#!/usr/bin/env python


__license__   = 'GPL v3'
__copyright__ = '2010, Kovid Goyal <kovid@kovidgoyal.net>'
__docformat__ = 'restructuredtext en'

import re
from datetime import datetime, time as dtime, timedelta, MINYEAR, MAXYEAR
from functools import partial

from calibre import strftime
from calibre.constants import iswindows, ismacos, preferred_encoding
from calibre.utils.iso8601 import utc_tz, local_tz, UNDEFINED_DATE
from calibre.utils.localization import lcdata
from polyglot.builtins import native_string_type

_utc_tz = utc_tz
_local_tz = local_tz

# When parsing ambiguous dates that could be either dd-MM Or MM-dd use the
# user's locale preferences
if iswindows:
    import ctypes
    LOCALE_SSHORTDATE, LOCALE_USER_DEFAULT = 0x1f, 0
    buf = ctypes.create_string_buffer(b'\0', 255)
    try:
        ctypes.windll.kernel32.GetLocaleInfoA(LOCALE_USER_DEFAULT, LOCALE_SSHORTDATE, buf, 255)
        parse_date_day_first = buf.value.index(b'd') < buf.value.index(b'M')
    except:
        parse_date_day_first = False
    del ctypes, LOCALE_SSHORTDATE, buf, LOCALE_USER_DEFAULT
elif ismacos:
    try:
        from calibre_extensions.usbobserver import date_format
        date_fmt = date_format()
        parse_date_day_first = date_fmt.index('d') < date_fmt.index('M')
    except:
        parse_date_day_first = False
else:
    try:
        def first_index(raw, queries):
            for q in queries:
                try:
                    return raw.index(native_string_type(q))
                except ValueError:
                    pass
            return -1

        import locale
        raw = locale.nl_langinfo(locale.D_FMT)
        parse_date_day_first = first_index(raw, ('%d', '%a', '%A')) < first_index(raw, ('%m', '%b', '%B'))
        del raw, first_index
    except:
        parse_date_day_first = False

DEFAULT_DATE = datetime(2000,1,1, tzinfo=utc_tz)
EPOCH = datetime(1970, 1, 1, tzinfo=_utc_tz)


def is_date_undefined(qt_or_dt):
    d = qt_or_dt
    if d is None:
        return True
    if hasattr(d, 'toString'):
        if hasattr(d, 'date'):
            d = d.date()
        try:
            d = datetime(d.year(), d.month(), d.day(), tzinfo=utc_tz)
        except ValueError:
            return True  # Undefined QDate
    return d.year < UNDEFINED_DATE.year or (
            d.year == UNDEFINED_DATE.year and
            d.month == UNDEFINED_DATE.month and
            d.day == UNDEFINED_DATE.day)


_iso_pat = None


def iso_pat():
    global _iso_pat
    if _iso_pat is None:
        _iso_pat = re.compile(r'\d{4}[/.-]\d{1,2}[/.-]\d{1,2}')
    return _iso_pat


def parse_date(date_string, assume_utc=False, as_utc=True, default=None):
    '''
    Parse a date/time string into a timezone aware datetime object. The timezone
    is always either UTC or the local timezone.

    :param assume_utc: If True and date_string does not specify a timezone,
    assume UTC, otherwise assume local timezone.

    :param as_utc: If True, return a UTC datetime

    :param default: Missing fields are filled in from default. If None, the
    current month and year are used.
    '''
    from dateutil.parser import parse
    if not date_string:
        return UNDEFINED_DATE
    if isinstance(date_string, bytes):
        date_string = date_string.decode(preferred_encoding, 'replace')
    if default is None:
        func = datetime.utcnow if assume_utc else datetime.now
        default = func().replace(day=15, hour=0, minute=0, second=0, microsecond=0,
                tzinfo=_utc_tz if assume_utc else _local_tz)
    if iso_pat().match(date_string) is not None:
        dt = parse(date_string, default=default)
    else:
        dt = parse(date_string, default=default, dayfirst=parse_date_day_first)
    if dt.tzinfo is None:
        dt = dt.replace(tzinfo=_utc_tz if assume_utc else _local_tz)
    return dt.astimezone(_utc_tz if as_utc else _local_tz)


def fix_only_date(val):
    n = val + timedelta(days=1)
    if n.month > val.month:
        val = val.replace(day=val.day-1)
    if val.day == 1:
        val = val.replace(day=2)
    return val


def parse_only_date(raw, assume_utc=True, as_utc=True):
    '''
    Parse a date string that contains no time information in a manner that
    guarantees that the month and year are always correct in all timezones, and
    the day is at most one day wrong.
    '''
    f = utcnow if assume_utc else now
    default = f().replace(hour=0, minute=0, second=0, microsecond=0,
            day=15)
    return fix_only_date(parse_date(raw, default=default, assume_utc=assume_utc, as_utc=as_utc))


def strptime(val, fmt, assume_utc=False, as_utc=True):
    dt = datetime.strptime(val, fmt)
    if dt.tzinfo is None:
        dt = dt.replace(tzinfo=_utc_tz if assume_utc else _local_tz)
    return dt.astimezone(_utc_tz if as_utc else _local_tz)


def dt_factory(time_t, assume_utc=False, as_utc=True):
    dt = datetime(*(time_t[0:6]))
    if dt.tzinfo is None:
        dt = dt.replace(tzinfo=_utc_tz if assume_utc else _local_tz)
    return dt.astimezone(_utc_tz if as_utc else _local_tz)


def safeyear(x):
    return min(max(x, MINYEAR), MAXYEAR)


def qt_to_dt(qdate_or_qdatetime, as_utc=True):
    o = qdate_or_qdatetime
    if o is None:
        return UNDEFINED_DATE
    if hasattr(o, 'toUTC'):
        # QDateTime
        o = o.toUTC()
        d, t = o.date(), o.time()
        try:
            ans = datetime(safeyear(d.year()), d.month(), d.day(), t.hour(), t.minute(), t.second(), t.msec()*1000, utc_tz)
        except ValueError:
            ans = datetime(safeyear(d.year()), d.month(), 1, t.hour(), t.minute(), t.second(), t.msec()*1000, utc_tz)
        if not as_utc:
            ans = ans.astimezone(local_tz)
        return ans

    try:
        dt = datetime(safeyear(o.year()), o.month(), o.day()).replace(tzinfo=_local_tz)
    except ValueError:
        dt = datetime(safeyear(o.year()), o.month(), 1).replace(tzinfo=_local_tz)
    return dt.astimezone(_utc_tz if as_utc else _local_tz)


def fromtimestamp(ctime, as_utc=True):
    dt = datetime.utcfromtimestamp(ctime).replace(tzinfo=_utc_tz)
    if not as_utc:
        dt = dt.astimezone(_local_tz)
    return dt


def fromordinal(day, as_utc=True):
    return datetime.fromordinal(day).replace(
            tzinfo=_utc_tz if as_utc else _local_tz)


def isoformat(date_time, assume_utc=False, as_utc=True, sep='T'):
    if not hasattr(date_time, 'tzinfo'):
        return str(date_time.isoformat())
    if date_time.tzinfo is None:
        date_time = date_time.replace(tzinfo=_utc_tz if assume_utc else
                _local_tz)
    date_time = date_time.astimezone(_utc_tz if as_utc else _local_tz)
    # native_string_type(sep) because isoformat barfs with unicode sep on python 2.x
    return str(date_time.isoformat(native_string_type(sep)))


def internal_iso_format_string():
    return 'yyyy-MM-ddThh:mm:ss'


def w3cdtf(date_time, assume_utc=False):
    if hasattr(date_time, 'tzinfo'):
        if date_time.tzinfo is None:
            date_time = date_time.replace(tzinfo=_utc_tz if assume_utc else
                    _local_tz)
        date_time = date_time.astimezone(_utc_tz if as_utc else _local_tz)
    return str(date_time.strftime('%Y-%m-%dT%H:%M:%SZ'))


def as_local_time(date_time, assume_utc=True):
    if not hasattr(date_time, 'tzinfo'):
        return date_time
    if date_time.tzinfo is None:
        date_time = date_time.replace(tzinfo=_utc_tz if assume_utc else
                _local_tz)
    return date_time.astimezone(_local_tz)


def dt_as_local(dt):
    if dt.tzinfo is local_tz:
        return dt
    return dt.astimezone(local_tz)


def as_utc(date_time, assume_utc=True):
    if not hasattr(date_time, 'tzinfo'):
        return date_time
    if date_time.tzinfo is None:
        date_time = date_time.replace(tzinfo=_utc_tz if assume_utc else
                _local_tz)
    return date_time.astimezone(_utc_tz)


def now():
    return datetime.now().replace(tzinfo=_local_tz)


def utcnow():
    return datetime.utcnow().replace(tzinfo=_utc_tz)


def utcfromtimestamp(stamp):
    try:
        return datetime.utcfromtimestamp(stamp).replace(tzinfo=_utc_tz)
    except Exception:
        # Raised if stamp is out of range for the platforms gmtime function
        # For example, this happens with negative values on windows
        try:
            return EPOCH + timedelta(seconds=stamp)
        except Exception:
            # datetime can only represent years between 1 and 9999
            import traceback
            traceback.print_exc()
    return utcnow()


def timestampfromdt(dt, assume_utc=True):
    return (as_utc(dt, assume_utc=assume_utc) - EPOCH).total_seconds()

# Format date functions {{{


def fd_format_hour(dt, ampm, hr):
    l = len(hr)
    h = dt.hour
    if ampm:
        h = h%12
    if l == 1:
        return '%d'%h
    return '%02d'%h


def fd_format_minute(dt, ampm, min):
    l = len(min)
    if l == 1:
        return '%d'%dt.minute
    return '%02d'%dt.minute


def fd_format_second(dt, ampm, sec):
    l = len(sec)
    if l == 1:
        return '%d'%dt.second
    return '%02d'%dt.second


def fd_format_ampm(dt, ampm, ap):
    res = strftime('%p', t=dt.timetuple())
    if ap == 'AP':
        return res
    return res.lower()


def fd_format_day(dt, ampm, dy):
    l = len(dy)
    if l == 1:
        return '%d'%dt.day
    if l == 2:
        return '%02d'%dt.day
    return lcdata['abday' if l == 3 else 'day'][(dt.weekday() + 1) % 7]


def fd_format_month(dt, ampm, mo):
    l = len(mo)
    if l == 1:
        return '%d'%dt.month
    if l == 2:
        return '%02d'%dt.month
    return lcdata['abmon' if l == 3 else 'mon'][dt.month - 1]


def fd_format_year(dt, ampm, yr):
    if len(yr) == 2:
        return '%02d'%(dt.year % 100)
    return '%04d'%dt.year


fd_function_index = {
        'd': fd_format_day,
        'M': fd_format_month,
        'y': fd_format_year,
        'h': fd_format_hour,
        'm': fd_format_minute,
        's': fd_format_second,
        'a': fd_format_ampm,
        'A': fd_format_ampm,
    }


def fd_repl_func(dt, ampm, mo):
    s = mo.group(0)
    if not s:
        return ''
    return fd_function_index[s[0]](dt, ampm, s)


def format_date(dt, format, assume_utc=False, as_utc=False):
    ''' Return a date formatted as a string using a subset of Qt's formatting codes '''
    if not format:
        format = 'dd MMM yyyy'

    if not isinstance(dt, datetime):
        dt = datetime.combine(dt, dtime())

    if hasattr(dt, 'tzinfo'):
        if dt.tzinfo is None:
            dt = dt.replace(tzinfo=_utc_tz if assume_utc else
                    _local_tz)
        dt = dt.astimezone(_utc_tz if as_utc else _local_tz)

    if format == 'iso':
        return isoformat(dt, assume_utc=assume_utc, as_utc=as_utc)

    if dt == UNDEFINED_DATE:
        return ''

    repl_func = partial(fd_repl_func, dt, 'ap' in format.lower())
    return re.sub(
        '(s{1,2})|(m{1,2})|(h{1,2})|(ap)|(AP)|(d{1,4}|M{1,4}|(?:yyyy|yy))',
        repl_func, format)

# }}}

# Clean date functions {{{


def cd_has_hour(tt, dt):
    tt['hour'] = dt.hour
    return ''


def cd_has_minute(tt, dt):
    tt['min'] = dt.minute
    return ''


def cd_has_second(tt, dt):
    tt['sec'] = dt.second
    return ''


def cd_has_day(tt, dt):
    tt['day'] = dt.day
    return ''


def cd_has_month(tt, dt):
    tt['mon'] = dt.month
    return ''


def cd_has_year(tt, dt):
    tt['year'] = dt.year
    return ''


cd_function_index = {
        'd': cd_has_day,
        'M': cd_has_month,
        'y': cd_has_year,
        'h': cd_has_hour,
        'm': cd_has_minute,
        's': cd_has_second
    }


def cd_repl_func(tt, dt, match_object):
    s = match_object.group(0)
    if not s:
        return ''
    return cd_function_index[s[0]](tt, dt)


def clean_date_for_sort(dt, fmt=None):
    ''' Return dt with fields not in shown in format set to a default '''
    if not fmt:
        fmt = 'yyMd'

    if not isinstance(dt, datetime):
        dt = datetime.combine(dt, dtime())

    if hasattr(dt, 'tzinfo'):
        if dt.tzinfo is None:
            dt = dt.replace(tzinfo=_local_tz)
        dt = as_local_time(dt)

    if fmt == 'iso':
        fmt = 'yyMdhms'

    tt = {'year':UNDEFINED_DATE.year, 'mon':UNDEFINED_DATE.month,
          'day':UNDEFINED_DATE.day, 'hour':UNDEFINED_DATE.hour,
          'min':UNDEFINED_DATE.minute, 'sec':UNDEFINED_DATE.second}

    repl_func = partial(cd_repl_func, tt, dt)
    re.sub('(s{1,2})|(m{1,2})|(h{1,2})|(d{1,4}|M{1,4}|(?:yyyy|yy))', repl_func, fmt)
    return dt.replace(year=tt['year'], month=tt['mon'], day=tt['day'], hour=tt['hour'],
                      minute=tt['min'], second=tt['sec'], microsecond=0)
# }}}


def replace_months(datestr, clang):
    # Replace months by english equivalent for parse_date
    frtoen = {
        '[jJ]anvier': 'jan',
        '[fF].vrier': 'feb',
        '[mM]ars': 'mar',
        '[aA]vril': 'apr',
        '[mM]ai': 'may',
        '[jJ]uin': 'jun',
        '[jJ]uillet': 'jul',
        '[aA]o.t': 'aug',
        '[sS]eptembre': 'sep',
        '[Oo]ctobre': 'oct',
        '[nN]ovembre': 'nov',
        '[dD].cembre': 'dec'}
    detoen = {
        '[jJ]anuar': 'jan',
        '[fF]ebruar': 'feb',
        '[mM].rz': 'mar',
        '[aA]pril': 'apr',
        '[mM]ai': 'may',
        '[jJ]uni': 'jun',
        '[jJ]uli': 'jul',
        '[aA]ugust': 'aug',
        '[sS]eptember': 'sep',
        '[Oo]ktober': 'oct',
        '[nN]ovember': 'nov',
        '[dD]ezember': 'dec'}

    if clang == 'fr':
        dictoen = frtoen
    elif clang == 'de':
        dictoen = detoen
    else:
        return datestr

    for k in dictoen:
        tmp = re.sub(k, dictoen[k], datestr)
        if tmp != datestr:
            break
    return tmp
