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core/homeassistant/util/dt.py

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"""Helper methods to handle the time in Home Assistant."""
from __future__ import annotations
import bisect
from contextlib import suppress
import datetime as dt
from functools import lru_cache, partial
import re
from typing import Any, Literal, overload
import zoneinfo
from aiozoneinfo import async_get_time_zone as _async_get_time_zone
import ciso8601
from homeassistant.helpers.deprecation import deprecated_function
DATE_STR_FORMAT = "%Y-%m-%d"
UTC = dt.UTC
DEFAULT_TIME_ZONE: dt.tzinfo = dt.UTC
# EPOCHORDINAL is not exposed as a constant
# https://github.com/python/cpython/blob/3.10/Lib/zoneinfo/_zoneinfo.py#L12
EPOCHORDINAL = dt.datetime(1970, 1, 1).toordinal()
# Copyright (c) Django Software Foundation and individual contributors.
# All rights reserved.
# https://github.com/django/django/blob/main/LICENSE
DATETIME_RE = re.compile(
r"(?P<year>\d{4})-(?P<month>\d{1,2})-(?P<day>\d{1,2})"
r"[T ](?P<hour>\d{1,2}):(?P<minute>\d{1,2})"
r"(?::(?P<second>\d{1,2})(?:\.(?P<microsecond>\d{1,6})\d{0,6})?)?"
r"(?P<tzinfo>Z|[+-]\d{2}(?::?\d{2})?)?$"
)
# Copyright (c) Django Software Foundation and individual contributors.
# All rights reserved.
# https://github.com/django/django/blob/main/LICENSE
STANDARD_DURATION_RE = re.compile(
r"^"
r"(?:(?P<days>-?\d+) (days?, )?)?"
r"(?P<sign>-?)"
r"((?:(?P<hours>\d+):)(?=\d+:\d+))?"
r"(?:(?P<minutes>\d+):)?"
r"(?P<seconds>\d+)"
r"(?:[\.,](?P<microseconds>\d{1,6})\d{0,6})?"
r"$"
)
# Copyright (c) Django Software Foundation and individual contributors.
# All rights reserved.
# https://github.com/django/django/blob/main/LICENSE
ISO8601_DURATION_RE = re.compile(
r"^(?P<sign>[-+]?)"
r"P"
r"(?:(?P<days>\d+([\.,]\d+)?)D)?"
r"(?:T"
r"(?:(?P<hours>\d+([\.,]\d+)?)H)?"
r"(?:(?P<minutes>\d+([\.,]\d+)?)M)?"
r"(?:(?P<seconds>\d+([\.,]\d+)?)S)?"
r")?"
r"$"
)
# Copyright (c) Django Software Foundation and individual contributors.
# All rights reserved.
# https://github.com/django/django/blob/main/LICENSE
POSTGRES_INTERVAL_RE = re.compile(
r"^"
r"(?:(?P<days>-?\d+) (days? ?))?"
r"(?:(?P<sign>[-+])?"
r"(?P<hours>\d+):"
r"(?P<minutes>\d\d):"
r"(?P<seconds>\d\d)"
r"(?:\.(?P<microseconds>\d{1,6}))?"
r")?$"
)
@lru_cache(maxsize=1)
def get_default_time_zone() -> dt.tzinfo:
"""Get the default time zone."""
return DEFAULT_TIME_ZONE
def set_default_time_zone(time_zone: dt.tzinfo) -> None:
"""Set a default time zone to be used when none is specified.
Async friendly.
"""
# pylint: disable-next=global-statement
global DEFAULT_TIME_ZONE # noqa: PLW0603
assert isinstance(time_zone, dt.tzinfo)
DEFAULT_TIME_ZONE = time_zone
get_default_time_zone.cache_clear()
def get_time_zone(time_zone_str: str) -> zoneinfo.ZoneInfo | None:
"""Get time zone from string. Return None if unable to determine.
Must be run in the executor if the ZoneInfo is not already
in the cache. If you are not sure, use async_get_time_zone.
"""
try:
return zoneinfo.ZoneInfo(time_zone_str)
except zoneinfo.ZoneInfoNotFoundError:
return None
async def async_get_time_zone(time_zone_str: str) -> zoneinfo.ZoneInfo | None:
"""Get time zone from string. Return None if unable to determine.
Async friendly.
"""
try:
return await _async_get_time_zone(time_zone_str)
except zoneinfo.ZoneInfoNotFoundError:
return None
# We use a partial here since it is implemented in native code
# and avoids the global lookup of UTC
utcnow = partial(dt.datetime.now, UTC)
utcnow.__doc__ = "Get now in UTC time."
def now(time_zone: dt.tzinfo | None = None) -> dt.datetime:
"""Get now in specified time zone."""
return dt.datetime.now(time_zone or DEFAULT_TIME_ZONE)
def as_utc(dattim: dt.datetime) -> dt.datetime:
"""Return a datetime as UTC time.
Assumes datetime without tzinfo to be in the DEFAULT_TIME_ZONE.
"""
if dattim.tzinfo == UTC:
return dattim
if dattim.tzinfo is None:
dattim = dattim.replace(tzinfo=DEFAULT_TIME_ZONE)
return dattim.astimezone(UTC)
def as_timestamp(dt_value: dt.datetime | str) -> float:
"""Convert a date/time into a unix time (seconds since 1970)."""
parsed_dt: dt.datetime | None
if isinstance(dt_value, dt.datetime):
parsed_dt = dt_value
else:
parsed_dt = parse_datetime(str(dt_value))
if parsed_dt is None:
raise ValueError("not a valid date/time.")
return parsed_dt.timestamp()
def as_local(dattim: dt.datetime) -> dt.datetime:
"""Convert a UTC datetime object to local time zone."""
if dattim.tzinfo == DEFAULT_TIME_ZONE:
return dattim
if dattim.tzinfo is None:
dattim = dattim.replace(tzinfo=DEFAULT_TIME_ZONE)
return dattim.astimezone(DEFAULT_TIME_ZONE)
# We use a partial here to improve performance by avoiding the global lookup
# of UTC and the function call overhead.
utc_from_timestamp = partial(dt.datetime.fromtimestamp, tz=UTC)
"""Return a UTC time from a timestamp."""
@deprecated_function("datetime.timestamp", breaks_in_ha_version="2026.1")
def utc_to_timestamp(utc_dt: dt.datetime) -> float:
"""Fast conversion of a datetime in UTC to a timestamp."""
# Taken from
# https://github.com/python/cpython/blob/3.10/Lib/zoneinfo/_zoneinfo.py#L185
return (
(utc_dt.toordinal() - EPOCHORDINAL) * 86400
+ utc_dt.hour * 3600
+ utc_dt.minute * 60
+ utc_dt.second
+ (utc_dt.microsecond / 1000000)
)
def start_of_local_day(dt_or_d: dt.date | dt.datetime | None = None) -> dt.datetime:
"""Return local datetime object of start of day from date or datetime."""
if dt_or_d is None:
date: dt.date = now().date()
elif isinstance(dt_or_d, dt.datetime):
date = dt_or_d.date()
else:
date = dt_or_d
return dt.datetime.combine(date, dt.time(), tzinfo=DEFAULT_TIME_ZONE)
# Copyright (c) Django Software Foundation and individual contributors.
# All rights reserved.
# https://github.com/django/django/blob/main/LICENSE
@overload
def parse_datetime(dt_str: str) -> dt.datetime | None: ...
@overload
def parse_datetime(dt_str: str, *, raise_on_error: Literal[True]) -> dt.datetime: ...
@overload
def parse_datetime(
dt_str: str, *, raise_on_error: Literal[False]
) -> dt.datetime | None: ...
def parse_datetime(dt_str: str, *, raise_on_error: bool = False) -> dt.datetime | None:
"""Parse a string and return a datetime.datetime.
This function supports time zone offsets. When the input contains one,
the output uses a timezone with a fixed offset from UTC.
Raises ValueError if the input is well formatted but not a valid datetime.
If the input isn't well formatted, returns None if raise_on_error is False
or raises ValueError if it's True.
"""
# First try if the string can be parsed by the fast ciso8601 library
with suppress(ValueError, IndexError):
return ciso8601.parse_datetime(dt_str)
# ciso8601 failed to parse the string, fall back to regex
if not (match := DATETIME_RE.match(dt_str)):
if raise_on_error:
raise ValueError
return None
kws: dict[str, Any] = match.groupdict()
if kws["microsecond"]:
kws["microsecond"] = kws["microsecond"].ljust(6, "0")
tzinfo_str = kws.pop("tzinfo")
tzinfo: dt.tzinfo | None = None
if tzinfo_str == "Z":
tzinfo = UTC
elif tzinfo_str is not None:
offset_mins = int(tzinfo_str[-2:]) if len(tzinfo_str) > 3 else 0
offset_hours = int(tzinfo_str[1:3])
offset = dt.timedelta(hours=offset_hours, minutes=offset_mins)
if tzinfo_str[0] == "-":
offset = -offset
tzinfo = dt.timezone(offset)
kws = {k: int(v) for k, v in kws.items() if v is not None}
kws["tzinfo"] = tzinfo
return dt.datetime(**kws)
def parse_date(dt_str: str) -> dt.date | None:
"""Convert a date string to a date object."""
try:
return dt.datetime.strptime(dt_str, DATE_STR_FORMAT).date()
except ValueError: # If dt_str did not match our format
return None
# Copyright (c) Django Software Foundation and individual contributors.
# All rights reserved.
# https://github.com/django/django/blob/master/LICENSE
def parse_duration(value: str) -> dt.timedelta | None:
"""Parse a duration string and return a datetime.timedelta.
Also supports ISO 8601 representation and PostgreSQL's day-time interval
format.
"""
match = (
STANDARD_DURATION_RE.match(value)
or ISO8601_DURATION_RE.match(value)
or POSTGRES_INTERVAL_RE.match(value)
)
if match:
kws = match.groupdict()
sign = -1 if kws.pop("sign", "+") == "-" else 1
if kws.get("microseconds"):
kws["microseconds"] = kws["microseconds"].ljust(6, "0")
time_delta_args: dict[str, float] = {
k: float(v.replace(",", ".")) for k, v in kws.items() if v is not None
}
days = dt.timedelta(float(time_delta_args.pop("days", 0.0) or 0.0))
if match.re == ISO8601_DURATION_RE:
days *= sign
return days + sign * dt.timedelta(**time_delta_args)
return None
def parse_time(time_str: str) -> dt.time | None:
"""Parse a time string (00:20:00) into Time object.
Return None if invalid.
"""
parts = str(time_str).split(":")
if len(parts) < 2:
return None
try:
hour = int(parts[0])
minute = int(parts[1])
second = int(parts[2]) if len(parts) > 2 else 0
return dt.time(hour, minute, second)
except ValueError:
# ValueError if value cannot be converted to an int or not in range
return None
def _get_timestring(timediff: float, precision: int = 1) -> str:
"""Return a string representation of a time diff."""
def formatn(number: int, unit: str) -> str:
"""Add "unit" if it's plural."""
if number == 1:
return f"1 {unit} "
return f"{number:d} {unit}s "
if timediff == 0.0:
return "0 seconds"
units = ("year", "month", "day", "hour", "minute", "second")
factors = (365 * 24 * 60 * 60, 30 * 24 * 60 * 60, 24 * 60 * 60, 60 * 60, 60, 1)
result_string: str = ""
current_precision = 0
for i, current_factor in enumerate(factors):
selected_unit = units[i]
if timediff < current_factor:
continue
current_precision = current_precision + 1
if current_precision == precision:
return (
result_string + formatn(round(timediff / current_factor), selected_unit)
).rstrip()
curr_diff = int(timediff // current_factor)
result_string += formatn(curr_diff, selected_unit)
timediff -= (curr_diff) * current_factor
return result_string.rstrip()
def get_age(date: dt.datetime, precision: int = 1) -> str:
"""Take a datetime and return its "age" as a string.
The age can be in second, minute, hour, day, month and year.
depth number of units will be returned, with the last unit rounded
The date must be in the past or a ValueException will be raised.
"""
delta = (now() - date).total_seconds()
rounded_delta = round(delta)
if rounded_delta < 0:
raise ValueError("Time value is in the future")
return _get_timestring(rounded_delta, precision)
def get_time_remaining(date: dt.datetime, precision: int = 1) -> str:
"""Take a datetime and return its "age" as a string.
The age can be in second, minute, hour, day, month and year.
depth number of units will be returned, with the last unit rounded
The date must be in the future or a ValueException will be raised.
"""
delta = (date - now()).total_seconds()
rounded_delta = round(delta)
if rounded_delta < 0:
raise ValueError("Time value is in the past")
return _get_timestring(rounded_delta, precision)
def parse_time_expression(parameter: Any, min_value: int, max_value: int) -> list[int]:
"""Parse the time expression part and return a list of times to match."""
if parameter is None or parameter == "*":
res = list(range(min_value, max_value + 1))
elif isinstance(parameter, str):
if parameter.startswith("/"):
parameter = int(parameter[1:])
res = [x for x in range(min_value, max_value + 1) if x % parameter == 0]
else:
res = [int(parameter)]
elif not hasattr(parameter, "__iter__"):
res = [int(parameter)]
else:
res = sorted(int(x) for x in parameter)
for val in res:
if val < min_value or val > max_value:
raise ValueError(
f"Time expression '{parameter}': parameter {val} out of range "
f"({min_value} to {max_value})"
)
return res
def _dst_offset_diff(dattim: dt.datetime) -> dt.timedelta:
"""Return the offset when crossing the DST barrier."""
delta = dt.timedelta(hours=24)
return (dattim + delta).utcoffset() - ( # type: ignore[operator]
dattim - delta
).utcoffset()
def _lower_bound(arr: list[int], cmp: int) -> int | None:
"""Return the first value in arr greater or equal to cmp.
Return None if no such value exists.
"""
if (left := bisect.bisect_left(arr, cmp)) == len(arr):
return None
return arr[left]
def find_next_time_expression_time(
now: dt.datetime, # pylint: disable=redefined-outer-name
seconds: list[int],
minutes: list[int],
hours: list[int],
) -> dt.datetime:
"""Find the next datetime from now for which the time expression matches.
The algorithm looks at each time unit separately and tries to find the
next one that matches for each. If any of them would roll over, all
time units below that are reset to the first matching value.
Timezones are also handled (the tzinfo of the now object is used),
including daylight saving time.
"""
if not seconds or not minutes or not hours:
raise ValueError("Cannot find a next time: Time expression never matches!")
while True:
# Reset microseconds and fold; fold (for ambiguous DST times) will be
# handled later.
result = now.replace(microsecond=0, fold=0)
# Match next second
if (next_second := _lower_bound(seconds, result.second)) is None:
# No second to match in this minute. Roll-over to next minute.
next_second = seconds[0]
result += dt.timedelta(minutes=1)
if result.second != next_second:
result = result.replace(second=next_second)
# Match next minute
next_minute = _lower_bound(minutes, result.minute)
if next_minute != result.minute:
# We're in the next minute. Seconds needs to be reset.
result = result.replace(second=seconds[0])
if next_minute is None:
# No minute to match in this hour. Roll-over to next hour.
next_minute = minutes[0]
result += dt.timedelta(hours=1)
if result.minute != next_minute:
result = result.replace(minute=next_minute)
# Match next hour
next_hour = _lower_bound(hours, result.hour)
if next_hour != result.hour:
# We're in the next hour. Seconds+minutes needs to be reset.
result = result.replace(second=seconds[0], minute=minutes[0])
if next_hour is None:
# No minute to match in this day. Roll-over to next day.
next_hour = hours[0]
result += dt.timedelta(days=1)
if result.hour != next_hour:
result = result.replace(hour=next_hour)
if result.tzinfo in (None, UTC):
# Using UTC, no DST checking needed
return result
if not _datetime_exists(result):
# When entering DST and clocks are turned forward.
# There are wall clock times that don't "exist" (an hour is skipped).
# -> trigger on the next time that 1. matches the pattern and 2. does exist
# for example:
# on 2021.03.28 02:00:00 in CET timezone clocks are turned forward an hour
# with pattern "02:30", don't run on 28 mar (such a wall time does not
# exist on this day) instead run at 02:30 the next day
# We solve this edge case by just iterating one second until the result
# exists (max. 3600 operations, which should be fine for an edge case that
# happens once a year)
now += dt.timedelta(seconds=1)
continue
if not _datetime_ambiguous(now):
return result
# When leaving DST and clocks are turned backward.
# Then there are wall clock times that are ambiguous i.e. exist with DST and
# without DST. The logic above does not take into account if a given pattern
# matches _twice_ in a day.
# Example: on 2021.10.31 02:00:00 in CET timezone clocks are turned
# backward an hour.
if _datetime_ambiguous(result):
# `now` and `result` are both ambiguous, so the next match happens
# _within_ the current fold.
# Examples:
# 1. 2021.10.31 02:00:00+02:00 with pattern 02:30
# -> 2021.10.31 02:30:00+02:00
# 2. 2021.10.31 02:00:00+01:00 with pattern 02:30
# -> 2021.10.31 02:30:00+01:00
return result.replace(fold=now.fold)
if now.fold == 0:
# `now` is in the first fold, but result is not ambiguous (meaning it no
# longer matches within the fold).
# -> Check if result matches in the next fold. If so, emit that match
# Turn back the time by the DST offset, effectively run the algorithm on
# the first fold. If it matches on the first fold, that means it will also
# match on the second one.
# Example: 2021.10.31 02:45:00+02:00 with pattern 02:30
# -> 2021.10.31 02:30:00+01:00
check_result = find_next_time_expression_time(
now + _dst_offset_diff(now), seconds, minutes, hours
)
if _datetime_ambiguous(check_result):
return check_result.replace(fold=1)
return result
def _datetime_exists(dattim: dt.datetime) -> bool:
"""Check if a datetime exists."""
assert dattim.tzinfo is not None
original_tzinfo = dattim.tzinfo
# Check if we can round trip to UTC
return dattim == dattim.astimezone(UTC).astimezone(original_tzinfo)
def _datetime_ambiguous(dattim: dt.datetime) -> bool:
"""Check whether a datetime is ambiguous."""
assert dattim.tzinfo is not None
opposite_fold = dattim.replace(fold=not dattim.fold)
return _datetime_exists(dattim) and dattim.utcoffset() != opposite_fold.utcoffset()
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