/*
 * contrib/hstore/hstore_gist.c
 */
#include "postgres.h"
#include "knl/knl_variable.h"

#include "access/gist.h"
#include "access/skey.h"
#include "catalog/pg_type.h"

#include "crc32.h"
#include "hstore.h"

/* bigint defines */
#define BITBYTE 8
#define SIGLENINT 4 /* >122 => key will toast, so very slow!!! */
#define SIGLEN (sizeof(int) * SIGLENINT)
#define SIGLENBIT (SIGLEN * BITBYTE)

typedef char BITVEC[SIGLEN];
typedef char* BITVECP;

#define SIGPTR(x) ((BITVECP)ARR_DATA_PTR(x))

#define LOOPBYTE for (i = 0; i < SIGLEN; i++)

#define LOOPBIT for (i = 0; i < SIGLENBIT; i++)

/* beware of multiple evaluation of arguments to these macros! */
#define GETBYTE(x, i) (*((BITVECP)(x) + (int)((i) / BITBYTE)))
#define GETBITBYTE(x, i) ((*((char*)(x)) >> (i)) & 0x01)
#define CLRBIT(x, i) GETBYTE(x, i) &= ~(0x01 << ((i) % BITBYTE))
#define SETBIT(x, i) GETBYTE(x, i) |= (0x01 << ((i) % BITBYTE))
#define GETBIT(x, i) ((GETBYTE(x, i) >> ((i) % BITBYTE)) & 0x01)
#define HASHVAL(val) (((unsigned int)(val)) % SIGLENBIT)
#define HASH(sign, val) SETBIT((sign), HASHVAL(val))

typedef struct {
    int32 vl_len_; /* varlena header (do not touch directly!) */
    int4 flag;
    char data[1];
} GISTTYPE;

#define ALLISTRUE 0x04

#define ISALLTRUE(x) (((GISTTYPE*)x)->flag & ALLISTRUE)

#define GTHDRSIZE (VARHDRSZ + sizeof(int4))
#define CALCGTSIZE(flag) (GTHDRSIZE + (((flag)&ALLISTRUE) ? 0 : SIGLEN))

#define GETSIGN(x) ((BITVECP)((char*)x + GTHDRSIZE))

#define SUMBIT(val)                                                                              \
    (GETBITBYTE((val), 0) + GETBITBYTE((val), 1) + GETBITBYTE((val), 2) + GETBITBYTE((val), 3) + \
        GETBITBYTE((val), 4) + GETBITBYTE((val), 5) + GETBITBYTE((val), 6) + GETBITBYTE((val), 7))

#define GETENTRY(vec, pos) ((GISTTYPE*)DatumGetPointer((vec)->vector[(pos)].key))

#define WISH_F(a, b, c) (double)(-(double)(((a) - (b)) * ((a) - (b)) * ((a) - (b))) * (c))

PG_FUNCTION_INFO_V1(ghstore_in);
extern "C" Datum ghstore_in(PG_FUNCTION_ARGS);

PG_FUNCTION_INFO_V1(ghstore_out);
extern "C" Datum ghstore_out(PG_FUNCTION_ARGS);

Datum ghstore_in(PG_FUNCTION_ARGS)
{
    elog(ERROR, "Not implemented");
    PG_RETURN_DATUM(0);
}

Datum ghstore_out(PG_FUNCTION_ARGS)
{
    elog(ERROR, "Not implemented");
    PG_RETURN_DATUM(0);
}

PG_FUNCTION_INFO_V1(ghstore_consistent);
PG_FUNCTION_INFO_V1(ghstore_compress);
PG_FUNCTION_INFO_V1(ghstore_decompress);
PG_FUNCTION_INFO_V1(ghstore_penalty);
PG_FUNCTION_INFO_V1(ghstore_picksplit);
PG_FUNCTION_INFO_V1(ghstore_union);
PG_FUNCTION_INFO_V1(ghstore_same);

extern "C" Datum ghstore_consistent(PG_FUNCTION_ARGS);
extern "C" Datum ghstore_compress(PG_FUNCTION_ARGS);
extern "C" Datum ghstore_decompress(PG_FUNCTION_ARGS);
extern "C" Datum ghstore_penalty(PG_FUNCTION_ARGS);
extern "C" Datum ghstore_picksplit(PG_FUNCTION_ARGS);
extern "C" Datum ghstore_union(PG_FUNCTION_ARGS);
extern "C" Datum ghstore_same(PG_FUNCTION_ARGS);

Datum ghstore_compress(PG_FUNCTION_ARGS)
{
    GISTENTRY* entry = (GISTENTRY*)PG_GETARG_POINTER(0);
    GISTENTRY* retval = entry;

    if (entry->leafkey) {
        GISTTYPE* res = (GISTTYPE*)palloc0(CALCGTSIZE(0));
        HStore* val = DatumGetHStoreP(entry->key);
        NOT_NULL_HS(val);
        HEntry* hsent = ARRPTR(val);
        char* ptr = STRPTR(val);
        int count = HS_COUNT(val);
        int i;

        SET_VARSIZE(res, CALCGTSIZE(0));

        for (i = 0; i < count; ++i) {
            int h;

            h = crc32_sz((char*)HS_KEY(hsent, ptr, i), HS_KEYLEN(hsent, i));
            HASH(GETSIGN(res), h);
            if (!HS_VALISNULL(hsent, i)) {
                h = crc32_sz((char*)HS_VAL(hsent, ptr, i), HS_VALLEN(hsent, i));
                HASH(GETSIGN(res), h);
            }
        }

        retval = (GISTENTRY*)palloc(sizeof(GISTENTRY));
        gistentryinit(*retval, PointerGetDatum(res), entry->rel, entry->page, entry->offset, FALSE);
    } else if (!ISALLTRUE(DatumGetPointer(entry->key))) {
        uint32 i;
        GISTTYPE* res = NULL;
        BITVECP sign = GETSIGN(DatumGetPointer(entry->key));

        LOOPBYTE
        {
            if ((sign[i] & 0xff) != 0xff)
                PG_RETURN_POINTER(retval);
        }

        res = (GISTTYPE*)palloc(CALCGTSIZE(ALLISTRUE));
        SET_VARSIZE(res, CALCGTSIZE(ALLISTRUE));
        res->flag = ALLISTRUE;

        retval = (GISTENTRY*)palloc(sizeof(GISTENTRY));
        gistentryinit(*retval, PointerGetDatum(res), entry->rel, entry->page, entry->offset, FALSE);
    }

    PG_RETURN_POINTER(retval);
}

/*
 * Since type ghstore isn't toastable (and doesn't need to be),
 * this function can be a no-op.
 */
Datum ghstore_decompress(PG_FUNCTION_ARGS)
{
    PG_RETURN_POINTER(PG_GETARG_POINTER(0));
}

Datum ghstore_same(PG_FUNCTION_ARGS)
{
    GISTTYPE* a = (GISTTYPE*)PG_GETARG_POINTER(0);
    GISTTYPE* b = (GISTTYPE*)PG_GETARG_POINTER(1);
    bool* result = (bool*)PG_GETARG_POINTER(2);

    if (ISALLTRUE(a) && ISALLTRUE(b))
        *result = true;
    else if (ISALLTRUE(a))
        *result = false;
    else if (ISALLTRUE(b))
        *result = false;
    else {
        uint32 i;
        BITVECP sa = GETSIGN(a), sb = GETSIGN(b);

        *result = true;
        LOOPBYTE
        {
            if (sa[i] != sb[i]) {
                *result = false;
                break;
            }
        }
    }
    PG_RETURN_POINTER(result);
}

static int4 sizebitvec(BITVECP sign)
{
    int4 size = 0;
    uint32 i;

    LOOPBYTE
    {
        size += SUMBIT(sign);
        sign = (BITVECP)(((char*)sign) + 1);
    }
    return size;
}

static int hemdistsign(BITVECP a, BITVECP b)
{
    uint32 i;
    int dist = 0;

    LOOPBIT
    {
        if (GETBIT(a, i) != GETBIT(b, i))
            dist++;
    }
    return dist;
}

static int hemdist(GISTTYPE* a, GISTTYPE* b)
{
    if (ISALLTRUE(a)) {
        if (ISALLTRUE(b))
            return 0;
        else
            return SIGLENBIT - sizebitvec(GETSIGN(b));
    } else if (ISALLTRUE(b))
        return SIGLENBIT - sizebitvec(GETSIGN(a));

    return hemdistsign(GETSIGN(a), GETSIGN(b));
}

static int4 unionkey(BITVECP sbase, GISTTYPE* add)
{
    uint32 i;
    BITVECP sadd = GETSIGN(add);

    if (ISALLTRUE(add))
        return 1;
    LOOPBYTE
    sbase[i] |= sadd[i];
    return 0;
}

Datum ghstore_union(PG_FUNCTION_ARGS)
{
    GistEntryVector* entryvec = (GistEntryVector*)PG_GETARG_POINTER(0);
    int4 len = entryvec->n;

    int* size = (int*)PG_GETARG_POINTER(1);
    BITVEC base;
    int4 i;
    int4 flag = 0;
    GISTTYPE* result = NULL;
    errno_t rc;

    rc = memset_s((void*)base, sizeof(BITVEC), 0, sizeof(BITVEC));
    securec_check(rc, "\0", "\0");
    for (i = 0; i < len; i++) {
        if (unionkey(base, GETENTRY(entryvec, i))) {
            flag = ALLISTRUE;
            break;
        }
    }

    len = CALCGTSIZE(flag);
    result = (GISTTYPE*)palloc(len);
    SET_VARSIZE(result, len);
    result->flag = flag;
    if (!ISALLTRUE(result)) {
        rc = memcpy_s((void*)GETSIGN(result), len, (void*)base, sizeof(BITVEC));
        securec_check(rc, "\0", "\0");
    }
    *size = len;

    PG_RETURN_POINTER(result);
}

Datum ghstore_penalty(PG_FUNCTION_ARGS)
{
    GISTENTRY* origentry = (GISTENTRY*)PG_GETARG_POINTER(0); /* always ISSIGNKEY */
    GISTENTRY* newentry = (GISTENTRY*)PG_GETARG_POINTER(1);
    float* penalty = (float*)PG_GETARG_POINTER(2);
    GISTTYPE* origval = (GISTTYPE*)DatumGetPointer(origentry->key);
    GISTTYPE* newval = (GISTTYPE*)DatumGetPointer(newentry->key);

    *penalty = hemdist(origval, newval);
    PG_RETURN_POINTER(penalty);
}

typedef struct {
    OffsetNumber pos;
    int4 cost;
} SPLITCOST;

static int comparecost(const void* a, const void* b)
{
    return ((const SPLITCOST*)a)->cost - ((const SPLITCOST*)b)->cost;
}

Datum ghstore_picksplit(PG_FUNCTION_ARGS)
{
    GistEntryVector* entryvec = (GistEntryVector*)PG_GETARG_POINTER(0);
    OffsetNumber maxoff = entryvec->n - 2;

    GIST_SPLITVEC* v = (GIST_SPLITVEC*)PG_GETARG_POINTER(1);
    OffsetNumber k, j;
    GISTTYPE* datum_l = NULL;
    GISTTYPE* datum_r = NULL;
    BITVECP union_l = NULL, union_r = NULL;
    int4 size_alpha, size_beta;
    int4 size_waste, waste = -1;
    int4 nbytes;
    OffsetNumber seed_1 = 0, seed_2 = 0;
    OffsetNumber *left = NULL, *right = NULL;
    BITVECP ptr = NULL;
    uint32 i;
    SPLITCOST* costvector = NULL;
    GISTTYPE* _k = NULL;
    GISTTYPE* _j = NULL;

    nbytes = (maxoff + 2) * sizeof(OffsetNumber);
    v->spl_left = (OffsetNumber*)palloc(nbytes);
    v->spl_right = (OffsetNumber*)palloc(nbytes);

    for (k = FirstOffsetNumber; k < maxoff; k = OffsetNumberNext(k)) {
        _k = GETENTRY(entryvec, k);
        for (j = OffsetNumberNext(k); j <= maxoff; j = OffsetNumberNext(j)) {
            size_waste = hemdist(_k, GETENTRY(entryvec, j));
            if (size_waste > waste) {
                waste = size_waste;
                seed_1 = k;
                seed_2 = j;
            }
        }
    }

    left = v->spl_left;
    v->spl_nleft = 0;
    right = v->spl_right;
    v->spl_nright = 0;

    if (seed_1 == 0 || seed_2 == 0) {
        seed_1 = 1;
        seed_2 = 2;
    }

    /* form initial .. */
    if (ISALLTRUE(GETENTRY(entryvec, seed_1))) {
        datum_l = (GISTTYPE*)palloc(GTHDRSIZE);
        SET_VARSIZE(datum_l, GTHDRSIZE);
        datum_l->flag = ALLISTRUE;
    } else {
        datum_l = (GISTTYPE*)palloc(GTHDRSIZE + SIGLEN);
        SET_VARSIZE(datum_l, GTHDRSIZE + SIGLEN);
        datum_l->flag = 0;
        errno_t rc = memcpy_s(
            (void*)GETSIGN(datum_l), GTHDRSIZE + SIGLEN, (void*)GETSIGN(GETENTRY(entryvec, seed_1)), sizeof(BITVEC));
        securec_check(rc, "\0", "\0");
    }
    if (ISALLTRUE(GETENTRY(entryvec, seed_2))) {
        datum_r = (GISTTYPE*)palloc(GTHDRSIZE);
        SET_VARSIZE(datum_r, GTHDRSIZE);
        datum_r->flag = ALLISTRUE;
    } else {
        datum_r = (GISTTYPE*)palloc(GTHDRSIZE + SIGLEN);
        SET_VARSIZE(datum_r, GTHDRSIZE + SIGLEN);
        datum_r->flag = 0;
        errno_t rc = memcpy_s(
            (void*)GETSIGN(datum_r), GTHDRSIZE + SIGLEN, (void*)GETSIGN(GETENTRY(entryvec, seed_2)), sizeof(BITVEC));
        securec_check(rc, "\0", "\0");
    }

    maxoff = OffsetNumberNext(maxoff);
    /* sort before ... */
    costvector = (SPLITCOST*)palloc(sizeof(SPLITCOST) * maxoff);
    for (j = FirstOffsetNumber; j <= maxoff; j = OffsetNumberNext(j)) {
        costvector[j - 1].pos = j;
        _j = GETENTRY(entryvec, j);
        size_alpha = hemdist(datum_l, _j);
        size_beta = hemdist(datum_r, _j);
        costvector[j - 1].cost = abs(size_alpha - size_beta);
    }
    qsort((void*)costvector, maxoff, sizeof(SPLITCOST), comparecost);

    union_l = GETSIGN(datum_l);
    union_r = GETSIGN(datum_r);

    for (k = 0; k < maxoff; k++) {
        j = costvector[k].pos;
        if (j == seed_1) {
            *left++ = j;
            v->spl_nleft++;
            continue;
        } else if (j == seed_2) {
            *right++ = j;
            v->spl_nright++;
            continue;
        }
        _j = GETENTRY(entryvec, j);
        size_alpha = hemdist(datum_l, _j);
        size_beta = hemdist(datum_r, _j);

        if (size_alpha < size_beta + WISH_F(v->spl_nleft, v->spl_nright, 0.0001)) {
            if (ISALLTRUE(datum_l) || ISALLTRUE(_j)) {
                if (!ISALLTRUE(datum_l)) {
                    errno_t rc = memset_s((void*)union_l, sizeof(BITVEC), 0xff, sizeof(BITVEC));
                    securec_check(rc, "\0", "\0");
                }
            } else {
                ptr = GETSIGN(_j);
                LOOPBYTE
                union_l[i] |= ptr[i];
            }
            *left++ = j;
            v->spl_nleft++;
        } else {
            if (ISALLTRUE(datum_r) || ISALLTRUE(_j)) {
                if (!ISALLTRUE(datum_r)) {
                    errno_t rc = memset_s((void*)union_r, sizeof(BITVEC), 0xff, sizeof(BITVEC));
                    securec_check(rc, "", "");
                }
            } else {
                ptr = GETSIGN(_j);
                LOOPBYTE
                union_r[i] |= ptr[i];
            }
            *right++ = j;
            v->spl_nright++;
        }
    }

    *right = *left = FirstOffsetNumber;

    v->spl_ldatum = PointerGetDatum(datum_l);
    v->spl_rdatum = PointerGetDatum(datum_r);

    PG_RETURN_POINTER(v);
}

Datum ghstore_consistent(PG_FUNCTION_ARGS)
{
    GISTTYPE* entry = (GISTTYPE*)DatumGetPointer(((GISTENTRY*)PG_GETARG_POINTER(0))->key);
    StrategyNumber strategy = (StrategyNumber)PG_GETARG_UINT16(2);

    bool* recheck = (bool*)PG_GETARG_POINTER(4);
    bool res = true;
    BITVECP sign = NULL;

    /* All cases served by this function are inexact */
    *recheck = true;

    if (ISALLTRUE(entry))
        PG_RETURN_BOOL(true);

    sign = GETSIGN(entry);

    if (strategy == HStoreContainsStrategyNumber || strategy == HStoreOldContainsStrategyNumber) {
        HStore* query = PG_GETARG_HS(1);
        NOT_NULL_HS(query);
        HEntry* qe = ARRPTR(query);
        char* qv = STRPTR(query);
        int count = HS_COUNT(query);
        int i;

        for (i = 0; res && i < count; ++i) {
            int crc = crc32_sz((char*)HS_KEY(qe, qv, i), HS_KEYLEN(qe, i));

            if (GETBIT(sign, HASHVAL(crc))) {
                if (!HS_VALISNULL(qe, i)) {
                    crc = crc32_sz((char*)HS_VAL(qe, qv, i), HS_VALLEN(qe, i));
                    if (!GETBIT(sign, HASHVAL(crc)))
                        res = false;
                }
            } else
                res = false;
        }
    } else if (strategy == HStoreExistsStrategyNumber) {
        text* query = PG_GETARG_TEXT_PP(1);
        int crc = crc32_sz(VARDATA_ANY(query), VARSIZE_ANY_EXHDR(query));

        res = (GETBIT(sign, HASHVAL(crc))) ? true : false;
    } else if (strategy == HStoreExistsAllStrategyNumber) {
        ArrayType* query = PG_GETARG_ARRAYTYPE_P(1);
        Datum* key_datums = NULL;
        bool* key_nulls = NULL;
        int key_count;
        int i;

        deconstruct_array(query, TEXTOID, -1, false, 'i', &key_datums, &key_nulls, &key_count);

        for (i = 0; res && i < key_count; ++i) {
            int crc;

            if (key_nulls[i])
                continue;
            crc = crc32_sz(VARDATA(key_datums[i]), VARSIZE(key_datums[i]) - VARHDRSZ);
            if (!(GETBIT(sign, HASHVAL(crc))))
                res = FALSE;
        }
    } else if (strategy == HStoreExistsAnyStrategyNumber) {
        ArrayType* query = PG_GETARG_ARRAYTYPE_P(1);
        Datum* key_datums = NULL;
        bool* key_nulls = NULL;
        int key_count;
        int i;

        deconstruct_array(query, TEXTOID, -1, false, 'i', &key_datums, &key_nulls, &key_count);

        res = FALSE;

        for (i = 0; !res && i < key_count; ++i) {
            int crc;

            if (key_nulls[i])
                continue;
            crc = crc32_sz(VARDATA(key_datums[i]), VARSIZE(key_datums[i]) - VARHDRSZ);
            if (GETBIT(sign, HASHVAL(crc)))
                res = TRUE;
        }
    } else
        elog(ERROR, "Unsupported strategy number: %d", strategy);

    PG_RETURN_BOOL(res);
}