/*
 * cjkcodecs.h: common header for cjkcodecs
 *
 * Written by Hye-Shik Chang <perky@FreeBSD.org>
 */

#ifndef _CJKCODECS_H_
#define _CJKCODECS_H_

#define PY_SSIZE_T_CLEAN
#include "Python.h"
#include "multibytecodec.h"


/* a unicode "undefined" code point */
#define UNIINV  0xFFFE

/* internal-use DBCS code points which aren't used by any charsets */
#define NOCHAR  0xFFFF
#define MULTIC  0xFFFE
#define DBCINV  0xFFFD

/* shorter macros to save source size of mapping tables */
#define U UNIINV
#define N NOCHAR
#define M MULTIC
#define D DBCINV

struct dbcs_index {
    const ucs2_t *map;
    unsigned char bottom, top;
};
typedef struct dbcs_index decode_map;

struct widedbcs_index {
    const ucs4_t *map;
    unsigned char bottom, top;
};
typedef struct widedbcs_index widedecode_map;

struct unim_index {
    const DBCHAR *map;
    unsigned char bottom, top;
};
typedef struct unim_index encode_map;

struct unim_index_bytebased {
    const unsigned char *map;
    unsigned char bottom, top;
};

struct dbcs_map {
    const char *charset;
    const struct unim_index *encmap;
    const struct dbcs_index *decmap;
};

struct pair_encodemap {
    ucs4_t uniseq;
    DBCHAR code;
};

static const MultibyteCodec *codec_list;
static const struct dbcs_map *mapping_list;

#define CODEC_INIT(encoding)                                            \
    static int encoding##_codec_init(const void *config)

#define ENCODER_INIT(encoding)                                          \
    static int encoding##_encode_init(                                  \
        MultibyteCodec_State *state, const void *config)
#define ENCODER(encoding)                                               \
    static Py_ssize_t encoding##_encode(                                \
        MultibyteCodec_State *state, const void *config,                \
        const Py_UNICODE **inbuf, Py_ssize_t inleft,                    \
        unsigned char **outbuf, Py_ssize_t outleft, int flags)
#define ENCODER_RESET(encoding)                                         \
    static Py_ssize_t encoding##_encode_reset(                          \
        MultibyteCodec_State *state, const void *config,                \
        unsigned char **outbuf, Py_ssize_t outleft)

#define DECODER_INIT(encoding)                                          \
    static int encoding##_decode_init(                                  \
        MultibyteCodec_State *state, const void *config)
#define DECODER(encoding)                                               \
    static Py_ssize_t encoding##_decode(                                \
        MultibyteCodec_State *state, const void *config,                \
        const unsigned char **inbuf, Py_ssize_t inleft,                 \
        Py_UNICODE **outbuf, Py_ssize_t outleft)
#define DECODER_RESET(encoding)                                         \
    static Py_ssize_t encoding##_decode_reset(                          \
        MultibyteCodec_State *state, const void *config)

#if Py_UNICODE_SIZE == 4
#define UCS4INVALID(code)       \
    if ((code) > 0xFFFF)        \
    return 1;
#else
#define UCS4INVALID(code)       \
    if (0) ;
#endif

#define NEXT_IN(i)                              \
    (*inbuf) += (i);                            \
    (inleft) -= (i);
#define NEXT_OUT(o)                             \
    (*outbuf) += (o);                           \
    (outleft) -= (o);
#define NEXT(i, o)                              \
    NEXT_IN(i) NEXT_OUT(o)

#define REQUIRE_INBUF(n)                        \
    if (inleft < (n))                           \
        return MBERR_TOOFEW;
#define REQUIRE_OUTBUF(n)                       \
    if (outleft < (n))                          \
        return MBERR_TOOSMALL;

#define IN1 ((*inbuf)[0])
#define IN2 ((*inbuf)[1])
#define IN3 ((*inbuf)[2])
#define IN4 ((*inbuf)[3])

#define OUT1(c) ((*outbuf)[0]) = (c);
#define OUT2(c) ((*outbuf)[1]) = (c);
#define OUT3(c) ((*outbuf)[2]) = (c);
#define OUT4(c) ((*outbuf)[3]) = (c);

#define WRITE1(c1)              \
    REQUIRE_OUTBUF(1)           \
    (*outbuf)[0] = (c1);
#define WRITE2(c1, c2)          \
    REQUIRE_OUTBUF(2)           \
    (*outbuf)[0] = (c1);        \
    (*outbuf)[1] = (c2);
#define WRITE3(c1, c2, c3)      \
    REQUIRE_OUTBUF(3)           \
    (*outbuf)[0] = (c1);        \
    (*outbuf)[1] = (c2);        \
    (*outbuf)[2] = (c3);
#define WRITE4(c1, c2, c3, c4)  \
    REQUIRE_OUTBUF(4)           \
    (*outbuf)[0] = (c1);        \
    (*outbuf)[1] = (c2);        \
    (*outbuf)[2] = (c3);        \
    (*outbuf)[3] = (c4);

#if Py_UNICODE_SIZE == 2
# define WRITEUCS4(c)                                           \
    REQUIRE_OUTBUF(2)                                           \
    (*outbuf)[0] = 0xd800 + (((c) - 0x10000) >> 10);            \
    (*outbuf)[1] = 0xdc00 + (((c) - 0x10000) & 0x3ff);          \
    NEXT_OUT(2)
#else
# define WRITEUCS4(c)                                           \
    REQUIRE_OUTBUF(1)                                           \
    **outbuf = (Py_UNICODE)(c);                                 \
    NEXT_OUT(1)
#endif

#define _TRYMAP_ENC(m, assi, val)                               \
    ((m)->map != NULL && (val) >= (m)->bottom &&                \
        (val)<= (m)->top && ((assi) = (m)->map[(val) -          \
        (m)->bottom]) != NOCHAR)
#define TRYMAP_ENC_COND(charset, assi, uni)                     \
    _TRYMAP_ENC(&charset##_encmap[(uni) >> 8], assi, (uni) & 0xff)
#define TRYMAP_ENC(charset, assi, uni)                          \
    if TRYMAP_ENC_COND(charset, assi, uni)

#define _TRYMAP_DEC(m, assi, val)                               \
    ((m)->map != NULL && (val) >= (m)->bottom &&                \
        (val)<= (m)->top && ((assi) = (m)->map[(val) -          \
        (m)->bottom]) != UNIINV)
#define TRYMAP_DEC(charset, assi, c1, c2)                       \
    if _TRYMAP_DEC(&charset##_decmap[c1], assi, c2)

#define _TRYMAP_ENC_MPLANE(m, assplane, asshi, asslo, val)      \
    ((m)->map != NULL && (val) >= (m)->bottom &&                \
        (val)<= (m)->top &&                                     \
        ((assplane) = (m)->map[((val) - (m)->bottom)*3]) != 0 && \
        (((asshi) = (m)->map[((val) - (m)->bottom)*3 + 1]), 1) && \
        (((asslo) = (m)->map[((val) - (m)->bottom)*3 + 2]), 1))
#define TRYMAP_ENC_MPLANE(charset, assplane, asshi, asslo, uni) \
    if _TRYMAP_ENC_MPLANE(&charset##_encmap[(uni) >> 8], \
                       assplane, asshi, asslo, (uni) & 0xff)
#define TRYMAP_DEC_MPLANE(charset, assi, plane, c1, c2)         \
    if _TRYMAP_DEC(&charset##_decmap[plane][c1], assi, c2)

#if Py_UNICODE_SIZE == 2
#define DECODE_SURROGATE(c)                                     \
    if (c >> 10 == 0xd800 >> 10) { /* high surrogate */         \
        REQUIRE_INBUF(2)                                        \
        if (IN2 >> 10 == 0xdc00 >> 10) { /* low surrogate */ \
            c = 0x10000 + ((ucs4_t)(c - 0xd800) << 10) + \
            ((ucs4_t)(IN2) - 0xdc00);                           \
        }                                                       \
    }
#define GET_INSIZE(c)   ((c) > 0xffff ? 2 : 1)
#else
#define DECODE_SURROGATE(c) {;}
#define GET_INSIZE(c)   1
#endif

#define BEGIN_MAPPINGS_LIST static const struct dbcs_map _mapping_list[] = {
#define MAPPING_ENCONLY(enc) {#enc, (void*)enc##_encmap, NULL},
#define MAPPING_DECONLY(enc) {#enc, NULL, (void*)enc##_decmap},
#define MAPPING_ENCDEC(enc) {#enc, (void*)enc##_encmap, (void*)enc##_decmap},
#define END_MAPPINGS_LIST                               \
    {"", NULL, NULL} };                                 \
    static const struct dbcs_map *mapping_list =        \
        (const struct dbcs_map *)_mapping_list;

#define BEGIN_CODECS_LIST static const MultibyteCodec _codec_list[] = {
#define _STATEFUL_METHODS(enc)          \
    enc##_encode,                       \
    enc##_encode_init,                  \
    enc##_encode_reset,                 \
    enc##_decode,                       \
    enc##_decode_init,                  \
    enc##_decode_reset,
#define _STATELESS_METHODS(enc)         \
    enc##_encode, NULL, NULL,           \
    enc##_decode, NULL, NULL,
#define CODEC_STATEFUL(enc) {           \
    #enc, NULL, NULL,                   \
    _STATEFUL_METHODS(enc)              \
},
#define CODEC_STATELESS(enc) {          \
    #enc, NULL, NULL,                   \
    _STATELESS_METHODS(enc)             \
},
#define CODEC_STATELESS_WINIT(enc) {    \
    #enc, NULL,                         \
    enc##_codec_init,                   \
    _STATELESS_METHODS(enc)             \
},
#define END_CODECS_LIST                                 \
    {"", NULL,} };                                      \
    static const MultibyteCodec *codec_list =           \
        (const MultibyteCodec *)_codec_list;

static PyObject *
getmultibytecodec(void)
{
    static PyObject *cofunc = NULL;

    if (cofunc == NULL) {
        PyObject *mod = PyImport_ImportModuleNoBlock("_multibytecodec");
        if (mod == NULL)
            return NULL;
        cofunc = PyObject_GetAttrString(mod, "__create_codec");
        Py_DECREF(mod);
    }
    return cofunc;
}

static PyObject *
getcodec(PyObject *self, PyObject *encoding)
{
    PyObject *codecobj, *r, *cofunc;
    const MultibyteCodec *codec;
    const char *enc;

    if (!PyString_Check(encoding)) {
        PyErr_SetString(PyExc_TypeError,
                        "encoding name must be a string.");
        return NULL;
    }

    cofunc = getmultibytecodec();
    if (cofunc == NULL)
        return NULL;

    enc = PyString_AS_STRING(encoding);
    for (codec = codec_list; codec->encoding[0]; codec++)
        if (strcmp(codec->encoding, enc) == 0)
            break;

    if (codec->encoding[0] == '\0') {
        PyErr_SetString(PyExc_LookupError,
                        "no such codec is supported.");
        return NULL;
    }

    codecobj = PyCapsule_New((void *)codec, PyMultibyteCodec_CAPSULE_NAME, NULL);
    if (codecobj == NULL)
        return NULL;

    r = PyObject_CallFunctionObjArgs(cofunc, codecobj, NULL);
    Py_DECREF(codecobj);

    return r;
}

static struct PyMethodDef __methods[] = {
    {"getcodec", (PyCFunction)getcodec, METH_O, ""},
    {NULL, NULL},
};

static int
register_maps(PyObject *module)
{
    const struct dbcs_map *h;

    for (h = mapping_list; h->charset[0] != '\0'; h++) {
        char mhname[256] = "__map_";
        int r;
        strcpy(mhname + sizeof("__map_") - 1, h->charset);
        r = PyModule_AddObject(module, mhname,
                        PyCapsule_New((void *)h, PyMultibyteCodec_CAPSULE_NAME, NULL));
        if (r == -1)
            return -1;
    }
    return 0;
}

#ifdef USING_BINARY_PAIR_SEARCH
static DBCHAR
find_pairencmap(ucs2_t body, ucs2_t modifier,
                const struct pair_encodemap *haystack, int haystacksize)
{
    int pos, min, max;
    ucs4_t value = body << 16 | modifier;

    min = 0;
    max = haystacksize;

    for (pos = haystacksize >> 1; min != max; pos = (min + max) >> 1) {
        if (value < haystack[pos].uniseq) {
            if (max != pos) {
                max = pos;
                continue;
            }
        }
        else if (value > haystack[pos].uniseq) {
            if (min != pos) {
                min = pos;
                continue;
            }
        }
        break;
    }

    if (value == haystack[pos].uniseq) {
        return haystack[pos].code;
    }
    return DBCINV;
}
#endif

#ifdef USING_IMPORTED_MAPS
#define IMPORT_MAP(locale, charset, encmap, decmap) \
    importmap("_codecs_" #locale, "__map_" #charset, \
              (const void**)encmap, (const void**)decmap)

static int
importmap(const char *modname, const char *symbol,
          const void **encmap, const void **decmap)
{
    PyObject *o, *mod;

    mod = PyImport_ImportModule((char *)modname);
    if (mod == NULL)
        return -1;

    o = PyObject_GetAttrString(mod, (char*)symbol);
    if (o == NULL)
        goto errorexit;
    else if (!PyCapsule_IsValid(o, PyMultibyteCodec_CAPSULE_NAME)) {
        PyErr_SetString(PyExc_ValueError,
                        "map data must be a Capsule.");
        goto errorexit;
    }
    else {
        struct dbcs_map *map;
        map = PyCapsule_GetPointer(o, PyMultibyteCodec_CAPSULE_NAME);
        if (encmap != NULL)
            *encmap = map->encmap;
        if (decmap != NULL)
            *decmap = map->decmap;
        Py_DECREF(o);
    }

    Py_DECREF(mod);
    return 0;

errorexit:
    Py_DECREF(mod);
    return -1;
}
#endif

#define I_AM_A_MODULE_FOR(loc)                                          \
    void                                                                \
    init_codecs_##loc(void)                                             \
    {                                                                   \
        PyObject *m = Py_InitModule("_codecs_" #loc, __methods);\
        if (m != NULL)                                                  \
            (void)register_maps(m);                                     \
    }

#endif