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from __future__ import annotations
from datetime import datetime, timedelta, tzinfo
from typing import Any, ClassVar, Optional, Sequence
import attrs
from tzlocal import get_localzone
from ...abc import Trigger
from ...marshalling import marshal_date, marshal_timezone, unmarshal_date, unmarshal_timezone
from ...util import timezone_repr
from ...validators import as_aware_datetime, as_timezone, require_state_version
from .fields import (
DEFAULT_VALUES, BaseField, DayOfMonthField, DayOfWeekField, MonthField, WeekField)
@attrs.define(kw_only=True)
class CronTrigger(Trigger):
"""
Triggers when current time matches all specified time constraints, similarly to how the UNIX
cron scheduler works.
:param year: 4-digit year
:param month: month (1-12)
:param day: day of the (1-31)
:param week: ISO week (1-53)
:param day_of_week: number or name of weekday (0-7 or sun,mon,tue,wed,thu,fri,sat,sun)
:param hour: hour (0-23)
:param minute: minute (0-59)
:param second: second (0-59)
:param start_time: earliest possible date/time to trigger on (defaults to current time)
:param end_time: latest possible date/time to trigger on
:param timezone: time zone to use for the date/time calculations
(defaults to the local timezone)
.. note:: The first weekday is always **monday**.
"""
FIELDS_MAP: ClassVar[list[tuple[str, type[BaseField]]]] = [
('year', BaseField),
('month', MonthField),
('day', DayOfMonthField),
('week', WeekField),
('day_of_week', DayOfWeekField),
('hour', BaseField),
('minute', BaseField),
('second', BaseField)
]
year: int | str | None = None
month: int | str | None = None
day: int | str | None = None
week: int | str | None = None
day_of_week: int | str | None = None
hour: int | str | None = None
minute: int | str | None = None
second: int | str | None = None
start_time: datetime = attrs.field(converter=as_aware_datetime, factory=datetime.now)
end_time: datetime | None = None
timezone: tzinfo | str = attrs.field(converter=as_timezone, factory=get_localzone)
_fields: list[BaseField] = attrs.field(init=False, eq=False, factory=list)
_last_fire_time: Optional[datetime] = attrs.field(init=False, eq=False, default=None)
def __attrs_post_init__(self) -> None:
self._set_fields([self.year, self.month, self.day, self.week, self.day_of_week, self.hour,
self.minute, self.second])
self._last_fire_time: Optional[datetime] = None
def _set_fields(self, values: Sequence[int | str | None]) -> None:
self._fields = []
assigned_values = {field_name: value
for (field_name, _), value in zip(self.FIELDS_MAP, values)
if value is not None}
for field_name, field_class in self.FIELDS_MAP:
exprs = assigned_values.pop(field_name, None)
if exprs is None:
exprs = '*' if assigned_values else DEFAULT_VALUES[field_name]
field = field_class(field_name, exprs)
self._fields.append(field)
@classmethod
def from_crontab(cls, expr: str, timezone: str | tzinfo = 'local') -> 'CronTrigger':
"""
Create a :class:`~CronTrigger` from a standard crontab expression.
See https://en.wikipedia.org/wiki/Cron for more information on the format accepted here.
:param expr: minute, hour, day of month, month, day of week
:param timezone: time zone to use for the date/time calculations
(defaults to local timezone if omitted)
"""
values = expr.split()
if len(values) != 5:
raise ValueError(f'Wrong number of fields; got {len(values)}, expected 5')
return cls(minute=values[0], hour=values[1], day=values[2], month=values[3],
day_of_week=values[4], timezone=timezone)
def _increment_field_value(self, dateval: datetime, fieldnum: int) -> tuple[datetime, int]:
"""
Increments the designated field and resets all less significant fields to their minimum
values.
:return: a tuple containing the new date, and the number of the field that was actually
incremented
"""
values = {}
i = 0
while i < len(self._fields):
field = self._fields[i]
if not field.real:
if i == fieldnum:
fieldnum -= 1
i -= 1
else:
i += 1
continue
if i < fieldnum:
values[field.name] = field.get_value(dateval)
i += 1
elif i > fieldnum:
values[field.name] = field.get_min(dateval)
i += 1
else:
value = field.get_value(dateval)
maxval = field.get_max(dateval)
if value == maxval:
fieldnum -= 1
i -= 1
else:
values[field.name] = value + 1
i += 1
difference = datetime(**values) - dateval.replace(tzinfo=None)
dateval = datetime.fromtimestamp(dateval.timestamp() + difference.total_seconds(),
self.timezone)
return dateval, fieldnum
def _set_field_value(self, dateval: datetime, fieldnum: int, new_value: int) -> datetime:
values = {}
for i, field in enumerate(self._fields):
if field.real:
if i < fieldnum:
values[field.name] = field.get_value(dateval)
elif i > fieldnum:
values[field.name] = field.get_min(dateval)
else:
values[field.name] = new_value
return datetime(**values, tzinfo=self.timezone)
def next(self) -> Optional[datetime]:
if self._last_fire_time:
start_time = self._last_fire_time + timedelta(microseconds=1)
else:
start_time = self.start_time
fieldnum = 0
next_time = datetime_ceil(start_time).astimezone(self.timezone)
while 0 <= fieldnum < len(self._fields):
field = self._fields[fieldnum]
curr_value = field.get_value(next_time)
next_value = field.get_next_value(next_time)
if next_value is None:
# No valid value was found
next_time, fieldnum = self._increment_field_value(next_time, fieldnum - 1)
elif next_value > curr_value:
# A valid, but higher than the starting value, was found
if field.real:
next_time = self._set_field_value(next_time, fieldnum, next_value)
fieldnum += 1
else:
next_time, fieldnum = self._increment_field_value(next_time, fieldnum)
else:
# A valid value was found, no changes necessary
fieldnum += 1
# Return if the date has rolled past the end date
if self.end_time and next_time > self.end_time:
return None
if fieldnum >= 0:
self._last_fire_time = next_time
return next_time
def __getstate__(self) -> dict[str, Any]:
return {
'version': 1,
'timezone': marshal_timezone(self.timezone),
'fields': [str(f) for f in self._fields],
'start_time': marshal_date(self.start_time),
'end_time': marshal_date(self.end_time),
'last_fire_time': marshal_date(self._last_fire_time)
}
def __setstate__(self, state: dict[str, Any]) -> None:
require_state_version(self, state, 1)
self.timezone = unmarshal_timezone(state['timezone'])
self.start_time = unmarshal_date(state['start_time'])
self.end_time = unmarshal_date(state['end_time'])
self._last_fire_time = unmarshal_date(state['last_fire_time'])
self._set_fields(state['fields'])
def __repr__(self) -> str:
fields = [f'{field.name}={str(field)!r}' for field in self._fields]
fields.append(f'start_time={self.start_time.isoformat()!r}')
if self.end_time:
fields.append(f'end_time={self.end_time.isoformat()!r}')
fields.append(f'timezone={timezone_repr(self.timezone)!r}')
return f'CronTrigger({", ".join(fields)})'
def datetime_ceil(dateval: datetime) -> datetime:
"""Round the given datetime object upwards."""
if dateval.microsecond > 0:
return dateval + timedelta(seconds=1, microseconds=-dateval.microsecond)
return dateval
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