/*
 * GiST support for ltree[]
 * Teodor Sigaev <teodor@stack.net>
 */

#include "ltree.h"
#include "access/gist.h"
#include "access/rtree.h"
#include "access/nbtree.h"
#include "utils/array.h"

#include "crc32.h"

PG_FUNCTION_INFO_V1(_ltree_compress);
Datum		_ltree_compress(PG_FUNCTION_ARGS);

PG_FUNCTION_INFO_V1(_ltree_same);
Datum		_ltree_same(PG_FUNCTION_ARGS);

PG_FUNCTION_INFO_V1(_ltree_union);
Datum		_ltree_union(PG_FUNCTION_ARGS);

PG_FUNCTION_INFO_V1(_ltree_penalty);
Datum		_ltree_penalty(PG_FUNCTION_ARGS);

PG_FUNCTION_INFO_V1(_ltree_picksplit);
Datum		_ltree_picksplit(PG_FUNCTION_ARGS);

PG_FUNCTION_INFO_V1(_ltree_consistent);
Datum		_ltree_consistent(PG_FUNCTION_ARGS);

#define GETENTRY(vec,pos) ((ltree_gist *) DatumGetPointer(((GISTENTRY *) VARDATA(vec))[(pos)].key))
#define NEXTVAL(x) ( (ltree*)( (char*)(x) + INTALIGN( VARSIZE(x) ) ) )
#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 WISH_F(a,b,c) (double)( -(double)(((a)-(b))*((a)-(b))*((a)-(b)))*(c) )

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);
		AHASH(sign, hash);
		cur = LEVEL_NEXT(cur);
		tlen--;
	}
}

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

	if (entry->leafkey)
	{							/* ltree */
		ltree_gist *key;
		ArrayType  *val = DatumGetArrayTypeP(entry->key);
		int4		len = LTG_HDRSIZE + ASIGLEN;
		int			num = ArrayGetNItems(ARR_NDIM(val), ARR_DIMS(val));
		ltree	   *item = (ltree *) ARR_DATA_PTR(val);

		if (ARR_NDIM(val) != 1)
			elog(ERROR, "Dimension of array != 1");

		key = (ltree_gist *) palloc(len);
		key->len = len;
		key->flag = 0;

		MemSet(LTG_SIGN(key), 0, sizeof(ASIGLEN));
		while (num > 0)
		{
			hashing(LTG_SIGN(key), item);
			num--;
			item = NEXTVAL(item);
		}

		if (PointerGetDatum(val) != entry->key)
			pfree(val);

		retval = (GISTENTRY *) palloc(sizeof(GISTENTRY));
		gistentryinit(*retval, PointerGetDatum(key),
					  entry->rel, entry->page,
					  entry->offset, key->len, FALSE);
	}
	else if ( !LTG_ISALLTRUE(entry->key) ) 
	{
		int4		i,
					len;
		ltree_gist *key;

		BITVECP		sign = LTG_SIGN(DatumGetPointer(entry->key));

		ALOOPBYTE(
				  if ((sign[i]&0xff) != 0xff)
				  PG_RETURN_POINTER(retval);
		);
		len = LTG_HDRSIZE;
		key = (ltree_gist *) palloc(len);
		key->len = len;
		key->flag = LTG_ALLTRUE;

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

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);

	if (LTG_ISALLTRUE(a) && LTG_ISALLTRUE(b))
		*result = true;
	else if (LTG_ISALLTRUE(a))
		*result = false;
	else if (LTG_ISALLTRUE(b))
		*result = false;
	else
	{
		int4		i;
		BITVECP		sa = LTG_SIGN(a),
					sb = LTG_SIGN(b);

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

static int4
unionkey(BITVECP sbase, ltree_gist * add)
{
	int4		i;
	BITVECP		sadd = LTG_SIGN(add);

	if (LTG_ISALLTRUE(add))
		return 1;

	ALOOPBYTE(
			  sbase[i] |= sadd[i];
	);
	return 0;
}

Datum
_ltree_union(PG_FUNCTION_ARGS)
{
	bytea	   *entryvec = (bytea *) PG_GETARG_POINTER(0);
	int		   *size = (int *) PG_GETARG_POINTER(1);
	ABITVEC		base;
	int4		len = (VARSIZE(entryvec) - VARHDRSZ) / sizeof(GISTENTRY);
	int4		i;
	int4		flag = 0;
	ltree_gist *result;

	MemSet((void *) base, 0, sizeof(ABITVEC));
	for (i = 0; i < len; i++)
	{
		if (unionkey(base, GETENTRY(entryvec, i)))
		{
			flag = LTG_ALLTRUE;
			break;
		}
	}

	len = LTG_HDRSIZE + ((flag & LTG_ALLTRUE) ? 0 : ASIGLEN);
	result = (ltree_gist *) palloc(len);
	*size = result->len = len;
	result->flag = flag;
	if (!LTG_ISALLTRUE(result))
		memcpy((void *) LTG_SIGN(result), (void *) base, sizeof(ABITVEC));

	PG_RETURN_POINTER(result);
}

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

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

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);
	BITVECP		orig = LTG_SIGN(origval);

	if (LTG_ISALLTRUE(origval))
	{
		*penalty = 0.1;
		PG_RETURN_POINTER(penalty);
	}

	if (LTG_ISALLTRUE(newval))
		*penalty = (float) (ASIGLENBIT - sizebitvec(orig));
	else
	{
		unsigned char valtmp;
		BITVECP		nval = LTG_SIGN(newval);
		int4		i,
					unionsize = 0;

		ALOOPBYTE(
				  valtmp = nval[i] | orig[i];
		unionsize += SUMBIT(valtmp) - SUMBIT(orig[i]);
		);
		*penalty = (float) unionsize;
	}
	PG_RETURN_POINTER(penalty);
}

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

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

Datum
_ltree_picksplit(PG_FUNCTION_ARGS)
{
	bytea	   *entryvec = (bytea *) PG_GETARG_POINTER(0);
	GIST_SPLITVEC *v = (GIST_SPLITVEC *) PG_GETARG_POINTER(1);
	OffsetNumber k,
				j;
	ltree_gist *datum_l,
			   *datum_r;
	ABITVEC		union_l,
				union_r;
	bool		firsttime = true;
	int4		size_alpha,
				size_beta,
				sizeu,
				sizei;
	int4		size_waste,
				waste = 0.0;
	int4		size_l,
				size_r;
	int4		nbytes;
	OffsetNumber seed_1 = 0,
				seed_2 = 0;
	OffsetNumber *left,
			   *right;
	OffsetNumber maxoff;
	BITVECP		ptra,
				ptrb,
				ptrc;
	int			i;
	unsigned char valtmp;
	SPLITCOST  *costvector;
	ltree_gist *_k,
			   *_j;

	maxoff = ((VARSIZE(entryvec) - VARHDRSZ) / sizeof(GISTENTRY)) - 2;
	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))
		{
			_j = GETENTRY(entryvec, j);
			if (LTG_ISALLTRUE(_k) || LTG_ISALLTRUE(_j))
			{
				sizeu = ASIGLENBIT;
				if (LTG_ISALLTRUE(_k) && LTG_ISALLTRUE(_j))
					sizei = ASIGLENBIT;
				else
					sizei = (LTG_ISALLTRUE(_k)) ?
						sizebitvec(LTG_SIGN(_j)) : sizebitvec(LTG_SIGN(_k));
			}
			else
			{
				sizeu = sizei = 0;
				ptra = LTG_SIGN(_j);
				ptrb = LTG_SIGN(_k);
				/* critical section for bench !!! */

#define COUNT(pos) do { \
	if ( GETBITBYTE(*(char*)ptra,pos) ) { \
		sizeu++; \
		if ( GETBITBYTE(*(char*)ptrb, pos) ) \
			sizei++; \
	} else if ( GETBITBYTE(*(char*)ptrb, pos) ) \
		sizeu++; \
} while(0)

				ALOOPBYTE(
						  COUNT(0);
				COUNT(1);
				COUNT(2);
				COUNT(3);
				COUNT(4);
				COUNT(5);
				COUNT(6);
				COUNT(7);
				ptra = (BITVECP) (((char *) ptra) + 1);
				ptrb = (BITVECP) (((char *) ptrb) + 1);
				);
			}
			size_waste = sizeu - sizei;
			if (size_waste > waste || firsttime)
			{
				waste = size_waste;
				seed_1 = k;
				seed_2 = j;
				firsttime = false;
			}
		}
	}

	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 (LTG_ISALLTRUE(GETENTRY(entryvec, seed_1)))
	{
		datum_l = (ltree_gist *) palloc(LTG_HDRSIZE);
		datum_l->len = LTG_HDRSIZE;
		datum_l->flag = LTG_ALLTRUE;
		size_l = ASIGLENBIT;
	}
	else
	{
		datum_l = (ltree_gist *) palloc(LTG_HDRSIZE + ASIGLEN);
		datum_l->len = LTG_HDRSIZE + ASIGLEN;
		datum_l->flag = 0;
		memcpy((void *) LTG_SIGN(datum_l), (void *) LTG_SIGN(GETENTRY(entryvec, seed_1)), sizeof(ABITVEC));
		size_l = sizebitvec(LTG_SIGN(datum_l));
	}
	if (LTG_ISALLTRUE(GETENTRY(entryvec, seed_2)))
	{
		datum_r = (ltree_gist *) palloc(LTG_HDRSIZE);
		datum_r->len = LTG_HDRSIZE;
		datum_r->flag = LTG_ALLTRUE;
		size_r = ASIGLENBIT;
	}
	else
	{
		datum_r = (ltree_gist *) palloc(LTG_HDRSIZE + ASIGLEN);
		datum_r->len = LTG_HDRSIZE + ASIGLEN;
		datum_r->flag = 0;
		memcpy((void *) LTG_SIGN(datum_r), (void *) LTG_SIGN(GETENTRY(entryvec, seed_2)), sizeof(ABITVEC));
		size_r = sizebitvec(LTG_SIGN(datum_r));
	}

	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);
		if (LTG_ISALLTRUE(_j))
		{
			size_alpha = ASIGLENBIT - size_l;
			size_beta = ASIGLENBIT - size_r;
		}
		else
		{
			ptra = LTG_SIGN(datum_l);
			ptrb = LTG_SIGN(datum_r);
			ptrc = LTG_SIGN(_j);
			size_beta = size_alpha = 0;
			if (LTG_ISALLTRUE(datum_l))
			{
				if (!LTG_ISALLTRUE(datum_r))
				{
					ALOOPBIT(
							 if (GETBIT(ptrc, i) && !GETBIT(ptrb, i))
							 size_beta++;
					);
				}
			}
			else if (LTG_ISALLTRUE(datum_r))
			{
				if (!LTG_ISALLTRUE(datum_l))
				{
					ALOOPBIT(
							 if (GETBIT(ptrc, i) && !GETBIT(ptra, i))
							 size_alpha++;
					);
				}
			}
			else
			{
				ALOOPBIT(
						 if (GETBIT(ptrc, i) && !GETBIT(ptra, i))
						 size_alpha++;
				if (GETBIT(ptrc, i) && !GETBIT(ptrb, i))
					size_beta++;
				);
			}
		}
		costvector[j - 1].cost = abs(size_alpha - size_beta);
	}
	qsort((void *) costvector, maxoff, sizeof(SPLITCOST), comparecost);

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

		if (LTG_ISALLTRUE(datum_l) || LTG_ISALLTRUE(_j))
			size_alpha = ASIGLENBIT;
		else
		{
			ptra = LTG_SIGN(_j);
			ptrb = LTG_SIGN(datum_l);
			size_alpha = 0;
			ALOOPBYTE(
					  valtmp = union_l[i] = ptra[i] | ptrb[i];
			size_alpha += SUMBIT(valtmp);
			);
		}

		if (LTG_ISALLTRUE(datum_r) || LTG_ISALLTRUE(_j))
			size_beta = ASIGLENBIT;
		else
		{
			ptra = LTG_SIGN(_j);
			ptrb = LTG_SIGN(datum_r);
			size_beta = 0;
			ALOOPBYTE(
					  valtmp = union_r[i] = ptra[i] | ptrb[i];
			size_beta += SUMBIT(valtmp);
			);
		}

		if (size_alpha - size_l < size_beta - size_r + WISH_F(v->spl_nleft, v->spl_nright, 0.00001))
		{
			if (!LTG_ISALLTRUE(datum_l))
			{
				if (size_alpha == ASIGLENBIT)
				{
					if (size_alpha != size_l)
						MemSet((void *) LTG_SIGN(datum_l), 0xff, sizeof(ABITVEC));
				}
				else
					memcpy((void *) LTG_SIGN(datum_l), (void *) union_l, sizeof(ABITVEC));
			}
			size_l = size_alpha;
			*left++ = j;
			v->spl_nleft++;
		}
		else
		{
			if (!LTG_ISALLTRUE(datum_r))
			{
				if (size_beta == ASIGLENBIT)
				{
					if (size_beta != size_r)
						MemSet((void *) LTG_SIGN(datum_r), 0xff, sizeof(ABITVEC));
				}
				else
					memcpy((void *) LTG_SIGN(datum_r), (void *) union_r, sizeof(ABITVEC));
			}
			size_r = size_beta;
			*right++ = j;
			v->spl_nright++;
		}
	}

	*right = *left = FirstOffsetNumber;
	pfree(costvector);

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

	PG_RETURN_POINTER(v);
}

static bool
gist_te(ltree_gist * key, ltree * query)
{
	ltree_level *curq = LTREE_FIRST(query);
	BITVECP		sign = LTG_SIGN(key);
	int			qlen = query->numlevel;
	unsigned int hv;

	if (LTG_ISALLTRUE(key))
		return true;

	while (qlen > 0)
	{
		hv = ltree_crc32_sz(curq->name, curq->len);
		if (!GETBIT(sign, AHASHVAL(hv)))
			return false;
		curq = LEVEL_NEXT(curq);
		qlen--;
	}

	return true;
}

static bool
checkcondition_bit(void *checkval, ITEM * val)
{
	return (FLG_CANLOOKSIGN(val->flag)) ? GETBIT(checkval, AHASHVAL(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
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, AHASHVAL(curv->val)))
				{
					isexist = true;
					break;
				}
				curv = LVAR_NEXT(curv);
				vlen--;
			}
			if (!isexist)
				return false;
		}

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

	return true;
}

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)
                elog(ERROR, "Dimension of array != 1");

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

Datum
_ltree_consistent(PG_FUNCTION_ARGS)
{
	GISTENTRY  *entry = (GISTENTRY *) PG_GETARG_POINTER(0);
	char	   *query = (char *) DatumGetPointer(PG_DETOAST_DATUM(PG_GETARG_DATUM(1)));
	ltree_gist *key = (ltree_gist *) DatumGetPointer(entry->key);
	StrategyNumber strategy = (StrategyNumber) PG_GETARG_UINT16(2);
	bool		res = false;

#ifndef assert_enabled
#define assert_enabled 0
#endif

	switch (strategy)
	{
		case 10:
		case 11:
			res = gist_te(key, (ltree *) query);
			break;
		case 12:
		case 13:
			res = gist_qe(key, (lquery *) query);
			break;
		case 14:
		case 15:
			res = gist_qtxt(key, (ltxtquery *) query);
			break;
		case 16:
		case 17:
			res = _arrq_cons(key, (ArrayType *) query);
			break;
		default:
			elog(ERROR, "Unknown StrategyNumber: %d", strategy);
	}
	PG_RETURN_BOOL(res);
}