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# -*- coding: utf-8 -*-
# Copyright 2025 Mike Fährmann
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License version 2 as
# published by the Free Software Foundation.
"""Date/Time utilities"""
import sys
import time
from datetime import datetime, date, timedelta, timezone # noqa F401
class NullDatetime(datetime):
def __bool__(self):
return False
def __str__(self):
return "[Invalid DateTime]"
def __format__(self, format_spec):
return "[Invalid DateTime]"
NONE = NullDatetime(1, 1, 1)
EPOCH = datetime(1970, 1, 1)
SECOND = timedelta(0, 1)
def normalize(dt):
# if (o := dt.utcoffset()) is not None:
# return dt.replace(tzinfo=None, microsecond=0) - o
if dt.tzinfo is not None:
return dt.astimezone(timezone.utc).replace(tzinfo=None, microsecond=0)
if dt.microsecond:
return dt.replace(microsecond=0)
return dt
def convert(value):
"""Convert 'value' to a naive UTC datetime object"""
if not value:
return NONE
if isinstance(value, datetime):
return normalize(value)
if isinstance(value, str) and (dt := parse_iso(value)) is not NONE:
return dt
return parse_ts(value)
def parse(dt_string, format):
"""Parse 'dt_string' according to 'format'"""
try:
return normalize(datetime.strptime(dt_string, format))
except Exception:
return NONE
if sys.hexversion < 0x30c0000:
# Python <= 3.11
def parse_iso(dt_string):
"""Parse 'dt_string' as ISO 8601 value"""
try:
if dt_string[-1] == "Z":
# compat for Python < 3.11
dt_string = dt_string[:-1]
elif dt_string[-5] in "+-":
# compat for Python < 3.11
dt_string = f"{dt_string[:-2]}:{dt_string[-2:]}"
return normalize(datetime.fromisoformat(dt_string))
except Exception:
return NONE
from_ts = datetime.utcfromtimestamp
now = datetime.utcnow
else:
# Python >= 3.12
def parse_iso(dt_string):
"""Parse 'dt_string' as ISO 8601 value"""
try:
return normalize(datetime.fromisoformat(dt_string))
except Exception:
return NONE
def from_ts(ts=None):
"""Convert Unix timestamp to naive UTC datetime"""
Y, m, d, H, M, S, _, _, _ = time.gmtime(ts)
return datetime(Y, m, d, H, M, S)
now = from_ts
def parse_ts(ts, default=NONE):
"""Create a datetime object from a Unix timestamp"""
try:
return from_ts(int(ts))
except Exception:
return default
def to_ts(dt):
"""Convert naive UTC datetime to Unix timestamp"""
return (dt - EPOCH) / SECOND
def to_ts_string(dt):
"""Convert naive UTC datetime to Unix timestamp string"""
try:
return str((dt - EPOCH) // SECOND)
except Exception:
return ""
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