-- This file contains utilities for time conversion.
CREATE OR REPLACE FUNCTION _timescaledb_internal.to_microseconds(ts TIMESTAMPTZ) RETURNS BIGINT
	AS '$libdir/timescaledb', 'pg_timestamp_to_microseconds' LANGUAGE C IMMUTABLE STRICT;

CREATE OR REPLACE FUNCTION _timescaledb_internal.to_unix_microseconds(ts TIMESTAMPTZ) RETURNS BIGINT
	AS '$libdir/timescaledb', 'pg_timestamp_to_unix_microseconds' LANGUAGE C IMMUTABLE STRICT;

CREATE OR REPLACE FUNCTION _timescaledb_internal.to_timestamp(unixtime_us BIGINT) RETURNS TIMESTAMPTZ
	AS '$libdir/timescaledb', 'pg_unix_microseconds_to_timestamp' LANGUAGE C IMMUTABLE STRICT;

CREATE OR REPLACE FUNCTION _timescaledb_internal.to_timestamp_pg(postgres_us BIGINT) RETURNS TIMESTAMPTZ
	AS '$libdir/timescaledb', 'pg_microseconds_to_timestamp' LANGUAGE C IMMUTABLE STRICT;


-- Time can be represented in a hypertable as an int* (bigint/integer/smallint) or as a timestamp type (
-- with or without timezones). In or metatables and other internal systems all time values are stored as bigint.
-- Converting from int* columns to internal representation is a cast to bigint.
-- Converting from timestamps to internal representation is conversion to epoch (in microseconds).

-- Gets the sql code for representing the literal for the given time value (in the internal representation) as the column_type.
CREATE OR REPLACE FUNCTION _timescaledb_internal.time_literal_sql(
    time_value      BIGINT,
    column_type     REGTYPE
)
    RETURNS text LANGUAGE PLPGSQL STABLE AS
$BODY$
DECLARE
BEGIN
    IF time_value IS NULL THEN
        RETURN format('%L', NULL);
    END IF;
    CASE column_type
      WHEN 'BIGINT'::regtype, 'INTEGER'::regtype, 'SMALLINT'::regtype THEN
        RETURN format('%L', time_value); -- scale determined by user.
      WHEN 'TIMESTAMP'::regtype, 'TIMESTAMPTZ'::regtype THEN
        -- assume time_value is in microsec
        RETURN format('%2$s %1$L', _timescaledb_internal.to_timestamp(time_value), column_type); -- microseconds
    END CASE;
END
$BODY$;

-- Convert a interval to microseconds.
CREATE OR REPLACE FUNCTION _timescaledb_internal.interval_to_usec(
       chunk_interval INTERVAL
)
RETURNS BIGINT LANGUAGE SQL IMMUTABLE AS
$BODY$
    SELECT (int_sec * 1000000)::bigint from extract(epoch from chunk_interval) as int_sec;
$BODY$;