#include "hstore.h"

#include "access/gin.h"   

#define	KEYFLAG		'K'
#define	VALFLAG		'V'
#define	NULLFLAG	'N'

PG_FUNCTION_INFO_V1(gin_extract_hstore);
Datum       gin_extract_hstore(PG_FUNCTION_ARGS);

static text*
makeitem( char *str, int len )
{
	text	*item;

	item = (text*)palloc( VARHDRSZ + len + 1 );
	SET_VARSIZE(item, VARHDRSZ + len + 1);

	if ( str && len > 0 )
		memcpy( VARDATA(item)+1, str, len );

	return item;
}

Datum
gin_extract_hstore(PG_FUNCTION_ARGS)
{
	HStore	*hs = PG_GETARG_HS(0);
	int32	*nentries = (int32 *) PG_GETARG_POINTER(1);
	Datum	*entries = NULL;

	*nentries = 2*hs->size;

	if ( hs->size > 0 )
	{
		HEntry	*ptr = ARRPTR(hs);
		char    *words = STRPTR(hs);
		int		i=0;

		entries = (Datum*)palloc( sizeof(Datum) * 2 * hs->size );

		while (ptr - ARRPTR(hs) < hs->size)
		{
			text	*item;

			item = makeitem( words + ptr->pos, ptr->keylen ); 
			*VARDATA(item) = KEYFLAG;
			entries[i++] = PointerGetDatum(item);

			if ( ptr->valisnull )
			{
				item = makeitem( NULL, 0 ); 
				*VARDATA(item) = NULLFLAG;

			}
			else
			{
				item = makeitem( words + ptr->pos + ptr->keylen, ptr->vallen ); 
				*VARDATA(item) = VALFLAG;
			}
			entries[i++] = PointerGetDatum(item);

			ptr++;
		}
	}

	PG_FREE_IF_COPY(hs,0);
	PG_RETURN_POINTER(entries);
}

PG_FUNCTION_INFO_V1(gin_extract_hstore_query);
Datum       gin_extract_hstore_query(PG_FUNCTION_ARGS);

Datum
gin_extract_hstore_query(PG_FUNCTION_ARGS)
{
	StrategyNumber strategy = PG_GETARG_UINT16(2);

	if ( strategy == HStoreContainsStrategyNumber )
	{
		PG_RETURN_DATUM( DirectFunctionCall2(
				gin_extract_hstore,
				PG_GETARG_DATUM(0),
				PG_GETARG_DATUM(1)
		));
	}
	else if ( strategy == HStoreExistsStrategyNumber )
	{
		text *item, *q = PG_GETARG_TEXT_P(0);
		int32	*nentries = (int32 *) PG_GETARG_POINTER(1);
		Datum	*entries = NULL;

		*nentries = 1;
		entries = (Datum*)palloc( sizeof(Datum) );

		item = makeitem( VARDATA(q), VARSIZE(q)-VARHDRSZ );
		*VARDATA(item) = KEYFLAG;
		entries[0] = PointerGetDatum(item);

		PG_RETURN_POINTER(entries);
	}
	else
		elog(ERROR, "Unsupported strategy number: %d", strategy);

	PG_RETURN_POINTER(NULL);
}

PG_FUNCTION_INFO_V1(gin_consistent_hstore);
Datum       gin_consistent_hstore(PG_FUNCTION_ARGS);

Datum
gin_consistent_hstore(PG_FUNCTION_ARGS)
{
	StrategyNumber strategy = PG_GETARG_UINT16(1);
	bool	res = true;

	if ( strategy == HStoreContainsStrategyNumber )
	{
		bool    *check = (bool *) PG_GETARG_POINTER(0);
		HStore	*query = PG_GETARG_HS(2);
		int 	i;

		for(i=0;res && i<2*query->size;i++)
			if ( check[i] == false )
				res = false;
	}
	else if ( strategy == HStoreExistsStrategyNumber )
		res = true;
	else
		elog(ERROR, "Unsupported strategy number: %d", strategy);

	PG_RETURN_BOOL(res);
}