/* src/interfaces/ecpg/pgtypeslib/interval.c */

#include "postgres_fe.h"
#include <time.h>
#include <math.h>
#include <limits.h>

#ifdef __FAST_MATH__
#error -ffast-math is known to break this code
#endif

#include "extern.h"
#include "dt.h"
#include "pgtypes_error.h"
#include "pgtypes_interval.h"

/* copy&pasted from .../src/backend/utils/adt/datetime.c */
static int
strtoint(const char *nptr, char **endptr, int base)
{
	long		val;

	val = strtol(nptr, endptr, base);
#ifdef HAVE_LONG_INT_64
	if (val != (long) ((int32) val))
		errno = ERANGE;
#endif
	return (int) val;
}

/* copy&pasted from .../src/backend/utils/adt/datetime.c
 * and changesd struct pg_tm to struct tm
 */
static void
AdjustFractSeconds(double frac, struct /* pg_ */ tm *tm, fsec_t *fsec, int scale)
{
	int			sec;

	if (frac == 0)
		return;
	frac *= scale;
	sec = (int) frac;
	tm->tm_sec += sec;
	frac -= sec;
	*fsec += rint(frac * 1000000);
}


/* copy&pasted from .../src/backend/utils/adt/datetime.c
 * and changesd struct pg_tm to struct tm
 */
static void
AdjustFractDays(double frac, struct /* pg_ */ tm *tm, fsec_t *fsec, int scale)
{
	int			extra_days;

	if (frac == 0)
		return;
	frac *= scale;
	extra_days = (int) frac;
	tm->tm_mday += extra_days;
	frac -= extra_days;
	AdjustFractSeconds(frac, tm, fsec, SECS_PER_DAY);
}

/* copy&pasted from .../src/backend/utils/adt/datetime.c */
static int
ParseISO8601Number(char *str, char **endptr, int *ipart, double *fpart)
{
	double		val;

	if (!(isdigit((unsigned char) *str) || *str == '-' || *str == '.'))
		return DTERR_BAD_FORMAT;
	errno = 0;
	val = strtod(str, endptr);
	/* did we not see anything that looks like a double? */
	if (*endptr == str || errno != 0)
		return DTERR_BAD_FORMAT;
	/* watch out for overflow */
	if (val < INT_MIN || val > INT_MAX)
		return DTERR_FIELD_OVERFLOW;
	/* be very sure we truncate towards zero (cf dtrunc()) */
	if (val >= 0)
		*ipart = (int) floor(val);
	else
		*ipart = (int) -floor(-val);
	*fpart = val - *ipart;
	return 0;
}

/* copy&pasted from .../src/backend/utils/adt/datetime.c */
static int
ISO8601IntegerWidth(char *fieldstart)
{
	/* We might have had a leading '-' */
	if (*fieldstart == '-')
		fieldstart++;
	return strspn(fieldstart, "0123456789");
}


/* copy&pasted from .../src/backend/utils/adt/datetime.c
 * and changesd struct pg_tm to struct tm
 */
static inline void
ClearPgTm(struct /* pg_ */ tm *tm, fsec_t *fsec)
{
	tm->tm_year = 0;
	tm->tm_mon = 0;
	tm->tm_mday = 0;
	tm->tm_hour = 0;
	tm->tm_min = 0;
	tm->tm_sec = 0;
	*fsec = 0;
}

/* copy&pasted from .../src/backend/utils/adt/datetime.c
 *
 * * changesd struct pg_tm to struct tm
 *
 * * Made the function static
 */
static int
DecodeISO8601Interval(char *str,
					  int *dtype, struct /* pg_ */ tm *tm, fsec_t *fsec)
{
	bool		datepart = true;
	bool		havefield = false;

	*dtype = DTK_DELTA;
	ClearPgTm(tm, fsec);

	if (strlen(str) < 2 || str[0] != 'P')
		return DTERR_BAD_FORMAT;

	str++;
	while (*str)
	{
		char	   *fieldstart;
		int			val;
		double		fval;
		char		unit;
		int			dterr;

		if (*str == 'T')		/* T indicates the beginning of the time part */
		{
			datepart = false;
			havefield = false;
			str++;
			continue;
		}

		fieldstart = str;
		dterr = ParseISO8601Number(str, &str, &val, &fval);
		if (dterr)
			return dterr;

		/*
		 * Note: we could step off the end of the string here.  Code below
		 * *must* exit the loop if unit == '\0'.
		 */
		unit = *str++;

		if (datepart)
		{
			switch (unit)		/* before T: Y M W D */
			{
				case 'Y':
					tm->tm_year += val;
					tm->tm_mon += (fval * 12);
					break;
				case 'M':
					tm->tm_mon += val;
					AdjustFractDays(fval, tm, fsec, DAYS_PER_MONTH);
					break;
				case 'W':
					tm->tm_mday += val * 7;
					AdjustFractDays(fval, tm, fsec, 7);
					break;
				case 'D':
					tm->tm_mday += val;
					AdjustFractSeconds(fval, tm, fsec, SECS_PER_DAY);
					break;
				case 'T':		/* ISO 8601 4.4.3.3 Alternative Format / Basic */
				case '\0':
					if (ISO8601IntegerWidth(fieldstart) == 8 && !havefield)
					{
						tm->tm_year += val / 10000;
						tm->tm_mon += (val / 100) % 100;
						tm->tm_mday += val % 100;
						AdjustFractSeconds(fval, tm, fsec, SECS_PER_DAY);
						if (unit == '\0')
							return 0;
						datepart = false;
						havefield = false;
						continue;
					}
					/* Else fall through to extended alternative format */
				case '-':		/* ISO 8601 4.4.3.3 Alternative Format,
								 * Extended */
					if (havefield)
						return DTERR_BAD_FORMAT;

					tm->tm_year += val;
					tm->tm_mon += (fval * 12);
					if (unit == '\0')
						return 0;
					if (unit == 'T')
					{
						datepart = false;
						havefield = false;
						continue;
					}

					dterr = ParseISO8601Number(str, &str, &val, &fval);
					if (dterr)
						return dterr;
					tm->tm_mon += val;
					AdjustFractDays(fval, tm, fsec, DAYS_PER_MONTH);
					if (*str == '\0')
						return 0;
					if (*str == 'T')
					{
						datepart = false;
						havefield = false;
						continue;
					}
					if (*str != '-')
						return DTERR_BAD_FORMAT;
					str++;

					dterr = ParseISO8601Number(str, &str, &val, &fval);
					if (dterr)
						return dterr;
					tm->tm_mday += val;
					AdjustFractSeconds(fval, tm, fsec, SECS_PER_DAY);
					if (*str == '\0')
						return 0;
					if (*str == 'T')
					{
						datepart = false;
						havefield = false;
						continue;
					}
					return DTERR_BAD_FORMAT;
				default:
					/* not a valid date unit suffix */
					return DTERR_BAD_FORMAT;
			}
		}
		else
		{
			switch (unit)		/* after T: H M S */
			{
				case 'H':
					tm->tm_hour += val;
					AdjustFractSeconds(fval, tm, fsec, SECS_PER_HOUR);
					break;
				case 'M':
					tm->tm_min += val;
					AdjustFractSeconds(fval, tm, fsec, SECS_PER_MINUTE);
					break;
				case 'S':
					tm->tm_sec += val;
					AdjustFractSeconds(fval, tm, fsec, 1);
					break;
				case '\0':		/* ISO 8601 4.4.3.3 Alternative Format */
					if (ISO8601IntegerWidth(fieldstart) == 6 && !havefield)
					{
						tm->tm_hour += val / 10000;
						tm->tm_min += (val / 100) % 100;
						tm->tm_sec += val % 100;
						AdjustFractSeconds(fval, tm, fsec, 1);
						return 0;
					}
					/* Else fall through to extended alternative format */
				case ':':		/* ISO 8601 4.4.3.3 Alternative Format,
								 * Extended */
					if (havefield)
						return DTERR_BAD_FORMAT;

					tm->tm_hour += val;
					AdjustFractSeconds(fval, tm, fsec, SECS_PER_HOUR);
					if (unit == '\0')
						return 0;

					dterr = ParseISO8601Number(str, &str, &val, &fval);
					if (dterr)
						return dterr;
					tm->tm_min += val;
					AdjustFractSeconds(fval, tm, fsec, SECS_PER_MINUTE);
					if (*str == '\0')
						return 0;
					if (*str != ':')
						return DTERR_BAD_FORMAT;
					str++;

					dterr = ParseISO8601Number(str, &str, &val, &fval);
					if (dterr)
						return dterr;
					tm->tm_sec += val;
					AdjustFractSeconds(fval, tm, fsec, 1);
					if (*str == '\0')
						return 0;
					return DTERR_BAD_FORMAT;

				default:
					/* not a valid time unit suffix */
					return DTERR_BAD_FORMAT;
			}
		}

		havefield = true;
	}

	return 0;
}



/* copy&pasted from .../src/backend/utils/adt/datetime.c
 * with 3 exceptions
 *
 *	* changesd struct pg_tm to struct tm
 *
 *	* ECPG code called this without a 'range' parameter
 *	  removed 'int range' from the argument list and
 *	  places where DecodeTime is called; and added
 *		 int range = INTERVAL_FULL_RANGE;
 *
 *	* ECPG semes not to have a global IntervalStyle
 *	  so added
 *		int IntervalStyle = INTSTYLE_POSTGRES;
 *
 *	* Assert wasn't available so removed it.
 */
int
DecodeInterval(char **field, int *ftype, int nf,	/* int range, */
			   int *dtype, struct /* pg_ */ tm *tm, fsec_t *fsec)
{
	int			IntervalStyle = INTSTYLE_POSTGRES_VERBOSE;
	int			range = INTERVAL_FULL_RANGE;
	bool		is_before = FALSE;
	char	   *cp;
	int			fmask = 0,
				tmask,
				type;
	int			i;
	int			dterr;
	int			val;
	double		fval;

	*dtype = DTK_DELTA;
	type = IGNORE_DTF;
	ClearPgTm(tm, fsec);

	/* read through list backwards to pick up units before values */
	for (i = nf - 1; i >= 0; i--)
	{
		switch (ftype[i])
		{
			case DTK_TIME:
				dterr = DecodeTime(field[i],	/* range, */
								   &tmask, tm, fsec);
				if (dterr)
					return dterr;
				type = DTK_DAY;
				break;

			case DTK_TZ:

				/*
				 * Timezone is a token with a leading sign character and at
				 * least one digit; there could be ':', '.', '-' embedded in
				 * it as well.
				 */
				/* Assert(*field[i] == '-' || *field[i] == '+'); */

				/*
				 * Try for hh:mm or hh:mm:ss.  If not, fall through to
				 * DTK_NUMBER case, which can handle signed float numbers and
				 * signed year-month values.
				 */
				if (strchr(field[i] + 1, ':') != NULL &&
					DecodeTime(field[i] + 1,	/* INTERVAL_FULL_RANGE, */
							   &tmask, tm, fsec) == 0)
				{
					if (*field[i] == '-')
					{
						/* flip the sign on all fields */
						tm->tm_hour = -tm->tm_hour;
						tm->tm_min = -tm->tm_min;
						tm->tm_sec = -tm->tm_sec;
						*fsec = -(*fsec);
					}

					/*
					 * Set the next type to be a day, if units are not
					 * specified. This handles the case of '1 +02:03' since we
					 * are reading right to left.
					 */
					type = DTK_DAY;
					tmask = DTK_M(TZ);
					break;
				}
				/* FALL THROUGH */

			case DTK_DATE:
			case DTK_NUMBER:
				if (type == IGNORE_DTF)
				{
					/* use typmod to decide what rightmost field is */
					switch (range)
					{
						case INTERVAL_MASK(YEAR):
							type = DTK_YEAR;
							break;
						case INTERVAL_MASK(MONTH):
						case INTERVAL_MASK(YEAR) | INTERVAL_MASK(MONTH):
							type = DTK_MONTH;
							break;
						case INTERVAL_MASK(DAY):
							type = DTK_DAY;
							break;
						case INTERVAL_MASK(HOUR):
						case INTERVAL_MASK(DAY) | INTERVAL_MASK(HOUR):
						case INTERVAL_MASK(DAY) | INTERVAL_MASK(HOUR) | INTERVAL_MASK(MINUTE):
						case INTERVAL_MASK(DAY) | INTERVAL_MASK(HOUR) | INTERVAL_MASK(MINUTE) | INTERVAL_MASK(SECOND):
							type = DTK_HOUR;
							break;
						case INTERVAL_MASK(MINUTE):
						case INTERVAL_MASK(HOUR) | INTERVAL_MASK(MINUTE):
							type = DTK_MINUTE;
							break;
						case INTERVAL_MASK(SECOND):
						case INTERVAL_MASK(HOUR) | INTERVAL_MASK(MINUTE) | INTERVAL_MASK(SECOND):
						case INTERVAL_MASK(MINUTE) | INTERVAL_MASK(SECOND):
							type = DTK_SECOND;
							break;
						default:
							type = DTK_SECOND;
							break;
					}
				}

				errno = 0;
				val = strtoint(field[i], &cp, 10);
				if (errno == ERANGE)
					return DTERR_FIELD_OVERFLOW;

				if (*cp == '-')
				{
					/* SQL "years-months" syntax */
					int			val2;

					val2 = strtoint(cp + 1, &cp, 10);
					if (errno == ERANGE || val2 < 0 || val2 >= MONTHS_PER_YEAR)
						return DTERR_FIELD_OVERFLOW;
					if (*cp != '\0')
						return DTERR_BAD_FORMAT;
					type = DTK_MONTH;
					if (*field[i] == '-')
						val2 = -val2;
					val = val * MONTHS_PER_YEAR + val2;
					fval = 0;
				}
				else if (*cp == '.')
				{
					errno = 0;
					fval = strtod(cp, &cp);
					if (*cp != '\0' || errno != 0)
						return DTERR_BAD_FORMAT;

					if (*field[i] == '-')
						fval = -fval;
				}
				else if (*cp == '\0')
					fval = 0;
				else
					return DTERR_BAD_FORMAT;

				tmask = 0;		/* DTK_M(type); */

				switch (type)
				{
					case DTK_MICROSEC:
						*fsec += rint(val + fval);
						tmask = DTK_M(MICROSECOND);
						break;

					case DTK_MILLISEC:
						*fsec += rint((val + fval) * 1000);
						tmask = DTK_M(MILLISECOND);
						break;

					case DTK_SECOND:
						tm->tm_sec += val;
						*fsec += rint(fval * 1000000);

						/*
						 * If any subseconds were specified, consider this
						 * microsecond and millisecond input as well.
						 */
						if (fval == 0)
							tmask = DTK_M(SECOND);
						else
							tmask = DTK_ALL_SECS_M;
						break;

					case DTK_MINUTE:
						tm->tm_min += val;
						AdjustFractSeconds(fval, tm, fsec, SECS_PER_MINUTE);
						tmask = DTK_M(MINUTE);
						break;

					case DTK_HOUR:
						tm->tm_hour += val;
						AdjustFractSeconds(fval, tm, fsec, SECS_PER_HOUR);
						tmask = DTK_M(HOUR);
						type = DTK_DAY;
						break;

					case DTK_DAY:
						tm->tm_mday += val;
						AdjustFractSeconds(fval, tm, fsec, SECS_PER_DAY);
						tmask = (fmask & DTK_M(DAY)) ? 0 : DTK_M(DAY);
						break;

					case DTK_WEEK:
						tm->tm_mday += val * 7;
						AdjustFractDays(fval, tm, fsec, 7);
						tmask = (fmask & DTK_M(DAY)) ? 0 : DTK_M(DAY);
						break;

					case DTK_MONTH:
						tm->tm_mon += val;
						AdjustFractDays(fval, tm, fsec, DAYS_PER_MONTH);
						tmask = DTK_M(MONTH);
						break;

					case DTK_YEAR:
						tm->tm_year += val;
						if (fval != 0)
							tm->tm_mon += fval * MONTHS_PER_YEAR;
						tmask = (fmask & DTK_M(YEAR)) ? 0 : DTK_M(YEAR);
						break;

					case DTK_DECADE:
						tm->tm_year += val * 10;
						if (fval != 0)
							tm->tm_mon += fval * MONTHS_PER_YEAR * 10;
						tmask = (fmask & DTK_M(YEAR)) ? 0 : DTK_M(YEAR);
						break;

					case DTK_CENTURY:
						tm->tm_year += val * 100;
						if (fval != 0)
							tm->tm_mon += fval * MONTHS_PER_YEAR * 100;
						tmask = (fmask & DTK_M(YEAR)) ? 0 : DTK_M(YEAR);
						break;

					case DTK_MILLENNIUM:
						tm->tm_year += val * 1000;
						if (fval != 0)
							tm->tm_mon += fval * MONTHS_PER_YEAR * 1000;
						tmask = (fmask & DTK_M(YEAR)) ? 0 : DTK_M(YEAR);
						break;

					default:
						return DTERR_BAD_FORMAT;
				}
				break;

			case DTK_STRING:
			case DTK_SPECIAL:
				type = DecodeUnits(i, field[i], &val);
				if (type == IGNORE_DTF)
					continue;

				tmask = 0;		/* DTK_M(type); */
				switch (type)
				{
					case UNITS:
						type = val;
						break;

					case AGO:
						is_before = TRUE;
						type = val;
						break;

					case RESERV:
						tmask = (DTK_DATE_M | DTK_TIME_M);
						*dtype = val;
						break;

					default:
						return DTERR_BAD_FORMAT;
				}
				break;

			default:
				return DTERR_BAD_FORMAT;
		}

		if (tmask & fmask)
			return DTERR_BAD_FORMAT;
		fmask |= tmask;
	}

	/* ensure that at least one time field has been found */
	if (fmask == 0)
		return DTERR_BAD_FORMAT;

	/* ensure fractional seconds are fractional */
	if (*fsec != 0)
	{
		int			sec;

		sec = *fsec / USECS_PER_SEC;
		*fsec -= sec * USECS_PER_SEC;
		tm->tm_sec += sec;
	}

	/*----------
	 * The SQL standard defines the interval literal
	 *	 '-1 1:00:00'
	 * to mean "negative 1 days and negative 1 hours", while Postgres
	 * traditionally treats this as meaning "negative 1 days and positive
	 * 1 hours".  In SQL_STANDARD intervalstyle, we apply the leading sign
	 * to all fields if there are no other explicit signs.
	 *
	 * We leave the signs alone if there are additional explicit signs.
	 * This protects us against misinterpreting postgres-style dump output,
	 * since the postgres-style output code has always put an explicit sign on
	 * all fields following a negative field.  But note that SQL-spec output
	 * is ambiguous and can be misinterpreted on load!	(So it's best practice
	 * to dump in postgres style, not SQL style.)
	 *----------
	 */
	if (IntervalStyle == INTSTYLE_SQL_STANDARD && *field[0] == '-')
	{
		/* Check for additional explicit signs */
		bool		more_signs = false;

		for (i = 1; i < nf; i++)
		{
			if (*field[i] == '-' || *field[i] == '+')
			{
				more_signs = true;
				break;
			}
		}

		if (!more_signs)
		{
			/*
			 * Rather than re-determining which field was field[0], just force
			 * 'em all negative.
			 */
			if (*fsec > 0)
				*fsec = -(*fsec);
			if (tm->tm_sec > 0)
				tm->tm_sec = -tm->tm_sec;
			if (tm->tm_min > 0)
				tm->tm_min = -tm->tm_min;
			if (tm->tm_hour > 0)
				tm->tm_hour = -tm->tm_hour;
			if (tm->tm_mday > 0)
				tm->tm_mday = -tm->tm_mday;
			if (tm->tm_mon > 0)
				tm->tm_mon = -tm->tm_mon;
			if (tm->tm_year > 0)
				tm->tm_year = -tm->tm_year;
		}
	}

	/* finally, AGO negates everything */
	if (is_before)
	{
		*fsec = -(*fsec);
		tm->tm_sec = -tm->tm_sec;
		tm->tm_min = -tm->tm_min;
		tm->tm_hour = -tm->tm_hour;
		tm->tm_mday = -tm->tm_mday;
		tm->tm_mon = -tm->tm_mon;
		tm->tm_year = -tm->tm_year;
	}

	return 0;
}


/* copy&pasted from .../src/backend/utils/adt/datetime.c */
static char *
AddVerboseIntPart(char *cp, int value, const char *units,
				  bool *is_zero, bool *is_before)
{
	if (value == 0)
		return cp;
	/* first nonzero value sets is_before */
	if (*is_zero)
	{
		*is_before = (value < 0);
		value = abs(value);
	}
	else if (*is_before)
		value = -value;
	sprintf(cp, " %d %s%s", value, units, (value == 1) ? "" : "s");
	*is_zero = FALSE;
	return cp + strlen(cp);
}

/* copy&pasted from .../src/backend/utils/adt/datetime.c */
static char *
AddPostgresIntPart(char *cp, int value, const char *units,
				   bool *is_zero, bool *is_before)
{
	if (value == 0)
		return cp;
	sprintf(cp, "%s%s%d %s%s",
			(!*is_zero) ? " " : "",
			(*is_before && value > 0) ? "+" : "",
			value,
			units,
			(value != 1) ? "s" : "");

	/*
	 * Each nonzero field sets is_before for (only) the next one.  This is a
	 * tad bizarre but it's how it worked before...
	 */
	*is_before = (value < 0);
	*is_zero = FALSE;
	return cp + strlen(cp);
}

/* copy&pasted from .../src/backend/utils/adt/datetime.c */
static char *
AddISO8601IntPart(char *cp, int value, char units)
{
	if (value == 0)
		return cp;
	sprintf(cp, "%d%c", value, units);
	return cp + strlen(cp);
}

/* copy&pasted from .../src/backend/utils/adt/datetime.c */
static void
AppendSeconds(char *cp, int sec, fsec_t fsec, int precision, bool fillzeros)
{
	if (fsec == 0)
	{
		if (fillzeros)
			sprintf(cp, "%02d", abs(sec));
		else
			sprintf(cp, "%d", abs(sec));
	}
	else
	{
		if (fillzeros)
			sprintf(cp, "%02d.%0*d", abs(sec), precision, (int) Abs(fsec));
		else
			sprintf(cp, "%d.%0*d", abs(sec), precision, (int) Abs(fsec));
		TrimTrailingZeros(cp);
	}
}


/* copy&pasted from .../src/backend/utils/adt/datetime.c
 *
 * Change pg_tm to tm
 */

int
EncodeInterval(struct /* pg_ */ tm *tm, fsec_t fsec, int style, char *str)
{
	char	   *cp = str;
	int			year = tm->tm_year;
	int			mon = tm->tm_mon;
	int			mday = tm->tm_mday;
	int			hour = tm->tm_hour;
	int			min = tm->tm_min;
	int			sec = tm->tm_sec;
	bool		is_before = FALSE;
	bool		is_zero = TRUE;

	/*
	 * The sign of year and month are guaranteed to match, since they are
	 * stored internally as "month". But we'll need to check for is_before and
	 * is_zero when determining the signs of day and hour/minute/seconds
	 * fields.
	 */
	switch (style)
	{
			/* SQL Standard interval format */
		case INTSTYLE_SQL_STANDARD:
			{
				bool		has_negative = year < 0 || mon < 0 ||
				mday < 0 || hour < 0 ||
				min < 0 || sec < 0 || fsec < 0;
				bool		has_positive = year > 0 || mon > 0 ||
				mday > 0 || hour > 0 ||
				min > 0 || sec > 0 || fsec > 0;
				bool		has_year_month = year != 0 || mon != 0;
				bool		has_day_time = mday != 0 || hour != 0 ||
				min != 0 || sec != 0 || fsec != 0;
				bool		has_day = mday != 0;
				bool		sql_standard_value = !(has_negative && has_positive) &&
				!(has_year_month && has_day_time);

				/*
				 * SQL Standard wants only 1 "<sign>" preceding the whole
				 * interval ... but can't do that if mixed signs.
				 */
				if (has_negative && sql_standard_value)
				{
					*cp++ = '-';
					year = -year;
					mon = -mon;
					mday = -mday;
					hour = -hour;
					min = -min;
					sec = -sec;
					fsec = -fsec;
				}

				if (!has_negative && !has_positive)
				{
					sprintf(cp, "0");
				}
				else if (!sql_standard_value)
				{
					/*
					 * For non sql-standard interval values, force outputting
					 * the signs to avoid ambiguities with intervals with
					 * mixed sign components.
					 */
					char		year_sign = (year < 0 || mon < 0) ? '-' : '+';
					char		day_sign = (mday < 0) ? '-' : '+';
					char		sec_sign = (hour < 0 || min < 0 ||
											sec < 0 || fsec < 0) ? '-' : '+';

					sprintf(cp, "%c%d-%d %c%d %c%d:%02d:",
							year_sign, abs(year), abs(mon),
							day_sign, abs(mday),
							sec_sign, abs(hour), abs(min));
					cp += strlen(cp);
					AppendSeconds(cp, sec, fsec, MAX_INTERVAL_PRECISION, true);
				}
				else if (has_year_month)
				{
					sprintf(cp, "%d-%d", year, mon);
				}
				else if (has_day)
				{
					sprintf(cp, "%d %d:%02d:", mday, hour, min);
					cp += strlen(cp);
					AppendSeconds(cp, sec, fsec, MAX_INTERVAL_PRECISION, true);
				}
				else
				{
					sprintf(cp, "%d:%02d:", hour, min);
					cp += strlen(cp);
					AppendSeconds(cp, sec, fsec, MAX_INTERVAL_PRECISION, true);
				}
			}
			break;

			/* ISO 8601 "time-intervals by duration only" */
		case INTSTYLE_ISO_8601:
			/* special-case zero to avoid printing nothing */
			if (year == 0 && mon == 0 && mday == 0 &&
				hour == 0 && min == 0 && sec == 0 && fsec == 0)
			{
				sprintf(cp, "PT0S");
				break;
			}
			*cp++ = 'P';
			cp = AddISO8601IntPart(cp, year, 'Y');
			cp = AddISO8601IntPart(cp, mon, 'M');
			cp = AddISO8601IntPart(cp, mday, 'D');
			if (hour != 0 || min != 0 || sec != 0 || fsec != 0)
				*cp++ = 'T';
			cp = AddISO8601IntPart(cp, hour, 'H');
			cp = AddISO8601IntPart(cp, min, 'M');
			if (sec != 0 || fsec != 0)
			{
				if (sec < 0 || fsec < 0)
					*cp++ = '-';
				AppendSeconds(cp, sec, fsec, MAX_INTERVAL_PRECISION, false);
				cp += strlen(cp);
				*cp++ = 'S';
				*cp = '\0';
			}
			break;

			/* Compatible with postgresql < 8.4 when DateStyle = 'iso' */
		case INTSTYLE_POSTGRES:
			cp = AddPostgresIntPart(cp, year, "year", &is_zero, &is_before);
			cp = AddPostgresIntPart(cp, mon, "mon", &is_zero, &is_before);
			cp = AddPostgresIntPart(cp, mday, "day", &is_zero, &is_before);
			if (is_zero || hour != 0 || min != 0 || sec != 0 || fsec != 0)
			{
				bool		minus = (hour < 0 || min < 0 || sec < 0 || fsec < 0);

				sprintf(cp, "%s%s%02d:%02d:",
						is_zero ? "" : " ",
						(minus ? "-" : (is_before ? "+" : "")),
						abs(hour), abs(min));
				cp += strlen(cp);
				AppendSeconds(cp, sec, fsec, MAX_INTERVAL_PRECISION, true);
			}
			break;

			/* Compatible with postgresql < 8.4 when DateStyle != 'iso' */
		case INTSTYLE_POSTGRES_VERBOSE:
		default:
			strcpy(cp, "@");
			cp++;
			cp = AddVerboseIntPart(cp, year, "year", &is_zero, &is_before);
			cp = AddVerboseIntPart(cp, mon, "mon", &is_zero, &is_before);
			cp = AddVerboseIntPart(cp, mday, "day", &is_zero, &is_before);
			cp = AddVerboseIntPart(cp, hour, "hour", &is_zero, &is_before);
			cp = AddVerboseIntPart(cp, min, "min", &is_zero, &is_before);
			if (sec != 0 || fsec != 0)
			{
				*cp++ = ' ';
				if (sec < 0 || (sec == 0 && fsec < 0))
				{
					if (is_zero)
						is_before = TRUE;
					else if (!is_before)
						*cp++ = '-';
				}
				else if (is_before)
					*cp++ = '-';
				AppendSeconds(cp, sec, fsec, MAX_INTERVAL_PRECISION, false);
				cp += strlen(cp);
				sprintf(cp, " sec%s",
						(abs(sec) != 1 || fsec != 0) ? "s" : "");
				is_zero = FALSE;
			}
			/* identically zero? then put in a unitless zero... */
			if (is_zero)
				strcat(cp, " 0");
			if (is_before)
				strcat(cp, " ago");
			break;
	}

	return 0;
}								/* EncodeInterval() */


/* interval2tm()
 * Convert an interval data type to a tm structure.
 */
static int
interval2tm(interval span, struct tm *tm, fsec_t *fsec)
{
	int64		time;

	if (span.month != 0)
	{
		tm->tm_year = span.month / MONTHS_PER_YEAR;
		tm->tm_mon = span.month % MONTHS_PER_YEAR;

	}
	else
	{
		tm->tm_year = 0;
		tm->tm_mon = 0;
	}

	time = span.time;

	tm->tm_mday = time / USECS_PER_DAY;
	time -= tm->tm_mday * USECS_PER_DAY;
	tm->tm_hour = time / USECS_PER_HOUR;
	time -= tm->tm_hour * USECS_PER_HOUR;
	tm->tm_min = time / USECS_PER_MINUTE;
	time -= tm->tm_min * USECS_PER_MINUTE;
	tm->tm_sec = time / USECS_PER_SEC;
	*fsec = time - (tm->tm_sec * USECS_PER_SEC);

	return 0;
}								/* interval2tm() */

static int
tm2interval(struct tm *tm, fsec_t fsec, interval * span)
{
	if ((double) tm->tm_year * MONTHS_PER_YEAR + tm->tm_mon > INT_MAX ||
		(double) tm->tm_year * MONTHS_PER_YEAR + tm->tm_mon < INT_MIN)
		return -1;
	span->month = tm->tm_year * MONTHS_PER_YEAR + tm->tm_mon;
	span->time = (((((((tm->tm_mday * INT64CONST(24)) +
					   tm->tm_hour) * INT64CONST(60)) +
					 tm->tm_min) * INT64CONST(60)) +
				   tm->tm_sec) * USECS_PER_SEC) + fsec;

	return 0;
}								/* tm2interval() */

interval *
PGTYPESinterval_new(void)
{
	interval   *result;

	result = (interval *) pgtypes_alloc(sizeof(interval));
	/* result can be NULL if we run out of memory */
	return result;
}

void
PGTYPESinterval_free(interval * intvl)
{
	free(intvl);
}

interval *
PGTYPESinterval_from_asc(char *str, char **endptr)
{
	interval   *result = NULL;
	fsec_t		fsec;
	struct tm	tt,
			   *tm = &tt;
	int			dtype;
	int			nf;
	char	   *field[MAXDATEFIELDS];
	int			ftype[MAXDATEFIELDS];
	char		lowstr[MAXDATELEN + MAXDATEFIELDS];
	char	   *realptr;
	char	  **ptr = (endptr != NULL) ? endptr : &realptr;

	tm->tm_year = 0;
	tm->tm_mon = 0;
	tm->tm_mday = 0;
	tm->tm_hour = 0;
	tm->tm_min = 0;
	tm->tm_sec = 0;
	fsec = 0;

	if (strlen(str) > MAXDATELEN)
	{
		errno = PGTYPES_INTVL_BAD_INTERVAL;
		return NULL;
	}

	if (ParseDateTime(str, lowstr, field, ftype, &nf, ptr) != 0 ||
		(DecodeInterval(field, ftype, nf, &dtype, tm, &fsec) != 0 &&
		 DecodeISO8601Interval(str, &dtype, tm, &fsec) != 0))
	{
		errno = PGTYPES_INTVL_BAD_INTERVAL;
		return NULL;
	}

	result = (interval *) pgtypes_alloc(sizeof(interval));
	if (!result)
		return NULL;

	if (dtype != DTK_DELTA)
	{
		errno = PGTYPES_INTVL_BAD_INTERVAL;
		free(result);
		return NULL;
	}

	if (tm2interval(tm, fsec, result) != 0)
	{
		errno = PGTYPES_INTVL_BAD_INTERVAL;
		free(result);
		return NULL;
	}

	errno = 0;
	return result;
}

char *
PGTYPESinterval_to_asc(interval * span)
{
	struct tm	tt,
			   *tm = &tt;
	fsec_t		fsec;
	char		buf[MAXDATELEN + 1];
	int			IntervalStyle = INTSTYLE_POSTGRES_VERBOSE;

	if (interval2tm(*span, tm, &fsec) != 0)
	{
		errno = PGTYPES_INTVL_BAD_INTERVAL;
		return NULL;
	}

	if (EncodeInterval(tm, fsec, IntervalStyle, buf) != 0)
	{
		errno = PGTYPES_INTVL_BAD_INTERVAL;
		return NULL;
	}

	return pgtypes_strdup(buf);
}

int
PGTYPESinterval_copy(interval * intvlsrc, interval * intvldest)
{
	intvldest->time = intvlsrc->time;
	intvldest->month = intvlsrc->month;

	return 0;
}
