# copyright 2003-2012 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
# contact http://www.logilab.fr/ -- mailto:contact@logilab.fr
#
# This file is part of logilab-common.
#
# logilab-common is free software: you can redistribute it and/or modify it under
# the terms of the GNU Lesser General Public License as published by the Free
# Software Foundation, either version 2.1 of the License, or (at your option) any
# later version.
#
# logilab-common is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
# FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more
# details.
#
# You should have received a copy of the GNU Lesser General Public License along
# with logilab-common.  If not, see <http://www.gnu.org/licenses/>.
"""Date manipulation helper functions."""

__docformat__ = "restructuredtext en"

import math
import re
import sys
from locale import getlocale, LC_TIME
from datetime import date, time, datetime, timedelta
from time import strptime as time_strptime
from calendar import monthrange, timegm
from typing import Union, List, Any, Optional, Generator

try:
    from mx.DateTime import RelativeDateTime, Date, DateTimeType
except ImportError:
    endOfMonth = None
    DateTimeType = datetime
else:
    endOfMonth = RelativeDateTime(months=1, day=-1)

# NOTE: should we implement a compatibility layer between date representations
#       as we have in lgc.db ?

FRENCH_FIXED_HOLIDAYS = {
    "jour_an": "%s-01-01",
    "fete_travail": "%s-05-01",
    "armistice1945": "%s-05-08",
    "fete_nat": "%s-07-14",
    "assomption": "%s-08-15",
    "toussaint": "%s-11-01",
    "armistice1918": "%s-11-11",
    "noel": "%s-12-25",
}

FRENCH_MOBILE_HOLIDAYS = {
    "paques2004": "2004-04-12",
    "ascension2004": "2004-05-20",
    "pentecote2004": "2004-05-31",
    "paques2005": "2005-03-28",
    "ascension2005": "2005-05-05",
    "pentecote2005": "2005-05-16",
    "paques2006": "2006-04-17",
    "ascension2006": "2006-05-25",
    "pentecote2006": "2006-06-05",
    "paques2007": "2007-04-09",
    "ascension2007": "2007-05-17",
    "pentecote2007": "2007-05-28",
    "paques2008": "2008-03-24",
    "ascension2008": "2008-05-01",
    "pentecote2008": "2008-05-12",
    "paques2009": "2009-04-13",
    "ascension2009": "2009-05-21",
    "pentecote2009": "2009-06-01",
    "paques2010": "2010-04-05",
    "ascension2010": "2010-05-13",
    "pentecote2010": "2010-05-24",
    "paques2011": "2011-04-25",
    "ascension2011": "2011-06-02",
    "pentecote2011": "2011-06-13",
    "paques2012": "2012-04-09",
    "ascension2012": "2012-05-17",
    "pentecote2012": "2012-05-28",
}

# XXX this implementation cries for multimethod dispatching


def get_step(dateobj: Union[date, datetime], nbdays: int = 1) -> timedelta:
    # assume date is either a python datetime or a mx.DateTime object
    if isinstance(dateobj, date):
        return ONEDAY * nbdays
    return nbdays  # mx.DateTime is ok with integers


def datefactory(
    year: int, month: int, day: int, sampledate: Union[date, datetime]
) -> Union[date, datetime]:
    # assume date is either a python datetime or a mx.DateTime object
    if isinstance(sampledate, datetime):
        return datetime(year, month, day)
    if isinstance(sampledate, date):
        return date(year, month, day)
    return Date(year, month, day)


def weekday(dateobj: Union[date, datetime]) -> int:
    # assume date is either a python datetime or a mx.DateTime object
    if isinstance(dateobj, date):
        return dateobj.weekday()
    return dateobj.day_of_week


def str2date(datestr: str, sampledate: Union[date, datetime]) -> Union[date, datetime]:
    # NOTE: datetime.strptime is not an option until we drop py2.4 compat
    year, month, day = [int(chunk) for chunk in datestr.split("-")]
    return datefactory(year, month, day, sampledate)


def days_between(start: Union[date, datetime], end: Union[date, datetime]) -> int:
    if isinstance(start, date):
        # mypy: No overload variant of "__sub__" of "datetime" matches argument type "date"
        # we ensure that end is a date
        assert isinstance(end, date)
        delta = end - start  # type: ignore
        # datetime.timedelta.days is always an integer (floored)
        if delta.seconds:
            return delta.days + 1
        return delta.days
    else:
        return int(math.ceil((end - start).days))


def get_national_holidays(
    begin: Union[date, datetime], end: Union[date, datetime]
) -> Union[List[date], List[datetime]]:
    """return french national days off between begin and end"""
    begin = datefactory(begin.year, begin.month, begin.day, begin)
    end = datefactory(end.year, end.month, end.day, end)
    holidays = [str2date(datestr, begin) for datestr in FRENCH_MOBILE_HOLIDAYS.values()]
    for year in range(begin.year, end.year + 1):
        for datestr in FRENCH_FIXED_HOLIDAYS.values():
            date = str2date(datestr % year, begin)
            if date not in holidays:
                holidays.append(date)
    return [day for day in holidays if begin <= day < end]


def add_days_worked(start: date, days: int) -> date:
    """adds date but try to only take days worked into account"""
    step = get_step(start)
    weeks, plus = divmod(days, 5)
    end = start + ((weeks * 7) + plus) * step
    if weekday(end) >= 5:  # saturday or sunday
        end += 2 * step
    end += len([x for x in get_national_holidays(start, end + step) if weekday(x) < 5]) * step
    if weekday(end) >= 5:  # saturday or sunday
        end += 2 * step
    return end


def nb_open_days(start: Union[date, datetime], end: Union[date, datetime]) -> int:
    assert start <= end
    step = get_step(start)
    days = days_between(start, end)
    weeks, plus = divmod(days, 7)
    if weekday(start) > weekday(end):
        plus -= 2
    elif weekday(end) == 6:
        plus -= 1
    open_days = weeks * 5 + plus
    nb_week_holidays = len(
        [x for x in get_national_holidays(start, end + step) if weekday(x) < 5 and x < end]
    )
    open_days -= nb_week_holidays
    if open_days < 0:
        return 0
    return open_days


def date_range(
    begin: date, end: date, incday: Optional[Any] = None, incmonth: Optional[bool] = None
) -> Generator[date, Any, None]:
    """yields each date between begin and end

    :param begin: the start date
    :param end: the end date
    :param incr: the step to use to iterate over dates. Default is
                 one day.
    :param include: None (means no exclusion) or a function taking a
                    date as parameter, and returning True if the date
                    should be included.

    When using mx datetime, you should *NOT* use incmonth argument, use instead
    oneDay, oneHour, oneMinute, oneSecond, oneWeek or endOfMonth (to enumerate
    months) as `incday` argument
    """
    assert not (incday and incmonth)
    begin = todate(begin)
    end = todate(end)
    if incmonth:
        while begin < end:
            yield begin
            begin = next_month(begin, incmonth)
    else:
        incr = get_step(begin, incday or 1)
        while begin < end:
            yield begin
            begin += incr


# makes py datetime usable #####################################################

ONEDAY: timedelta = timedelta(days=1)
ONEWEEK: timedelta = timedelta(days=7)


def strptime_time(value, format="%H:%M"):
    return time(*time_strptime(value, format)[3:6])


def todate(somedate: date) -> date:
    """return a date from a date (leaving unchanged) or a datetime"""
    if isinstance(somedate, datetime):
        return date(somedate.year, somedate.month, somedate.day)
    assert isinstance(somedate, (date, DateTimeType)), repr(somedate)
    return somedate


def totime(somedate):
    """return a time from a time (leaving unchanged), date or datetime"""
    # XXX mx compat
    if not isinstance(somedate, time):
        return time(somedate.hour, somedate.minute, somedate.second)
    assert isinstance(somedate, (time)), repr(somedate)
    return somedate


def todatetime(somedate):
    """return a date from a date (leaving unchanged) or a datetime"""
    # take care, datetime is a subclass of date
    if isinstance(somedate, datetime):
        return somedate
    assert isinstance(somedate, (date, DateTimeType)), repr(somedate)
    return datetime(somedate.year, somedate.month, somedate.day)


def datetime2ticks(somedate: Union[date, datetime]) -> int:
    return timegm(somedate.timetuple()) * 1000 + int(getattr(somedate, "microsecond", 0) / 1000)


def ticks2datetime(ticks: int) -> datetime:
    miliseconds, microseconds = divmod(ticks, 1000)
    try:
        return datetime.fromtimestamp(miliseconds)
    except (ValueError, OverflowError):
        epoch = datetime.fromtimestamp(0)
        nb_days, seconds = divmod(int(miliseconds), 86400)
        delta = timedelta(nb_days, seconds=seconds, microseconds=microseconds)
        try:
            return epoch + delta
        except (ValueError, OverflowError):
            raise


def days_in_month(somedate: date) -> int:
    return monthrange(somedate.year, somedate.month)[1]


def days_in_year(somedate):
    feb = date(somedate.year, 2, 1)
    if days_in_month(feb) == 29:
        return 366
    else:
        return 365


def previous_month(somedate, nbmonth=1):
    while nbmonth:
        somedate = first_day(somedate) - ONEDAY
        nbmonth -= 1
    return somedate


def next_month(somedate: date, nbmonth: int = 1) -> date:
    while nbmonth:
        somedate = last_day(somedate) + ONEDAY
        nbmonth -= 1
    return somedate


def first_day(somedate):
    return date(somedate.year, somedate.month, 1)


def last_day(somedate: date) -> date:
    return date(somedate.year, somedate.month, days_in_month(somedate))


def ustrftime(somedate: datetime, fmt: str = "%Y-%m-%d") -> str:
    """like strftime, but returns a unicode string instead of an encoded
    string which may be problematic with localized date.
    """
    if sys.version_info >= (3, 3):
        # datetime.date.strftime() supports dates since year 1 in Python >=3.3.
        return somedate.strftime(fmt)
    else:
        try:
            if sys.version_info < (3, 0):
                encoding = getlocale(LC_TIME)[1] or "ascii"
                return str(somedate.strftime(str(fmt)), encoding)
            else:
                return somedate.strftime(fmt)
        except ValueError:
            if somedate.year >= 1900:
                raise
            # datetime is not happy with dates before 1900
            # we try to work around this, assuming a simple
            # format string
            fields = {
                "Y": somedate.year,
                "m": somedate.month,
                "d": somedate.day,
            }
            if isinstance(somedate, datetime):
                fields.update({"H": somedate.hour, "M": somedate.minute, "S": somedate.second})
            fmt = re.sub("%([YmdHMS])", r"%(\1)02d", fmt)
            return str(fmt) % fields


def utcdatetime(dt: datetime) -> datetime:
    if dt.tzinfo is None:
        return dt
    # mypy: No overload variant of "__sub__" of "datetime" matches argument type "None"
    return dt.replace(tzinfo=None) - dt.utcoffset()  # type: ignore


def utctime(dt):
    if dt.tzinfo is None:
        return dt
    return (dt + dt.utcoffset() + dt.dst()).replace(tzinfo=None)


def datetime_to_seconds(date):
    """return the number of seconds since the begining of the day for that date"""
    return date.second + 60 * date.minute + 3600 * date.hour


def timedelta_to_days(delta):
    """return the time delta as a number of seconds"""
    return delta.days + delta.seconds / (3600 * 24)


def timedelta_to_seconds(delta):
    """return the time delta as a fraction of days"""
    return delta.days * (3600 * 24) + delta.seconds
