Files
osxphotos/osxphotos/datetime_utils.py
2020-12-05 07:18:49 -08:00

162 lines
4.4 KiB
Python

""" datetime.datetime helper functions for converting to/from UTC """
import datetime
def get_local_tz(dt):
""" Return local timezone as datetime.timezone tzinfo for dt
Args:
dt: datetime.datetime
Returns:
local timezone for dt as datetime.timezone
Raises:
ValueError if dt is not timezone naive
"""
if not datetime_has_tz(dt):
return dt.astimezone().tzinfo
else:
raise ValueError("dt must be naive datetime.datetime object")
def datetime_has_tz(dt):
""" Return True if datetime dt has tzinfo else False
Args:
dt: datetime.datetime
Returns:
True if dt is timezone aware, else False
Raises:
TypeError if dt is not a datetime.datetime object
"""
if type(dt) != datetime.datetime:
raise TypeError(f"dt must be type datetime.datetime, not {type(dt)}")
return dt.tzinfo is not None and dt.tzinfo.utcoffset(dt) is not None
def datetime_tz_to_utc(dt):
""" Convert datetime.datetime object with timezone to UTC timezone
Args:
dt: datetime.datetime object
Returns:
datetime.datetime in UTC timezone
Raises:
TypeError if dt is not datetime.datetime object
ValueError if dt does not have timeone information
"""
if type(dt) != datetime.datetime:
raise TypeError(f"dt must be type datetime.datetime, not {type(dt)}")
if dt.tzinfo is not None and dt.tzinfo.utcoffset(dt) is not None:
return dt.replace(tzinfo=dt.tzinfo).astimezone(tz=datetime.timezone.utc)
else:
raise ValueError(f"dt does not have timezone info")
def datetime_remove_tz(dt):
""" Remove timezone from a datetime.datetime object
Args:
dt: datetime.datetime object with tzinfo
Returns:
dt without any timezone info (naive datetime object)
Raises:
TypeError if dt is not a datetime.datetime object
"""
if type(dt) != datetime.datetime:
raise TypeError(f"dt must be type datetime.datetime, not {type(dt)}")
return dt.replace(tzinfo=None)
def datetime_naive_to_utc(dt):
""" Convert naive (timezone unaware) datetime.datetime
to aware timezone in UTC timezone
Args:
dt: datetime.datetime without timezone
Returns:
datetime.datetime with UTC timezone
Raises:
TypeError if dt is not a datetime.datetime object
ValueError if dt is not a naive/timezone unaware object
"""
if type(dt) != datetime.datetime:
raise TypeError(f"dt must be type datetime.datetime, not {type(dt)}")
if dt.tzinfo is not None and dt.tzinfo.utcoffset(dt) is not None:
# has timezone info
raise ValueError(
"dt must be naive/timezone unaware: "
f"{dt} has tzinfo {dt.tzinfo} and offset {dt.tzinfo.utcoffset(dt)}"
)
return dt.replace(tzinfo=datetime.timezone.utc)
def datetime_naive_to_local(dt):
""" Convert naive (timezone unaware) datetime.datetime
to aware timezone in local timezone
Args:
dt: datetime.datetime without timezone
Returns:
datetime.datetime with local timezone
Raises:
TypeError if dt is not a datetime.datetime object
ValueError if dt is not a naive/timezone unaware object
"""
if type(dt) != datetime.datetime:
raise TypeError(f"dt must be type datetime.datetime, not {type(dt)}")
if dt.tzinfo is not None and dt.tzinfo.utcoffset(dt) is not None:
# has timezone info
raise ValueError(
"dt must be naive/timezone unaware: "
f"{dt} has tzinfo {dt.tzinfo} and offset {dt.tizinfo.utcoffset(dt)}"
)
return dt.replace(tzinfo=get_local_tz(dt))
def datetime_utc_to_local(dt):
""" Convert datetime.datetime object in UTC timezone to local timezone
Args:
dt: datetime.datetime object
Returns:
datetime.datetime in local timezone
Raises:
TypeError if dt is not a datetime.datetime object
ValueError if dt is not in UTC timezone
"""
if type(dt) != datetime.datetime:
raise TypeError(f"dt must be type datetime.datetime, not {type(dt)}")
if dt.tzinfo is not datetime.timezone.utc:
raise ValueError(f"{dt} must be in UTC timezone: timezone = {dt.tzinfo}")
return dt.replace(tzinfo=datetime.timezone.utc).astimezone(tz=None)