# -*- coding: utf-8 -*-
"""Golang time.Time timestamp implementation."""
import decimal
import struct
from dfdatetime import definitions
from dfdatetime import factory
from dfdatetime import interface
[docs]
class GolangTimeEpoch(interface.DateTimeEpoch):
"""Golang time.Time epoch."""
[docs]
def __init__(self):
"""Initializes a Golang time.Time epoch."""
super(GolangTimeEpoch, self).__init__(1, 1, 1)
[docs]
class GolangTime(interface.DateTimeValues):
"""Golang time.Time timestamp.
A Golang time.Time timestamp contains the number of nanoseconds since
January 1, 1 UTC. Depending on the version of the timestamp, the time
zone is stored in minutes or seconds relative to UTC.
A serialized version 1 Golang time.Time timestamp is a 15 byte value
that consists of:
* byte 0 - version as an 8-bit integer.
* bytes 1-8 - number of seconds since January 1, 1 as a big-endian signed
integer.
* bytes 9-12 - fraction of second, number of nanoseconds as a big-endian
signed integer.
* bytes 13-14 - time zone offset in minutes as a 16-bit big-endian integer,
where -1 represents UTC.
A serialized version 2 Golang time.Time timestamp is a 16 byte value
that consists of:
* byte 0 - version as an 8-bit integer.
* bytes 1-8 - number of seconds since January 1, 1 as a big-endian signed
integer.
* bytes 9-12 - fraction of second, number of nanoseconds as a big-endian
signed integer.
* bytes 13-14 - time zone offset in minutes as a 16-bit big-endian integer,
where -1 represents UTC.
* byte 15 - time zone offset in seconds as an 8-bit integer.
Attributes:
is_local_time (bool): True if the date and time value is in local time
"""
# The delta between January 1, 1970 (unix epoch) and January 1, 1
# (Golang epoch).
_GOLANG_TO_POSIX_BASE = (
((1969 * 365) + (1969 // 4) - (1969 // 100) + (1969 // 400)) *
definitions.SECONDS_PER_DAY)
_EPOCH = GolangTimeEpoch()
[docs]
def __init__(self, golang_timestamp=None, precision=None):
"""Initializes a Golang time.Time timestamp.
Args:
golang_timestamp (Optional[bytes]): the Golang time.Time timestamp.
precision (Optional[str]): precision of the date and time value, which
should be one of the PRECISION_VALUES in definitions.
"""
number_of_seconds, nanoseconds, time_zone_offset = (None, None, None)
if golang_timestamp is not None:
number_of_seconds, nanoseconds, time_zone_offset = (
self._GetNumberOfSeconds(golang_timestamp))
super(GolangTime, self).__init__(
precision=precision or definitions.PRECISION_1_NANOSECOND,
time_zone_offset=time_zone_offset)
self._golang_timestamp = golang_timestamp
self._nanoseconds = nanoseconds
self._number_of_seconds = number_of_seconds
@property
def golang_timestamp(self):
"""int: Golang time.Time timestamp or None if not set."""
return self._golang_timestamp
def _GetNormalizedTimestamp(self):
"""Retrieves the normalized timestamp.
Returns:
decimal.Decimal: normalized timestamp, which contains the number of
seconds since January 1, 1970 00:00:00 and a fraction of second used
for increased precision, or None if the normalized timestamp cannot be
determined.
"""
if self._normalized_timestamp is None:
if (self._number_of_seconds is not None and
self._number_of_seconds >= self._GOLANG_TO_POSIX_BASE and
self._nanoseconds is not None and self._nanoseconds >= 0):
self._normalized_timestamp = decimal.Decimal(
self._number_of_seconds - GolangTime._GOLANG_TO_POSIX_BASE)
if self._nanoseconds is not None and self._nanoseconds >= 0:
self._normalized_timestamp += (
decimal.Decimal(self._nanoseconds) /
definitions.NANOSECONDS_PER_SECOND)
if self._time_zone_offset:
self._normalized_timestamp -= self._time_zone_offset * 60
return self._normalized_timestamp
def _GetNumberOfSeconds(self, golang_timestamp):
"""Retrieves the number of seconds from a Golang time.Time timestamp.
Args:
golang_timestamp (bytes): the Golang time.Time timestamp.
Returns:
tuple[int, int, int]: number of seconds since January 1, 1 00:00:00,
fraction of second in nanoseconds and time zone offset in minutes.
Raises:
ValueError: if the Golang time.Time timestamp could not be parsed.
"""
byte_size = len(golang_timestamp)
if byte_size < 15:
raise ValueError('Unsupported Golang time.Time timestamp.')
version = golang_timestamp[0]
if version not in (1, 2):
raise ValueError(
f'Unsupported Golang time.Time timestamp version: {version:d}.')
if (version == 1 and byte_size != 15) or (version == 2 and byte_size != 16):
raise ValueError('Unsupported Golang time.Time timestamp.')
try:
number_of_seconds, nanoseconds, time_zone_offset = struct.unpack(
'>qih', golang_timestamp[1:15])
# TODO: add support for version 2 time zone offset in seconds
except struct.error as exception:
raise ValueError((
f'Unable to unpacked Golang time.Time timestamp with error: '
f'{exception!s}'))
# A time zone offset of -1 minute is a special representation for UTC.
if time_zone_offset == -1:
time_zone_offset = 0
return number_of_seconds, nanoseconds, time_zone_offset
[docs]
def CopyFromDateTimeString(self, time_string):
"""Copies a date time value from a date and time string.
Args:
time_string (str): date and time value formatted as:
YYYY-MM-DD hh:mm:ss.######[+-]##:##
Where # are numeric digits ranging from 0 to 9 and the seconds
fraction can be either 3, 6 or 9 digits. The time of day, seconds
fraction and time zone offset are optional. The default time zone
is UTC.
Raises:
ValueError: if the time string is invalid or not supported.
"""
date_time_values = self._CopyDateTimeFromString(time_string)
year = date_time_values.get('year', 0)
month = date_time_values.get('month', 0)
day_of_month = date_time_values.get('day_of_month', 0)
hours = date_time_values.get('hours', 0)
minutes = date_time_values.get('minutes', 0)
seconds = date_time_values.get('seconds', 0)
nanoseconds = date_time_values.get('nanoseconds', 0)
time_zone_offset = date_time_values.get('time_zone_offset', None)
if year < 0:
raise ValueError(f'Year value not supported: {year!s}.')
seconds = self._GetNumberOfSecondsFromElements(
year, month, day_of_month, hours, minutes, seconds)
seconds += self._GOLANG_TO_POSIX_BASE
self._normalized_timestamp = None
self._number_of_seconds = seconds
self._nanoseconds = nanoseconds
self._time_zone_offset = time_zone_offset
[docs]
def CopyToDateTimeString(self):
"""Copies the Golang time value to a date and time string.
Returns:
str: date and time value formatted as: "YYYY-MM-DD hh:mm:ss.######" or
None if the timestamp cannot be copied to a date and time string.
"""
if self._number_of_seconds is None or self._number_of_seconds < 0:
return None
number_of_days, hours, minutes, seconds = self._GetTimeValues(
self._number_of_seconds)
year, month, day_of_month = self._GetDateValuesWithEpoch(
number_of_days, self._EPOCH)
return (f'{year:04d}-{month:02d}-{day_of_month:02d} '
f'{hours:02d}:{minutes:02d}:{seconds:02d}.{self._nanoseconds:09d}')
factory.Factory.RegisterDateTimeValues(GolangTime)