/*
 * 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 Py_UCS4 *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 {
    Py_UCS4 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,                \
        int kind, const void *data,                                     \
        Py_ssize_t *inpos, Py_ssize_t inlen,                            \
        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,                 \
        _PyUnicodeWriter *writer)
#define DECODER_RESET(encoding)                                         \
    static Py_ssize_t encoding##_decode_reset(                          \
        MultibyteCodec_State *state, const void *config)

#define NEXT_IN(i)                              \
    do {                                        \
        (*inbuf) += (i);                        \
        (inleft) -= (i);                        \
    } while (0)
#define NEXT_INCHAR(i)                          \
    do {                                        \
        (*inpos) += (i);                        \
    } while (0)
#define NEXT_OUT(o)                             \
    do {                                        \
        (*outbuf) += (o);                       \
        (outleft) -= (o);                       \
    } while (0)
#define NEXT(i, o)                              \
    do {                                        \
        NEXT_INCHAR(i);                         \
        NEXT_OUT(o);                            \
    } while (0)

#define REQUIRE_INBUF(n)                        \
    do {                                        \
        if (inleft < (n))                       \
            return MBERR_TOOFEW;                \
    } while (0)

#define REQUIRE_OUTBUF(n)                       \
    do {                                        \
        if (outleft < (n))                      \
            return MBERR_TOOSMALL;              \
    } while (0)

#define INBYTE1 ((*inbuf)[0])
#define INBYTE2 ((*inbuf)[1])
#define INBYTE3 ((*inbuf)[2])
#define INBYTE4 ((*inbuf)[3])

#define INCHAR1 (PyUnicode_READ(kind, data, *inpos))
#define INCHAR2 (PyUnicode_READ(kind, data, *inpos + 1))

#define OUTCHAR(c)                                                         \
    do {                                                                   \
        if (_PyUnicodeWriter_WriteChar(writer, (c)) < 0)                   \
            return MBERR_EXCEPTION;                                         \
    } while (0)

#define OUTCHAR2(c1, c2)                                                   \
    do {                                                                   \
        Py_UCS4 _c1 = (c1);                                                \
        Py_UCS4 _c2 = (c2);                                                \
        if (_PyUnicodeWriter_Prepare(writer, 2, Py_MAX(_c1, c2)) < 0)      \
            return MBERR_EXCEPTION;                                        \
        PyUnicode_WRITE(writer->kind, writer->data, writer->pos, _c1);     \
        PyUnicode_WRITE(writer->kind, writer->data, writer->pos + 1, _c2); \
        writer->pos += 2;                                                  \
    } while (0)

#define OUTBYTEI(c, i)                     \
    do {                                   \
        assert((unsigned char)(c) == (c)); \
        ((*outbuf)[i]) = (c);              \
    } while (0)

#define OUTBYTE1(c) OUTBYTEI(c, 0)
#define OUTBYTE2(c) OUTBYTEI(c, 1)
#define OUTBYTE3(c) OUTBYTEI(c, 2)
#define OUTBYTE4(c) OUTBYTEI(c, 3)

#define WRITEBYTE1(c1)              \
    do {                            \
        REQUIRE_OUTBUF(1);          \
        OUTBYTE1(c1);               \
    } while (0)
#define WRITEBYTE2(c1, c2)          \
    do {                            \
        REQUIRE_OUTBUF(2);          \
        OUTBYTE1(c1);               \
        OUTBYTE2(c2);               \
    } while (0)
#define WRITEBYTE3(c1, c2, c3)      \
    do {                            \
        REQUIRE_OUTBUF(3);          \
        OUTBYTE1(c1);               \
        OUTBYTE2(c2);               \
        OUTBYTE3(c3);               \
    } while (0)
#define WRITEBYTE4(c1, c2, c3, c4)  \
    do {                            \
        REQUIRE_OUTBUF(4);          \
        OUTBYTE1(c1);               \
        OUTBYTE2(c2);               \
        OUTBYTE3(c3);               \
        OUTBYTE4(c4);               \
    } while (0)

#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(charset, assi, uni)                     \
    _TRYMAP_ENC(&charset##_encmap[(uni) >> 8], assi, (uni) & 0xff)

#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)                     \
    _TRYMAP_DEC(&charset##_decmap[c1], assi, c2)

#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)
{
    PyObject *mod = PyImport_ImportModuleNoBlock("_multibytecodec");
    if (mod == NULL) {
        return NULL;
    }

    PyObject *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 (!PyUnicode_Check(encoding)) {
        PyErr_SetString(PyExc_TypeError,
                        "encoding name must be a string.");
        return NULL;
    }
    enc = PyUnicode_AsUTF8(encoding);
    if (enc == NULL)
        return NULL;

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

    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_CallOneArg(cofunc, codecobj);
    Py_DECREF(codecobj);
    Py_DECREF(cofunc);

    return r;
}


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

    for (h = mapping_list; h->charset[0] != '\0'; h++) {
        char mhname[256] = "__map_";
        strcpy(mhname + sizeof("__map_") - 1, h->charset);

        PyObject *capsule = PyCapsule_New((void *)h,
                                          PyMultibyteCodec_CAPSULE_NAME, NULL);
        if (capsule == NULL) {
            return -1;
        }
        if (PyModule_AddObject(module, mhname, capsule) < 0) {
            Py_DECREF(capsule);
            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;
    Py_UCS4 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(modname);
    if (mod == NULL)
        return -1;

    o = PyObject_GetAttrString(mod, 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

static int
_cjk_exec(PyObject *module)
{
    return register_maps(module);
}


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

static PyModuleDef_Slot _cjk_slots[] = {
    {Py_mod_exec, _cjk_exec},
    {0, NULL}
};

#define I_AM_A_MODULE_FOR(loc)                                          \
    static struct PyModuleDef _cjk_module = {                           \
        PyModuleDef_HEAD_INIT,                                          \
        .m_name = "_codecs_"#loc,                                       \
        .m_size = 0,                                                    \
        .m_methods = _cjk_methods,                                      \
        .m_slots = _cjk_slots,                                          \
    };                                                                  \
                                                                        \
    PyMODINIT_FUNC                                                      \
    PyInit__codecs_##loc(void)                                          \
    {                                                                   \
        return PyModuleDef_Init(&_cjk_module);                          \
    }

#endif