Move all time_bucket funtions to same source file

This change moves all time_bucket-related functions to the same source
file (time_bucket.c) for consistency. There are no changes to code
logic.

src/time_bucket.c

@@ -1,8 +1,15 @@
 #include <postgres.h>
+#include <utils/timestamp.h>
+#include <utils/datetime.h>
+#include <utils/date.h>
 #include <fmgr.h>
 
 #include "compat.h"
 
+#if PG10
+#include <utils/fmgrprotos.h>
+#endif
+
 #define TIME_BUCKET(period, timestamp, min, result)			\
 	do															\
 	{															\
@@ -56,3 +63,182 @@ ts_int64_bucket(PG_FUNCTION_ARGS)
 
 	PG_RETURN_INT64(result);
 }
+
+#ifdef HAVE_INT64_TIMESTAMP
+#define JAN_3_2000 (2 * USECS_PER_DAY)
+#else
+#define JAN_3_2000 (2 * SECS_PER_DAY)
+#endif
+
+/*
+* The default origin is Monday 2000-01-03. We don't use PG epoch since it starts on a saturday.
+* This makes time-buckets by a week more intuitive and aligns it with
+* date_trunc.
+*/
+#define DEFAULT_ORIGIN (JAN_3_2000)
+#define TIME_BUCKET_TS(period, timestamp, result, shift)			\
+	do															\
+	{															\
+		if (period <= 0) \
+			ereport(ERROR, \
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE), \
+				 errmsg("period must be greater then 0"))); \
+		/* shift = shift % period, but use TMODULO */		\
+		TMODULO(shift, result, period);						\
+																		\
+		if ((shift > 0 && timestamp < DT_NOBEGIN + shift)           \
+			|| (shift < 0 && timestamp > DT_NOEND + shift))               \
+			ereport(ERROR,                                          \
+					(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),   \
+					 errmsg("timestamp out of range")));            \
+		timestamp -= shift;											\
+																	\
+		/* result = (timestamp / period) * period */					\
+		TMODULO(timestamp, result, period);								\
+		if (timestamp < 0)												\
+		{																\
+		/*																\
+		 * need to subtract another period if remainder < 0 this only happens \
+		 * if timestamp is negative to begin with and there is a remainder \
+		 * after division. Need to subtract another period since division \
+		 * truncates toward 0 in C99. \
+		 */																\
+		result = (result * period) - period;							\
+		}																	\
+		else																\
+			result *= period;												\
+																			\
+		result += shift; \
+	} while (0)
+
+/* Returns the period in the same representation as Postgres Timestamps.
+ * (i.e. in microseconds if  HAVE_INT64_TIMESTAMP, seconds otherwise).
+ * Note that this is not our internal representation (microseconds).
+ * Always returns an exact value.*/
+static inline int64
+get_interval_period_timestamp_units(Interval *interval)
+{
+	if (interval->month != 0)
+	{
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("interval defined in terms of month, year, century etc. not supported")
+				 ));
+	}
+#ifdef HAVE_INT64_TIMESTAMP
+	return interval->time + (interval->day * USECS_PER_DAY);
+#else
+	if (interval->time != trunc(interval->time))
+	{
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("interval must not have sub-second precision")
+				 ));
+	}
+	return interval->time + (interval->day * SECS_PER_DAY);
+#endif
+}
+
+TS_FUNCTION_INFO_V1(ts_timestamp_bucket);
+
+Datum
+ts_timestamp_bucket(PG_FUNCTION_ARGS)
+{
+	Interval   *interval = PG_GETARG_INTERVAL_P(0);
+	Timestamp	timestamp = PG_GETARG_TIMESTAMP(1);
+
+	/*
+	 * USE NARGS and not IS_NULL to differentiate a NULL argument from a call
+	 * with 2 parameters
+	 */
+	Timestamp	origin = (PG_NARGS() > 2 ? PG_GETARG_TIMESTAMP(2) : DEFAULT_ORIGIN);
+	Timestamp	result;
+	int64		period = get_interval_period_timestamp_units(interval);
+
+	if (TIMESTAMP_NOT_FINITE(timestamp))
+		PG_RETURN_TIMESTAMP(timestamp);
+
+	TIME_BUCKET_TS(period, timestamp, result, origin);
+
+	PG_RETURN_TIMESTAMP(result);
+}
+
+TS_FUNCTION_INFO_V1(ts_timestamptz_bucket);
+
+Datum
+ts_timestamptz_bucket(PG_FUNCTION_ARGS)
+{
+	Interval   *interval = PG_GETARG_INTERVAL_P(0);
+	TimestampTz timestamp = PG_GETARG_TIMESTAMPTZ(1);
+
+	/*
+	 * USE NARGS and not IS_NULL to differentiate a NULL argument from a call
+	 * with 2 parameters
+	 */
+	TimestampTz origin = (PG_NARGS() > 2 ? PG_GETARG_TIMESTAMPTZ(2) : DEFAULT_ORIGIN);
+	TimestampTz result;
+	int64		period = get_interval_period_timestamp_units(interval);
+
+	if (TIMESTAMP_NOT_FINITE(timestamp))
+		PG_RETURN_TIMESTAMPTZ(timestamp);
+
+	TIME_BUCKET_TS(period, timestamp, result, origin);
+
+	PG_RETURN_TIMESTAMPTZ(result);
+}
+
+static inline void
+check_period_is_daily(int64 period)
+{
+#ifdef HAVE_INT64_TIMESTAMP
+	int64		day = USECS_PER_DAY;
+#else
+	int64		day = SECS_PER_DAY;
+#endif
+	if (period < day)
+	{
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("interval must not have sub-day precision")
+				 ));
+	}
+	if (period % day != 0)
+	{
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("interval must be a multiple of a day")
+				 ));
+
+	}
+}
+
+TS_FUNCTION_INFO_V1(ts_date_bucket);
+
+Datum
+ts_date_bucket(PG_FUNCTION_ARGS)
+{
+	Interval   *interval = PG_GETARG_INTERVAL_P(0);
+	DateADT		date = PG_GETARG_DATEADT(1);
+	Timestamp	origin = DEFAULT_ORIGIN;
+	Timestamp	timestamp,
+				result;
+	int64		period = -1;
+
+	if (DATE_NOT_FINITE(date))
+		PG_RETURN_DATEADT(date);
+
+	period = get_interval_period_timestamp_units(interval);
+	/* check the period aligns on a date */
+	check_period_is_daily(period);
+
+	/* convert to timestamp (NOT tz), bucket, convert back to date */
+	timestamp = DatumGetTimestamp(DirectFunctionCall1(date_timestamp, PG_GETARG_DATUM(1)));
+	if (PG_NARGS() > 2)
+		origin = DatumGetTimestamp(DirectFunctionCall1(date_timestamp, PG_GETARG_DATUM(2)));
+
+	Assert(!TIMESTAMP_NOT_FINITE(timestamp));
+
+	TIME_BUCKET_TS(period, timestamp, result, origin);
+
+	PG_RETURN_DATUM(DirectFunctionCall1(timestamp_date, TimestampGetDatum(result)));
+}