Matthias Bilger
b4c7d3d3a3
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68 lines
2.4 KiB
Python
68 lines
2.4 KiB
Python
import pytz
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import icalendar
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import datetime
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def generate_vtimezone(timezone, for_date=None):
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if not timezone or 'utc' in timezone.lower(): # UTC doesn't need a timezone definition
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return None
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if not for_date:
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for_date = now()
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try:
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z = pytz.timezone(timezone)
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except pytz.UnknownTimeZoneError:
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z = pytz.timezone('Europe/Berlin')
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if not hasattr(z, '_utc_transition_times'):
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return None
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transitions = zip(z._utc_transition_times, z._transition_info)
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try:
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dst1, std1, dst2, std2 = filter(lambda x: x[0].year in (for_date.year, for_date.year + 1),
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transitions)
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if dst1[1][1].seconds == 0:
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return _vtimezone_with_dst(std1, dst1, std2, dst2, timezone)
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else:
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return _vtimezone_with_dst(dst1, std1, dst2, std2, timezone)
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except:
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std = transitions[-1]
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if std[0].year > for_date.year:
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return None
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return _vtimezone_without_dst(std, timezone)
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def _vtimezone_without_dst(std, timezone):
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vtimezone = icalendar.Timezone(tzid=timezone)
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standard = icalendar.TimezoneStandard()
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utc_offset, dst_offset, tz_name = std[1]
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standard.add('dtstart', std[0])
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standard.add('tzoffsetfrom', utc_offset)
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standard.add('tzoffsetto', utc_offset)
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standard.add('tzname', tz_name)
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vtimezone.add_component(standard)
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return vtimezone
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def _vtimezone_with_dst(dst1, std1, dst2, std2, timezone):
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vtimezone = icalendar.Timezone(tzid=timezone)
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daylight = icalendar.TimezoneDaylight()
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utc_offset, dst_offset, tz_name = dst1[1]
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offsetfrom = std1[1][0]
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daylight.add('dtstart', dst1[0] + offsetfrom)
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daylight.add('rdate', dst1[0] + offsetfrom)
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daylight.add('rdate', dst2[0] + offsetfrom)
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daylight.add('tzoffsetfrom', offsetfrom)
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daylight.add('tzoffsetto', utc_offset)
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daylight.add('tzname', tz_name)
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vtimezone.add_component(daylight)
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standard = icalendar.TimezoneStandard()
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utc_offset, dst_offset, tz_name = std1[1]
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offsetfrom = dst1[1][0]
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standard.add('dtstart', std1[0] + offsetfrom)
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standard.add('rdate', std1[0] + offsetfrom)
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standard.add('rdate', std2[0] + offsetfrom)
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standard.add('tzoffsetfrom', offsetfrom)
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standard.add('tzoffsetto', utc_offset)
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standard.add('tzname', tz_name)
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vtimezone.add_component(standard)
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return vtimezone
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