292 lines
11 KiB
Python
292 lines
11 KiB
Python
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# -*- coding: utf-8 -*-
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import calendar
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import math
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from datetime import date, datetime, time
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from typing import Tuple, TypeVar, Literal, Iterator, Type
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import babel
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import pytz
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from dateutil.relativedelta import relativedelta, weekdays
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from .func import lazy
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D = TypeVar('D', date, datetime)
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__all__ = [
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'date_range',
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'get_fiscal_year',
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'get_month',
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'get_quarter',
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'get_quarter_number',
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'get_timedelta',
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]
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def date_type(value: D) -> Type[D]:
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''' Return either the datetime.datetime class or datetime.date type whether `value` is a datetime or a date.
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:param value: A datetime.datetime or datetime.date object.
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:return: datetime.datetime or datetime.date
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'''
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return datetime if isinstance(value, datetime) else date
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def get_month(date: D) -> Tuple[D, D]:
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''' Compute the month dates range on which the 'date' parameter belongs to.
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'''
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return date.replace(day=1), date.replace(day=calendar.monthrange(date.year, date.month)[1])
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def get_quarter_number(date: date) -> int:
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''' Get the number of the quarter on which the 'date' parameter belongs to.
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'''
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return math.ceil(date.month / 3)
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def get_quarter(date: D) -> Tuple[D, D]:
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''' Compute the quarter dates range on which the 'date' parameter belongs to.
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'''
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quarter_number = get_quarter_number(date)
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month_from = ((quarter_number - 1) * 3) + 1
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date_from = date.replace(month=month_from, day=1)
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date_to = date_from + relativedelta(months=2)
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date_to = date_to.replace(day=calendar.monthrange(date_to.year, date_to.month)[1])
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return date_from, date_to
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def get_fiscal_year(date: D, day: int = 31, month: int = 12) -> Tuple[D, D]:
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''' Compute the fiscal year dates range on which the 'date' parameter belongs to.
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A fiscal year is the period used by governments for accounting purposes and vary between countries.
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By default, calling this method with only one parameter gives the calendar year because the ending date of the
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fiscal year is set to the YYYY-12-31.
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:param date: A date belonging to the fiscal year
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:param day: The day of month the fiscal year ends.
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:param month: The month of year the fiscal year ends.
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:return: The start and end dates of the fiscal year.
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'''
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def fix_day(year, month, day):
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max_day = calendar.monthrange(year, month)[1]
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if month == 2 and day in (28, max_day):
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return max_day
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return min(day, max_day)
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date_to = date.replace(month=month, day=fix_day(date.year, month, day))
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if date <= date_to:
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date_from = date_to - relativedelta(years=1)
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day = fix_day(date_from.year, date_from.month, date_from.day)
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date_from = date_from.replace(day=day)
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date_from += relativedelta(days=1)
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else:
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date_from = date_to + relativedelta(days=1)
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date_to = date_to + relativedelta(years=1)
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day = fix_day(date_to.year, date_to.month, date_to.day)
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date_to = date_to.replace(day=day)
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return date_from, date_to
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def get_timedelta(qty: int, granularity: Literal['hour', 'day', 'week', 'month', 'year']):
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""" Helper to get a `relativedelta` object for the given quantity and interval unit.
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"""
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switch = {
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'hour': relativedelta(hours=qty),
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'day': relativedelta(days=qty),
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'week': relativedelta(weeks=qty),
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'month': relativedelta(months=qty),
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'year': relativedelta(years=qty),
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}
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return switch[granularity]
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Granularity = Literal['year', 'quarter', 'month', 'week', 'day', 'hour']
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def start_of(value: D, granularity: Granularity) -> D:
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"""
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Get start of a time period from a date or a datetime.
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:param value: initial date or datetime.
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:param granularity: type of period in string, can be year, quarter, month, week, day or hour.
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:return: a date/datetime object corresponding to the start of the specified period.
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"""
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is_datetime = isinstance(value, datetime)
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if granularity == "year":
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result = value.replace(month=1, day=1)
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elif granularity == "quarter":
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# Q1 = Jan 1st
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# Q2 = Apr 1st
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# Q3 = Jul 1st
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# Q4 = Oct 1st
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result = get_quarter(value)[0]
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elif granularity == "month":
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result = value.replace(day=1)
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elif granularity == 'week':
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# `calendar.weekday` uses ISO8601 for start of week reference, this means that
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# by default MONDAY is the first day of the week and SUNDAY is the last.
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result = value - relativedelta(days=calendar.weekday(value.year, value.month, value.day))
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elif granularity == "day":
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result = value
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elif granularity == "hour" and is_datetime:
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return datetime.combine(value, time.min).replace(hour=value.hour)
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elif is_datetime:
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raise ValueError(
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"Granularity must be year, quarter, month, week, day or hour for value %s" % value
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)
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else:
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raise ValueError(
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"Granularity must be year, quarter, month, week or day for value %s" % value
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)
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return datetime.combine(result, time.min) if is_datetime else result
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def end_of(value: D, granularity: Granularity) -> D:
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"""
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Get end of a time period from a date or a datetime.
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:param value: initial date or datetime.
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:param granularity: Type of period in string, can be year, quarter, month, week, day or hour.
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:return: A date/datetime object corresponding to the start of the specified period.
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"""
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is_datetime = isinstance(value, datetime)
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if granularity == "year":
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result = value.replace(month=12, day=31)
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elif granularity == "quarter":
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# Q1 = Mar 31st
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# Q2 = Jun 30th
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# Q3 = Sep 30th
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# Q4 = Dec 31st
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result = get_quarter(value)[1]
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elif granularity == "month":
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result = value + relativedelta(day=1, months=1, days=-1)
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elif granularity == 'week':
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# `calendar.weekday` uses ISO8601 for start of week reference, this means that
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# by default MONDAY is the first day of the week and SUNDAY is the last.
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result = value + relativedelta(days=6-calendar.weekday(value.year, value.month, value.day))
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elif granularity == "day":
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result = value
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elif granularity == "hour" and is_datetime:
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return datetime.combine(value, time.max).replace(hour=value.hour)
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elif is_datetime:
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raise ValueError(
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"Granularity must be year, quarter, month, week, day or hour for value %s" % value
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)
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else:
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raise ValueError(
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"Granularity must be year, quarter, month, week or day for value %s" % value
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)
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return datetime.combine(result, time.max) if is_datetime else result
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def add(value: D, *args, **kwargs) -> D:
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"""
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Return the sum of ``value`` and a :class:`relativedelta`.
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:param value: initial date or datetime.
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:param args: positional args to pass directly to :class:`relativedelta`.
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:param kwargs: keyword args to pass directly to :class:`relativedelta`.
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:return: the resulting date/datetime.
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"""
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return value + relativedelta(*args, **kwargs)
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def subtract(value: D, *args, **kwargs) -> D:
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"""
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Return the difference between ``value`` and a :class:`relativedelta`.
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:param value: initial date or datetime.
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:param args: positional args to pass directly to :class:`relativedelta`.
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:param kwargs: keyword args to pass directly to :class:`relativedelta`.
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:return: the resulting date/datetime.
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"""
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return value - relativedelta(*args, **kwargs)
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def date_range(start: D, end: D, step: relativedelta = relativedelta(months=1)) -> Iterator[datetime]:
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"""Date range generator with a step interval.
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:param start: beginning date of the range.
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:param end: ending date of the range.
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:param step: interval of the range.
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:return: a range of datetime from start to end.
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"""
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if isinstance(start, datetime) and isinstance(end, datetime):
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are_naive = start.tzinfo is None and end.tzinfo is None
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are_utc = start.tzinfo == pytz.utc and end.tzinfo == pytz.utc
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# Cases with miscellenous timezone are more complexe because of DST.
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are_others = start.tzinfo and end.tzinfo and not are_utc
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if are_others and start.tzinfo.zone != end.tzinfo.zone:
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raise ValueError("Timezones of start argument and end argument seem inconsistent")
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if not are_naive and not are_utc and not are_others:
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raise ValueError("Timezones of start argument and end argument mismatch")
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dt = start.replace(tzinfo=None)
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end_dt = end.replace(tzinfo=None)
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post_process = start.tzinfo.localize if start.tzinfo else lambda dt: dt
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elif isinstance(start, date) and isinstance(end, date):
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# FIXME: not correctly typed, and will break if the step is a fractional
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# day: `relativedelta` will return a datetime, which can't be
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# compared with a `date`
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dt, end_dt = start, end
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post_process = lambda dt: dt
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else:
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raise ValueError("start/end should be both date or both datetime type")
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if start > end:
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raise ValueError("start > end, start date must be before end")
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if start == start + step:
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raise ValueError("Looks like step is null")
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while dt <= end_dt:
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yield post_process(dt)
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dt = dt + step
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def weeknumber(locale: babel.Locale, date: date) -> Tuple[int, int]:
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"""Computes the year and weeknumber of `date`. The week number is 1-indexed
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(so the first week is week number 1).
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For ISO locales (first day of week = monday, min week days = 4) the concept
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is clear and the Python stdlib implements it directly.
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For other locales, it's basically nonsensical as there is no actual
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definition. For now we will implement non-split first-day-of-year, that is
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the first week of the year is the one which contains the first day of the
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year (taking first day of week in account), and the days of the previous
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year which are part of that week are considered to be in the next year for
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calendaring purposes.
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That is December 27, 2015 is in the first week of 2016.
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An alternative is to split the week in two, so the week from December 27,
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2015 to January 2, 2016 would be *both* W53/2015 and W01/2016.
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"""
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if locale.first_week_day == 0 and locale.min_week_days == 4:
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# woohoo nothing to do
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return date.isocalendar()[:2]
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# first find the first day of the first week of the next year, if the
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# reference date is after that then it must be in the first week of the next
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# year, remove this if we decide to implement split weeks instead
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fdny = date.replace(year=date.year + 1, month=1, day=1) \
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- relativedelta(weekday=weekdays[locale.first_week_day](-1))
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if date >= fdny:
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return date.year + 1, 1
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# otherwise get the number of periods of 7 days between the first day of the
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# first week and the reference
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fdow = date.replace(month=1, day=1) \
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- relativedelta(weekday=weekdays[locale.first_week_day](-1))
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doy = (date - fdow).days
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return date.year, (doy // 7 + 1)
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