/*
 * GiST support for ltree
 * Teodor Sigaev <teodor@stack.net>
 * contrib/ltree/ltree_gist.c
 */
#include "postgres.h"
#include "knl/knl_variable.h"

#include "access/gist.h"
#include "access/skey.h"
#include "crc32.h"
#include "ltree.h"

#define NEXTVAL(x) ((lquery*)((char*)(x) + INTALIGN(VARSIZE(x))))

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

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

Datum ltree_gist_in(PG_FUNCTION_ARGS)
{
    ereport(ERROR, (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), errmsg("ltree_gist_in() not implemented")));
    PG_RETURN_DATUM(0);
}

Datum ltree_gist_out(PG_FUNCTION_ARGS)
{
    ereport(ERROR, (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), errmsg("ltree_gist_out() not implemented")));
    PG_RETURN_DATUM(0);
}

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

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

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

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

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

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

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

#define ISEQ(a, b) ((a)->numlevel == (b)->numlevel && ltree_compare(a, b) == 0)
#define GETENTRY(vec, pos) ((ltree_gist*)DatumGetPointer((vec)->vector[(pos)].key))

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

    if (entry->leafkey) { /* ltree */
        ltree_gist* key = NULL;
        ltree* val = (ltree*)DatumGetPointer(PG_DETOAST_DATUM(entry->key));
        int4 len = LTG_HDRSIZE + VARSIZE(val);

        key = (ltree_gist*)palloc(len);
        SET_VARSIZE(key, len);
        key->flag = LTG_ONENODE;
        memcpy((void*)LTG_NODE(key), (void*)val, VARSIZE(val));

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

Datum ltree_decompress(PG_FUNCTION_ARGS)
{
    GISTENTRY* entry = (GISTENTRY*)PG_GETARG_POINTER(0);
    ltree_gist* key = (ltree_gist*)DatumGetPointer(PG_DETOAST_DATUM(entry->key));

    if (PointerGetDatum(key) != entry->key) {
        GISTENTRY* retval = (GISTENTRY*)palloc(sizeof(GISTENTRY));

        gistentryinit(*retval, PointerGetDatum(key), entry->rel, entry->page, entry->offset, FALSE);
        PG_RETURN_POINTER(retval);
    }
    PG_RETURN_POINTER(entry);
}

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

    *result = false;
    if (LTG_ISONENODE(a) != LTG_ISONENODE(b))
        PG_RETURN_POINTER(result);

    if (LTG_ISONENODE(a))
        *result = (ISEQ(LTG_NODE(a), LTG_NODE(b))) ? true : false;
    else {
        int4 i;
        BITVECP sa = LTG_SIGN(a), sb = LTG_SIGN(b);

        if (LTG_ISALLTRUE(a) != LTG_ISALLTRUE(b))
            PG_RETURN_POINTER(result);

        if (!ISEQ(LTG_LNODE(a), LTG_LNODE(b)))
            PG_RETURN_POINTER(result);
        if (!ISEQ(LTG_RNODE(a), LTG_RNODE(b)))
            PG_RETURN_POINTER(result);

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

    PG_RETURN_POINTER(result);
}

static void hashing(BITVECP sign, ltree* t)
{
    int tlen = t->numlevel;
    ltree_level* cur = LTREE_FIRST(t);
    int hash;

    while (tlen > 0) {
        hash = ltree_crc32_sz(cur->name, cur->len);
        HASH(sign, hash);
        cur = LEVEL_NEXT(cur);
        tlen--;
    }
}

Datum ltree_union(PG_FUNCTION_ARGS)
{
    GistEntryVector* entryvec = (GistEntryVector*)PG_GETARG_POINTER(0);
    int* size = (int*)PG_GETARG_POINTER(1);
    BITVEC base;
    int4 i, j;
    ltree_gist *result, *cur;
    ltree *left = NULL, *right = NULL, *curtree;
    bool isalltrue = false;
    bool isleqr = false;

    MemSet((void*)base, 0, sizeof(BITVEC));
    for (j = 0; j < entryvec->n; j++) {
        cur = GETENTRY(entryvec, j);
        if (LTG_ISONENODE(cur)) {
            curtree = LTG_NODE(cur);
            hashing(base, curtree);
            if (!left || ltree_compare(left, curtree) > 0)
                left = curtree;
            if (!right || ltree_compare(right, curtree) < 0)
                right = curtree;
        } else {
            if (isalltrue || LTG_ISALLTRUE(cur))
                isalltrue = true;
            else {
                BITVECP sc = LTG_SIGN(cur);

                LOOPBYTE((unsigned char*)base)[i] |= sc[i];
            }

            curtree = LTG_LNODE(cur);
            if (!left || ltree_compare(left, curtree) > 0)
                left = curtree;
            curtree = LTG_RNODE(cur);
            if (!right || ltree_compare(right, curtree) < 0)
                right = curtree;
        }
    }

    if (isalltrue == false) {
        isalltrue = true;
        LOOPBYTE
        {
            if (((unsigned char*)base)[i] != 0xff) {
                isalltrue = false;
                break;
            }
        }
    }

    isleqr = (left == right || ISEQ(left, right)) ? true : false;
    *size = LTG_HDRSIZE + ((isalltrue) ? 0 : SIGLEN) + VARSIZE(left) + ((isleqr) ? 0 : VARSIZE(right));

    result = (ltree_gist*)palloc(*size);
    SET_VARSIZE(result, *size);
    result->flag = 0;

    if (isalltrue)
        result->flag |= LTG_ALLTRUE;
    else
        memcpy((void*)LTG_SIGN(result), base, SIGLEN);

    memcpy((void*)LTG_LNODE(result), (void*)left, VARSIZE(left));
    if (isleqr)
        result->flag |= LTG_NORIGHT;
    else
        memcpy((void*)LTG_RNODE(result), (void*)right, VARSIZE(right));

    PG_RETURN_POINTER(result);
}

Datum ltree_penalty(PG_FUNCTION_ARGS)
{
    ltree_gist* origval = (ltree_gist*)DatumGetPointer(((GISTENTRY*)PG_GETARG_POINTER(0))->key);
    ltree_gist* newval = (ltree_gist*)DatumGetPointer(((GISTENTRY*)PG_GETARG_POINTER(1))->key);
    float* penalty = (float*)PG_GETARG_POINTER(2);
    int4 cmpr, cmpl;

    cmpl = ltree_compare(LTG_GETLNODE(origval), LTG_GETLNODE(newval));
    cmpr = ltree_compare(LTG_GETRNODE(newval), LTG_GETRNODE(origval));

    *penalty = Max(cmpl, 0) + Max(cmpr, 0);

    PG_RETURN_POINTER(penalty);
}

/* used for sorting */
typedef struct rix {
    int index;
    ltree* r;
} RIX;

static int treekey_cmp(const void* a, const void* b)
{
    return ltree_compare(((const RIX*)a)->r, ((const RIX*)b)->r);
}

Datum ltree_picksplit(PG_FUNCTION_ARGS)
{
    GistEntryVector* entryvec = (GistEntryVector*)PG_GETARG_POINTER(0);
    GIST_SPLITVEC* v = (GIST_SPLITVEC*)PG_GETARG_POINTER(1);
    OffsetNumber j;
    int4 i;
    RIX* array = NULL;
    OffsetNumber maxoff;
    int nbytes;
    int size;
    ltree *lu_l, *lu_r, *ru_l, *ru_r;
    ltree_gist *lu, *ru;
    BITVEC ls, rs;
    bool lisat = false, risat = false, isleqr;

    memset((void*)ls, 0, sizeof(BITVEC));
    memset((void*)rs, 0, sizeof(BITVEC));
    maxoff = entryvec->n - 1;
    nbytes = (maxoff + 2) * sizeof(OffsetNumber);
    v->spl_left = (OffsetNumber*)palloc(nbytes);
    v->spl_right = (OffsetNumber*)palloc(nbytes);
    v->spl_nleft = 0;
    v->spl_nright = 0;
    array = (RIX*)palloc(sizeof(RIX) * (maxoff + 1));

    /* copy the data into RIXes, and sort the RIXes */
    for (j = FirstOffsetNumber; j <= maxoff; j = OffsetNumberNext(j)) {
        array[j].index = j;
        lu = GETENTRY(entryvec, j); /* use as tmp val */
        array[j].r = LTG_GETLNODE(lu);
    }

    qsort((void*)&array[FirstOffsetNumber], maxoff - FirstOffsetNumber + 1, sizeof(RIX), treekey_cmp);

    lu_l = lu_r = ru_l = ru_r = NULL;
    for (j = FirstOffsetNumber; j <= maxoff; j = OffsetNumberNext(j)) {
        lu = GETENTRY(entryvec, array[j].index); /* use as tmp val */
        if (j <= (maxoff - FirstOffsetNumber + 1) / 2) {
            v->spl_left[v->spl_nleft] = array[j].index;
            v->spl_nleft++;
            if (lu_r == NULL || ltree_compare(LTG_GETRNODE(lu), lu_r) > 0)
                lu_r = LTG_GETRNODE(lu);
            if (LTG_ISONENODE(lu))
                hashing(ls, LTG_NODE(lu));
            else {
                if (lisat || LTG_ISALLTRUE(lu))
                    lisat = true;
                else {
                    BITVECP sc = LTG_SIGN(lu);

                    LOOPBYTE((unsigned char*)ls)[i] |= sc[i];
                }
            }
        } else {
            v->spl_right[v->spl_nright] = array[j].index;
            v->spl_nright++;
            if (ru_r == NULL || ltree_compare(LTG_GETRNODE(lu), ru_r) > 0)
                ru_r = LTG_GETRNODE(lu);
            if (LTG_ISONENODE(lu))
                hashing(rs, LTG_NODE(lu));
            else {
                if (risat || LTG_ISALLTRUE(lu))
                    risat = true;
                else {
                    BITVECP sc = LTG_SIGN(lu);

                    LOOPBYTE((unsigned char*)rs)[i] |= sc[i];
                }
            }
        }
    }

    if (lisat == false) {
        lisat = true;
        LOOPBYTE
        {
            if (((unsigned char*)ls)[i] != 0xff) {
                lisat = false;
                break;
            }
        }
    }

    if (risat == false) {
        risat = true;
        LOOPBYTE
        {
            if (((unsigned char*)rs)[i] != 0xff) {
                risat = false;
                break;
            }
        }
    }

    lu_l = LTG_GETLNODE(GETENTRY(entryvec, array[FirstOffsetNumber].index));
    isleqr = (lu_l == lu_r || ISEQ(lu_l, lu_r)) ? true : false;
    size = LTG_HDRSIZE + ((lisat) ? 0 : SIGLEN) + VARSIZE(lu_l) + ((isleqr) ? 0 : VARSIZE(lu_r));
    lu = (ltree_gist*)palloc(size);
    SET_VARSIZE(lu, size);
    lu->flag = 0;
    if (lisat)
        lu->flag |= LTG_ALLTRUE;
    else
        memcpy((void*)LTG_SIGN(lu), ls, SIGLEN);
    memcpy((void*)LTG_LNODE(lu), (void*)lu_l, VARSIZE(lu_l));
    if (isleqr)
        lu->flag |= LTG_NORIGHT;
    else
        memcpy((void*)LTG_RNODE(lu), (void*)lu_r, VARSIZE(lu_r));

    ru_l = LTG_GETLNODE(GETENTRY(entryvec, array[1 + ((maxoff - FirstOffsetNumber + 1) / 2)].index));
    isleqr = (ru_l == ru_r || ISEQ(ru_l, ru_r)) ? true : false;
    size = LTG_HDRSIZE + ((risat) ? 0 : SIGLEN) + VARSIZE(ru_l) + ((isleqr) ? 0 : VARSIZE(ru_r));
    ru = (ltree_gist*)palloc(size);
    SET_VARSIZE(ru, size);
    ru->flag = 0;
    if (risat)
        ru->flag |= LTG_ALLTRUE;
    else
        memcpy((void*)LTG_SIGN(ru), rs, SIGLEN);
    memcpy((void*)LTG_LNODE(ru), (void*)ru_l, VARSIZE(ru_l));
    if (isleqr)
        ru->flag |= LTG_NORIGHT;
    else
        memcpy((void*)LTG_RNODE(ru), (void*)ru_r, VARSIZE(ru_r));

    v->spl_ldatum = PointerGetDatum(lu);
    v->spl_rdatum = PointerGetDatum(ru);

    PG_RETURN_POINTER(v);
}

static bool gist_isparent(ltree_gist* key, ltree* query)
{
    int4 numlevel = query->numlevel;
    int i;

    for (i = query->numlevel; i >= 0; i--) {
        query->numlevel = i;
        if (ltree_compare(query, LTG_GETLNODE(key)) >= 0 && ltree_compare(query, LTG_GETRNODE(key)) <= 0) {
            query->numlevel = numlevel;
            return true;
        }
    }

    query->numlevel = numlevel;
    return false;
}

static ltree* copy_ltree(ltree* src)
{
    ltree* dst = (ltree*)palloc(VARSIZE(src));

    memcpy(dst, src, VARSIZE(src));
    return dst;
}

static bool gist_ischild(ltree_gist* key, ltree* query)
{
    ltree* left = copy_ltree(LTG_GETLNODE(key));
    ltree* right = copy_ltree(LTG_GETRNODE(key));
    bool res = true;

    if (left->numlevel > query->numlevel)
        left->numlevel = query->numlevel;

    if (ltree_compare(query, left) < 0)
        res = false;

    if (right->numlevel > query->numlevel)
        right->numlevel = query->numlevel;

    if (res && ltree_compare(query, right) > 0)
        res = false;

    pfree(left);
    pfree(right);

    return res;
}

static bool gist_qe(ltree_gist* key, lquery* query)
{
    lquery_level* curq = LQUERY_FIRST(query);
    BITVECP sign = LTG_SIGN(key);
    int qlen = query->numlevel;

    if (LTG_ISALLTRUE(key))
        return true;

    while (qlen > 0) {
        if (curq->numvar && LQL_CANLOOKSIGN(curq)) {
            bool isexist = false;
            int vlen = curq->numvar;
            lquery_variant* curv = LQL_FIRST(curq);

            while (vlen > 0) {
                if (GETBIT(sign, HASHVAL(curv->val))) {
                    isexist = true;
                    break;
                }
                curv = LVAR_NEXT(curv);
                vlen--;
            }
            if (!isexist)
                return false;
        }

        curq = LQL_NEXT(curq);
        qlen--;
    }

    return true;
}

static int gist_tqcmp(ltree* t, lquery* q)
{
    ltree_level* al = LTREE_FIRST(t);
    lquery_level* ql = LQUERY_FIRST(q);
    lquery_variant* bl = NULL;
    int an = t->numlevel;
    int bn = q->firstgood;
    int res = 0;

    while (an > 0 && bn > 0) {
        bl = LQL_FIRST(ql);
        if ((res = memcmp(al->name, bl->name, Min(al->len, bl->len))) == 0) {
            if (al->len != bl->len)
                return al->len - bl->len;
        } else
            return res;
        an--;
        bn--;
        al = LEVEL_NEXT(al);
        ql = LQL_NEXT(ql);
    }

    return Min(t->numlevel, q->firstgood) - q->firstgood;
}

static bool gist_between(ltree_gist* key, lquery* query)
{
    if (query->firstgood == 0)
        return true;

    if (gist_tqcmp(LTG_GETLNODE(key), query) > 0)
        return false;

    if (gist_tqcmp(LTG_GETRNODE(key), query) < 0)
        return false;

    return true;
}

static bool checkcondition_bit(void* checkval, ITEM* val)
{
    return (FLG_CANLOOKSIGN(val->flag)) ? GETBIT(checkval, HASHVAL(val->val)) : true;
}

static bool gist_qtxt(ltree_gist* key, ltxtquery* query)
{
    if (LTG_ISALLTRUE(key))
        return true;

    return ltree_execute(GETQUERY(query), (void*)LTG_SIGN(key), false, checkcondition_bit);
}

static bool arrq_cons(ltree_gist* key, ArrayType* _query)
{
    lquery* query = (lquery*)ARR_DATA_PTR(_query);
    int num = ArrayGetNItems(ARR_NDIM(_query), ARR_DIMS(_query));

    if (ARR_NDIM(_query) > 1)
        ereport(ERROR, (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR), errmsg("array must be one-dimensional")));
    if (array_contains_nulls(_query))
        ereport(ERROR, (errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED), errmsg("array must not contain nulls")));

    while (num > 0) {
        if (gist_qe(key, query) && gist_between(key, query))
            return true;
        num--;
        query = NEXTVAL(query);
    }
    return false;
}

Datum ltree_consistent(PG_FUNCTION_ARGS)
{
    GISTENTRY* entry = (GISTENTRY*)PG_GETARG_POINTER(0);
    StrategyNumber strategy = (StrategyNumber)PG_GETARG_UINT16(2);

    bool* recheck = (bool*)PG_GETARG_POINTER(4);
    ltree_gist* key = (ltree_gist*)DatumGetPointer(entry->key);
    void* query = NULL;
    bool res = false;

    /* All cases served by this function are exact */
    *recheck = false;

    switch (strategy) {
        case BTLessStrategyNumber:
            query = PG_GETARG_LTREE(1);
            res = (GIST_LEAF(entry)) ? (ltree_compare((ltree*)query, LTG_NODE(key)) > 0)
                                     : (ltree_compare((ltree*)query, LTG_GETLNODE(key)) >= 0);
            break;
        case BTLessEqualStrategyNumber:
            query = PG_GETARG_LTREE(1);
            res = (ltree_compare((ltree*)query, LTG_GETLNODE(key)) >= 0);
            break;
        case BTEqualStrategyNumber:
            query = PG_GETARG_LTREE(1);
            if (GIST_LEAF(entry))
                res = (ltree_compare((ltree*)query, LTG_NODE(key)) == 0);
            else
                res = (ltree_compare((ltree*)query, LTG_GETLNODE(key)) >= 0 &&
                       ltree_compare((ltree*)query, LTG_GETRNODE(key)) <= 0);
            break;
        case BTGreaterEqualStrategyNumber:
            query = PG_GETARG_LTREE(1);
            res = (ltree_compare((ltree*)query, LTG_GETRNODE(key)) <= 0);
            break;
        case BTGreaterStrategyNumber:
            query = PG_GETARG_LTREE(1);
            res = (GIST_LEAF(entry)) ? (ltree_compare((ltree*)query, LTG_GETRNODE(key)) < 0)
                                     : (ltree_compare((ltree*)query, LTG_GETRNODE(key)) <= 0);
            break;
        case 10:
            query = PG_GETARG_LTREE_COPY(1);
            res = (GIST_LEAF(entry)) ? inner_isparent((ltree*)query, LTG_NODE(key)) : gist_isparent(key, (ltree*)query);
            break;
        case 11:
            query = PG_GETARG_LTREE(1);
            res = (GIST_LEAF(entry)) ? inner_isparent(LTG_NODE(key), (ltree*)query) : gist_ischild(key, (ltree*)query);
            break;
        case 12:
        case 13:
            query = PG_GETARG_LQUERY(1);
            if (GIST_LEAF(entry))
                res = DatumGetBool(
                    DirectFunctionCall2(ltq_regex, PointerGetDatum(LTG_NODE(key)), PointerGetDatum((lquery*)query)));
            else
                res = (gist_qe(key, (lquery*)query) && gist_between(key, (lquery*)query));
            break;
        case 14:
        case 15:
            query = PG_GETARG_LQUERY(1);
            if (GIST_LEAF(entry))
                res = DatumGetBool(
                    DirectFunctionCall2(ltxtq_exec, PointerGetDatum(LTG_NODE(key)), PointerGetDatum((lquery*)query)));
            else
                res = gist_qtxt(key, (ltxtquery*)query);
            break;
        case 16:
        case 17:
            query = DatumGetPointer(PG_DETOAST_DATUM(PG_GETARG_DATUM(1)));
            if (GIST_LEAF(entry))
                res = DatumGetBool(DirectFunctionCall2(
                    lt_q_regex, PointerGetDatum(LTG_NODE(key)), PointerGetDatum((ArrayType*)query)));
            else
                res = arrq_cons(key, (ArrayType*)query);
            break;
        default:
            /* internal error */
            elog(ERROR, "unrecognized StrategyNumber: %d", strategy);
    }

    PG_FREE_IF_COPY(query, 1);
    PG_RETURN_BOOL(res);
}