

#define _CEI_TO_EI(_cei_)       (&(_cei_)->ei)
#define _CEI_TO_STATE(_cei_, _func_)    (_cei_)->states.s_##_func_

#define _FUNCNAME(m)            _citrus_UTF7_##m
#define _ENCODING_INFO          _UTF7EncodingInfo
#define _ENCODING_STATE         _UTF7State
#define _ENCODING_MB_CUR_MAX(_ei_)      4
#define _ENCODING_IS_STATE_DEPENDENT        1
#define _STATE_NEEDS_EXPLICIT_INIT(_ps_)    0

static __inline void
/*ARGSUSED*/
_citrus_UTF7_init_state(_UTF7EncodingInfo * ei ,
    _UTF7State * s)
{
    (void) ei;
    memset((void *)s, 0, sizeof(*s));
}

static const char base64[] =
    "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    "abcdefghijklmnopqrstuvwxyz"
    "0123456789+/";

static const char direct[] =
    "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    "abcdefghijklmnopqrstuvwxyz"
    "0123456789'(),-./:?";

static const char option[] = "!\"#$%&*;<=>@[]^_`{|}";
static const char spaces[] = " \t\r\n";

#define BASE64_BIT  6
#define UTF16_BIT   16

#define BASE64_MAX  0x3f
#define UTF16_MAX   UINT16_C(0xffff)
#define UTF32_MAX   UINT32_C(0x10ffff)

#define BASE64_IN   '+'
#define BASE64_OUT  '-'

#define SHIFT7BIT(c)    ((c) >> 7)
#define ISSPECIAL(c)    ((c) == '\0' || (c) == BASE64_IN)

#define FINDLEN(ei, c) \
    (SHIFT7BIT((c)) ? -1 : (((ei)->cell[(c)] & EI_MASK) - 1))

#define ISDIRECT(ei, c) (!SHIFT7BIT((c)) && (ISSPECIAL((c)) || \
    ei->cell[(c)] & (EI_DIRECT | EI_OPTION | EI_SPACE)))

#define ISSAFE(ei, c)   (!SHIFT7BIT((c)) && (ISSPECIAL((c)) || \
    (c < 0x80 && ei->cell[(c)] & (EI_DIRECT | EI_SPACE))))

/* surrogate pair */
#define SRG_BASE    UINT32_C(0x10000)
#define HISRG_MIN   UINT16_C(0xd800)
#define HISRG_MAX   UINT16_C(0xdbff)
#define LOSRG_MIN   UINT16_C(0xdc00)
#define LOSRG_MAX   UINT16_C(0xdfff)

static int
_citrus_UTF7_mbtoutf16(_UTF7EncodingInfo * ei,
    uint16_t * u16, char ** s, size_t n,
    _UTF7State * psenc, size_t * nresult)
{
    char *s0;
    int done, i, len;

    *nresult = 0;
    s0 = *s;

    for (i = 0, done = 0; done == 0; i++) {
        if (i == psenc->chlen) {
            if (n-- < 1) {
                *nresult = (size_t)-2;
                *s = s0;
                return (0);
            }
            psenc->ch[psenc->chlen++] = *s0++;
        }
        if (SHIFT7BIT((int)psenc->ch[i]))
            goto ilseq;
        if (!psenc->mode) {
            if (psenc->bits > 0 || psenc->cache > 0)
                return (EINVAL);
            if (psenc->ch[i] == BASE64_IN)
                psenc->mode = 1;
            else {
                if (!ISDIRECT(ei, (int)psenc->ch[i]))
                    goto ilseq;
                *u16 = (uint16_t)psenc->ch[i];
                done = 1;
                continue;
            }
        } else {
            if (psenc->ch[i] == BASE64_OUT && psenc->cache == 0) {
                psenc->mode = 0;
                *u16 = (uint16_t)BASE64_IN;
                done = 1;
                continue;
            }
            len = FINDLEN(ei, (int)psenc->ch[i]);
            if (len < 0) {
                if (psenc->bits >= BASE64_BIT)
                    return (EINVAL);
                psenc->mode = 0;
                psenc->bits = psenc->cache = 0;
                if (psenc->ch[i] != BASE64_OUT) {
                    if (!ISDIRECT(ei, (int)psenc->ch[i]))
                        goto ilseq;
                    *u16 = (uint16_t)psenc->ch[i];
                    done = 1;
                } else {
                    psenc->chlen--;
                    i--;
                }
            } else {
                psenc->cache =
                    (psenc->cache << BASE64_BIT) | len;
                switch (psenc->bits) {
                case 0: case 2: case 4: case 6: case 8:
                    psenc->bits += BASE64_BIT;
                    break;
                case 10: case 12: case 14:
                    psenc->bits -= (UTF16_BIT - BASE64_BIT);
                    *u16 = (psenc->cache >> psenc->bits) &
                        UTF16_MAX;
                    done = 1;
                    break;
                default:
                    return (EINVAL);
                }
            }
        }
    }

    if (psenc->chlen > i)
        return (EINVAL);
    psenc->chlen = 0;
    *nresult = (size_t)((*u16 == 0) ? 0 : s0 - *s);
    *s = s0;

    return (0);

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

static int
_citrus_UTF7_mbrtowc_priv(_UTF7EncodingInfo * ei,
    _citrus_wc_t * pwc, char ** s, size_t n,
    _UTF7State * psenc, size_t * nresult)
{
    uint32_t u32;
    uint16_t hi, lo;
    size_t nr, siz;
    int err;

    if (*s == NULL) {
        _citrus_UTF7_init_state(ei, psenc);
        *nresult = (size_t)_ENCODING_IS_STATE_DEPENDENT;
        return (0);
    }
    err = _citrus_UTF7_mbtoutf16(ei, &hi, s, n, psenc, &nr);
    if (nr == (size_t)-1 || nr == (size_t)-2) {
        *nresult = nr;
        return (err);
    }
    if (err != 0)
        return (err);
    n -= nr;
    siz = nr;
    if (hi < HISRG_MIN || hi > HISRG_MAX) {
        u32 = (uint32_t)hi;
        goto done;
    }
    err = _citrus_UTF7_mbtoutf16(ei, &lo, s, n, psenc, &nr);
    if (nr == (size_t)-1 || nr == (size_t)-2) {
        psenc->chlen = 1; /* make get_state_desc return incomplete */
        *nresult = nr;
        return (err);
    }
    if (err != 0)
        return (err);
    if (lo < LOSRG_MIN || lo > LOSRG_MAX) {
        *nresult = (size_t)-1;
        return (EILSEQ);
    }
    hi -= HISRG_MIN;
    lo -= LOSRG_MIN;
    u32 = (hi << 10 | lo) + SRG_BASE;
    siz += nr;
done:
    if (pwc != NULL)
        *pwc = (_citrus_wc_t)u32;
    if (u32 == (uint32_t)0) {
        *nresult = (size_t)0;
        _citrus_UTF7_init_state(ei, psenc);
    } else {
        *nresult = siz;
    }
    return (err);
}

static int
_citrus_UTF7_utf16tomb(_UTF7EncodingInfo * ei,
    char * s, size_t n , uint16_t u16,
    _UTF7State * psenc, size_t * nresult)
{
    int bits, i;

    (void) n;

    if (psenc->chlen != 0 || psenc->bits > BASE64_BIT)
        return (EINVAL);

    if (ISSAFE(ei, u16)) {
        if (psenc->mode) {
            if (psenc->bits > 0) {
                bits = BASE64_BIT - psenc->bits;
                i = (psenc->cache << bits) & BASE64_MAX;
                psenc->ch[psenc->chlen++] = base64[i];
                psenc->bits = psenc->cache = 0;
            }
            if (u16 == BASE64_OUT || FINDLEN(ei, u16) >= 0)
                psenc->ch[psenc->chlen++] = BASE64_OUT;
            psenc->mode = 0;
        }
        if (psenc->bits != 0)
            return (EINVAL);
        psenc->ch[psenc->chlen++] = (char)u16;
        if (u16 == BASE64_IN)
            psenc->ch[psenc->chlen++] = BASE64_OUT;
    } else {
        if (!psenc->mode) {
            if (psenc->bits > 0)
                return (EINVAL);
            psenc->ch[psenc->chlen++] = BASE64_IN;
            psenc->mode = 1;
        }
        psenc->cache = (psenc->cache << UTF16_BIT) | u16;
        bits = UTF16_BIT + psenc->bits;
        psenc->bits = bits % BASE64_BIT;
        while ((bits -= BASE64_BIT) >= 0) {
            i = (psenc->cache >> bits) & BASE64_MAX;
            psenc->ch[psenc->chlen++] = base64[i];
        }
    }
    memcpy(s, psenc->ch, psenc->chlen);
    *nresult = psenc->chlen;
    psenc->chlen = 0;

    return (0);
}

static int
_citrus_UTF7_wcrtomb_priv(_UTF7EncodingInfo * ei,
    char * s, size_t n, _citrus_wc_t wchar,
    _UTF7State * psenc, size_t * nresult)
{
    uint32_t u32;
    uint16_t u16[2];
    int err, i, len;
    size_t nr, siz;

    u32 = (uint32_t)wchar;
    if (u32 <= UTF16_MAX) {
        u16[0] = (uint16_t)u32;
        len = 1;
    } else if (u32 <= UTF32_MAX) {
        u32 -= SRG_BASE;
        u16[0] = (uint16_t) ((u32 >> 10) + HISRG_MIN);
        u16[1] = ((uint16_t)(u32 & UINT32_C(0x3ff))) + LOSRG_MIN;
        len = 2;
    } else {
        *nresult = (size_t)-1;
        return (EILSEQ);
    }
    siz = 0;
    for (i = 0; i < len; ++i) {
        err = _citrus_UTF7_utf16tomb(ei, s, n, u16[i], psenc, &nr);
        if (err != 0)
            return (err); /* XXX: state has been modified */
        s += nr;
        n -= nr;
        siz += nr;
    }
    *nresult = siz;

    return (0);
}

static int
/* ARGSUSED */
_citrus_UTF7_put_state_reset(_UTF7EncodingInfo * ei ,
    char * s, size_t n, _UTF7State * psenc,
    size_t * nresult)
{
    int bits, pos;
    (void) ei;

    if (psenc->chlen != 0 || psenc->bits > BASE64_BIT)
        return (EINVAL);

    if (psenc->mode) {
        if (psenc->bits > 0) {
            if (n-- < 1)
                return (E2BIG);
            bits = BASE64_BIT - psenc->bits;
            pos = (psenc->cache << bits) & BASE64_MAX;
            psenc->ch[psenc->chlen++] = base64[pos];
            psenc->ch[psenc->chlen++] = BASE64_OUT;
            psenc->bits = psenc->cache = 0;
        }
        psenc->mode = 0;
    }
    if (psenc->bits != 0)
        return (EINVAL);
    if (n-- < 1)
        return (E2BIG);

    *nresult = (size_t)psenc->chlen;
    if (psenc->chlen > 0) {
        memcpy(s, psenc->ch, psenc->chlen);
        psenc->chlen = 0;
    }

    return (0);
}

static __inline int
/*ARGSUSED*/
_citrus_UTF7_stdenc_wctocs(_UTF7EncodingInfo * 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_UTF7_stdenc_cstowc(_UTF7EncodingInfo * 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_UTF7_stdenc_get_state_desc_generic(_UTF7EncodingInfo * ei ,
    _UTF7State * psenc, int * rstate)
{
    (void) ei;

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

static void
/*ARGSUSED*/
_citrus_UTF7_encoding_module_uninit(_UTF7EncodingInfo *ei )
{
    (void) ei;

    /* ei seems to be unused */
}

static int
/*ARGSUSED*/
_citrus_UTF7_encoding_module_init(_UTF7EncodingInfo * ei,
    const void * var , size_t lenvar )
{
    const char *s;
    (void) var;
    (void) lenvar;

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

#define FILL(str, flag)             \
do {                        \
    for (s = str; *s != '\0'; s++)      \
        ei->cell[*s & 0x7f] |= flag;    \
} while (/*CONSTCOND*/0)

    FILL(base64, (s - base64) + 1);
    FILL(direct, EI_DIRECT);
    FILL(option, EI_OPTION);
    FILL(spaces, EI_SPACE);

    return (0);
}

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

_CITRUS_STDENC_DECLS(UTF7);
_CITRUS_STDENC_DEF_OPS(UTF7);

#include "citrus_stdenc_template.h"