"""Helpful functions used internally within arrow."""
import datetime
from typing
import Any, Optional, cast
from dateutil.rrule
import WEEKLY, rrule
from arrow.constants
import (
MAX_ORDINAL,
MAX_TIMESTAMP,
MAX_TIMESTAMP_MS,
MAX_TIMESTAMP_US,
MIN_ORDINAL,
)
def next_weekday(
start_date: Optional[datetime.date], weekday: int
) -> datetime.datetime:
"""Get next weekday from the specified start date.
:param start_date: Datetime object representing the start date.
:param weekday: Next weekday to obtain. Can be a value between 0 (Monday)
and 6 (Sunday).
:
return: Datetime object corresponding to the next weekday after start_date.
Usage::
# Get first Monday after epoch
>>> next_weekday(datetime(1970, 1, 1), 0)
1970-01-05 00:00:00
# Get first Thursday after epoch
>>> next_weekday(datetime(1970, 1, 1), 3)
1970-01-01 00:00:00
# Get first Sunday after epoch
>>> next_weekday(datetime(1970, 1, 1), 6)
1970-01-04 00:00:00
"""
if weekday < 0
or weekday > 6:
raise ValueError(
"Weekday must be between 0 (Monday) and 6 (Sunday).")
return cast(
datetime.datetime,
rrule(freq=WEEKLY, dtstart=start_date, byweekday=weekday, count=1)[0],
)
def is_timestamp(value: Any) -> bool:
"""Check if value is a valid timestamp."""
if isinstance(value, bool):
return False
if not isinstance(value, (int, float, str)):
return False
try:
float(value)
return True
except ValueError:
return False
def validate_ordinal(value: Any) ->
None:
"""Raise an exception if value is an invalid Gregorian ordinal.
:param value: the input to be checked
"""
if isinstance(value, bool)
or not isinstance(value, int):
raise TypeError(f
"Ordinal must be an integer (got type {type(value)}).")
if not (MIN_ORDINAL <= value <= MAX_ORDINAL):
raise ValueError(f
"Ordinal {value} is out of range.")
def normalize_timestamp(timestamp: float) -> float:
"""Normalize millisecond and microsecond timestamps into normal timestamps."""
if timestamp > MAX_TIMESTAMP:
if timestamp < MAX_TIMESTAMP_MS:
timestamp /= 1000
elif timestamp < MAX_TIMESTAMP_US:
timestamp /= 1_000_000
else:
raise ValueError(f
"The specified timestamp {timestamp!r} is too large.")
return timestamp
# Credit to https://stackoverflow.com/a/1700069
def iso_to_gregorian(iso_year: int, iso_week: int, iso_day: int) -> datetime.date:
"""Converts an ISO week date into a datetime object.
:param iso_year: the year
:param iso_week: the week number, each year has either 52
or 53 weeks
:param iso_day: the day numbered 1 through 7, beginning
with Monday
"""
if not 1 <= iso_week <= 53:
raise ValueError(
"ISO Calendar week value must be between 1-53.")
if not 1 <= iso_day <= 7:
raise ValueError(
"ISO Calendar day value must be between 1-7")
# The first week of the year always contains 4 Jan.
fourth_jan = datetime.date(iso_year, 1, 4)
delta = datetime.timedelta(fourth_jan.isoweekday() - 1)
year_start = fourth_jan - delta
gregorian = year_start + datetime.timedelta(days=iso_day - 1, weeks=iso_week - 1)
return gregorian
def validate_bounds(bounds: str) ->
None:
if bounds !=
"()" and bounds !=
"(]" and bounds !=
"[)" and bounds !=
"[]":
raise ValueError(
"Invalid bounds. Please select between '()', '(]', '[)', or '[]'."
)
__all__ = [
"next_weekday",
"is_timestamp",
"validate_ordinal",
"iso_to_gregorian"]
