/*
 * stolen from 
 * contrib/hstore/hstore_io.c
 */
#include "postgres.h"

#include "catalog/pg_type.h"
#include "funcapi.h"
#include "lib/stringinfo.h"
#include "utils/json.h"
#include "utils/builtins.h"

#include "json_extra.h"
#include "hstore.h"

/*
 * hstore_to_json_loose
 *
 * This is a heuristic conversion to json which treats
 * 't' and 'f' as booleans and strings that look like numbers as numbers,
 * as long as they don't start with a leading zero followed by another digit
 * (think zip codes or phone numbers starting with 0).
 */
PG_FUNCTION_INFO_V1(hstore_to_json_loose);

Datum
hstore_to_json_loose(PG_FUNCTION_ARGS)
{
	HStore	   *in = PG_GETARG_HS(0);
	int			buflen,
				i;
	int			count = HS_COUNT(in);
	char	   *out,
			   *ptr;
	char	   *base = STRPTR(in);
	HEntry	   *entries = ARRPTR(in);
	bool        is_number;
	StringInfo  src, dst;

	if (count == 0)
	{
		out = palloc(1);
		*out = '\0';
		PG_RETURN_TEXT_P(cstring_to_text(out));
	}

	buflen = 3;

	/*
	 * Formula adjusted slightly from the logic in hstore_out.
	 * We have to take account of out treatment of booleans
	 * to be a bit more pessimistic about the length of values.
	 */

	for (i = 0; i < count; i++)
	{
		/* include "" and colon-space and comma-space */
		buflen += 6 + 2 * HS_KEYLEN(entries, i);
		/* include "" only if nonnull */
		buflen += 3 + (HS_VALISNULL(entries, i)
					   ? 1
					   :  2 * HS_VALLEN(entries, i));
	}

	out = ptr = palloc(buflen);

	src = makeStringInfo();
	dst = makeStringInfo();

	*ptr++ = '{';

	for (i = 0; i < count; i++)
	{
	    resetStringInfo(src);
		resetStringInfo(dst);
		appendBinaryStringInfo(src, HS_KEY(entries, base, i), HS_KEYLEN(entries, i));
		escape_json(dst, src->data);	
		strncpy(ptr, dst->data, dst->len);
		ptr += dst->len;
		*ptr++ = ':';
		*ptr++ = ' ';
		resetStringInfo(dst);
		if (HS_VALISNULL(entries, i))
			appendStringInfoString(dst,"null");
		/* guess that values of 't' or 'f' are booleans */
		else if (HS_VALLEN(entries, i) == 1 && *(HS_VAL(entries, base, i)) == 't')
			appendStringInfoString(dst,"true");
		else if (HS_VALLEN(entries, i) == 1 && *(HS_VAL(entries, base, i)) == 'f')
			appendStringInfoString(dst,"false");
		else
		{
			is_number = false;
			resetStringInfo(src);
			appendBinaryStringInfo(src, HS_VAL(entries, base, i), HS_VALLEN(entries, i));
			/* 
			 * don't treat something with a leading zero followed by another digit as numeric - 
			 * could be a zip code or similar 
			 */
			if (src->len > 0 && (src->data[0] != '0' || !isdigit(src->data[1])) &&
				strspn(src->data,"+-0123456789Ee.") == src->len)
			{
				/* might be a number. See if we can input it as a numeric value*/
				char * endptr;
				long longres = strtol(src->data,&endptr,10);
				if (*endptr == '\0')
				{
					/* strol man page says this means the whole string is valid */
					is_number = true;
				}
				else
				{
					/* not an int - try a double */
					double doubleres = strtod(src->data,&endptr);
					if (*endptr == '\0')
						is_number = true;
					else if (false)
					{
						/* shut the compiler up about unused variables */
						longres = (long) doubleres;
						longres = longres / 2;
					}
				}
			}
			if (is_number)
				appendBinaryStringInfo(dst,src->data, src->len);
			else
				escape_json(dst, src->data);
		}
		strncpy(ptr, dst->data, dst->len);
		ptr += dst->len;
		
		if (i + 1 != count)
		{
			*ptr++ = ',';
			*ptr++ = ' ';
		}
	}
	*ptr++ = '}';
	*ptr = '\0';

	PG_RETURN_TEXT_P(cstring_to_text(out));
}

PG_FUNCTION_INFO_V1(hstore_to_json);
Datum
hstore_to_json(PG_FUNCTION_ARGS)
{
	HStore	   *in = PG_GETARG_HS(0);
	int			buflen,
				i;
	int			count = HS_COUNT(in);
	char	   *out,
			   *ptr;
	char	   *base = STRPTR(in);
	HEntry	   *entries = ARRPTR(in);
	StringInfo  src, dst;

	if (count == 0)
	{
		out = palloc(1);
		*out = '\0';
		PG_RETURN_TEXT_P(cstring_to_text(out));
	}

	buflen = 3;

	/*
	 * Formula adjusted slightly from the logic in hstore_out.
	 * We have to take account of out treatment of booleans
	 * to be a bit more pessimistic about the length of values.
	 */

	for (i = 0; i < count; i++)
	{
		/* include "" and colon-space and comma-space */
		buflen += 6 + 2 * HS_KEYLEN(entries, i);
		/* include "" only if nonnull */
		buflen += 3 + (HS_VALISNULL(entries, i)
					   ? 1
					   :  2 * HS_VALLEN(entries, i));
	}

	out = ptr = palloc(buflen);

	src = makeStringInfo();
	dst = makeStringInfo();

	*ptr++ = '{';

	for (i = 0; i < count; i++)
	{
	    resetStringInfo(src);
		resetStringInfo(dst);
		appendBinaryStringInfo(src, HS_KEY(entries, base, i), HS_KEYLEN(entries, i));
		escape_json(dst, src->data);	
		strncpy(ptr, dst->data, dst->len);
		ptr += dst->len;
		*ptr++ = ':';
		*ptr++ = ' ';
		resetStringInfo(dst);
		if (HS_VALISNULL(entries, i))
			appendStringInfoString(dst,"null");
		else
		{
			resetStringInfo(src);
			appendBinaryStringInfo(src, HS_VAL(entries, base, i), HS_VALLEN(entries, i));
			escape_json(dst, src->data);
		}
		strncpy(ptr, dst->data, dst->len);
		ptr += dst->len;
		
		if (i + 1 != count)
		{
			*ptr++ = ',';
			*ptr++ = ' ';
		}
	}
	*ptr++ = '}';
	*ptr = '\0';

	PG_RETURN_TEXT_P(cstring_to_text(out));
}