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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
import re
import sys
from typing import Any, cast
import ciso8601
from homeassistant.const import MATCH_ALL
if sys.version_info[:2] >= (3, 9):
import zoneinfo
from backports import zoneinfo
DATE_STR_FORMAT = "%Y-%m-%d"
UTC = dt.timezone.utc
DEFAULT_TIME_ZONE: dt.tzinfo = dt.timezone.utc
# Copyright (c) Django Software Foundation and individual contributors.
# All rights reserved.
DATETIME_RE = re.compile(
r"[T ](?P<hour>\d{1,2}):(?P<minute>\d{1,2})"
def set_default_time_zone(time_zone: dt.tzinfo) -> None:
"""Set a default time zone to be used when none is specified.
Async friendly.
global DEFAULT_TIME_ZONE # pylint: disable=global-statement
assert isinstance(time_zone, dt.tzinfo)
def get_time_zone(time_zone_str: str) -> dt.tzinfo | None:
"""Get time zone from string. Return None if unable to determine.
Async friendly.
# Cast can be removed when mypy is switched to Python 3.9.
return cast(dt.tzinfo, zoneinfo.ZoneInfo(time_zone_str))
except zoneinfo.ZoneInfoNotFoundError:
return None
def utcnow() -> dt.datetime:
"""Get now in UTC time."""
def now(time_zone: dt.tzinfo | None = None) -> dt.datetime:
"""Get now in specified 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
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)
def utc_from_timestamp(timestamp: float) -> dt.datetime:
"""Return a UTC time from a timestamp."""
return dt.datetime.utcfromtimestamp(timestamp).replace(tzinfo=UTC)
def start_of_local_day(dt_or_d: | 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: = now().date()
elif isinstance(dt_or_d, dt.datetime):
date =
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.
def parse_datetime(dt_str: str) -> 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.
Returns None if the input isn't well formatted.
with suppress(ValueError, IndexError):
return ciso8601.parse_datetime(dt_str)
match = DATETIME_RE.match(dt_str)
if not match:
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) -> | None:
"""Convert a date string to a date object."""
return dt.datetime.strptime(dt_str, DATE_STR_FORMAT).date()
except ValueError: # If dt_str did not match our format
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
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_age(date: dt.datetime) -> str:
Take a datetime and return its "age" as a string.
The age can be in second, minute, hour, day, month or year. Only the
biggest unit is considered, e.g. if it's 2 days and 3 hours, "2 days" will
be returned.
Make sure date is not in the future, or else it won't work.
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"
delta = (now() - date).total_seconds()
rounded_delta = round(delta)
units = ["second", "minute", "hour", "day", "month"]
factors = [60, 60, 24, 30, 12]
selected_unit = "year"
for i, next_factor in enumerate(factors):
if rounded_delta < next_factor:
selected_unit = units[i]
delta /= next_factor
rounded_delta = round(delta)
return formatn(rounded_delta, selected_unit)
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 == MATCH_ALL:
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]
res = [int(parameter)]
elif not hasattr(parameter, "__iter__"):
res = [int(parameter)]
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() - (dattim - delta).utcoffset() # type: ignore[operator]
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!")
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.
left = bisect.bisect_left(arr, cmp)
if left == len(arr):
return None
return arr[left]
result = now.replace(microsecond=0)
# Match next second
next_second = _lower_bound(seconds, result.second)
if next_second is None:
# No second to match in this minute. Roll-over to next minute.
next_second = seconds[0]
result += dt.timedelta(minutes=1)
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)
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)
result = result.replace(hour=next_hour)
if result.tzinfo in (None, UTC):
return result
if _datetime_ambiguous(result):
# This happens when we're leaving daylight saving time and local
# clocks are rolled back. In this case, we want to trigger
# on both the DST and non-DST time. So when "now" is in the DST
# use the DST-on time, and if not, use the DST-off time.
fold = 1 if now.dst() else 0
if result.fold != fold:
result = result.replace(fold=fold)
if not _datetime_exists(result):
# This happens when we're entering daylight saving time and local
# clocks are rolled forward, thus there are local times that do
# not exist. In this case, we want to trigger on the next time
# that *does* exist.
# In the worst case, this will run through all the seconds in the
# time shift, but that's max 3600 operations for once per year
return find_next_time_expression_time(
result + dt.timedelta(seconds=1), seconds, minutes, hours
# Another edge-case when leaving DST:
# When now is in DST and ambiguous *and* the next trigger time we *should*
# trigger is ambiguous and outside DST, the excepts above won't catch it.
# For example: if triggering on 2:30 and now is 28.10.2018 2:30 (in DST)
# we should trigger next on 28.10.2018 2:30 (out of DST), but our
# algorithm above would produce 29.10.2018 2:30 (out of DST)
if _datetime_ambiguous(now):
check_result = find_next_time_expression_time(
now + _dst_offset_diff(now), seconds, minutes, hours
if _datetime_ambiguous(check_result):
return check_result
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()